title: Role of the microtubule-targeting drug vinflunine on cell-cell adhesions in bladder epithelial tumour cells.
abstract: BACKGROUND
  Vinflunine (VFL) is a microtubule-targeting drug that suppresses microtubule dynamics, showing anti-metastatic properties both in vitro and in living cancer cells. An increasing body of evidence underlines the influence of the microtubules dynamics on the cadherin-dependent cell-cell adhesions. E-cadherin is a marker of epithelial-to-mesenchymal transition (EMT) and a tumour suppressor; its reduced levels in carcinoma are associated with poor prognosis. In this report, we investigate the role of VFL on cell-cell adhesions in bladder epithelial tumour cells.
  
  
  METHODS
  Human bladder epithelial tumour cell lines HT1376, 5637, SW780, T24 and UMUC3 were used to analyse cadherin-dependent cell-cell adhesions under VFL treatment. VFL effect on growth inhibition was measured by using a MTT colorimetric cell viability assay. Western blot, immunofluorescence and transmission electron microscopy analyses were performed to assess the roles of VFL effect on cell-cell adhesions, epithelial-to-mesenchymal markers and apoptosis. The role of the proteasome in controlling cell-cell adhesion was studied using the proteasome inhibitor MG132.
  
  
  RESULTS
  We show that VFL induces cell death in bladder cancer cells and activates epithelial differentiation of the remaining living cells, leading to an increase of E-cadherin-dependent cell-cell adhesion and a reduction of mesenchymal markers, such as N-cadherin or vimentin. Moreover, while E-cadherin is increased, the levels of Hakai, an E3 ubiquitin-ligase for E-cadherin, were significantly reduced in presence of VFL. In 5637, this reduction on Hakai expression was blocked by MG132 proteasome inhibitor, indicating that the proteasome pathway could be one of the molecular mechanisms involved in its degradation.
  
  
  CONCLUSIONS
  Our findings underscore a critical function for VFL in cell-cell adhesions of epithelial bladder tumour cells, suggesting a novel molecular mechanism by which VFL may impact upon EMT and metastasis.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Aparicio
authors.forename: Raquel
authors.initials: R
authors.lastname: Castosa
authors.forename: Mar
authors.initials: M
authors.lastname: Haz-Conde
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Moisés
authors.initials: M
authors.lastname: Blanco
authors.forename: Manuel
authors.initials: M
authors.lastname: Valladares
authors.affiliation: Translational Cancer Research Group, Instituto de Investigación Biomédica A Coruña (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC), Sergas, As Xubias, 15006 A Coruña, España. angelica.figueroa.conde-valvis@sergas.es.
authors.forename: Angélica
authors.initials: A
authors.lastname: Figueroa
mesh_terms: D017209:Apoptosis; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy / Q000473:pathology*; D014747:Vinblastine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: C111217:vinflunine; D014747:Vinblastine