Effect of selective proteasome inhibitors on TNF-induced activation of primary and transformed endothelial cells

The objective of this study was to assess the effects of two structurally d istinct yet; selective proteasome inhibitors (PS-341 and lactacystin) on le ukocyte adhesion, endothelial cell adhesion molecule (ECAM) expression, and nuclear factor-kappa B (NF-kappa B) activation in tumor necrosis factor (T NF)-alpha-stimulated human umbilical vein endothelial cells (HUVEC) and the transformed, HUVEC-derived, ECV cell line. We found that TNF (10 ng/ml) si gnificantly enhanced U-937 and polymorphonuclear neutrophil (PMN) adhesion to HUVEC but not to ECV; TNF also significantly enhanced surface expression of vascular cell adhesion molecule 1 and E-selectin (in HUVEC only), as we ll as intercellular adhesion molecule 1 (ICAM-1; in HUVEC and ECV). Pretrea tment of HUVEC with lactacystin completely blocked TNF-stimulated PMN adhes ion, partially blocked U-937 adhesion, and completely blocked TNF-stimulate d ECAM expression. Lactacystin attenuated TNF-stimulated ICAM-1 expression in ECV. Pretreatment of HUVEC with PS-341 partially blocked. TNF-stimulated leukocyte adhesion and ECAM expression. These effects of lactacystin and P S-341 were associated with inhibitory effects on TNF-stimulated NF-kappa B activation in both HUVEC and ECV. Our results demonstrate the importance of the 26S proteasome in TNF-induced activation of NF-kappa B, ECAM expressio n, and leukocyte-endothelial adhesive interactions in vitro.