title: Metabolic markers in relation to hypoxia; staining patterns and colocalization of pimonidazole, HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4.
abstract: BACKGROUND
  The cellular response of malignant tumors to hypoxia is diverse. Several important endogenous metabolic markers are upregulated under hypoxic conditions. We examined the staining patterns and co-expression of HIF-1α, CAIX, LDH-5, GLUT-1, MCT1 and MCT4 with the exogenous hypoxic cell marker pimonidazole and the association of marker expression with clinicopathological characteristics.
  
  
  METHODS
  20 biopsies of advanced head and neck carcinomas were immunohistochemically stained and analyzed. All patients were given the hypoxia marker pimonidazole intravenously 2 h prior to biopsy taking. The tumor area positive for each marker, the colocalization of the different markers and the distribution of the markers in relation to the blood vessels were assessed by semiautomatic quantitative analysis.
  
  
  RESULTS
  MCT1 staining was present in hypoxic (pimonidazole stained) as well as non-hypoxic areas in almost equal amounts. MCT1 expression showed a significant overall correlation (r = 0.75, p < 0.001) and strong spatial relationship with CAIX. LDH-5 showed the strongest correlation with pimonidazole (r = 0.66, p = 0.002). MCT4 and GLUT-1 demonstrated a typical diffusion-limited hypoxic pattern and showed a high degree of colocalization. Both MCT4 and CAIX showed a higher expression in the primary tumor in node positive patients (p = 0.09 both).
  
  
  CONCLUSIONS
  Colocalization and staining patterns of metabolic and hypoxia-related proteins provides valuable additional information over single protein analyses and can improve the understanding of their functions and environmental influences.
authors.affiliation: Department of Radiation Oncology, Radboud University, Nijmegen Medical Centre, The Netherlands. s.rademakers@rther.umcn.nl
authors.forename: Saskia E
authors.initials: SE
authors.lastname: Rademakers
authors.forename: Jasper
authors.initials: J
authors.lastname: Lok
authors.forename: Albert J
authors.initials: AJ
authors.lastname: van der Kogel
authors.forename: Johan
authors.initials: J
authors.lastname: Bussink
authors.forename: Johannes H A M
authors.initials: JH
authors.lastname: Kaanders
mesh_terms: D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D015687:Cell Hypoxia; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000737:chemistry / Q000503:physiopathology*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D000080864:Lactate Dehydrogenase 5; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009367:Neoplasm Staging; D009389:Neovascularization, Pathologic / Q000503:physiopathology; D009593:Nitroimidazoles / Q000378:metabolism*; D015513:Oncogene Proteins / Q000378:metabolism; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D051272:Glucose Transporter Type 1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007527:Isoenzymes; C115081:MCTS1 protein, human; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D009593:Nitroimidazoles; D015513:Oncogene Proteins; D011506:Proteins; C406962:SLC16A4 protein, human; C033815:pimonidazole; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases