[Reversal of multi-drug resistance in ovarian cancer cell by RNA interference]

To investigate the effects of small interference RNA (siRNA) on the inhibition of MDR1 mRNA and P-gp expression of ovarian cancer cells with high expression of MDR1 gene, and reversal of drug resistance.siRNA was synthesized and transfected into human ovarian cancer cell line OVCAR8/TR by liposome. The expression of MDR1 mRNA at different times after transfection was measured by real time RT-PCR and the P-gp expression was detected by flow cytometry. Adenosine triphosphate (ATP)-bioluminence assay was applied to check the drug sensitivity to four different chemotherapeutic agents before and after transfection.The suppression rates of MDR1 mRNA were 26.42%, 84.00%, 78.43%, 45.85% and 0 respectively at 24, 48, 72, 96 and 120 hours after transfection. The P-gp suppression rates were 16.71%, 49.64%, 85.23%, 65.98%, 9.44% respectively at 24, 48, 72, 96 and 120 hours after transfection. The maximal suppression rates of MDR1 mRNA and P-gp occurred at 48 and 72 hours after transfection respectively. ATP-bioluminence assay showed that OVCAR8/TR cells were sensitive to fluorouracil, resistant to cisplatin, doxorubicin (adriamycin) and paclitaxel (taxol). After siRNA treatment, OVCAR8/TR cells were sensitive to paclitaxel and doxorubicin, but the resistance to cisplatin could not be reversed.RNA interference (RNAi) presents in human ovarian cancer cells. siRNA can effectively inhibit the expression of mRNA and P-gp of the multidrug resistance gene MDR1, and can reverse the drug resistance to chemotherapeutic agents which are transferred by P-gp.