雄激素受体在前列腺癌细胞激素非依赖转化中的表达及调控

Expression and regulation of androgen receptor in the androgen-independent conversion of prostate cancer cells

目的:研究雄激素受体(androgen receptor,AR)在激素依赖性前列腺癌(androgen dependent prostate can-cer,ADPC)细胞系LNCaP转化成激素非依赖性前列腺癌(androgen independent prostate cancer,AIPC)过程中的表达变化,以及其受Wnt信号通路和蛋白酶体降解通路调控的机制。方法:应用活性炭滤过的低激素胎牛血清培养LNCaP细胞,得到雄激素非依赖的LNCaP亚系LNCaP-AI(androgen independent)细胞。应用细胞增殖试验检测LNCaP-AI的细胞生长曲线。应用Western blot、RT-PCR分析激素依赖性转化过程中的AR、前列腺特异抗原(pros-tate specific antigen,PSA)的表达变化。在AIPC细胞中,应用Wnt信号通路阻滞剂IWR-1及蛋白酶体通路抑制剂乳胞素(lactacystin)处理细胞,观察Wnt信号通路和蛋白酶体信号通路对AR mRNA及蛋白表达的影响。结果:在体外低激素环境中生长6个月后,LNCaP细胞变成雄激素非依赖性的LNCaP亚系LNCaP-AI。表现为对雄激素依赖性减弱,细胞增殖加快,PSA的表达增高。在转化为LNCaP-AI的过程中,AR mRNA水平短期上调,后恢复到原始水平,但蛋白水平一直处于下调趋势。IWR-1处理的LNCaP-AI,AR mRNA及蛋白的表达下调。乳胞素处理的LNCaP-AI,AR mRNA无变化而蛋白表达上调。结论:在体外前列腺癌细胞由激素依赖性向非依赖性转化的过程中,AR mRNA表达仅有一过性增高,而蛋白表达呈现明显的下降趋势。进一步研究发现,Wnt信号通路和蛋白酶体通路可能对AR的蛋白表达有调控作用。Wnt信号通路的抑制或蛋白酶体信号通路的增强可能是AR蛋白表达下调的原因。

Objective： To investigate the expression and regulation of androgen receptor（AR） in prostate cancer cells from androgen dependent to androgen independent.Methods： LNCaP cells were cultured in charcoal-stripped serum for 6 months to establish androgen-independent celline（LNCaP-AI）.Proliferation of LNCaP-AI was assayed by cell viability.Expression of AR mRNA and protein was analyzed by RT-PCR and Western blot.Wnt signaling pathway inhibitor IWR-1 and proteasome inhibitor lactacystin were used to investigate effects of Wnt and proteasome pathway on AR expression in LNCaP-AI.Results： LNCaP-AI exhibit enhanced proliferation and up-regulated PSA expression compared with LNCaP.During androgen deprivation,AR mRNA was up-regulated in a short early stage and then declined to a stable level in LNCaP-AI compared with LNCaP,but AR protein kept in downward trend.The mRNA and protein expression of AR was decreased by IWR-1 treatment.AR protein but not mRNA was increased by lactacystin treatment.Conclusion： The androgen independent prostate cancer cellline was established by androgen deprivation,in which the protein expression of AR was dramatically decreased.mRNA and protein expression of AR in LNCaP-AI was related to Wnt signaling pathway and proteasome pathway.Increased Wnt signaling or decreased proteasome pathways contribute the decreased AR protein expression.