title: TSA-induced DNMT1 down-regulation represses hTERT expression via recruiting CTCF into demethylated core promoter region of hTERT in HCT116.
abstract: Trichostatin A (TSA), an inhibitor of histone deacetylase, is a well-known antitumor agent that effectively and selectively induces tumor growth arrest and apoptosis. Recently, it was reported that hTERT is one of the primary targets for TSA-induced apoptosis in cancer cells but the mechanism of which has not yet been elucidated. In the present study, to better understand the epigenetic regulation mechanism responsible for the repression of hTERT by TSA, we examined expression of hTERT in the HCT116 colon cancer cell line after treatment with TSA and performed site-specific CpG methylation analysis of the hTERT promoter. We found that TSA-induced the demethylation of site-specific CpGs on the promoter of hTERT, which was caused by down-regulation of DNA methyltransferase 1 (DNMT1). Among the demethylated region, the 31st-33rd CpGs contained a binding site for CTCF, an inhibitor of hTERT transcription. ChIP analysis revealed that TSA-induced demethylation of the 31st-33rd CpGs promoted CTCF binding on hTERT promoter, leading to repression of hTERT. Taken together, down-regulation of DNMT1 by TSA caused demethylation of a CTCF binding site on the hTERT promoter, the result of which was repression of hTERT via recruitment of CTCF to the promoter.
authors.affiliation: Department of Life Science, College of Natural Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
authors.forename: Jee-Hye
authors.initials: JH
authors.lastname: Choi
authors.forename: Na Young
authors.initials: NY
authors.lastname: Min
authors.forename: Jina
authors.initials: J
authors.lastname: Park
authors.forename: Jin Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Young Jong
authors.initials: YJ
authors.lastname: Ko
authors.forename: Yoonsung
authors.initials: Y
authors.lastname: Kang
authors.forename: Young Joon
authors.initials: YJ
authors.lastname: Moon
authors.forename: Sangmyung
authors.initials: S
authors.lastname: Rhee
authors.forename: Seung Wook
authors.initials: SW
authors.lastname: Ham
authors.forename: Ae Ja
authors.initials: AJ
authors.lastname: Park
authors.forename: Kwang-Ho
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000076246:CCCTC-Binding Factor; D045744:Cell Line, Tumor; D018899:CpG Islands; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism*; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D012097:Repressor Proteins; C012589:trichostatin A; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D019098:Telomerase