Abstract: Objective    To investigate the mechanism of celecoxib, a COX-2 inhibitor, in inducing cell apoptosis in human laryngocarcinoma Hep-2 cells. Methods    MTT was used to observe the proliferation of Hep-2 cells treated with various doses of celecoxib. Cell apoptosis was determined by flow cytometry and morphologic observation under fluorescent microscopy with Hoechst33258 staining. Protein expressions of Bax, Bcl-2， COX-2 were examined  by western blot. Caspase-3 activation was examined  by western blot. Results    MTT results showed that celecoxib could inhibit the proliferation of Hep-2 cells in a time- and concentration- dependent manner. Hoechst33342 fluorescent staining showed the nucleus gradually appeared agglutination and  fragmentation after the treatment of celecoxib. Apoptosis rate in the groups treated with 70 and 100μ mol/L celecoxib  were (28.9±2.74)% and (32.7±3.96)% correspondingly. Wwestern blot showed that celecoxib could down-regulate the levels of expressions of COX-2 and Bcl-2 protein, up-regulate Bax protein’s expression, and activate caspase-3. Conclusion    Celecoxib  can effectively inhibit the proliferation of Hep-2 cells and induce the apoptosis of Hep-2 cells. The induction of apoptosis may be related to the increased Bax/Bcl-2 ratio  and activation of  caspase-3.

Key words: Hep-2 cell, Cyclooxygenase-2, Apoptosis, Celecoxib