中文摘要：

目的研究BRCA1能否存乳腺癌细胞中调节黄体酮受体A和B的表达。方法在乳腺癌细胞MCF-7中，用lipofectamine2000转染含有野生型BRCA1 cDNA的pFlag—CMV2-BRCA1 wt质粒或BRCA1特异性的小干扰RNA，过表达BRCA1或敲低BRCA1的表达。转染24h以后，加入含有100nmol／L黄体酮完全培养基刺激24h。提取全细胞蛋白或总RNA，进行Western blotting和RT—PCR检测BRCA1、黄体酮受体A（PRA）和黄体酮受体B（PRB）在蛋白质水平和mRUA水平的表达。结果在MCF-7细胞中过表达BRCA1，PRA和PRB蛋白的表达下降，而PRA和PRB在mRNA水平无变化：BRCA1的表达被敲低后，PRA和PRB的表达升高。结论在乳腺癌细胞中，外源性和内源性BRCA1都可以下调PRA和PRB蛋白的表达。

英文摘要：

Objective To study the regulatory role of BRCAI in the expression of progesterone receptors A and B （PRA and PRB） in breast cancer cells. Methods Breast cancer MCF-7 cells were transfected with pFIag-CMV2-BRCA1 wt plasmid containing a full-length BRCAI cDNA or with BRCA1-specific siRNA via lipofectamine 2000 to induce overexpression or suppressed expression of BRCA1, respectively. Twenty-four hours after the transfection, the cells were incubated in flesh culture medium containing 100 nmol/L progesterone for 24 h. The total RNA extract or whole cell lysate was prepared for detecting BRCAI, PRA and PRB expressions using RT-PCR and Western blotting. Results The protein expressions of PRA and PRB were significantly decreased whereas their mRNA expressions remained unchanged in MCF-7 cells overexpressing BRCAI. In MCF-7 cells with BRCA1 knock-down, in contrast, the PRA and PRB protein expressions were markedly increased. Conclusion In breast cancer cells, exogenous and endogenous BRCA1 can both down-regulate the expressions of PRA and PRB at the protein level.