Physcion 8-O-β-glucopyranoside exerts protective roles in high glucose-induced diabetic retinopathy via regulating lncRNA NORAD/miR-125/STAT3 signalling.

Diabetic retinopathy (DR) is the leading cause of decreased vision and blindness globally. The aim of this study was to understand the role of physcion 8-O-β-glucopyranoside (PG) in high glucose (HG)-induced DR and to investigate whether lncRNA NORAD/miR-125/STAT3 signalling was the underlying mechanism involved in DR. To this end, the serum levels of NORAD, miR-125, and STAT3 were determined in patients with DR. The APRE-19 cells were subjected to HG treatment to construct the cell model of DR. HG-disposed APRE-19 cell injury was assessed by detecting cell viability, apoptosis, concentrations of pro-inflammatory cytokines including TNF-α and IL-1β, and ROS generation. Moreover, the effect of PG on HG-disposed APRE-19 cell injury was investigated. NORAD was then overexpressed to investigate the combined effects of NORAD overexpression and PG on HG-disposed APRE-19 cell injury. Furthermore, the regulatory relationship between NORAD and miR-125 as well as miR-125 and STAT3 was investigated. The expression levels of NORAD and STAT3 were significantly increased in the serum of DR patients, while the miR-125 expression was decreased. The HG treatment-induced injury to APRE-19 cells, which were alleviated by PG treatment. Moreover, PG alleviated HG-disposed injury to ARPE-19 cells by decreasing NORAD. NORAD negatively regulated miR-125 expression and the combined effects of NORAD and PG on HG-disposed ARPE-19 cell injury were reversed by miR-125 overexpression. Furthermore, STAT3 was confirmed as a target gene of miR-125. Our results show that PG exerts protective roles in HG-disposed DR via regulating lncRNA NORAD/miR-125/STAT3 signalling. NORAD/miR-125/STAT3 axis may provide a novel perspective for target therapy of DR.