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)

The DNA methylation status of the metastasis-associated S100A4 gene in S100A4-positive and -negative human colon adenocarcinoma cell lines was examined. Northern and Western blot analyses revealed that HT-29, SW480, SW620, WiDr and Colo201 cells expressed S100A4, whereas SW837, LoVo and DLD-1 cells expressed little S100A4. Using CpG methylation-sensitive and -insensitive restriction enzymes and PCR-based methylation assay, it was found that the S100A4 gene in HT-29, SW480, SW620, WiDr and Colo201 cells, but not in SW837, LoVo and DLD-1 cells, was hypomethylated and that the hypomethylation of the second intron was correlated well with the expression of S100A4. 5-Aza-2'-deoxycytidine, an inhibitor of the eukaryotic DNA methyltransferase, induced the expression of the S100A4 gene in SW837, LoVo and DLD-1 cells, while it showed no effect on the expression of the gene in WiDr cells. These results indicate that hypomethylation of the S100A4 gene results in the expression of the gene in colon adenocarcinoma cells.
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PMID:Hypomethylation of the metastasis-associated S100A4 gene correlates with gene activation in human colon adenocarcinoma cell lines. 1009 42

A marked difference exists in the inducibility of inducible NO synthase (iNOS) between humans and rodents. Although important cis and trans factors in the murine and human iNOS promoters have been characterized using episomal-based approaches, a compelling molecular explanation for why human iNOS is resistant to induction has not been reported. In this study we present evidence that the hyporesponsiveness of the human iNOS promoter is based in part on epigenetic silencing, specifically hypermethylation of CpG dinucleotides and histone H3 lysine 9 methylation. Using bisulfite sequencing, we demonstrated that the iNOS promoter was heavily methylated at CpG dinucleotides in a variety of primary human endothelial cells and vascular smooth muscle cells, all of which are notoriously resistant to iNOS induction. In contrast, in human cell types capable of iNOS induction (e.g., A549 pulmonary adenocarcinoma, DLD-1 colon adenocarcinoma, and primary hepatocytes), the iNOS promoter was relatively hypomethylated. Treatment of human cells, such as DLD-1, with a DNA methyltransferase inhibitor (5-azacytidine) induced global and iNOS promoter DNA hypomethylation. Importantly, 5-azacytidine enhanced the cytokine inducibility of iNOS. Using chromatin immunoprecipitation, we found that the human iNOS promoter was basally enriched with di- and trimethylation of H3 lysine 9 in endothelial cells, and this did not change with cytokine addition. This contrasted with the absence of lysine 9 methylation in inducible cell types. Importantly, chromatin immunoprecipitation demonstrated the selective presence of the methyl-CpG-binding transcriptional repressor MeCP2 at the iNOS promoter in endothelial cells. Collectively, our work defines a role for chromatin-based mechanisms in the control of human iNOS gene expression.
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PMID:Epigenetic basis for the transcriptional hyporesponsiveness of the human inducible nitric oxide synthase gene in vascular endothelial cells. 1614 31

The FES locus encodes a unique nonreceptor protein-tyrosine kinase (FES) traditionally viewed as a proto-oncogene but more recently implicated as a tumor suppressor in colorectal cancer (CRC). Recent studies have demonstrated that while FES is expressed in normal colonic epithelium, expression is lost in tumor tissue and colorectal cancer cell lines, a finding common among tumor suppressors. Here we provide compelling evidence that promoter methylation is an important mechanism responsible for downregulation of FES gene expression in colorectal cancer cells. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine resulted in the expression of functional FES transcripts in all CRC cell lines examined, including Caco-2, COLO 320, DLD-1, HCT 116, SNU-1040, SW-480, and HT-29. Bisulfite sequencing of genomic DNA isolated from 5-aza-2'-deoxycytidine-treated HT-29 cells identified methylated CpG dinucleotides immediately upstream from the FES transcription initiation sites. In contrast, this region of the FES promoter was hypomethylated in genomic DNA from normal colonic epithelium. In addition, methylation completely blocked the activity of the FES promoter in reporter gene assays. Promoter methylation is a previously unrecognized mechanism by which FES expression is suppressed in CRC cell lines, and is consistent with a tumor suppressor role for FES in this tumor site despite its tyrosine kinase activity.
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PMID:Promoter methylation blocks FES protein-tyrosine kinase gene expression in colorectal cancer. 1905 25