title: Tumor microenvironmental changes induced by the sulfamate carbonic anhydrase IX inhibitor S4 in a laryngeal tumor model.
abstract: OBJECTIVE
  Carbonic anhydrase IX (CAIX) plays a pivotal role in pH homeostasis, which is essential for tumor cell survival. We examined the effect of the CAIX inhibitor 4-(3'(3",5"-dimethylphenyl)-ureido)phenyl sulfamate (S4) on the tumor microenvironment in a laryngeal tumor model by analyzing proliferation, apoptosis, necrosis, hypoxia, metabolism and CAIX ectodomain shedding.
  
  
  METHODS
  SCCNij202 tumor bearing-mice were treated with S4 for 1, 3 or 5 days. CAIX ectodomain shedding was measured in the serum after therapy. Effects on tumor cell proliferation, apoptosis, necrosis, hypoxia (pimonidazole) and CAIX were investigated with quantitative immunohistochemistry. Metabolic transporters and enzymes were quantified with qPCR.
  
  
  RESULTS
  CAIX ectodomain shedding decreased after treatment with S4 (p<0.01). S4 therapy did neither influence tumor cell proliferation nor the amount of apoptosis and necrosis. Hypoxia (pimonidazole) and CAIX expression were also not affected by S4. CHOP and MMP9 mRNA as a reference of intracellular pH did not change upon treatment with S4. Compensatory mechanisms of pH homeostasis at the mRNA level were not observed.
  
  
  CONCLUSIONS
  As the clinical and biological meaning of the decrease in CAIX ectodomain shedding after S4 therapy is not clear, studies are required to elucidate whether the CAIX ectodomain has a paracrine or autocrine signaling function in cancer biology. S4 did not influence the amount of proliferation, apoptosis, necrosis and hypoxia. Therefore, it is unlikely that S4 can be used as single agent to influence tumor cell kill and proliferation, and to target primary tumor growth.
authors.affiliation: Department of Radiation Oncology, 874 Radboud university medical center, HB Nijmegen, The Netherlands.
authors.forename: Tineke W H
authors.initials: TW
authors.lastname: Meijer
authors.affiliation: Department of Radiation Oncology, 874 Radboud university medical center, HB Nijmegen, The Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: Bussink
authors.affiliation: Department of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
authors.forename: Miriam
authors.initials: M
authors.lastname: Zatovicova
authors.affiliation: Department of Radiation Oncology, 874 Radboud university medical center, HB Nijmegen, The Netherlands.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Span
authors.affiliation: Department of Radiation Oncology, 874 Radboud university medical center, HB Nijmegen, The Netherlands.
authors.forename: Jasper
authors.initials: J
authors.lastname: Lok
authors.affiliation: Laboratorio di Chimica Bioinorganica, Polo Scientifico, Università degli Studi di Firenze, Sesto Fiorentino, Florence, Italy.
authors.forename: Claudiu T
authors.initials: CT
authors.lastname: Supuran
authors.affiliation: Department of Radiation Oncology, 874 Radboud university medical center, HB Nijmegen, The Netherlands.
authors.forename: Johannes H A M
authors.initials: JH
authors.lastname: Kaanders
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D030741:Carbonic Anhydrase IV / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007822:Laryngeal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D047368:Tumor Burden / Q000187:drug effects; D059016:Tumor Microenvironment / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D030741:Carbonic Anhydrase IV