Excessive proliferation and migration of vascular smooth muscle cells (VSMCs) is the main cause of arteriosclerosis obliterans (ASO). The present study aimed to investigate the role of microRNA (miR)-125b on the proliferation and migration of VSMCs. Platelet-derived growth factor-BB (PDGF-BB; 20 ng/ml) was used to treat VSMCs to establish an in vitro model of ASO. VSMCs were transfected with miR-125b mimic to overexpress miR-125. Cell Counting kit-8 (CCK-8) and BrdU assays were performed to assess the proliferative ability of VSMCs, while Transwell and wound healing assays were performed to assess the migratory ability of VSMCs. Western blot and immunofluorescence analyses were performed to detect the expression levels of angio-associated migratory cell protein (AAMP) and serum response factor (SRF) in VSMCs following transfection with miR-125b mimic or inhibitor. The results demonstrated that miR-125b expression decreased following treatment with PDGF-BB, the effects of which were reversed following transfection with miR-125b mimic. According to the CCK-8 assay, the cell proliferative ability decreased by ~50% compared with the negative control (NC) group, and ~40% at day 4 based on the BrdU assay. The results of the Transwell and wound healing assays indicated that the migratory ability of VSMCs significantly decreased in the miR-125b mimic group compared with the NC group. Furthermore, western blot and immunofluorescence analyses demonstrated that AAMP and SRF expression levels decreased following transfection with miR-125b mimic compared with the NC group, the effects of which were reversed following transfection with miR-125 inhibitor. Taken together, the results of the present study suggested that miR-125b inhibits the proliferative and migratory abilities of VSMCs by regulating the expression levels of AAMP and SRF.

Background: Circular RNAs (circRNAs) have been implicated in the pathogenesis of atherosclerosis (AS) and the migration and proliferation of vascular smooth muscle cells (VSMCs) under oxidized low-density lipoprotein (ox-LDL). Here, we defined the exact action of human circ_0007478 in VSMC migration and proliferation induced by ox-LDL. Methods: Human VSMCs (HVSMCs) were exposed to ox-LDL. Circ_0007478, microRNA (miR)-638, and rho-associated protein kinase 2 ( ROCK2) levels were gauged by quantitative real-time PCR (qRT-PCR) and western blot. Cell viability and proliferation were assessed by MTT and EdU assays, respectively. Transwell assays were used to detect cell migration and invasion. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-638 and circ_0007478 or ROCK2. Results: Our data indicated that circ_0007478 expression was augmented in AS serum samples and ox-LDL-treated HVSMCs. Depletion of circ_0007478 attenuated HVSMC proliferation, migration, and invasion induced by ox-LDL. Mechanistically, circ_0007478 targeted miR-638 by directly pairing to miR-638. Reduction of miR-638 reversed the effects of circ_0007478 depletion on ox-LDL-evoked proliferation, migration, and invasion in HVSMCs. ROCK2 was a direct miR-638 target and miR-638-mediated inhibition of ROCK2 relieved ox-LDL-evoked HVSMC proliferation, migration, and invasion. Furthermore, circ_0007478 was identified as a competing endogenous RNA (ceRNA) for miR-638 to modulate ROCK2 expression. Conclusion: Our present study establishes an undescribed ceRNA regulatory network, in which circ_0007478 targets miR-638 to upregulate ROCK2, thereby contributing to ox-LDL-induced proliferation and migration in HVSMCs.

No abstract

Arteriosclerosis occlusive (ASO) is a manifestation of atherosclerosis (AS), and it is one of the main causes of lower limb ischemic necrosis in the elderly. Excessive proliferation and migration of vascular smooth muscle cells is one of the main causes of ASO, but the mechanism is unclear. MiR-125b is a tumor suppressor, which can inhibit the proliferation and migration in various kinds of tumors. At the same time, we find miR-125b is the most obviously down-regulated microRNA in ASO. Therefore, we explore the role of miR-125b in ASO. This study shows that up-regulated miR-125b inhibits the proliferation of vascular smooth muscle cells through CCK8 assay and Brdu assay. Meantime, the up-regulation of miR-125b restricts the migration of vascular smooth muscle cells through trans-well assay and wound healing assay. Furthermore, this study finds that up-regulated miR-125b inhibits the expression level of angio-associated migratory cell protein (AAMP) and serum response factor (SRF), which may be an important way for miR-125b to regulate the proliferation and metastasis of smooth muscle cells.