Ling Y H, Yang Y, Tornos C, Singh B, Perez-Soler R
Department of Thoracic/Head and Neck Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Cancer Res. 1998 Aug 15;58(16):3633-40.
The c-Mos gene product is a component of the cytostatic factor and, as such, stabilizes the maturation-promoting factor causing cell-cycle blockade at metaphase II in unfertilized eggs. The potential role of c-Mos in regulating cell-cycle progression and cell death in somatic cells remains unknown. We studied whether paclitaxel-induced M-phase arrest and apoptosis are associated with c-Mos gene expression and activation in SKOV3 ovarian carcinoma cells. The first cellular effect observed with continuous exposure to 50 ng/ml paclitaxel (ID50) was mitotic arrest with an increase in the accumulation of cyclin B1 and stimulation of cdc2/cyclin B1 kinase in a time-dependent manner during a 36-h incubation. DNA fragmentation determined by agarose gel electrophoresis and quantitation of [3H]thymidine-prelabeled genomic DNA was a later event, first detected at 24 h and peaking at 48 h (later time points were not studied). Induction of the c-Mos gene expression and activation were determined by Western blot analysis, immunoprecipitation using a polyclonal anti-mos antibody, reverse transcription-PCR assay, and 32P-ATP incorporation into c-Mos protein or the substrate of glutathione S-transferase mitogen-activated protein kinase kinase, respectively. Both induction and activation were clearly detected after 24 h of exposure to paclitaxel concentrations of >50 ng/ml, coinciding with drug-induced apoptosis. Mitogen-activated protein kinase activation preceded c-Mos gene induction. Paclitaxel-induced c-Mos gene expression was completely abrogated by cycloheximide and actinomycin D. Mos gene expression was also induced in SKOV3 cells that were treated with vinblastine but not in those that were treated with camptothecin, etoposide, or cisplatin. We concluded that tubulin-disturbing agents induce c-Mos gene expression and activation in SKOV3 ovarian carcinoma cells and that such an effect occurs after mitotic blockade and coincides with drug-induced apoptosis.
c-Mos基因产物是细胞静止因子的一个组成部分，因此，它能稳定促进成熟因子，导致未受精卵在减数分裂中期II出现细胞周期阻滞。c-Mos在调节体细胞的细胞周期进程和细胞死亡中的潜在作用仍然未知。我们研究了紫杉醇诱导的M期阻滞和细胞凋亡是否与SKOV3卵巢癌细胞中的c-Mos基因表达及激活有关。连续暴露于50 ng/ml紫杉醇（半数抑制浓度）后观察到的第一个细胞效应是有丝分裂阻滞，在36小时的孵育过程中，细胞周期蛋白B1的积累增加，并且细胞周期蛋白依赖性激酶2/细胞周期蛋白B1激酶以时间依赖性方式受到刺激。通过琼脂糖凝胶电泳测定的DNA片段化以及对[3H]胸腺嘧啶预标记基因组DNA的定量分析是较晚出现的事件，最早在24小时检测到，并在48小时达到峰值（未研究更晚的时间点）。通过蛋白质免疫印迹分析、使用多克隆抗Mos抗体的免疫沉淀、逆转录聚合酶链反应测定以及分别将32P-ATP掺入c-Mos蛋白或谷胱甘肽S-转移酶丝裂原活化蛋白激酶激酶的底物中来确定c-Mos基因的表达诱导和激活情况。在暴露于>50 ng/ml的紫杉醇24小时后，明显检测到诱导和激活，这与药物诱导的细胞凋亡同时发生。丝裂原活化蛋白激酶的激活先于c-Mos基因的诱导。紫杉醇诱导的c-Mos基因表达被放线菌酮和放线菌素D完全消除。用长春碱处理的SKOV3细胞中也诱导了Mos基因表达，但用喜树碱、依托泊苷或顺铂处理的细胞中未诱导。我们得出结论，微管干扰剂在SKOV3卵巢癌细胞中诱导c-Mos基因表达和激活，并且这种效应发生在有丝分裂阻滞之后，与药物诱导的细胞凋亡同时发生。
