Elsea S H, Westergaard M, Burden D A, Lomenick J P, Osheroff N
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
Biochemistry. 1997 Mar 11;36(10):2919-24. doi: 10.1021/bi962488f.
Topoisomerase II is the cytotoxic target for a number of clinically relevant antineoplastic drugs. Despite the fact that these agents differ significantly in structure, a previous study [Corbett, A. H., Hong, D., & Osheroff, N. (1993) J. Biol. Chem. 268, 14394-14398] indicated that the site of action for etoposide on topoisomerase II overlaps those of other DNA cleavage-enhancing drugs. Therefore, to further define interactions between drugs and the enzyme, the functional interaction domain (i.e., interaction domain defined by drug function) for quinolones on Drosophila topoisomerase II was mapped with respect to several classes of antineoplastic agents. This was accomplished by characterizing the effects of ciprofloxacin (a gyrase-targeted antibacterial quinolone) on the ability of etoposide, amsacrine, genistein, and the antineoplastic quinolone, CP-115,953, to enhance topoisomerase II-mediated DNA cleavage. Although ciprofloxacin interacts with the eukaryotic type II enzyme, it shows little ability to stimulate DNA cleavage. Ciprofloxacin attenuated cleavage enhancement by all of the above drugs. Similar results were obtained using a related quinolone, CP-80,080, as a competitor. In addition, kinetic analysis of DNA cleavage indicated that ciprofloxacin is a competitive inhibitor of CP-115,953 and etoposide. Finally, ciprofloxacin inhibited the cytotoxic actions of CP-115,953 and etoposide in mammalian cells to an extent that paralleled its in vitro attenuation of cleavage. These results strongly suggest that several structurally disparate DNA cleavage-enhancing antineoplastic drugs share an overlapping site of action on topoisomerase II. Based on the results of drug competition and mutagenesis studies, a model for the drug interaction domain on topoisomerase II is described.
拓扑异构酶II是多种临床相关抗肿瘤药物的细胞毒性靶点。尽管这些药物在结构上有显著差异，但先前的一项研究[科比特，A. H.，洪，D.，& 奥舍罗夫，N.（1993年）《生物化学杂志》268卷，14394 - 14398页]表明，依托泊苷在拓扑异构酶II上的作用位点与其他增强DNA切割的药物的作用位点重叠。因此，为了进一步确定药物与该酶之间的相互作用，针对几类抗肿瘤药物，绘制了喹诺酮类药物在果蝇拓扑异构酶II上的功能相互作用域（即由药物功能定义的相互作用域）。这是通过表征环丙沙星（一种靶向回旋酶的抗菌喹诺酮）对依托泊苷、安吖啶、染料木黄酮和抗肿瘤喹诺酮CP - 115,953增强拓扑异构酶II介导的DNA切割能力的影响来实现的。尽管环丙沙星与真核II型酶相互作用，但其刺激DNA切割的能力较弱。环丙沙星减弱了上述所有药物对切割的增强作用。使用相关喹诺酮CP - 80,080作为竞争剂也获得了类似结果。此外，DNA切割的动力学分析表明，环丙沙星是CP - 115,953和依托泊苷的竞争性抑制剂。最后，环丙沙星在哺乳动物细胞中抑制了CP - 115,953和依托泊苷的细胞毒性作用，其程度与它在体外对切割的减弱程度相当。这些结果强烈表明，几种结构不同的增强DNA切割的抗肿瘤药物在拓扑异构酶II上有重叠的作用位点。基于药物竞争和诱变研究的结果，描述了拓扑异构酶II上药物相互作用域的模型。
