Objective To investigate the influence of celecoxib, cycloxygenase-2（COX-2） selective inhibitor, upon the proliferation of KB/VCR cells, and analyze the effect of celecoxib on the expression of P-glycoprotein（P-gp）.Methods MTT method was employed to study the inhibitory effect of celecoxib on KB/VCR cells, which were divided into vincristine（VCR） group, Celecoxib group, Celecoxib+VCR group, Celecoxib+VCR+prostaglandin E2 （ PGE2） group. Western blot was employed to detect the expression of P-gp, Bcl-2 and Bcl-XL. Flow cytometry was used to evaluate the apoptosis of KB/VCR cells. All of the data were statistically analyzed using SPSS 13.0 software package.Results The growth inhibition rate of KB/VCR cells in Celecoxib+VCR group was significantly higher than that in Celecoxib group, VCR group and Celecoxib+VCR+PGE2 group（PConclusionCelecoxib could enhance the toxicity of VCR against KB/VCR cells. The mechanism probably correlates with the downregulation of celecoxib on the expression of P-gp and the increase of apoptosis.
