Circular RNA NXN (circNXN) promotes diabetic retinopathy by regulating the miR-338-3p/FGFR1 axis

Diabetic retinopathy (DR) is the leading manifestation of diabetic microangiopathy. However, effective biomarkers and therapies are lacking. Circular RNAs (circRNAs) have been implicated in various diseases including DR. However, the role of circRNAs in DR remains elusive. In the present study, circNXN was upregulated in high glucose (HG)-treated human retinal microvascular endothelial cells (hRMECs). circNXN knockdown inhibited the proliferation, migration, and angiogenesis of hRMECs and promoted apoptosis. In addition, circNXN acted as a sponge for miR-338-3p to facilitate the FGFR1 (fibroblast growth factor receptor 1) expression. Furthermore, rescue assays revealed that the reduced promoting effect on hRMECs induced by the knockdown of circNXN could be reversed by a miR-338-3p inhibitor in HG-treated hRMECs. Additionally, in a DR rat model, circNXN downregulation ameliorated retinal vasculature changes. Our findings reveal a new therapeutic strategy for DR that may provide a new approach to clinical DR therapy.