Homologous recombination is the principal pathway for the repair of DNA damage induced by tirapazamine in mammalian cells
Homologous recombination is the principal pathway for the repair of DNA damage induced by tirapazamine in mammalian cells
复制标题
DOI：
10.1158/0008-5472.can-06-4497
复制
发表时间：
2008-01-01
期刊：
影响因子：
11.2
通讯作者：
Brown, J. Martin
中科院分区：
文献类型：
--
作者：
Evans, James W.;Chernikova, Sophia B.;Brown, J. Martin
替拉帕嗪（3-氨基-1,2,4-苯并三嗪-1,4-二氧化）是一种很有前途的低氧选择性细胞毒素，在晚期临床试验中与放疗和顺铂联合使用显示出显著的活性。目前的研究旨在提高我们对替拉帕嗪诱导的病变及其修复途径的理解。我们发现，同源重组在替拉帕嗪诱导的损伤修复中起着关键作用，因为同源重组蛋白XRCC2、XRCC3、Rad51D、BRCA1或BRCA2缺陷的细胞对替拉帕嗪特别敏感。与同源重组修复的参与一致，我们观察到在替拉帕胺治疗后广泛的姐妹染色单体交换。我们还表明，非同源末端连接途径，主要处理直接双链断裂（DSB），不参与替拉帕嗪诱导的DSB的修复。此外，我们发现替拉帕嗪优先杀死XPF/ERCCI缺陷（但不包括其他核苷酸切除修复因子）和碱基切除修复缺陷的突变体。替拉帕嗪还能诱导dna -蛋白质交联，包括稳定的dna -拓扑异构酶I可切割复合物。我们进一步发现，DNA dsb的指示物γ - H2AX在细胞周期的S期优先被诱导。这些观察结果使我们建立了一个替拉帕嗪损伤的整体模型，其中DNA单链断裂、碱基损伤和DNA-蛋白质交联（包括拓扑异构酶I和II可切割复合物）产生复制叉的停滞和崩溃，其分辨率导致DSB中间体，需要同源重组和XPF/ERCC1进行修复。
Tirapazamine (3-amino-1,2,4-benzotriazine-1,4-dioxide) is a promising hypoxia-selective cytotoxin that has shown significant activity in advanced clinical trials in combination with radiotherapy and cisplatin. The current study aimed to advance our understanding of tirapazamine-induced lesions and the pathways involved in their repair. We show that homologous recombination plays a critical role in repair of tirapazamine-induced damage because cells defective in homologous recombination proteins XRCC2, XRCC3, Rad51D, BRCA1, or BRCA2 are particularly sensitive to tirapazamine. Consistent with the involvement of homologous recombination repair, we observed extensive sister chromatid exchanges after treatment with tirapazamine. We also show that the nonhomologous end-joining pathway, which predominantly deals with frank double-strand breaks (DSB), is not involved in the repair of tirapazamine-induced DSBs. In addition, we show that tirapazamine preferentially kills mutants both with defects in XPF/ERCCI (but not in other nucleotide excision repair factors) and with defects in base excision repair. Tirapazamine also induces DNA-protein cross-links, which include stable DNA-topoisomerase I cleavable complexes. We further show that gamma H2AX an indicator of DNA DSBs, is induced preferentially in cells in the S phase of the cell cycle. These observations lead us to an overall model of tirapazamine damage in which DNA single-strand breaks, base damage, and DNA-protein cross-links (including topoisomerase I and II cleavable complexes) produce stalling and collapse of replication forks, the resolution of which results in DSB intermediates, requiring homologous recombination and XPF/ERCC1 for their repair.