Burger H, Nooter K, Boersma A W, Kortland C J, Stoter G
Department of Medical Oncology, University Hospital Rotterdam and Rotterdam Cancer Institute (Daniel den Hoed Kliniek), The Netherlands.
Br J Cancer. 1998 May;77(10):1562-7. doi: 10.1038/bjc.1998.257.
We examined the sensitivity for cisplatin-induced apoptosis in a panel of four testicular germ cell tumour (TGCT) cell lines and monitored the cellular expression of the apoptosis-related proteins p53, Bcl-2 and Bax. Three of four TGCT cell lines (NT2, NCCIT and S2) were hypersensitive for cisplatin-induced apoptosis, while the TGCT cell line 2102 EP appeared to be resistant for cisplatin-induced apoptosis, even at relatively high drug concentrations (12.5 microM). For all four cell lines, the induction of apoptosis by cisplatin correlated with drug sensitivity in the MTT assay. The differences in chemosensitivity and induction of apoptosis could not be attributed to differences in cellular platinum accumulation, DNA platination or platinum-DNA adduct removal. We next analysed the relationship between p53 status and cisplatin-induced up-regulation of p53, and the susceptibility to cisplatin-induced apoptosis. Wild-type p53 containing NT2 and 2102 EP cells showed p53 up-regulation upon drug treatment, and NCCIT (mutant p53) and S2 (no p53 protein) cells did not. Consistently, the increase in wild-type p53 protein in NT2 and 2102 EP cells led to an increase in mRNA level of the p53 downstream gene p21/WAF/CIP, whereas mutant p53-containing NCCIT cells and p53-non-expressing S2 cells could not transactivate this p53-responsive gene. As NT2, NCCIT and S2 were readily triggered into apoptosis, while 2102 EP cells failed to undergo cisplatin-induced apoptosis, our data suggest that the presence of wild-type and/or transactivation-competent p53 might not be an absolute prerequisite for efficient induction of apoptosis in TGCT cell lines. Also endogenous levels of Bcl-2 and Bax expression did not correlate with cisplatin-induced apoptosis. In addition, the endogenous Bcl-2 and Bax expression was not affected by cisplatin treatment. The present study suggests that, at least in our panel of TGCT cell lines, hypersensitivity for cisplatin-induced apoptosis might not be necessarily correlated with the presence of wild-type p53 and is probably not associated with Bcl-2 and Bax expression.
我们检测了四种睾丸生殖细胞肿瘤（TGCT）细胞系对顺铂诱导凋亡的敏感性，并监测了凋亡相关蛋白p53、Bcl-2和Bax的细胞表达。四种TGCT细胞系中的三种（NT2、NCCIT和S2）对顺铂诱导的凋亡高度敏感，而TGCT细胞系2102 EP即使在相对较高的药物浓度（12.5 microM）下，似乎也对顺铂诱导的凋亡具有抗性。对于所有四种细胞系，顺铂诱导的凋亡与MTT试验中的药物敏感性相关。化学敏感性和凋亡诱导的差异不能归因于细胞铂积累、DNA铂化或铂-DNA加合物清除的差异。接下来，我们分析了p53状态与顺铂诱导的p53上调之间的关系，以及对顺铂诱导凋亡的敏感性。含有野生型p53的NT2和2102 EP细胞在药物处理后显示p53上调，而NCCIT（突变型p53）和S2（无p53蛋白）细胞则没有。一致地，NT2和2102 EP细胞中野生型p53蛋白的增加导致p53下游基因p21/WAF/CIP的mRNA水平升高，而含有突变型p53的NCCIT细胞和不表达p53的S2细胞不能激活这个p53反应基因。由于NT2、NCCIT和S2容易被诱导凋亡，而2102 EP细胞未能发生顺铂诱导的凋亡，我们的数据表明，野生型和/或具有反式激活能力的p53的存在可能不是TGCT细胞系中有效诱导凋亡的绝对先决条件。此外，Bcl-2和Bax的内源性表达水平与顺铂诱导的凋亡无关。此外，顺铂处理不影响Bcl-2和Bax的内源性表达。本研究表明，至少在我们的TGCT细胞系中，对顺铂诱导凋亡的高度敏感性不一定与野生型p53的存在相关，可能也与Bcl-2和Bax的表达无关。
