Circular RNA hsa_circ_0008896 accelerates atherosclerosis by promoting the proliferation, migration and invasion of vascular smooth muscle cells via hsa-miR-633/CDC20B (cell division cycle 20B) axis

Circular RNAs, a class of circularly closed non-coding RNAs, play essential roles in the formation of atherosclerosis, which is a frequent cause of cardiovascular and cerebrovascular diseases. Although many circular RNAs are found to be involved in the progression of atherosclerosis, more circular RNA regulators still need to be identified, to improve the understanding of the regulatory networks of atherosclerosis. Here, we found that hsa_circ_0008896 was significantly up-regulated in both in vitro and in vivo atherosclerosis models, indicating hsa_circ_0008896 was involved in the progression of atherosclerosis. Further functional analyses confirmed that knockdown of hsa_circ_0008896 decreased proliferation, migration, and invasion of VSMCs. In addition, we conducted bioinformatics analysis and found that hsa-miR-633 could directly bind to hsa_circ_0008896, which was confirmed by RNA immune-precipitation (RIP) assays. Results of proliferation, migration, and invasion assays showed that hsa-miR-633 inhibitor reversed the si-circ_0008896 phenotypes, indicating that hsa_circ_0008896 functionally bound to hsa-miR-633. At last, combining bioinformatics and experimental analyses, we found the protein target of hsa_circ_0008896/hsa-miR-633, CDC20B (cell division cycle 20B). The expression level of CDC20B was regulated by hsa-miR-633, and knockdown of CDC20B decreased proliferation, migration, and invasion of VSMCs. Taken together, hsa_circ_0008896 regulated the expression of CDC20B by sponging hsa-miR-633, and then enhanced proliferation, migration, and invasion of VSMCs to promote the progression of atherosclerosis.