Repression of microRNA-21 inhibits retinal vascular endothelial cell growth and angiogenesis via PTEN dependent-PI3K/Akt/VEGF signaling pathway in diabetic retinopathy

Diabetic retinopathy (DR) is a microvascular complication of diabetes and one of the most common causes of blindness in active stage. This study is performed to explore the effects of microRNA-21 (miR-21) on retinal vascular endothelial cell (RVEC) viability and angiogenesis in rats with DR via the phosphatidylinositiol 3-kinase/protein kinase B (PI3K/Akt)/vascular endothelial growth factor (VEGF) signaling pathway by binding to phosphatase and tensin homolog (PTEN). Sprague Dawley (SD) rats were used for establishment of DR models. Target relationship between miR-21 and PTEN was assessed by bioinformatics prediction in combination with dual-luciferase reporter gene assay. Identification of expression of miR-21, PTEN and PI3K/Akt/VEGF signaling pathway-related genes in the retinal tissues was then conducted. In order to assess the contributory role of miR-21 in DR, the RVECs were transfected with mimic or inhibitor of miR-21, or siRNA-PTEN, followed by the detection of expression of PTEN and PI3K/Akt/VEGF-related genes, as well as the measurement of cell viability, cell cycle and apoptosis. Increased expression of miR-21 and PI3K/Akt/VEGF related genes, along with a reduced expression of PTEN was observed in the retinal tissues of DR rats. PTEN was targeted and negatively regulated by miR-21, while the PI3K/Akt/VEGF signaling pathway was activated by miR-21. RVECs transfected with miR-21 inhibitor exhibited promoted viability and angiogenesis, and inhibited apoptosis. To conclude, our results indicated that miR-21 overexpression could potentially stimulate RVEC viability and angiogenesis in rats with DR through activation of the PI3K/Akt/VEGF signaling pathway via repressing PTEN expression, highlighting the potential of miR-21 as a target for DR treatment.