The vast majority of diseases that cause catastrophic loss of vision do so as a result of abnormal angiogenesis and associated retinal edema, hemorrhage and gliosis. Current anti-angiogenic strategies used in the clinics to treat complications of neovascularization in diseases like macular degeneration and diabetic retinopathy target vascular endothelial growth factor (VEGF) or its receptors. However, potential problems with anti-VEGF therapy limits its utility; the need for repeated injections, potential secondary effects on other, non-endothelial, cell types and the involvement of non-VEGF angiogenic mechanisms may limit or attenuate patient responses. Combination therapy, targeting multiple pathways with multiple drugs, may achieve synergistic angiostatic activity that can circumvent these problems but this approach is limited by the absence of FDA-approved clinical drugs that target angiogenesis either upstream or downstream of VEGF. We propose modulating pathways critical to pathological angiogenesis by targeting micro RNAs (miRs); miRs generally function to silence expression of target genes by binding to specific sites on their 3' untranslated region (UTR) and recruiting a silencing complex that blocks translation. We have identified miR-132 as a microRNA which is not expressed in normal blood vessels, but which is up-regulated in angiogenic tissues and in endothelial cells stimulated with growth factors. Expression of miR-132 is sufficient to drive vascular sprouting and proliferation, whereas inhibition of miR-132 with a complementary anti-miR-132 blocks these responses. Thus, we have identified miR-132 as activating endothelial ceils to promote angiogenesis and an anti-miR that neutralizes miR-132, thereby suppressing retinal neovascularization without affecting normal vessels. We have shown that the molecular target of miR-132, p120RasGAP, is a potent negative regulator of Ras in resting vessels. Thus, p120RasGAP is targeted and suppressed by the pro-angiogenic miR-132. In this proposal, we will explore the potential utility of anti-miR-132 and other anti-mlRs delivered to the eye using a novel nanoparticle delivery platform, as a potent and sustained anti-angiogenic strategy for therapy of neovascular eye diseases.
Abnormal growth/function of blood vessels is a major contributing factor for several human ocular diseases including diabetic retinopathy and age related macular degeneration. This proposal seeks to understand how small RNA molecules termed microRNAs regulate this process and will evaluate the therapeutic potential of these molecules using several well-characterized animal models of human eye disease.
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