Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2525202 | Biomedicine & Pharmacotherapy | 2013 | 10 Pages |
Abstract
The DNA methylation inhibitor 5-Aza-2â²-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 Ser15, which was directly responsible for 5-Aza-CdR modified P21Waf1/Cip1 expression. Further exploration revealed that demethylation of P16INK4A 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.
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Oncology
Authors
Juan Liu, Yi-Shan Xie, Fu-Liang Wang, Li-Jun Zhang, Yan Zhang, He-Sheng Luo,