Study Of Reversal Effects On Multidrug Resistance In VCR-resistant Human Gastric Cancer Cell Line SGC7901/VCR By RNA Interference And Drugs

OBJECTIVE: To explore the reversal effect of targeted siRNA,verapamil andrecombinated epidermal growth factor (EGF) on multidrug resistance (MDR) invincristine (VCR)-resistant human gastric cancer cell line SGC7901/VCR and itsmechanisms.METHODS: Establish a VCR-resistant variant of human gastric cancer cells lineSGC7901 by cultivated with VCR, named SGC7901/VCR. The expression level ofMDR1 and TopoⅡαwere detected by RT-PCR. The level of P—glycoproteinand TopoⅡαprotein were evaluated by immunohistochemistry method. Thechemosensitivity of chemotherapeutic agents—vincristine, mitomycin, tegafur,adriamycin and daunorubicin was evaluated by the MTT assay.RESULTS:1,Establishing a vincristine (VCR)-resistant variant of human gastric cancer cellsline SGC7901 successfully.2,After transfected with siRNA, there comes: (1) The expression level of MDR1mRNA was knocked down by siRNA (the level of blank and the control was 0.759±0.035 and0.743±0.045, respectively. After interfered with siRNA, the level wasdecreased to 0.413±0.166, p＜0.01). (2) The expression of P-glycoprotein was downregulated by siRNA(It was(93±1)% and (92±1)% in blank and control group,respectively. After treated with siRNA, it decreased to (42±1)%, p＜0.01). (3) MTT indicted that the chemosensitivity was promoted by treated with siRNA.3,After treated with verapamil, there comes. (1) After treated with verapamil at10μmol/L,20μmol/L,40μmol/L and 80μmol/L for 24 hours, the expressionlevel of MDR1 mRNA was inhibited, especially in the group of 80μmol/L. (2)After treated with verapamil at 10μmol/L,20μmol/L,40μmol/L and 80μmol/Lfor 24 hours, the expression of P-gp was down regulated by verapamil. (3) MTTshowed that the sensitivity to anticancer agents were promoted by verapamil.4,After treated with EGF, there comes: (1) After treated with EGF at 0.2μg/mland 2μg/ml, the Expression level ofTopoisomeraseⅡα(TopoⅡα) mRNA wasup regulated. (2) After treated with EGF at 0.2μg/ml and 2μg/ml, the expression ofTopoⅡαprotein was reinforced by EGF. (3)MTT indicated that thechemosensitivity was promoted by EGF.5,There were no difference among siRNA, Verapamil (80μmol/L) and EGF(2μg/ml) on reversing the MDR in SGC7901/VCR.CONCLUSION: siRNA, verapamil and EGF can reverse the MDR ofSGC7901/VCR.