5-aza-cytidine is a potent inhibitor of DNA methyltransferase 3a and induces apoptosis in HCT-116 colon cancer cells via Gadd45-and p53-dependent mechanisms (Retracted Article)
5-aza-cytidine is a potent inhibitor of DNA methyltransferase 3a and induces apoptosis in HCT-116 colon cancer cells via Gadd45-and p53-dependent mechanisms (Retracted Article)
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DOI：
10.1124/jpet.104.074195
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发表时间：
2005-02-01
影响因子：
3.5
通讯作者：
Gali-Muhtasib, H
中科院分区：
文献类型：
--
作者：
Schneider-Stock, R;Diab-Assef, M;Gali-Muhtasib, H
甲基转移酶抑制剂通常用于临床试验促进肿瘤细胞死亡，但其详细的细胞毒性作用尚未完全了解。对它们的凋亡诱导机制及其与DNA甲基转移酶（DNMT1、DNMT3a和DNMT3b）的相互作用的更深入了解，可能有助于设计出更有效、更低细胞毒性的药物。5-aza-cytidine （5-aza-CR）是一种有效的DNMT1抑制剂，已知可诱导沉默基因的去甲基化和再激活。在本研究中，我们研究了5-aza-CR在结肠癌细胞系HCT-116中凋亡、细胞周期、生长抑制作用对p53的依赖性，以及对DNMT1、DNMT3a、DNMT3b表达水平的影响。暴露于5-aza- cr诱导促进细胞周期阻滞和DNA修复的基因（p21（WAF1）和GADD45）或细胞凋亡（p53、RIPK2、Bak1、caspase 5和caspase 6）上调。同时，抗凋亡Bcl2蛋白和G(2)/ m介质细胞周期蛋白B1下调。与pft - α（一种选择性p53抑制剂）共孵育，恢复了GADD45、Bcl2、cyclin B1和p21（WAF1）的表达水平，几乎完全逆转了5-aza-CR的生长抑制、细胞周期和凋亡作用。5-aza-CR处理导致p16（INK4）表达的全局去甲基化和再激活。DNMT1和DNMT3a mRNA表达明显下降，pft - α逆转了这些影响。然而，5-aza-CR处理并没有调节DNMT3b的表达。我们的数据表明，5-aza-CR在HCT-116中的作用是由p53及其下游效应物p21（WAF1）和GADD45介导的。这是首次报道p53与DNMT1和新生甲基转移酶DNMT3a的调控之间存在联系。
Methyltransferase inhibitors commonly used in clinical trials promote tumor cell death, but their detailed cytotoxic action is not yet fully understood. A deeper knowledge about their apotosis-inducing mechanisms and their interaction with DNA methyltransferases (DNMTs) DNMT1, DNMT3a, and DNMT3b might allow the design of more effective drugs with lower cytotoxicity. 5-aza-cytidine (5-aza-CR), a potent inhibitor of DNMT1, is known to induce demethylation and reactivation of silenced genes. In this study, we investigated the p53 dependence of apoptotic, cell cycle, and growth inhibitory effects of 5-aza-CR, as well as the influence on the expression level of DNMT1, DNMT3a, and DNMT3b in the colon cancer cell line HCT-116. Exposure to 5-aza-CR induced the up-regulation of genes promoting cell cycle arrest and DNA repair (p21(WAF1) and GADD45) or apoptosis (p53, RIPK2, Bak1, caspase 5, and caspase 6). In parallel, there was a down-regulation of antiapoptotic Bcl2 protein and the G(2)/M-mediator cyclin B1. Coincubation with pifithrin-alpha (PFT-alpha), a selective p53 inhibitor, restored GADD45, Bcl2, cyclin B1, and p21(WAF1) expression levels and almost completely reversed the growth inhibitory, cell cycle, and apoptotic effects of 5-aza-CR. 5-aza-CR treatment caused global demethylation and reactivation of p16(INK4) expression. There was a marked decrease in DNMT1 and DNMT3a mRNA expression, with PFT-alpha reversing these effects. However, 5-aza-CR treatment did not modulate DNMT3b expression. Our data demonstrate that 5-aza-CR action in HCT-116 is mediated by p53 and its downstream effectors p21(WAF1) and GADD45. This is the first report to show a link between p53 and regulation of DNMT1 and de novo methyltransferase DNMT3a.