Kaspárková J, Brabec V
Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno.
Biochemistry. 1995 Sep 26;34(38):12379-87. doi: 10.1021/bi00038a035.
Recognition and processing by cellular proteins of DNA modified by platinum complexes have been suggested to be relevant to the mechanism of their antitumor activity. Platinum complexes form on DNA various mono- and bifunctional adducts. It has already been described by other authors that intrastrand cross-links formed on DNA by antitumor cis-diamminedichloroplatinum(II) (cisplatin) between neighboring purine residues are recognized by several DNA-binding proteins. In contrast, these proteins do not recognize the intrastrand cross-links formed on DNA by cisplatin or its clinically ineffective trans isomer (transplatin) between nonadjacent base residues. An eventuality heretofore not addressed is that DNA interstrand cross-links (ICLs) of platinum compounds may be recognized by and bound to DNA-binding proteins. DNA probes of 110 base pairs (bp) were constructed containing five equally spaced ICLs of cisplatin or transplatin. These ICLs were formed at specific sites at which these adducts are preferentially formed in natural DNA. Gel electrophoresis mobility shift and competition assays with these probes were used to investigate the specific recognition and binding of the calf thymus HMG1 protein to the DNA ICLs of both platinum isomers. The ICL of antitumor cisplatin was recognized by and bound to the HMG1 protein with a similar affinity as the 1,2-intrastrand d(GpG) cross-link of this drug. The protein binding to the ICL is selective for the DNA modification by cisplatin, but not by chemotherapeutically inactive transplatin.(ABSTRACT TRUNCATED AT 250 WORDS)
细胞蛋白对铂配合物修饰的DNA的识别和处理被认为与其抗肿瘤活性机制有关。铂配合物在DNA上形成各种单功能和双功能加合物。其他作者已经描述过，抗肿瘤顺二氯二氨铂（II）（顺铂）在相邻嘌呤残基之间在DNA上形成的链内交联被几种DNA结合蛋白识别。相比之下，这些蛋白不能识别顺铂或其临床无效的反式异构体（反铂）在非相邻碱基残基之间在DNA上形成的链内交联。一个迄今为止尚未解决的可能性是，铂化合物的DNA链间交联（ICL）可能被DNA结合蛋白识别并与之结合。构建了含有五个等间距顺铂或反铂ICL的110个碱基对（bp）的DNA探针。这些ICL在天然DNA中优先形成这些加合物的特定位点形成。使用这些探针进行凝胶电泳迁移率变动和竞争试验，以研究小牛胸腺HMG1蛋白对两种铂异构体的DNA ICL的特异性识别和结合。抗肿瘤顺铂的ICL被HMG1蛋白识别并结合，其亲和力与该药物的1,2-链内d（GpG）交联相似。蛋白与ICL的结合对顺铂引起的DNA修饰具有选择性，而对化疗无效的反铂则没有选择性。（摘要截短至250字）
