Jobson Andrew G, Willmore Elaine, Tilby Michael J, Mistry Prakash, Charlton Peter, Austin Caroline A
Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle Upon Tyne, NE2 4HH, UK.
Cancer Chemother Pharmacol. 2009 Apr;63(5):889-901. doi: 10.1007/s00280-008-0812-9. Epub 2008 Aug 5.
Previous in vitro cleavage data showed that XR11576 and XR5944 stabilised topoisomerase I and topoisomerase II complexes on DNA in a dose-dependent fashion. However, some studies indicated a possible topoisomerase-independent mechanism of action for these drugs.
Three methods, the TARDIS assay, immunoband depletion and the K(+)/SDS assay have been used to assess topoisomerase complex formation induced by XR11576 or XR5944 in human leukaemic K562 cells.
TARDIS and immunoband depletion assays demonstrated that XR11576 and XR5944 induced complex formation for both topoisomerase I and topoisomerase II (alpha and beta) in a dose- and time-dependent manner, following exposure times of 24 and 48 h at concentrations of 1 or 10 microM. The K(+)/SDS assay showed the formation of protein/DNA complexes after a 1 h exposure to 1 or 10 muM XR11576.
Our data confirm that XR11576 or XR5944 can form topoisomerase complexes, after long periods of exposure.
先前的体外切割数据表明，XR11576和XR5944能以剂量依赖的方式稳定拓扑异构酶I和拓扑异构酶II与DNA的复合物。然而，一些研究表明这些药物可能存在不依赖拓扑异构酶的作用机制。
采用三种方法，即TARDIS分析、免疫条带消耗分析和K(+)/SDS分析，来评估XR11576或XR5944在人白血病K562细胞中诱导的拓扑异构酶复合物形成情况。
TARDIS分析和免疫条带消耗分析表明，在浓度为1或10微摩尔、暴露时间为24和48小时后，XR11576和XR5944以剂量和时间依赖的方式诱导拓扑异构酶I和拓扑异构酶II（α和β）形成复合物。K(+)/SDS分析显示，在暴露于1或10微摩尔XR11576 1小时后形成了蛋白质/DNA复合物。
我们的数据证实，长时间暴露后，XR11576或XR5944可形成拓扑异构酶复合物。
