Gruber Beata M, Anuszewska Elzbieta L, Roman Iza, Goździk Aneta, Priebe Waldemar, Fokt Izabela
National Institute of Public Health, Department of Biochemistry and Biopharmaceuticals, 30/34 Chełmska Str., 00-725 Warsaw.
Acta Pol Pharm. 2006 Jan-Feb;63(1):15-8.
Topoisomerase II is ATP dependent enzyme that catalyzes DNA strand passage, the pivotal process in replication, transcription, recombination etc. As part of this breakage and religation process the intermediate generated is a cleavable complex between DNA and topoisomerase II. This complex is the target for topoisomerase II inhibitors like epipodophyllotoxins, actinomycin D or anthracyclines. Stabilization of cleavable complexes by the topoisomerase II inhibitors leading to DNA lesions and next to apoptosis is the most common mechanism of drug resistance reflected in reduced formation of the complexes due to decreased amounts and/or activity of topoisomerase II. The aim of this study was to characterize human melanoma and human cervix carcinoma cells differing in sensitivity to doxorubicin and anthracycline analogs, annamycin and WP903 for topoisomerase IIalpha protein and gene expression with use of Western blot and RT- PCR. As shown, no significant differences in topoisomerase IIalpha protein level were noted between the cell lines tested. These results were confirmed at the gene expression level. The current study points to the fact that topoisomerase IIalpha protein or gene expression are not the reliable marker of cell sensitivity to anthracyclines but these observations do not exclude the potential mutations in topoisomerase IIalpha gene or some postranslational changes in that protein which requires further studies.
拓扑异构酶II是一种依赖ATP的酶，它催化DNA链的通过，这是复制、转录、重组等过程中的关键步骤。作为这种断裂和重新连接过程的一部分，产生的中间体是DNA与拓扑异构酶II之间的可裂解复合物。这种复合物是拓扑异构酶II抑制剂（如表鬼臼毒素、放线菌素D或蒽环类药物）的作用靶点。拓扑异构酶II抑制剂使可裂解复合物稳定，导致DNA损伤，进而引发细胞凋亡，这是耐药性的最常见机制，表现为由于拓扑异构酶II的量和/或活性降低，复合物的形成减少。本研究的目的是利用蛋白质免疫印迹法和逆转录聚合酶链反应，对人黑色素瘤细胞和人子宫颈癌细胞进行表征，这些细胞对阿霉素、蒽环类类似物安那霉素和WP903的拓扑异构酶IIα蛋白和基因表达的敏感性不同。结果显示，在所测试的细胞系之间，拓扑异构酶IIα蛋白水平没有显著差异。这些结果在基因表达水平上得到了证实。当前的研究指出，拓扑异构酶IIα蛋白或基因表达并非细胞对蒽环类药物敏感性的可靠标志物，但这些观察结果并不排除拓扑异构酶IIα基因存在潜在突变或该蛋白存在某些翻译后变化的可能性，这需要进一步研究。
