Replication-Dependent and Transcription-Dependent Mechanisms of DNA Double-Strand Break Induction by the Topoisomerase 2-Targeting Drug Etoposide
Replication-Dependent and Transcription-Dependent Mechanisms of DNA Double-Strand Break Induction by the Topoisomerase 2-Targeting Drug Etoposide
复制标题
DOI：
10.1371/journal.pone.0079202
复制
发表时间：
2013-11-07
期刊：
影响因子：
3.7
通讯作者：
Yan, Hong
中科院分区：
文献类型：
--
作者：
Tammaro, Margaret;Barr, Peri;Yan, Hong
依托泊苷是一种DNA拓扑异构酶2靶向药物，广泛用于治疗癌症。依托泊苷的细胞毒性与DNA双链断裂（DSBs）的产生有关，但其在细胞中诱导DSBs的机制尚不清楚。催化上，依托泊苷在切割DNA的两条链后抑制Top2的再连接反应，将其捕获在一个可切割的复合体中，该复合体由两个Top2亚基共价连接到DNA的5'端（Top2cc）。Top2cc不能被细胞直接识别为真正的DSB，因为这两个亚基相互作用很强，将DNA的两端固定在一起。在这项研究中，我们研究了将Top2ccs转化为真正的dsb的细胞机制。我们的数据表明有两种机制，一种依赖于主动复制，另一种依赖于蛋白质水解和转录。各机制的相对贡献受依托泊苷浓度的影响。我们还发现，Top2 α是介导复制依赖机制的主要亚型，Top2 α和Top2 α都介导转录依赖机制。这些发现对提高依托泊苷在肿瘤治疗中的疗效具有潜在的重要意义。
Etoposide is a DNA topoisomerase 2-targeting drug widely used for the treatment of cancer. The cytoxicity of etoposide correlates with the generation of DNA double-strand breaks (DSBs), but the mechanism of how it induces DSBs in cells is still poorly understood. Catalytically, etoposide inhibits the re-ligation reaction of Top2 after it nicks the two strands of DNA, trapping it in a cleavable complex consisting of two Top2 subunits covalently linked to the 5' ends of DNA (Top2cc). Top2cc is not directly recognized as a true DSB by cells because the two subunits interact strongly with each other to hold the two ends of DNA together. In this study we have investigated the cellular mechanisms that convert Top2ccs into true DSBs. Our data suggest that there are two mechanisms, one dependent on active replication and the other dependent on proteolysis and transcription. The relative contribution of each mechanism is affected by the concentration of etoposide. We also find that Top2 alpha is the major isoform mediating the replication-dependent mechanism and both Top2 alpha and Top2 mediate the transcription-dependent mechanism. These findings are potentially of great significance to the improvement of etoposide's efficacy in cancer therapy.