title: Potent inhibition of VEGFR-2 activation by tight binding of green tea epigallocatechin gallate and apple procyanidins to VEGF: relevance to angiogenesis.
abstract: METHODS
  Excessive concentrations of vascular endothelial growth factor (VEGF) drive angiogenesis and cause complications such as increased growth of tumours and atherosclerotic plaques. The aim of this study was to determine the molecular mechanism underlying the potent inhibition of VEGF signalling by polyphenols.
  
  
  RESULTS
  We show that the polyphenols epigallocatechin gallate from green tea and procyanidin oligomers from apples potently inhibit VEGF-induced VEGF receptor-2 (VEGFR-2) signalling in human umbilical vein endothelial cells by directly interacting with VEGF. The polyphenol-induced inhibition of VEGF-induced VEGFR-2 activation occurred at nanomolar polyphenol concentrations and followed bi-phasic inhibition kinetics. VEGF activity could not be recovered by dialysing VEGF-polyphenol complexes. Exposure of VEGF to epigallocatechin gallate or procyanidin oligomers strongly inhibited subsequent binding of VEGF to human umbilical vein endothelial cells expressing VEGFR-2. Remarkably, even though VEGFR-2 signalling was completely inhibited at 1 μM concentrations of polyphenols, endothelial nitric oxide synthase was shown to still be activated via the PI3K/Akt signalling pathway which is downstream of VEGFR-2.
  
  
  CONCLUSIONS
  These data demonstrate for the first time that VEGF is a key molecular target for specific polyphenols found in tea, apples and cocoa which potently inhibit VEGF signalling and angiogenesis at physiological concentrations. These data provide a plausible mechanism which links bioactive compounds in food with their beneficial effects.
authors.affiliation: Institute of Food Research, Norwich Research Park, Norwich, UK.
authors.forename: Christina W A
authors.initials: CW
authors.lastname: Moyle
authors.forename: Ana B
authors.initials: AB
authors.lastname: Cerezo
authors.forename: Mark S
authors.initials: MS
authors.lastname: Winterbone
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Hollands
authors.forename: Yuri
authors.initials: Y
authors.lastname: Alexeev
authors.forename: Paul W
authors.initials: PW
authors.lastname: Needs
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kroon
mesh_terms: D044946:Biflavonoids / Q000378:metabolism* / Q000494:pharmacology; D001665:Binding Sites; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D003198:Computer Simulation; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D027845:Malus / Q000737:chemistry; D010766:Phosphorylation / Q000187:drug effects; D044945:Proanthocyanidins / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013662:Tea / Q000737:chemistry; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D044946:Biflavonoids; D044945:Proanthocyanidins; D013662:Tea; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C017674:procyanidin; D002392:Catechin; C045651:epigallocatechin gallate; C000588866:KDR protein, human; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: Angiogenesis; Dietary polyphenols; EGCG; Nitric oxide synthase; Procyanidin