Hypoxia induced physiological stress plays a central role in various neovascular diseases of the eye. Increased expression of hypoxia-inducible factor 1 alpha (HIF-1) and subsequent formation of HIF-1 dimers active at the vascular endothelial growth factor (VEGF)-promoter leads to expression of this potent angiogenic factor in the retina, including retinal pigment epithelial (RPE) cells. We have previously demonstrated that insulin-like growth factor 1 (IGF-1) stimulates VEGF and IGF binding protein-3 (IGFBP-3) secretion in RPE cells. In this study we have examined IGF-1-induced HIF-1 expression, VEGF and IGFBP-3 secretion, and the autocrine actions of VEGF and IGFBP-3 on these processes in the spontaneously transformed RPE cell line ARPE-19. Cells were treated with cobalt chloride, IGF-1, human recombinant IGFBP-3 (rhIGFBP-3), and human recombinant VEGF (rhVEGF). Immunoblot analysis revealed IGF-1 induced up-regulation of total HIF-1 protein while luciferase reporter assays of HIF-1 transcriptional activity demonstrated accumulation of HIF-1 correlated with the formation of functional HIF-1 heterodimers. Western and ligand blot analyses of RPE cell conditioned medium confirmed that IGF-1 stimulated VEGF and IGFBP-3 secretion. rhVEGF stimulated IGFBP-3 secretion in an IGF-1 and HIF-1-independent manner, while rhIGFBP-3 attenuated IGF-1 induced VEGF secretion. These findings demonstrate the multifaceted autocrine regulation of IGF-1 induced VEGF secretion by IGFBP-3 secreted in response to both IGF-1 and to a lesser extent, VEGF. These results provide evidence for HIF-1-dependent and -independent mechanisms by which IGF-1 regulates VEGF and IGFBP-3 secretion.