Cassinelli G, Supino R, Perego P, Polizzi D, Lanzi C, Pratesi G, Zunino F
Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1, 20133 Milan, Italy.
Int J Cancer. 2001 Jun 1;92(5):738-47. doi: 10.1002/1097-0215(20010601)92:5<738::aid-ijc1249>3.0.co;2-2.
Loss of p53 function has been linked to increased responsiveness to taxane treatment of ovarian carcinoma in clinical studies. We recently reported that the acquisition of cisplatin resistance in an ovarian carcinoma cell line (IGROV-1) was associated with mutation of p53 and collateral sensitivity to paclitaxel. The increased sensitivity to paclitaxel of the cisplatin-resistant subline appeared to be pharmacologically relevant since it was reflected in an in vivo sensitization to taxanes. To investigate the cellular and molecular basis of this phenomenon, we performed a comparative study of cellular response to taxanes (paclitaxel and the novel analog IDN 5109) in the parental cell line, containing wild-type p53 and its cisplatin-resistant p53 mutant subline (IGROV-1/Pt1). IDN 5109 was included in this study because of its higher potency and efficacy compared with paclitaxel on both tumor systems. The pattern of cellular response of the two ovarian cell lines was different. In IGROV-1 cells, apoptosis was an early event consequent to a transient mitotic arrest. The cell death of IGROV-1/Pt1 cells was a somewhat slow and delayed event, following mitotic arrest and appearance of hyperploid cells. The increased cytotoxic effect of IDN 5109, compared with paclitaxel, was associated with more marked p34(cdc2) dephosphorylation in IGROV-1 cells and higher Bcl-2 phosphorylation in IGROV-1/Pt1 cells after 24 hr of treatment. In each cell line, these biochemical events were not correlated with parallel levels of mitotic cells. Attempts to reintroduce wild-type p53 in IGROV-1/Pt1 were unsuccessful. However, in other p53-deficient cells (osteosarcoma SAOS), taxane treatment was associated with hyperploid progression and the introduction of wild-type p53 resulted in a reduced sensivity. Although our approach does not allow definitive conclusions, these results suggest that loss of p53-dependent post-mitotic checkpoint results in a different time-course of taxane-induced cell death following DNA reduplication. These events, more evident after exposure to the potent analog IDN 5109, support the notion that the enhanced sensitivity of p53 mutant cells is closely related to the different mode of cell death.
临床研究表明，p53功能缺失与卵巢癌对紫杉烷治疗的反应性增加有关。我们最近报道，卵巢癌细胞系（IGROV-1）中顺铂耐药性的获得与p53突变及对紫杉醇的 collateral 敏感性相关。顺铂耐药亚系对紫杉醇敏感性的增加似乎具有药理学相关性，因为这在体内对紫杉烷的致敏作用中有所体现。为了研究这一现象的细胞和分子基础，我们对亲本细胞系（含有野生型p53）及其顺铂耐药p53突变亚系（IGROV-1/Pt1）对紫杉烷（紫杉醇和新型类似物IDN 5109）的细胞反应进行了比较研究。将IDN 5109纳入本研究是因为其在两种肿瘤系统中比紫杉醇具有更高的效力和疗效。两种卵巢细胞系的细胞反应模式不同。在IGROV-1细胞中，凋亡是短暂有丝分裂停滞后的早期事件。IGROV-1/Pt1细胞的死亡是一个较为缓慢和延迟的事件，发生在有丝分裂停滞和超倍体细胞出现之后。与紫杉醇相比，IDN 5109增强的细胞毒性作用与处理24小时后IGROV-1细胞中更显著的p34(cdc2)去磷酸化以及IGROV-1/Pt1细胞中更高的Bcl-2磷酸化相关。在每个细胞系中，这些生化事件与有丝分裂细胞的平行水平无关。在IGROV-1/Pt1中重新引入野生型p53的尝试未成功。然而，在其他p53缺陷细胞（骨肉瘤SAOS）中，紫杉烷处理与超倍体进展相关，而野生型p53的引入导致敏感性降低。尽管我们的方法无法得出明确结论，但这些结果表明，p53依赖的有丝分裂后检查点的缺失导致DNA复制后紫杉烷诱导的细胞死亡具有不同的时间进程。这些事件在暴露于强效类似物IDN 5109后更为明显，支持了p53突变细胞增强的敏感性与不同细胞死亡模式密切相关的观点。
