Expression of glucocorticoid receptor in HaCaT cells under dexamethasone treatment or after withdrawal

Objective To investigate the expression of glucocorticoid receptor ( GR) α and β in cultured human keratinocytes ( HaCaT cells) with treatment of dexamethasone ( Dex) and after withdrawal. Methods The mRNA and protein expressions of GRα and GRβ in HaCaT cells after the treatment of Dex ( 10 -6mol/L) for 24 and 48 h and in 24,48 and 72 h after withdrawal of Dex were detected by real-time PCR and Western blot analysis respectively. The intracellular distribution of GRα and β was examined by immunofluorescence. Results In 24 or 48 h after Dex treatment,the expressions of GRα at mRNA and protein levels were reduced in a time-dependent manner ( P 0. 05) ,and those of GRβ were increased ( P 0. 05) as shown by real-time PCR and Western blot analysis. However,in 24,48 and 72 h after withdrawal of Dex,the above changes gradually recovered to their previous levels. Conclusion Dex down-regulates GRα but up-regulates GRβ,which may partly explain that the tachyphylaxisis correlated to persistent application of topical glucocorticoids. After Dex is removed,both GRα and GRβ could recover to their previous levels,suggesting long-term application of topical glucocorticoid should be avoided.