Abstract 630: Cst1 Discriminates Between Senescence Due to Replicative and Stress-Induced Endothelial Cell Aging

Introduction: Senescence comprises the cellular and molecular changes leading to compromised functionality of organs. The presence of senescent endothelial cells in human atherosclerotic lesions suggests a contribution to vascular pathology. Better understanding of endothelial senescence will help identify its role in endothelial dysfunction. In this study gene expression changes were assessed in human endothelial cells following induction of senescence either by replicative or peroxide-induced stress and genes identified that were differentially expressed to be used as biomarkers of endothelial aging.

Methods: Replicative senescent endothelial cells (REPS) were established by passaging human umbilical vein endothelial cells (HUVECs) up to 25 population doublings and stress-induced premature senescence (SIPS) was induced by treating HUVECs with tertiary butyl hydrogen peroxide (t-BHP) for 1 hr for consecutive 3 days. Senescence was confirmed by staining with senescence marker SA β-gal and p53 expression through Western blotting. Gene expression changes were confirmed by qPCR using Taqman probes.

Results: REPS and SIPS cells were found to be 71 % (912 of 1285) and 81 % (980 of 1210) positive for SA-beta gal staining respectively, compared to young endothelial cells (10 % (130 of 1308); Fig1). CST1 was identified as highly expressed gene (90 fold) in REPS but not SIPS of endothelial cells in microarray gene expression analysis. Further validation using qPCR showed a 164 fold increase in CST1 expression (fig2) in REPS endothelial cells only.

Conclusion: In conclusion, this study confirms that CST1 as a new marker of replicative senescence in human endothelial cells.