Hasinoff B B, Abram M E, Chee G L, Huebner E, Byard E H, Barnabé N, Ferrans V J, Yu Z X, Yalowich J C
Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada.
J Pharmacol Exp Ther. 2000 Nov;295(2):474-83.
The bisdioxopiperazines, including dexrazoxane (ICRF-187), are catalytic or noncleavable complex-forming inhibitors of DNA topoisomerase II that do not produce DNA strand breaks. In this study we show that dexrazoxane inhibits the division of Chinese hamster ovary (CHO) cells resulting in marked increases in cell size (up to 80 microm in diameter), volume (up to 150-fold greater), and ploidy (as high as 32N). This last result indicates that the dexrazoxane-induced DNA reduplication was restricted to once per cell cycle. Kinetic analysis of the flow cytometry data indicated that the conversion between successively higher ploidy levels was progressively slowed at longer times of exposure to dexrazoxane. Both the protein and DNA content of dexrazoxane-treated CHO cells increased linearly over time in the same proportion. Light and electron microscopic studies of dexrazoxane-treated cells showed ring-like multilobulated nuclei. Immunohistochemical staining of dexrazoxane-treated cells showed that F-actin and acetylated alpha-tubulin were present in large, highly organized networks. Immunohistochemical staining of the dexrazoxane-treated CHO cells also showed that the topoisomerase II alpha colocalized with the DNA of the multilobulated nuclei. Staining of gamma-tubulin revealed that the dexrazoxane-treated cells contained multiple centrosomes, indicating that dexrazoxane prevents cytokinesis but not centrosome reduplication. It is concluded that dexrazoxane inhibits CHO cytokinesis in cells by virtue of its ability to inhibit topoisomerase II.
双二氧哌嗪类化合物，包括右丙亚胺（ICRF - 187），是DNA拓扑异构酶II的催化性或不可裂解的复合物形成抑制剂，不会导致DNA链断裂。在本研究中，我们表明右丙亚胺抑制中国仓鼠卵巢（CHO）细胞的分裂，导致细胞大小显著增加（直径可达80微米）、体积（高达150倍）和倍性（高达32N）。最后这一结果表明，右丙亚胺诱导的DNA复制在每个细胞周期中仅发生一次。流式细胞术数据的动力学分析表明，在较长时间暴露于右丙亚胺的情况下，连续更高倍性水平之间的转换逐渐减慢。右丙亚胺处理的CHO细胞的蛋白质和DNA含量随时间呈线性增加，比例相同。对右丙亚胺处理的细胞进行光镜和电镜研究显示有环状多叶核。对右丙亚胺处理的细胞进行免疫组织化学染色显示，F - 肌动蛋白和乙酰化α - 微管蛋白存在于大型、高度有序的网络中。对右丙亚胺处理的CHO细胞进行免疫组织化学染色还显示，拓扑异构酶IIα与多叶核的DNA共定位。γ - 微管蛋白染色显示，右丙亚胺处理的细胞含有多个中心体，表明右丙亚胺阻止胞质分裂但不阻止中心体复制。结论是右丙亚胺凭借其抑制拓扑异构酶II的能力抑制CHO细胞的胞质分裂。
