〔Abstract〕 Objective To investigate the effect of silencing SIRT1 gene by RNA interference on the radiosensitivity of human nasopharyngeal carcinoma cell line CNE-1,and to provide a new idea for clinical treatment of human nasopharyngeal carcinoma(PCN). Methods SIRT1 protein in NP69 and CNE-1 cells was detected by Western blot assay.The SIRT1-siRNA interference sequence was transfected into CNE-1 cells.The ability of cell proliferation was evaluated by CCK-8 assay.The cell apoptosis rate was detected by flow cytometry assay.The protein levels of Bcl-2,Bax,and Cleaved-Caspase3 were tested by Western blot assay. Results The results showed that the expression of SIRT1 protein in nasopharyngeal carcinoma tissues and cells was significantly higher than that of para-carcinoma tissues and NP69 cells(P<0.05).The expression levels of SIRT1 gene and SIRT1 protein in the cells of the transfection groups were significantly lower than that in the control group(P<0.05).The results showed after X-ray radiation of 4,6 and 8 Gy on CNE-1 cells,the ability of cell proliferation in the SIRT1 siRNA groups was obviously lower than that in the control group(P<0.01),and the cell apoptosis rate in the SIRT1 silence groups was significantly higher than that in the control group(P<0.01).Meanwhile,compared with the control group,the protein levels of Bax and Cleaved-Caspase3 significantly reduced,Bcl-2 expression significantly increased in SIRT1 siRNA group(P<0.05). Conclusion Silence of SIRT1 gene may enhance the sensitivity of CNE-1 cells to radiotherapy by inhibiting the proliferation and inducing apoptosis of CNE-1 cells,and SIRT1 gene may be a potential target for the treatment of nasopharyngeal carcinoma cancer.