title: Hypoxia-induced vascular endothelial growth factor secretion by retinal pigment epithelial cells is inhibited by melatonin via decreased accumulation of hypoxia-inducible factors-1α protein.
abstract: BACKGROUND
  Hypoxia is the most important stimulus leading to up-regulation of vascular endothelial growth factor (VEGF) in the retina via elevation of hypoxia-inducible factors-1α (HIF-1α) protein. The purpose of this study was to test the effects of melatonin on the expression of VEGF and HIF-1α in the cultured human retinal pigment epithelial (RPE) cells under normoxia and hypoxia.
  
  
  METHODS
  An in vitro RPE cell hypoxia model was established by placing cells under 1% oxygen pressure or by adding cobalt chloride (CoCl2) to the culture medium. RPE cells and conditioned media were collected from cultures treated with and without melatonin under normoxia and hypoxia. The protein and RNA levels of VEGF and HIF-1α were measured by ELISA kits and RT-PCR, respectively.
  
  
  RESULTS
  Hypoxia induced a significant increase of expression and secretion of VEGF and accumulation of HIF-1α protein in RPE cells (P < 0.05). Melatonin at 10-5to 10-8M significantly inhibited hypoxia-induced expression, the secretion of VEGF and the accumulation of HIF-1α protein (P < 0.05), but not affected expression of VEGF and HIF-1α under normoxia (P > 0.05).
  
  
  CONCLUSIONS
  This study suggests that melatonin may have potential value in the prevention and treatment of various retinal diseases associated with increase of VEGF, vascular leakage and angiogenesis.
authors.affiliation: Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.|Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yu-Hung
authors.initials: YH
authors.lastname: Lai
authors.affiliation: New York Eye and Ear Infirmary of Mount Sinai, New York, New York, USA.|Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Dan-Ning
authors.initials: DN
authors.lastname: Hu
authors.affiliation: New York Eye and Ear Infirmary of Mount Sinai, New York, New York, USA.|Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Rosen
authors.affiliation: New York Eye and Ear Infirmary of Mount Sinai, New York, New York, USA.
authors.forename: Jodi
authors.initials: J
authors.lastname: Sassoon
authors.affiliation: Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Lea-Yea
authors.initials: LY
authors.lastname: Chuang
authors.affiliation: Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Kwou-Yeung
authors.initials: KY
authors.lastname: Wu
authors.affiliation: Department of Ophthalmology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Wen-Chuan
authors.initials: WC
authors.lastname: Wu
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000494:pharmacology; D002470:Cell Survival; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006801:Humans; D000860:Hypoxia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics*; D008550:Melatonin / Q000494:pharmacology*; D012313:RNA / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012164:Retinal Diseases / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D042461:Vascular Endothelial Growth Factor A; D012313:RNA; D008550:Melatonin
keywords: VEGF; hypoxia; hypoxia-inducible factors-1α; melatonin; retinal pigment epithelial cells