This study was to explore the effects of oxidized-low density lipoprotein (ox-LDL) on the proliferation and apoptosis of macrophages, and the role of miRNA-9 in the targeted regulation of platelet-derived growth factor receptor-β (PDGFR-β) expression. Macrophage RAW264.7 cells were cultured and foamed with 100 mg/L ox-LDL to detect the cell proliferation and apoptosis and target protein expression levels. Subsequently, the miRNA-9 mimics and inhibitors were transfected to detect the expression level of PDGFR-β. The dual-luciferase reporter gene was predicted and applied to detect the target-binding effect of miRNA-9 and PDGFR-β in the cells. The results showed that ox-LDL could induce the foaming of macrophages RAW264.7, inhibit the cell proliferation, and promote the cell apoptosis. After ox-LDL induction, expression of Caspase-3 in macrophages RAW264.7 was up-regulated, and that of glucose regulated protein 78 was down-regulated. The transfection of miRNA-9 mimics could greatly inhibit the expression of PDGFR-β mRNA and proteins in the cells. In addition, the results of the dual-luciferase reporter gene showed that the ratio of luciferase activity was significantly reduced after the miRNA-9 mimic and the wild-type PDGFR-β plasmid were co-transfected. In summary, ox-LDL could induce foaming of macrophages and promote cell apoptosis, and miRNA-9 could target and bind to the 3'UTR region of PDGFR-β, thereby inhibiting the gene expression.
Keywords: Oxidized-low density lipoprotein; macrophages; microRNA-9; platelet derived growth factor receptor-β.