Linoleic acid-induced VCAM-1 expression in human microvascular endothelial cells is mediated by the NF-κB-dependent pathway

Vascular cell adhesion molecule-1 (VCAM-1) has been reported to play an important role in cancer metastasis via the adhesive interaction between tumor cells and endothelial cells. In this study, we examined the effects of linoleic acid on VCAM-1 expression and its transcriptional regulatory mechanism in human microvascular endothelial cells (HMEC-1). Time- and dose-dependent increases of VCAM] mRNA levels were observed in linoleic acid-treated HMEC-1 as detected by reverse transcriptase-polymerase chain reaction. Flow cytometry analysis showed a significant and dose-dependent upregulation of VCAM-1 expression in HMEC-1 stimulated with linoleic acid compared with controls. To clarify the transcriptional regulatory pathway, we investigated the role of nuclearfactor-kappaB (NF-kappaB) in the expression of VCAM-1 by linoleic acid in HMEC-1. Nuclear extracts from HMEC-1 stimulated with linoleic acid showed a dose-dependent increase in binding activity to the NF-kappaB consensus sequences. These effects were preventable by cotreatment with inhibitors of NF-kappaB activity, such as sodium salicylate, aspirin, or pyrrolidine dithiocarbamate. In addition, pretreatment with NF-kappaB inhibitors markedly suppressed the ability of linoleic acid to induce VCAM-1 gene expression. The role of NF-kappaB in linoleic acid-induced VCAM-1 expression was confirmed by functional promoter studies in HMEC-1 transfected with reporter constructs Of the VCAM-1 promoter with or without mutated NF-kappaB binding site. These results indicate that linoleic acid upregulates VCAM-1 expression in HMEC-1 through the NF-kappaB-dependent pathway.