Effect of ABCA1 Allele and Related LncRNA ANRIL on the Occurrence and Development of Abdominal Aortic Aneurysm

Abstract

Background: Studies have shown that foam cell formation and cholesterol leakage are important causes of abdominal aortic aneurysm (AAA), long non-coding RNA (lncRNA) antisense non-coding RNA at the INK4 locus (ANRIL) is a biomarker for diagnosing AAA, and ATP-binding cassette transporter A1 (ABCA1) is involved in cholesterol transport. However, the mechanism of action of ABCA1 and ANRIL in AAA is unclear. This work mainly explored the effect of the RR, RK and KK genotypes of the R219K locus of the ABCA1 and ANRIL on the occurrence and development of AAA. Methods: In this study, quantitative reverse transcription polymerase chain reaction (RT-qPCR) was used to detect the expression of ABCA1 and ANRIL in AAA and normal tissues. Eukaryotic expression vectors (RR, RK, KK) of the ABCA1 allele were introduced into vascular smooth muscle cells (VSMCs) or human monocytic leukemia cells (THP). Oil red O staining was used to detect the foam cell formation rate after THP-1 treated with oxidized low-density lipoprotein (oxLDL), and a kit was used to detect the intracellular lipid content. An enzyme-linked immunosorbent assay (ELISA) was used to detect apolipoprotein A-I (apoA-Ⅰ), high-density lipoprotein-C (HDL-C), IL-6 (interleukin-6) and TNF-α (tumor necrosis factor-α). Western blotting was used to detect MMP-2 (matrix metallo proteinase-2) and MMP-9. In addition, VSMCs were treated with angiotensin II (Ang II). The mitogen activity of VSMCs was detected by 5-ethynyl-2′-deoxyuridine (EdU) staining, and the cycle distribution and apoptosis of VSMCs were assessed by flow cytometry. Cell scratch and transwell were used to detect migration of VSMCs, and Western blotting was used to detect the expression of apoptosis-related proteins (Bcl-2 (B-cell lymphoma-2), Bax (Bcl-2 Associated X protein) and Caspase 3). Results: In AAA, ABCA1 levels were downregulated, and ANRIL were upregulated (p < 0.001). Foam cell formation and a reduction in intracellular lipid content are induced by transfection with pc-ABCA1-KK, which promotes the outflow of cholesterol from THP-1 macrophages. pc-ABCA1-KK promoted expression of apoA-Ⅰ and HDL-C while inhibiting inflammation and matrix degradation (p < 0.01). Similarly, transfection of pc-ABCA1-KK promoted cell proliferation in VSMCs (p < 0.05). However, transfection with pc-ABCA1-RK and pc-ABCA1-RR did not yield any effects. The ABCA1-KK allele can affect cholesterol metabolism in THP-1 cells and alter the biological behavior of VSMCs by inhibiting ANRIL. Conclusion: The ABCA1-KK allele affects the development of AAA by regulating ANRIL to modulate cholesterol metabolism in THP-1 cells and alter the biological behavior of VSMCs.