title: GLP-1 promotes angiogenesis in human endothelial cells in a dose-dependent manner, through the Akt, Src and PKC pathways.
abstract: BACKGROUND
  Novel anti-diabetic medications that mimic or augment the physiological actions of GLP-1 improve cardiovascular risk factors in diabetics and GLP-1 has been proposed to have a beneficial role in the cardiovascular system. GLP-1 may have a direct cardioprotective role by decreasing infarct size and protecting from ischemia-reperfusion injury while prolonging survival in rodent models. The mechanisms underlying these observations remain largely unknown. In vitro studies suggest that GLP-1 may promote endothelial cell proliferation, but no study to date has evaluated a potential direct effect of GLP-1 on angiogenesis.
  
  
  OBJECTIVE
  To evaluate whether GLP-1 affects angiogenesis in humans and to elucidate underlying molecular mechanisms.
  
  
  METHODS
  We utilized a 3D culture system where spherules of human umbilical vein endothelial cells (HUVECs) embedded in a collagen scaffold were treated with escalating doses of human recombinant GLP-1 (50-2000 nmol/L) and the formation of new vessels was observed and quantified. Signaling inhibitors were utilized to identify molecular pathways through which GLP-1 promotes angiogenesis.
  
  
  RESULTS
  We demonstrate that GLP-1 promotes angiogenesis in a dose-dependent manner. The maximum effect on angiogenesis was observed at a GLP-1 dose of 500 nmol/L, while increased angiogenesis occurred in response to doses ranging from 200 nmol/L to 1000 nmol/L. Pre-treatment of the system with Akt inhibitor IV, Bisindolylmaleimide (PKC inhibitor) and src inhibitor I resulted in a significant decrease of the GLP-1 induced angiogenesis.
  
  
  CONCLUSIONS
  This is the first study to demonstrate that GLP-1 promotes angiogenesis in a HUVEC three dimensional in vitro model. This effect requires pharmacological doses and is mediated through the Akt, PKC and src pathways.
authors.affiliation: Division of Endocrinology, Diabetes & Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA konstantinos.aronis@bmc.org
authors.forename: Konstantinos N
authors.initials: KN
authors.lastname: Aronis
authors.forename: John P
authors.initials: JP
authors.lastname: Chamberland
authors.forename: Christos S
authors.initials: CS
authors.lastname: Mantzoros
mesh_terms: D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D052216:Glucagon-Like Peptide 1 / Q000502:physiology*; D061307:Human Umbilical Vein Endothelial Cells / Q000502:physiology; D006801:Humans; D018919:Neovascularization, Physiologic / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D052216:Glucagon-Like Peptide 1; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C
keywords: 5' adenosine monophosphate (5’AMP) -activated protein kinase; AMPK; Akt; Angiogenesis; ELISA; Endothelial Nitric Oxide Synthase; Enzyme Linked Immunosorbent Assay; FAK; FMD; Flow-Mediated Dilatation; Focal Adhesion Kinase; GLP-1; Glucagon-Like Peptide 1; HCAECs; HUVECs; Human Coronary Artery Endothelial Cells; Human Umbilical Vein Endothelial Cells; LVEF; Left Ventricular Ejection Fraction; NOS; Nitric Oxide Synthase; OD; Optical Density; PI3K; PKA; PKC; Phosphatidylinositide 3-kinase; Protein Kinase A; Protein Kinase C; STAT-3; Signal transducer and activator of transcription 3; VEGF; Vascular Endothelial Growth Factor; eNOS; src