IDENTIFICATION AND CHARACTERIZATION OF A NOVEL SYNTHETIC HOMOISOFLAVONOID AS AN INHIBITOR OF RETINAL ANGIOGENESIS.

Abstract

Purpose: Prevention of pathological angiogenesis in the eye is key to treatment of retinopathy of prematurity (ROP). The present therapies to treat this disease include laser therapy, cryotherapy, and anti-angiogenic biologics. However at present there are no small molecule drugs to treat this disease on the market. Hence there is a pressing need for developing novel specific inhibitors of pathological angiogenesis in the eye. Towards this end we pursued analogs of a natural-source homoisoflavanone, a known inhibitor of ocular neovascularization, to develop novel antiangiogenic molecules. Here we demonstrate that a novel synthetic homoisoflavonoid, SH-11037, has potent antiangiogenic activity in vitro and in vivo.

Methods: Nearly 75 homoisoflavonoids have been screened for anti-proliferative activity on human umbilical vein endothelial cells (HUVECs) and human retinal microvascular endothelial cells (HRMVECs) using the Alamar blue proliferation assay. Retinoblastoma Y79 and uveal melanoma 92-1 cells were used as control cell lines to detect non-specific ocular cytotoxic compounds. The antiproliferative activity of SH-11037 was further studied using EdU incorporation assays, tube formation and migration assays, and immunocytochemistry. The oxygen-induced retinopathy (OIR) mouse model of ROP was used to test the antiangiogenic activity of SH-11037 in vivo.

Results: Several homoisoflavonoids were active against endothelial cells with GI50 values ranging from 150 nM to 50 µM. Among them, SH-11037 stands out as very potent (GI50 = 150 nM) with 10 fold more selective activity against HRMVECs as compared to HUVECs without inducing apoptosis. SH-11037 has negligible growth inhibitory effects on Y79 and 92-1 cell lines, suggesting the compound is non-toxic to other cell types. In addition, SH-11037 blocks DNA synthesis and tube formation of HRMVECs. While the parent homoisoflavanone acts through inhibition of the NF-κB pathway, SH-11037 does not inhibit nuclear translocation of p65. Finally, preliminary experiments show SH-11037 dose dependently inhibited retinal neovascularization in the OIR mouse model.

Conclusions: The novel synthetic compound SH-11037 is a specific and potent antiangiogenic molecule that should serve as an interesting drug lead for developing a small-molecule treatment for ocular neovascular diseases such as ROP.

Keywords: 706 retinopathy of prematurity • 700 retinal neovascularization • 654 proliferation