title: Effect of ascorbate on the activity of hypoxia-inducible factor in cancer cells.
abstract: Hypoxia-inducible factor (HIF) plays an important role in determining patterns of gene expression in cancer. HIF is down-regulated in oxygenated cells by a series of Fe (II) and 2-oxoglutarate dependent dioxygenases that hydroxylate specific residues in the regulatory HIF-alpha subunits. Because these enzymes require ascorbate for activity in vitro we analyzed the effects of ascorbate on HIF in human cancer cell lines. Ascorbate at physiological concentrations (25 micro M) strikingly suppressed HIF-1alpha protein levels and HIF transcriptional targets, particularly when the system was oncogenically activated in normoxic cells. Similar results were obtained with iron supplementation. These results indicate that both ascorbate and iron availability have major effects on HIF, and imply that the system is commonly regulated by limiting hydroxylase activity under normoxic tissue culture conditions.
authors.affiliation: Cancer Research United Kingdom Molecular Oncology Laboratory, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS.
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Knowles
authors.forename: Raju R
authors.initials: RR
authors.lastname: Raval
authors.forename: Adrian L
authors.initials: AL
authors.lastname: Harris
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ratcliffe
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology; D016228:Endothelial Growth Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D005260:Female; D005296:Ferrous Compounds / Q000494:pharmacology; D051272:Glucose Transporter Type 1; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D008222:Lymphokines / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000235:genetics; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000378:metabolism; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D014168:Transferrin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D016228:Endothelial Growth Factors; D005296:Ferrous Compounds; D051272:Glucose Transporter Type 1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495677:SLC2A1 protein, human; D014157:Transcription Factors; D014168:Transferrin; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D011393:Procollagen-Proline Dioxygenase; D001205:Ascorbic Acid; C029451:ferrous chloride