Abstract: Objective: To explore the changes of chemotherapy sensitivity of breast cancer MCF-7/ADM cells afterHiwi gene targeting silence, and to illuminate the role of Hiwi gene in resistant mechanism of breast cancer MCF-7/ADM cells.Methods: The MCF-7/ADM cells were transfected with Hiwi control,siRNA1 Hiwi gene and siRNA2 Hiwi gene as Hiwi control group, Hiwi siRNA1 group and Hiwi siRNA2 group.The expression levels of Hiwi gene mRNA and protein in breast cancer MCF-7/ADM cells were detected by Real-time PCR and Western blotting methods to judge the transfection rates in various groups.After transfection,the breast cancer MCF-7/ADM cells invarious groups were treated with the different concentrations(0,0.1,0.5 and 1.0 mg·L^-1) of adriamycin, and the cell resistant sensitivities were detected by MTT method.Results: Compared with control group(0 mg·L^-1 adriamycin), the expression levels of Hiwi gene mRNA and protein inMCF-7/ADM cells in Hiwi siRNA1 and Hiwi siRNA2 groups were significantly decreased (P<0.01).Compared with control group, the survival rates of Cells in Hiwi siRNA1 and Hiwi siRNA2 groups were significantly decreased after treated with different concentrations of adriamycin,and the survival rates in Hiwi siRNA1 and Hiwi siRNA2 groups were significantly decreased(P<0.01);they were (48.15±6.28)% and (41.73±6.17)% when the concentration of adriamycin was 1 mg·L^-1,and the sensitivities to the adriamycinwere obviously enhanced(P<0.01).Conclusion: The target silencing Hiwi genes in MCF-7/ADM cells is efficient.The sensitivity of MCF-7/ADM cells to adriamycin restores after Hiwi gene silencing.

Key words: Hiwigene, targeted silence, sensitivity, breast neoplasms, MCF-7/ADM cells