title: Blocking VEGFR-3 suppresses angiogenic sprouting and vascular network formation.
abstract: Angiogenesis, the growth of new blood vessels from pre-existing vasculature, is a key process in several pathological conditions, including tumour growth and age-related macular degeneration. Vascular endothelial growth factors (VEGFs) stimulate angiogenesis and lymphangiogenesis by activating VEGF receptor (VEGFR) tyrosine kinases in endothelial cells. VEGFR-3 (also known as FLT-4) is present in all endothelia during development, and in the adult it becomes restricted to the lymphatic endothelium. However, VEGFR-3 is upregulated in the microvasculature of tumours and wounds. Here we demonstrate that VEGFR-3 is highly expressed in angiogenic sprouts, and genetic targeting of VEGFR-3 or blocking of VEGFR-3 signalling with monoclonal antibodies results in decreased sprouting, vascular density, vessel branching and endothelial cell proliferation in mouse angiogenesis models. Stimulation of VEGFR-3 augmented VEGF-induced angiogenesis and sustained angiogenesis even in the presence of VEGFR-2 (also known as KDR or FLK-1) inhibitors, whereas antibodies against VEGFR-3 and VEGFR-2 in combination resulted in additive inhibition of angiogenesis and tumour growth. Furthermore, genetic or pharmacological disruption of the Notch signalling pathway led to widespread endothelial VEGFR-3 expression and excessive sprouting, which was inhibited by blocking VEGFR-3 signals. Our results implicate VEGFR-3 as a regulator of vascular network formation. Targeting VEGFR-3 may provide additional efficacy for anti-angiogenic therapies, especially towards vessels that are resistant to VEGF or VEGFR-2 inhibitors.
authors.affiliation: Molecular/Cancer Biology Laboratory and Ludwig Institute for Cancer Research, Biomedicum Helsinki and the Haartman Institute University of Helsinki, PO Box 63 (Haartmaninkatu 8), 00014 Helsinki, Finland.
authors.forename: Tuomas
authors.initials: T
authors.lastname: Tammela
authors.forename: Georgia
authors.initials: G
authors.lastname: Zarkada
authors.forename: Elisabet
authors.initials: E
authors.lastname: Wallgard
authors.forename: Aino
authors.initials: A
authors.lastname: Murtomäki
authors.forename: Steven
authors.initials: S
authors.lastname: Suchting
authors.forename: Maria
authors.initials: M
authors.lastname: Wirzenius
authors.forename: Marika
authors.initials: M
authors.lastname: Waltari
authors.forename: Mats
authors.initials: M
authors.lastname: Hellström
authors.forename: Tibor
authors.initials: T
authors.lastname: Schomber
authors.forename: Reetta
authors.initials: R
authors.lastname: Peltonen
authors.forename: Catarina
authors.initials: C
authors.lastname: Freitas
authors.forename: Antonio
authors.initials: A
authors.lastname: Duarte
authors.forename: Helena
authors.initials: H
authors.lastname: Isoniemi
authors.forename: Pirjo
authors.initials: P
authors.lastname: Laakkonen
authors.forename: Gerhard
authors.initials: G
authors.lastname: Christofori
authors.forename: Seppo
authors.initials: S
authors.lastname: Ylä-Herttuala
authors.forename: Masabumi
authors.initials: M
authors.lastname: Shibuya
authors.forename: Bronislaw
authors.initials: B
authors.lastname: Pytowski
authors.forename: Anne
authors.initials: A
authors.lastname: Eichmann
authors.forename: Christer
authors.initials: C
authors.lastname: Betsholtz
authors.forename: Kari
authors.initials: K
authors.lastname: Alitalo
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D045744:Cell Line, Tumor; D004151:Dipeptides / Q000494:pharmacology; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D009369:Neoplasms / Q000098:blood supply* / Q000188:drug therapy; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000037:antagonists & inhibitors* / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D004151:Dipeptides; D008024:Ligands; C419410:N-(N-(3,5-difluorophenacetyl)alanyl)phenylglycine tert-butyl ester; D051880:Receptors, Notch; D040321:Vascular Endothelial Growth Factor Receptor-3