Objective：To investigate the effect of celecoxib, a selective cyclooxygenase-2 inhibitor, to down-regulate the expression of multidrug resistance (mdrl) gene in the gastric cancer cell BGC823.
Methods：BGC823 cells were treated with celecoxib in different concentrations (0,10μmol/L and 100μmol/L) respectively.Prostaglandin E2 (PGE2) was detected by ELISA. Twenty four hs and 48 hs later，the expression of mdrl mRNA were detected by RT-PCR. P-gp protein expression in BGC823 cells was detected by immunocytochemical technique after celecoxib treatment.
Results：Celecoxib inhibited the expression of PGE2 in a dose dependent manner(P＜0.05,P＜0.01).Same effective situation between the concentration was found on the P-gp expression during the treatment with celecoxib; while the expression of mdrl mRNA  was down regulated more effectively after 48 h treatment when compared to that in 24 hs treatment group(P＜0.01).
Conclusions：Celecoxib can inhibit the expression of mdrl/P-gp in a time and dose dependent manner, which is likely to be through inhibiting COX-2 activity.The results suggest that a selective COX-2 inhibitor may play a potential role in overcoming the chemotherapeutic resistance of gastric cancer cells.