Chen G, Hutter K, Zeller W
GERMAN CANC RES CTR,INST TOXICOL & CHEMOTHERAPY,W-6900 HEIDELBERG,GERMANY. GERMAN CANC RES CTR,INST RADIOL,W-6900 HEIDELBERG,GERMANY.
Int J Oncol. 1992 Jul;1(2):135-40. doi: 10.3892/ijo.1.2.135.
The proliferation of a rat ovarian tumor cell line (O-342) was completely inhibited by a 2 h exposure to 20 muM cisplatin (DDP) in vitro up to 120 h after its removal, while in its DDP resistant subline (O-342/DDP), the same treatment only caused a transient growth inhibition within the first 24 h post the exposure, followed by the recovery of proliferation at a similar rate as the control cells. DNA interstrand cross links (ISCL) were maximally formed 12 h post DDP treatment in either O-342 or O-342/DDP cells, with a 2.8-fold increase in the sensitive cells at this time (262 vs. 95 rad eq.). After further 12 h incubation, however, 75% of DNA-ISCL was removed in O-342/DDP cells, while only 22% of them were repaired in O-342 cells. DNA single strand breaks (SSB) were produced to a similar extent in both lines but reached a maximum at 12 and 24 h in the resistant and the sensitive cells, respectively. ADP-ribosyl transferase (ADPRT) activity, a DNA repair-associated enzyme, was 2.6-fold higher in O-342/DDP cells compared to the sensitive subline. Following DDP treatment, the activity was stimulated in the sensitive cells with a maximum of about 1.5-fold at 24 h, whereas the inhibitory effect was observed in the resistant cells, although at 12 h it recovered almost to the control level. Flow cytometric analysis showed that there were at least two sub-populations (2n and 4n) in O-342 cells, while only 2n population was observed in O-342/DDP cells. Following DDP exposure, O-342/DDP cells progressed through the cell cycle with only a small and transient accumulation of cells in S-phase at 12 h and 24 h, while in the sensitive cells, it was impossible to distinguish cell-cycle distribution at 12 h due to severe damage, at 24 h most of the cells became arrested in G2-phases, which persisted until the end of the observation (48 h). Our results suggest that both reduced interaction of cellular DNA with DDP and increased DNA repair are contributing factors for development of DDP resistance, which might be directly or indirectly subsequent to alterations of poly (ADP-ribose) metabolism in the resistant cells.
大鼠卵巢肿瘤细胞系（O-342）在体外暴露于20μM顺铂（DDP）2小时后，其增殖在去除药物后的120小时内完全受到抑制。而在其顺铂耐药亚系（O-342/DDP）中，相同处理仅在暴露后的前24小时内引起短暂的生长抑制，随后增殖恢复，速率与对照细胞相似。在O-342或O-342/DDP细胞中，DNA链间交联（ISCL）在DDP处理后12小时达到最大值，此时敏感细胞中的ISCL增加了2.8倍（262对95拉德当量）。然而，在进一步孵育12小时后，O-342/DDP细胞中75%的DNA-ISCL被去除，而在O-342细胞中只有22%的DNA-ISCL得到修复。DNA单链断裂（SSB）在两个细胞系中产生的程度相似，但分别在耐药细胞和敏感细胞的12小时和24小时达到最大值。一种与DNA修复相关的酶——ADP-核糖基转移酶（ADPRT）的活性，在O-342/DDP细胞中比敏感亚系高2.6倍。DDP处理后，敏感细胞中的该活性受到刺激，在24小时时最大增加约1.5倍，而在耐药细胞中观察到抑制作用，尽管在12小时时其几乎恢复到对照水平。流式细胞术分析表明，O-342细胞中至少有两个亚群（2n和4n），而在O-342/DDP细胞中仅观察到2n亚群。DDP暴露后，O-342/DDP细胞在细胞周期中进展，仅在12小时和24小时时在S期有少量短暂的细胞积累，而在敏感细胞中，由于严重损伤，在12小时时无法区分细胞周期分布，在24小时时大多数细胞停滞在G2期，并持续到观察结束（48小时）。我们的结果表明，细胞DNA与DDP相互作用的减少和DNA修复的增加都是顺铂耐药发展的促成因素，这可能直接或间接地继发于耐药细胞中多聚（ADP-核糖）代谢的改变。
