Nonhomologous end joining is essential for cellular resistance to the novel antitumor agent, β-lapachone
Nonhomologous end joining is essential for cellular resistance to the novel antitumor agent, β-lapachone
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DOI：
10.1158/0008-5472.can-07-0935
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发表时间：
2007-07-15
期刊：
影响因子：
11.2
通讯作者：
Boothman, David A.
中科院分区：
文献类型：
--
作者：
Bentle, Melissa S.;Reinicke, Kathryn E.;Boothman, David A.
常用的抗肿瘤药物，如DNA拓扑异构酶I/II毒药，通过产生不可修复的DNA双链断裂（DSBs）来杀死癌细胞。为了修复dsb，无错误同源重组（HR）和/或易出错的非同源末端连接（NHEJ）被激活。这些过程涉及磷脂酰肌醇3'-激酶相关的丝氨酸/苏氨酸激酶家族：失调性毛细血管扩张突变（ATM），与HR相关的ATM-和rad3，以及与NHEJ相关的dna依赖性蛋白激酶催化亚基（DNA-PKcs）。这些修复过程的改变可能导致药物/辐射耐药性和基因组不稳定性增加。β -lapachone (β -lap，也称为arq501)，目前处于治疗胰腺癌的II期临床试验中，在过度表达NAD(P)H：醌氧化还原酶-1 （NQO1）的癌细胞中引起一种新的caspase和p53非依赖性细胞死亡。NQO1催化β -lap的无效氧化还原，导致活性氧的产生、DNA断裂、γ - h2ax灶的形成和poly（adp -核糖）聚合酶-1的过度活化，这是细胞死亡所必需的。在这里，我们报告了β -lap暴露导致nq01依赖性MRE11-Rad50-Nbs-1复合物的激活。此外，还发现了ATM丝氨酸1981、DNA-PKcs苏氨酸2609和Chk1丝氨酸345磷酸化；表明HR和NHEJ同时激活。然而，通过遗传或化学手段抑制NHEJ，而不是HR，增强了β -lap的致死率。这些研究揭示了β -lap使癌细胞放射增敏的机制，并表明NHEJ是增强P-lap单独或与其他药物联合治疗NQO1水平升高的癌细胞的有效靶点。
Commonly used antitumor agents, such as DNA topoisomerase I/II poisons, kill cancer cells by creating nonrepairable DNA double-strand breaks (DSBs). To repair DSBs, error-free homologous recombination (HR), and/or error-prone nonhomologous end joining (NHEJ) are activated. These processes involve the phosphatidylinositol 3'-kinase-related kinase family of serine/threonine enzymes: ataxia telangiectasia mutated (ATM), ATM- and Rad3-related for HR, and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) for NHEJ. Alterations in these repair processes can cause drug/radiation resistance and increased genomic instability. beta-lapachone (beta-lap; also known as ARQ 501), currently in phase II clinical trials for the treatment of pancreatic cancer causes a novel caspase- and p53-independent cell death in cancer cells overexpressing NAD(P)H:quinone oxidoreductase-1 (NQO1). NQO1 catalyzes a futile oxidoreduction of beta-lap leading to reactive oxygen species generation, DNA breaks, gamma-H2AX foci formation, and hyperactivation of poly(ADP-ribose) polymerase-1, which is required for cell death. Here, we report that beta-lap exposure results in NQ01dependent activation of the MRE11-Rad50-Nbs-1 complex. In addition, ATM serine 1981, DNA-PKcs threonine 2609, and Chk1 serine 345 phosphorylation were noted; indicative of simultaneous HR and NHEJ activation. However, inhibition of NHEJ, but not HR, by genetic or chemical means potentiated beta-lap lethality. These studies give insight into the mechanism by which beta-lap radiosensitizes cancer cells and suggest that NHEJ is a potent target for enhancing the therapeutic efficacy of P-lap alone or in combination with other agents in cancer cells that express elevated NQO1 levels.