Roles Of Chloride Channels In Apoptotic Volume Decrease And Apoptosis Induced By 5-Fluorouacil In Nasopharyngeal Carcinoma Cells

Objective:1) To investigate the effect of 5-Fluorouacil (5-Fu) on cell apoptosis in nasopharyngeal carcinoma cells (CNE-2Z); 2) To clarify the activation of chloride channel induced by 5-Fu in CNE-2Z cells; 3) To study the roles of chloride channels in apoptotic volume decrease and apoptosis induced by 5-Fu in nasopharyngeal carcinoma cells.Methods:1) Apoptosis was monitored by Hoechst and flow cytometry; 2) Image analysis techniques were employed in this study. The Scion Image processor and analysis software were used to detect the diameter and area of CNE-2Z cells. The standardized volume, AVD and the effects of chloride channel blockers on AVD were calculated.3) The whole-cell patch clamp technique was used to record 5-Fu-activated chloride currents.Results:1.5-Fu induced significantly apoptosis in CNE-2Z cells. The apoptotic rate was (49.2±3.2)% in the cells treated with 5-Fu (100μmol/L). The chloride channel blocker NPPB (100μmol/L) decreased the apoptotic rate induced by 5-Fu to (12.5±2.6)%.2.5-Fu induced apoptotic cell volume decrease (AVD) in CNE-2Z cells, When challenged with 100μmol/L 5-Fu, cell volume decreased gradually and decreased approximately by 9%after 50 min, while cell volume only decreased by 1.5%after incubated with NPPB and 5-Fu in the same time, the result indicated that chloride channel blocker suppressed 5-Fu-induced apoptotic cell volume decrease.3.5-Fu activated a chloride current with characteristics similar to the volume-activated chloride current in CNE-2Z cells; The current was inhibited by extracellular application of chloride channel blocker (NPPB, tamoxifen) in all voltage steps applied.4. ClC-3 SiRNA inhibited ClC-3 channel expression and suppressed 5-Fu-activated chloride current in CNE-2Z cells. Conclusion:1.5-Fu activated chloride channels and induced cell shrinkage and cell apoptosis in CNE-2Z cells, chloride channel blocker suppressed 5-Fu-activated chloride channel and prevented appearance of 5-Fu-induced apoptotic cell volume decrease and apoptosis. These results indicated that chloride channels play an important role in apoptotic volume decrease and apoptosis induced by 5-Fu in CNE-2Z cells.2. ClC-3 chloride channel involve in 5-Fu-activated chloride current of the CNE-2Z cells.