title: Selective inhibition of MEK1/2 reveals a differential requirement for ERK1/2 signalling in the regulation of HIF-1 in response to hypoxia and IGF-1.
abstract: The transcription factor hypoxia-inducible factor 1 (HIF-1) plays a pivotal role in tumour growth and progression, and HIF-1 is regulated through a number of signalling pathways. Here, we investigated the involvement of the mitogen-activated protein kinase (MAPK) signalling pathway in HIF-1 regulation. We found that overexpression of wild-type (WT) extracellular signal regulated protein kinase 1 (ERK1) greatly potentiated HIF-1 activation in hypoxia and HIF-1alpha induced in response to insulin growth-like factor 1 (IGF-1). Conversely, treatment of tumour cells with the MEK1/2 inhibitors PD98059 or U0216, or expression of a dominant-negative form of ERK1 blocked HIF-1 activation in hypoxia without affecting HIF-1alpha induction, localization or binding of HIF-1beta. Interestingly however, the highly selective MEK1/2 inhibitor PD184352 did not inhibit HIF-1 activity or vascular endothelial growth factor (VEGF) induced in response to hypoxia but blocked HIF-1alpha protein and HIF-1 activity induced by IGF-1 stimulation without affecting HIF-1alpha mRNA levels. Finally, we found that ERK5 phosphorylation status was not significantly affected by hypoxia in the presence or absence of PD184352. Taken together, our data suggest that although ERK1/2 signalling is important for HIF-1alpha induction and HIF-1 activity in response to IGF-1, it is dispensable for the induction of HIF-1alpha and activation of HIF-1 in response to hypoxia.
authors.affiliation: Cell Growth Regulation and Angiogenesis Team, Cancer Research UK Centre for Cancer Therapeutics, The Institute of Cancer Research, Sutton, Surrey, UK.
authors.forename: K M
authors.initials: KM
authors.lastname: Sutton
authors.forename: S
authors.initials: S
authors.lastname: Hayat
authors.forename: N-M
authors.initials: NM
authors.lastname: Chau
authors.forename: S
authors.initials: S
authors.lastname: Cook
authors.forename: J
authors.initials: J
authors.lastname: Pouyssegur
authors.forename: A
authors.initials: A
authors.lastname: Ahmed
authors.forename: N
authors.initials: N
authors.lastname: Perusinghe
authors.forename: R
authors.initials: R
authors.lastname: Le Floch
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: M
authors.initials: M
authors.lastname: Ashcroft
mesh_terms: D001549:Benzamides / Q000494:pharmacology; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014162:Transfection
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D001549:Benzamides; D002070:Butadienes; D005419:Flavonoids; D051793:Hypoxia-Inducible Factor 1; D009570:Nitriles; D011993:Recombinant Fusion Proteins; C113580:U 0126; D007334:Insulin-Like Growth Factor I; D008156:Luciferases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one