A role for c-Raf kinase and Ha-Ras in cytokine-mediated induction of cell adhesion molecules

Cytokines such as tumor necrosis factor (TNF alpha) play fundamental roles in the pathophysiology of inflammation and immunity-related diseases. Despi te rapid advances in our understanding of cytokine biology in recent years, definitive knowledge of the cytokine cell signaling pathways remains elusi ve due to the enormous complexity of these pathways and the lack of specifi c biological tools and reagents. Using highly specific antisense oligonucle otides that target the mRNA encoding c-Raf kinase and Ha-Ras, we show here that inhibition of c-raf and Ha-ras expression blocks the up-regulation of E-selectin and vascular adhesion molecule-1 induced by TNF alpha in endothe lial cells. Induction of intercellular adhesion molecule-1 was also reduced , although to a much lesser extent, by treatment with antisense oligonucleo tides. We also show that inhibition of c-raf kinase expression decreased ex tracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK) kinas e stimulation by TNF alpha. Furthermore, antisense inhibition of JNK2 also blocked TNF alpha-mediated induction of E-selectin, whereas PD98059 (mitoge n-activated protein kinase kinase 1 and 2 inhibitor) had no effect on this process. These results indicate that TNF alpha induction of E-selectin and vascular adhesion molecule-1 in endothelial cells occurs through signaling pathways that are, at least in part, dependent on c-Raf kinase, Ha-Ras, and JNK2.