title: Glycolytic pyruvate regulates P-Glycoprotein expression in multicellular tumor spheroids via modulation of the intracellular redox state.
abstract: ABC transporters like P-glycoprotein (P-gp/ABCB1) are membrane proteins responsible for the transport of toxic compounds out of non-malignant cells and tumor tissue.
  
  
  OBJECTIVE
  To investigate the effect of glycolysis and the tissue redox state on P-gp expression in multicellular tumor spheroids derived from prostate adenocarcinoma cells (DU-145), glioma cells (Gli36), and the human cervix carcinoma cell line KB-3-1 transfected with a P-gp-EGFP fusion gene that allows monitoring of P-gp expression in living cells. During cell culture of DU-145, Gli36, and KB-3-1 tumor spheroids P-gp expression was observed as well as increased lactate and decreased pyruvate levels and expression of glycolytic enzymes. Inhibition of glycolysis for 24 h by either iodoacetate (IA) or 2-deoxy-D-glucose (2-DDG) downregulated P-gp expression which was reversed upon coincubation with the radical scavenger ebselen as shown by semi-quantitative immunohistochemisty in DU-145 and Gli36 tumor spheroids, and by EGFP fluorescence in KB-3-1 tumor spheroids. Consequently endogenous ROS generation in DU-145 tumor spheroids was increased in the presence of either IA or 2-DDG, which was abolished upon coincubation with ebselen. Exogenous addition of pyruvate significantly reduced ROS generation, increased P-gp expression as well as efflux of the P-gp substrate doxorubicin. Doxorubicin transport was significantly blunted by 2-DDG and IA, indicating that inhibition of glycolysis reversed the multidrug resistance phenotype. In summary our data demonstrate that P-gp expression in tumor spheroids is closely related to the glycolytic metabolism of tumor cells and can be downregulated by glycolysis inhibitors via mechanisms that involve changes in the cellular redox state.
authors: Department of Internal Medicine I, Cardiology Division, Friedrich Schiller University, Jena, Germany.
authors: Maria
authors: M
authors: Wartenberg
authors: Madeleine
authors: M
authors: Richter
authors: André
authors: A
authors: Datchev
authors: Sebastian
authors: S
authors: Günther
authors: Nada
authors: N
authors: Milosevic
authors: Mohamed M
authors: MM
authors: Bekhite
authors: Hans-Reiner
authors: HR
authors: Figulla
authors: Josep M
authors: JM
authors: Aran
authors: Jordi
authors: J
authors: Pétriz
authors: Heinrich
authors: H
authors: Sauer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology; D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics; D001693:Biological Transport, Active / Q000187:drug effects*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000493:pharmacokinetics; D018432:Drug Resistance, Multiple / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D006019:Glycolysis; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D019289:Pyruvic Acid / Q000378:metabolism* / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000378:metabolism*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D017382:Reactive Oxygen Species; D019344:Lactic Acid; D004317:Doxorubicin; D019289:Pyruvic Acid