Blocking circ_UBR4 suppressed proliferation, migration, and cell cycle progression of human vascular smooth muscle cells in atherosclerosis.

The circ_UBR4 (hsa_circ_0010283) is a novel abnormally overexpressed circRNA in oxidized low-density lipoprotein (ox-LDL)-induced model of atherosclerosis (AS) in human vascular smooth muscle cells (VSMCs). However, its role in the dysfunction of VSMCs remains to be further investigated. Here, we attempted to explore its role in ox-LDL-induced excessive proliferation and migration in VSMCs by regulating Rho/Rho-associated coiled-coil containing kinase 1 (ROCK1), a therapeutic target of AS. Expression of circ_UBR4 and ROCK1 was upregulated, whereas miR-107 was downregulated in human AS serum and ox-LDL-induced VSMCs. Depletion of circ_UBR4 arrested cell cycle, suppressed cell viability, colony-forming ability, and migration ability, and depressed expression of proliferating cell nuclear antigen and matrix metalloproteinase 2 in VSMCs in spite of the opposite effects of ox-LDL. Notably, ROCK1 upregulation mediated by plasmid transfection or miR-107 deletion could counteract the suppressive role of circ_UBR4 knockdown in ox-LDL-induced VSMCs proliferation, migration, and cell cycle progression. In mechanism, miR-107 was identified as a target of circ_UBR4 to mediate the regulatory effect of circ_UBR4 on ROCK1. circ_UBR4 might be a contributor in human AS partially by regulating VSMCs' cell proliferation, migration, and cell cycle progression via circ_UBR4/miR-107/ROCK1 pathway.