title: Cytotoxicity of 5-Aza-2'-deoxycytidine against gastric cancer involves DNA damage in an ATM-P53 dependent signaling pathway and demethylation of P16(INK4A).
abstract: The DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) has increasingly attracted worldwide attention for its antineoplastic potential. The cytotoxitic mechanisms, however, especially, the relative contribution of silenced genes reactivation by demethylation and enzyme-DNA adduct formation to the efficacy of 5-Aza-CdR is still a crucial unresolved question. In this investigation, we demonstrated that 5-Aza-CdR treatment resulted in growth suppression in a concentration and time-dependent manner and G2 phrase arrest - hallmarks of a DNA damage response in gastric cancer AGS cells. Formation of DNA double-strand breaks, as monitored by comet assay was examined in an ATM (ataxia-telangiectasia mutated)-dependent manner based on the fact that PI3K inhibitor Wortmannin abolished the action of cytotoxicity of 5-Aza-CdR. Upon treatment with 5-Aza-CdR, ATM activation was clearly associated with P53 phosphorylation at Ser(15), which was directly responsible for 5-Aza-CdR modified P21(Waf1/Cip1) expression. Further exploration revealed that demethylation of P16(INK4A) correlated with the strikingly down-regulated expressions of DNA methyltransferase 3A as well as 3B was, at least in part, attributed to the cytotoxicity of 5-Aza-CdR in AGS cells. Conclusively, these results greatly enhance our understanding of the mechanisms of cytotoxicity of 5-Aza-CdR and strongly provide the preclinical rationale for an assessment of 5-Aza-CdR to ameliorate patient outcome with gastric cancer.
authors.affiliation: Department of Geriatrics, Renmin Hospital of Wuhan University, Wuchang District, Wuhan, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Liu
authors.forename: Yi-Shan
authors.initials: YS
authors.lastname: Xie
authors.forename: Fu-Liang
authors.initials: FL
authors.lastname: Wang
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: He-Sheng
authors.initials: HS
authors.lastname: Luo
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins; D001374:Azacitidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D020552:Comet Assay; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D000090205:DNA Methyltransferase 3A; D004268:DNA-Binding Proteins / Q000378:metabolism; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000473:pathology; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000077191:Wortmannin; D000097584:DNA Methyltransferase 3B
chemical_list: D000730:Androstadienes; D000964:Antimetabolites, Antineoplastic; D064007:Ataxia Telangiectasia Mutated Proteins; D001374:Azacitidine; D018797:Cell Cycle Proteins; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D004268:DNA-Binding Proteins; D000077209:Decitabine; D017346:Protein Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000077191:Wortmannin; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C576324:ATM protein, human