Abstract: During recent years different approaches have been explored to raise effective antitumor responses against brain tumors and particularly glioblastomas (GBMs). In most cases, cancer vaccines were based on autologous dendritic cells loaded with GBM peptides or whole tumor lysates. Many phase I-II studies showed that such strategy is feasible and nontoxic but failed to provide convincing evidence of its efficacy. This was due to study design and other biological issues: local immune suppression and insufficient characterization of appropriate epitopes appear as particularly relevant.
Abstract: IL-17A, produced by Th17 cells, may play a dual role in antitumor immunity. Using the GL261-glioma model, we investigated the effects of Th17 cells on tumor growth and microenvironment. Th17 cells infiltrate mouse gliomas, increase significantly in a time-dependent manner similarly to Treg and do not express Foxp3. To characterize the direct effects of Th17 cells on GL261 murine gliomas and on tumor microenvironment, we isolated IL-17-producing cells enriched from splenocytes derived from naïve (nTh17) or glioma-bearing mice (gTh17) and pre-stimulated in vitro with or without TGF-β. Spleen-derived Th17 cells co-expressing IL-17, IFN-γ and IL-10, but not Treg marker Foxp3, were co-injected intracranially with GL261 in immune-competent mice. Mice co-injected with GL261 and nTh17 survived significantly longer than gTh17 (P < 0.006) and gliomas expressed high level of IFN-γ and TNF-α, low levels of IL-10 and TGF-β. In vitro IL-17 per se did not exert effects on GL261 proliferation; in vivo gliomas grew equally well intracranially in IL-17 deficient and wild-type mice. We further analyzed relationship between Th17 cells and Treg. Treg were significantly higher in splenocytes from glioma-bearing than naïve mice (P = 0.01) and gTh17 produced more IL-10 than IFN-γ (P = 0.002). In vitro depletion of Treg using PC61 in splenocytes from glioma-bearing mice causes increased IL-17/IFN-γ cells (P = 0.007) and decreased IL-17/IL-10 cells (P = 0.03). These results suggest that Th17 polarization may be induced by Treg and that Th17 cells in gliomas modulate tumor growth depending on locally produced cytokines.
Abstract: Secreted WNT proteins signal through ten receptors of the frizzled (FZD) family. Because of the relevance of the WNT/β-catenin (CTNNB1) signaling pathway in medulloblastomas (MBs), we investigated the expression of all ten members of the FZD gene family (FZD1-10) in 17 human MBs, four MB cell lines and in normal human cerebellum, using real-time PCR. We found that FZD2 transcript was over-expressed in all MBs and MB cell lines. Western blot analysis confirmed the expression of FZD2 at the protein level. Moreover, the levels of FZD2 transcript were found to correlate with those of ASPM transcript, a marker of mitosis essential for mitotic spindle function. Accordingly, ASPM mRNA was expressed at a very low level in the adult, post-mitotic, human cerebellum, at higher levels in fetal cerebellum and at highest levels in MB tissues and cell lines. Unlike FZD2, the other FZDs were overexpressed (e.g., FZD1, FZD3 and FZD8) or underexpressed (e.g., FZD7, FZD9 and FZD10) in a case-restricted manner. Interestingly, we did not find any nuclear immuno-reactivity to CTNNB1 in four MBs over-expressing both FZD2 and other FZD receptors, confirming the lack of nuclear CTNNB1 staining in the presence of increased FZD expression, as in other tumor types. Overall, our results indicate that altered expression of FZD2 might be associated with a proliferative status, thus playing a role in the biology of human MBs, and possibly of cerebellar progenitors from which these malignancies arise.
Abstract: A number of studies in murine models have suggested that the immune system may edit different tumors by forcing their expression profiles so that they escape immune reactions and proliferate. Glioblastoma (GB), the most frequent and aggressive primary brain tumor, provides a good example of this, thanks to the production of numerous immunosuppressive molecules (with TGF-β being of paramount importance), downregulation of the MHC complex and deregulation of the potential for antigen presentation by the surrounding microglia. Given that surgery, radiotherapy and chemotherapy with available protocols have limited effects on the survival of GB patients, different immunotherapy strategies have been developed, based on the use of dendritic cells, antibodies and peptide vaccination. Presently, bevacizumab, a humanized anti-VEGF antibody, provides the most successful example for immune-based treatment of GB, however, its action is limited in time, as the often tumor relapses due to still undefined immunoediting mechanisms. Altered function of EGF receptor-driven pathways is common in GB and is most frequently due to the presence of a deleted form named EGFRvIII, providing a unique cancer epitope that has been targeted by immunotherapy. A recent trial of GB immunotherapy based on vaccination with the EGFRvIII peptide has shown clinical benefit: interestingly most GBs at relapse were negative for EGFRvIII expression, a relevant, direct example of cancer immunoediting. Investigations on the mechanisms of GB immunoediting will lead to an increased understanding of the biology of this malignancy and hopefully provide novel therapeutic targets.
Abstract: Meningiomas are the most frequent intracranial tumors. Surgery can be curative, but recurrences are possible. We performed gene expression analyses and loss of heterozygosity (LOH) studies looking for new markers predicting the recurrence risk. We analyzed expression profiles of 23 meningiomas (10 grade I, 10 grade II, and 3 grade III) and validated the data using quantitative polymerase chain reaction (qPCR). We performed LOH analysis on 40 meningiomas, investigating chromosomal regions on 1p, 9p, 10q, 14q, and 22q. We found 233 and 268 probe sets to be significantly down- and upregulated, respectively, in grade II or III meningiomas. Genes downregulated in high-grade meningiomas were overrepresented on chromosomes 1, 6, 9, 10, and 14. Based on functional enrichment analysis, we selected LIM domain and actin binding 1 (LIMA1), tissue inhibitor of metalloproteinases 3 (TIMP3), cyclin-dependent kinases regulatory subunit 2 (CKS2), leptin receptor (LEPR), and baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) for validation using qPCR and confirmed their differential expression in the two groups of tumors. We calculated ΔCt values of CKS2 and LEPR and found that their differential expression (C-L index) was significantly higher in grade I than in grade II or III meningiomas (p < .0001). Interestingly, the C-L index of nine grade I meningiomas from patients who relapsed in <5 years was significantly lower than in grade I meningiomas from patients who did not relapse. These findings indicate that the C-L index may be relevant to define the progression risk in meningioma patients, helping guide their clinical management. A prospective analysis on a larger number of cases is warranted.
Abstract: Proteins of the Polycomb repressive complex 2 (PRC2) are epigenetic gene silencers and are involved in tumour development. Their oncogenic function might be associated with their role in stem cell maintenance. The histone methyltransferase Enhancer of Zeste 2 (EZH2) is a key member of PRC2 function: we have investigated its expression and function in gliomas.
Abstract: Pilot data showed that adding intratumoral (IT) injection of dendritic cells (DCs) prolongs survival of patients affected by glioblastoma multiforme (GBM) treated by subcutaneous (SC) delivery of DCs. Using a murine model resembling GBM, we investigated the immunological mechanisms underlying this effect. C57BL6/N mice received brain injections of GL261 glioma cells. Seven days later, mice were treated by 3 SC injections of DCs with or without 1 IT injection of DCs. DC maturation, induced by pulsing with GL261 lysates, was necessary to develop effective immune responses. IT injection of pulsed (pDC), but not unpulsed DCs (uDC), increased significantly the survival, either per se or in combination with SC-pDC (P < .001 vs controls). Mice treated by IT-pDC plus SC-pDC survived longer than mice treated by SC-pDC only (P = .03). Injected pDC were detectable in tumor parenchyma, but not in cervical lymph nodes. In gliomas injected with IT-pDC, CD8+ cells were significantly more abundant and Foxp3+ cells were significantly less abundant than in other groups. Using real-time polymerase chain reaction, we also found enhanced expression of IFN-gamma and TNF-alpha and decreased expression of transforming growth factor-beta (TGF-beta) and Foxp3 in mice treated with SC-pDC and IT-pDC. In vitro, pDC produced more TNF-alpha than uDC: addition of TNF-alpha to the medium decreased the proliferation of glioma cells. Overall, the results suggest that IT-pDC potentiates the anti-tumor immune response elicited by SC-pDC by pro-immune modulation of cytokines in the tumor microenvironment, decrease of Treg cells, and direct inhibition of tumor proliferation by TNF-alpha.
Abstract: Aim: To evaluate MGMT promoter hypermethylation as prognostic factor in a retrospective study of 104 cases of glioblastoma multiforme (GBM). MATERIALS AND METHODS: The O(6)-methylguanine-DNA methyltransferase (MGMT) status was evaluated by methylation-specific PCR (MSP), immunohistochemistry and Western blotting analysis in formalin-fixed paraffin-embedded surgical samples. RESULTS: The MGMT gene was found to be methylated in 29 of 101 tumors (28.7%) by MSP, according to the evaluation methods employed. By immunohistochemistry, different categories were identified on the basis of reaction intensity, percentage of positive cells and homogeneous or heterogeneous distribution. MSP did not correlate with immunohistochemistry, with the exception of the category with the highest percentage of positive cells and homogeneity of immunostaining. Western blotting analysis correlated with immunohistochemical findings (Pearson's correlation coefficient r=0.268, p=0.0211), but not with MSP. By Kaplan-Meier survival analysis, radiotherapy was a significant prognostic factor (p=0.0001). When uncensored patients alone were considered, MGMT methylation status showed a significant correlation with survival (p=0.026). Temozolomide therapy correlated with survival (p=0.022), but not with MGMT methylation. After multivariate Cox regression analysis, only radiotherapy remained as an independent prognostic factor (p=0.0001). CONCLUSION: Correlation was inconclusive among MSP, immunohistochemistry and Western blotting analysis, despite the sophisticated score system for the immunohistochemical quantitative evaluation. MGMT expression is a complex event in which many factors beside epigenetic silencing are implicated.
Abstract: Abstract Glioblastoma multiforme (GBM), the highest-grade glioma, is the most frequent tumour of the brain with a very poor prognosis and limited therapeutic options. Although little is known about the molecular mechanisms that underlie glioblastoma formation, a number of signal transduction routes, such as the Notch and Ras signalling pathways, seem to play an important role in the formation of GBM. In the present study, we show by in situ hybridization on primary tumour material that the transcription factor HEY1, a target of the Notch signalling pathway, is specifically up-regulated in glioma and that expression of HEY1 in GBM correlates with tumour-grade and survival. In addition, we show by chromatin immunoprecipitations, luciferase assays and Northern blot experiments that HEY1 is a bona fide target of the E2F family of transcription factors, connecting the Ras and Notch signalling pathways. Finally, we show that ectopic expression of HEY1 induces cell proliferation in neural stem cells, while depletion of HEY1 by RNA interference reduces proliferation of glioblastoma cells in tissue culture. Together, these data imply a role for HEY1 in the progression of GBM, and therefore we propose that HEY1 may be a therapeutic target for glioblastoma patients. Moreover, HEY1 may represent a molecular marker to distinguish GBM patients with a longer survival prognosis from those at high risk.
Abstract: In recent years the amount of information concerning the genetics and the biology of gliomas, and particularly of glioblastoma multiforme, increased steadily. Such an increase has been paralleled by the technological progress of MRI. The merging of these scientific areas, as summarized in this review, is helping the stratification of glioma patients for clinical trials and their clinical follow-up. Although available therapeutic options appear limited in number, it is likely that in the next 5 years, both as a consequence of the increased knowledge due to genomic sequencing of hundreds of glioblastoma specimens and to continuous improvements of MRI, new perspectives will be available for these patients, with a sizable impact on their prognosis.
Abstract: Accumulating evidence suggests that only a fraction of neoplastic cells, defined as cancer stem cells (CSC), are responsible for tumor perpetuation. Recent data suggest that neurospheres (NS) from glioblastoma multiforme (GBM) are enriched in CSC. The characterization of this subpopulation of brain tumor cells with a potent tumorigenic activity supports the cancer stem cell hypothesis in solid tumors and may imply that cancer cells are differentially targeted by treatments, including dendritic cell (DC) immunotherapy. To test therapeutic strategies, a good model mimicking the characteristics of GBM-NS and GBM-AC (Adherent Cells) was necessary. One of the most frequently used murine brain tumor models is the GL261 glioma cell line. To see whether GL261 cells could mimic the growth of human GBM-CSC we let them grow in EGF/bFGF without serum. After 5 days neurospheres were visible in the culture medium and were proliferating continuously. The characterization in vivo and in vitro demonstrates that GL261-NS satisfy criteria used to identify CSC and are more immunogenic than AC. DC loaded with GL261-NS lysates protect mice against tumors from both GL261-NS and GL261-AC. Our results suggest that only DC vaccination against neurospheres can restrain the growth of a highly infiltrating and aggressive model of glioma and may have implications for the design of novel, more effective immunotherapy trials for malignant glioma and possibly other malignancies.
Abstract: In 2007, an Italian cancer research group proposed a specific concerted action aimed at the "analytical and clinica validation of new biomarkers for early diagnosis: Network, resources, methodology, quality control, and data analysis." The proposal united 37 national operative units involved in different biomarker studies and it created a strong coordinative body with the necessary expertise in methodologies, statistical analysis, quality control, and biological resources to perform ad hoc validation studies for new biomarkers of early cancer diagnosis. The action, financed by the Italian Ministry of Health within the Integrated Oncology Program (PIO) coordinated by NCI-Istituto Tumori Bari, started in 2007 and activated 7 projects, each of which focused on disease-specific biomarker studies. Overall, the 37 participating units proposed studies on 50 biomarkers, including analytical and clinical validation procedures. Clusters of units were specifically involved in research of early-detection biomarkers for cancers of the lung, digestive tract, prostate/bladder, and nervous system, as well as female cancers. Furthermore, a cluster involved in biomarkers for bioimaging and infection-related cancers was created. The first investigators' meeting, "Analytical and clinical validation of new biomarkers for early diagnosis," was held on 9 September 2008 in Bari. During this meeting, methodological aspects, scientific programs and preliminary results were presented and discussed.
Abstract: Glioblastoma multiforme (GBM) is an extremely malignant brain tumor. To identify new genomic alterations in GBM, genomic DNA of tumor tissue/explants from 55 individuals and 6 GBM cell lines were examined using single nucleotide polymorphism DNA microarray (SNP-Chip). Further gene expression analysis relied on an additional 56 GBM samples. SNP-Chip results were validated using several techniques, including quantitative PCR (Q-PCR), nucleotide sequencing, and a combination of Q-PCR and detection of microsatellite markers for loss of heterozygosity with normal copy number [acquired uniparental disomy (AUPD)]. Whole genomic DNA copy number in each GBM sample was profiled by SNP-Chip. Several signaling pathways were frequently abnormal. Either the p16(INK4A)/p15(INK4B)-CDK4/6-pRb or p14(ARF)-MDM2/4-p53 pathways were abnormal in 89% (49 of 55) of cases. Simultaneous abnormalities of both pathways occurred in 84% (46 of 55) samples. The phosphoinositide 3-kinase pathway was altered in 71% (39 of 55) GBMs either by deletion of PTEN or amplification of epidermal growth factor receptor and/or vascular endothelial growth factor receptor/platelet-derived growth factor receptor alpha. Deletion of chromosome 6q26-27 often occurred (16 of 55 samples). The minimum common deleted region included PARK2, PACRG, QKI, and PDE10A genes. Further reverse transcription Q-PCR studies showed that PARK2 expression was decreased in another collection of GBMs at a frequency of 61% (34 of 56) of samples. The 1p36.23 region was deleted in 35% (19 of 55) of samples. Notably, three samples had homozygous deletion encompassing this site. Also, a novel internal deletion of a putative tumor suppressor gene, LRP1B, was discovered causing an aberrant protein. AUPDs occurred in 58% (32 of 55) of the GBM samples and five of six GBM cell lines. A common AUPD was found at chromosome 17p13.3-12 (included p53 gene) in 13 of 61 samples and cell lines. Single-strand conformational polymorphism and nucleotide sequencing showed that 9 of 13 of these samples had homozygous p53 mutations, suggesting that mitotic recombination duplicated the abnormal p53 gene, probably providing a growth advantage to these cells. A significantly shortened survival time was found in patients with 13q14 (RB) deletion or 17p13.1 (p53) deletion/AUPD. Taken together, these results suggest that this technique is a rapid, robust, and inexpensive method to profile genome-wide abnormalities in GBM.
Abstract: In the adult mammalian brain, multipotential neural stem cells (NSC) persist throughout life in areas where neurogenesis is maintained. A distinctive trait of NSCs growing in vitro as neurospheres (NS), is their ability to self-renew, differentiate and migrate to sites of injury, such as gliomas. We have studied the role of Reelin, an extracellular matrix protein involved in brain development, in NSCs derived from normal newborn mice or from reeler, a natural mutant in which Reelin is not expressed. We show that the absence of Reelin negatively affects proliferation, NS-forming ability, and neuronal differentiation. Reeler NSCs are unable to migrate in chains, a migration mode typical of neural precursors homing to injury sites in adult CNS. All these effects are partially rescued by ectopic Reelin supplementation. Finally, we show that reeler NSCs fail to migrate in vivo towards gliomas. Overall, our results indicate that Reelin affects all major features of postnatal NSCs, and that it is required for the proper homing of NSCs to tumor sites in adult brain.
Abstract: A 60-year-old man with progressive gait ataxia and mild pyramidal signs showed at MRI a pontine lesion with post-contrast enhancement in the left middle cerebellar peduncle. Diagnosis of Erdheim-Chester disease (ECD), a rare non-Langerhans cell histiocytosis, was suggested, further supported by a previously diagnosed retroperitoneal fibrosis. X-ray films demonstrated characteristic bilateral and symmetric osteosclerosis of the long bones of the lower limbs, which at radionuclide studies exhibited a marked increase in technetium-99 uptake. A cerebral 18FDG-PET showed a relevant pontine uptake of the tracer. Re-evaluation of a past retroperitoneal biopsy showed an intense CD68+, CD1a-, and S100- infiltrate of histiocytes with foamy cytoplasm, thus confirming the diagnosis. ECD should be regarded as a rare cause of adult-onset sporadic ataxia, especially when pontine lesions and extraneurological manifestations are present.
Abstract: Reliable data on large cohorts of patients with glioblastoma are needed because such studies differ importantly from trials that have a strong bias toward the recruitment of younger patients with a higher performance status. We analyzed the outcome of 676 patients with histologically confirmed newly diagnosed glioblastoma who were treated consecutively at a single institution over a 7-year period (1997-2003) with follow-up to April 30, 2006. Survival probabilities were 57% at 1 year, 16% at 2 years, and 7% at 3 years. Progression-free survival was 15% at 1 year. Prolongation of survival was significantly associated with surgery in patients with a good performance status, whatever the patient's age, with an adjusted hazard ratio of 0.55 (p < 0.001) or a 45% relative decrease in the risk of death. Radiotherapy and chemotherapy improved survival, with adjusted hazard ratios of 0.61 (p = 0.001) and 0.89 (p = 0.04), respectively, regardless of age, performance status, or residual tumor volume. Recurrence occurred in 99% of patients throughout the follow-up. Reoperation was performed in one-fourth of these patients but was not effective, whether performed within 9 months (hazard ratio, 0.86; p = 0.256) or after 9 months (hazard ratio, 0.98; p = 0.860) of initial surgery, whereas second-line chemotherapy with procarbazine, lomustine, and vincristine (PCV) or with temozolomide improved survival (hazard ratio, 0.77; p = 0.008). Surgery followed by radiotherapy and chemotherapy should be considered in all patients with glioblastoma, and these treatments should not be withheld because of increasing age alone. The benefit of second surgery at recurrence is uncertain, and new trials are needed to assess its effectiveness. Chemotherapy with PCV or temozolomide seems to be a reasonable option at tumor recurrence.
Abstract: We report a case of glioblastoma (GBM) occurring 8 years after radiation therapy for a medulloblastoma. A 15-year-old boy underwent surgery and radiotherapy for a medulloblastoma and 8 years later he developed a second tumor at the same site. The second lesion showed different histological and molecular features, was diagnosed as a glioblastoma and fulfilled the criteria of radiation-induced neoplasm. Mutational analysis of the p53 gene showed a C to G transition at codon 176 in tumor DNA. LOH was detected at 17p and 19q. The tumor also showed O6-methylguanine-DNA methyl-transferase (MGMT) promoter methylation and no amplification of EGF receptor. In conclusion, the radiation-induced MGMT hyper-methylation and p53 mutations may have a role in the development of a subgroup of radio-induced glioma (RIG), suggesting that these molecular alterations directly cooperate in the genesis of the post-irradiation GBM. Moreover RIGs seem to be a heterogeneous group of tumors that may resemble either primary or secondary GBM.
Abstract: To gain insight into the lineage of origin of medulloblastomas, the mRNA expression of NEUROG1, a gene encoding a proneural transcription factor transiently detected during nervous system development, was investigated in 27 human medulloblastomas characterized for mRNA expression of ATOH1, a marker of cerebellar granule precursors and corresponding medulloblastomas. Expression of Ngn1, the mouse homolog of NEUROG1, was also analyzed in the mouse cerebellar primordium. In addition, we studied mRNA expression of GLI1 as a marker of the SHH pathway activation, and nuclear beta-catenin staining, beta-catenin mutations, and mRNA expression of MYC as indicators of the WNT pathway status. In 15 cases, we also examined expression of OTX2, a transcription factor recently indicated as a positive marker of medulloblastomas originating from cerebellar granule precursors. The mRNA expression of NEUROG1 and Ngn1 was selectively found in medulloblastomas not expressing ATOH1 and in progenitors of the cerebellar ventricular zone, respectively. GLI1 transcript was expressed in medulloblastomas with ATOH1 transcript, whereas high levels of MYC transcript were unrelated to NEUROG1 or ATOH1 expression. No clear association between MYC overexpression and nuclear beta-catenin staining was found. Finally, OTX2 mRNA was expressed in all medulloblastomas with NEUROG1 transcript, but also in a subset of these malignancies with ATOH1 transcript. These observations may help to define the lineage of origin of medulloblastomas, and support a role for ATOH1 and NEUROG1 in the classification of these malignancies.
Abstract: PURPOSE: Recent data suggest that methylation of the DNA repair gene O(6)-methylguanine DNA methyltransferase (MGMT), by increasing the chemosensitivity of glioblastoma multiforme, is significantly associated with improved prognosis. Results in contradiction with these findings, however, are present in the literature and the clinical and genetic context framing MGMT methylation is poorly characterized. EXPERIMENTAL DESIGN: To address these issues, we have investigated the MGMT methylation status, clinical and magnetic resonance imaging characteristics, and relevant genetic features (loss of heterozygosity on 17p and 19q, EGFR amplification, and p53 mutations) in a retrospective study on 86 patients affected by glioblastoma multiforme: 72 patients had a clinical history indicating de novo insurgence of the tumor and the remaining 14 were secondary glioblastoma multiforme. RESULTS: MGMT methylation was detected by methylation-specific PCR in 41 of 86 cases (47.7%; Meth+). Progression-free survival and overall survival were significantly longer in Meth+ than in Meth- patients [10 versus 7 months (P=0.003, log-rank test) and 18 versus 14 months (P=0.0003, log-rank test), respectively]. Mixed-nodular enhancement at magnetic resonance imaging was significantly more frequent in Meth+ and secondary glioblastoma multiforme and ring enhancement in Meth- and primary glioblastoma multiforme (P<0.005). MGMT methylation was more present in secondary glioblastoma multiforme (P=0.006) and associated with loss of heterozygosity on 17p and/or 19q (P=0.005). CONCLUSIONS: These observations suggest that MGMT methylation is part of a genetic signature of glioblastomas that developed from lower-grade gliomas.
Abstract: Although most meningiomas are slow-growing tumours associated with favourable prognosis, they often present local recurrence after surgical treatment; by contrast, extracranial metastatic meningiomas are rare, occurring in less than 1% of the cases. Risk factors for distal spread remain largely unknown. We report three cases with lung or bone metastases from intracranial recurrent meningiomas. Loss of heterozygosity (LOH) analysis on 1p, 9p, 10q, 14q, and 22q was conducted in available primary, recurrent and metastatic lesions, showing the same LOH pattern in the distal metastases and in the intracranial meningioma. LOH at 1p, 14q and 9p, known to be associated with increased aggressiveness, were found. The results highlight the potential clinical relevance of integrating histopathological studies with molecular genetic analysis in the follow-up of patients with different types of meningiomas.
Abstract: Skin stem/progenitor cells (SKPs) derive from the dermis and in culture can generate mesodermal and neural progenies. To investigate their potential for the treatment of brain diseases, we first injected SKPs into the brain of syngeneic mice. Brain histology indicated that most SKPs remained undifferentiated and clustered at the injection site, while, in vitro, 17% of SKPs expressed neural markers, as assessed by flow cytometry. After labeling with magnetodendrimers, murine and human SKPs were detected by magnetic resonance imaging even 5 months after brain injection. To evaluate their therapeutic potential on malignant gliomas, IL-4 SKPs (i.e. SKPs transduced by a lentiviral vector carrying the cDNA of the anti-glioma cytokine interleukin-4) were injected into GL261 experimental gliomas. IL-4-SKPs prolonged significantly the survival of tumor-bearing mice: furthermore, GL261 gliomas attracted SKPs originally injected into the contralateral hemisphere. Thus, prolonged survival, capacity for transgene expression, and lack of uncontrolled proliferation suggest that SKPs warrant further consideration as therapeutic tools for brain tumors and, possibly, other neurological disorders.
Abstract: Oligoastrocytomas (OAs) are WHO grade II or III tumors composed of a mixture of 2 neoplastic cell types morphologically resembling the cells in oligodendrogliomas and diffuse astrocytomas. Investigations on the genetic profile of OAs may yield important information for their classification and help for their clinical management. We have studied, in 94 OAs (46 WHO grade II and 48 WHO grade III), the patterns of loss of heterozygosity (LOH) of 4 genomic regions: 1p, 19q, 17p and 10q. Results were as follows: LOH 1p was present in 46% of the tumors; LOH 19q in 45%; LOH 17p in 22%; LOH 10q in 16%. LOH 1p and 19q were associated in 32%, other LOH associations were rare (<3%). Patients had a median follow-up of 30 months. Patients without LOH on 1p had shorter progression free survival than patients with LOH on 1p: 30 vs. 132 months, p < 0.0001. MRI indicated that tumors without LOH on 1p were often temporal (p < 0.02), and showed signal inhomogeneity on T1 and T2 images (p < 0.02) and contrast enhancement (p < 0.04). Thus, LOH on 1p identifies two subgroups of OAs. OAs without LOH on 1p behave like WHO grade II or III diffuse astrocytomas: they have shorter survival, MRI characteristics implying malignancy and genetic alterations associated with tumor progression. OAs with LOH on 1p, on the other hand, behave like WHO grade II or III oligodendrogliomas with 1p loss: they are associated with longer survival and do not have MRI or genetic alterations associated with malignancy. These findings suggest that the definition of OAs or mixed gliomas could be reshaped in agreement with the genetic information.
Abstract: Twitcher (GALC(twi/twi)) is the murine model of globoid cell leukodystrophy (GLD or Krabbe disease), a disease caused by mutations of the lysosomal enzyme galactocerebrosidase (GALC). To verify the therapeutic potential on twitcher of neural stem/progenitor cells (NSPC), we transduced them with a GALC lentiviral vector. Brain injection of NSPC-GALC increased survival of GALC(twi/twi) from 36.1 +/- 4.1 to 52.2 +/- 5.6 days (P < 0.0001). Detection of GALC activity and flow cytometry showed that NSPC-GALC and NSPC expressing the green fluorescent protein were attracted to the posterior area of twitcher brain, where demyelination occurs first. GALC(twi/twi) microglia, also more abundant in posterior regions of the brain, released significant amounts of the cytotoxic cytokine TNF-alpha when matched with NSPC-GALC. Thus, in murine GLD, and possibly in other demyelinating diseases, NSPC are attracted to regions of active demyelination but have limited survival and therapeutic potential if attacked by activated macrophages/microglia.
Abstract: Disruptions of LGI1 in glioblastoma (GBM) cell lines and LGI1 mutations in families with autosomal dominant epilepsy imply a role for LGI1 in glial cells as well as in neurons. Although we and others could not find LGI1 mutations in malignant gliomas, our initial studies appeared to support the idea that LGI1 is poorly expressed or absent in these tumors. Microarray data suggested that LGI1 could be involved in the control of matrix metalloproteinases, and we found that tumors derived from U87 glioblastoma cells overexpressing LGI1 were less aggressive than U87 control tumors. To our surprise, we observed that LGI1 expression after differentiation of murine neural stem cells was robust in neurons but negligible in glial cells, in agreement with immunohistochemistry studies on rodent brain. This observation could suggest that the variable levels of LGI1 expression in gliomas reflect the presence of neurons entrapped within the tumor. To test this hypothesis, we investigated LGI1 expression in parallel with expression of the neuronal marker NEF3 by real-time PCR on 30 malignant gliomas. Results showed a strong, positive correlation between the expression levels of these two genes (P < 0.0001). Thus, our data confirm that LGI1 is involved in cell-matrix interactions but suggest that its expression is not relevant in glial cells, implying that its role as a tumor suppressor in gliomas should be reconsidered.
Abstract: PURPOSE: To discuss the results obtained by giving adjuvant treatment for childhood ependymoma (EPD) at relapse after complete surgery only. METHODS AND MATERIALS: Between 1993 and 2002, 63 children older than 3 years old entered the first Italian Association for Pediatric Hematology and Oncology protocol for EPD (group A), and another 14 patients were referred after relapsing after more tumor excisions only (group B). Prognostic factors were homogeneously matched in the two groups. We report on the outcome of group B. RESULTS: Mean time to first local progression in group B had been 14 months. Tumors originated in the posterior fossa (PF) in 10 children and were supratentorial (ST) in 4; 11 had first been completely excised (NED) and 3 had residual disease (ED). Diagnoses were classic EPD in 9 patients, anaplastic in 5. Eight children were referred NED and 6 ED after two or more operations, 5 had cranial nerve palsy, 1 had recurrent meningitis, and 2 had persistent hydrocephalus. All received radiotherapy (RT) to tumor bed and 5 also had pre-RT chemotherapy. Six of 14 patients (6/10 with PF tumors) had a further relapse a mean 6 months after the last surgery; 4 of 6 died: progression-free survival and overall survival at 4 years after referral were 54.4% and 77%, respectively. Considering only PF tumors and setting time 0 as at the last surgery for group B, progression-free survival and overall survival were 32% and 50% for group B and 52% (p < 0.20)/70% (p < 0.29) for the 46 patients in group A with PF tumors. Local control was 32% in group B and 70.5% in group A (p = 0.02). CONCLUSIONS: Relapsers after surgery only, especially if with PF-EPD, do worse than those treated after first diagnosis; subsequent surgery for tumor relapse has severe neurologic sequelae.
Abstract: Cancer stem-like cells (CSC) could be a novel target for cancer therapy, including dendritic cell (DC) immunotherapy. To address this, we developed experiments aimed at DC targeting of neurospheres (NS) from GL261 glioma cells because neurospheres can be enriched in CSC. We obtained murine neurospheres by growing GL261 cells in epidermal growth factor/basic fibroblast growth factor without serum. GL261-NS recapitulated important features of glioblastoma CSC and expressed higher levels of radial glia stem cell markers than GL261 cells growing under standard conditions (GL261 adherent cells, GL261-AC), as assessed by DNA microarray and real-time PCR. GL261-NS brain gliomas were highly infiltrating and more rapidly lethal than GL261-AC, as evidenced by survival analysis (P < 0.0001), magnetic resonance imaging and histology. DC from the bone marrow of syngeneic mice were then used for immunotherapy of GL261-NS and GL261-AC tumors. Strikingly, DC loaded with GL261-NS (DC-NS) cured 80% and 60% of GL261-AC and GL261-NS tumors, respectively (P < 0.0001), whereas DC-AC cured only 50% of GL261-AC tumors (P = 0.0022) and none of the GL261-NS tumors. GL261-NS expressed higher levels of MHC and costimulatory molecules (CD80 and CD86) than GL261-AC; the JAM assay indicated that DC-NS splenocytes had higher lytic activity than DC-AC splenocytes on both GL261-NS and GL261-AC, and immunohistochemistry showed that DC-NS vaccination was associated with robust tumor infiltration by CD8+ and CD4+ T lymphocytes. These findings suggest that DC targeting of CSC provides a higher level of protection against GL261 gliomas, a finding with potential implications for the design of clinical trials based on DC vaccination.
Abstract: Over the last decade, the knowledge on the molecular genetic background of gliomas has dramatically increased. This information provides the basis for the molecular target therapies and molecular tests serve to complement the subjective nature of histopathologic criteria and add useful data regarding response to treatments and prognosis. In particular, the use of loss of heterozygosity (LOH) and methylation specific polymerase chain reaction (PCR) (MSP) based testing of gliomas is already in place and used clinically in several centers. This paper provides a brief overview of these molecular genetic aberrations and discusses the clinical utility, as well as the advantages and disadvantages of such approach.Newly developed molecular techniques, such as LOH testing, fluorescence in situ hybridization (FISH), DNA sequencing and MSP, are currently being employed in assessment of gliomas in some laboratories. However, the clinical use of some markers and the context in which the information obtained should be used are still not entirely understood. Therefore, this paper will focus on validation and implementation of molecular testing in gliomas, with emphasis on LOH on chromosomes 1p, 19q, 17p and 10q and O(6)-methylguanine-DNA methyltransferase (MGMT) methylation status.
Abstract: In recent years, the use of dendritic cells (DC), the most powerful antigen presenting cells, has been proposed for the creation of vaccines against gliomas. This approach has been demonstrated to be safe and non-toxic in phase I or I-II trials (2, 3). Immunotherapy plays a central role in the search for new treatments for glioblastoma multiforme (GBM). In particular, several phase I studies have been performed using DC pulsed by GBM proteins as a vaccine for patients with relapsing GBM. The studies demonstrated that DC vaccination is safe and may produce a significant increase in overall survival. As the first step in the preparation of appropriate conditions for a clinical evaluation in Italy, we have performed pre-clinical experiments on immune-competent mice injected intra-cerebrally with syngeneic GL261GBM cells and treated subcutaneously and intra-tumorally with DC loaded with a GL261 homogenate. These results show that vaccination with DC pulsed with a tumor lysate increases considerably survival in mice bearing intracranial glioblastomas and supports the development of DC-based clinical trials for patients with glioblastomas that do not respond to standard therapies.
Abstract: BACKGROUND: Demyelination in globoid cell leukodystrophy (GLD) is due to a deficiency of galactocerebrosidase (GALC) activity. Up to now, in vivo brain viral gene transfer of GALC showed modest impact on disease development in Twitcher mice, an animal model for GLD. Lentiviral vectors, which are highly efficient to transfer the expression of therapeutic genes in neurons and glial cells, have not been evaluated for direct cerebral therapy in GLD mice. METHODS: Lentiviral vectors containing the untagged cDNA or the hemagglutinin (HA)-tagged cDNA for the full-length mouse GALC sequence were generated and validated in vitro. In vivo therapeutic efficacy of these vectors was evaluated by histology, biochemistry and electrophysiology after transduction of ependymal or subependymal layers in young Twitcher pups. RESULTS: Both GALC lentiviral vectors transduced neurons, oligodendrocytes and astrocytes with efficiencies above 75% and conferred high levels of enzyme activity. GALC accumulated in lysosomes of transduced cells and was also secreted to the extracellular medium. Conditioned GALC medium was able to correct the enzyme deficiency when added to non-transduced Twitcher glial cultures. Mice that received intraventricular injections of GALC vector showed accumulation of GALC in ependymal cells but no diffusion of the enzyme from the ependymal ventricular tree into the cerebral parenchyma. Significant expression of GALC-HA was detected in neuroglioblasts when GALC-HA lentiviral vectors were injected in the subventricular zone of Twitcher mice. Life span and motor conduction in both groups of treated Twitcher mice were not significantly ameliorated. CONCLUSIONS: Lentiviral vectors showed to be efficient for reconstitution of the GALC expression in Twitcher neural cells. GALC was able to accumulate in lysosomes as well as to enter the secretory pathway of lysosomal enzymes, two fundamental aspects for gene therapy of lysosomal storage diseases. Our in vivo results, while showing the capacity of lentiviral vectors to transfer expression of therapeutic GALC in the Twitcher brain, did not limit progression of disease in Twitchers and highlight the need to evaluate other routes of administration.
Abstract: PURPOSE: To delineate clinically relevant molecular signatures of intracranial ependymoma. MATERIALS AND METHODS: We analyzed 24 primary intracranial ependymomas. For genomic profiling, microarray-based comparative genomic hybridization (CGH) was used and results were validated by fluorescent in situ hybridization and loss of heterozygosity mapping. We performed gene expression profiling using microarrays, real-time quantitative reverse transcriptase polymerase chain reaction, and methylation analysis of selected genes. We applied class comparison analyses to compare both genomic and expression profiling data with clinical characteristics. RESULTS: A variable number of genomic imbalances were detected by array CGH, revealing multiple regions of recurrent gain (including 2q23, 7p21, 12p, 13q21.1, and 20p12) and loss (including 5q31, 6q26, 7q36, 15q21.1, 16q24, 17p13.3, 19p13.2, and 22q13.3). An ependymoma-specific gene expression signature was characterized by the concurrent abnormal expression of developmental and differentiation pathways, including NOTCH and sonic hedgehog signaling. We identified specific differentially imbalanced genomic clones and gene expression signatures significantly associated with tumor location, patient age at disease onset, and retrospective risk for relapse. Integrated genomic and expression profiling allowed us to identify genes of which the expression is deregulated in intracranial ependymoma, such as overexpression of the putative proto-oncogene YAP1 (located at 11q22) and downregulation of the SULT4A1 gene (at 22q13.3). CONCLUSION: The present exploratory molecular profiling study allowed us to refine previously reported intervals of genomic imbalance, to identify novel restricted regions of gain and loss, and to identify molecular signatures correlating with various clinical variables. Validation of these results on independent data sets represents the next step before translation into the clinical setting.
Abstract: Mutations and instability of mitochondrial DNA (mtDNA) are frequent in tumors but their pathogenic relevance is not established. To assess their role in the clinical management of malignant gliomas we have studied the D loop of mtDNA in 42 such tumors. Alterations were found in 36% of the cases. The MRI and the clinical follow-up of these patients suggest that these mutations are not associated with increased aggressiveness. mtDNA could be amplified from post-surgical tumor cavities in patients undergoing a loco-regional treatment. These results imply that mtDNA mutations are unlikely to play a role in diagnostic or prognostic evaluations of gliomas: their detection, however, could be of use for the clinical follow-up of malignant gliomas.
Notes: 0167-594X (Print) xD;Comparative Study xD;Journal Article
Abstract: The leucine-rich, glioma inactivated gene 1 (LGI1) gene on human chromosome 10q24 was first identified as a candidate tumor suppressor gene for glioma. Surprisingly, mutations in LGI1 were also shown to cause an idiopathic epilepsy syndrome, autosomal dominant lateral temporal lobe epilepsy (ADLTE). LGI1 is one of the only two currently known non-ion channel genes whose mutations cause idiopathic epilepsy in humans. In this review we summarize the current data on structure and function of the LGI1 protein and discuss clinical aspects of ADLTE and their correlation with LGI1. We also propose that the evidence supporting the tumor suppressor role of LGI1 in malignant gliomas is weak and that further work is necessary to establish LGI1 role in glial cells.
Abstract: During their growth, malignant gliomas interact with the immune system and are able to escape immune reactions. Attempts to instruct the immune system to develop anti-glioma reactions have been partly unsuccessful. Recent advances in the molecular and cellular biology of dendritic cells (DC), however, may increase the chances of preparing effective "vaccines" against these tumours. We show that vaccination with DC pulsed with a tumour lysate considerably increases survival in mice bearing intracranial glioblastomas. These results support the development of DC-based clinical trials for patients with glioblastomas that do not respond to standard therapies.
Abstract: Twenty-two recurrent GBM patients were enrolled for second tumor debulking with local positioning of a Rickam reservoir, in order to locally deliver chemotherapy with the aim of controlling local tumor recurrence. We designed a protocol using systemic temozolomide (150 mg/sqm days 1-5 every 28) in association with mitoxantrone, delivered through the reservoir (4 mg/day 1-5 every 28) positioned into the area of tumor exeresis. After re-operation a residual tumor mass no larger than 2 cm was identified in 18/22 patients. The patients were treated with monthly cycles of chemotherapy until evolution of the tumor, but in no case for more than 10 cycles. Responses were evaluated by MRI scans performed every 2 months and images assessed according to MacDonald's criteria. Response rate: no complete responses (CR), 5 partial responses (PR), 13 stable disease (SD) and 4 progressive disease (PD) occurred. The median progression-free survival (PFS) and survival time (ST) of the whole group of treated patients was 7 and 11 months, respectively and more than a quarter of the patients survived over 18 months. During the study, the patients' compliance was complete and no dropouts occurred. Hematological toxicity was mild and after repeated local injections only minor neurological side-effects occurred. Despite some bias in patients' selection not excluded in this pilot study, results are interesting: the PFS was as long as the survival of recurrent GBM reported in the literature.
Notes: 0167-594X (Print) xD;Comparative Study xD;Journal Article
Abstract: L-2-hydroxyglutaric aciduria is a rare metabolic encephalopathy displaying a subcortical leukoencephalopathy on MRI. Diagnosis rests on detection of an abnormal accumulation of L-2-hydroxyglutaric acid in body fluids. The authors report on four patients who developed a malignant brain tumor during the course of the disease. This association points to a possible role of L-2-hydroxyglutaric aciduria in predisposing to brain tumorigenesis.
Abstract: Pediatric brain tumors may originate from cells endowed with neural stem/precursor cell properties, growing in vitro as neurospheres. We have found that these cells can also be present in adult brain tumors and form highly infiltrating gliomas in the brain of immunodeficient mice. Neurospheres were grown from three adult brain tumors and two pediatric gliomas. Differentiation of the neurospheres from one adult glioblastoma decreased nestin expression and increased that of glial and neuronal markers. Loss of heterozygosity of 10q and 9p was present in the original glioblastoma, in the neurospheres and in tumors grown into mice, suggesting that PTEN and CDKN2A alterations are key genetic events in tumor initiating cells with neural precursor properties.
Abstract: In order to look for genetic markers helpful for the biological risk stratification of medulloblastomas (MBs) we assayed by real-time PCR expression levels of the following genes: MATH1, encoding a critical transcription factor for the differentiation of cerebellar granular cells (CGCs); PEDF, that encodes a trophic factor for CGCs and is located in a region of frequent allelic imbalance in MBs; and BIRC5, encoding the antiapoptotic protein survivin, usually overexpressed in malignancies. Expression levels of TRKC, higher in MBs with a more favorable prognosis, were also studied. Twenty-three patients were considered: MATH1 expression was strong in 14/23 and undetectable in the others. PEDF was up-regulated in 8/23, TRKC in 9/23, and BIRC5 in 23/23. MATH1 expression was significantly correlated with adult age (p < 0.0001), tumor location in hemispheres rather than the vermis (p < 0.0004), and PEDF and TRKC up-regulation (p < 0.008 and p < 0.04, respectively). During development MATH1 is selectively expressed in the external germinal layer (EGL) of the cerebellum. Thus, MATH1 expression identifies a subgroup of MBs that derive from the EGL and arise during adult age into cerebellar hemispheres. MATH1 mRNA-positive MBs express high levels of PEDF and show a trend towards longer survival, in agreement with increased expression of TRKC. BIRC5 expression, which is strong in all MBs and absent in normal cerebellum, lacks any prognostic value but could be explored for selective targeting of therapeutic factors to MBs.
Abstract: Alterations of 19q13 are frequently observed in glial neoplasms, suggesting that this region harbors at least one gene involved in gliomagenesis. Following our previous studies on structural 19q chromosome rearrangements in gliomas, we have undertaken a detailed FISH analysis of the breakpoints and identified a 19q13.2 intrachromosomal amplification of the MAP/microtubule affinity-regulating kinase 4 (MARK4) gene in three primary glioblastoma cell lines. Recent data suggest that this gene is involved in the Wnt-signaling pathway. We observed that the expression of the alternatively spliced MARK4L isoform is upregulated in both fresh and cultured gliomas and overexpressed in all of the above three glioblastoma cell lines. Interestingly, we also found that MARK4L expression is restricted to undifferentiated neural progenitor cells or proliferating glial precursor cells, whereas its expression is downregulated during glial differentiation. Perturbation of expression using antisense oligonucleotides against MARK4 in glioblastoma cell lines, consistently induced a decreased proliferation of tumor cells. Taken together, these data show that MARK4, which is normally expressed in neural progenitors, is re-expressed in gliomas and may become a key target of intrachromosomal amplification upon 19q rearrangements.
Abstract: Stem cells of different origin are under careful scrutiny as potential new tools for the treatment of several neurological diseases. The major focus of these reaserches have been neurodegenerative disorders, such as Huntington Chorea or Parkinson Disease (Shihabuddin et al., 1999). More recently attention has been devoted to their use for brain repair after stroke (Savitz et al., 2002). In this review we will focus on the potential of stem cell treatments for glioblastoma multiforme (Holland, 2000), the most aggressive primary brain tumor, and globoid cell leukodystrophy (Krabbe disease), a metabolic disorder of the white matter (Berger et al., 2001). These two diseases may offer a paradigm of what the stem cell approach may offer in term of treatment, alone or in combination with other therapeutic approaches. Two kinds of stem cells will be consideredhere: neural stem cells and hematopoietic stem cells, both obtained after birth. The review will focus on experimental models, with an eye on clinical perspectives.
Abstract: Retroviral-mediated gene transfer of the IL-4 gene into experimental gliomas can cause tumor rejection, supporting the clinical use of this form of gene therapy for glioblastomas (GBM). In a clinical setting, the administration of dexamethasone (dex) is a standard procedure for GBM patients. This led us to examine the effects of dex on IL-4 gene therapy. We injected intracranially Fischer 344 rats with phosphate-buffered saline, 9L gliosarcoma cells mixed with E86.L4SN(200) cells (retroviral producer cells, RPC, transducing IL-4 cDNA) and 9L cells mixed with PA317.STK.SBA cells (control RPC expressing the HSV-tk gene). The rats from each group were treated with 0, 50, 100 or 250 microg dex/kg/day released by osmotic pumps implanted subcutaneously. While 80-100% of rats receiving 9L cells mixed with IL-4 RPC and not treated by dex survived for at least 2 months following tumor injection, only 50% and 17% of rats receiving 50 or 100 microg/kg/day of dex, respectively, reached this time point. These results indicate that dex significantly diminished the anti-tumor effect of IL-4. Thus, in a clinical setting, IL-4 gene transfer should be performed when low levels of dex are administered or in the absence of dex.
Abstract: Herpes simplex virus thymidine kinase (HSV-TK) is widely used in gene therapy. The enzymatic activity of HSV-TK may be traced in vivo by specific radiopharmaceuticals in order to image transgene expression. However, most of these radiopharmaceuticals are toxic per se or after activation by HSV-TK, and therefore do not represent ideal molecules for clinical applications and repeated imaging. Unlike human cytosolic TK, HSV-TK is not enantioselective and can efficiently phosphorylate both D and L enantiomers of beta-thymidine. Here we show that, after phosphorylation by HSV-TK, tritiated L-beta-thymidine (LT) is selectively retained inside the cells in vitro and in vivo. We used the in vivo accumulation of radioactive phosphorylated LT to image the HSV-TK-positive cells inside a transplantable murine brain tumour after inoculation of cells producing retroviruses carrying HSV-TK. Owing to their unnatural enantiomeric conformation, phosphorylated LT metabolites are very poorly processed by mammalian enzymes, thus leading to increased cellular retention and minimal toxicity. The ability to image cells expressing the HSV-TK gene by using radiolabelled LT, without damaging the cells accumulating the phosphorylated L-nucleoside, will be important to monitor the levels and spatial distribution of therapeutic vectors carrying HSV-TK.
Abstract: The identification of novel therapeutic agents for the management of malignant gliomas represents an area of active research. Here, we show that Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl; TPL), a stable nitroxide free radical, inhibits the growth of C6 glioma cells both in vitro and in vivo. Morphological features of apoptosis were apparent in C6 cells following in vitro treatment with TPL. Cell death was preceded by dose-dependent increase in p21(WAF1/CIP1) expression, without apparent stabilisation of the TP53 gene product. When C6 cells were grown as xenografts in nude mice, treatment with TPL induced a significant dose-dependent decrease in tumour growth, without signs of general or organ toxicity. Tumours from treated mice showed an increase in the number of apoptotic cells and a decrease in the rate of neo-vascularisation compared with tumours from control mice. Our findings suggest a potential use for TPL as a novel antiproliferative agent for the treatment of malignant gliomas.
Abstract: BACKGROUND: Many studies found only a small fragment of the large T-antigen coding sequences in human tumors, raising doubts on authenticity of SV40 sequences detected in these samples. METHODS: Five different regions of SV40 DNA were investigated in 106 fresh human tumor biopsies (25 brain, 69 bone, 12 Wilms' tumors), 71 tumor-derived cell cultures (38 from brain and 33 from bone tumors) and normal tissues (5 fresh bone biopsies and 38 buffy coats) by polymerase chain reaction (PCR) techniques and filter hybridization with specific oligoprobes. Expression of SV40 Tag sequences was analyzed in human tumor specimens by RT-PCR. RESULTS: SV40 large T-antigen sequences were detected at high prevalence, in human biopsies of primary brain (37-44%) and bone (21-37%) tumors, in cell cultures derived from brain (30-54%) and bone (53-80%) tumors. SV40 Tag sequences were detected in 29% of buffy coats of blood donors. However, only four brain tumor cell lines showed all the five regions of the SV40 genome investigated. Expression of SV40 Tag sequences was found in 11 of 27 (41%) human tumor samples. DNA sequence analysis indicated that the PCR-amplified products belong to the SV40 wild type. Polymerase chain reaction products of Tag middle portion from 20 of 78 (26%) samples showed a 97% homology with telomeric sequences of human chromosomes 10 and 11. CONCLUSIONS: Authentic SV40 sequences were detected in human samples. The expression of SV40 Tag sequences indicates that SV40 could play a role, as a cofactor, in the onset/progression of specific human cancers. The inability to detect some regions of the virus genome may suggest that those regions are not required for tumor persistence or growth and have been lost or, alternatively, may be the result of assay conditions that were unable to PCR-amplify those regions in the tumors.
Abstract: Mxi1 is a Mad family member that plays a role in cell proliferation and differentiation. To test the role of Mxi1 on tumorigenesis of glioma cells we transfected a CMV-driven MXI1 cDNA in U87 human glioblastoma cells. Two clones were isolated expressing MXI1 levels 18- and 3.5-fold higher than wild-type U87 cells (clone U87.Mxi1.14 and U87.Mxi1.22, respectively). In vivo, U87.Mxi1.14 cells were not tumorigenic in nude mice and delayed development of tumours was observed with U87.Mxi1.22 cells. In vitro, the proliferation rate was partially and strongly inhibited in U87.Mxi1.22 and U87.Mxi1.14 cells respectively. The cell cycle analysis revealed a relevant accumulation of U87.Mxi1.14 cells in the G(2)/M phase. Interestingly, the expression of cyclin B1 was inhibited to about 60% in U87.Mxi1.14 cells. This inhibition occurs at the transcriptional level and depends, at least in part, on the E-box present on the cyclin B1 promoter. Consistent with this, the endogenous Mxi1 binds this E-box in vitro. Thus, our findings indicate that Mxi1 can act as a tumour suppressor in human glioblastomas through a molecular mechanism involving the transcriptional down-regulation of cyclin B1 gene expression.
Abstract: Oligoastrocytomas are mixed gliomas harboring different genetic alterations and with heterogeneous clinical evolution. We have looked for correlations between genetic losses and clinical evolution in 34 oligoastrocytomas. Loss of heterozygosity (LOH) with different microsatellite markers was studied on chromosomes 1p, 10q, 17p, and 19q. LOH on 1p was found in 44% of the tumors, on 10q in 24%, on 17p in 18%, and on 19q in 38%. LOH on 1p and 19q was combined in 29% of the patients. LOH on 1p was associated with significantly longer overall survival (p = 0.0092) and LOH on 10q with shorter overall survival (p = 0.0206). The observation that LOH on 10q predicts a short survival in oligoastrocytomas is novel and provides further evidence that genetic analysis may help to predict the clinical evolution of different gliomas, giving a more rationale basis to therapeutic options.
Abstract: To study the role of cytokines that are relevant in cancer cachexia syndrome due to intracerebral tumours, mice were injected with human A431 epidermoid carcinoma, OVCAR3 ovarian carcinoma and GBLF glioma cells comparing intracerebral (i.c.) and systemic (i.p. or s.c.) routes of implantation. Anorexia and weight loss developed within 7-10 days in mice injected i.c. with A431 or OVCAR3 cells well before a large tumour developed, while i.c.-injected GBLF cells did not induce cachexia until day 20, when the tumour was large. By contrast, mice injected i.p. or s.c. developed tumours without evidence of anorexia. Thus, intracerebrally-growing A431 and OVCAR3 resulted in cancer cachexia independent of tumour mass, and we investigated their cytokine pattern. Serum levels of murine and human cytokines are not predictive of cancer cachexia development. Reverse-transcriptase polymerase chain reaction (RT-PCR) analysis revealed in the brain of i.c.-injected A431 tumour-bearing mice expression of human interleukin-(IL-)1alpha, IL-1beta and LIF in all samples and IL-6 in two of four samples while in i.c.-injected OVCAR3 tumour-bearing animals IL-6, and LIF were detected in all samples and tumour necrosis factor-alpha (TNFalpha) in two of four samples. Only LIF was expressed in brains of mice injected with GBLF cells. Murine IL-6 was increased only in the brains of A431-bearing mice. Only mice injected i.c. simultaneously with a monoclonal antibody (mAb) directed against the murine IL-6 receptor and OVCAR3 cells, but not those with mAb and A431 cells, showed a significant increase in survival time with a partial and temporary attenuation of cachexia symptoms. These results suggest that IL-6 in OVCAR3 model may be important cachectogenic factor when centrally released by even a limited number of tumour cells.
Abstract: Previous uncontrolled clinical trials have shown the in vivo retrovirus (RV)-mediated transduction of glioblastoma cells with the herpes simplex virus thymidine kinase (HSV-tk) gene and subsequent systemic treatment with ganciclovir to be feasible and well tolerated. However, because of continued tumor progression in most patients, the antitumor effect could not be determined using historical controls. Here, we describe a phase III, multicenter, randomized, open-label, parallel-group, controlled trial of the technique in the treatment of 248 patients with newly diagnosed, previously untreated glioblastoma multiforme (GBM). Patients received, in equal numbers, either standard therapy (surgical resection and radiotherapy) or standard therapy plus adjuvant gene therapy during surgery. Progression-free median survival in the gene therapy group was 180 days compared with 183 days in control subjects. Median survival was 365 versus 354 days, and 12-month survival rates were 50 versus 55% in the gene therapy and control groups, respectively. These differences were not significant. Therefore, the adjuvant treatment improved neither time to tumor progression nor overall survival time, although the feasibility and good biosafety profile of this gene therapy strategy were further supported. The failure of this specific protocol may be due mainly to the presumably poor rate of delivery of the HSV-tk gene to tumor cells. In addition, the current mode of manual injection of vector-producing cells with a nonmigratory fibroblast phenotype limits the distribution of these cells and the released replication-deficient RV vectors to the immediate vicinity of the needle track. Further evaluation of the RV-mediated gene therapy strategy must incorporate refinements such as improved delivery of vectors and transgenes to the tumor cells, noninvasive in vivo assessment of transduction rates, and improved delivery of the prodrug across the blood-brain and blood-tumor barrier to the transduced tumor cells.
Abstract: The lack of expression of the putative tumor suppressor gene DMBT1 has been described in gliomas, lung carcinomas, and other malignancies. To investigate the mechanisms regulating DMBT1 expression we have screened a human genomic library with a 5' cDNA probe and identified a fragment of approximately 3 kb upstream of the proposed coding sequence of DMBT1. This fragment contains subregions that may up- or down-regulate the expression of a reporter gene. These findings may help to elucidate the mechanisms regulating the alternative splicing and the tissue specific expression of DMBT1.
Abstract: We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.
Abstract: Glioblastomas, the most frequent and malignant of primary brain tumors, have a very poor prognosis. Gene therapy of glioblastomas is limited by the short survival of viral vectors and by their difficulty in reaching glioblastoma cells infiltrating the brain parenchyma. Neural stem/progenitor cells can be engineered to produce therapeutic molecules and have the potential to overcome these limitations because they may travel along the white matter, like neoplastic cells, and engraft stably into the brain. Retrovirus-mediated transfer of the gene for interleukin-4 is an effective treatment for rat brain glioblastomas. Here, we transferred the gene for interleukin-4 into C57BL6J mouse primary neural progenitor cells and injected those cells into established syngeneic brain glioblastomas. This led to the survival of most tumor-bearing mice. We obtained similar results by implanting immortalized neural progenitor cells derived from Sprague-Dawley rats into C6 glioblastomas. We also documented by magnetic resonance imaging the progressive disappearance of large tumors, and detected 5-bromodeoxyuridine-labeled progenitor cells several weeks after the injection. These findings support a new approach for gene therapy of brain tumors, based on the grafting of neural stem cells producing therapeutic molecules.
Abstract: OBJECT: Interleukin-12 (IL- 12) has potential for the treatment of tumors because it can stimulate an antitumor immune response and possesses antiangiogenic properties. In the study reported here, the authors investigated the therapeutic role of locally delivered IL-12 in a malignant brain tumor model. METHODS: After genetically engineering 9L gliosarcoma cells to express IL-12 (9L-IL12 cells), the authors used these cells as a source of locally delivered cytokine. First, they investigated the behavior of these cells, which were implanted with the aid of stereotactic guidance into the rat brain, by using serial magnetic resonance imaging and histopathological examination. Second, they assessed the antitumor efficacy of proliferating, as well as nonproliferating (irradiated), 9L-IL12 cells by implanting these cells in animals challenged by wild-type 9L gliosarcoma (9Lwt) cells. The IL-12 expression in brain regions injected with 9L-IL12 was confirmed by reverse transcription-polymerase chain reaction. Last, the authors explored whether animals treated with 9L-IL12 cells developed an antitumor immunological memory by rechallenging the survivors with a second injection of 9Lwt cells. The authors demonstrated that local delivery of IL-12 into the rat brain by genetically engineered cells significantly prolongs survival time in animals challenged intracranially with a malignant glioma. CONCLUSIONS: These findings support continued efforts to refine local delivery systems of IL-12 in an attempt to bring this therapy to clinical trials.
Abstract: Gene therapy approaches to the treatment of experimental cancer are usually based on established neoplastic cell lines which are manipulated in vitro and subsequently transplanted in host animals. However, the relevance of these artificial models to the biology and therapy of human tumors is uncertain. We have previously validated an experimental model based on MMTV-neu transgenic mice in which breast tumors arise spontaneously in 100% of animals and have many features in common with their human counterpart, including the involvement of the neu oncogene and the ability to metastatize. In this article we report the effect of intratumoral, retrovirus-mediated, IL-4 expression on the growth of breast tumors arising in these mice. The size of IL-4 inoculated tumors on the right side was significantly smaller than that of controlateral untreated tumors, suggesting a local effect of IL-4. In addition, the non-injected tumors on the left side of treated animals were significantly smaller than those arising in control transgenic mice, suggesting that IL-4 can also inhibit tumor growth systemically. These findings suggest that IL-4 gene transfer can significantly reduce the growth rate of spontaneously arising breast tumors and that immune-based gene therapy could efficiently complement other approaches based on different mechanisms, such as suicide gene transfer or antisense technology.
Abstract: The PTEN gene, which encodes a tumor suppressor with phosphatase activity, is located on chromosome 10q23 and is mutated in different tumors, including glioblastomas (GBM). We found evidence for a PTEN-related sequence (PTEN-rs) on genomic DNA of GBM and non-neoplastic cells. PTEN-rs does not contain introns and presents several conserved missense mutations, including a T to G transversion at the initiation codon. Rsa I digestion may help to identify this putative PTEN pseudogene which, according to RT-PCR analysis on glioma, fibroblast, brain and lung cells, does not appear to be transcribed.
Abstract: Overexpression of interleukin 4 (IL-4) can impair the tumorigenicity of glioma cells, but direct evidence of its antitumor efficacy after in vivo gene transfer into malignant gliomas has not been provided. To test this, we first injected into the brain of Sprague Dawley rats a 1:1 mixture of C6 rat glioblastoma cells and psi2.L4SN20 or E86.L4SN50 retroviral producer cells (RPCs), secreting 20 and 50 ng of IL-4/5 x 10(5) cells/48 h, respectively. Twenty-seven and 56% of rats receiving injections with these low- or medium-level IL-4 RPCs, respectively, survived tumor injection, whereas control rats died in about 1 month. E86.L4SN50 RPCs coinjected with 9L gliosarcoma cells into syngeneic Fischer 344 rats yielded similar results. A novel IL-4 RPC clone expressing higher levels of IL-4, E86.L4SN200, coinjected with 9L cells increased to 75% the fraction of long-term survivors and induced tumor regression in 50% of rats when injected into established 9L gliosarcomas. Cured rats developed an immunological memory because they rejected a challenge of wild-type 9L cells into the contralateral hemisphere. Magnetic resonance imaging was used to monitor 9L and C6 gliomas and gave direct evidence for tumor rejection in treated rats. Immunohistology showed inflammatory infiltrates in IL-4-treated tumors in which CD8+ T lymphocytes were more abundant, although CD4+ T lymphocytes, B lymphocytes, and macrophages were also present. Overall, these findings suggest that IL-4 gene transfer is a new, promising approach for treating malignant gliomas.
Abstract: Loss of genetic material at chromosome 19 is a rather frequent finding in malignant gliomas. Loss of heterozygosity at region 19q13.3 is common in oligodendrogliomas and is also present, together with other genetic alterations on the same chromosome, in glioblastoma multiforme (GBM). Here we describe the results of cytogenetic and fluorescence in situ hybridization analysis on three GBM cell lines in which a series of complex chromosomal rearrangements affecting chromosome 19 were present. These genetic alterations suggest the presence of a common breakpoint at 19q11-12 which may point to the localization of a fragile site and/or to the presence of tumor suppressor gene(s) in the pericentromeric region of chromosome 19.
Abstract: Globoid cell leukodystrophy (GCL or Krabbe disease) is a recessive disease caused by mutations of the lysosomal enzyme galactocerebrosidase (GALC) and twitcher is the murine model of GCL. We have prepared retroviral packaging cell lines to transduce the GALC gene. Retroviral transduction restored GALC activity in GCL fibroblasts and increased such activity to very high levels in immortalized neural progenitor cells (ST14A cells). GALC activity was also normalized in twitcher fibroblasts co-cultured with ST14A cells over-expressing GALC, demonstrating that this enzyme is secreted and can be imported efficiently by GALC-deficient cells. These results give the necessary background to evaluate the therapeutic effect in twitcher of brain grafting of neural progenitor cells engineered to release high levels of GALC.
Abstract: In tumors, gap junctional intercellular communication (GJIC) is usually down-regulated and the expression of connexins, membrane proteins constituting gap junction channels, is often low or altered. GJIC, allowing the intercellular diffusion of ganciclovir (GCV) triphosphate, is also one mediator of the 'bystander effect', the phenomenon by which herpes simplex virus thymidine kinase (HSVtk)-transduced, neoplastic cells kill surrounding HSVtk-negative cells when treated with GCV. We set up experiments to evaluate the effects of retrovirus-mediated in vivo gene transfer of connexin 43 in malignancies with low GJIC capacity. We found that U-87 human glioblastoma cells transfected in vitro by the human Cx43 cDNA grow significantly more slowly than control U-87 cells and lose their tumorigenicity when injected subcutaneously in nude mice. When the Cx43 gene was transduced in vitro in U-87 cells by a retroviral producer cell line (N3.2.ii, titer 1.5 x 10(6) c.f.u./ml) in vivo results were similar. However, only when U-87 cells were co-injected with N3.2.ii cells in nude mice in a 1:5 ratio, a 50% reduction in tumor size was obtained during the first 3 weeks. Moreover the coinjection of U-87 cells with N3.2.ii and SBA cells (a retroviral producer cell line expressing the HSVtk gene), was not able to potentiate the effects of GCV administration, suggesting that Cx43 gene transfer requires more efficient vectors to increase the bystander effect in vivo.
Abstract: A novel tumor suppressor, PTEN/MMAC1, was recently found on chromosome 10q23 and mutations of this gene were described in about 20% of primary glioblastomas (GBM) and 60% of GBM cell lines. To define further the relevance of PTEN/MMAC1 mutations in GBM we investigated by SSCP analysis its coding sequence in 44 gliomas, including 41 GBM, and in 21 short-term cultures (15 GBM and six malignant astrocytomas). Loss of heterozygosity (LOH) at 10q23 was present in at least one marker in the vicinity of the PTEN/MMAC1 locus in 59% of the informative GBM (primary tumors and cell cultures). SSCP variant bands were found in seven primary GBM (17%) and in one short-term GBM culture and sequence analysis confirmed the presence of somatic mutations in all these cases (five missense, one splicing mutation and two small deletions). These data indicate that PTEN/MMAC1 is inactivated in a subset of GBM and suggest that the high mutation frequency previously found in GBM established cell lines reflects culture condition artifacts rather than the true mutation frequency in vivo. Other suppressors, located on chromosome 10q, may also have a critical role in glioma tumorigenesis.
Abstract: A promising strategy in the treatment of malignant gliomas involves the creation of Herpes Simplex Virus-thymidine kinase (HSV-tk) modified tumor cells. Some authors have observed complete tumor regression after ganciclovir (GCV) treatment of established gliomas transduced in vivo by the HSV-tk gene. Yet, further investigations did not confirm completely these results, even if confirmed the therapeutic potential of such a therapy. Using the rat C6 glioblastoma as a model of malignant brain tumor, we investigated the efficacy of in vivo and in vitro transduction of growing brain tumors with the HSV-tk gene, followed by GCV administration. The stereotactic injection into the left striatum of C6 cells mixed with retroviral producer cells and GCV treatment did not improve significantly the animal survival compared to controls. On the contrary, there was a significant prolongation of the survival of rats inoculated with C6 cells engineered in vitro to express the HSV-tk gene. Nevertheless, complete eradication of the tumors was not achieved. We also injected a group of six rats with a mixture of cells expressing the murine Interleukin-4 (IL-4) gene and C6 cells. IL-4 has been shown to produce the regression of experimental brain tumors. Our preliminary experience seems to confirm that hypothesis. Our results indicate that the outcome of HSV-tk gene therapy can be limited not only by low gene transfer but also by insufficient delivery of GCV to tumor cells. Combined strategies, based on contemporary transduction of HSV-tk and IL-4, may enhance the therapeutic perspectives of such a therapy.
Abstract: The growth of U-87 or C6 gliomas co-implanted in nude mice with retroviral producer cells (VPC) expressing the herpes simplex virus-thymidine kinase (HSV-tk) gene is only partially impaired by treatment with ganciclovir (GCV). The effect of GCV is even less evident when C6 and VPC are co-implanted into the rat brain. Furthermore, tumors from C6 cells carrying the HSV-tk gene are not eradicated by GCV, although they remain sensitive to GCV when replated in vitro. These limits of the HSV-tk/GCV system in glioma gene therapy may be due to insufficient gene transfer and/or insufficient delivery of GCV to glioma cells. Combination of HSV-tk and one or more cytokines may improve the antitumor efficacy. Among cytokines, interleukin-4 (IL-4) has already been shown to be active against gliomas. In nude mice, GCV treatment inhibited tumor growth more effectively after co-injection of C6 cells with a mixture of VPC transducing IL-4 and HSV-tk genes than after co-injection with either IL-4 or HSV-tk VPC only. In immunocompetent Sprague-Dawley rats, co-injection of IL-4 VPC and C6 cells was also effective in inhibiting the growth of C6 brain tumors, 38% of the animals surviving for at least 2 months. Furthermore, increased and prolonged antitumor efficacy was obtained by transducing both IL-4 and HSV-tk genes.
Abstract: During the final step of the malignant progression to glioblastoma multiforme (GBM), the most frequent and malignant of primary brain tumors, more than 90% of the cases exhibit loss of genetic material on chromosome 10. We previously identified a 4-cM deletion interval in the 10q24-qter region that is common to all the GBM we have examined. A contig of 20 YACs spanning the 5 Mb of chromosomal DNA in the region has been assembled. Overlaps between YACs have been verified by STS content, fingerprinting analysis, and/or Alu-Alu PCR. The contig contains 17 known microsatellite markers, 15 new STSs derived from the insert ends of YACs, 9 ESTs, and 11 others STSs, for a total of 52 STSs (average marker density 1/100 kb). The physical map of this region will facilitate the search for a candidate tumor-suppressor gene(s) that is inactivated during the information of GBM.
Abstract: The potential of gene therapy strategies for malignant gliomas that are based on retroviral-mediated transfer of a "suicide gene" such as Herpes Simplex Virus-thymidine kinase HSV-tk and subsequent treatment by a prodrug (ganciclovir, for example), has been emphasized by the promising results obtained by several groups. However, further experimental data as well as preliminary clinical results indicate that the low efficiency of retroviral-mediated gene transfer in vivo as well as difficulties for the diffusion of the prodrug inside the tumour mass can limit the efficacy of this form of gene therapy. To achieve a more effective limitation of tumour growth other approaches may be combined with the "suicide gene" strategy and the enhancement of the immunological response to the tumour by cytokine gene transfer is prominent among these approaches. The authors' experiments in nude mice confirm the antineoplastic role of IL-4 and encourage testing the effects of the simultaneous transfer of IL-4 and HSV-tk genes in immunocompetent animals.
Abstract: Mice transgenic for the activated rat neu oncogene under the control of the mouse mammary tumor virus long terminal repeat (MMTV-LTR) (neu+ mice), develop breast tumors in 100% of cases. We have previously reported that double transgenic mice obtained from crossing neu+ mice with mice transgenic for the herpes simplex virus thymidine kinase (HSVtk) gene can be used as a suitable model to test the 'suicide gene' strategy for mammary tumor gene therapy in vivo. In the present study, we evaluated the efficacy of the HSVtk/ganciclovir (GCV) system in the neu+ mice by inoculating cells producing a retroviral vector bearing the HSVtk gene in the mammary tumors on one side of the animals, and comparing their weight with that of the contralateral tumors, after systemic GCV administration. A statistically significant effect of this therapy was clearly seen (P < 0.001) but complete eradication of the tumors could not be achieved. This was not due to the inefficient delivery of GCV, as no HSVtk expression was detected in the residual tumors, but could be related to the low transduction efficiency (< 10%) and to inability of the 'bystander effect' (probably due to the absence of functional gap-junctions among mammary tumor cells) to kill nontransduced neoplastic cells. These data suggest that results obtained by in vivo models using transplanted tumor cell lines as targets for gene therapy might not be immediately transferable to spontaneously arising tumors in animals or humans.
Abstract: The loss of genetic material on chromosome 10q is frequent in different tumors and particularly in malignant gliomas. We analyzed 90 of these tumors and found loss of heterozygosity (LOH) in >90% of the informative loci in glioblastoma multiforme (GBM). Initial studies restricted the common LOH region to 10q24-qter. Subsequently, the study of a pediatric GBM suggested D10S221 and D10S209, respectively, as centromeric and telomeric markers of a 4-cM LOH region. It is interesting to note that, in one subset of cells from this tumor, locus D10S209 seems involved in the allelic imbalance of a larger region, with D10S214 as telomeric marker. This 17-cM region contains the D10S587-D10S216 interval of common deletion recently defined on another set of gliomas.
Abstract: The MXI1 gene encodes a protein interacting with Max, a regulatory factor of the Myc oncogene, and is located on chromosome 10q25, a region showing frequent loss of heterozygosity in malignant gliomas. We have reassessed the coding sequence of MXI1 and found that, at the 3' end, the open reading frame is 28 codons shorter than previously described. We have also found an AAAAC polymorphic repeat (two alleles, 45% heterozygosity) in the 3' non-coding region of the gene. Six anaplastic astrocytomas and nine glioblastomas, the most malignant form of glioma, were informative for this polymorphism. Loss of heterozygosity was demonstrated in all glioblastomas, but not in the remaining tumors.
Abstract: We have investigated the status of the MTS2 gene, encoding the cyclin-dependent kinase (CDK) inhibitor p15, in 32 glioblastomas. Semi-quantitative PCR identified 7 tumors in which the amplified material was 18.6% of controls and 7 in which was 48.0%, suggesting the occurrence of homozygous and hemizygous deletions, respectively. Single strand conformation polymorphism analysis identified one polymorphism but no mutations. We also expressed MTS2 and MTS1, encoding the contiguous and highly homologous CDK inhibitor p16, in U-87 human glioblastoma cells. Both genes, either separately or in combination, inhibit significantly the proliferation rate of U-87 cells but such inhibition is progressively lost. As a whole, the data assign a tumor suppressor role to p15 and confirm homozygous deletions as the favorite mechanism for the inactivation of MTS1 and MTS2 in glioblastomas.
Abstract: Carnitine palmitoyltransferase (CPT) II deficiency is the most common inherited disorder of lipid metabolism affecting skeletal muscle. To facilitate the identification of disease-causing mutations in the CPT II gene (CPT1), we have established the genomic organization of this gene. CPT1 spans approximately 20 kb of 1p32 and is composed of five exons ranging from 81 to 1305 bp. The sequences of the exon--intron boundaries were determined for each exon and conformed to the consensus splice junction sequences. The 5' and 3' untranslated regions in exon 1 and 5, respectively, were also determined, including the polyadenylation signal and the polyadenylation site. The mature transcript is predicted to be 3090 nt in length. CPT1 exons from CPT II-deficient patients were amplified and directly sequenced. Two novel disease-causing mutations were identified and characterized. The first mutation was a C-665-to-A transversion in exon 1 resulting in a proline-to-histidine substitution at residue 50 of the protein (P50H). This amino acid substitution occurs within a leucine-proline motif that is highly conserved in acyltransferases from different species. The mutation was detected in both alleles of patient 05SB of Italian ancestry, and in one allele of patients 11EG, 38PG, and 26FD of Italian, Dutch, and French ancestry, respectively. The second mutation was a rare G-2173-to-A transition in exon 5 causing an aspartic-acid-to-asparagine substitution at amino acid 553 (D553N) and the generation of a new MseI site. The mutation was detected only in one allele of patient 15MB, of Italian ancestry, who was also heterozygous for the common S113L substitution. Transfection experiments in COS cells demonstrated that both mutations drastically depressed the catalytic activity of CPT II. Biochemical characterization of P50H mutant CPT II in cultured cells from patient 05SB showed that the mutation does not affect substrate binding sites. Finally, immunoblot analysis demonstrated that both mutations were associated with markedly reduced steady-state level of the protein, thus indicating decreased stability of the mutant CPT II.
Abstract: Cells expressing the herpes simplex-thymidine kinase (HS-TK) gene as a consequence of retroviral transduction, as well as TK-negative (TK-) bystander cells, can be killed by treatment with ganciclovir (GCV). In vitro, this "bystander effect," has been attributed to metabolic cooperation through gap junctions or to the uptake of apoptotic vesicles. We show that GCV treatment kills TK-negative U-87 glioma cells cocultured with cells that express TK (TK+) but that have lost the capacity for releasing retroviral particles. A photometric enzyme immunoassay identifies histone-associated DNA fragments, typical of apoptosis, in the cytosol of GCV-treated TK+ cells, and apoptotic features are also demonstrated by ultrastructural studies. Northern blot analysis and the reverse transcription polymerase chain reaction (PCR) show that connexin 43, a major constituent of gap junctions, is expressed in TK+ and U-87 cells. The size of U-87 tumors in nude mice subsequently injected with TK+ cells and GCV is not significantly different than in untreated animals; whereas, after injecting 1:1 mixtures of U-87 and TK+ cells, GCV treatment only causes a temporary regression of tumor growth. On the contrary, when the injected mixtures contain PA317.STK.SBA (a retroviral producer cell line that can transduce efficiently the HS-TK gene) and U-87 cells, tumors are destroyed effectively by GCV treatment. Thus, an experimental setting in which U-87 gliomas are matched with cells that are able to express, but not to transduce, the HS-TK gene indicates that the bystander effect kills U-87 cells in vitro by mechanisms associated with apoptotic death. In vivo, this effect is not sufficient to restrain the tumor growth taking place in immunodeficient animals.
Abstract: Electron transfer flavoprotein (ETF) is a heterodimeric enzyme composed of an alpha-subunit and a beta-subunit and contains a single equivalent of FAD per dimer. ETF deficiency can be demonstrated in individuals affected by a severe metabolic disorder, glutaric acidemia type II (GAII). In this study, we have investigated for the first time the molecular basis of beta-ETF deficiency in three GAII patients: two Japanese brothers, P411 and P412, and a third unrelated patient, P485. Molecular analysis of the beta-ETF gene in P411 and P412 demonstrated that both these patients are compound heterozygotes. One allele is carrying a G to A transition at nucleotide 518, causing a missense mutation at codon 164. This point mutation is maternally derived and is not detected in 42 unrelated controls. The other allele carries a G to C transversion at the first nucleotide of the intron donor site, downstream of an exon that is skipped during the splicing event. The sequence analysis of the beta-ETF coding sequence in P485 showed only a C to T transition at nucleotide 488 that causes a Thr154 to Met substitution and the elimination of a HgaI restriction site. HgaI restriction analysis on 63 unrelated controls' genomic DNA demonstrated that the C488T transition identifies a polymorphic site. Finally, transfection of wild-type beta-ETF cDNA into P411 fibroblasts suggests that wild-type beta-ETF cDNA complements the genetic defect and restores the beta-oxidation flux to normal levels.
Abstract: Five intervals in the pericentromeric region of human chromosome 10 have been defined using a panel of somatic cell hybrids carrying portions of the chromosome. The map positions of twelve markers, consisting of four genes and eight anonymous DNA segments, have been localized by assignment to one of the five intervals. Several other markers could be placed in specific intervals by genetic linkage to assigned loci. When previously published data are incorporated, the summary map of the pericentromeric region encompasses thirty-two loci in bands 10p11.2-q11.2.
Abstract: We have studied alterations of the p53 gene in 27 patients with malignant gliomas. Loss of heterozygosity (LOH) was investigated by microsatellite analysis in 23 patients (22 informative) and detected in nine. Exons 5 through 9 were amplified by polymerase chain reaction (PCR) in these nine patients: alterations were found in five cases (three missense mutations, one non-sense mutation, and one putative deletion), while in four the DNA sequence was normal. In the four patients where LOH could not be studied, the p53 sequence from tumor DNA was normal. These results indicate that microsatellite analysis is a convenient tool for LOH detection at the p53 locus and that mutations of the p53 gene are present in only part of the patients with LOH, implying the possibility that another tumor suppressor gene is located in the proximity of the p53 locus.
Abstract: Electron transfer flavoprotein (ETF) is a heterodimer that contains a single equivalent of FAD and accepts electrons from nine flavoprotein dehydrogenases in the mitochondrial matrix. Human ETF was expressed in Escherichia coli using the expression vector previously employed to express Paracoccus denitrificans ETF (Bedzyk, L. A., Escudero, K. W., Gill, R. E., Griffin, K. J., and Frerman, F. E. (1993) J. Biol. Chem. 268, 20211-20217). cDNAs encoding the beta and alpha subunits of the human protein were inserted into the vector, mimicking the arrangement of the P. denitrificans genes in which coding sequences are joined by overlapping termination and initiation codons. A human ETF containing 30% P. denitrificans sequence at the amino terminus of the beta subunit was also expressed and purified. This chimeric ETF has 64% sequence identity with the human sequence in the substituted region. Kinetic constants of medium chain and short chain acyl-CoA dehydrogenases for the chimeric ETFs were slightly changed from those of human ETF; but, there are marked differences in the kinetic constants of sarcosine dehydrogenase and electron transfer flavoprotein-ubiquinone oxidoreductase with the two ETFs. Absorption spectra of the three redox states of human, chimeric, and P. denitrificans ETF flavins are identical. However, the flavin circular dichroism spectra of the three ETFs are characteristic for each species. The spectrum of the chimeric ETF has both human and P. denitrificans ETF features. The amplitude of the 436 nm band is identical to that of the of the human ETF flavin, but the amplitude of the 375 nm band is identical to that of the P. denitrificans ETF flavin. Thus, flavin in the chimeric ETF appears to be exposed to dipoles in the protein framework provided by human and bacterial sequences. These spectral data indicate that the flavin is located in the vicinity of the amino-terminal region of the beta subunit. The kinetic data suggest that the amino-terminal region of the beta subunit comprises part of the docking site for some primary dehydrogenases and electron transfer flavoprotein-ubiquinone oxidoreductase.
Notes: 0021-9258 (Print) xD;Journal Article xD;Research Support, U.S. Gov't, P.H.S.
Abstract: The CDKN2 gene encodes p16, a protein controlling the cell cycle. CDKN2 is deleted in a relevant number of tumor cell lines, but results of the studies in primary tumors are contradictory. We have investigated by using quantitative polymerase chain reaction and single-strand conformation polymorphism analysis the structure of exon 2 of CDKN2 in 32 malignant gliomas. In 11 tumors the amount of amplified material was 21% of that of controls and in 8 tumors it was 42.3%, suggesting the presence of homozygous and hemizygous deletions of the CDKN2 gene, respectively. However, no abnormality could be detected by single-strand conformation polymorphism analysis. The data confirm in primary gliomas that homozygous deletions are a mechanism of CDKN2 inactivation and suggest that another gene in the vicinity could be targeted by mutations.
Abstract: We have identified two partially overlapping genomic clones that contain part of the 5' regulatory region of the human carnitine palmitoyltransferase II gene. The 1.2 kb region upstream the transcription start site, as defined by primer extension experiments, shows promoter activity when inserted upstream of a reporter gene and contains a putative insulin responsive element.
Abstract: We identified two partially overlapping cDNAs containing divergent 5' sequences of human carnitine acetyltransferase (CAT). cDNA lambda SM-1400 extends the sequence of peroxisomal CAT, whereas cDNA lambda SM-1200 creates a new open reading frame encoding a putative mitochondrial leader peptide. An intron is located where sequences diverge, suggesting that mitochondrial, peroxisomal and possibly endoplasmic reticulum CAT mRNAs derive from alternative splicing of the CAT gene.
Abstract: Using a combination of PCR screening of cDNA libraries and reverse transcription PCR, we have cloned three overlapping DNA fragments that encode human carnitine acetyltransferase (CAT), a key enzyme for metabolic pathways involved with the control of the acyl-CoA/CoA ratio in mitochondria, peroxisomes, and endoplasmic reticulum. The resulting cDNA (2436 bp) hybridizes to a mRNA species of approximately 2.9 kb that is particularly abundant in skeletal muscle and encodes a 68-kDa protein containing a peroxisomal targeting signal. The sequence matches those of several tryptic peptides obtained from purified human liver CAT and shows striking similarities with other members of the carnitine/choline acetyltransferase family very distant throughout evolution. CAT cDNA has also been used for fluorescence in situ hybridization on metaphase spreads of human chromosomes, and the corresponding gene, CAT1, has been mapped to chromosome 9q34.1.
Abstract: We studied the karyotypes of eight differentiated gliomas, 19 anaplastic gliomas, and 23 glioblastomas (GBM). Normal stemlines were present in 70% of the differentiated and anaplastic gliomas; abnormalities were mostly characterized by loss of sex chromosomes. In GBM, on the contrary, only 13% of the stemlines were normal and three groups, 45,XO, near-diploid, and near tetraploid, could be identified. The most frequent alterations among GBM were: total or partial loss of chromosome 10 in nine cases, structural abnormalities of chromosome 9 in seven cases, and loss of the Y chromosome in stemline clones of seven cases. Less frequent abnormalities included chromosomes 7, 1, 3, and 19. Our data support the cytogenetic model of gliomas as multi-stage tumors. GBM, in particular, can originate from the evolution of astrocytomas but can also develop de novo. In both cases loss of genetic material on chromosome 10 seems to play a crucial role.
Abstract: We have isolated a cDNA clone which encodes the entire beta-subunit of human electron-transferring flavoprotein (ETF) by screening an expression library from human liver using polyclonal antibodies against porcine ETF. This cDNA encodes a protein of 255 amino-acid residues with a predicted molecular mass of 27,877 Da which shows a high degree of similarity with partial amino-acid sequences obtained from both rat liver and Paracoccus denitrificans beta-ETF. Northern-blot analysis shows that the human beta-ETF mRNA is approximately 1 kb in size and is abundant in liver, heart and skeletal muscle. Incubation with intact mitochondria indicates that the cDNA-encoded beta-ETF polypeptide contains the information necessary to reach the mitochondrial matrix. These data are in agreement with previous experiments suggesting that beta-ETF, unlike the majority of nuclear-encoded mitochondrial matrix proteins, does not have a cleavable leader peptide. Furthermore, when valinomycin is added to the incubation mixture, the import is abolished, thus demonstrating that it is an energy-dependent process. Interestingly, the sequence analysis of beta-ETF protein identifies a 26.3% identity with the Fix A gene product of the nitrogen-fixing bacterium Azorhizobium caulinodans.
Abstract: Deficiency of carnitine palmitoyltransferase II (CPTase II; palmitoyl-CoA:L-carnitine O-palmitoyltransferase, EC 2.3.1.21) is a clinically heterogeneous autosomal recessive disorder of energy metabolism. We studied the molecular basis of CPTase II deficiency in an early-onset patient presenting with hypoketotic hypoglycemia and cardiomyopathy. cDNA and genomic DNA analysis demonstrated that the patient was homozygous for a mutant CPTase II allele (termed ICV), which carried three missense mutations: a G-1203----A transition, predicting a Val-368----Ile substitution (V368I); a C-1992----T transition, predicting an Arg-631----Cys substitution (R631C); and an A-2040----G transition, predicting a Met-647----Val substitution (M647V). Genomic DNA analysis of family members showed that the mutations cosegregated with the disease in the family. However, screening of 59 healthy controls demonstrated that both the V368I and M647V mutations are sequence polymorphisms with allele frequencies of 0.5 and 0.25, respectively. By contrast, the R631C substitution was not detected in 22 normal individuals or in 12 of 14 CPTase II-deficient patients with the adult muscular form. Notably, 2 adult CPTase II-deficient patients were heterozygous for the ICV allele, thus suggesting compound heterozygosity for this and a different mutant allele. The consequences of the three mutations on enzyme activity were investigated by expressing normal and mutated CPTase II cDNAs in COS cells. The R631C substitution drastically depressed the catalytic activity of CPTase II, thus confirming that this is the crucial mutation. Interestingly, the V368I and M647V substitutions, which did not affect enzyme activity alone, exacerbated the effects of the R631C substitution. Biochemical characterization of mutant CPTase II in patient's cells showed that the mutations are associated with (i) severe reduction of Vmax (approximately 90%), (ii) normal apparent Km values, and (iii) decreased protein stability.
Abstract: We have cloned and sequenced a cDNA encoding human liver carnitine palmitoyltransferase (CPTase; palmitoyl-CoA:L-carnitine O-palmitoyltransferase, EC 2.3.1.21), an inner mitochondrial membrane enzyme that plays a major role in the fatty acid oxidation pathway. Mixed oligonucleotide primers whose sequences were deduced from one tryptic peptide obtained from purified CPTase were used in a polymerase chain reaction, allowing the amplification of a 0.12-kilobase fragment of human genomic DNA encoding such a peptide. A 60-base-pair (bp) oligonucleotide synthesized on the basis of the sequence from this fragment was used for the screening of a cDNA library from human liver and hybridized to a cDNA insert of 2255 bp. This cDNA contains an open reading frame of 1974 bp that encodes a protein of 658 amino acid residues including 25 residues of an NH2-terminal leader peptide. The assignment of this open reading frame to human liver CPTase is confirmed by matches to seven different amino acid sequences of tryptic peptides derived from pure human CPTase and by the 82.2% homology with the amino acid sequence of rat CPTase. The NH2-terminal region of CPTase contains a leucine-proline motif that is shared by carnitine acetyl- and octanoyltransferases and by choline acetyltransferase. The gene encoding CPTase was assigned to human chromosome 1, region 1q12-1pter, by hybridization of CPTase cDNA with a DNA panel of 19 human-hamster somatic cell hybrids.
Abstract: A DNA fragment of 219 bp was obtained by polymerase chain reaction (PCR) on human genomic DNA using two oligonucleotide mixtures derived from peptide sequences of human placenta choline acetyltransferase (ChAT) and from partially conserved amino acid sequences of rat, porcine and Drosophila ChAT. Sequence homology with porcine ChAT demonstrated that this fragment is part of the human ChAT gene. This gene was assigned to chromosome 10 by hybridization of the 219 bp DNA probe with DNA from human-hamster somatic cell hybrids, and to region 10q11.2-10qter by PCR experiments.
Abstract: Carnitine palmitoyl-transferase has been extracted with 0.5% Tween-20 from human liver homogenate and purified to homogeneity. The purified enzyme has a native Mr of 274 kDa. The subunit Mr is of 66 kDa, as shown by SDS-PAGE and immunoblots obtained with antibodies raised against human CPT. Purified CPT shows high affinity for palmitoyl-CoA and palmitoyl-carnitine and is not inhibited by malonyl-CoA. Seven tryptic peptides and the N-terminal of purified human CPT have been sequenced, and found homologous to rat CPT sequence. Both antibodies and peptide sequences are important tools for the investigation of the molecular basis of CPT deficiency in man.
Abstract: Carnitine acetyltransferase was purified from the supernatant obtained after centrifugation of human liver homogenate to a final specific activity of 78.75 unit.mg-1 with acetyl-CoA as a substrate. Human carnitine acetyltransferase is a monomer of 60.5 kDa with maximum activity in the presence of propionyl-CoA and a pH optimum of 8.7. Apparent Km values for acetyl-CoA are three times lower than for decanoyl-CoA. Km values for L-carnitine in the presence of acetyl-CoA are six times lower than in the presence of decanoyl-CoA. Km values for acetylcarnitine are three times lower than for octanoylcarnitine. The polyclonal antibodies against human carnitine acetyltransferase recognize a 60.5-kDa peptide in the purified preparation of human liver and brain homogenates and in immunoblots of mitochondrial and peroxisomal fractions from human liver. Immunoprecipitation and SDS/PAGE analysis of 35S-labelled proteins produced by human fibroblasts indicate that mitochondrial carnitine acetyltransferase is synthesized as a precursor of 65 kDa. We also purified carnitine acetyltransferase from the pellet obtained after centrifugation of liver homogenate. The pellet was extracted by sonication in the presence of 0.5% Tween 20. The chromatographic procedures for the purification and the kinetic, physical and immunological properties of pellet-extracted carnitine acetyltransferase are similar to those of carnitine acetyltransferase purified from the supernatant of human liver homogenate.
Abstract: Five distinct acyl-CoA dehydrogenases are currently known. These are short, medium, long and 2-methyl-branched-chain acyl-CoA dehydrogenases, and isovaleryl-CoA dehydrogenase. We tested these five acyl-CoA dehydrogenases for their ability to dehydrogenate valproyl-CoA using pure enzyme preparations isolated from rat liver mitochondria. The activities of the pure human short-chain, medium-chain and isovaleryl enzymes purified from post-mortem livers, and a long-chain acyl-CoA dehydrogenase preparation partially purified from placental mitochondria, were also tested. Valproyl-CoA was dehydrogenated at a significant rate (0.167 mumol/min per mg protein) only by rat 2-methyl-branched-chain acyl-CoA dehydrogenase. Human 2-methyl-branched-chain acyl-CoA dehydrogenase has not been purified; therefore, it could not be tested. Since four other human acyl-CoA dehydrogenases did not dehydrogenate isobutyryl-CoA, 2-methylbutyryl-CoA (obligatory intermediates from valine and isoleucine, respectively) nor valproyl-CoA, it is reasonable to assume that valproyl-CoA is dehydrogenated by 2-methyl-branch-chain acyl-CoA dehydrogenase in man as well. We identified 2-propyl-2-pentenoyl-CoA as the reaction product from valproyl-CoA by mass spectral analysis of the acyl moiety. Valproyl-CoA, at 0.3 mM, moderately inhibited human acyl-CoA dehydrogenases with the exception of the long-chain enzyme. 5 mM free valproic acid inhibited the activities of various acyl-CoA dehydrogenases only very weakly.
Abstract: Genetic deficiency of short-chain acyl-coenzyme A (CoA) dehydrogenase activity was demonstrated in cultured fibroblasts from a 2-yr-old female whose early postnatal life was complicated by poor feeding, emesis, and failure to thrive. She demonstrated progressive skeletal muscle weakness and developmental delay. Her plasma total carnitine level (35 nmol/ml) was low-normal, but was esterified to an abnormal degree (55% vs. control of less than 10%). Her skeletal muscle total carnitine level was low (7.6 nmol/mg protein vs. control of 14 +/- 2 nmol/mg protein) and was 75% esterified. Mild lipid deposition was noted in type I muscle fibers. Fibroblasts from this patient had 50% of control levels of acyl-CoA dehydrogenase activity towards butyryl-CoA as substrate at a concentration of 50 muM in a fluorometric assay based on the reduction of electron transfer flavoprotein. All of this residual activity was inhibited by an antibody against medium-chain acyl-CoA dehydrogenase. These data demonstrated that medium-chain acyl-CoA dehydrogenase accounted for 50% of the activity towards the short-chain substrate, butyryl-CoA, under these conditions, but that antibody against that enzyme could be used to unmask the specific and virtually complete deficiency of short-chain acyl-CoA dehydrogenase in this patient. Fibroblasts from her parents had intermediate levels of activity towards butyryl-CoA, consistent with the autosomal recessive inheritance of this metabolic defect.
Abstract: cDNAs encoding the precursor of the alpha-subunit of human electron transfer flavoprotein (p alpha-ETF) were cloned and sequenced. The cDNAs span 1,300 base pairs and include the entire coding region of 333 amino acids. The identity of the p alpha-ETF clones was confirmed by hybrid selected translation, by transcription/translation of a cDNA, and by mitochondrial processing of the protein produced by these translations. The identity of the cDNA clones was further confirmed by matching the amino acid sequence deduced from the nucleotide sequence of the cDNAs to amino acid sequences determined from seven tryptic peptides prepared from purified rat alpha-subunit of electron transfer flavoprotein (alpha-ETF). Ninety-eight of 105 amino acids from these rat alpha-ETF tryptic peptides matched with those deduced from the human cDNAs. The seven amino acid substitutions are presumably due to species difference. The calculated molecular weight of the human alpha-ETF precursor was 35,084. The amino-terminal amino acid of the mature protein could not be determined by amino-terminal sequencing, presumably due to blockage and, therefore, an accurate molecular weight of mature alpha-ETF could not be calculated. The molecular sizes of the precursor and mature alpha-ETF have been estimated to be 35 and 32 kDa, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Abstract: We have characterized the abnormalities of glucose metabolism associated with Friedreich's ataxia (FA) by studying plasma glucose, insulin, growth hormone (GH), and glucagon before and after an oral glucose tolerance test (OGTT), an IV glucose load, and an IV arginine load, in 21 patients and in controls. Twelve patients were normotolerant (NT) to glucose, five glucose-intolerant (IT), and four diabetic (DM). Insulin secretion of IT patients was increased and delayed during OGTT. Interestingly, the insulin release during arginine load was significantly decreased in NT and IT as well as in DM patients. The GH response to OGTT was altered in IT patients. Plasma glucagon after an arginine load was significantly higher in patients than in controls. The results indicate that FA is associated with insulin resistance, beta-cell deficiency, and type I diabetes. These alterations might be genetically linked or metabolically related to the primary defect in FA. Their interplay or independent effects are responsible for abnormalities of glucose metabolism in FA.
Abstract: cDNA encoding the precursor of rat liver medium chain acyl-CoA dehydrogenase (EC 1.3.99.3) was cloned and sequenced. The longest cDNA insert isolated was 1866 bases in length. This cDNA encodes the entire protein of 421-amino acids including a 25-amino acid leader peptide and a 396-amino acid mature polypeptide. The identity of the medium chain acyl-CoA dehydrogenase clone was confirmed by matching the amino acid sequence predicted from the cDNA to the NH2-terminal and nine internal tryptic peptide sequences derived from pure rat liver medium chain acyl-CoA dehydrogenase. The calculated molecular masses of the precursor medium chain acyl-CoA dehydrogenase, the mature medium chain acyl-CoA dehydrogenase, and the leader peptide are 46,600, 43,700, and 2,900 daltons, respectively. The leader peptide contains five basic amino acids and only one acidic amino acid; thus, it is positively charged, overall. Cysteine residues are unevenly distributed in the mature portion of the protein; five of six are found within the NH2-terminal half of the polypeptide. Comparison of medium chain acyl-CoA dehydrogenase sequence to other flavoproteins and enzymes which act on coenzyme A ester substrates did not lead to unambiguous identification of a possible FAD-binding site nor a coenzyme A-binding domain. The sequencing of other homologous acyl-CoA dehydrogenases will be informative in this regard.
Abstract: Short chain acyl-CoA (SCA), medium chain acyl-CoA (MCA), and isovaleryl-CoA (IV) dehydrogenases were purified to homogeneity from human liver using ammonium sulfate fractionation followed by DEAE-Sephadex A-50, hydroxyapatite, Matrex Gel Blue A, agarose-hexane-CoA, and Bio-Gel A-0.5 column chromatographies. The specific activities of the final preparations were enriched 507-, 750-, and 588-fold over those from the second ammonium sulfate fractionation step. The native molecular weights were estimated to be 168,000, 178,000, and 172,000, respectively, by gel filtration. Each of them exhibited, on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, a single protein band with molecular weights of 41,000, 44,000, and 42,000, respectively, indicating a homotetrameric structure. UV/visual spectra, fluorescence spectra, and other evidence indicated that each contains 1 mol of FAD per subunit. They all utilized electron transfer flavoprotein (ETF) or phenazine methosulfate (PMS) as an electron acceptor. The products of SCA dehydrogenase/butyryl-CoA, MCA dehydrogenase/octanoyl-CoA, and IV dehydrogenase/isovaleryl-CoA reactions were identified as crotonyl-CoA, 2-octenoyl-CoA, and 3-methylcrotonyl-CoA, respectively, using gas chromatography. Kinetic parameters Vappmax and Kappm) of these enzymes for various acyl-CoA substrates, as well as Kappm values for ETF and PMS are presented. In general, the substrate specificities of human SCA, MCA, and IV dehydrogenases are slightly less stringent than those of their rat counterparts and resemble those of their bovine and porcine counterparts. The pattern of substrate specificity for these enzymes determined using ETF as electron acceptor significantly differed from that determined using PMS. All of them were severely inhibited by (methylenecyclopropyl)acetyl-CoA.
Abstract: Glutamate dehydrogenase (GDH) activity was 68% of control values in leukocyte homogenates of 11 patients with dominant olivopontocerebellar atrophies (OPCA) and 46% in muscle mitochondria of 4 patients with dominant OPCA. In three patients with recessive OPCA and in one sporadic patient, muscle GDH was lower than in controls. However, muscle GDH activity was normal in one of two dominant patients in the same family and decreased in the other, and patients' activities overlapped with lower control values. Plasma glutamate levels were significantly higher in dominant patients than in controls after glutamate challenge. GDH activity may be partially altered at the mitochondrial level in a subgroup of OPCA patients.
Abstract: Dehydrogenation of (2S)-[3-13C]isobutyryl-CoA was carried out in vitro using 2-methyl-branched-chain acyl-CoA dehydrogenase purified from rat liver mitochondria. The product was subsequently hydrated by the addition of bovine crotonase. The resulting 3-hydroxyisobutyric acid was predominantly enriched with 13C at the beta-hydroxy position as determined as a methyl ester using electron ionization-gas chromatography-mass spectroscopy. This finding indicates that isobutyryl-CoA is dehydrogenated stereospecifically at the (pro-2S)-methyl and alpha-methine groups to form methacrylyl-CoA, which is later hydrated with the addition of hydrogen on the same side of the molecule from which it was subtracted to produce 3-hydroxyisobutyryl-CoA.
Notes: 0006-3002 (Print) xD;Journal Article xD;Research Support, U.S. Gov't, P.H.S.
Abstract: Nine patients with hypertrophic cardiomyopathy associated with Friedreich's ataxia were treated with the calcium antagonist verapamil, which is known to reduce myocardial hypertrophy and improve diastolic function in patients with idiopathic hypertrophic cardiomyopathy. Daily oral doses of 7 mg/kg were given for a mean (SD) of 24 (8) months. M mode echocardiography performed at the start of the study and at the end of follow up showed no significant difference between the treated group and an untreated control group of nine patients. Verapamil produced no changes in left ventricular wall thickness, mass index, left ventricular internal diameter, fractional shortening, peak normalised lengthening rate, peak rate of septal and posterior wall thinning, and time from minimum ventricular cavity dimension to mitral valve opening. Myocardial calcium overload has been suggested as a cause of cardiac disease in Friedreich's ataxia; however, verapamil had no beneficial effect on these patients with established myocardial hypertrophy.
Abstract: Brainstem auditory-evoked responses (BAER) and behavior audiometry were evaluated on 18 patients with Friedreich ataxia. Behavior audiometry showed a normal pure tone test, normal performance intensity and phonetically balanced functions in all patients. BAER were abnormal in all patients. The data obtained show a good correlation between BAER and clinical picture and suggest that BAER could be useful in monitoring the clinical condition of FA patients.
Abstract: A therapeutic trial with two different lecithins, with 32 and 7% phosphatidylcholine respectively, was performed for 3 months on 11 patients with clinical diagnosis of dominant, recessive and sporadic olivopontocerebellar atrophies. The correlation between plasma choline levels and the clinical picture shows a clinical worsening with very high choline levels and a slight improvement with smaller increases of plasma choline levels. The possible role in these disorders of phosphatidylcholine and linoleic acid - both present in lecithin - is discussed, with relationship to these findings.
Abstract: Electromyographic examination and studies of motor and sensory conduction velocities were performed in 11 patients with a presumptive diagnosis of olivopontocerebellar atrophy with autosomal dominant transmission. Peripheral nervous system involvement was shown in eight. In two patients with early onset of disease, electrophysiological alterations clearly pointed to severe axonal degeneration, whereas in six they were compatible with slight demyelination.
Abstract: A 20-year-old woman had systemic carnitine deficiency. Biochemical studies of cultured fibroblasts, skeletal muscle mitochondria, and fluids showed no evidence of other disease that might deplete tissue carnitine stores. Carnitine supplementation produced a dramatic improvement in her clinical condition: she gained weight and strength and recovered brain function, which had deteriorated slightly after repeated episodes of encephalopathy. Lipid droplets disappeared from skeletal muscle and plasma, and muscle carnitine content rose from low to normal values. On treatment, she excreted less carnitine than controls. This form of systemic carnitine deficiency may be due to defective carnitine biosynthesis.
