RelB在蛋白酶体抑制剂诱导的maspin表达中的作用研究

Effect of RelB on proteasome inhibitor-induced maspin expression

目的:探讨前列腺癌细胞中,核转录因子NF-κB家族成员之一RelB在蛋白酶体抑制剂作用下maspin蛋白表达调控中的作用机制。方法:采用Western blotting法检测前列腺癌细胞中内源性及蛋白酶体抑制剂MG-132作用下RelA、RelB和maspin的蛋白表达;采用免疫组化法检测前列腺癌组织中RelB和maspin的表达情况;通过转染小分子RNA至前列腺癌细胞中沉默RelB的表达;采用Western blotting法检测RelB沉默对MG-132诱导的maspin蛋白表达情况的影响;PI染色法结合流式细胞术检测细胞死亡率。结果:雄激素非依赖型前列腺癌细胞DU145中RelB表达增强而maspin表达明显降低。在检测的10例前列腺癌组织样本中,恶性度高(Gleason评分4-5)的样本普遍同时存在胞核内RelB强染色和maspin表达缺失。MG-132作用DU145细胞24 h后RelB在胞浆和胞核中表达水平下调,伴随着maspin在胞核内的表达上调。MG-132处理RelB表达沉默的DU145细胞8和24 h后,maspin的表达无明显变化,而RelA蛋白的表达水平呈时间依赖性的下调。结论:在雄激素非依赖型前列腺癌细胞和晚期前列腺癌组织中,maspin与RelB的表达呈负相关性。蛋白酶体抑制剂诱导maspin的表达上调过程中,RelB是重要的调控因子。

AIM： To investigate the effects of RelB on proteasome inhibitor-induced maspin expression in prostate cancer cells.METHODS： Western blotting analysis was performed to examine endogenous and proteasome inhibitor（MG-132）-induced expression of RelA,RelB and maspin in prostate cancer cells.The expression profiles of RelB and maspin in human prostate cancer tissues were obtained by immunohistochemistry assay.RNA interference targeting RelB was performed in DU145 cells.The effects of RelB-silencing on maspin expression induced by MG-132 were detected by Western blotting.The cell viability was determined by PI staining and FACS analysis.RESULTS： RelB expression was increased in androgen-independent prostate cancer cell line DU145,while maspin expression was minimally detected.Among 10 tissue samples tested,a strong nuclear RelB staining and an absence of maspin expression were found in high-grade specimens（Gleason scores 4-5）.RelB expression was reduced upon treatment with MG-132 for 24 h,which was coincided with the induction of maspin expression.RelB-silencing in DU145 cells by siRNA didn＇t influence the proteasome inhibitor-induced maspin expression.CONCLUSION： The expression of RelB is inversely correlated to maspin expression in androgen-independent prostate cancer cells and prostate cancer tissues.RelB expression is critical to the proteasome inhibitor-induced maspin expression.