Cytotoxicity of 5-Aza-2′-deoxycytidine against gastric cancer involves DNA damage in an ATM-P53 dependent signaling pathway and demethylation of P16INK4A
Cytotoxicity of 5-Aza-2′-deoxycytidine against gastric cancer involves DNA damage in an ATM-P53 dependent signaling pathway and demethylation of P16INK4A
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DOI：
10.1016/j.biopha.2012.10.015
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发表时间：
2013-02-01
影响因子：
7.5
通讯作者：
Luo, He-Sheng
中科院分区：
文献类型：
--
作者：
Liu, Juan;Xie, Yi-Shan;Luo, He-Sheng
DNA甲基化抑制剂5-氮杂-2‘-脱氧胞苷(5-aza-2’-deoxcytidine，5-aza-CDR)因其潜在的抗肿瘤作用而日益受到世界各国的关注。然而，细胞毒机制，特别是去甲基化和酶-DNA加合物形成的沉默基因重新激活对5-aza-CDR疗效的相对贡献仍然是一个关键的悬而未决的问题。在这项研究中，我们证明了5-氮杂-镉处理以浓度和时间依赖的方式抑制了胃癌AGS细胞的生长，并导致了DNA损伤反应的G2期停滞。根据PI3K抑制剂Wortmannin阻断5-aza-CDR的细胞毒性作用，以ATM(共济失调-毛细血管扩张突变)依赖的方式检测DNA双链断裂的形成。经5-aza-CDR处理后，ATM的激活与P53在Ser(15)处的磷酸化明显相关，这直接影响了5-aza-cdR修饰的P21(Waf1/Cip1)的表达。进一步的研究发现，P16(Ink4A)去甲基化与DNA甲基转移酶3A和3B的表达显著下调相关，至少部分归因于5-aza-CDR对AGS细胞的细胞毒作用。总之，这些结果极大地增强了我们对5-氮杂-CDR细胞毒性机制的理解，并为评估5-氮杂-CDR改善胃癌患者预后提供了强有力的临床前理论依据。(C)2012年爱思唯尔·马森公司。版权所有。
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. (C) 2012 Elsevier Masson SAS. All rights reserved.