CircUsp9x/miR-599/stim1 axis regulates proliferation and migration in vascular smooth muscle cells induced by oxidized-low density lipoprotein.

Circular RNAs (circRNAs) regulate the function of vascular smooth muscle cells (VSMCs) in atherosclerosis (AS) progression. We aimed to explore the role of circUSP9X in oxidized low-density lipoprotein (ox-LDL)-induced VSMCs. Cell proliferation was assessed using cell counting kit-8 and EDU assays. Cell migration was evaluated using Transwell and wound healing assays. The interaction between circUSP9X or STIM1 and miR-599 was analyzed using dual-luciferase reporter and RNA pull-down assays. Their levels were examined using quantitative real-time PCR. CircUSP9X and STIM1 expression was increased, whereas miR-599 expression was reduced in the serum of patients with AS and ox-LDL-stimulated VSMCs. Overexpression of circUSP9X facilitated the proliferation and migration of VSMCs induced by ox-LDL. CircUSP9X sponged miR-599, which targeted STIM1. MiR-599 reversed the effects induced by circUSP9X, and STIM1 reversed the effects induced by miR-599. Taken together, CircUSP9X promoted proliferation and migration in ox-LDL-treated VSMCs via the miR-599/STIM1 axis, providing a theoretical basis for the role of circUSP9X/miR-599/STIM1 axis in AS.