title: Regulation of the multidrug resistance transporter P-glycoprotein in multicellular tumor spheroids by hypoxia-inducible factor (HIF-1) and reactive oxygen species.
abstract: Hypoxia in tumors is generally associated with chemoresistance and radioresistance. However, the correlation between the heterodimeric hypoxia-inducible factor-1 (HIF-1) and the multidrug resistance transporter P-glycoprotein (P-gp) has not been investigated. Herein, we demonstrate that with increasing size of DU-145 prostate multicellular tumor spheroids the pericellular oxygen pressure and the generation of reactive oxygen species decreased, whereas the alpha-subunit of HIF-1 (HIF-1alpha) and P-gp were up-regulated. Furthermore, P-gp was up-regulated under experimental physiological hypoxia and chemical hypoxia induced by either cobalt chloride or desferrioxamine. The pro-oxidants H2O2 and buthionine sulfoximine down-regulated HIF-1alpha and P-gp, whereas up-regulation was achieved with the radical scavengers dehydroascorbate, N-acetylcysteine, and vitamin E. The correlation of HIF-1alpha and P-gp expression was validated by the use of hepatoma tumor spheroids that were either wild type (Hepa1) or mutant (Hepa1C4) for aryl hydrocarbon receptor nuclear translocator (ARNT), i.e., HIF-1beta. Chemical hypoxia robustly increased HIF-1alpha as well as P-gp expression in Hepa1 tumor spheroids, whereas no changes were observed in Hepa1C4 spheroids. Hence, our data demonstrate that expression of P-gp in multicellular tumor spheroids is under the control of HIF-1.
authors.affiliation: Department of Neurophysiology, University of Cologne, D-50931 Cologne, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Wartenberg
authors.forename: Frederike C
authors.initials: FC
authors.lastname: Ling
authors.forename: Markus
authors.initials: M
authors.lastname: Müschen
authors.forename: Florian
authors.initials: F
authors.lastname: Klein
authors.forename: Helmut
authors.initials: H
authors.lastname: Acker
authors.forename: Max
authors.initials: M
authors.lastname: Gassmann
authors.forename: Kerstin
authors.initials: K
authors.lastname: Petrat
authors.forename: Volker
authors.initials: V
authors.lastname: Pütz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sauer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D015687:Cell Hypoxia; D004268:DNA-Binding Proteins; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008954:Models, Biological; D009154:Mutation; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018336:Receptors, Aryl Hydrocarbon; D018874:Spheroids, Cellular; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015854:Up-Regulation
chemical_list: C497396:ARNT protein, human; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D017382:Reactive Oxygen Species; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator