title: Expression of the multidrug resistance proteins MRP2 and MRP3 in human cholangiocellular carcinomas.
abstract: BACKGROUND
  Cholangiocellular carcinomas and gallbladder carcinomas are highly aggressive tumours with a poor prognosis and are generally regarded as chemoresistant tumours. Overexpression of ATP-binding cassette transporters of the multidrug resistance protein (MDR) and multidrug resistance-related protein (MRP) family in cancer cells is a major cause for the multidrug resistance phenotype in vitro and in vivo. To further define the role of MRP family members in biliary tract cancer, we studied the expression and localization of MRP2 and MRP3 in cholangiocellular carcinomas and gallbladder carcinomas.
  
  
  METHODS
  The expression and cellular localization of the multidrug resistance proteins MRP2 and MRP3 in human cholangiocellular carcinomas and gallbladder carcinomas were analysed by immunohistochemistry using isoform-specific antibodies. Expression of MRP isoforms was studied in vitro in Mz-ChA-1 cells derived from gallbladder adenocarcinoma by reverse transcription-polymerase chain reaction (RT-PCR), immunoblotting and immunofluorescence microscopy.
  
  
  RESULTS
  Mz-ChA-1 cells constitutively expressed MDR P-glycoproteins, MRP1, MRP2 and MRP3 by RT-PCR, immunoblotting and immunofluorescence microscopy. MRP2 and MRP3 are expressed in the respective apical and basolateral membrane domains. MRP3 was the predominant MRP isoform in gallbladder carcinomas (93%) and cholangiocellular carcinomas (57%), whereas MRP2 expression was detected in only 29% of gallbladder carcinomas and was undetectable in cholangiocellular carcinomas.
  
  
  CONCLUSIONS
  Our findings suggest that the intrinsic multidrug resistance of cholangiocellular and gallbladder carcinomas seems to be independent of MRP2 expression while the expression of MRP3 may contribute to the MDR phenotype.
authors.affiliation: University of Heidelberg, Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Rau
authors.forename: F
authors.initials: F
authors.lastname: Autschbach
authors.forename: H D
authors.initials: HD
authors.lastname: Riedel
authors.forename: J
authors.initials: J
authors.lastname: Konig
authors.forename: H
authors.initials: H
authors.lastname: Kulaksiz
authors.forename: A
authors.initials: A
authors.lastname: Stiehl
authors.forename: J F
authors.initials: JF
authors.lastname: Riemann
authors.forename: D
authors.initials: D
authors.lastname: Rost
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018281:Cholangiocarcinoma / Q000235:genetics / Q000378:metabolism*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005706:Gallbladder Neoplasms / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D015151:Immunoblotting; D026901:Membrane Transport Proteins / Q000032:analysis* / Q000235:genetics; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000032:analysis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C000715087:ABCC2 protein, human; C114462:multidrug resistance-associated protein 3