High glucose decreases endothelial cell proliferation via the extracellular signal regulated kinase/p15INK4b pathway

High glucose inhibits endothelial cell proliferation. Thus, we studied cyclin-dependent kinase inhibitor p15(INK4b) in high glucose-induced effects in human umbilical endothelial cells at 24 h. High glucose decreased cell proliferation while arresting cells in G(0)/G(1) phase of the cell cycle. High glucose increased phospho-extracellular signal regulated kinase (ERK)1/2, p15INK4b protein and mRNA expression. High glucose-inhibited cell proliferation was attenuated by antisense p15(INK4b) oligonucleotide. Moreover, PD98059 attenuated high glucose-induced p15 (INK4b) protein expression. High glucose increased transforming growth factor-beta(TGF-beta) gene transcriptional activity and mRNA expression. However, neither SB431542 (type I TGF-beta receptor blocker) nor TGF-beta 1 antibody affected high glucose-induced p15(INK4b) protein expression. Additionally, N-acetylcysteine (an antioxidant) attenuated high glucose-induced growth arrest and p15INK4b protein expression. Thus, high glucose-induced growth arrest is dependent on p15(INK4b) and oxidative stress in endothelial cells. Moreover, high glucose-induced p15INK4b protein expression is dependent on ERKl/2 and oxidative stress. (c) 2007 Elsevier Inc. All rights reserved.