MDR1及MDR3短发夹RNA逆转乳腺癌细胞阿霉素耐药的实验研究

目的 研究靶向多药耐药(MDR)1及MDR3基因的短发夹RNA(shRNA)在逆转人乳腺癌阿霉素耐药细胞株MCF-7/Adr耐药中的作用.方法 真核质粒介导的针对MDR1及MDR3基因的shRNA转染细胞,空载体转染作为对照.Annexin-Ⅴ和PI双标法、流式细胞术、四甲基偶氮唑蓝(MTT)、逆转录聚合酶链反应(RT-PCR)、免疫组化分别检测细胞凋亡、细胞内阿霉素蓄积、细胞增殖活性及对阿霉素的IC50、MDR1及MDR3 mRNA及P-糖蛋白(P-gp)表达.结果 转染后,MDR1组及MDR3组MCF-7/Adr细胞凋亡率分别为30.21%±1.65%和22.07%±2.17%,与未转染组和空载体转染组比较差异有统计学意义(P＜0.01);MCF-7/Adr细胞内的阿霉素积聚浓度显著增加;MCF-7/Adr细胞存活率显著下降,MCF-7/Adr细胞对阿霉素IC50显著降低;相对于空载体转染组,MCF-7/Adr细胞中MDR1和MDR3 mRNA最高分别下降89.5%±0.8%和85.1%±1.2%,mRNA下降水平与孵育时间有关;P-gp表达明显降低,与未转染组和空载体转染组比较差异有统计学意义(P＜0.05).结论 shRNA可特异性地沉默MDR1及MDR3基因的表达,逆转P-gp介导的乳腺癌细胞阿霉素耐药,而MDR1的这种作用更为显著.

Reversal effect of MDR1 and MDR3 gene silencing by shRNA on resistance of breast carcinoma cells to adriamycin

Objective To investigate the effect of MDR1 and MDR3 gene silence by shRNA of human breast carcinoma cell line MCF-7/Adr,and explore the role of MDR1 and MDR3 in adriamycin-resistance of breast carcinoma cells. Methods shRNA plasmid vector specifically targeting MDR1 and MDR3 gene was transfected into cells. The control group was transfected with empty vector. The concentration of adriamycin was detected by the flow cytometry (FCM). Cell apoptosis was analysed by FITC-Annexin-V/PI double staining. Cell viability and the IC50 of adriamycin on MCF-7/Adr cells were determined by MTT method. MDR1 and MDR3 mRNA were assessed by RT-PCR. P-gp expression was detectedby immunochemistry. Results After treatment with ABCB1 and ABCB4 shRNA plasmid vector, the apoptosis of MCF-7/Adr cells was (30.21±1.65)%and (22.07±2.17)% respectively. Compared with untransfecedgroup and empty vector transfection group the difference was significant(P＜0.01). MDR1 and MDR3 shRNAcould increase cellular adriamycin accumulation of MCF-7/Adr cells. MCF-7/Adr cells viability and the IC50were significantly decreased after transfection. Compared with untransfeced group and empty vector transfectiongroup, the mRNA level of MDR1 and MDR3 in MCF-7/Adr cells were decreased by (89.5±0.8)%and(85.1±1.2)%, the reduction of MDR1 and MDR3 mRNA was in a time-dependent manner. Immunochemistry proved that the expression of p-gp was significantly inhibited. Compared with untransfeced group and empty vector transfection group the difference was significant (P＜0.05). Conclusion The shRNA can effectively and specifically silence the expression of MDR1 and MDR3 gene, reverse the adriamycin-resistance mediated by P-gp in MCF-7/Adr cells. The reversal effect of adriamycin-resistance by shRNA of MDR1 is more effective than that of MDR3.