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Methylation Inhibitor (methylation + inhibitor)
Selected AbstractsAberrant promoter methylation of the TPEF gene in esophageal squamous cell carcinomaDISEASES OF THE ESOPHAGUS, Issue 7 2008B.-J. Zhao SUMMARY., Aberrant methylation of tumor suppressor genes plays an important role in the development of esophageal squamous cell carcinoma (ESCC). The purpose of the present study was to identify the epigenetic changes in ESCC. Methylation-sensitive arbitrarily primed polymerase chain reaction (MS AP-PCR) analysis was used on 22 matched ESCC tumors and adjacent normal tissues. Through this screen we identified a frequently methylated fragment that showed a high homology to the 5,-CpG island of the gene encoding a transmembrane protein containing epidermal growth factor and follistatin domains (TPEF). The methylation status of the TPEF gene was then detected by bisulfite sequencing and the levels of TPEF mRNA were detected by RT-PCR. In addition, the effects of a methylation inhibitor 5-aza-2,-deoxycytidine on TPEF mRNA expression was determined in cells of ESCC cell lines. Hypermethylation of the 5,-CpG island of TPEF was found in 12 of 22 (54.5%) primary tumors. Reverse transcription PCR analysis demonstrated that TPEF mRNA expression was significantly lower in tumors than in adjacent normal tissues, which is associated with promoter hypermethylation. In addition, treatment of ESCC cell lines with 5-aza-2,-deoxycytidine led to re-expression of the TPEF transcript. In conclusion, we observed promoter of TPEF gene is frequently hpermethylated, and is associated with the loss of TPEF mRNA expression in ESCC samples. Promoter hypermethylation of TPEF gene may play a role in the development of ESCC. [source] Aberrant methylation impairs low density lipoprotein receptor-related protein 1B tumor suppressor function in gastric cancerGENES, CHROMOSOMES AND CANCER, Issue 5 2010Yen-Jung Lu DNA methylation plays a significant role in tumor progression. In this study, we used CpG microarray and differential methylation hybridization approaches to identify low density lipoprotein receptor-related protein 1B (LRP1B) as a novel epigenetic target in gastric cancer. LRP1B was hypermethylated in four gastric cancer cell lines, and low LRP1B mRNA expression was associated with high methylation levels in gastric cancer cell lines. Addition of a DNA methylation inhibitor (5-Aza-dC) restored the mRNA expression of LRP1B in these cell lines, indicating that DNA methylation is involved in regulating LRP1B expression. In 45 out of 74 (61%) clinical samples, LRP1B was highly methylated; LRP1B mRNA expression was significantly lower in 15 out of 19 (79%, P < 0.001) gastric tumor tissues than in corresponding adjacent normal tissues. In addition, ectopic expression of mLRP1B4 in gastric cancer cell lines suppressed cell growth, colony formation and tumor formation in nude mice. These results collectively indicate that LRP1B is a functional tumor suppressor gene in gastric cancer and that is regulated by DNA methylation. © 2010 Wiley-Liss,Inc. [source] MAGE-A9 mRNA and protein expression in bladder cancerINTERNATIONAL JOURNAL OF CANCER, Issue 10 2007Valérie Picard Abstract In a previous analysis, we showed that MAGE-As were the most frequently expressed cancer-testis antigens in human bladder tumours. Here, we further characterized by RT-PCR the expression of this family of genes by analyzing specifically MAGE-A3, -A4, -A8 and -A9 mRNAs in 46 bladder tumours and 10 normal urothelia. We found that they were expressed in 30, 33, 56 and 54% of tumours, respectively. Although MAGE-A8 was the most frequent, its expression was low and was also found in most normal urothelia. The other MAGE-A mRNAs were all tumour-specific but MAGE-A9 mRNA was expressed at a higher level and was two times more frequent in superficial than in invasive tumours. To study the expression of the protein, we produced 2 MAGE-A9-specific monoclonal antibodies (mAbs) presenting no cross-reactivity with other MAGE-A proteins. MAb 14A11, was used to analyse the expression of the antigen in testis and tumour samples by immunohistochemistry. In testis, MAGE-A9 expression was restricted to primary spermatocytes. Most bladder tumours that expressed the MAGE-A9 transcript were positive with mAb 14A11. Staining was heterogeneous but half of the tumours showed over 75% positive cells. Finally, we showed that treatment of bladder cancer cells with the methylation inhibitor, 5-aza-2,-deoxycytidine, alone or in combination with the histone deacetylase inhibitors MS-275 and 4-phenylbutyrate could strongly induce the expression of MAGE-A9. These results show that MAGE-A9 is frequently expressed in superficial bladder cancer and could be a relevant target for immunotherapy or chemoimmunotherapy because its expression can be induced by chemotherapeutic drugs. © 2007 Wiley-Liss, Inc. [source] Consistent transcriptional silencing of 35S-driven transgenes in gentianTHE PLANT JOURNAL, Issue 4 2005Kei-ichiro Mishiba Summary In this study, no transgenic gentian (Gentiana triflora × Gentiana scabra) plants produced via Agrobacterium -mediated transformation exhibited transgene (GtMADS, gentian-derived MADS-box genes or sGFP, green fluorescent protein) expression in their leaf tissues, despite the use of constitutive Cauliflower mosaic virus (CaMV) 35S promoter. Strikingly, no expression of the selectable marker gene (bar) used for bialaphos selection was observed. To investigate the possible cause of this drastic transgene silencing, methylation-specific sequences were analysed by bisulfite genomic sequencing using tobacco transformants as a control. Highly methylated cytosine residues of CpG and CpWpG (W contains A or T) sites were distinctively detected in the promoter and 5, coding regions of the transgenes 35S- bar and 35S- GtMADS in all gentian lines analysed. These lines also exhibited various degrees of cytosine methylation in asymmetrical sequences. The methylation frequencies in the other transgene, nopaline synthase (NOS) promoter-driven nptII, and the endogenous GtMADS gene coding region, were much lower and were variable compared with those in the 35S promoter regions. Transgene methylation was observed in the bialaphos-selected transgenic calluses expressing the transgenes, and methylation sequences were distributed preferentially around the as-1 element in the 35S promoter. Calluses derived from leaf tissues of silenced transgenic gentian also exhibited transgene suppression, but expression was recovered by treatment with the methylation inhibitor 5-aza-2,-deoxycytidine (aza-dC). These results indicated that cytosine methylation occurs exclusively in the 35S promoter regions of the expressed transgenes during selection of gentian transformants, causing transcriptional gene silencing. [source] Methylation of the ASC gene promoter is associated with aggressive prostate cancerTHE PROSTATE, Issue 7 2006Rachael L. Collard Abstract Background The aim of this study was to investigate the methylation status of apoptosis-associated speck-like protein containing a CARD (ASC; TMS1; PYCARD) in prostate cancer cell lines and human tissues and to determine if those findings correlate with the clinicopathological features of prostate cancer. Methods Genomic DNA was isolated from prostate cell lines and microdissected tissues, bisulfite converted and analyzed by methylation specific polymerase chain reaction (MSP). Expression of ASC in prostate cancer cell lines treated with or without methylation inhibitors was determined by quantitative or qualitative RT-PCR. Results ASC gene expression was silenced or reduced in five prostate cancer cell lines and correlated with methylation status. Treatment of MDAPCa2b prostate cancer cells with the methylation inhibitors 5-aza-2-deoxycitidine and Zebularine reactivated expression of ASC. Of 58 prostate cancer specimens, methylation of the ASC promoter region was present in 65% of primary cancer tissue, 64% (7/11) of cancer-associated high grade-prostatic intraepithelial neoplasia (HG-PIN), and 28% of normal-appearing but adjacent to tumor prostate tissue. While ASC methylation was not related to Gleason score (P,=,0.46) or pathological stage (P,=,0.75), there was a significantly higher frequency of ASC methylation in the adjacent normal tissue for patients with biochemical recurrence (P,=,0.0383). Conclusions Methylation of the ASC gene promoter is both a frequent and early event in prostate cancer carcinogenesis. Surprisingly, methylation of the adjacent normal tissue occurs significantly more often in patients who later undergo biochemical recurrence, suggesting a role for inactivation of the ASC gene in the initial stages of aggressive disease. Prostate © 2006 Wiley-Liss, Inc. [source] | ||||||||||