LIPOXYGENASE METABOLITES INDUCED EXPRESSION OF ADHESION MOLECULES ANDTRANSENDOTHELIAL MIGRATION OF MONOCYTE-LIKE HL-60 CELLS IS LINKED TO PROTEIN-KINASE-C ACTIVATION

Studies have shown that, among lipoxygenase metabolites examined, 15(S )-hydroperoxy-5,8,11,13-eicosa-tetraenoic acid (15[S]-HPETE), at micro molar concentrations, selectively causes injury to cultured endothelia l cells. We investigated whether physiologically relevant concentratio ns of lipoxygenase metabolites affected the expression of cell adhesio n molecules (CAMs) involved in the adhesion of leukocytes and/or the a ccumulation of leukocytes in the vascular endothelium, these being the initial events in endothelial cell injury. Among lipoxygenase metabol ites, 15(S)-HPETE and 12(S)-HETE, at nanomolar concentrations, induced surface expression of a subset of cell adhesion molecules (CAM), ICAM -1, ELAM-1, and VCAM-1, in human umbilical vein endothelial cells (HUV EC), which is associated with an increased binding activity of the tra nscription factor, NF-kappa B, to the consensus motif common to the CA M genes in the HUVEC nuclear extracts. Furthermore, 15(S)-HPETE (1 nM) caused a threefold increase in the rate of transendothelial migration of vitamin D-3-differentiated HL-60 monocyte-like cells and showed a thirtyfold increase in the phosphorylation of PECAM-1, an adhesion mol ecule involved in endothelial cell-cell adhesion. Both an antibody to PECAM-1 and the protein kinase C inhibitor, GF 109203X, reduced 15(S)- HPETE-induced transmigration of monocyte-like HL-60 cells by approxima tely 75% and 85%, respectively. Treatment of HUVEC with a phosphatase inhibitor, calyculin A, augmented both the phosphorylation of PECAM-1 and transmigration of monocyte-like HL-60 cells induced by 15(S)-HPETE . Our results show that 15(S)-HPETE, at physiological concentrations, induced activation of protein kinase C in HUVEC and leads to the phosp horylation of PECAM-1, thus facilitating the migration of monocyte-lik e HL-60 cells across the endothelial cell monolayer. It is suggested t hat phosphorylation/dephosphorylation events in PECAM-1 are important in regulating the trafficking of monocytes across the endothelial cell monolayer. (C) 1996 Wiley-Liss, Inc.