title: Free radical-mediated cytosine C-5 methylation triggers epigenetic changes during carcinogenesis.
abstract: The methylation of the C-5 position of deoxycytidine (dC) in the promoter regions of tumor suppressor genes is often observed in cancer cells. We found that various environmental agents, as well as endogenous compounds such as methionine sulfoxide (MetO), generate methyl radicals and modify dC to form 5-methyl-dC in DNA in vitro. We confirmed that both DNA methylation and cancer incidence in the liver were increased by the administration of MetO to oxidatively stressed mice. In this review, we summarize previous reports on methyl radical generation in vitro and in vivo and DNA modifications by methyl radicals, including our discoveries, as well as our recent experimental evidence suggesting that free radical-mediated dC methylation triggers epigenetic changes.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kasai
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Kawai
authors.forename: Yun-Shan
authors.initials: YS
authors.lastname: Li
mesh_terms: D000818:Animals; D063646:Carcinogenesis / Q000737:chemistry / Q000235:genetics*; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000737:chemistry; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism; D044127:Epigenesis, Genetic; D006801:Humans; D066298:In Vitro Techniques; D008697:Methane / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D004273:DNA, Neoplasm; D003841:Deoxycytidine; C051224:methyl radical; C016569:5-methyldeoxycytidine; D008697:Methane