Abstract
The present study aimed to investigate the expression of microRNA (miRNA)-23a in blood and tear samples from diabetic retinopathy (DR) patients. Blood and tear samples were obtained from 33 patients with proliferative DR. Additionally, a rat model of DR was established. Reverse transcription-quantitative PCR was used to determine vascular endothelial growth factor (VEGF) mRNA and miRNA-23a expression levels, while ELISA and western blot analysis were performed to determine protein expression levels. Bioinformatics analysis and dual luciferase reporter assay were used to predict and validate the interaction between miRNA-23a and VEGF and cell proliferative ability was assessed with the MTT assay. In comparison to control patients VEGF mRNA and protein expression levels were significantly elevated in the blood and tear samples from patients with DR, while the expression level of miRNA-23a was significantly reduced. In blood and retinal tissues from a rat model of DR, the mRNA and protein expression levels of VEGF were significantly increased, while the miRNA-23a expression level was significantly decreased relative to controls. Dual luciferase reporter assay showed that miRNA-23a bound to the 3'-untranslated region (UTR) of VEGF. Moreover, over-expression of miRNA-23a significantly reduced the expression level of VEGF and the proliferative activity of human retinal microvascular endothelial cells. The elevated VEGF expression in the blood and tears of patients with DR may be related to the reduced miRNA-23a expression. miRNA-23a may regulate microvascular growth at the retina via VEGF and contribute to DR progression.