NADPH Oxidase-induced oxidative stress enhances VEGF synthesis under hyperglycemic condition in ARPE-19 cells.

The increased reactive oxygen species (ROS) caused by hyperglycemia (HG) is thought to be a key event in the pathogenesis of diabetic retinopathy. In diabetes, increased vascular endothelial growth factor (VEGF) expression is reported to increase ROS. Using a human RPE cell-line (ARPE-19), we investigated whether HG could promote the expression of VEGF independently of Angiotensin II through the prorenin receptor (PRR), via a NADPH oxidase (Nox)-dependent mechanism. HG significantly induced the expression of PRR, Nox2, Nox4, and VEGF. Also, PRR, Nox2/4, and Rac1 siRNAs, but not the control siRNA, significantly reduced the HG-induction of VEGF. Nox4 overexpression significantly potentiated PRR-induced stimulation of VEGF. Inhibitors of Nox significantly abolished HG-induction of VEGF. Both catalase and superoxide dismutase significantly attenuated VEGF induction by HG, indicative of the involvement of Nox-derived O2– and H2O2 signaling in regulation of VEGF regulation. In summary, Nox4-derived ROS signaling is implicated in the HG-induced increase of VEGF expression through PRR. Nox and redox signaling components can be considered as potential therapeutic targets for treatment of angiogenesis-dependent retinal diseases, including diabetic retinopathy.