ALTERED CATALYTIC ACTIVITY OF AND DNA CLEAVAGE BY DNA TOPOISOMERASE II FROM HUMAN-LEUKEMIC CELLS SELECTED FOR RESISTANCE TO VM-26
ALTERED CATALYTIC ACTIVITY OF AND DNA CLEAVAGE BY DNA TOPOISOMERASE II FROM HUMAN-LEUKEMIC CELLS SELECTED FOR RESISTANCE TO VM-26
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DOI：
10.1021/bi00424a026
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发表时间：
1988-11-29
期刊：
影响因子：
2.9
通讯作者：
BECK, WT
中科院分区：
文献类型：
--
作者：
DANKS, MK;SCHMIDT, CA;BECK, WT
几类天然产物抗癌药物在仅与其中一种药物接触后，同时对其细胞毒作用产生耐药性，称为多重耐药(MDR)。至少有两种不同的MDR机制被推测：与P-糖蛋白相关的机制和被认为是由于DNA拓扑异构酶II活性改变(at-MDR)所致的机制。我们描述了人类白血病CCRF-CEM细胞的两个亚系的研究。50倍抗性(CEM/Vm-1)和.apprxeq.对已知干扰DNA拓扑异构酶II活性的药物VM-26具有140倍的耐药性(CEM/VM-1-5)。这些株系对其他已知影响拓扑异构酶II的药物具有交叉抗药性，但对长春花碱没有交叉抗药性，长春花碱是有丝分裂纺锤体形成的抑制剂。在两个抗性细胞系和亲本细胞系的1.0M氯化钠核抽提物中，我们发现免疫活性DNA拓扑异构酶II的数量几乎没有差异。然而，抗性亚系细胞核提取物中的拓扑异构酶II在该酶对DNA裂解的催化活性(解结)两个方面都发生了变化。此外，使用CEM/VM-1-5制备时，连锁发生的速度要慢20-30倍。Vm-26对链传递和DNA裂解的影响与每个细胞系的原发耐药程度成反比。我们的数据支持这样的假设，即AT-MDR是由于拓扑异构酶II的改变或调节其活性的因素所致。
The simultaneous development of resistance to the cytotoxic effects of several classes of natural product anticancer drugs, after exposure to only one of these agents, is referred to as multiple drug resistance (MDR). At least two distinct mechanisms for MDR have been postulated: that associated with P-glycoprotein and that thought to be due to an alteration in DNA topoisomerase II activity (at-MDR). We describe studies with two sublines of human leukemic CCRF-CEM cells .apprxeq. 50-fold resistant (CEM/VM-1) and .apprxeq. 140-fold resistant (CEM/VM-1-5) to VM-26, a drug known to interfere with DNA topoisomerase II activity. Each of these lines is cross-resistant to other drugs known to affect topoisomerase II but not cross-resistant to vinblastine, an inhibitor of mitotic spindle formation. We found little difference in the amount of immunoreactive DNA topoisomerase II in 1.0 M NaCl nuclear extracts of the two resistant and parental cell lines. However, topoisomerase II in nuclear extracts of the resistant sublines is altered in both catalytic activity (unknotting) of an DNA cleavage by this enzyme. Also, the rate at which catenation occurs is 20-30-fold slower with the CEM/VM-1-5 preparatons. The effect of VM-26 on both strand passing and DNA cleavage is inversely related to the degree of primary resistance of each cell line. Our data support the hypothesis that at-MDR is due to an alteration in topoisomerase II or in a factor modulating its activity.