title: Hydrogen peroxide signaling mediates DHEA-induced vascular endothelial cell proliferation.
abstract: Dehydroepiandrosterone (DHEA) activates a putative plasma membrane G(i)-protein coupled receptor to induce vascular endothelial proliferation. We now test the hypothesis that hydrogen peroxide (H(2)O(2)) signaling mediates this effect. Incubation of EA.hy926 cells, a human vascular endothelial cell line, with DHEA for 5 min produced a significant increase in H(2)O(2) production, measured by oxidation of either p-hydroxyphenylacetate or dichlorodihydrofluorescein. The DHEA effect on H(2)O(2) production was maximal at 1 nM DHEA, was evident within the first minute of incubation, and remained for 10 min. Similar results were present in primary bovine aortic endothelial cells. The induction of H(2)O(2) in EA.hy926 cells was mimicked by a membrane-impermeable albumin-conjugated DHEA and was inhibited by either catalase or pertussis toxin. Incubation of endothelial cells with DHEA for 5 min resulted in a 2-fold increase of cyclin D1 mRNA and protein expression at 4h. These effects were abolished by co-incubation with catalase. DHEA induced a 50 ± 7% increase in cell proliferation over 24h, measured as cellular Ki-67 immunoreactivity. This proliferative effect was abolished by either catalase or pertussis toxin co-incubation, indicating an H(2)O(2) and G(i)-protein-dependent effect. We conclude that H(2)O(2) is a key signaling molecule mediating the proliferative effects of DHEA in vascular endothelial cells, possibly by up-regulating cell-cycle associated genes, such as cyclin D1.
authors.affiliation: Research Service, Veterans Administration Medical Center, and Division of Endocrinology, Department of Internal Medicine, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52246, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Iruthayanathan
authors.forename: Brianne
authors.initials: B
authors.lastname: O'Leary
authors.forename: Gautam
authors.initials: G
authors.lastname: Paul
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Dillon
mesh_terms: D000818:Animals; D002417:Cattle; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000235:genetics; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D019938:Cyclin D1; D003687:Dehydroepiandrosterone; D006861:Hydrogen Peroxide; D019204:GTP-Binding Proteins