title: Endostatin blocks vascular endothelial growth factor-mediated signaling via direct interaction with KDR/Flk-1.
abstract: Endostatin, a fragment of collagen XVIII, is a potent anti-angiogenic protein, but the molecular mechanism of its action is not yet clear. We examined the effects of endostatin on the biological and biochemical activities of vascular endothelial growth factor (VEGF). Endostatin blocked VEGF-induced tyrosine phosphorylation of KDR/Flk-1 and activation of ERK, p38 MAPK, and p125(FAK) in human umbilical vein endothelial cells. Endostatin also inhibited the binding of VEGF(165) to both endothelial cells and purified extracellular domain of KDR/Flk-1. Moreover, the binding of VEGF(121) to KDR/Flk-1 and VEGF(121)-stimulated ERK activation were blocked by endostatin. The direct interaction between endostatin and KDR/Flk-1 was confirmed by affinity chromatography. However, endostatin did not bind to VEGF. Our findings suggest that a direct interaction of endostatin with KDR/Flk-1 may be involved in the inhibitory function of endostatin toward VEGF actions and responsible for its potent anti-angiogenic and anti-tumor activities in vivo.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chunchon, Kangwon-Do 200-701, Korea.
authors.forename: Young-Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Sewook
authors.initials: S
authors.lastname: Hwang
authors.forename: Young-Myoeng
authors.initials: YM
authors.lastname: Kim
authors.forename: Bo-Jeong
authors.initials: BJ
authors.lastname: Pyun
authors.forename: Tae-Yoon
authors.initials: TY
authors.lastname: Kim
authors.forename: Seung-Taek
authors.initials: ST
authors.lastname: Lee
authors.forename: Yong Song
authors.initials: YS
authors.lastname: Gho
authors.forename: Young-Guen
authors.initials: YG
authors.lastname: Kwon
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology*; D043170:Collagen Type XVIII; D043169:Endostatins; D016228:Endothelial Growth Factors / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008222:Lymphokines / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D020794:Receptor Protein-Tyrosine Kinases / Q000187:drug effects / Q000502:physiology*; D017978:Receptors, Growth Factor / Q000187:drug effects / Q000502:physiology*; D040262:Receptors, Vascular Endothelial Growth Factor; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014471:Umbilical Veins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D000970:Antineoplastic Agents; D043170:Collagen Type XVIII; D043169:Endostatins; D016228:Endothelial Growth Factors; D008222:Lymphokines; D010446:Peptide Fragments; D017978:Receptors, Growth Factor; D011994:Recombinant Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D003094:Collagen; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor