Effect of rosiglitazone on the expression of CTGF induced by TGF-β1 in HK-2 cell line

Objective To investigate the effect of rosiglitazone on the expression of CTGF in cultured human proximal tubular epithelial cell line HK-2 induced by TGF-β1. Methods The protein expression was examined by Western blot. The mRNA expression was tested by RT-PCR. Results The low levels of CTGF mRNA and protein expression were observed in HK-2 cell line and up-regulated by TGF-β1 in dose- and time-dependent manner. Rosiglitazone significantly inhibited enhanced CTGF mRNA and protein expression in HK-2 cell line stimulated by TGF-β1 (4 ng/ml) in a dose-dependent manner. The CTGF mRNA decreased by 17.5%, 41.5% and 61.2%(P0.01) in rosiglitazone concentrations of 1, 5 and 10 μmol/L respectively. The CTGF protein decreased by 19.9% and 52.3%(P0.01) in rosiglitazone concentrations of 5 and 10 μmol/L respectively. The specific PPARγ antagonist GW9662 (1 μmol/L) abrogated the inhibition of rosiglitazone on CTGF expression. PPARγ natural ligand 15d-PGJ2 significantly inhibited CTGF mRNA and protein expression induced by TGF-β1 (4 ng/ml) in a dose-dependent manner. GW9662 (1 μmol/L) abrogated the inhibition of CTGF expression by rosiglitazone. Fibronectin protein expression stimulated by TGF-β1 (4 ng/ml) decreased by 39.9% and 53.4%(P0.01) in the rosiglitazone concentrations of 5 and 10 μmol/L respectively. Conclusion Rosiglitazone inhibits CTGF and FN expression induced by TGF-β1 in HK-2 cell line mediated by activating PPARγ