Slit2 Promotes Angiogenic Activity Via the Robo1-VEGFR2-ERK1/2 Pathway in Both In Vivo and In Vitro Studies

PURPOSE. Recent research has provided novel but contrary insight into the function of Slit2-Robo signaling in angiogenesis. Although the role of Robo in choroidal neovascularization (CNV) has been studied, the effect of its ligand, Slit2, on CNV development is unclear. This study investigated the role of endogenous Slit2 in CNV and the possible mechanisms. METHODS. Laser-induced CNV in Slit2 transgenic and wild-type mice was used to study the effects of endogenous Slit2 on angiogenesis in vivo. Fluorescein angiography was performed to evaluate the leakage area of each lesion. Plasmid-based gene transfer technology was used to increase Slit2 expression and to study its effects on human umbilical vein endothelial cells (HUVECs) in vitro. Cell proliferation, migration, and tube formation were assessed. Quantitative real-time PCR and Western blot were used to measure expression in the extracellular signal-related kinase 1/2 (ERK1/2), protein kinase B (AKT), and p38 mitogen-activated protein kinase (p38 MAPK) molecular pathways. RESULTS. Laser treatment led to more CNV and vascular leakage in Slit2 transgenic mice compared with wild-type mice. Upregulation of Slit2, Robo1, VEGF receptor 2 (VEGFR2), and phosphorylated ERK1/2 (p-ERK1/2) were detected in retina and choroidal tissue of laser-treated transgenic mice. After transfection of HUVECs with a Slit2 overexpression plasmid, cell proliferation, migration, and tube formation capacities were promoted. Slit2, Robo1, VEGFR2, and p-ERK1/2 were elevated in transfected HUVECs. CONCLUSION. Slit2 overexpression promoted angiogenic effects in both a laser-induced CNV mouse model and HUVECs and promoted the biological activity of endothelial cells. Slit2 may promote angiogenesis by upregulating Robo1 and activating the VEGFR2-ERK1/2 pathway.