microRNA-218 Inhibits Oxygen-induced Retinal Neovascularization via Reducing the Expression of Roundabout 1

BACKGROUND The mechanisms of pathological retinal neovascularization (RNV) remain unknown. Several microRNAs were reported to be involved in the process of RNV. Oxygen-induced retinopathy (OIR) is a useful model to investigate RNV. Our present work explored the expression and the role of microRNA-128 (miR-218) in oxygen-induced RNV. METHODS OIR was used to establish RNV model. The expression level of miR-218 in the retina from OIR mice was assessed by quantitative real-time reverse transcriptase polymerase chain reaction. Fluorescein angiography was performed in retinae of OIR mice, and RNV was quantified by hematoxylin and eosin staining to evaluate the effect of pCDH-CMV-miR-218 intravitreal injection on RNV in OIR mice. Roundabout 1 (Robo1) expression was detected by Western blotting in mouse retinal vascular endothelial cells expressing a high or low level of miR-218 and retinal tissues from OIR mice. Cell migration was evaluated by scratch wound assay. RESULTS In OIR mice, the expression level of miR-218 was significantly down-regulated (P = 0.006). Retinal Robo1 expression was significantly increased at both mRNA and protein levels (P = 0.001, 0.008; respectively). miR-218 intravitreal injection inhibited retinal angiogenesis in OIR mice, and the restoration of miR-218 in retina led to down-regulation of Robo1. CONCLUSIONS Our experiments showed that restoration of miR-218 inhibited retinal angiogenesis via targeting Robo1. MiR-218 contributed to the inhibition of retinal angiogenesis and miR-218 might be a new therapeutic target for preventing RNV.