米非司酮诱导雄激素非依赖性前列腺癌细胞凋亡的实验研究

目的探讨米非司酮在体外诱导雄激素非依赖性前列腺癌DU-145、PC-3细胞凋亡的作用。方法采用四甲基偶氮唑蓝法检测1,10,50和100μmol／L米非司酮作用于前列腺癌DU-145、PC-3细胞24～120h的吸光度（A）值,用流式细胞仪检测10μmol／L米非司酮作用24和48h后DU．145、PC-3细胞凋亡率的变化;采用免疫组化法检测米非司酮作用DU-145、PC．3细胞后bax、bcl-2、血管内皮生长因子（VEGF）蛋白表达的变化。结果1μmol／L米非司酮组的A值与对照组相比,差异无统计学意义（P〉0．05）;10,50和100μmol／L米非司酮组的A值与对照组比较,差异有统计学意义（P〈0．01）;米非司酮对前列腺癌DU-145、PC-3细胞的抑制作用呈时间-剂量依赖性。10μmol／L米非司酮作用前列腺癌DU-145细胞24和48h的凋亡率分别为15．3％和30．4％,PC-3细胞的凋亡率分别为22．2％和32．0％。经10μmol／L米非司酮作用后,DU-145、PC-3细胞中VEGF和bcl-2蛋白的表达明显减少,而bax的表达显著增加（P〈0．05）。结论米非司酮以时间．剂量依赖性方式抑制激素非依赖性前列腺癌DU-145和Pc-3细胞的增殖,其作用可能是通过降低VEGF蛋白的表达。从而下调bcl-2、激活bax蛋白的表达来实现。

Induction of apoptosis by mifepristone in androgen-independent prostate cancer cell lines in vitro

OBJECTIVE: To investigate the effects of mifepristone on cell proliferation of human androgen-independent prostate carcinoma cell lines DU-145, PC-3 in vitro and the possible mechanisms involved. METHODS: The A values of the prostate cancer cells DU-145 and PC-3 in each group with various concentrations (1, 10, 50, 100 micromol/L) of mifepristone at various time intervals (24-120 h) were detected with the colorimetric 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl tetrazolium bromide assay. The apoptosis rates of the DU-145 and PC-3 cells treated with 10 micromol/L of mifepristone for 24 h and 48 h were assessed by flow cytometry analysis technique. Immunohistochemical technique was used to determine the expression of bax, bcl-2 and vascular endothelial growth factor (VEGF) proteins after treatment with 10 micromol/L of mifepristone. RESULTS: The A values of the cancer cells treated with 1 micromol/L of mifepristone were similar to that of controls, while those of the cells treated with 10 micromol/L, 50 micromol/L and 100 micromol/L of mifepristone were significantly different from that of controls (P < 0.01). Mifepristone markedly inhibited cell proliferation of prostate cancer cells DU-145 and PC-3 on a dose- and time-depending manner. The apoptosis rates of 10 micromol/L mifepristone for DU-145 cell line at 24 h, 48 h were respectively 15.3%, 30.4% with flow cytometry method and then PC-3 cell line were respectively 22.2%, 32.0%. Immunohistochemical technique showed the expression of bcl-2 and VEGF in the DU-145 and PC-3 cells treated with 10 micromol/L of mifepristone were significantly decreased, and the expression of bax was increased. CONCLUSIONS: Mifepristone can induce apoptosis of androgen-independent prostate cancer cell lines DU-145 and PC-3 in vitro. The apoptosis effect is time-and-dose dependent. Mifepristone could initiate a cell death command via apoptotic pathways decreasing the expression of VEGF protein, downregulating the expression of bcl-2 protein and increasing the expression of bax protein.