γ-Oryzanol Ameliorates Endothelial Replicative Senescence via Downregulation of SGLT2 Expression to Attenuate NADPH-Driven Oxidative Stress

Replicative senescence in endothelial cells is characterized by an irreversible cell cycle arrest and impaired endothelial function, contributing to vascular aging and cardiovascular disease. Natural compounds are being actively studied for their potential to delay cellular senescence and protect vascular health. Among them, rice bran has demonstrated several vascular benefits that are mainly attributed to gamma-oryzanol (γ-Orz), a major bioactive component in rice bran. However, its role in regulating endothelial replicative senescence and the underlying molecular mechanisms remain unclear. This study aimed to explore the protective effects of rice bran extract (RBE) and γ-Orz on replicative senescence in porcine coronary artery endothelial cells (PCAECs). Replicative senescence was modeled in PCAECs by serial passaging from P1 to P3 with varying concentrations of RBE and γ-Orz. Senescence was evaluated by measuring senescence-associated β-galactosidase (SA-β-gal) activity, cell proliferation, oxidative stress, and the expression of cell cycle regulatory proteins. RBE and γ-Orz significantly reduced SA-β-gal activity, improved proliferation, and decreased oxidative stress in P3 cells, along with downregulation of senescence-related proteins p53, p21, and p16. Additionally, γ-Orz suppressed sodium-glucose co-transporter 2 expression, reduced NADPH oxidase overexpression, and restored eNOS levels. These findings indicate that RBE and γ-Orz delay endothelial senescence by alleviating oxidative stress, highlighting their potential to reduce cardiovascular disease risk associated with endothelial senescence.