紫花牡荆素对肝癌细胞凋亡的影响及其机制研究

目的研究紫花牡荆素(casticin)诱导肝癌细胞凋亡的作用及其分子机制。方法体外培养人肝癌PLC/PRF/5和HepG2细胞系。通过碘化丙啶(PI)染色流式细胞术分析细胞凋亡率,ELISA法检测组蛋白/DNA碎片的含量,琼脂糖凝胶电泳观察DNA断裂条带,Western blotting检测细胞内DR4和DR5蛋白表达水平。结果 Casticin以浓度依赖方式增加PLC/PRF/5和HepG2细胞系sub-G1细胞的百分率和组蛋白/DNA片段的含量(P<0.05),casticin(30μmol·L-1)作用细胞24h后可出现DNA梯度条带;casticin可以浓度依赖性方式诱导PLC/PRF/5内DR5蛋白水平的表达,但对DR4蛋白表达无影响;DR5/Fc嵌合蛋白预处理能有效降低casticin诱导的细胞凋亡。结论 Casticin可以浓度依赖性方式诱导肝癌细胞凋亡,其机制可能与上调细胞的DR5蛋白表达有关。

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Objective To investigate the effects and molecular mechanisms of casticin-induced apoptosis in hepatocellular carcinoma cells. Methods PLC/PRF/5 and Hep G2 cell lines were cultured in vitro. The apoptosis rate was analyzed by propidium iodide(PI) staining flow cytometry, and the histone/DNA fragment level was measured by ELISA detection kit. DNA fragmentation was detected by agarose gel electrophoresis, and the expressions of DR4 and DR5 proteins were analyzed by Western blotting. Results Casticin increased the percentage of sub-G1 and histone/DNA fragment level in PLC/PRF/5 and Hep G2 cell lines in a concentration-dependent manner(P<0.05). Treatment with 30 μmol/L casticin for 24 h resulted in the formation of a DNA ladder. Casticin also increased the expression of DR5 in PLC/PRF/5 cell line in a concentration-dependent manner, but it had no effect on the expression of DR4. Pretreatment with DR5/Fc chimera protein effectively attenuated the apoptosis induced by casticin. Conclusion Casticin induced apoptosis of HCC cells in a concentration-dependent manner. Its mechanism may be related with its role in upregulating the expression of DR5.