Reactive oxygen species-induced long intergenic noncoding RNA p21 accelerates abdominal aortic aneurysm formation by promoting secretary smooth muscle cell phenotypes.

Whether long noncoding RNAs participate in the formation of abdominal aortic aneurysms (AAAs) through the regulation of SMC phenotypic switching is unknown. lincRNA-p21 induced by reactive oxygen species (ROS) is likely functionally associated with SMC phenotypic switching. We thus investigated the role of lincRNA-p21 in SMC phenotypic switching-associated AAA formation and its underlying mechanisms. An analysis of human and mouse abdominal aortic samples revealed that the lincRNA-p21 levels were significantly higher in AAA tissue. Stimulation with hydrogen peroxide upregulated the expression of lincRNA-p21 in a dose-dependent manner and converted SMCs from a contractile phenotype to a synthetic, proteolytic, and proinflammatory phenotype in vitro. Moreover, lincRNA-p21 promoted fracture of elastic fibres, reconstruction of the vascular wall, and AAA formation in vivo by modulating SMC phenotypic switching in two mouse models of AAA induced by angiotensin II or porcine pancreatic elastase (PPE) perfusion. Using a bioinformatics prediction method and luciferase reporter gene assays, we further proved that lincRNA-p21 sponged miR-204-5p to release the transcriptional activity of Mekk3 and promoted the NF-κB pathway and thereby played a role in the SMC phenotypic switch and AAA formation. The ROS levels were positively correlated with the lincRNA-p21 levels in human and mouse AAA tissues. The knockdown of lincRNA-p21 in a PPE-induced mouse AAA model increased the miR-204-5p levels and reduced the expression of Mekk3, whereas lincRNA-p21 overexpression had the opposite effect. Collectively, the results indicated that ROS-induced lincRNA-p21 sponges miR-204-5p to accelerate synthetic and proinflammatory SMC phenotypes through the Mekk3/NF-κB pathway in AAA formation. Thus, lincRNA-p21 may have therapeutic potential for AAA formation.