Tao Zhang1, Ming Guan, Hong Yan Jin, Yuan Lu. 1. Center of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200040, China.
Abstract
OBJECTIVE: Cisplatin (DDP) resistance is a major barrier to overcome before chemotherapy can become curative for most patients presenting with ovarian cancer. In this study, we investigated the effect of siRNAs on expression of p-gp, GST-pi mRNA and protein in cisplatin-resistant human ovarian cancer cells in order to restore sensitivity to DDP. METHODS: Small interfering double-stranded RNAs (siRNA) were designed to target p-glycoprotein (p-gp) and glutathione S-transferases (GST) mRNA as a strategy to inhibit both resistant gene expression at the mRNA level. Using Real-Time PCR and western blotting assay the changes of the RNA and protein levels of both drug resistant genes were studied. RESULTS: Transfection of MDR-1 and GST siRNAs into human multi-drug resistance (MDR) ovarian cancer cell lines, COC1/DDP and SKOV3/DDP, resulted in a time-dependent inhibition of both gene expressions with the decline of the IC(50) values but had no effect on the expression of a-Tubulin. Inhibition of P-gp and GST expression by siRNA enhanced the intracellular accumulation of and restored sensitivity to DDP. CONCLUSIONS: These studies suggest that p-gp and GST siRNAs are effective inhibitors of MDR gene expression and reverse the resistance of ovarian carcinomas. Our studies may provide a new insight to develop siRNAs as a novel therapeutic tool for the treatment of ovarian carcinomas.
OBJECTIVE:Cisplatin (DDP) resistance is a major barrier to overcome before chemotherapy can become curative for most patients presenting with ovarian cancer. In this study, we investigated the effect of siRNAs on expression of p-gp, GST-pi mRNA and protein in cisplatin-resistant humanovarian cancer cells in order to restore sensitivity to DDP. METHODS: Small interfering double-stranded RNAs (siRNA) were designed to target p-glycoprotein (p-gp) and glutathione S-transferases (GST) mRNA as a strategy to inhibit both resistant gene expression at the mRNA level. Using Real-Time PCR and western blotting assay the changes of the RNA and protein levels of both drug resistant genes were studied. RESULTS: Transfection of MDR-1 and GST siRNAs into human multi-drug resistance (MDR) ovarian cancer cell lines, COC1/DDP and SKOV3/DDP, resulted in a time-dependent inhibition of both gene expressions with the decline of the IC(50) values but had no effect on the expression of a-Tubulin. Inhibition of P-gp and GST expression by siRNA enhanced the intracellular accumulation of and restored sensitivity to DDP. CONCLUSIONS: These studies suggest that p-gp and GST siRNAs are effective inhibitors of MDR gene expression and reverse the resistance of ovarian carcinomas. Our studies may provide a new insight to develop siRNAs as a novel therapeutic tool for the treatment of ovarian carcinomas.