白桦酯醇诱导宫颈癌HeLa细胞凋亡及作用机制的研究

目的:研究白桦酯醇(betulin)体外诱导人宫颈癌HeLa细胞凋亡的作用,并探讨其可能的作用机制.方法:以不同浓度的白桦酯醇处理HeLa细胞,采用MTT法检测白桦酯醇作用24、48和72 h时对细胞生长抑制的情况；倒置相差显微镜下观察对HeLa细胞形态学变化的影响；TUNEL法检测对细胞凋亡的影响;FCM检测细胞的凋亡率；蛋白质印迹法检测对HeLa细胞中caspase-3和多聚ADP-核糖聚合酶poly (ADP-ribose) polymerase,PARP]蛋白表达的影响.结果:不同浓度的白桦酯醇能抑制HeLa细胞的增殖,且呈时间-剂量依赖关系(P＜0.01);倒置相差显微镜下观察结果显示,白桦酯醇处理24 h后,细胞体积缩小,核固缩,细胞的折光性减弱,且随着白桦酯醇浓度的增加上述形态变化增强,呈典型的凋亡形态学改变;TUNEL法及FCM检测结果显示,经不同浓度白桦酯醇处理24 h后,HeLa细胞发生凋亡,且随药物浓度的增加凋亡率明显增高；蛋白质印迹法检测结果显示,随加药浓度的增加,HeLa细胞中caspase-3和PARP蛋白表达均呈不同程度的上调.结论:在一定的浓度范围内,白桦酯醇可在体外抑制Hela细胞增殖并诱导其凋亡,其作用机制可能与其上调caspase-3及PARP蛋白的表达有关.

Betulin induces apoptosis of HeLa cell lines in vitro and its possible mechanism

Objective: To investigate the apoptosis of human cervical cancer HeLa cells induced by betulin in vitro, and to explore its possible mechanism. Methods: The HeLa cells were treated with betulin at different concentrations for 24, 48 and 72 h, and the inhibitory rate of cell proliferation was assessed by MTT method. The morphological changes of HeLa cells were examined by a phase contrast microscope. The TUNEL assay was used to detect the apoptosis of HeLa cells. The apoptotic rate was detected by flow cytometry (FCM). The expression levels of caspase-3 and poly (ADP-ribose) polymerase (PARP) proteins were analyzed by Western blotting. Results: The proliferation of HeLa cells was inhibited via treatment with different concentrations of betulin in a dose- and time-dependent manner (P < 0.01). After treatment with betulin for 24 h, the HeLa cells became smaller with karyopycnosis and weak refraction under a phase contrast microscope. These morphological changes of apoptosis were more obvious with the increase of betulin concentration. The results of TUNEL and FCM showed that the apoptosis of HeLa cells induced by different concentrations of betulin for 24 h was induced, and the apoptotic rate of HeLa cells was increased in a dose-dependent manner. The Western blotting result showed that the expression levels of caspase-3 and PARP proteins were up-regulated with the increase of betulin. Conclusion: In a certain concentration range, betulin can inhibit the proliferation of HeLa cells and induce the apoptosis in vitro. This effect may be associated with the up-regulated expressions of caspase-3 and PARP proteins.