Analysis of Bisdioxopiperazine Dexrazoxane Binding to Human DNA Topoisomerase II : Decreased Binding as a Mechanism of Drug Resistan
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- 作者：Axelle Renodon-Corniè ; re ; Lars H. Jensen ; John L. Nitiss ; Peter B. Jensen ; and Maxwell Sehested
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：August 19, 2003
- 年：2003
- 卷：42
- 期：32
- 页码：9749 - 9754
- 全文大小：75K
- 年卷期：v.42,no.32(August 19, 2003)
- ISSN：1520-4995
文摘
Topoisomerase II is an ATP-operated clamp that effects topological changes by capturing adouble stranded DNA segment and transporting it through another DNA molecule. Despite the extensiveuse of topoisomerase II-targeted drugs in cancer chemotherapy and the impact of drug resistance on theefficacy of treatment, much remains unknown concerning the interactions between these agents andtopoisomerase II. To identify the interaction of the bisdioxopiperazine dexrazoxane (ICRF-187) withtopoisomerase II, we developed a rapid gel-filtration assay and characterized the binding of (3H)-dexrazoxane to human topoisomerase II 
. Dexrazoxane binds to human topoisomerase II in the presenceof DNA and ATP with an apparent Kd of 23 
M and a stoichiometry of 1 drug molecule per enzymedimer. Various N-terminal single amino acid substitutions in human topoisomerase II that were previouslyshown to confer specific bisdioxopiperazine resistance either totally abolished drug binding or resulted inless efficient binding. The effect of the various mutations on drug binding correlated well with theireffect on drug resistance in vivo and in vitro. Interestingly, an altered active site tyrosine mutant of humantopoisomerase II , which is incapable of carrying out DNA strand passage, was unable to bind dexrazoxane,which agrees with the drug's proposed mechanism of action late in the topoisomerase II catalytic cycle.The direct correlation between the level of drug binding and dexrazoxane resistance is consistent with adecreased drug binding mechanism of action for these dexrazoxane resistance conferring mutations.
. Dexrazoxane binds to human topoisomerase II in the presenceof DNA and ATP with an apparent Kd of 23 M and a stoichiometry of 1 drug molecule per enzymedimer. Various N-terminal single amino acid substitutions in human topoisomerase II that were previouslyshown to confer specific bisdioxopiperazine resistance either totally abolished drug binding or resulted inless efficient binding. The effect of the various mutations on drug binding correlated well with theireffect on drug resistance in vivo and in vitro. Interestingly, an altered active site tyrosine mutant of humantopoisomerase II , which is incapable of carrying out DNA strand passage, was unable to bind dexrazoxane,which agrees with the drug's proposed mechanism of action late in the topoisomerase II catalytic cycle.The direct correlation between the level of drug binding and dexrazoxane resistance is consistent with adecreased drug binding mechanism of action for these dexrazoxane resistance conferring mutations.