Effect of siRNA-mediated silencing metadherin on apoptosis of bladder cancer cells and its mechanisms

Objective To investigate the effect of siRNA-mediated silencing metadherin (MTDH) gene on apoptosis of bladder cancer cells and its mechanisms. Methods RT-PCR and Western blot were used to detect the expression of MTDH mRNA and protein in bladder epithelial immortalized SV-HUC-1 cells and human bladder cancer BIU-87 cells. MTDH gene was targeted silenced by liposomal transfection of MTDH-siRNA, and the silencing effect of MTDH and expression of B cell lymphoma/leukemia -2 gene(Bcl-2), Bcl-2 related X protein (Bax), p53 and phosphorylated Akt (p-Akt) were detected by RT-PCR and Western blot. The effect of MTDH gene silencing on apoptosis of BIU-87 cells was detected by flow cytometry. Results The mRNA and protein expressions of MTDH gene in human bladder cancer BIU-87 cells were significantly higher than those in bladder epithelial immortalized SVHUC-1 cells [(0.82±0.05) vs (0.25±0.03), (0.42±0.06) vs (0.18±0.05); P< 0.05, respectively]. Compared with NC group, the mRNA and protein expressions of MTDH2 in cells of siRNA MTDH2 group and their expressions of MTDH3 in cells of siRNA MTDH3 group decreased significantly [MTDH2: (0.31±0.03) vs (1.02±0.03), (0.29±0.02) vs (0.48±0.05); MTDH3: (0.22±0.05) vs (1.02±0.03), (0.18±0.08) vs (0.48±0.05); all P< 0.05], and the decrease in siRNA MTDH3 group was greater than that in siRNA MTDH2 group; While, there was no significant difference between siRNA NC group and siRNA MTDH1 group (P> 0.05).After silencing of MTDH, compared with NC group, the apoptosis rate of BIU-87 cells [(38.86%±2.52%) vs (9.95%±1.26%)], p53[(1.58±0.07) vs (0.61±0.04)] and Bax protein [(0.86±0.06) vs (0.43±0.03)] in siRNA MTDH group were significantly higher, while p-Akt protein [(0.31±0.03) vs (0.75±0.08)] and Bcl-2 protein [(0.35±0.08) vs (1.26±0.12)] decreased significantly, and the differences were all statistically significant (all P< 0.05), but the difference between NC group and siRNA NC was not significant(P> 0.05). Conclusion MTDH gene silencing may induce apoptosis of BIU-87 cells by up regulating the expression of p53, Bax protein and down regulating the expression of p-Akt, Bcl-2 protein.