Chronic renal failure (CRF) mainly results from kidney fibrosis. Epithelial-to-mesenchymal transition (EMT) occurs in stressed tubular epithelial cells and contributes to renal fibrosis. Transforming growth factor-β1 (TGF-β1) has been shown to initiate and complete the whole EMT process. Peroxisome proliferators-activated receptor-γ (PPAR-γ) exerts anti-inflammatory, anti-fibrotic and vaculo-protective effects on different renal diseases. Telmisartan is a member of angiotensin II (Ang II) receptor blocker (ARB) family. Recent studies show that Telmisartan has a partial agonistic effect on PPAR-γ. Therefore, we tested the hypothesis that Telmisartan reverses the progression of induced EMT by TGF-β1 in cultured human renal proximal tubular epithelial (HK-2) cells. Cultured HK-2 cells were treated with TGF-β1 (3 ng/ml), a combination of TGF-β1 and Telmisartan (10-200 umol/L) and a combination of TGF-β1, Telmisartan and GW9662, a PPAR-γ antagonist for 48 hours. EMT was determined by quantitative real-time PCR analysis of E-cadherin (E-cad), Connective Tissue Growth Factor (CTGF) and PPAR-γ transcript expression and immunocytochemical analysis of E-cad, α-Smooth Muscle Actin (α-SMA) and PPAR-γ protein expression. TGF-β1 induced phenotypic EMT in cultured HK-2 cell line via significantly reduced E-cad expression and significantly increased CTGF, α-SMA expression in association with the loss of epithelial morphology. Telmisartan reversed all EMT markers in a dose-dependent manner which was inhibited by PPAR antagonist GW9662. In the present study, it was suggested that Telmisartan attenuated TGF-β1 induced EMT by agonistic activation of PPAR-γ.
Keywords: GW9662; PPAR-γ; TGF-β1; epithelial-to-mesenchymal transition; proximal tubular epithelial cells; telmisartan.