Vascular cellular senescence in human atherosclerosis: The critical modulating roles of CDKN2A and CDK4/6 signaling pathways

Vascular cellular senescence promotes vascular aging and atherogenesis. Mitigating vascular cellular senescence serves as a promising therapy for atherosclerosis. Transcriptomic analysis was conducted to reveal the differentially expressed genes (DEGs) regulating cell proliferation, growth, senescence, and death in human atherosclerotic lesions vs. normal vessels. The key DEGs were screened out using Venn diagrams. Ox-LDL induced umbilical vein endothelial cells (HUVECs) and high fat diet-fed ApoE^-/- mice were utilized to construct model. We identified CDKN2A as a senescence-related DEG. The upregulated CDKN2A depressed the downstream CDK4/6 in ox-LDL treated HUVECs. Ox-LDL aggravated cell-cycle arrest, decreased cellular viability, inhibited migration, led to flattened and enlarged senescent morphology, generated ROS, and elevated β-galactosidase activity along with increment in β-galactosidase expression, which were ameliorated by CDKN2A knockdown and, conversely, were exacerbated by the addition of CDK4/6 inhibitor palbociclib. β-galactosidase activity and ROS production were significantly elevated in human and mice atherosclerotic lesions. β-galactosidase, co-localized with CD31, was obviously upregulated in atherosclerotic lesions, indicating endothelial cellular senescence in vivo. CDKN2A, co-localized with CD31, was markedly increased in atherosclerotic lesions, indicating the CDKN2A immunopositivity in endothelial cells in vivo. Colocalization of CDKN2A with CDK4/6 revealed the potential connection in vivo. Palbociclib exacerbated vascular cell senescence and atherogenesis in mice. Endothelial cellular senescence is present in atherosclerotic lesions. CDKN2A and CDK4/6 pathway is active in endothelial cellular senescence and atherogenesis, and altering CDKN2A and CDK4/6 pathway plays a critical role in alleviating endothelial cellular senescence and atherosclerosis, implying novel targets for prevention of vascular aging and atherogenesis.