Next-Generation Sequencing of microRNAs in small abdominal aortic aneurysms: MiR-24 as a biomarker

Small abdominal aortic aneurysms (AAAs) are asymptomatic but can potentially lead to rupture if left undetected. To date, there is a lack of simple non-radiologic routine tests available for diagnosing AAAs. MicroRNAs (miRNAs) have been proven to be good-quality biomarkers in several diseases, including AAA.An attempt to identify a panel of circulating miRNAs with differential expression in AAAs via Next-Generation Sequencing (NGS) was performed in serum samples: small AAAs (n=3), large AAAs (n=3), and controls (n=3). For miR-24, validation with Real-Time PCR was undertaken in a larger group (n=80).In the NGS study, 23 miRNAs were identified as differentially expressed (with statistical significance) in small AAAs in comparison with controls. Among them, miR-24 showed the largest up-regulation with 23-fold change (log2FC 4.5, p = 0.024). For large AAAs compared with controls, and small AAAs compared with large AAAs, a panel of 33 and 131 miRNAs showed statistically significant differential expression, respectively. Based on the results of the NGS stage, a literature search was performed, and information regarding AAA pathogenesis, coronary artery disease, and peripheral arterial disease, was documented where applicable: miR-24, miR-103, miR-193a, miR-486, miR-582, and miR-3663. Out of these 6 miRNAs, miR-24 was chosen for further validation with Real-Time PCR. Additionally, in the NGS study analysis, 17 miRNAs were common between the small-large AAAs, small AAAs-controls and large AAAs-controls comparisons: miR-7846, miR-3195, miR-486-2, miR-3194, miR-5589, miR-1538, miR-3178, miR-4771-1, miR-5695, miR-6504, miR-1908, miR-6823, miR-3159, miR-23a, miR-7853, miR-496 and miR-193a. Interestingly, in the validation stage with Real-Time PCR, miR-24 was found down-regulated in small and large AAAs compared with controls (fold-changes: 0.27, p= 0.015 and 0.15, p=0.005 respectively). No correlation was found between average Ct values, aneurysm diameter, and patients' age.Our findings further highlight the importance of miR-24 as a potential biomarker as well as a therapeutic target for abdominal aneurysmal disease. Future research and validation of a panel of miRNAs for AAA would aid in diagnosis and discrimination between diseases with overlapping pathogeneses.