Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Chem Res Toxicol. 2010 Nov 15;23(11):1833-42. doi: 10.1021/tx1002904. Epub 2010 Oct 12.
cis-Amminedichlorido(cyclohexylamine)platinum(II) (JM118) is an antitumor Pt(II) analogue of cisplatin exhibiting considerably higher activity than cisplatin in human tumor cells. JM118 is also the major metabolite of the first orally administered Pt(IV) drug satraplatin. In an effort to design improved platinum antitumor agents, it is important to elucidate the biochemical factors that affect the cytotoxic properties of existing platinum drugs. Since DNA is considered the major pharmacological target of platinum drugs, the objective in the present work was to understand more fully the DNA binding mode of antitumor JM118. We examined the rate of aquation of the first chloride of bifunctional JM118 and found that it was considerably lower than that of cisplatin; consequently, the rate of the reaction of JM118 with DNA was lower compared to cisplatin. The influence of global modification by JM118 and its major site-specific adducts on DNA conformation by biochemical methods was investigated as well. While examination of the global modification revealed in several cases no substantial differences in the lesions induced by JM118 and cisplatin, DNA bending due to the 1,2-GG intrastrand adduct of JM118 was lower than that of cisplatin. The bending angles afforded by the adducts of JM118 were only slightly affected by the orientation of the cyclohexylamine ligand toward the 3' or 5' direction of the duplex. We also used in vitro assays that make it possible to monitor DNA repair synthesis by cell-free extracts and DNA-protein cross-linking to probe properties of DNA adducts of JM118. These results showed a higher DNA-protein cross-linking efficiency of JM118 and a less efficient removal from DNA of the adducts of JM118 in comparison with cisplatin. Thus, the results of the present work provide additional evidence that DNA binding of JM118 is in several aspects different from that of conventional cisplatin.
顺式-氨二氯环己胺合铂（II）（JM118）是顺铂的抗肿瘤铂（II）类似物，在人类肿瘤细胞中比顺铂具有更高的活性。JM118 也是首个口服铂（IV）药物 satraplatin 的主要代谢物。为了设计出更有效的铂类抗肿瘤药物，阐明影响现有铂类药物细胞毒性的生化因素非常重要。由于 DNA 被认为是铂类药物的主要药理靶点，因此本工作的目的是更全面地了解抗肿瘤 JM118 的 DNA 结合模式。我们检查了双功能 JM118 的第一个氯的水解速率，发现它明显低于顺铂；因此，JM118 与 DNA 的反应速率低于顺铂。我们还研究了 JM118 及其主要的特异性加合物对 DNA 构象的全局修饰的影响，用生化方法进行研究。虽然检查全局修饰发现 JM118 和顺铂诱导的损伤没有实质性差异，但由于 JM118 的 1,2-GG 链内加合物导致的 DNA 弯曲程度低于顺铂。JM118 加合物提供的弯曲角度仅受到环己胺配体朝向双链体 3'或 5'方向的取向的轻微影响。我们还使用体外测定，这些测定可以监测无细胞提取物中的 DNA 修复合成和 DNA-蛋白质交联，以探测 JM118 的 DNA 加合物的性质。这些结果表明 JM118 的 DNA-蛋白质交联效率更高，并且与顺铂相比，JM118 的加合物从 DNA 中去除的效率较低。因此，本工作的结果提供了额外的证据，表明 JM118 的 DNA 结合在几个方面与传统的顺铂不同。
