title: Elevated Flk1 (vascular endothelial growth factor receptor 2) signaling mediates enhanced angiogenesis in beta3-integrin-deficient mice.
abstract: Tumor growth, tumor angiogenesis, and vascular endothelial growth factor (VEGF)-specific angiogenesis are all enhanced in beta(3)-integrin-null mice. Furthermore, endothelial cells isolated from beta(3)-null mice show elevated levels of Flk1 (VEGF receptor 2) expression, suggesting that beta(3)-integrin can control the amplitude of VEGF responses by controlling Flk1 levels or activity. We now show that Flk1 signaling is required for the enhanced tumor growth and angiogenesis seen in beta(3)-null mice. Moreover, beta(3)-null endothelial cells exhibit enhanced migration and proliferation in response to VEGF in vitro, and this phenotype requires Flk1 signaling. Upon VEGF stimulation, beta(3)-null endothelial cells exhibit higher levels of phosphorylated Flk1 and extracellular-related kinases 1 and 2 than wild-type endothelial cells. Furthermore, signaling via ERK1/2 is required to mediate the elevated responses to VEGF observed in beta(3)-null endothelial cells and aortic rings in vitro. These data confirm that VEGF signaling via Flk1 is enhanced in beta(3)-integrin-deficient mice and suggests that this increase may mediate the enhanced angiogenesis and tumor growth observed in these mice in vivo.
authors.affiliation: Tumour Biology Laboratory, Cancer Research UK Clinical Centre, Barts and the London, Queen Mary's School of Medicine and Dentistry, John Vane Science Centre, London, United Kingdom.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Reynolds
authors.forename: Louise E
authors.initials: LE
authors.lastname: Reynolds
authors.forename: Tobi E
authors.initials: TE
authors.lastname: Nagel
authors.forename: Julie C
authors.initials: JC
authors.lastname: Lively
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Robinson
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hicklin
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Bodary
authors.forename: Kairbaan M
authors.initials: KM
authors.lastname: Hodivala-Dilke
mesh_terms: D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D004730:Endothelium, Vascular / Q000254:growth & development / Q000378:metabolism / Q000473:pathology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D039302:Integrin alphaVbeta3 / Q000502:physiology; D039661:Integrin beta3 / Q000502:physiology*; D008175:Lung Neoplasms / Q000098:blood supply / Q000378:metabolism; D008297:Male; D008546:Melanoma, Experimental / Q000098:blood supply / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology*; D015398:Signal Transduction / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*
chemical_list: D039302:Integrin alphaVbeta3; D039661:Integrin beta3; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D048049:Extracellular Signal-Regulated MAP Kinases