Abstract
A previous bioinformatic analysis from our group predicted that the interaction of microRNA (miRNA/miR)-15b with the acyl-CoA synthetase short chain family member 2 (ACSS2) gene was important for the development of abdominal aortic aneurysm (AAA). Apoptosis of aortic vascular smooth muscle cells (VSMCs) is a pathological feature of AAA. The present study aimed to explain the roles of miR-15b/ACSS2 in AAA by exploring their effects on the proliferation and apoptosis of aortic VSMCs. Human aortic VSMCs (T/G HA-VSMC cell line) were divided into six groups and were transfected with miR-15b-5p mimics, mimic negative control (NC), miR-15b-5p inhibitors, inhibitor NC, miR-15b-5p mimics+pcDNA3.1 and miR-15b-5p mimics+ACSS2-overexpessing vector. CCK-8 assay was used to determine cell proliferation. Annexin V-FITC/PI staining and flow cytometry assays were used to measure cell apoptosis. Dual-luciferase reporter assays were used to confirm the targeted relationship between miR-15b-5p and ACSS2. Reverse transcription-quantitative PCR and/or western blotting were used to examine the expression levels of miR-15b-5p, ACSS2 and prostaglandin-endoperoxide synthase 2 (PTGS2). Following transfection of T/G HA-VSMCs with mimics and inhibitors to respectively upregulate and downregulate miR-15b-5p, the results demonstrated that overexpression of miR-15b-5p inhibited cell proliferation and promoted cell apoptosis; silencing of miR-15b-5p obtained the opposite results. ACSS2 may be a direct target of miR-15b-5p, since the luciferase activity of a ACSS2 wild-type vector, but not that of a ACSS2 mutant reporter, was significantly inhibited by miR-15b-5p mimics compared with controls. Additionally, the expression levels of ACSS2 and its downstream gene PTGS2 were significantly reduced or increased following transfection with miR-15b-5p mimics or inhibitors, respectively. Furthermore, overexpression of ACSS2 reversed the antiproliferative and proapoptotic effects of miR-15b-5p mimics by blocking the production of PTGS2 protein. In conclusion, miR-15b-5p may promote the apoptosis and inhibit the proliferation of aortic VSMCs via targeting the ACSS2/PTGS2 axis. The present study provided preliminary evidence indicating that the miR-15b-5p/ACSS2/PTGS2 axis may be a potential target for the treatment of AAA.