title: Prostaglandin E2 promotes integrin alpha Vbeta 3-dependent endothelial cell adhesion, rac-activation, and spreading through cAMP/PKA-dependent signaling.
abstract: We have recently reported that the inhibition of endothelial cell COX-2 by non-steroidal anti-inflammatory drugs suppresses alpha(V)beta(3)- (but not alpha(5)beta(1)-) dependent Rac activation, endothelial cell spreading, migration, and angiogenesis (Dormond, O., Foletti, A., Paroz, C., and Ruegg, C. (2001) Nat. Med. 7, 1041-1047). Here we investigated the role of the COX-2 metabolites PGE(2) and TXA2 in regulating human umbilical vein endothelial cell (HUVEC) adhesion and spreading. We report that PGE(2) accelerated alpha(V)beta(3)-mediated HUVEC adhesion and promoted Rac activation and cell spreading, whereas the TXA2 agonist retarded adhesion and inhibited spreading. We show that the cAMP level and the cAMP-regulated protein kinase A (PKA) activity are critical mediators of these PGE(2) effects. alpha(V)beta(3)-mediated adhesion induced a transient COX-2-dependent rise in cAMP levels, whereas the cell-permeable cAMP analogue 8-brcAMP accelerated adhesion, promoted Rac activation, and cell spreading in the presence of the COX-2 inhibitor NS-398. Pharmacological inhibition of PKA completely blocked alpha(V)beta(3)-mediated adhesion. A constitutively active Rac mutant (L61Rac) rescued alpha(V)beta(3)-dependent spreading in the presence of NS398 or, but did not accelerate adhesion, whereas a dominant negative Rac mutant (N17Rac) suppressed spreading without affecting adhesion. alpha(5)beta(1)-mediated HUVEC adhesion, Rac activation, and spreading were not affected by PGE(2), 8-brcAMP, or the inhibition of PKA. In conclusion, these results demonstrate that PGE(2) accelerates alpha(V)beta(3)-mediated endothelial cell adhesion through cAMP-dependent PKA activation and induces alpha(V)beta(3)-dependent spreading via cAMP- and PKA-dependent Rac activation and may contribute to the further understanding of the regulation of vascular integrins alpha(V)beta(3) by COX-2/PGE(2) during tumor angiogenesis and inflammation.
authors.affiliation: Centre Pluridisciplinaire d'Oncologie (CePO), University of Lausanne Medical School, CH-1011 Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Dormond
authors.forename: Manuela
authors.initials: M
authors.lastname: Bezzi
authors.forename: Agnese
authors.initials: A
authors.lastname: Mariotti
authors.forename: Curzio
authors.initials: C
authors.lastname: Ruegg
mesh_terms: D001483:Base Sequence; D002448:Cell Adhesion / Q000502:physiology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D017931:DNA Primers; D015232:Dinoprostone / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000502:physiology*; D015398:Signal Transduction; D020744:rac GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D039302:Integrin alphaVbeta3; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020744:rac GTP-Binding Proteins; D015232:Dinoprostone