title: Multiple roles for platelet GPIIb/IIIa and alphavbeta3 integrins in tumor growth, angiogenesis, and metastasis.
abstract: In vivo tumor cells interact with a variety of host cells such as endothelial cells and platelets, and these interactions are mediated by integrins GPIIb/IIIa and alphavbeta3. We used chimeric (c) 7E3 Fab (ReoPro) and murine (m) 7E3 F(ab')(2) to elucidate the role of these integrins in angiogenesis, tumor growth, and metastasis. These antibodies are potent inhibitors of GPIIb/IIIa and alphavbeta3. c7E3 Fab inhibited alphavbeta3-mediated human umbilical vein endothelial (HUVEC) and melanoma cell adhesion, migration, invasion, and basic fibroblast growth factor stimulated proliferation of HUVECs (IC(50) values range from 0.15 to 5 microg/ml for different assays). In an in vitro angiogenesis assay, c7E3 Fab inhibited basic fibroblast growth factor and platelet-stimulated capillary formation of HUVECs (IC(50) = 10 microg/ml and 15 microg/ml, respectively), demonstrating that endothelial alphavbeta3 is important for sprouting, and platelet-stimulated sprouting is mediated by GPIIb/IIIa. In an experimental metastasis assay, a single pretreatment of human melanoma cells with c7E3 Fab (2.5 microg/ml) inhibited lung colonization of the tumor cells in severe combined immunodeficient mice. In vivo, m7E3 F(ab')(2) partially inhibited growth of human melanoma tumors in nude mice compared with control-treated animals. These data suggest that tumor cell-expressed integrins are important but not the only component involved in tumor growth. Because c7E3 Fab and m7E3 F(ab')(2) do not cross-react with murine integrins, this inhibition of metastasis and tumor growth is attributable to direct blockade of human tumor alphavbeta3 integrins. m7E3 F(ab')(2) completely blocked tumor formation and growth of human melanoma tumors growing in nude rats. In this xenograft model, m7E3 F(ab')(2) simultaneously binds to both human tumor and host platelet GPIIb/IIIa and endothelial alphavbeta3 integrins, thus participating as an antiangiogenic and an antitumor agent. Collectively, these results indicate that combined blockade of GPIIb/IIIa and alphavbeta3 affords significant antiangiogenic and antitumor benefit.
authors.affiliation: Department of Biology Research, Centocor, Inc., 200 Great Valley Parkway, Malvern, PA 19355, USA. trikham@cntus.jnj.com
authors.forename: Mohit
authors.initials: M
authors.lastname: Trikha
authors.forename: Zhao
authors.initials: Z
authors.lastname: Zhou
authors.forename: Jozsef
authors.initials: J
authors.lastname: Timar
authors.forename: Erzebet
authors.initials: E
authors.lastname: Raso
authors.forename: Margaret
authors.initials: M
authors.lastname: Kennel
authors.forename: Eva
authors.initials: E
authors.lastname: Emmell
authors.forename: Marian T
authors.initials: MT
authors.lastname: Nakada
mesh_terms: D000077284:Abciximab; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001792:Blood Platelets / Q000502:physiology; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005260:Female; D005337:Fibrin / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000037:antagonists & inhibitors / Q000502:physiology; D019073:HT29 Cells; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology; D008545:Melanoma / Q000098:blood supply* / Q000188:drug therapy / Q000473:pathology* / Q000556:secondary; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000097:blood / Q000188:drug therapy / Q000473:pathology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors / Q000502:physiology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D016326:Extracellular Matrix Proteins; D005343:Fibrinolytic Agents; D007140:Immunoglobulin Fab Fragments; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019030:Receptors, Vitronectin; D016222:Fibroblast Growth Factor 2; D005337:Fibrin; D000077284:Abciximab