Mitchell Cancer Institute University of South Alabama 307 N. University Blvd. MSB 2015 Mobile AL 36688 Tel: 251-460-6993 Fax:251-460-6994 Email: xi@usouthal.edu
Abstract: A number of gene-profiling methodologies have been applied to microRNA research. The diversity of the platforms and analytical methods makes the comparison and integration of cross-platform microRNA profiling data challenging. In this study, we systematically analyze three representative microRNA profiling platforms: Locked Nucleic Acid (LNA) microarray, beads array, and TaqMan quantitative real-time PCR Low Density Array (TLDA).
Abstract: The combined use of several drugs targeting different cellular functions is one approach to achieve tumor control in cancer. We studied the effects of Pseudomonas exotoxin A (PE)-based immunotoxins (ITs), the 9.2.27PE and the 425.3PE, together with 2 different triphenylmethyl derivatives, triphenylmethyl phosphonates and phosphonochloridates (TPMP)-I-2 and 4BI. Combining the triphenylmethyl derivatives with ITs enhanced the cytotoxic effect of the ITs, with TPMP-I-2 in combination with the 425.3PE (targeting the epidermal growth factor receptor) being the most promising combination. The cytotoxicity involving signs of apoptosis was observed in cancer cells from different origins in vitro. It is interesting to note that treatment with IT, TPMP-I-2, or 4BI alone or in combination resulted in strongly decreased protein levels of stearoyl-CoA desaturase. Stearoyl-CoA desaturase is the rate-limiting enzyme for converting saturated fatty acids into monounsaturated fatty acids needed for membrane genesis. Furthermore, the combination of 425.3PE and TPMP-I-2 prolonged the survival time of nude rats in a simulated micrometastatic cervical cancer model. In addition, we demonstrate that a combination of the 425.3PE and 4BI was more effective in reducing tumor growth in a breast cancer model in nude mice compared with either agent alone.
Abstract: Compared with complementary DNA (cDNA) or messenger RNA (mRNA) microarray data, microRNA (miRNA) microarray data are harder to normalize due to the facts that the total number of miRNAs is small, and that the majority of miRNAs usually have low expression levels. In bead-based microarrays, the hybridization is completed in several pools. As a result, the number of miRNAs tested in each pool is even smaller, which poses extra difficulty to intrasample normalization and ultimately affects the quality of the final profiles assembled from various pools. In this article, we consider a measurement error model-based method for bead-based microarray intrasample normalization.
Abstract: We have developed a new approach to systematically study post-transcriptional regulation in a small number of cells. Actively translating mRNAs are associated with polysomes and the newly synthesized peptide chains are closely associated with molecular chaperones such as hsp70s, which assist in the proper folding of nascent polypeptides into higher ordered structures. These chaperones provide an anchor with which to separate actively translating mRNAs associated with polysomes from free mRNAs. Affinity capture beads were developed to capture hsp70 chaperones associated with the polysome complexes. The isolated actively translating mRNAs were used for high-throughput expression profiling analysis. Feasibility was demonstrated using an in vitro translation system with known translationally regulated mRNA transcript thymidylate synthase (TS). We further developed the approach using HCT-116 colon cancer cells with both TS and p53 as positive controls. The steady-state levels of TS and p53 mRNAs were unaltered after 5-fluorouracil treatment as assessed by real-time qRT-PCR analysis. In contrast, the protein expression and polysome-associated mRNA levels of both genes were increased. These differences in translational rate were revealed with our new approach from 500 cells. This technology has the potential to make investigation of translational control feasible with limited quantities of clinical specimens.
Abstract: The growth of cancer cells as multicellular spheroids has frequently been reported to mimic the in vivo tumour architecture and physiology and has been utilized to study antitumour drugs. In order to determine the distinctive characteristics of the spheroid-derived cells compared to the corresponding monolayer-derived cells, we enriched multicellular spheroid-forming subpopulations of cells from three human breast cancer cell lines (MCF7, MCF10AT and MCF10DCIS.com). These spheroid-derived cells were injected into female athymic nude mice to assess their tumorigenic potential and were profiled for their characteristic miRNA signature. We discovered that the spheroid-derived cells expressed increased levels of osteopontin (OPN), an oncogenic protein that has been clinically correlated with increased tumour burden and adverse prognosis in patients with breast cancer metastasis. Our studies further show that increased OPN levels are brought about in part, by decreased levels of hsa-mir-299-5p in the spheroid-forming population from all three cell lines. Moreover, the spheroid-forming cells can organize into vascular structures in response to nutritional limitation; these structures recapitulate a vascular phenotype by the expression of endothelial markers CD31, Angiopoeitin-1 and Endoglin. In this study, we have validated that hsa-mir-299-5p targets OPN; de novo expression of OPN in turn plays a critical role in enhancing proliferation, tumorigenicity and the ability to display vasculogenic mimicry of the spheroid-forming cells.
Abstract: Paclitaxel (Taxol) is an effective chemotherapeutic agent for treatment of cancer patients. Despite impressive initial clinical responses, the majority of patients eventually develop some degree of resistance to Taxol-based therapy. The mechanisms underlying cancer cells resistance to Taxol are not fully understood. MicroRNA (miRNA) has emerged to play important roles in tumorigenesis and drug resistance. However, the interaction between the development of Taxol resistance and miRNA has not been previously explored. In this study we utilized a miRNA array to compare the differentially expressed miRNAs in Taxol-resistant and their Taxol-sensitive parental cells. We verified that miR-125b, miR-221, miR-222, and miR-923 were up-regulated in Taxol-resistant cancer cells by real-time PCR. We further investigated the role and mechanisms of miR-125b in Taxol resistance. We found that miR-125b was up-regulated in Taxol-resistant cells, causing a marked inhibition of Taxol-induced cytotoxicity and apoptosis and a subsequent increase in the resistance to Taxol in cancer cells. Moreover, we demonstrated that the pro-apoptotic Bcl-2 antagonist killer 1 (Bak1) is a direct target of miR-125b. Down-regulation of Bak1 suppressed Taxol-induced apoptosis and led to an increased resistance to Taxol. Restoring Bak1 expression by either miR-125b inhibitor or re-expression of Bak1 in miR-125b-overexpressing cells recovered Taxol sensitivity, overcoming miR-125-mediated Taxol resistance. Taken together, our data strongly support a central role for miR-125b in conferring Taxol resistance through the suppression of Bak1 expression. This finding has important implications in the development of targeted therapeutics for overcoming Taxol resistance in a number of different tumor histologies.
Abstract: Melanoma is a highly aggressive and deadly skin cancer. Early intervention correlates with nearly 100% patient survival, but greater than 80% mortality is associated with advanced disease. Currently, few treatment options are available for patients with metastatic melanoma, and the global incidence of melanoma is increasing faster than that of other cancers. Therefore, it is vitally important to uncover and use genetic and epigenetic regulatory mechanisms at work during the development and progression of melanoma for better prevention, diagnosis, and clinical management. MicroRNA (miRNA) is a set of small, single-stranded, noncoding RNAs that target the 3'-untranslated region of an estimated 30% of all human genes to inhibit their expression. Our understanding of miRNA-mediated regulation of cancers has grown immensely over the past decade. Here we review currently available data on melanoma-associated miRNAs, highlighting those deregulated miRNAs targeting important genes and signaling pathways involved in the progression of melanocytes to primary and metastatic melanoma. Understanding the important roles of miRNAs in melanoma progression and metastasis development will contribute to the development of miRNA-targeted therapy in the future.
Abstract: MicroRNA (miRNA) is a set of newly discovered non-coding small RNA molecules. Its significant effects have contributed to a number of critical biological events including cell proliferation, apoptosis development, as well as tumorigenesis. High-dimensional genomic discovery platforms (e.g. microarray) have been employed to evaluate the important roles of miRNAs by analyzing their expression profiling. However, because of the small total number of miRNAs and the absence of well-known endogenous controls, the traditional normalization methods for messenger RNA (mRNA) profiling analysis could not offer a suitable solution for miRNA analysis. The need for the establishment of new adaptive methods has come to the forefront.
Abstract: In osteosarcoma, aggressive preoperative and postoperative multidrug chemotherapy given to all patients has improved patient survival rate to the present level of approximately 60%. However, no tumor marker is available that reliably can identify those patients who will or will not respond to chemotherapy.
Abstract: The exact cellular and molecular mechanisms involved in melanoma tumorigenesis remain obscure. Previous gene expression profiling analyses performed upon NHEM and human melanoma samples identified WFDC1 as one of the most frequently down-regulated genes. Here we further showed that NHEM readily express WFDC1 but expression is reduced or completely lost in 80% of the patients-derived melanoma cell lines and tissue samples examined. Furthermore, we show that promoter hypermethylation accounts for the silencing of the WFDC1 gene in 20% of the melanoma cell lines examined. The over-expression of WFDC1 in two metastatic melanoma cell lines, A375 and LOX, resulted in a significant delay of tumor growth in a murine xenograft model, despite a non-significant difference in tumor cell growth in vitro. Gene expression microarray analysis and further expression validation suggests that the Dickkopf-1 (Dkk1) gene is up-regulated in WFDC1 over-expressing cell lines, suggesting that the tumor suppressive function of WFDC1 may be partially a result of up-regulated Dkk1 gene expression, which is known to be a potent inhibitor of the Wnt signaling pathway.
Abstract: We found that the expression levels of N-Myc interactor (Nmi) were low in aggressive breast cancer cell lines when compared with less aggressive cell lines. However, the lower levels in the aggressive lines were inducible by interferon-gamma (IFN-gamma). Because Nmi has been reported to be a transcription cofactor that augments IFN-gamma induced transcription activity, we decided to test whether Nmi regulates expression of Dkk1, which is also inducible by IFN-gamma. We established stable clones constitutively expressing Nmi in MDA-MB-231 (breast) and MDA-MB-435 (melanoma) cell lines. Dkk1 was significantly up-regulated in the Nmi expressing clones concurrent with reduced levels of the critical transcription cofactor of Wnt pathway, beta-catenin. Treatment of the Nmi expressors with blocking antibody to Dkk1 restored beta-catenin protein levels. c-Myc is a known downstream target of activated beta-catenin signaling. Treatment of Nmi expressors with the proteosome inhibitor MG132, resulted in elevated beta-catenin levels with concomitant elevation of c-Myc levels. Our functional studies showed that constitutive expression of Nmi reduced the ability of tumor cells for the invasion, anchorage independent growth and tumor growth in vivo. Collectively, the data suggest that overexpression of Nmi inhibits the Wnt/beta-catenin signaling via up-regulation of Dkk1 and retards tumor growth.
Abstract: Recent technological advances in the analysis of the human genome have opened the door to improving our primitive understanding of the gene expression patterns in cancer. For the first time, we have an overview of the complexities of tumorigenesis and metastatic progression of cancer. The examination of the phenotypic and (epi)genetic changes in cutaneous melanoma has identified several genes deemed central to the development and progression of melanoma.
Abstract: Previous studies from our group have shown that the expression levels of Orc6 were highly elevated in colorectal cancer patient specimens and the induction of Orc6 was associated with 5-fluorouracil (5-FU) treatment. The goal of this study was to investigate the molecular and cellular impact of Orc6 in colon cancer. In this study, we use HCT116 (wt-p53) and HCT116 (null-p53) colon cancer cell lines as a model system to investigate the impact of Orc6 on cell proliferation, chemosensitivity and pathways involved with Orc6. We demonstrated that the down regulation of Orc6 sensitizes colon cancer cells to both 5-FU and cisplatin (cis-pt) treatment. Decreased Orc6 expression in HCT-116 (wt-p53) cells by RNA interference triggered cell cycle arrest at G1 phase. Prolonged inhibition of Orc6 expression resulted in multinucleated cells in HCT-116 (wt-p53) cell line. Western immunoblot analysis showed that down regulation of Orc6 induced p21 expression in HCT-116 (wt-p53) cells. The induction of p21 was mediated by increased level of phosphorylated p53 at ser-15. By contrast, there is no elevated expression of p21 in HCT-116 (null-p53) cells. Orc6 down regulation also increased the expression of DNA damaging repair protein GADD45beta and reduced the expression level of JNK1. Orc6 may be a potential novel target for future anti cancer therapeutic development in colon cancer.
Abstract: Malignant tumors comprise a small proportion of cancer-initiating cells (CIC), capable of sustaining tumor formation and growth. CIC are the main potential target for anticancer therapy. However, the identification of molecular therapeutic targets in CIC isolated from primary tumors is an extremely difficult task. Here, we show that after years of passaging under differentiating conditions, glioblastoma, mammary carcinoma, and melanoma cell lines contained a fraction of cells capable of forming spheroids upon in vitro growth under stem cell-like conditions. We found an increased expression of surface markers associated with the stem cell phenotype and of oncogenes in cell lines and clones cultured as spheroids vs. adherent cultures. Also, spheroid-forming cells displayed increased tumorigenicity and an altered pattern of chemosensitivity. Interestingly, also from single retrovirally marked clones, it was possible to isolate cells able to grow as spheroids and associated with increased tumorigenicity. Our findings indicate that short-term selection and propagation of CIC as spheroid cultures from established cancer cell lines, coupled with gene expression profiling, represents a suitable tool to study and therapeutically target CIC: the notion of which genes have been down-regulated during growth under differentiating conditions will help find CIC-associated therapeutic targets.
Abstract: The process of malignant transformation, progression and metastasis of melanoma is poorly understood. Gene expression profiling of human cancer has allowed for a unique insight into the genes that are involved in these processes. Thus, we have attempted to utilize this approach through the analysis of a series of primary, non-metastatic cutaneous tumors and metastatic melanoma samples.
Abstract: Previous studies from our laboratory have identified a number of genes associated with chemosensitivity to 5-fluorouracil (5-FU) using an in vitro colon cancer cell line model. In this study, the in vivo significance of several marker genes in terms of prognostic potential was evaluated using colorectal cancer patient samples. Eight marker genes were selected based on their functional roles and significant fold changes in expression. They are SERTA domain containing 1 (SEI1), ribonucleotide reductase M2 polypeptide (RRM2), origin recognition complex, subunit 6 homolog-like (ORC6L), eukaryotic translation initiation factor 4E (EIF4E), thymidylate synthase (TS), SET and MYND domain containing 3 (SMYD3), Dickkopf homolog 4, and methyl-CpG binding domain protein 4 (MBD4). Forty-eight snap frozen clinical colorectal samples (24 normal and 24 paired colorectal cancer patient samples) were selected with detailed clinical follow-up information. cDNAs were synthesized and the expression levels of marker genes were quantified via qRT-PCR analysis. The statistical significance of these markers for disease prognosis was evaluated using the two-tailed paired Wilcoxon test. Survival curves were plotted according to the method of Kaplan-Meier and compared using the log-rank test. Based on the quantitative expression analysis, RRM2 (p=0.0001; 95% CI, 2.0-4.5), ORC6L (p=0.0001; 95% CI, 1.8-4.6), EIF4E (p=0.0002; 95% CI, 0.3-0.9), TS (p=0.0005; 95% CI, 0.7-2.2) and SMYD3 (p=0.0001; 95% CI, 0.8-1.5) were overexpressed in tumor tissues. However, the expression of SEI1 was decreased in tumors (p=0.02; 95% CI, 0.1-1.3), consistent with the function of SEI1 as a potential tumor suppressor. Kaplan-Meier survival analysis indicated that MBD4 is a significant prognostic factor for patient survival (p=0.03). MBD4 was a key protein involved in DNA methylation. The expression of TS was associated with tumor stage as it had a significantly higher expression level in UICC stage I and II compared to stage IV patients (p=0.03). MBD4 may be a potential novel prognostic marker for predicting patient survival for colorectal cancer.
Abstract: ABSTRACT: BACKGROUND: MRJ, (DNAJB6), a novel member of the human DnaJ family, encodes two isoforms. The smaller isoform, MRJ(S), is studied mainly for a possible role in Huntington's disease. There are no reports about any biological activity of the longer isoform, MRJ(L). We investigated a possible role of this molecule in breast cancer. Our studies were prompted by the interesting observations we made with regard to the expression of MRJ in breast cancer cell lines and breast cancer tissue microarrays as described below. METHODS: Expression MRJ(L) from several breast cancer cell lines was evaluated using real time PCR. Relative levels of the small and large isoforms in breast cancer cell lines were studied using western blot analysis. Breast cancer progression tissue microarray was probed using anti MRJ antibody. MRJ(L) was ectopically expressed in two breast cancer cell lines. These cell lines were evaluated for their in vitro correlates of tumor aggressiveness such as invasion, migration and anchorage independence. The cell lines were also evaluated for in vivo tumor growth and metastasis. The secreted proteome of the MRJ(L) expressors was analyzed to understand the biochemical changes brought about by re-expression of MRJ(L). RESULTS: We found that MRJ(L) is expressed at a significantly lower level in aggressive breast cancer cell lines compared to the normal breast. Further, in clinical cases of breast cancer the expression of MRJ is lost as the grade of infiltrating-ductal carcinoma (IDC) advances. Importantly MRJ staining is lost in those cases that also had lymph node metastasis. We report that MRJ(L) is a protein with a functional nuclear localization sequence. Expression of MRJ(L) via an exogenous promoter in breast cancer cell line MDA-MB-231 and in MDA-MB-435 (a cell line, which metastasizes from the mammary fat pad) decreases their migration, invasion, reduces motility and significantly reduces orthotopic tumor growth in nude mice. Moreover, the secreted proteome of the MRJ(L)-expressing cells showed reduced levels of tumor progression and metastasis promoting secreted proteins, such as osteopontin (SPP1), zinc binding alpha-2-glycoprotein 1 (AZGP1), osteonectin (SPARC), nucleophosmin (NPM1) and VGF nerve growth factor inducible (VGF). On the other hand, the levels of the secreted metastasis-suppressor, KiSS1, were increased in the secreted proteome of the MRJ(L)-expressing cells. We confirmed by qRT-PCR analysis that the secreted profile reflected altered transcription of the respective genes. CONCLUSIONS: Collectively, our data presents an important role of a totally uncharacterized isoform of DNAJB6 in breast cancer. We show that MRJ(L) is a nuclear protein that is lost in breast cancer and regulates several key players in tumor formation and metastasis and is functionally able to retard tumor growth.
Abstract: Various in vitro and in vivo experimental models have been used for the discovery of genes and pathways involved in melanoma and other types of cancer. However, in many cases, the results from various tumor models failed to be validated successfully in clinical studies. Limited information is available on how closely these models reflect the in vivo physiological conditions. In this study, a comprehensive genomics approach was used to systematically compare the expression patterns of snap frozen samples obtained from patients with primary melanoma, lymph node metastasis, and distant metastases, and compare these patterns to those of their corresponding cell lines and tumor xenografts in nude mice. The GE Healthcare 20k human genome array was used and the expression data was normalized and analyzed using GeneSpring 7.2 software. Based on the expression analysis, the correlation rate between the snap frozen primary patient samples vs. derived cell lines was 66%, with 1687 differentially expressed genes. The correlation rate between the snap frozen primary patient samples and the tumor xenografts was 75%, with 1,374 differentially expressed genes, and the correlation rate comparing tumor xenografts to derived cell lines ranged between 58% and 84%. These results demonstrated significant gene expression differences between tumor materials with different in vitro and in vivo growth microenvironments. Such studies can help us to distinguish between genes up- or down-regulated as a result of the microenvironment and those stably expressed independently of the tumor milieu. With the extensive use of cell lines and xenografts in cancer research, the information obtained using our approach may help to better interpret results generated from different tumor models by understanding common differences, as well as similarities at the gene expression level, information that may have important practical and biological implications.
Abstract: Previous studies have shown that cadherin-11 (CDH11) may be involved in the metastatic process of osteosarcoma. The correlation of the expression levels of CDH11 in osteosarcoma samples with the risk of disease progression and metastasis was examined. Real time qRT-PCR was used to quantify CDH11 expression in a set of newly established osteosarcoma cell lines, 11 primaries and five metastases, compared to the levels in 12 normal osteoblast cell lines established from healthy bone, and also in a set of 10 snap-frozen osteosarcoma samples. In all cases long term clinical follow-up data was available. The CDH11 expression level decreased gradually from the osteoblast to the primary cell lines (p=0.2184) and further to those established from the tumor metastases (p=0.0275). Importantly, the level of CDH11 expression correlated significantly (p=0.01) with patient survival (Kaplan-Meier survival analysis) in both sample sets (p=0.0128 for the cell lines, p=0.0492 for the biopsies). In conclusion, the results indicate that CDH11 may be useful as a prognostic marker of disease progression and survival in osteosarcoma.
Abstract: MicroRNAs (miRNAs) are a class of small non-coding RNAs that mediate gene expression at the posttranscriptional and translational levels and have been demonstrated to be involved in diverse biological functions. Mounting evidence in recent years has shown that miRNAs play key roles in tumorigenesis due to abnormal expression of and mutations in miRNAs. High throughput miRNA expression profiling of several major tumor types has identified miRNAs associated with clinical diagnosis and prognosis of cancer treatment. Previously our group has discovered a novel regulatory relationship between tumor suppressor gene p53 with miRNAs expression and a number of miRNA promoters contain putative p53 binding sites. In addition, others have reported that c-myc can mediate a large number of miRNAs expression. In this review, we will emphasize algorithms to identify mRNA targets of miRNAs and the roles of miRNAs in colorectal cancer. In particular, we will discuss a novel regulatory relationship of miRNAs with tumor suppressor p53 and c-myc. miRNAs are becoming promising novel targets and biomarkers for future cancer therapeutic development and clinical molecular diagnosis.
Abstract: microRNAs (miRNAs) are noncoding small RNAs that regulate gene expression at the translational level by mainly interacting with 3' UTRs of their target mRNAs. Archived formalin-fixed paraffin-embedded (FFPE) specimens represent excellent resources for biomarker discovery. Currently there is a lack of systematic analysis on the stability of miRNAs and optimized conditions for expression analysis using FFPE samples. In this study, the expression of miRNAs from FFPE samples was analyzed using high-throughput locked nucleic acid-based miRNA arrays. The effect of formalin fixation on the stability of miRNAs was also investigated using miRNA real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. The stability of miRNAs of archived colorectal cancer FFPE specimens was characterized with samples dating back up to 10 yr. Our results showed that the expression profiles of miRNAs were in good correlation between 1 mug of fresh frozen and 1-5 mug of FFPE samples (correlation coefficient R (2) = 0.86-0.89). Different formalin fixation times did not change the stability of miRNAs based on real-time qRT-PCR analysis. There are no significant differences of representative miRNA expression among 40 colorectal cancer FFPE specimens. This study provides a foundation for miRNA investigation using FFPE samples in cancer and other types of diseases.
Abstract: The T-type Ca2+ channel Cav3.1 subunit is present in pulmonary microvascular endothelial cells (PMVECs), but not in pulmonary artery endothelial cells (PAECs). The present study sought to assess the role of Cav3.1 in thrombin-induced Weibel-Palade body exocytosis and consequent von Willebrand factor (VWF) release. In PMVECs and PAECs transduced with a green fluorescent protein (GFP)-tagged VWF chimera, we examined the real-time dynamics and secretory process of VWF-GFP-containing vesicles in response to thrombin and the cAMP-elevating agent isoproterenol. Whereas thrombin stimulated a progressive decrease in the number of VWF-GFP-containing vesicles in both cell types, isoproterenol only decreased the number of VWF-GFP-containing vesicles in PAECs. In PMVECs, thrombin-induced decrease in the number of VWF-GFP-containing vesicles was nearly abolished by the T-type Ca2+ channel blocker mibefradil as well as by Cav3.1 gene silencing with small hairpin RNA. Expression of recombinant Cav3.1 subunit in PAECs resulted in pronounced increase in thrombin-stimulated Ca2+ entry, which is sensitive to mibefradil. Together, these data indicate that VWF secretion from lung endothelial cells is regulated by two distinct pathways involving Ca2+ or cAMP, and support the hypothesis that activation of Cav3.1 T-type Ca2+ channels in PMVECs provides a unique cytosolic Ca2+ source important for Gq-linked agonist-induced VWF release.
Abstract: Thymidylate synthase (TS) is a critical target for cancer chemotherapy and is one of the most extensively studied biomarkers for fluoropyrimidine-based chemotherapy. In addition to its critical role in enzyme catalysis, TS functions as an RNA binding protein to regulate the expression of its own mRNA translation and other cellular mRNAs, such as p53, at the translational level. In this study, a comprehensive gene expression analysis at the levels of both transcriptional and post-transcriptional regulation was conducted to identify response markers using human genome array with TS-depleted human colon cancer HCT-C18 (TS-) cells and HCT-C18 (TS+) cells stably transfected with the human TS cDNA expression plasmid.
Abstract: BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNAs (~22 nucleotides) that regulate gene expression at a post-transcriptional level via imperfect base pairing to the 3'-UTR of their target mRNAs. Previous studies from our group identified a number of deregulated miRNAs due to the loss of p53 tumor suppressor in colon cancer cell lines. To further investigate the in vivo biological significance of these miRNAs, the expressions of hsa-let-7g, hsa-miR-143, hsa-miR-145, hsa-miR-181b and hsa-miR-200c were investigated using formalin-fixed paraffin-embedded (FFPE) colon cancer specimens to evaluate the potential relationship with chemosensitivity and tumorigenesis. PATIENTS AND METHODS: Forty-six patients with recurrent or residual colon cancer lesions were treated with the 5-fluorouracil-based antimetabolite S-1. This includes twenty-one pairs of tumor and normal samples. Total RNAs were isolated and the expression level of each particular miRNA was quantified using real time qRT-PCR analysis. RESULTS: The expression levels of hsa-let-7g, hsa-miR-181b and hsa-miR-200c were over-expressed in tumor tissues compared to normal tissues. The expression levels of hsa-let-7g (p=0.03; Mann-Whitney test) and hsa-miR-181b (p=0.02; Mann-Whitney test) were strongly associated with clinical response to S-1. Although hsa-let-7g and hsa-miR-181b are strongly associated with patient's response to S-1 treatment, they are not significant prognostic factors for predicting survival. CONCLUSION: hsa-let-7g, hsa-miR-181b and hsa-miR-200c may be associated with tumorigenesis in colon cancer. In addition, hsa-let-7g and hsa-miR-181b may be potential indicators for chemoresponse to S-1 based chemotherapy.
Abstract: The functions of non-coding microRNAs (miRNAs) in tumorigenesis are just beginning to emerge. Previous studies from our laboratory have identified a number of miRNAs that were deregulated in colon cancer cell lines due to the deletion of the p53 tumor suppressor gene. In this study, the in vivo significance of some of these miRNAs was further evaluated using colorectal clinical samples. Ten miRNAs (hsa-let-7b, hsa-let-7g, hsa-miR-15b, hsa-miR-181b, hsa-miR-191, hsa-miR-200c, hsa-miR-26a, hsa-miR-27a, hsa-miR-30a-5p and hsa-miR-30c) were evaluated for their potential prognostic value in colorectal cancer patients. Forty eight snap frozen clinical colorectal samples (24 colorectal cancer and 24 paired normal patient samples) with detailed clinical follow-up information were selected. The expression levels of 10 miRNAs were quantified via qRT-PCR analysis. The statistical significance of these markers for disease prognosis was evaluated using a two tailed paired Wilcoxon test. A Kaplan-Meier survival curve was generated followed by performing a Logrank test. Among the ten miRNAs, hsa-miR-15b (p = 0.0278), hsa-miR-181b (p = 0.0002), hsa-miR-191 (p = 0.0264) and hsa-miR-200c (p = 0.0017) were significantly over-expressed in tumors compared to normal colorectal samples. Kaplan-Meier survival analysis indicated that hsa-miR-200c was significantly associated with patient survival (p = 0.0122). The patients (n = 15) with higher hsa-miR-200c expression had a shorter survival time (median survival = 26 months) compared to patients (n = 9) with lower expression (median survival = 38 months). Sequencing analysis revealed that hsa-miR-181b (p = 0.0098) and hsa-miR-200c (p = 0.0322) expression were strongly associated with the mutation status of the p53 tumor suppressor gene. Some of these miRNAs may function as oncogenes due to their over-expression in tumors. hsa-miR-200c may be a potential novel prognostic factor in colorectal cancer.
Abstract: Previous studies from our laboratory have identified several endothelial cell-associated marker genes implicated in human melanoma metastasis via tumor vasculogenic mimicry. In this study, we used dual model systems composed of melanoma cell lines and clinical melanoma samples to validate the importance of insulin-like growth factor binding protein-3 (IGFBP-3) as a marker involved in disease progression. Gene expression analysis was done using a microarray approach for both primary and metastatic melanoma samples. The expression of IGFBP-3 was decreased using a small interfering RNA (siRNA) knockdown approach and quantified with real-time quantitative reverse transcription-PCR analysis. The expression of insulin-like growth factor binding protein 3 (IGFBP-3) was up-regulated by nearly 16-fold in WM266-4 compared with WM35 cells. A subsequent parallel analysis using freshly isolated primary and metastatic melanoma cell samples and melanoma tissue array confirmed the previous findings. The functional significance of IGFBP-3 in melanoma invasion was further investigated using a siRNA gene knockdown approach, with the expression of IGFBP-3 markedly reduced. Additionally, siRNA knockdown resulted in a significant reduction in cell motility, migration, and invasive capacity of WM266-4 cells in vitro. These results strongly suggest that IGFBP-3 expression may be a vital cell motility, migration, and proliferation factor necessary for melanoma metastasis and is an important biomarker in human melanoma.
Abstract: The aim of this study was to investigate the role of p53 in regulating micro-RNA (miRNA) expression due to its function as a transcription factor. In addition, p53 may also affect other cellular mRNA gene expression at the translational level either via its mediated miRNAs or due to its RNA-binding function.
Abstract: The development of intestinal gastric carcinoma involves several precancerous stages. The environmental factor plays an important role in gastric carcinogenesis, while the host's genetic makeup may influence the susceptibility to cancer. In this study we investigated correlations of the p53 variations at codon 72 and p21(WAF1/CIP1) haplotype with the risk of intestinal gastric carcinoma. Forty-eight intestinal gastric carcinoma cases (GC), 96 chronic atrophic gastritis (CAG), 96 intestinal metaplasia (IM) and 96 dysplasia (DYS) controls were enrolled in this study. The p53 codon 72 proline allele carriers were found to be more susceptible to progress to GC than to IM (OR = 2.22, 95%CI = 1.05-4.70, P = 0.038). Patients carrying homozygous p21(WAF1/CIP1) haplotype A, which contains the serine at codon 31, the cytidine at the 16th base of the second intron, and the cytidine at the 70th base of the exon 3 were more prone to develop GC than to reach the IM or DYS stage (IM versus GC, OR = 3.35, 95%CI = 1.11-10.15; DYS versus GC, OR = 3.27, 95%CI = 1.09-9.80, P = 0.035). The combination of p53 codon 72 variation with the p21(WAF1/CIP1) haplotype further distinguished the risk of GC from IM precancerous lesion (OR = 9.31, 95% CI = 1.77-48.85, P = 0.08). These results suggest that p53 and/or p21(WAF1/CIP1) genotype may influence the progression during gastric tumorigenesis.
Abstract: p21WAF1/CIP1 gene is known for a most important cell cycle regulator as well as its roles in appoptosis and differentiation. This review focuses on p21WAF1/CIP1 gene functions and its association with carcinogenesis. Better understanding of the structure and function of p21WAF1/CIP1 gene may help to comprehend molecular mechanisms of cancers and to facilitate diagnosis and treatment of malignancy.
Abstract: It has recently been suggested that people of the Indian population who carried the codon 149 polymorphism (GAT-->GGT) of P21(Waf1/Cip1) gene were more susceptible to esophageal cancer and oral cancer than the individuals without that polymorphism. Since esophageal cancer is a high incident neoplasm in China, we analysed the same codon of P21(Waf1/Cip1) in the Chinese population. Blood samples from 80 esophageal cancer patients and 80 normal blood donors were collected for DNA extraction. Methods of Polymerase Chain Reaction (PCR) and direct sequencing were used for detection of the polymorphism in codon 149 of P21(Waf1/Cip1). Bioinformatics analysis was also thoroughly performed for this gene. No polymorphism was found in all samples tested. Bioinformatics analysis revealed that the so-called polymorphism of codon 149 reported previously was a wrong one. In conclusion, no polymorphism exists in codon 149 of P21(Waf1/Cip1). It is not appropriate to use it as a susceptible site of the gene in cancer study.
