Circ-C16orf62 Regulates Oxidized low-density Lipoprotein-induced Apoptosis, Inflammation, Oxidative Stress and Cholesterol Accumulation of Macrophages via Mediating RAB22A Expression by Targeting miR-377

Atherosclerosis (AS) is one of the most common and important vascular diseases. It is believed that the abnormal expression of circular RNAs (circRNAs) plays an important role in AS. Hence, we investigate the function and mechanism of circ-C16orf62 in AS development. In this study, oxidized low-density lipoprotein (ox-LDL)-treated human macrophages (THP-1) were used as pathological conditions of AS in vitro. The expression of circ-C16orf62, miR-377 and Ras-related protein (RAB22A) mRNA was detected by real-time quantitative polymerase chain reaction (RT-qPCR) or western blot. Cell viability or cell apoptosis was assessed by cell counting kit-8 (CCK-8) assay or flow cytometry assay. The releases of proinflammatory factors were investigated using enzyme-linked immunosorbent assay (ELISA). The production of malondialdehyde (MDA) and superoxide dismutase (SOD) was examined to assess oxidative stress. Total cholesterol (T-CHO) level was detected, and cholesterol efflux level was tested using a liquid scintillation counter. The putative relationship between miR-377 and circ-C16orf62 or RAB22A was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.circ- C16orf62 expression was elevated in AS serum samples and ox-LDL-treated THP-1 cells. Apoptosis, inflammation, oxidative stress and cholesterol accumulation induced by ox-LDL were suppressed by circ-C16orf62 knockdown. Circ-C16orf62 could bind to miR-377 and thus increased the expression level of RAB22A. Rescued experiments showed that circ-C16orf62 knockdown alleviated ox-LDL-induced THP-1 cell injuries by increasing miR-377 expression, and miR-377 overexpression lessened ox-LDL-induced THP-1 cell injuries by degrading RAB22A level. In conclusion, circ-C16orf62 played a crucial role in the regulation of apoptosis, inflammation, oxidative stress and cholesterol accumulation in ox-LDL-treated human macrophages via mediating the miR-377/RAB22A axis, hinting that circ-C16orf62 might be involved in AS progression.