Insulin like Growth Factor-1 Activates Nuclear Factor-κB and Increases Transcription of the Intercellular Adhesion Molecule-1 Gene in Endothelial Cells

Abstract

A critical early event in the pathogenesis of occlusive vascular disease is the adhesion of monocytes to endothelial cells. The authors have previously reported that insulin-like growth factor-1 increases monocyte-endothelial cell adhesion and increases the expression of intercellular adhesion molecule-1. In this study, it is hypothesized that the upregulation of intercellular adhesion molecule-1 expression after treatment with insulin-like growth factor-1 is caused by an increase in the transcription of intercellular adhesion molecule-1 in endothelial cells, and that this transcription is regulated, at least in part, by activation of nuclear factor-κB. Adherence cell assays were performed using insulin-like growth factor-1 treated human umbilical vein endothelial cells and human monocytes. To determine the role of nuclear factor-κB. Western blotting using the anti-p65 (activated portion of nuclear factor-κB) was performed on cell lysate of human umbilical vein endothelial cells treated with insulin-like growth factor-1. RT-PCR was performed on RNA extracted from insulin-like growth factor-1-treated human umbilical vein endothelial cells. Intercellular adhesion molecule-1 antibody attenuated the increase in monocyte-endothelial cell adhesion of endothelial cells exposed to insulin-like growth factor-1. We observed an increase in expression of the activated nuclear factor-κB p65 protein in response to insulin-like growth factor-1 treatment. Peak increase occurred at 30 min. This effect was sensitive to pretreatment of human umbilical vein endothelial cells with the insulin-like growth factor-1 receptor antibody. Human umbilical vein endothelial cells treated with insulin-like growth factor-1 for 2 and 4 h revealed a significant increase in intercellular adhesion molecule-1 mRNA as compared with untreated human umbilical vein endothelial cells. Tumor necrosis factor-α produced a larger increase in intercellular adhesion molecule-1 mRNA expression. These results suggest that insulin-like growth factor-1 enhances intercellular adhesion molecule-1 transcription and activates nuclear factor-κB in endothelial cells. The intracellular pathways that increase cell adhesion molecule expression may provide a common link to understanding the monocyte-endothelial cell adhesion that occurs in the early stages of atherosclerosis and restenosis.