Reactive oxygen intermediates increase vascular endothelial growth factor expression in vitro and in vivo.

Abstract

Elevated vascular endothelial growth factor (VEGF) levels are required for ocular and tumor angiogenesis in animal models. Ischemic hypoxia is strongly correlated with increased VEGF expression in these systems and is considered a physiologically relevant stimulus. Because ischemic hypoxia is often followed by reperfusion and reactive oxygen intermediate (ROI) generation, we examined the potential role of ROI in the control of VEGF gene expression. Human retinal pigment epithelial cells exposed to superoxide or hydrogen peroxide rapidly increased VEGF mRNA levels. Superoxide-associated mRNA increases were dose dependent, blocked by antioxidants, and associated with elevated VEGF protein levels in conditioned media. Increases in VEGF mRNA levels were also observed in cultured human melanoma and rat glioblastoma cells with superoxide or hydrogen peroxide. Cycloheximide prevented the ROIassociated increases in VEGF mRNA. Transcriptional inhibition with actinomycin D revealed an inducible increase in VEGF mRNA half-life, but nuclear run-on experiments showed no increase in VEGF transcriptional rate. Reoxygenation of human retinal pigment epithelial cells in vitro and ocular reperfusion in vivo increased retinal VEGF mRNA levels. Antioxidants prevented the reperfusion-associated VEGF mRNA increases in retina. We conclude that ROIs increase VEGF gene expression in vitro and during the reperfusion of ischemic retina in vivo. The ROI-associated increases are mediated largely through increases in VEGF mRNA stability. ( J. Clin. Invest. 1996 . 98:1667 -1675 ).

Vascular dysfunction induced by elevated glucose levels in rats is mediated by vascular endothelial growth factor.

“…The plausibility of this scenario is supported by several lines of evidence: (a) reductive stress increases superoxide production by several mechanisms (12) including inhibition of xanthine dehydrogenase as discussed above; (b) reactive oxygen intermediates increase VEGF mRNA expression (44); (c) superoxide dismutase and VEGF antibodies prevent vascular dysfunction induced by elevated glucose and sorbitol levels in the skin chamber granulation tissue (Figs. 2, 3, and 5); and (d) neutralizing VEGF antibody prevents vascular dysfunction induced by reactive oxygen intermediates (Fig.…”

Vascular endothelial growth factor in eye disease

“…Increased levels of oxidative stress have been linked to increased production of VEGF upon high glucose treatment in vitro and in the diabetic retina (El-Remessy, 2003b;Ellis et al, 1998;Ellis et al, 2000;Kuroki et al, 1996;Obrosova et al, 2001). The mechanisms by which oxidative stress contributes to VEGF overexpression are not fully understood.…”

Novel chimeric gene promoters responsive to hypoxia and ionizing radiation

“…33 Differentiated C 2 C 12 myoblasts and endothelial cells exposed to ROS-producing agents exhibited a concentration-dependent increase in VEGF production in vitro and in vivo. [38][39][40] Moreover, the flavoprotein diphenylene iodonium, which blocks ROS generation by NAD(P) oxidase, abolishes the hypoxic induction of HIF1-regulated genes. 41 In contrast, H 2 O 2 inhibited HIF1 binding and Epo induction under hypoxia.…”