Purpose
Vascular endothelial growth factor (VEGF) is a well-established promoter and biomarker of pathological neovascularization in diabetic retinopathy (DR) and age-related macular degeneration (AMD). In the present study, we have developed a novel strategy of modulating VEGF-induced activation of the FAK/SRC-paxillin signalsome to prevent neovascular eye disease.
Methods
We designed compound JP-153 to target paxillin for selective modulation. Using human primary retinal endothelial cells (RECs) we measured proliferation with the tetrazolium salt, WST-1. We used a scratch wound and transwell migration assay plate to assess REC migration. Immunoblotting was carried out to identify FA signaling in RECs. We loaded JP-153 into a topical ophthalmic microemulsion for administration in the in vivo murine oxygen-induced retinopathy (OIR) model of proliferative retinopathy.
Results
VEGF enhanced REC proliferation and migration over 24 hours with significant activation of FA proteins paxillin and FAK within just 15 minutes. JP-153 (0.5 µM) prevented the activation of FA assembly sites: paxillin Y118 and FAK Y576/577 (P < 0.001) independent of ERK-1/2 (P>0.05), a regulator of FA disassembly. JP-153 inhibited proliferation and migration at concentrations ranging from 0.1 to 0.5 µM (P < 0.001). In the murine OIR model, JP-153 dose-dependently prevented neovascular tufting and increased avascular area (P < 0.001; n = 8-14 mice/group). Immunoblotting analysis of whole-retina homogenates revealed a dose-dependent reduction in total paxillin levels following JP-153 treatment (P < 0.05).
Conclusions
JP-153 afforded sub-micromolar potency to inhibit REC proliferation and migration, in vitro. Additionally, the topical administration of JP-153 was successful in delivering therapeutic doses of JP-153 to the retina. Together, our data highlight the essential and dynamic role of paxillin in regulating pathological RNV. In summary, we have discovered the first small-molecule modulator of paxillin signaling that is capable of disrupting VEGF-induced FAK/Src-paxillin activation, in vitro and in vivo. We thus postulate that paxillin is a potential viable target in treating neovascular disease, the leading cause of blindness in humans.