PGE2 accelerates αVβ3-mediated endothelial cell adhesion through cAMP-dependent PKA activation and induces αVβ3-dependent spreading via cAMP- and PKA-dependent Rac activation, providing mechanistic insights into tumor angiogenesis and inflammation.
We have recently reported that the inhibition of endothelial cell COX-2 by non-steroidal anti-inflammatory drugs suppresses αVβ3- (but not α5β1-) 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 PGE2 and TXA2 in regulating human umbilical vein endothelial cell (HUVEC) adhesion and spreading. We report that PGE2 accelerated αVβ3-mediated HUVEC adhesion and promoted Rac activation and cell spreading, whereas the TXA2 agonist U46619 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 PGE2 effects. αVβ3-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 αVβ3-mediated adhesion. A constitutively active Rac mutant (L61Rac) rescued αVβ3-dependent spreading in the presence of NS398 or U46691, but did not accelerate adhesion, whereas a dominant negative Rac mutant (N17Rac) suppressed spreading without affecting adhesion. α5β1-mediated HUVEC adhesion, Rac activation, and spreading were not affected by PGE2, U46691, 8-brcAMP, or the inhibition of PKA. In conclusion, these results demonstrate that PGE2 accelerates αVβ3-mediated endothelial cell adhesion through cAMP-dependent PKA activation and induces αVβ3-dependent spreading via cAMP- and PKA-dependent Rac activation and may contribute to the further understanding of the regulation of vascular integrins αVβ3 by COX-2/PGE2during tumor angiogenesis and inflammation. We have recently reported that the inhibition of endothelial cell COX-2 by non-steroidal anti-inflammatory drugs suppresses αVβ3- (but not α5β1-) 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 PGE2 and TXA2 in regulating human umbilical vein endothelial cell (HUVEC) adhesion and spreading. We report that PGE2 accelerated αVβ3-mediated HUVEC adhesion and promoted Rac activation and cell spreading, whereas the TXA2 agonist U46619 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 PGE2 effects. αVβ3-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 αVβ3-mediated adhesion. A constitutively active Rac mutant (L61Rac) rescued αVβ3-dependent spreading in the presence of NS398 or U46691, but did not accelerate adhesion, whereas a dominant negative Rac mutant (N17Rac) suppressed spreading without affecting adhesion. α5β1-mediated HUVEC adhesion, Rac activation, and spreading were not affected by PGE2, U46691, 8-brcAMP, or the inhibition of PKA. In conclusion, these results demonstrate that PGE2 accelerates αVβ3-mediated endothelial cell adhesion through cAMP-dependent PKA activation and induces αVβ3-dependent spreading via cAMP- and PKA-dependent Rac activation and may contribute to the further understanding of the regulation of vascular integrins αVβ3 by COX-2/PGE2during tumor angiogenesis and inflammation. Tumor angiogenesis, i.e. the formation of new blood vessels in response to angiogenic stimuli, promotes tumor progression by stimulating tumor cell survival, tumor invasion, and metastasis formation (1Carmeliet P. Jain R.K. Nature. 2000; 407: 249-257Crossref PubMed Scopus (7531) Google Scholar). Many molecules involved in mediating or regulating angiogenesis have been identified (2Yancopoulos G.D. Davis S. Gale N.W. Rudge J.S. Wiegand S.J. Holash J. Nature. 2000; 407: 242-248Crossref PubMed Scopus (3298) Google Scholar). They include growth factors (i.e. vascular endothelial growth factors, VEGF) 1The abbreviations used for: VEGF, vascular endothelial growth factor; AC, adenylcyclase; COX, cyclooxygenase; EP, E-prostanoid; HUVEC, human umbilical vein endothelial cells; NSAIDs, non-steroidal anti-inflammatory drugs; PAK, p21-activated kinase; PBS, phosphate-buffered saline; PGE, prostaglandin E; PGI, prostaglandin I; PKA, protein kinase A; PLA2, phospholipase A 2; PMSF, phenylmethylsulfonyl fluoride; TXA2, thromboxane A2. and their cell surface receptors, matrix-degrading enzymes (e.g. matrix metalloproteinases), vascular remodeling ligands, and receptors (i.e. angiopoietins and Tie receptors) and adhesion receptors of the integrin and cadherin families. Integrins are the main receptors for extracellular matrix proteins and consist of two non-covalently associated α and β subunits (3Hynes R.O. Trends Cell Biol. 1999; 9: M33-M37Abstract Full Text Full Text PDF PubMed Scopus (256) Google Scholar). Integrin ligand binding affinity and adhesion-promoting activity are regulated by intracellular events (“inside out” signaling) (4Kolanus W. Seed B. Curr. Opin. Cell Biol. 1997; 9: 725-731Crossref PubMed Scopus (128) Google Scholar). Upon ligand binding, integrins rapidly cluster and recruit structural (e.g. α-actinin, talin, vinculin) and signaling (e.g. focal adhesion kinase, paxillin, c-Src) proteins to form characteristic structures called focal contacts or focal adhesions (5Sastry S.K. Burridge K. Exp. Cell Res. 2000; 261: 25-36Crossref PubMed Scopus (429) Google Scholar). Integrins and focal adhesions propagate tensional forces between the extracellular matrix and the cytoskeleton necessary to stabilize cell adhesion and initiate signaling events essential to cell survival, proliferation and differentiation (“outside in” signaling) (6Giancotti F.G. Ruoslahti E. Science. 1999; 285: 1028-1032Crossref PubMed Scopus (3829) Google Scholar). Integrin αVβ3 is highly expressed in angiogenic endothelial cells but not, or to a much lower extent, in quiescent endothelial cells (7Brooks P.C. Montgomery A.M. Rosenfeld M. Reisfeld R.A. Hu T. Klier G. Cheresh D.A. Cell. 1994; 79: 1157-1164Abstract Full Text PDF PubMed Scopus (2185) Google Scholar, 8Max R. Gerritsen R.R. Nooijen P.T. Goodman S.L. Sutter A. Keilholz U. Ruiter D.J. De Waal R.M. Int. J. Cancer. 1997; 71: 320-324Crossref PubMed Scopus (169) Google Scholar, 9Sipkins D.A. Cheresh D.A. Kazemi M.R. Nevin L.M. Bednarski M.D. Li K. Nat. Med. 1998; 4: 623-626Crossref PubMed Scopus (837) Google Scholar). Several studies have demonstrated that αVβ3 antagonists effectively inhibit angiogenesis, including tumor angiogenesis. An anti-αVβ3 function-blocking mAb or an antagonistic RGD-based cyclic peptide suppressed cornea vascularization (10Friedlander M. Brooks P.C. Shaffer R.W. Kincaid C.M. Varner J.A. Cheresh D.A. Science. 1995; 270: 1500-1502Crossref PubMed Scopus (1225) Google Scholar), retinal neovascularization (11Hammes H.P. Brownlee M. Jonczyk A. Sutter A. Preissner K.T. Nat. Med. 1996; 2: 529-533Crossref PubMed Scopus (314) Google Scholar), and tumor angiogenesis (7Brooks P.C. Montgomery A.M. Rosenfeld M. Reisfeld R.A. Hu T. Klier G. Cheresh D.A. Cell. 1994; 79: 1157-1164Abstract Full Text PDF PubMed Scopus (2185) Google Scholar, 13Brooks P.C. Stromblad S. Klemke R. Visscher D. Sarkar F.H. Cheresh D.A. J. Clin. Invest. 1995; 96: 1815-1822Crossref PubMed Scopus (757) Google Scholar). Tumstatin, an endogenous degradation fragment of collagen IV, suppresses tumor angiogenesis by interacting with αVβ3 and inhibiting protein synthesis in endothelial cells (14Maeshima Y. Sudhakar A. Lively J.C. Ueki K. Kharbanda S. Kahn C.R. Sonenberg N. Hynes R.O. Kalluri R. Science. 2002; 295: 140-143Crossref PubMed Scopus (397) Google Scholar). Furthermore, disruption of tumor vessels by high doses of tumor necrosis factor and interferon γ is associated with the inhibition of the αVβ3 function in endothelial cells (15Ruegg C. Yilmaz A. Bieler G. Bamat J. Chaubert P. Lejeune F.J. Nat. Med. 1998; 4: 408-414Crossref PubMed Scopus (428) Google Scholar). Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used therapeutics for the treatment of pain and inflammation. NSAIDs act by inhibiting cyclooxygenase (COX) activity and the synthesis of prostaglandins and thromboxans (16Vane J.R. Bakhle Y.S. Botting R.M. Annu. Rev. Pharmacol. Toxicol. 1998; 38: 97-120Crossref PubMed Scopus (2620) Google Scholar). There are two known COX isoforms: 1) COX-1, which is ubiquitously expressed and contributes to tissue homeostasis, and 2) COX-2, which is expressed in activated leukocytes and cancer cells and promotes inflammation and cancer progression (17Dubois R.N. Abramson S.B. Crofford L. Gupta R.A. Simon L.S. Van De Putte L.B. Lipsky P.E. FASEB J. 1998; 12: 1063-1073Crossref PubMed Scopus (2231) Google Scholar). Prolonged intake of NSAIDs, including COX-2 inhibitors, significantly decreases the risk of developing colon cancer and suppresses the progression of pre-malignant lesions (polyps) (18Oshima M. Dinchuk J.E. Kargman S.L. Oshima H. Hancock B. Kwong E. Trzaskos J.M. Evans J.F. Taketo M.M. Cell. 1996; 87: 803-809Abstract Full Text Full Text PDF PubMed Scopus (2286) Google Scholar, 19Steinbach G. Lynch P.M. Phillips R.K. Wallace M.H. Hawk E. Gordon G.B. Wakabayashi N. Saunders B. Shen Y. Fujimura T. Su L.K. Levin B. N. Engl. J. Med. 2000; 342: 1946-1952Crossref PubMed Scopus (2299) Google Scholar, 20Gupta R.A. DuBois R.N. Nat. Rev. Cancer. 2001; 1: 11-21Crossref PubMed Scopus (958) Google Scholar). Moreover, NSAIDs suppress the progression of established experimental tumors in mice (21Goldman A.P. Williams C.S. Sheng H. Lamps L.W. Williams V.P. Pairet M. Morrow J.D. DuBois R.N. Carcinogenesis. 1998; 19: 2195-2199Crossref PubMed Scopus (150) Google Scholar, 22Shiff S.J. Rigas B. J. Exp. Med. 1999; 190: 445-450Crossref PubMed Scopus (143) Google Scholar). Recent reports indicate that the anti-tumor activity of NSAID involves the inhibition of tumor angiogenesis (23Tsujii M. Kawano S. Tsuji S. Sawaoka H. Hori M. DuBois R.N. Cell. 1998; 93: 705-716Abstract Full Text Full Text PDF PubMed Scopus (2216) Google Scholar, 24Masferrer J.L. Leahy K.M. Koki A.T. Zweifel B.S. Settle S.L. Woerner B.M. Edwards D.A. Flickinger A.G. Moore R.J. Seibert K. Cancer Res. 2000; 60: 1306-1311PubMed Google Scholar). COX-2 inhibitors decrease VEGF production in fibroblasts and tumor cells and prevent VEGF-induced MAPK activation in endothelial cells (23Tsujii M. Kawano S. Tsuji S. Sawaoka H. Hori M. DuBois R.N. Cell. 1998; 93: 705-716Abstract Full Text Full Text PDF PubMed Scopus (2216) Google Scholar, 25Jones M.K. Wang H. Peskar B.M. Levin E. Itani R.M. Sarfeh I.J. Tarnawski A.S. Nat. Med. 1999; 5: 1418-1423Crossref PubMed Scopus (801) Google Scholar), block αVβ3-mediated endothelial cell spreading and migration in vitro, and suppress fibroblast growth factor 2-induced angiogenesis in vivo (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google Scholar). This latter effect was not associated with any detectable changes in either integrin cell surface expression or integrin affinity. We identified suppression of αVβ3-dependent activation of the small GTPases Cdc42 and Rac the by which NSAIDs suppress spreading. of but not TXA2, rescued NSAID that prostaglandins are critical of αVβ3-mediated endothelial cell spreading and we these by that prostaglandin accelerated αVβ3-mediated endothelial cell adhesion through the cAMP-dependent activation of protein kinase A (PKA) and induced spreading via cAMP- and PKA-dependent activation of In α5β1-mediated endothelial cell adhesion was not regulated by PGE2, intracellular cAMP levels, or PKA human and phenylmethylsulfonyl were and were PGE2, 8-brcAMP, and were U46619 was mAb was was umbilical vein endothelial cells (HUVEC) were and (15Ruegg C. Yilmaz A. Bieler G. Bamat J. Chaubert P. Lejeune F.J. Nat. Med. 1998; 4: 408-414Crossref PubMed Scopus (428) Google for the of a HUVEC were and for with of or or and of in without and with a HUVEC were in and for in the was by the of protein by were with or in and were (15Ruegg C. Yilmaz A. Bieler G. Bamat J. Chaubert P. Lejeune F.J. Nat. Med. 1998; 4: 408-414Crossref PubMed Scopus (428) Google Scholar). HUVEC were in a and and cells were by the with cells were in with and by an are and the of of adhesion to the adhesion an extracellular matrix protein the adhesion not were the of and used the PGE2, 8-brcAMP, and spreading the of cells was in high cells were small cells with or whereas cells were cells with (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google Scholar). the of cells in high HUVEC were or in with cells were with and in PMSF, and were with of in the presence of were by and in and the proteins were in and by a to Rac was in cell was used for HUVEC were or for HUVEC were in PBS, and cAMP was with and an to the were to the protein a protein and expressed HUVEC were in a in or the cells were in and with PMSF, PKA activity was by the of in the PKA activity was to protein and expressed of of was HUVEC the of were and was to for and by Sheng H. J. M.K. DuBois R.N. J. Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). were and were of and We have reported that NSAIDs suppressed αVβ3-dependent endothelial cell spreading and migration and that effect was by of prostaglandins (i.e. PGE2 or results identified COX-2 and prostaglandins critical of vascular integrin αVβ3 function (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google Scholar). the role of prostaglandins in the regulation of αVβ3 function in we the of PGE2 and TXA2, two in the of angiogenesis H. Morrow J.D. Cancer Res. 1999; Google Scholar, R. Exp. Biol. Med. PubMed Scopus Google Scholar), the adhesion and spreading of human umbilical vein endothelial HUVEC and through integrin whereas integrin to to (15Ruegg C. Yilmaz A. Bieler G. Bamat J. Chaubert P. Lejeune F.J. Nat. Med. 1998; 4: 408-414Crossref PubMed Scopus (428) Google Scholar). and and adhesion and spreading were and A and and adhesion and spreading with a and were and A and of PGE2 adhesion or accelerated HUVEC cell in a to a to adhesion and adhesion was of the presence or of of HUVEC adhesion and induced by PGE2 was by an in the spreading HUVEC spreading was not further accelerated by TXA2 analogue U46619 a but of HUVEC adhesion and the inhibition of spreading and in a suppression of cell adhesion and an inhibition of spreading a of and U46619 effect HUVEC adhesion or spreading to and promotes and αVβ3-mediated cell spreading. HUVEC were or in the or presence of PGE2 or U46619 cells were and and by the of cells cells in high these results we that PGE2 accelerated the αVβ3-dependent HUVEC adhesion and spreading and adhesion and suppressed spreading. α5β1-mediated HUVEC adhesion and spreading were not PGE2 to and the and M.D. R.M. Curr. Opin. 2000; 9: PubMed Scopus Google Scholar). which was involved in mediating the PGE2 we the expression by for and but not and were demonstrate the of and receptors, we adhesion in the or presence of a and a accelerated HUVEC adhesion to with for PGE2 effect HUVEC adhesion to not effect not these results and receptors PGE2 receptors PGE2 and TXA2 of their through R.A. S. Pharmacol. Rev. 1994; Google Scholar). the PGE2 αVβ3-mediated HUVEC adhesion involved of cAMP levels, we cAMP in HUVEC in response to adhesion to or a transient rise in cAMP whereas adhesion a rise that was with the cAMP were and to and in the presence of U46619 completely the rise in cAMP level but suppressed the cAMP HUVEC adhesion or in the presence of PGE2 in cAMP and in cAMP in response to HUVEC adhesion to was completely by and effect was by the of PGE2, whereas the rise in cAMP induced by adhesion to was to treatment for a role of cAMP in αVβ3-dependent adhesion and spreading, we HUVEC in the or presence of the cell-permeable cAMP 8-brcAMP and 8-brcAMP accelerated HUVEC adhesion, and effect was to or U46619 the of of and HUVEC to of 8-brcAMP induced HUVEC spreading in the presence of or U46619 results were by cAMP with not these demonstrate that αVβ3-mediated HUVEC adhesion results in a transient and COX-2-dependent in cAMP levels, whereas α5β1-mediated adhesion induces a and COX-2 cAMP of 8-brcAMP accelerates αVβ3-dependent HUVEC adhesion in the presence of a COX-2 small protein Rac is a critical of cell spreading Trends Cell Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). COX-2 activity and prostaglandin production are essential for αVβ3-dependent Rac activation in HUVEC (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google Scholar). In of the of 8-brcAMP to cell spreading in the presence of we the of 8-brcAMP was to the inhibition of αVβ3-mediated Rac activation by NS-398. we the activation of Rac in HUVEC and a HUVEC adhesion and in activation of Rac with and we Rac activity in HUVEC in the or presence of 8-brcAMP, or a of adhesion completely inhibited Rac activation, and effect was completely by the of 8-brcAMP of 8-brcAMP adhesion in a in Rac activity with adhesion we the of Rac activation was involved in mediating the of αVβ3-dependent HUVEC adhesion and HUVEC spreading in response to these we HUVEC with an expression for a active (L61Rac) or a dominant negative form (N17Rac) of Rac (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google and the and spreading of these did not accelerate HUVEC adhesion to and did not Rac did not prevent the of HUVEC adhesion induced by 8-brcAMP, and did not prevent the adhesion by In the inhibition of HUVEC spreading by and U46691, whereas suppressed HUVEC spreading, and effect was not by 8-brcAMP these results we that αVβ3-dependent HUVEC spreading in response to cAMP Rac activation, whereas of αVβ3-dependent HUVEC adhesion kinase A was reported to αVβ3-dependent angiogenesis S. M. Varner J.A. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google and migration of cells A.M. J. Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). cAMP PKA activation, we HUVEC adhesion to or promoted PKA A PKA activity was the of and adhesion induced a transient in PKA activity suppressed PKA activation but did not inhibit PKA whereas the PKA inhibitor suppressed and PKA activity PGE2 induced a PKA activation in the presence of HUVEC adhesion to induced a in PKA which was completely to PKA activity was for αVβ3- and HUVEC adhesion and spreading, we cells and in the or presence of suppressed HUVEC adhesion to whereas effect HUVEC adhesion and Furthermore, the of 8-brcAMP did not inhibition of cell adhesion In we investigated the of PKA in αVβ3- and Rac completely suppressed αVβ3-dependent Rac activation, whereas did not α5β1-mediated Rac activation of PGE2 or 8-brcAMP did not inhibition of αVβ3-dependent Rac activation by We constitutively active Rac the suppression of αVβ3-dependent HUVEC adhesion by of demonstrated that expression of was not to suppression of αVβ3-dependent HUVEC adhesion by HUVEC in the presence of with the activation of Rac in the presence of HUVEC adhesion to these we that PKA activity and αVβ3-dependent HUVEC adhesion and Rac activation and that active Rac not cell adhesion in the of PKA In PKA is not for cell adhesion and spreading. COX-2 expression in tumor cells and the tumor promotes tumor and effect involves the of tumor angiogenesis. COX-2 have VEGF tumor angiogenesis, and suppressed tumor growth C.S. M. J. S.K. DuBois R.N. J. Clin. Invest. 2000; PubMed Scopus Google Scholar). COX-2 inhibitors decrease VEGF production in fibroblasts and tumor cells and prevent protein kinase activation in response to VEGF (23Tsujii M. Kawano S. Tsuji S. Sawaoka H. Hori M. DuBois R.N. Cell. 1998; 93: 705-716Abstract Full Text Full Text PDF PubMed Scopus (2216) Google Scholar, 25Jones M.K. Wang H. Peskar B.M. Levin E. Itani R.M. Sarfeh I.J. Tarnawski A.S. Nat. Med. 1999; 5: 1418-1423Crossref PubMed Scopus (801) Google Scholar, C.S. M. J. S.K. DuBois R.N. J. Clin. Invest. 2000; PubMed Scopus Google Scholar). Pharmacological inhibition of COX-2 in endothelial cells αVβ3-mediated Rac activation, in cell spreading and migration in and suppressed vivo (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google Scholar). of the PGE2 and TXA2, have been to angiogenesis H. Morrow J.D. Cancer Res. 1999; Google R. Exp. Biol. Med. PubMed Scopus Google Scholar), but the involved are In we have investigated the effect of PGE2 and TXA2 αVβ3- and α5β1-mediated HUVEC adhesion and spreading. Here we report the PGE2 accelerated HUVEC adhesion, induced and spreading by integrin whereas the TXA2 agonist adhesion and inhibited spreading by PGE2 to HUVEC through receptors and αVβ3-mediated HUVEC adhesion in a transient rise in cAMP and activation of the cAMP-dependent PKA. αVβ3-mediated HUVEC adhesion PKA but not Rac whereas αVβ3-mediated spreading PKA and Rac integrin HUVEC adhesion and Rac activation and spreading were not regulated by or TXA2 and did not PKA these demonstrate that αVβ3-dependent HUVEC adhesion and spreading are regulated by PGE2 through whereas α5β1-mediated adhesion and spreading of There is that cAMP regulated by integrin the that cAMP contributes to the of integrin integrin induces cell migration by stimulating a rise in intracellular cAMP J.L. Cell. Biol. Res. 2000; 4: PubMed Scopus Google Scholar). by which integrin to an in cAMP level is not completely results the of two and involves αVβ3-mediated and COX-2-dependent production of PGE2, the of receptors, and the activation of This is with the of COX-2 activity to a cAMP rise in response to αVβ3 cell spreading and migration (26Dormond O. Foletti A. Paroz C. Ruegg C. Nat. Med. 2001; 7: 1041-1047Crossref PubMed Scopus (272) Google with the signaling of prostaglandins R.A. DuBois R.N. Nat. Rev. Cancer. 2001; 1: 11-21Crossref PubMed Scopus (958) Google Scholar). of COX-2-dependent PGE2 production αVβ3-dependent adhesion the αVβ3-mediated activation of phospholipase and the production of the of In been recently reported that αVβ3 induces and activation of with the of in endothelial cells S. R. N. S. K. J. J. Cell. 2001; PubMed Google Scholar). to by integrin in cell and in activation been to the production of the activation of and cell spreading B.S. Biol. Cell. 1995; PubMed Scopus Google Scholar, Hynes R.O. J. Biol. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). involves activation of This is by the that not inhibit the in cAMP in HUVEC integrin with the cell binding of or with by been reported to a in intracellular cAMP and PKA activity in endothelial cells F.J. P. B. Nat. Cell. Biol. 2000; 2: PubMed Scopus Google Scholar). α inhibitors suppressed that integrin and may through the activation of F.J. P. B. Nat. Cell. Biol. 2000; 2: PubMed Scopus Google Scholar). cAMP cell adhesion and migration, the cell and or effects. an in cAMP was to adhesion of to J.E. J. 1995; Google Scholar), to inhibit adhesion of to Y. E. W. S. J. Exp. Med. PubMed Scopus Google Scholar), and to suppresses adhesion and migration in response to C. J. Biol. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar). indicate in endothelial an of cAMP accelerates αVβ3-mediated adhesion and promotes spreading via activation of PKA. cAMP-dependent PKA activation was reported to cell migration in response to growth factors through the activation of Rac and the inhibition of A.M. J. Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). There is that PKA and cell adhesion and migration of and cell endothelial and S. M. Varner J.A. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, A.M. J. Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar, J.D. S.K. J. Cell 2001; PubMed Google Scholar, G.D. K. J. A. Y. M.R. Clin. Exp. 1996; Google Scholar, S.L. J. Biol. 2002; 71: Google Scholar). by which PKA events and Rac activity in we the for the regulation of αVβ3-mediated endothelial cell adhesion and spreading by Upon αVβ3-dependent adhesion is a transient rise in cAMP and PKA activity dependent production of PGE2 and signaling through PKA activity accelerates αVβ3-dependent adhesion through a and αVβ3-dependent spreading through a In the rise in cAMP and PKA activity α5β1-mediated adhesion not COX-2 or PGE2 and is not for HUVEC adhesion and spreading. This latter that the of integrin may a cAMP rise and PKA activation, which αVβ3-dependent endothelial cell adhesion and a is with a report that of integrin αVβ3-dependent endothelial cell migration and angiogenesis S. M. Varner J.A. J. Biol. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). migration and angiogenesis is to cAMP and PKA whereas or PKA activity in adhesion. regulation of cAMP may through of cAMP by or degradation by growth cell migration was to cAMP-dependent PKA activity and cAMP degradation L.M. A.M. J. Cell Biol. 1998; PubMed Scopus Google Scholar, A.M. J. Biol. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). In conclusion, we have demonstrated that a rise in cAMP promotes αVβ3-mediated endothelial cell adhesion through the activation of PKA and induces spreading via PKA-dependent Rac results may contribute to the further understanding of the regulation of vascular integrins αVβ3 by tumor angiogenesis and inflammation. J. Lejeune for J. A. and S. for and R. for critical of the
Dormond et al. (Fri,) studied this question.