CircMED12L Protects Against Hydrogen Peroxide-induced Apoptotic and Oxidative Injury in Human Lens Epithelial Cells by miR-34a-5p/ALCAM axis.

PURPOSE

Cataract is the leading cause of visual impairment and reversible blindness. Despite advances in surgical removal of cataracts, cataract continues to be a leading public-health issue due to the complications after surgery. Circular RNAs (circRNAs) have been showed to be implicated in the pathophysiology of age-related cataract (ARC). Herein, this work elucidated the role and mechanism of circMED12L in the process of ARC.

METHODS

Human lens epithelial cells (HLECs) were exposed to hydrogen peroxide (HO) in experimental groups. Levels of genes and proteins were measured by qRT-PCR and western blotting. Cell growth was evaluated by Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. The oxidative stress was assessed by detecting the activity of malondialdehyde, catalase, and superoxide dismutase. The interaction between miR-34a-5p and circMED12L or ALCAM (activated leukocyte cell adhesion molecule) was validated using dual-luciferase reporter and RNA immunoprecipitation assays.

RESULTS

CircMED12L expression was lower in the lens epithelium of ARC patients and HO-induced HLECs compared with the normal individuals and untreated cells. Functionally, forced expression of circMED12L could alleviate HO-induced viability inhibition, as well as apoptotic and oxidative injury in HLECs. Mechanistically, circMED12L/miR-34a-5p/ALCAM constituted a feedback loop in HLECs. MiR-34a-5p was increased, while ALCAM was decreased in ARC patients and HO-induced HLECs. High expression of miR-34a-5p reversed the protective effects of circMED12L on HLECs under HO treatment. Besides, inhibition of miR-34a-5p could repress HO-induced apoptotic and oxidative injury in HLECs, which were abolished by subsequent ALCAM knockdown.

CONCLUSION

Overexpression of circMED12L could protect against HO-induced apoptosis and oxidative stress in HLECs by miR-34a-5p/ALCAM axis.