Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.1.1.37 (DNA methyltransferase)
 4,983 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA hypomethylation is one of the major epigenetic alterations in human cancers. We have previously shown that genes identified as hypomethylated in pancreatic cancer are expressed in pancreatic cancer cell lines, but not in normal pancreatic ductal epithelium and can be reexpressed in nonexpressing cells using 'epigenetic modifying agents' such as DNA methyltransferase inhibitors. To identify additional targets for aberrant hypomethylation in pancreatic cancer, we used oligonucleotide microarrays to screen for genes that displayed expression patterns associated with hypomethylation. This analysis identified a substantial number of candidates including previously reported hypomethylated genes. A subset of eight genes were selected for further methylation analysis, and two cancer-related genes, maspin and S100P, were found to be aberrantly hypomethylated in a large fraction of pancreatic cancer cell lines and primary pancreatic carcinomas. Combined treatment with 5-aza-2'-deoxycytidie and trichostatin A resulted in synergistic induction of maspin and S100P mRNA in MiaPaCa2 cells where both genes were methylated. Furthermore, there was an inverse correlation between methylation and mRNA expression level for maspin and S100P in a large panel of pancreatic cancer cell lines. We also found a significant difference in the methylation patterns of maspin and two previously identified hypomethylated genes (trefoil factor 2 and lipocalin 2) between pancreatic and breast cancer cell lines, suggesting cancer-type specificity for some hypomethylation patterns. Thus, our present results confirm that DNA hypomethylation is a frequent epigenetic event in pancreatic cancer, and suggest that gene expression profiling may help to identify potential targets affected by this epigenetic alteration.
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PMID:Identification of maspin and S100P as novel hypomethylation targets in pancreatic cancer using global gene expression profiling. 1471 96

Oligoarray analysis of a matched pair of prostate cancer and normal cell lines derived from the same radical prostatectomy specimen identified 113 candidate hypomethylated genes that were overexpressed in the cancer cells and contained CpG islands. Hypomethylation of wingless-related MMTV integration site 5A (WNT5A), S100 calcium-binding protein P (S100P) and cysteine-rich protein 1(CRIP1) was confirmed in the cancer cells by bisulfite sequencing. Treatment of the corresponding normal prostate epithelial cells 1542-NPTX with the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-aza-CdR) induced higher levels of mRNA expression and partial loss of methylation on these genes. Primary prostate cancers were tested using methylation-specific polymerase chain reaction. WNT5A was hypomethylated in 11/17 (65%) tumors, S100P in 8/16 (50%) and CRIP1 in 13/20 (65%). Bisulfite sequencing of a section of the 5' untranslated region (UTR) of WNT5A revealed that three CpG sites (15, 24 and 35) were consistently methylated (93%) in the normal cell line and normal tissues, but not in the prostate cancer cell line and eight primary prostate cancers. Multiple putative binding sites for the transcription factors SP1 and AP-2 were found adjacent to CpG sites 15 and 24. A putative c-Myb binding site was located within the CpG site 35. Anti-c-Myb antibody co-precipitation with WNT5A was methylation-sensitive in 1542-NPTX cells. It is likely that an epigenetic mechanism regulates WNT5A expression in prostate cancer.
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PMID:Hypomethylation of WNT5A, CRIP1 and S100P in prostate cancer. 1748 81

Epigenetic silencing of gluthathione-S-transferase pi (GSTP1) is recognized as being a molecular hallmark of human prostate cancer. We investigated the effects of green tea polyphenols (GTPs) on GSTP1 re-expression and further elucidated its mechanism of action and long-term safety, compared with nucleoside-analog inhibitor of DNA methyltransferase (DNMT), 5-aza-2'-deoxycitidine. Exposure of human prostate cancer LNCaP cells to 1-10 microg/ml of GTP for 1-7 days caused a concentration- and time-dependent re-expression of GSTP1, which correlated with DNMT1 inhibition. Methyl-specific-PCR and sequencing revealed extensive demethylation in the proximal GSTP1 promoter and regions distal to the transcription factor binding sites. GTP exposure in a time-dependent fashion diminished the mRNA and protein levels of MBD1, MBD4 and MeCP2; HDAC 1-3 and increased the levels of acetylated histone H3 (LysH9/18) and H4. Chromatin immunoprecipitation assays demonstrated that cells treated with GTP have reduced MBD2 association with accessible Sp1 binding sites leading to increased binding and transcriptional activation of the GSTP1 gene. Exposure of cells to GTP did not result in global hypomethylation, as demonstrated by methyl-specific PCR for LINE-1 promoter; rather GTP promotes maintenance of genomic integrity. Furthermore, exposure of cells to GTP did not cause activation of the prometaststic gene S100P, a reverse response noted after exposure of cells to 5-aza-2'deoxycitidine. Our results, for the first time, demonstrate that GTP has dual potential to alter DNA methylation and chromatin modeling, the 2 global epigenetic mechanisms of gene regulation and their lack of toxicity makes them excellent candidates for the chemoprevention of prostate cancer.
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PMID:Promoter demethylation and chromatin remodeling by green tea polyphenols leads to re-expression of GSTP1 in human prostate cancer cells. 1985 14

Cisplatin is among the most widely used cytotoxic anticancer agents in solid tumors; however, the development of secondary resistance remains a major obstacle to clinical efficacy. Treatment-related DNA hypermethylation may play a role in creating drug-resistant phenotypes by inactivating genes that are required for cytotoxicity. We applied a pharmacologic unmasking approach to detect hypermethylated genes whose inactivation contributes to cisplatin resistance. Using three pairs of isogeneic, cisplatin-sensitive, and cisplatin-resistant cell lines derived from two parental cell lines (KB-3-1 and SCC25), we identified several hundred genes that were downregulated in each resistant cell line and reactivated by the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine. Among them, 30 genes were common to two or more cell lines and/or reported to be downregulated in previous studies. Bisulfite sequencing confirmed that 14 genes were hypermethylated in resistant cell lines but not in the sensitive parental cell lines. Six of 14 genes (SAT, C8orf4, LAMB3, TUBB, G0S2, and MCAM) were cisplatin inducible in sensitive but not in resistant cell lines. Small interfering RNA knockdown of two genes, SAT and S100P, increased cell viability with cisplatin treatment in sensitive parental cell lines. S100P knockdown significantly decreased the S-phase fraction of parental sensitive cell lines and slowed cell proliferation, which was associated with decreased sensitivity to cisplatin. Based on these findings, we conclude that DNA methylation is a frequent event in cells that are chronically exposed to cisplatin and that methylation-induced gene silencing may play a role in the development of resistance to cytotoxic chemotherapeutic agents.
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PMID:Identification of hypermethylated genes associated with cisplatin resistance in human cancers. 2021 21