Effect of Mir-34a on sensitivity of breast cancer cells MCF-7/ADR to adriamycin

OBJECTIVE:To evaluate the expression level of miR-34aand further investigate the potential influence on chemotherapy sensitivity by treating with adriamycin in MCF-7cells and MCR-7/ADR cells.METHODS:Mir-34aexpression level was determined by using Real-time PCR.Synthetic miR-34awas transfected into MCF-7/ADR cells with lipofectamine 2000vector.Drug resistance of cells was detected by MTT assay.The target genes expression of miR-34awas evaluating by Real-time PCR and western blot.RESULTS:Comparing with MCF-7cells(1.01±0.03),the expression level of miR-34ain MCF-7/ADR cells was 0.76±0.04(P=0.007)and which was lower than that of MCF-7cells.The IC50 of ADM in MCF-7and MCF-7/ADR cells was(0.22±0.02)μmol/L and(18.7±0.09)μmol/L,respectively.Up-regulation of miR-34a,the IC50 value of ADM in MCF-7/ADR cells decreased to(10.7±0.11)μmol/L.Moreover,compared with NC RNA transfection group,transfection of miR-34acould significantly down-regulate the mRNA level of Bcl-2(values were 0.46±0.02,P=0.002)and CCND1(values were 0.33±0.02,P=0.008)in MCF-7/ADR cells.Besides,western blot results showed that over-expression of miR-34acould significantly down-regulate the expression of Bcl-2and CCND1. CONCLUSION:The resistance on ADM of MCF-7/ADR cells is inhibited by miR-34agene up-regulating.