title: Aquaporin 3 (AQP3) participates in the cytotoxic response to nucleoside-derived drugs.
abstract: BACKGROUND
  Nucleoside analogs used in the chemotherapy of solid tumors, such as the capecitabine catabolite 5'-deoxy-5-fluorouridine (5'-DFUR) trigger a transcriptomic response that involves the aquaglyceroporin aquaporin 3 along with other p53-dependent genes. Here, we examined whether up-regulation of aquaporin 3 (AQP3) mRNA in cancer cells treated with 5'-DFUR represents a collateral transcriptomic effect of the drug, or conversely, AQP3 participates in the activity of genotoxic agents.
  
  
  METHODS
  The role of AQP3 in cell volume increase, cytotoxicity and cell cycle arrest was analyzed using loss-of-function approaches.
  
  
  RESULTS
  5'-DFUR and gemcitabine, but not cisplatin, stimulated AQP3 expression and cell volume, which was partially and significantly blocked by knockdown of AQP3. Moreover, AQP3 siRNA significantly blocked other effects of nucleoside analogs, including G1/S cell cycle arrest, p21 and FAS up-regulation, and cell growth inhibition. Short incubations with 5-fluorouracil (5-FU) also induced AQP3 expression and increased cell volume, and the inhibition of AQP3 expression significantly blocked growth inhibition triggered by this drug. To further establish whether AQP3 induction is related to cell cycle arrest and apoptosis, cells were exposed to long incubations with escalating doses of 5-FU. AQP3 was highly up-regulated at doses associated with cell cycle arrest, whereas at doses promoting apoptosis induction of AQP3 mRNA expression was reduced.
  
  
  CONCLUSIONS
  Based on the results, we propose that the aquaglyceroporin AQP3 is required for cytotoxic activity of 5'-DFUR and gemcitabine in the breast cancer cell line MCF7 and the colon adenocarcinoma cell line HT29, and is implicated in cell volume increase and cell cycle arrest.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina de la Universitat de Barcelona, Universitat de Barcelona, and Centro de Investigación Biomédica en Red - Enfermedades Hepáticas y Digestivas, Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Laia
authors.initials: L
authors.lastname: Trigueros-Motos
authors.forename: Sandra
authors.initials: S
authors.lastname: Pérez-Torras
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Casado
authors.forename: Míriam
authors.initials: M
authors.lastname: Molina-Arcas
authors.forename: Marçal
authors.initials: M
authors.lastname: Pastor-Anglada
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D051400:Aquaporin 3 / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D059447:Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D048429:Cell Size / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005467:Floxuridine / Q000494:pharmacology; D005472:Fluorouracil / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D019073:HT29 Cells; D006801:Humans; D061986:MCF-7 Cells; D009705:Nucleosides / Q000737:chemistry / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism; D000093542:Gemcitabine
chemical_list: D000970:Antineoplastic Agents; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009705:Nucleosides; D019014:fas Receptor; D005467:Floxuridine; D003841:Deoxycytidine; D051400:Aquaporin 3; D005472:Fluorouracil; C025034:doxifluridine; D000093542:Gemcitabine