以DNA拓扑异构酶Ⅱ为靶点的一种抗癌药筛选的新方法

借鉴文献方法,我们以小鼠L_(1210)白血病细胞为村料,提取DNA拓扑异构酶Ⅱ,鉴别了其生物学特性,并观察了十多种已知及未知的抗癌药物对其活性的影响,初步建立了以DNA拓扑异构酶Ⅱ为靶点的新抗癌药筛选方法。实验表明DNA拓扑异构酶Ⅱ对DNA链切割反应是可逆的,并且高浓度的氯化钠对其活性有抑制作用。许多药物能促进拓扑酶Ⅱ引起的DNA链断裂如ADM、DNR、Vp16及ACM—B等,而另一些药物如萜类化合物BC_1、BC_4等则能抑制链断裂反应。

DETERMINATION OF DNA TOPOISOM ERASE II FROM MOUSE LEUKEMIA L1210 CELLS A TARGET FOR SCREENING ANTITUMOR AGENTS

DNA topoisomerases play very important roles in DNA breakage, reunion replication, and other genetic processes. Recently it has been found that DNA topoi-somerases I and II are fruitful targets for both antimicrobial and oncologic drug development. In the present work a new method for screening antitumor agents by using DNA top-oisomerase II as a target has been established according to the phenomena that the enzyme activity can be affectd by some types of antitumor agent.Based on the method reported by Sullivan et al. with some modification, the DNA top-oisomerase II was extracted from mouse leukemia L1210 cells. The experiments have shown that this enzyme can catalyze pBR 322 DNA breaking and relaxing which are revesible and can be inhibited by high concentration of sodium chloride. Experiments also showed that p-BR DNA cleavage induced by the enzyme can be stimulated by some antitumor drugs. The cleavage reaction activity increased fivefold in the presence of 1 ug/ml of ADM or DNR. Vp-16 and ACM-B can also stimulated the reaction in the higher concentration. The results, however, also indicated that the cleavage reaction resulted from topoisomerase II can be inhibited by other antitumor agents, such as herb ectracts, BC series.