Circular RNA circ_0002984 Facilitates the Proliferation and Migration of Ox-LDL-Induced Vascular Smooth Muscle Cells via the Let-7a-5p/KLF5 Pathway.

Circular RNAs (circRNAs) play an important role in the progression of atherosclerosis (AS). This study aimed to explore the exact role and mechanism of circ_0002984 in oxidized low-density lipoprotein (ox-LDL)-mediated human vascular smooth muscle cells (HVSMCs). The model of smooth muscle cell phenotype switching was constructed by treating HVSMCs with ox-LDL. The levels of circ_0002984, let-7a-5p, and kruppel-like factor 5 (KLF5) were measured by quantitative real-time PCR or western blot assay. Cell proliferation, migration, and apoptosis were detected by Cell Counting Kit-8 (CCK-8), EdU staining, wound healing assay, transwell assay, and flow cytometry. The expression of cleaved-caspase-3 and KLF5 was examined by western blot. The relationship between let-7a-5p and circ_0002984 or KLF5 was verified by dual-luciferase reporter assay or RIP assay. The results showed that circ_0002984 and KLF5 were up-regulated, while let-7a-5p was down-regulated in AS patients and ox-LDL-disposed HVSMCs. Silence of circ_0002984 suppressed proliferation and migration, and promoted apoptosis in ox-LDL-stimulated HVSMCs. Moreover, circ_0002984 sponged let-7a-5p to regulate the proliferation, migration, and apoptosis in ox-LDL-resulted HVSMCs. In addition, KLF5 was a target of let-7a-5p and its overexpression reversed the effect of let-7a-5p on the proliferation, migration, and apoptosis in ox-LDL-treated HVSMCs. Also, circ_0002984 positively regulated KLF5 expression by absorbing let-7a-5p. The promotion effect of circ_0002984 on the proliferation and migration of ox-LDL-treated HVSMCs was reversed by KLF5 silencing. Taken together, depletion of circ_0002984 inhibited the proliferation and migration of ox-LDL-stimulated HVSMCs, which might be achieved by modulating the let-7a-5p/KLF5 axis.