title: Hypoxia enhances FGF2- and VEGF-stimulated human placental artery endothelial cell proliferation: roles of MEK1/2/ERK1/2 and PI3K/AKT1 pathways.
abstract: Placental development occurs under a low oxygen (2-8% O(2)) environment, which is critical for placental development and angiogenesis. In this study, we examined if hypoxia affected fibroblast growth factor-2 (FGF2)- and vascular endothelial growth factor (VEGF)-stimulated cell proliferation via the mitogen-activated protein kinase kinase 1/2 (MEK1/2)/extracellular signal-regulated kinases 1/2 (ERK1/2) and phosphatidylinositol-3 kinase (PI3K)/v-akt murine thymomaviral oncogene homologue (AKT1) pathways in human placental artery endothelial (HPAE) cells. We observed that under normoxia (approximately 20% O(2)), FGF2 and VEGF dose-dependently stimulated cell proliferation. Hypoxia (3% O(2)) significantly promoted FGF2- and VEGF-stimulated cell proliferation as compared to normoxia. Under both normoxia and hypoxia, FGF2 rapidly induced ERK1/2 and AKT1 phosphorylation, while VEGF-induced ERK1/2, but not AKT1 phosphorylation. However, hypoxia did not significantly alter FGF2- and VEGF-induced ERK1/2 and AKT1 phosphorylation as compared to normoxia. PD98059 (a MEK1/2 inhibitor) at 20microM and LY294002 (a PI3K inhibitor) at 5microM attenuated FGF2- and VEGF-induced phosphorylation of ERK1/2 and AKT1, respectively. PD98059, even at doses that drastically inhibited FGF2-induced ERK1/2 phosphorylation (20microM) and caused cell loss (40microM), did not affect FGF2-stimulated cell proliferation, which was confirmed by U0126 (another potent MEK1/2 inhibitor). PD98059, however, dose-dependently inhibited VEGF-stimulated cell proliferation. Conversely, LY294002 dose-dependently inhibited FGF2-, but not VEGF-stimulated cell proliferation. These data suggest that in the MEK1/2/ERK1/2 and PI3K/AKT1 pathways differentially mediate FGF2- and VEGF-stimulated HPAE cell proliferation. These results also indicate that hypoxia promotes FGF2- and VEGF-stimulated cell proliferation without further activation of the PI3K/AKT1 and MEK1/2/ERK1/2, respectively.
authors.affiliation: Department of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, Madison, WI 53715, USA.
authors.forename: K
authors.initials: K
authors.lastname: Wang
authors.forename: Y-z
authors.initials: YZ
authors.lastname: Jiang
authors.forename: D-b
authors.initials: DB
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Zheng
mesh_terms: D001158:Arteries / Q000166:cytology; D002070:Butadienes / Q000494:pharmacology; D015687:Cell Hypoxia / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D002070:Butadienes; D002867:Chromones; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D005419:Flavonoids; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009025:Morpholines; D009570:Nitriles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; C113580:U 0126; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C482128:MAP2K2 protein, human; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one