Pentamethylquercetin attenuates angiotensin II-induced abdominal aortic aneurysm formation by blocking nuclear translocation of C/EBPβ at Lys253

Background: Pentamethylquercetin (PMQ) is a natural polymethyl flavonoid that possesses anti-apoptotic and other biological properties. Abdominal aortic aneurysm (AAA), a fatal vascular disease with a high risk of rupture, is associated with phenotypic switching and apoptosis of medial vascular smooth muscle cells (VSMCs). This study aimed to investigate the protective effects of PMQ on the development of AAA and the underlying mechanism. Methods: ApoE-/- mice were continuously infused with angiotensin II (Ang II) for 4 weeks to develop the AAA model. Intragastric administration of PMQ was initiated 5 days before Ang II infusion and continued for 4 weeks. In vitro, VSMCs were cultured and pretreated with PMQ, stimulated with Ang II. Real-time PCR, western blotting, and immunofluorescence staining were used to examine the roles and mechanisms of PMQ on the phenotypic switching and apoptosis of VSMCs. Results: PMQ dose-dependently reduced the incidence of Ang II-induced AAA, aneurysm diameter enlargement, elastin degradation, VSMCs phenotypic switching and apoptosis. Furthermore, PMQ also inhibited phenotypic switching and apoptosis in Ang II-stimulated VSMCs. PMQ exerted protective effects by regulating the C/EBP beta/ PTEN/AKT/GSK-3 beta axis. AAV-mediated overexpression of PTEN reduced the therapeutic effects of PMQ in the AAA model mice, suggesting that the effects of PMQ on Ang II-mediated AAA formation were related to the PTEN/AKT/GSK-3 beta axis. PMQ inhibited VSMCs phenotypic switching and apoptosis by bounding to C/EBP beta at Lys253 with hydrogen bond to regulate C/EBP beta nuclear translocation and PTEN/AKT/GSK-3 beta axis, thereby inhibiting Ang II-induced AAA formation. Conclusions: Pentamethylquercetin inhibits angiotensin II-induced abdominal aortic aneurysm formation by bounding to C/EBP beta at Lys253. Therefore, PMQ prevents the formation of AAA and reduces the incidence of AAA.