Del Bino G, Skierski J S, Darzynkiewicz Z
Cancer Research Institute, New York Medical College, Elmsford 10523.
Exp Cell Res. 1991 Aug;195(2):485-91. doi: 10.1016/0014-4827(91)90400-o.
Exposure of promyelocytic leukemic HL-60 cells to 3-60 nM of the DNA topoisomerase I inhibitor camptothecin (CAM) or to 30-450 nM and 0.12-1.5 microM of DNA topoisomerase II inhibitors teniposide (TN) and 4-(9-acridynylamino)-3-methanesulfon-m-anisidide (m-AMSA), respectively, resulted in two distinct kinetic effects: (1) the cells entered S phase but the rate of DNA replication was reduced in proportion to the inhibitor concentration; (2) the transition from G2 to M was impaired, approximately 1 h after addition of the inhibitor. As a consequence, the cells accumulated in the S (preferentially in early S) and in G2 phases of the cell cycle. Whereas CAM was more efficient in suppressing cell progression through S phase, TN and m-AMSA were more potent G2 blockers. At these low inhibitor concentrations no signs of immediate cytotoxicity or DNA degradation were apparent. However, above 145 nM of CAM, 900 nM of TN, or 2 microM of m-AMSA extensive DNA degradation in nuclei of S phase cells was evident within 6 h of addition of the inhibitor, resulting in the loss of S and G2 + M cells from these cultures. The data indicate that depending on concentration, mechanisms mediating the cytostatic/cytotoxic activity of both DNA topoisomerase I and II inhibitors may be quite different. Suppression of the DNA replication and the G2 to M transition, seen at low inhibitor concentrations, is compatible with the assumption that the inhibitor-induced stabilization of the topoisomerase-DNA cleavable complexes interferes with DNA replication and chromosome condensation/segregation, respectively. Above the threshold concentration for each inhibitor, an endonucleolytic activity is triggered, resulting in rapid DNA degradation in nuclei of S and G2 phase cells. The endonucleolytic effect is not only cell cycle phase-specific but is also modulated by tissue-specific factors because it cannot be observed, e.g., in the lymphocytic leukemic cell lines.
将早幼粒细胞白血病HL-60细胞分别暴露于3-60 nM的DNA拓扑异构酶I抑制剂喜树碱（CAM）、30-450 nM的DNA拓扑异构酶II抑制剂替尼泊苷（TN）和0.12-1.5 microM的4-(9-吖啶基氨基)-3-甲磺酰基间茴香胺（m-AMSA）中，会产生两种不同的动力学效应：（1）细胞进入S期，但DNA复制速率随抑制剂浓度的增加而降低；（2）在添加抑制剂约1小时后，从G2期到M期的转变受到损害。结果，细胞积聚在细胞周期的S期（优先在S期早期）和G2期。虽然CAM在抑制细胞通过S期进展方面更有效，但TN和m-AMSA是更有效的G2期阻滞剂。在这些低抑制剂浓度下，没有明显的即时细胞毒性或DNA降解迹象。然而，在添加抑制剂6小时内，当CAM浓度高于145 nM、TN浓度高于900 nM或m-AMSA浓度高于2 microM时，S期细胞核中会出现广泛的DNA降解，导致这些培养物中S期和G2+M期细胞的丢失。数据表明，根据浓度不同，介导DNA拓扑异构酶I和II抑制剂的细胞生长抑制/细胞毒性活性的机制可能有很大差异。在低抑制剂浓度下观察到的DNA复制抑制和从G2期到M期的转变抑制，符合以下假设：抑制剂诱导的拓扑异构酶-DNA可裂解复合物的稳定分别干扰了DNA复制和染色体浓缩/分离。在每种抑制剂的阈值浓度以上，会触发核酸内切酶活性，导致S期和G2期细胞核中的DNA迅速降解。核酸内切酶效应不仅具有细胞周期阶段特异性，还受组织特异性因素的调节，因为例如在淋巴细胞白血病细胞系中无法观察到这种效应。
