Defects in interstrand cross-link uncoupling do not account for the extreme sensitivity of ERCC1 and XPF cells to cisplatin
Defects in interstrand cross-link uncoupling do not account for the extreme sensitivity of ERCC1 and XPF cells to cisplatin
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DOI：
10.1093/nar/gkf479
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发表时间：
2002-09-01
影响因子：
14.9
通讯作者：
Hartley, JA
中科院分区：
文献类型：
--
作者：
De Silva, IU;McHugh, PJ;Hartley, JA
抗癌药物顺铂与DNA反应，形成关键的细胞毒性损伤的链间和链内交联物。与携带核苷酸切除修复装置(XPB、XPD、XPG和CSB)其他组件突变的细胞不同，ERCC1-XPF结构特异性核酸酶缺陷的细胞对顺铂高度敏感。为了确定XPF和ERCC1细胞对顺铂的极端敏感性是否源于链内或链间交联修复中的特定缺陷，我们测量了一系列核苷酸切除修复中国仓鼠突变细胞系中这两种损伤的消除情况，包括XPF和ERCC1缺陷细胞。与亲本、修复熟练的细胞系相比，所有测试的突变体在消除这两类加合物方面都存在缺陷，尽管它们的敏感度增加的程度非常不同。因此，在链间交联处的初始切开或去除链内加合物与细胞敏感性之间没有明确的关系。这些结果表明，ERCC1和XPF细胞对顺铂的高敏感性可能是由于除切除修复外的缺陷所致。与其他常规DNA交联剂相比，我们发现顺铂加合物的修复不涉及DNA双链断裂的形成。令人惊讶的是，XRCC2和XRCC3细胞在顺铂链间交联修复的解偶联步骤中存在缺陷，这表明同源重组可能在切除这种类型的交联链之前启动。
The anticancer drug cisplatin reacts with DNA leading to the formation of interstrand and intrastrand cross-links that are the critical cytotoxic lesions. In contrast to cells bearing mutations in other components of the nucleotide excision repair apparatus (XPB, XPD, XPG and CSB), cells defective for the ERCC1-XPF structure-specific nuclease are highly sensitive to cisplatin. To determine if the extreme sensitivity of XPF and ERCC1 cells to cisplatin results from specific defects in the repair of either intrastrand or interstrand cross-links we measured the elimination of both lesions in a range of nucleotide excision repair Chinese hamster mutant cell lines, including XPF- and ERCC1-defective cells. Compared to the parental, repair-proficient cell line all the mutants tested were defective in the elimination of both classes of adduct despite their very different levels of increased sensitivity. Consequently, there is no clear relationship between initial incisions at interstrand cross-links or removal of intrastrand adducts and cellular sensitivity. These results demonstrate that the high cisplatin sensitivity of ERCC1 and XPF cells likely results from a defect other than in excision repair. In contrast to other conventional DNA cross-linking agents, we found that the repair of cisplatin adducts does not involve the formation of DNA double-strand breaks. Surprisingly, XRCC2 and XRCC3 cells are defective in the uncoupling step of cisplatin interstrand cross-link repair, suggesting that homologous recombination might be initiated prior to excision of this type of cross-link.