title: Anti-angiogenic effects of ribonucleic acid interference targeting vascular endothelial growth factor and hypoxia-inducible factor-1alpha.
abstract: OBJECTIVE
  To compare the in vitro anti-angiogenic effects of inhibiting vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-alpha (HIF-1alpha) using ribonucleic acid (RNA) interference (RNAi).
  
  
  METHODS
  Laboratory investigation.
  
  
  METHODS
  VEGF or HIF-1alpha was antagonized in human retinal pigment epithelial (RPE) cells using RNAi, and then cells were cultured under hypoxia. Angiogenic proteins secreted into the media were measured using enzyme-linked immunosorbent assay. Media from hypoxic RPE cells was used to grow human umbilical vein endothelial cells (HUVECs). Capillary tube formation by HUVECs was quantified and compared to assess the effectiveness of angiogenesis.
  
  
  RESULTS
  RNAi targeting VEGF caused a significant decrease in VEGF in addition to several other clinically important angiogenic factors, including angiogenin, interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and tumor growth factor beta(1) (TGF-beta(1)). Although HIF-1alpha RNAi reduced the production of VEGF, angiogenin, and TGF-beta(1), we observed an increase in the levels of several other angiogenic factors like IL-6, IL-8, and MCP-1. RNAi of VEGF and HIF-1alpha was effective in inhibiting angiogenesis, although the effect was more pronounced for VEGF RNAi.
  
  
  CONCLUSIONS
  RNAi of VEGF and HIF-1alpha may have therapeutic potential in ischemic retinal diseases like diabetic retinopathy. Targeting VEGF seems to have the advantage of decreasing the production of several clinically important angiogenic factors, thereby effectively inhibiting angiogenesis. Antagonism of HIF-1alpha may lead to the overactivation of alternate transcription factors and their respective gene products, leading to less effective inhibition of angiogenesis.
authors.affiliation: Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada. farzin.forooghian@utoronto.ca
authors.forename: Farzin
authors.initials: F
authors.lastname: Forooghian
authors.forename: Bikul
authors.initials: B
authors.lastname: Das
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000473:pathology / Q000517:prevention & control*; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D034622:RNA Interference / Q000187:drug effects*; D034741:RNA, Small Interfering / Q000494:pharmacology*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; C111835:CCL2 protein, human; D018932:Chemokine CCL2; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015850:Interleukin-6; D016209:Interleukin-8; D034741:RNA, Small Interfering; D016212:Transforming Growth Factor beta; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A