Abstract: Abstract:Objective To investigate the effect of celecoxib, a selective COX-2 inhibitor, on the expression of multidrug resistance gene (MDR1) and P-glycoprotein (P-gp) in human tongue cancer drug-resistance cell line Tca8113/BLM. Methods Human tongue squamous cell carcinoma cell line Tca8113 cells were repeatedly treated with BLM (30μg/ml) to establish drug-resistant cell line Tca8113/BLM. The inhibitory effect of celecoxib on Tca8113/BLM cell line was determined by MTT assay. The expression of P-gp and MRP were detected by flow cytometry and RT-PCR, respectively. Results The MTT results suggested that celecoxib inhibited the growth and proliferation of Tca8113/BLM cell lines in dose-dependent manner. Celecoxib treatment also resulted in significant down-regulated expression of MDR1 mRNA and P-gp. Conclusion Celecoxib shows a significant effect on inhibiting expression of MDR1 mRNA and P-gp in Tca8113/BLM cells, this is probably related to enhancing the lethal effects of anticancer agents against carcinoma cells.