目的 研究白杨素联合喜树碱对鼻咽癌细胞CNE2凋亡的影响,并对其分子机制做初步探讨。方法 白杨素以不同浓度(10、20、40 μmol/L)单独/联合喜树碱(1 μg/mL)处理CNE2细胞后,于普通及荧光倒置显微镜下观察细胞形态变化,获得细胞死亡的定性资料;MTT法分析细胞活性,获得细胞死亡的定量资料;并以Western blotting方法检测凋亡标志蛋白caspase-3和PARP的变化情况及凋亡抑制蛋白Bcl-xL随时间的变化规律。结果 形态学观察发现,与对照组比较,白杨素联合喜树碱处理CNE2细胞后,细胞出现明显的死亡量增加,而单独白杨素、喜树碱和未处理的对照组则未观察到细胞的明显减少;MTT法分析的定量资料也支持这一结果,联合处理组细胞存活率随着白杨素剂量增加而下降,与未处理的对照组比较均有统计学意义(P<0.05),而且与单独白杨素及单独喜树碱组比较均有统计学意义(P<0.05);Hochest 33342荧光染色在联合处理组可观察到明显的核固缩细胞增加;Western blotting检测到凋亡标志蛋白caspase-3和PARP原蛋白减少、相应的活化裂解片段出现;全caspase酶抑制剂z-VAD-fmk可有效抑制联合处理引起的CNE2细胞凋亡,阻止凋亡标志蛋白caspase-3和PARP的活化降解;喜树碱引起的凋亡抑制蛋白Bcl-xL表达量增加,随联合处理时间延长而明显下调。结论 白杨素联合喜树碱具有促进CNE2细胞凋亡的能力,凋亡抑制蛋白Bcl-xL表达下调是其重要的分子机制。

objective To research whether the combination of chrysin and camptothecin can promote the apoptosis of human nasopharyngeal carcinoma cell line CNE2 and to explore the molecular mechanism of the combinative effect. Methods CNE2 cells were pretreated with designed dose of chrysin (10, 20, and 40 μmol/L) for 2 h, then treated with camptothecin (1 μg/mL) for 24 h. The morphologic changes were observed under inversed microscope and the cell viability was measured using MTT. The activity of caspase-3 and PARP, which was regarded as the protein marks of apoptosis, was determined by Western blotting. Then the cells were treated with chrysin for different time and the time course of apoptosis inhibitory protein, Bcl-xL was also detected using Western blotting. Results Increases of cell death were observed in the group with combined chrysin and camptothecin, but no obvious cell death could be found in chrysin, camptothecin alone, and control groups; The data of cell viability supported this results; With the enhance of pretreatment dose of chrysin, the cell viability decreased. There were the significant differences between the combined groups and the control one (P < 0.05), and between the combined groups and both the chrysin and camptothecin groups separately (P < 0.05). Chromatin condensation, which was the indication of apoptosis, could be observed when the cells were stained with Hochest 33342; The proprotein of caspase-3 and PARP degraded and there were the dose-dependent and time-dependent effect. The pan-caspase inhibitor Z-VAD-fmk could inhibit the apoptosis of CNE2 cells which were treated with the combination of chrysin and camptothecin, according to the cell viability and the activation of caspase-3 and PARP; The time-dependent down-regulation in the apoptosis inhibitory protein Bcl-xL could be observed. Conclusion The cotreatment of chrysin and camptothecin could promote the apoptosis of CNE2 and the down-regulation of apoptosis inhibitory protein Bcl-xL played an important role in the combinative effect.

国家自然科学基金资助项目(81202199);广东省科技计划项目资助(2013B021800044,2014A020212437);广州市科技计划项目 (2014J4100090)