Inhibition of retinal neovascularization via MB660 mediated HIF-1α degradation

Abstract

Purpose: Anti-cancer, anti-viral, anti-bacterial, and anti-inflammatory effect of MB660 (3,4-dihydro-2,2-dimethyl-2H-naphtho-[1,2-b]pyran-5,6-dione) has been well known. We aimed to demonstrate the anti-angiogenic effect of MB660 on the retinal neovascularization via HIF-1α degradation. Methods: The toxicity of MB660 was evaluated by modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay in human retinal microvascular endothelial cells (HRMECs) as well as histologic examination and terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling staining in the MB660-injected retina of C57BL/6J mice. Retinal neovascularization was examined by fluorescence angiography and vessel counting in cross sections after intravitreal injection of MB660 in the oxygen induced retinopathy (OIR) mouse model. Western blot analysis was used to assess inhibition of hypoxia inducible factor (HIF)-1α by MB660 at a protein level under hypoxic condition induced by CoCl2. Results: MB660 did not show any toxicity on HRMECs and did not induce any structural or inflammatory changes in normal retina layers up to 1 µM. Intravitreal injection of MB660 effectively reduced anomalous retinal angiogenesis, shown as decreased neovascular tufts on fluorescein angiography and decreased vascular lumens in cross section in the OIR mouse model and also attenuated CoCl2 induced HIF-1α production. Conclusions: Our data suggest that MB660 may have anti-angiogenic activity on retinal neovascularization by suppressing hypoxia-induced vascular endothelial growth factor expression via attenuating HIF-1α without retinal toxicity.