Circular RNA circZNF292 regulates H2O2-induced injury in human lens epithelial HLE-B3 cells depending on the regulation of the miR-222-3p/E2F3 axis

Circular RNAs (circRNAs) play important roles in the pathogenesis of age-related cataract (ARC). CircRNA zinc finger protein 292 (circZNF292, hsa_circ_0004058) is downregulated in ARC lens capsules. Here, we focused on its precise roles in oxidative stress underlying the pathogenesis of ARC. CircZNF292, microRNA (miR)-222-3p, and E2F transcription factor 3 (E2F3) were quantified by quantitative real-time polymerase chain reaction or western blot. Cell viability was assessed by the cell counting kit-8 assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The activities of superoxide dismutase, catalase, and malondialdehyde were measured using the corresponding assay kit. Targeted correlations among circZNF292, miR-222-3p, and E2F3 were verified by the dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. Our data showed that circZNF292 was downregulated in ARC tissues and H2O2-treated human lens epithelial B3 (HLE-B3) cells. Increased expression of circZNF292 alleviated H2O2-induced cell viability suppression, apoptosis promotion, and oxidative stress enhancement. Mechanistically, circZNF292 directly targeted miR-222-3p, and circZNF292 regulated E2F3 expression through miR-222-3p. MiR-222-3p was a functional mediator of circZNF292 in modulating H2O2-induced injury in HLE-B3 cells. Furthermore, reduced level of miR-222-3p ameliorated H2O2-induced HLE-B3 cell damage by upregulating E2F3. Our present study demonstrated that increased expression of circZNF292 ameliorated H2O2-induced injury in HLE-B3 cells at least in part through the miR-222-3p/E2F3 axis, highlighting a novel insight into the involvement of circRNAs in the pathogenesis of ARC.