title: Methotrexate modulates tight junctions through NF-κB, MEK, and JNK pathways.
abstract: OBJECTIVE
  Chemotherapy often induces intestinal mucositis, which is associated with an increase in intestinal permeability; however, underlying mechanisms remain incompletely understood. Thus, we aimed to study the regulation of 3 tight junction (TJ) proteins, claudin-1, occludin, and zonula occludens-1, after anticancer treatment.
  
  
  METHODS
  Methotrexate (MTX) was subcutaneously injected for 3 consecutive days in Sprague-Dawley rats to induce intestinal mucositis and was applied on Caco-2 cell monolayers. TJ protein expression and cellular distribution were studied by Western blot and microscopy, respectively. In Caco-2 cells, the paracellular permeability was evaluated by both transepithelial electrical resistance and flux of fluorescein isothiocyanate-dextran marker. Cytokine production and signaling pathways were also assessed.
  
  
  RESULTS
  In MTX-treated rats, the cellular distribution of the 3 TJ proteins was altered and claudin-1 and occludin expression was reduced during the acute phase of mucositis compared with controls. During the recovery phase, these parameters were restored. In vitro, MTX treatment led to an increase in proinflammatory cytokine production at the apical side but did not affect Caco-2 cell apoptosis and necrosis. Increase in paracellular permeability was associated with altered occludin and zonula occludens-1 expression and cellular distribution. All of these alterations were prevented by MEK1 and 2, JNK, and NF-κB inhibitors.
  
  
  CONCLUSIONS
  MTX treatment induced an increase in intestinal permeability partially related to alteration of TJs protein expression and cellular distribution that may be mediated by MAPK and NF-κB pathways. These are potential targets to limit the adverse effects of chemotherapy.
authors.affiliation: INSERM U1073, Institute for Biomedical Research, IFRMP23, Rouen University, 22 Boulevard Gambetta, Rouen Cedex 1, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Beutheu Youmba
authors.forename: Liliana
authors.initials: L
authors.lastname: Belmonte
authors.forename: Ludovic
authors.initials: L
authors.lastname: Galas
authors.forename: Nabile
authors.initials: N
authors.lastname: Boukhettala
authors.forename: Christine
authors.initials: C
authors.lastname: Bôle-Feysot
authors.forename: Pierre
authors.initials: P
authors.lastname: Déchelotte
authors.forename: Moïse
authors.initials: M
authors.lastname: Coëffier
mesh_terms: D000818:Animals; D017209:Apoptosis; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects; D062445:Claudin-1; D003911:Dextrans; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008727:Methotrexate / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D062793:Occludin; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism
chemical_list: C568108:CLDN1 protein, human; D062445:Claudin-1; C568114:Cldn1 protein, rat; D003911:Dextrans; D008565:Membrane Proteins; D016328:NF-kappa B; C568985:OCLN protein, human; D062793:Occludin; C568987:Ocln protein, rat; C015219:fluorescein isothiocyanate dextran; C482128:MAP2K2 protein, human; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D016650:Fluorescein-5-isothiocyanate; D008727:Methotrexate