17β-雌二醇逆转乳腺癌耐药蛋白介导的多药耐药机制

THE STUDY OF THE MECHANISM OF 17β-ESTRADIOL ON REVERSAL OF THE BREAST CANCER RESISTANT PROTEIN-MEDIATED MULTIDRUG RESISTANCE

目的探讨17β-雌二醇逆转乳腺癌耐药蛋白(BCRP)介导的非典型多药耐药的机制。方法分别通过药物诱导和转基因的方法建立由BCRP和巨细胞病毒(CMV)启动子启动表达BCRP的两种耐药细胞系MCF-7/MX20和MCF-7/BCRP,将耐药细胞培养在含有17β-雌二醇的培养基中,通过细胞毒性实验,外排实验以及定量PCR观察对不同耐药细胞系的逆转作用。结果培养基中加入17β-雌二醇48h后,MCF-7/BCRP细胞中的米托蒽醌的强度明显低于MCF-7/MX20,MCF-7/BCRP细胞中BCRP mRNA的含量明显高于MCF-7/MX20。17β-雌二醇可以抑制细胞中BCRP的表达和功能,但是不能抑制MCF-7/BCRP细胞中BCRP的表达和功能。结论17β-雌二醇不是作为BCRP的底物而抑制BCRP功能的,而可能是通过调控BCRP基因的启动子发挥作用。

Objective To explore the mechanism of the reversal of breast cancer resistant protein-mediated multidrug resistance by 17β-estradiol. Methods Two BCRP expressing cell lines of MCF-7/MX20 and MCF-7/BCRP were established in which breast canrcer resistant protein（BCRP） was promoted by BCRP promoter and cytomegalovirus（CMV） promoter respectively, These drug resistant cell lines were cultured in medium containing 17β-estradiol. Fourty-eight hours later, cytotoxicity assay, mitoxantrone efFlux assays, quantitative BT-PCR were performed to observe the reversal function of BCRP by 17β-estradiol on MCF- 7/MX20 and MCF-7/BCRP respectively. Results After being treated with 17β-estradiol,the intensity of mitoxantrone in MCF-7/ BCRP was weaker than that in MCF-7/MX20 and the BCRP mRNA level in MCF-7/BCRP was high than that in MCF-7/MX20.The results of these experiments revealed that 17β-estradiol could reverse the BCRP mediated multidrug resistance（MDR） in MCF-7/ MX20 cells but not in MCF-7/BCRP ones. Conclusion 17β-estradiol may reverse the phenotype of BCRP through regulation of the promoter of BCRP gene but not acted as the substrate of BCRP.