Effects of siRNA silencing the expression of FOXM1 gene on proliferation, apoptosis and chemosensitivity of human nasopharyngeal carcinoma cells / 肿瘤

ABSTRACT

Objective: To investigate the effects of silencing the expressionof Forkhead box M1 (FOXM1) gene by the specific siRNA on proliferation, apoptosis and chemosensitivity of human nasopharyngeal carcinoma cells, and to explore the molecular mechanisms. Methods: The specific siRNA fragments targeting FOXM1 gene (FOXM1-siRNA) was transfected into nasopharyngeal carcinoma 5-8F cells, then the silencing efficiency of FOXM1 gene expression was detected by RT-PCR, real-time fluorescent quantitative PCR and Western blotting, respectively. The changes of proliferation ability, cell cycle distribution, apoptosis rate, and paclitaxel sensitivity of 5-8F cells after FOXM1-siRNA transfection were detected by MTT assay, FCM, and AnnexinV-FITC/PI staining assay, respectively. The expressions of relative proteins in 5-8F cells with FOXM1 gene silencing were detected by Western blotting. Results: The expressions of FOXM1 mRNA and protein in 5-8F cells after FOXM1-siRNA transfection were significantly decreased (both P < 0.01). After FOXM1 gene silencing, the proliferation ability of 5-8F cells was decreased (P < 0.05), and the expression level of proliferating cell nuclear antigen (PCNA) protein was significantly decreased (P < 0.01). Meanwhile the proportion of cells in G1 phase after FOXM1 gene silencing was increased (P < 0.01), while the proportion of cells in S phase was decreased (P < 0.05), and the expression of Cyclin D1 was down-regulated (P < 0.01). The apoptosis rate of 5-8F cells with FOXM1 gene silencing was significantly increased (P < 0.01), the expression level of Bcl-2 was down-regulated (P < 0.01), and the expression level of Bax was up-regulated (P < 0.01). Furthermore, the sensitivity of 5-8F cells to paclitaxel was significantly enhanced (P < 0.01), and the expression of multidrug resistance-associated protein 1 (MRP1) was down-regulated (P < 0.01) after FOXM1-siRNA transfection. Conclusion: The specific siRNA silencing FOXM1 gene expression can effectively inhibit the proliferation of nasopharyngeal carcinoma 5-8F cells, promote cell apoptosis, and enhance the sensitivity to paclitaxel. These effects may be related to the down-regulation of PCNA, Cyclin D1, MRP1 and Bcl-2 expressions as well as the up-regulation of Bax expression in 5-8F cells.