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: Neurofibromatosis type 1 (NF1) is a common genetic disease caused by haploinsufficiency of the NF1 tumor-suppressor gene. Different pathogenetic mechanisms have been identified, with the majority (95%) causing intragenic lesions. Single or multiexon NF1 copy number changes occur in about 2% of patients, but little is known about the molecular mechanisms behind these intragenic deletions. We report here on the molecular characterization of a novel NF1 multiexonic deletion. The application of a multidisciplinary approach including multiplex ligation-dependent probe amplification, allelic segregation analysis, and fluorescent in situ hybridization allowed us to map the breakpoints in IVS27b and IVS48. Furthermore, the breakpoint junction was characterized by sequencing. Using bioinformatic analysis, we identified some recombinogenic motifs in close proximity to the centromeric and telomeric breakpoints and predicted the presence of a mutated messenger ribonucleic acid, which was deleted between exons 28 and 48 and encodes a neurofibromin that lacks some domains essential for its function. Through reverse transcriptase-polymerase chain reaction, the expression of the mutated allele was verified, showing the junction between exons 27b and 49 and, as expected, was not subjected to nonsense-mediated decay. Multiexonic deletions represent 2% of NF1 mutations, and until now, the breakpoint has been identified in only a few cases. The fine characterization of multiexonic deletions broadens the mutational repertoire of the NF1 gene, allowing for the identification of different pathogenetic mechanisms causing NF1.
Abstract: Chordomas are rare embryogenetic tumors, arising from remnants of the notochord, characterized by local invasiveness and variable tendency for recurrence. No molecular markers are currently used in a clinical setting to distinguish chordomas with an indolent or an aggressive pattern. Among the genetic lesions observed in this tumor, one of the most commonly detected is 1p loss. In a previous study we observed 1p36 loss of heterozygosity (LOH) in 85% of the analyzed chordomas. We studied a group of 16 homogeneously treated skull base chordomas (SBCs), reporting 1p36 LOH in 75% of them and determining the expression pattern of eight apoptotic genes mapped at 1p36. No tumors shared a common expression profile with nucleus pulposus, which is considered the only adult normal tissue deriving from notochord. In particular, tumor necrosis factor receptor superfamily genes TNFRSF8, TNFRSF9, and TNFRSF14 were differently expressed compared with control in a higher percentage of tumors (40%-53%) than were the remaining analyzed genes, suggesting that the deregulation of these three genes might have a role in chordoma tumorigenesis. The presence/absence of LOH and the expression/nonexpression of each apoptotic gene were studied in a survival analysis. Our results suggest that the lack of 1p36 LOH or the presence of TNFRSF8 expression might be associated with a better prognosis in patients with SBCs.
Abstract: Chordomas are rare neoplasms arising along the axial skeleton. Up to now, the most suitable therapeutic approach is based on a combination of surgical excision and radiotherapy. Chemotherapy in not applied due to its reported low efficacy. Recently, evidence on the efficacy of Imatinib mesylate in two patients has been reported. We analyzed 14 chordoma samples for the expression of the Imatinib mesylate targets by means of RT-PCR and immunohistochemistry and found that PDGFR alpha and PDGFR beta are in some cases expressed in neoplastic cells, while the stromal counterpart of the same tumor shows the above receptors. Findings on the PDGFA/PDGFB expression suggest a receptor-activated status. Our study provides new insights into the specific localization of Imatinib mesylate targets in skull base chordomas that could be taken into account for the setting up of a pharmacological treatment for this tumor.
Abstract: Neurofibromatosis type 1 (NF1) microdeletion syndrome is caused by haploinsufficiency of the NF1 gene and of gene(s) located in adjacent flanking regions. Most of the NF1 deletions originate by nonallelic homologous recombination between repeated sequences (REP-P and -M) mapped to 17q11.2, while a few uncommon deletions show unusual breakpoints. We characterized an uncommon 1.5-Mb deletion of an NF1 patient displaying a mild phenotype. We applied high-resolution FISH analysis allowing us to obtain the sequence of the first junction fragment of an uncommon deletion showing the telomeric breakpoint inside the IVS23a of the NF1 gene. Sequence analysis of the centromeric and telomeric boundaries revealed that the breakpoints were present in the AluJb and AluSx regions, respectively, showing 85% homology. The centromeric breakpoint is localized inside a chi-like element; a few copies of this sequence are also located very close to both breakpoints. The in silico analysis of the breakpoint intervals, aimed at identifying consensus sequences of several motifs usually involved in deletions and translocations, suggests that Alu sequences, probably associated with the chi-like element, might be the only recombinogenic motif directly mediating this large deletion.
Abstract: NF1 microdeletion syndrome is caused by haploinsufficiency of the NF1 gene and of gene(s) located in adjacent flanking regions. Most of the NF1 deletions originate by non-allelic homologous recombination between repeated sequences (REP-P and -M) mapped to 17q11.2, while the remaining deletions show unusual breakpoints. We performed high-resolution FISH analysis of 18 NF1 microdeleted patients with the aims of mapping non-recurrent deletion breakpoints and verifying the presence of additional recombination-prone architectural motifs. This approach allowed us to obtain the sequence of the first junction fragment of an atypical deletion. By conventional FISH, we identified 16 patients with REP-mediated common deletions, and two patients carrying atypical deletions of 1.3 Mb and 3 Mb. Following fibre-FISH, we identified breakpoint regions of 100 kb, which led to the generation of several locus-specific probes restricting the atypical deletion endpoint intervals to a few kilobases. Sequence analysis provided evidence of small blocks of REPs, clustered around the 1.3-Mb deletion breakpoints, probably involved in intrachromatid non-allelic homologous recombination (NAHR), while isolation and sequencing of the 3-Mb deletion junction fragment indicated that a non-homologous end joining (NHEJ) mechanism is implicated.
Abstract: Various cytogenetic and molecular findings indicate 1p36 loss as a consistent change in sporadic and inherited chordoma, a rare embryogenetic neoplasm arising from notochord remnants. We studied 27 sporadic chordomas by means of loss of heterozygosity (LOH) of 31 microsatellites localized to the 1p36.32-36.11 region, and restricted the minimal LOH interval shared by 85% of the tumours to 1p36.13. We also used RT-PCR analysis to investigate the role of the candidate genes CASP9, EPH2A, PAX7, DAN and DVL1, which were selected on the basis of the physical mapping of the LOH region and their plausible oncosuppressor function. RT-PCR analysis showed the presence of DAN and PAX7 transcript fragments of the expected size in all of 8 chordoma samples, whereas the CASP9-specific fragment was observed in only 3 and EPH2A was absent in one. Smaller than expected DVL1 transcripts were found in 4 tumours as well as in their normal counterpart (nucleus pulposus), which also showed a typically sized transcript. Sequencing revealed the skipping of 3 exons in the smallest DVL1 fragment, thus leading to a frameshift and predicting a truncated DVL1 gene product. Our study of the largest cohort of chordoma patients recruited so far indicates a common molecular lesion at 1p36.13, and suggests that the CASP9, EPH2A and DVL1 genes may play an onco-suppressing role and be involved in the development of chordoma.
