Abstract
BACKGROUND: N6-methyladenosine (m6A) is found in almost all nuclear RNAs of eukaryotes, playing an important and diverse role in many biological processes. Nonetheless, the roles of m6A regulators in abdominal aortic aneurysm (AAA) unknown. Therefore, there is a pressing need to identify m6A RNA methylation regulators in the diagnosis of AAA, determination of individualized risk, discovery of therapeutic targets, and improve understanding of pathogenesis. METHODS: The GSE98278 dataset were obtained from the Gene Expression Omnibus (GEO) database to perform differential analysis of m6A-related regulators between elective stable abdominal aortic aneurysms (eAAA) and abdominal aortic aneurysm ruptured (rAAA). The random forest model was used to screen candidate m6A regulators to predict the risk of rAAA. The single sample gene set enrichment analysis (ssGSEA) method was then used to evaluate the abundance of 23 immune cells in AAA. The m6A RNA Methylation Quantification Kit was used to measure the total m6A levels of AAA and normal abdominal aorta. The terminal deoxynucleotidyl transferase mediated dUTP Nick-End Labeling (TUNEL) apoptosis assay kit was used to detect the human aortic smooth muscle cells (HASMCs) apoptotic after RBM15 knockdown. Mechanically, RBM15 knockdown was found to reduce the expression of CASP3 in an m6A-dependent manner by Western blotting, RNA immunoprecipitation (RIP), and methylated RNA immunoprecipitation-quantitative polymerase chain reaction (MeRIP-RT-PCR). RESULTS: RBM15, WTAP, ALKBH5, and IGFBP3 were highly expressed in rAAA. In contrast, RBM15B showed opposite results (P<0.05). The high m6A level in the rAAA compared with eAAA and normal abdominal aorta (P<0.05). The random forest model was used to screen 5 candidate m6A regulators to predict the risk of rAAA. Expression of the 5 m6A methylation regulators was validated in AAA samples (P<0.05). RBM15 knockdown inhibited the apoptosis of HASMCs. RBM15 knockdown reduced the expression of CASP3 in an m6A-dependent manner. A strong correlation between the five m6A methylation regulators and immune cell infiltration was identified. CONCLUSIONS: In summary, m6A regulators play nonnegligible roles in the occurrence of rAAA. Our investigation of m6A patterns may be able to guide future immunotherapy strategies for AAA.