RNAi抑制肾癌细胞MDR1基因表达及对顺铂化疗耐药的逆转

Suppression of MDR1 gene expression and reversal of cisplatin resistance in renal carcinoma cells by RNA interference

目的:研究RNA干扰(RNA interference,RNAi)对肾癌细胞多药耐药基因1(multidrug resistance,MDR1)表达的抑制作用,并分析干扰前后肾癌细胞对顺铂(cisplatin)敏感度的变化。方法:根据MDR1基因序列设计3条小干扰RNA(small in-terfering RNA,siRNA),转染肾癌A498细胞;RT-PCR法检测转染前后MDR1 mRNA表达水平的变化,筛选出干扰效率最高的siRNA序列;进而利用慢病毒包装siRNA重组质粒,感染A498细胞,RT-PCR法筛选沉默效果最好的细胞株进行克隆;Western印迹法检测MDR1蛋白表达水平;MTT法检测干扰前后顺铂对半数细胞抑制浓度(half inhibitory concentration,IC50)的变化。结果:3条siRNA序列均能不同程度地抑制细胞MDR1基因的表达,其中siRNA-1序列能更有效地封闭MDR1基因,使MDR1 mRNA表达水平下降67%;筛选得到稳定转染的细胞株与未干扰细胞株相比,MDR1蛋白表达量明显下降(P<0.01),并使顺铂对细胞的IC50值降低约83.37%(P<0.01)。结论:RNAi能有效抑制肾癌A498细胞MDR1基因的表达,并可显著增加其对顺铂的敏感度,从而使肾癌细胞化疗耐药逆转成为可能。

Objective：To investigate the inhibitory effect of RNA interference （RNAi） on the expression of multidrug resistance （MDR1） gene and analyze the altered sensitivities of human renal carcinoma cell line to cisplatin.Methods：Three small interfering RNA （siRNA） sequences targeted MDR1 gene were synthesized and transfected into renal carcinoma A498 cells. The expression level of MDRl mRNA was measured by RT-PCR to identify the most effective siRNA sequence. The recombinant plasmid was packed by lentivirus and transfected into A498 cells. RT-PCR was used to screen the A498 cells with the optimal silencing efficacy. The MDR1 protein expression level in the cloned cells was verified by Western blotting. The inhibitory effect of cisplatin on the proliferation of A498 cells was assessed by MTT assay and the IC50 value was calculated. Results：The 3 siRNA sequences suppressed MDR1 gene expression at different degrees. The siRNA 1 sequence silenced MDR1 gene more effectively with a significant reduction of 67%. The MDR1 protein expression greatly decreased in screened A498 cells compared with non-transfected cells （P〈0.01）,and the IC50 value of cisplatin on screened A498 cells was significantly decreased by 83.37% （P〈0.01）. Conclusion：The RNAi could effectively inhibit the expression of MDR1 gene and increase the sensibility to cisplatin in human renal carcinoma A498 cell line,which make it possible to reverse the resistance of renal carcinoma to chemotherapy.