title: Adenosine receptor activation induces vascular endothelial growth factor in human retinal endothelial cells.
abstract: Adenosine, released in increased amounts by hypoxic tissues, is thought to be an angiogenic factor that links altered cellular metabolism caused by oxygen deprivation to compensatory angiogenesis. Adenosine interacts with 4 subtypes of G protein-coupled receptors, termed A(1), A(2A), A(2B), and A(3). We investigated whether adenosine causes proliferation of human retinal endothelial cells (HRECs) and synthesis of vascular endothelial growth factor (VEGF) and, if so, which adenosine receptor subtype mediates these effects. The nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA), in a concentration-dependent manner, increased both VEGF mRNA and protein expression by HRECs, as well as proliferation. This proliferative effect of NECA was inhibited by the addition of anti-human VEGF antibody. NECA also increased insulin-like growth factor-I and basic fibroblast growth factor mRNA expression in a time-dependent manner and cAMP accumulation in these cells. In contrast, neither the A(1) agonist N(6)-cyclopentyladenosine nor the A(2A) agonist 2-p-(2-carboxyethyl) phenethylamino-NECA caused any of the above effects of NECA. The effects of NECA were not significantly attenuated by either the A(2A) antagonist SCH58261 or the A(1) antagonist 8-cyclopentyl-1, 3-dipropylxanthine. However, the nonselective adenosine receptor antagonist xanthine amine congener completely inhibited the effects of NECA. Addition of antisense oligonucleotide complementary to A(2B) adenosine receptor mRNA inhibited VEGF protein production by HRECs after NECA stimulation. Thus, the A(2B) adenosine receptor subtype appears to mediate the actions of adenosine to increase growth factor production, cAMP content, and cell proliferation of HRECs. Adenosine activates the A(2B) adenosine receptor in HRECs, which may lead to neovascularization by a mechanism involving increased angiogenic growth factor expression.
authors.affiliation: Department of Medicine, Ophthalmology and Pharmacology, University of Florida, Gainesville, Fla 32610-0226, USA. grantma@medicine.ufl.edu
authors.forename: M B
authors.initials: MB
authors.lastname: Grant
authors.forename: R W
authors.initials: RW
authors.lastname: Tarnuzzer
authors.forename: S
authors.initials: S
authors.lastname: Caballero
authors.forename: M J
authors.initials: MJ
authors.lastname: Ozeck
authors.forename: M I
authors.initials: MI
authors.lastname: Davis
authors.forename: P E
authors.initials: PE
authors.lastname: Spoerri
authors.forename: I
authors.initials: I
authors.lastname: Feoktistov
authors.forename: I
authors.initials: I
authors.lastname: Biaggioni
authors.forename: J C
authors.initials: JC
authors.lastname: Shryock
authors.forename: L
authors.initials: L
authors.lastname: Belardinelli
mesh_terms: D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media / Q000378:metabolism; D000242:Cyclic AMP / Q000235:genetics; D016228:Endothelial Growth Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000235:genetics; D005455:Fluorescent Antibody Technique; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D008222:Lymphokines / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D012171:Retinal Vessels / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D000906:Antibodies; D003470:Culture Media; D016228:Endothelial Growth Factors; D008222:Lymphokines; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D018047:Receptors, Purinergic P1; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D019830:Adenosine-5'-(N-ethylcarboxamide); D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP