title: Multidrug resistance protein 1 localization in lipid raft domains and prostasomes in prostate cancer cell lines.
abstract: BACKGROUND
  One of the problems in prostate cancer (CaP) treatment is the appearance of the multidrug resistance phenotype, in which ATP-binding cassette transporters such as multidrug resistance protein 1 (MRP1) play a role. Different localizations of the transporter have been reported, some of them related to the chemoresistant phenotype.
  
  
  OBJECTIVE
  This study aimed to compare the localization of MRP1 in three prostate cell lines (normal, androgen-sensitive, and androgen-independent) in order to understand its possible role in CaP chemoresistance.
  
  
  METHODS
  MRP1 and caveolae protein markers were detected using confocal microscopy, performing colocalization techniques. Lipid raft isolation made it possible to detect these proteins by Western blot analysis. Caveolae and prostasomes were identified by electron microscopy.
  
  
  RESULTS
  We show that MRP1 is found in lipid raft fractions of tumor cells and that the number of caveolae increases with malignancy acquisition. MRP1 is found not only in the plasma membrane associated with lipid rafts but also in cytoplasmic accumulations colocalizing with the prostasome markers Caveolin-1 and CD59, suggesting that in CaP cells, MRP1 is localized in prostasomes.
  
  
  CONCLUSIONS
  We hypothesize that the presence of MRP1 in prostasomes could serve as a reservoir of MRP1; thus, taking advantage of the release of their content, MRP1 could be translocated to the plasma membrane contributing to the chemoresistant phenotype. The presence of MRP1 in prostasomes could serve as a predictor of malignancy in CaP.
authors.affiliation: Departament de Ciències Fisiològiques II, Faculty of Medicine, Campus of Health Sciences of Bellvitge, Universitat de Barcelona, IDIBELL, Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Gomà
authors.affiliation: Departament de Ciències Fisiològiques II, Faculty of Medicine, Campus of Health Sciences of Bellvitge, Universitat de Barcelona, IDIBELL, Barcelona, Spain ; División de Investigación Básica, Instituto Nacional de Cancerología, México DF, Mexico ; Instituto de Física, Universidad Nacional Autónoma de México (UNAM), México DF, Mexico.
authors.forename: Roser
authors.initials: R
authors.lastname: Mir
authors.affiliation: Departament de Ciències Fisiològiques II, Faculty of Medicine, Campus of Health Sciences of Bellvitge, Universitat de Barcelona, IDIBELL, Barcelona, Spain ; Department of Basic Nursing, School of Nursing of the Health Campus of Bellvitge, Universitat de Barcelona, Spain.
authors.forename: Fina
authors.initials: F
authors.lastname: Martínez-Soler
authors.affiliation: Department of Basic Nursing, School of Nursing of the Health Campus of Bellvitge, Universitat de Barcelona, Spain.
authors.forename: Avelina
authors.initials: A
authors.lastname: Tortosa
authors.affiliation: Department of Pathology, Hospital Universitari de Bellvitge, IDIBELL, Barcelona, Spain ; Department of Pathology and Experimental Therapeutics, Universitat de Barcelona, IDIBELL, Barcelona, Spain.
authors.forename: August
authors.initials: A
authors.lastname: Vidal
authors.affiliation: Department of Pathology, Hospital Universitari de Bellvitge, IDIBELL, Barcelona, Spain ; Department of Pathology and Experimental Therapeutics, Universitat de Barcelona, IDIBELL, Barcelona, Spain.
authors.forename: Enric
authors.initials: E
authors.lastname: Condom
authors.affiliation: Department of Pathology and Experimental Therapeutics, Universitat de Barcelona, IDIBELL, Barcelona, Spain.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pérez-Tomás
authors.affiliation: Departament de Ciències Fisiològiques II, Faculty of Medicine, Campus of Health Sciences of Bellvitge, Universitat de Barcelona, IDIBELL, Barcelona, Spain.
authors.forename: Pepita
authors.initials: P
authors.lastname: Giménez-Bonafé
keywords: Caveolin-1; MRP1; caveolae; lipid rafts; prostasomes; prostate cancer