Mechanistic studies of the modulation of cleavage activity of topoisomerase I by DNA adducts of mono- and bi-functional PtII complexes
Mechanistic studies of the modulation of cleavage activity of topoisomerase I by DNA adducts of mono- and bi-functional PtII complexes
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DOI：
10.1093/nar/gkp580
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发表时间：
2009-09-01
影响因子：
14.9
通讯作者：
Brabec, Viktor
中科院分区：
文献类型：
--
作者：
Malina, Jaroslav;Vrana, Oldrich;Brabec, Viktor
使用电泳和复制映射，我们表明，存在的DNA加合物的双功能抗肿瘤顺铂或单齿[PtCl（二烯）]Cl（二烯=二亚乙基三胺）在基板DNA抑制真核拓扑异构酶1（top1）的行动，顺铂的加合物更有效。在铂化DNA样品中喜树碱的存在显著增强Pt-DNA加合物对top1活性的影响。有趣的是，在喜树碱的存在下，Pt-DNA加合物对top1的催化活性的影响根据序列上下文而不同。在切割位点下游的易切割链上的短核苷酸序列的多重置换阻碍了top1的切割。另一方面，DNA切割top1在一些切割位点，没有铂在其附近显着增强作为一个结果的全球铂的DNA。我们认为，这种增强的DNA切割的top1可能包括在其无法结合到其他切割位点铂在其附近，因此，更多的分子的top1可能成为可用于切割的网站，top1通常切割和铂不干扰。
Using electrophoresis and replication mapping, we show that the presence of DNA adducts of bifunctional antitumor cisplatin or monodentate [PtCl(dien)]Cl (dien = diethylenetriamine) in the substrate DNA inhibits eukaryotic topoisomerase 1 (top1) action, the adducts of cisplatin being more effective. The presence of camptothecin in the samples of platinated DNA markedly enhances effects of Pt-DNA adducts on top1 activity. Interestingly, the effects of Pt-DNA adducts on the catalytic activity of top1 in the presence of camptothecin differ depending on the sequence context. A multiple metallation of the short nucleotide sequences on the scissile strand, immediately downstream of the cleavage site impedes the cleavage by top1. On the other hand, DNA cleavage by top1 at some cleavage sites which were not platinated in their close proximity is notably enhanced as a consequence of global platination of DNA. We suggest that this enhancement of DNA cleavage by top1 may consist in its inability to bind to other cleavage sites platinated in their close neighborhood; thus, more molecules of top1 may become available for cleavage at the sites where top1 normally cleaves and where platination does not interfere.