Objective       To determine the effects of dexamethasone (Dex) on the expression of P-glycoprotein (P-gp) in human normal liver cell line L02 cells

and investigate the role of phosphatidylinositol 3 kinase (PI3K) /protein kinase B (Akt) pathway in the regulation of P-gp expression.       Methods      The levels of P-gp expression were detected among untreated

Dex alone treated

PI3K/Akt inhibitor LY294002 alone treated

and both Dex and LY294002 treated L02 cells using Western blot assay. The levels of Akt expression were also detected in untreated and Dex treated L02 cells by Western blotting. The relationship of the expression of P-gp with that of Akt in L02 cells was analyzed.       Results      The expression levels of P-gp and Akt were significantly increased by 60.8% and 25.0% in L02 cells after treated with 10 μmol/L Dex for 24 h compared with those in untreated L02 cells (P=0.026 7

0.035 8). The expression level of P-gp was positively correlated with the level of Akt in L02 cells (Pearson correlation coefficient=0.026 7

P0.01). The level of P-gp was remarkedly decreased by 33.8% in LY294002 treated L02 cells than in untreated L02 cells (P=0.018 4). The level of P-gp in Dex alone treated L02 cells accounted for (163.5±18.4)% of untreated cells

significantly higher than that of L02 cells treated by combination of Dex and LY294002 [(130.1±22.0)%

P=0.031 3].       Conclusion       Dex may increase the expression level of P-gp in L02 cells by activation of PI3K/Akt signaling.