β-谷甾醇对子宫颈癌细胞微管系统的影响

目的 探讨β-谷甾醇对子宫颈癌细胞SiHa的生长抑制作用及对细胞内微管系统的影响。方法 采用四甲基偶氮唑蓝（MTT）法测定β-谷甾醇对SiHa细胞的增殖抑制作用,并用流式细胞技术分析β-谷甾醇作用前后细胞周期的变化,应用激光共聚焦显微技术观察β-谷甾醇处理的SiHa细胞内微管和微管相关蛋白2的表达、分布,采用蛋白免疫印迹法检测微管蛋白、微管相关蛋白2的表达,及聚合和未聚合微管蛋白含量的变化。结果 20μmol／L的β-谷甾醇能明显抑制SiHa细胞的增殖,并显著促进S期细胞的集聚。激光共聚焦分析表明,β-谷甾醇作用5d的SiHa细胞微管网络异常,微管相关蛋白2表达显著下调,蛋白免疫印迹结果进一步证实β-谷甾醇能抑制微管蛋白α和微管相关蛋白2的表达,同时β-谷甾醇能抑制SiHa细胞内微管蛋白的聚合,并随着作用时间的延长而逐渐增强。结论 β-谷甾醇能降低SiHa细胞微管蛋白α和微管相关蛋白2的表达,并抑制SiHa细胞内微管的聚合,提示β-谷甾醇具有一定的抗微管作用,这一作用可能是造成SiHa细胞生长抑制的重要原因。

Effects of beta-sitosterol on microtubular systems in cervical cancer cells

OBJECTIVE: To investigate beta-sitosterol's inhibitory effects on SiHa cells' growth, and the effects on microtubular system in SiHa cell. METHODS: Proliferation inhibition of SiHa cell line was evaluated by MTT assay. Cell cycle of SiHa cells treated with beta-sitosterol was analyzed by flow cytometry. The expression and distribution of microtubule and microtubule associated protein 2 in SiHa cells were investigated by confocal microscopy. Immunoblotting analysis was used to determine tubulin alpha, microtubule associated protein 2, and the proportion of polymerization of tubulin. RESULTS: beta-sitosterol could obviously inhibit the proliferation of SiHa cells, and induce the accumulation of cells in S phase (rather than the G2/M phase) and mitotic arrest in the cell cycle. Confocal microscopy showed an abnormal microtubular network in SiHa cell treated with beta-sitosterol for 5 days, and the expression of microtubule associated protein 2 was marked down-regulated. Further analysis by immunoblotting confirmed the down-regulation of beta-sitosterol on the expression for both microtubule associated protein 2 and tubulin alpha. Moreover, beta-sitosterol reduced the proportion of polymerization of microtubule in a time-dependent manner. CONCLUSION: beta-sitosterol could down-regulate the expression of tubulin alpha and microtubule associated protein 2 in SiHa cells, and inhibit the microtubular polymerization. Our results suggested an anti-microtubule characteristic of beta-sitosterol which might contribute to the proliferation inhibition of SiHa cells.