Effects of NOX4 on radiosensitivity of nasopharyngeal carcinoma cells by activating the PI3K/AKT pathway

Abstract

Objective: To explore the relationship between NOX4 and radiosensitivity of nasopharyngeal carcinoma cells. Methods: Western blot was used to test the expression of NOX4 in nasopharyngeal carcinoma cells (CNE1, CNE2 and HONE1) and normal nasopharyngeal epithelial cells (NP69). The lentiviral vectors for RNA interference and overexpression of NOX4 gene were constructed and nasopharyngeal carcinoma cells were transfected. After treatment with radiation or/and PI3K/AKT inhibitor LY294002, the expressions of related proteins in cells were tested by Western blot, and the cell proliferation was detected by CCK-8 assay and the cell apoptosis was determined by flow cytometry. GraphPad Prism 5 was used for statistical analysis, and P<0.05 was statistically significant. Results: The expressions of NOX4 in nasopharyngeal carcinoma cells were higher than those in normal nasopharyngeal epithelial cells. Compared with the siNC group, the siNOX4 group of nasopharyngeal carcinoma cell had lower proliferation capacity [72 h absorbance (A) value:1.16 vs. 0.75] and higher apoptosis rate (2.9% vs. 10.0%). In contrast,compared with the vector group, the NOX4 group of nasopharyngeal carcinoma cell had higher proliferation capacity [72 h absorbance (A) value: 1.01 vs. 1.32] and lower apoptotic rate (1.7% vs. 1.1%).Treatment with LY294002 for nasopharyngeal carcinoma cells of NOX4 overexpression,compared with the NOX4 group, the proliferation ability of nasopharyngeal carcinoma cells in the NOX4+LY294002 group was reduced (72 h absorbance (A) value: 1.32 vs. 0.77), while the apoptotic rate was increased (1.1% vs. 3.1%).Treatment with radiotherapy, compared with the siNC/Vector group, the proliferation ability of nasopharyngeal carcinoma cells in the siNOX4 group was reduced (72 h absorbance (A) value: 0.72 vs. 0.33), and the apoptotic rate was increased (7.8% vs. 17.3%). However, in the NOX4 group, the proliferation of nasopharyngeal carcinoma cells was enhanced (72 h absorbance (A) value:0.65 vs. 0.78), and the apoptotic rate was reduced (8.1% vs. 3.8%). Compared with the NOX4+radiation group, the proliferation ability of nasopharyngeal carcinoma cells in the NOX4+radiation+LY294002 group was reduced (72 h absorbance (A) value: 0.79 vs. 0.56), while the apoptotic rate was increased (3.8% vs. 8.1%). Conclusion: NOX4 can inhibit radiosensitivity of nasopharyngeal carcinoma cells possibly by activating PI3K/AKT pathway.