[Inhibition of micro RNA-9 expression promotes UV-induced ROS damage in nasopharyngeal carcinoma cells].

OBJECTIVE: To investigate the effects of down-regulated miR-9 expression on ultraviolet rays (UV)-induced reactive oxygen species (ROS) damage in nasopharyngeal carcinoma (NPC) cells. METHODS: The NPC cells were transfected with inhibitors of miR-9 by lipofectamine to decrease the expression of miR-9, and the cells transfected with inhibitor control as the control. ROS levels following UV exposure were examined with DCF-DA method and the concentration of glutathione was analyzed via the benzoic acid method; DNA damage and apoptosis also were evaluated. RESULTS: There was significant difference in ROS levels between miR-9 expression-inhibited cells and control cells (26 895 +/- 218 vs 15 765 +/- 927, t = 39.754, P < 0.001), and also there were significant differences in DNA damage rates (28.0% +/- 10.0% vs 23.6% +/- 9.2%) and in apoptosis rates (8.0% +/- 0.9% vs 4.5% +/- 0.8%) following UV exposure between two groups of cells. The miR-9 expression-inhibited cells showed lower level (1.87 +/- 0.15) micromol/L of glutathione compared with the control cells (9.85 +/- 0.15) micromol/L (t = -48.832, P < 0.001). CONCLUSION: Inhibition of miR-9 expression promoted UV-induced ROS damage in nasopharyngeal carcinoma cells.