Influence of human epidermal growth factor receptor-2 siRNA on chemosensitivity to cisplatin of human ovarian carcinoma cells: An in vitro experiment

Objective: To investigate the effects of RNA interference (RNAi) targeting human epidermal growth factor receptor 2 (HER-2) gene on the change of chemosensitivity to cisplatin of ovarian carcinoma cells. Methods: Three kinds of HER-2 gene targeting siRNA, HER-2 siRNA I - III, were synthesized and the best one (HER-2 siRNA III) was screened. Human ovarian carcinoma cells of the line SKOV3 were cultured randomly divided into 3 groups: HER-2 siRNA III group, transfected with HER-2 siRNA III, non-specific siRNA group, transfected with non-specific siRNA III, and control group, without transfection. Cisplatin of the concentrations of 0, 0.05, 0.2. 0.4, 0.8, 1.0, 2.0, 10, and 20 μg/ml was added into the culture fluid for 24 h. MTT method was used to detect the proliferation rate of the SKOV3 cells. Other SKOV3 cells were divided into 3 groups: siRNA group, transfected with HER-2 siRNA III, cisplatin group, exposed to cisplatin, and HER-2 siRNA III and exposed to cisplatin. Annexin V method and flow cytometry were used to detect the apoptosis of the SKOV3 cells. The HER-2 gene expression was assessed by Western blotting. The chemosensitivity of transfected cells to cisplatin was measured by MTT. Western blotting was used to detect the protein expression of apoptosis related proteins: Bcl-2, surviving, XIAP, and Smac. Results: After exposed to cisplatin, the cell survival rate decreased as the dose of cisplatin increased. The proliferation rate of the SKOV3 cells transfected with HER-2 siRNA III and exposed to 1 μg/ml cisplatin was (58 ± 5) %, significantly lower than those of the nonspecific siRNA III transfection group [(65 ± 6)%] and the control group [(68 ± 3)%, both P < 0. 01]. No significant difference in the cell survival rate was found between the control and nonspecific groups (P > 0. 05). The apoptosis rates at different time point of the HER-2 siRNA III + cisplatin group were all higher than those of the other 2 groups (all P < 0.01). The protein expression levels of the antiapoptotic proteins Bcl-2, survivin,and XIAP were of the HER-2 siRNA III + cisplatin group were significantly lower than those of the cisplatin group, and the protein expression level of the apoptotic protein Smac of the HER-2 siRNA III + cisplatin group significantly higher than that of the cisplatin group (all P < 0.05). Conclusions: HER-2 siRNA III induces cell apoptosis significantly and increases the sensitivity of the human ovarian carcinoma cells to cisplatin. The mechanism of induction of cell apoptosis by HER-2 siRNA III + cisplatin may be related to the downregulation of Bcl-2, survivin and XIAP protein and the up-regulation of Smac protein.