Simvastatin Inhibits Epithelial-to-Mesenchymal Transition Through Induction of HO-1 in Cultured Renal Proximal Tubule Cells

Studies have shown that simvastatin (SIM) inhibits epithelial-mesenchymal transition (EMT), a key step in fibrosis, and activates the anti-fibrotic heme oxygenase-1 (HO-1) gene in renal proximal tubule cells independent of its lipid-lowering. We tested the hypothesis that SIM inhibits EMT via HO-1-dependent suppression of reactive oxygen species (ROS) release. Renal proximal tubule cells were treated with either 10 μM SIM or 10 ng/ml transforming growth factor-β1 (TGFβ1) or with their combination and promoter activity of the alpha-smooth muscle actin (α-SMA) gene, stress fiber formation (markers of EMT), as well as ROS production were determined. HO-1 was manipulated via genetic and pharmacologic means. SIM prevented TGFβ1-dependent EMT and ROS production. Inhibition/knockdown of HO-1 reversed, while induction/overexpression of HO-1 emulated beneficial effects of SIM. SIM, via HO-1, suppresses TGFβ1-dependent ROS production and, hence, EMT. Further evaluation of the anti-fibrotic nature of SIM in the kidney would be useful in the treatment of chronic kidney disease.