Characteristics of CXCL2 expression in coronary atherosclerosis and negative regulation by microRNA-421

OBJECTIVE: The study investigated expression of microRNA (miR)-421 in plaques, peripheral blood mononuclear cells (PBMCs), and serum from patients with coronary atherosclerosis. METHODS: Thirty-three patients with coronary atherosclerosis and 29 healthy individuals were included. Plaque tissue and adjacent intimal tissue were collected from patients. Peripheral blood was collected from patients and healthy individuals. Quantitative real-time PCR was used to determine expression of C-X-C motif chemokine ligand 2 (CXCL2) mRNA and miR-421. Western blotting was used to measure expression of CXCL2 protein in plaques and PBMCs, and ELISA was used to detect serum levels of CXCL2. A dual luciferase reporter assay was carried out to test whether CXCL2 mRNA directly interacts with miR-421. RESULTS: Patients with coronary atherosclerosis had elevated expression of CXCL2 mRNA and protein in plaques, PBMCs, and serum compared with healthy controls but reduced expression of miR-421. The dual luciferase reporter assay showed that miR-421 could bind with the 3′-untranslated seed region of CXCL2 mRNA to regulate its expression. CONCLUSION: We demonstrated that elevated expression of CXCL2 in plaques, PBMCs, and serum of patients with coronary atherosclerosis was related to downregulation of miR-421 expression. miR-421 plays a role in the occurrence of coronary atherosclerosis, probably through CXCL2.