Novel NADPH oxidase inhibitor VAS2870 suppresses TGF-[beta]-dependent epithelial-to-mesenchymal transition in retinal pigment epithelial cells

NADPH oxidases (NOXs) are important in the pathophysiology of fibrotic diseases. The expression and activity of NOXs are regulated by growth factors, including transforming growth factor (TGF-[beta]). The proliferation of retinal pigment epithelial (RPE) cells following epithelial- to-mesenchymal transition (EMT) is a major pathological change involved in proliferative vitreoretinopathy (PVR). The aim of the present study was to determine the effects of the novel NOX inhibitor VAS2870 on the TGF-[beta]-dependent expression of NOX4 and associated cellular events in RPE cells. Cell viability was examined using a Cell Counting Kit-8 assay and cell cycle progression was detected by flow cytometric analysis. Immunofluorescence analysis and western blot analysis were performed to assess EMT. It was found that TGF-[beta] increased the expression of NOX4 and that pre-incubation with VAS2870 eliminated this effect. Additionally, TGF-[beta] promoted RPE migration and increased EMT. Pre-incubation with VAS2870 significantly prevented TGF-[beta]2-induced EMT by decreasing the levels of [alpha]-smooth muscle actin and E-cadherin, and also inhibited the migratory ability of the RPE cells, as demonstrated by scratch assays. Finally, VAS2870 suppressed the proliferation of RPE cells, and led to [G.sub.1]-phase cell cycle arrest and a significant downregulation of the expression of cyclin D1. In conclusion, the pharmacological inhibition of NOX may be a promising tool for the treatment of PVR. Key words: VAS2870, NADPH oxidase 4, proliferation, epithelial-to-mesenchymal transition, retinal pigment epithelial cells, proliferative vitreoretinopathy, [alpha]-smooth muscle actin, cyclin D1, E-cadherin