孕酮调节乳腺癌耐药蛋白的机制研究

Progesterone modulates breast cancer resistance protein in breast cancer cells

目的:探讨孕酮调控乳腺癌耐药蛋白(BCRP)表达的机制。方法:通过米托蒽醌(MX)诱导或基因转染的方法,作用于孕酮受体(PR)阳性的T47D和PR阴性的MDA-MB-231乳腺癌细胞系,建立由BCRP启动子或巨细胞病毒(CMV)启动子启动表达BCRP的4种耐药细胞系T47D/MX、T47D/CMV-BCRP、MDA-MB-231/MX和MDA-MB-231/CMV-BCRP,将孕酮加入耐药细胞的培养液中,通过RT-PCR、Western blotting及MX外排实验观察其对不同耐药细胞系BCRP表达的影响。结果:孕酮可以剂量依赖方式明显上调PR阳性的乳腺癌细胞系T47D/MX中BCRP mRNA和蛋白的表达,细胞中MX的荧光强度明显减弱。而对照组T47D/CMV-BCRP、MDA-MB-231/MX和MDA-MB-231/CMV-BCRP细胞系,各组处理前后相比,BCRP的表达量无明显变化。结论:孕酮可能通过PR的介导与BCRP启动子上游调控序列中的孕激素反应元件(PRE)结合,激活BCRP基因的启动子而增强BCRP mRNA的转录,正性调节BCRP蛋白的表达和功能。

AIM： To investigate the regulatory effect of progesterone on breast cancer resistant protein（BCRP） in breast carcinoma cells.METHODS： The drug-resistant breast cancer cell lines were constructed by mitoxantrone（MX） induction step by step or recombinant plasmid transfection.The progesterone receptor（PR）-positive T47D and PR-negative MDA-MB-231 breast cancer lines were used.Four BCRP expressing cell lines T47D/MX,T47D/CMV-BCRP,MDA-MB-231/MX and MDA-MB-231/CMV-BCRP were established,in which BCRP was driven by a BCRP promoter,and a cytomegalovirus（CMV） promoter was used as control.The drug-resistant cells were treated with progesterone.The expression of BCRP at mRNA and protein levels was detected by RT-PCR and Western blotting,respectively.The function of BCRP was assessed by mitoxantrone efflux assay.RESULTS： Progesterone significantly up-regulated the BCRP expression at mRNA and protein levels in a dose-dependent manner in PR-positive T47D/MX cells.At the same time,the efflux function of BCRP was increased and the fluorescence intensity of mitoxantrone in T47D/MX cells was significantly decreased.As expected,no significant change of the BCRP level was observed in the control T47D/CMV-BCRP,MDA-MB-231/MX and MDA-MB-231/CMV-BCRP cells after treated with progesterone.CONCLUSION： BCRP expression is up-regulated by progesterone via a novel pre-transcriptional mechanism,which might be involved in the progesterone response element（PRE） of BCRP promoter through the PR-mediated classical pathway to activate the transcription of BCRP gene.