title: ATP-binding cassette C transporters in human pancreatic carcinoma cell lines. Upregulation in 5-fluorouracil-resistant cells.
abstract: BACKGROUND
  Pancreatic cancer is characterized by high resistance to chemotherapy. Such chemoresistance can be mediated by multidrug resistance proteins (MRPs), breast cancer resistance protein (BCRP), and MDR1 P-glycoprotein. However, the contribution of individual MRP isoforms to chemoresistance in pancreatic carcinoma is unclear. We studied ATP-binding cassette (ABC) transporter expression in human pancreatic carcinoma cell lines as compared to primary pancreatic duct cells, and analyzed the MRP expression profile in 5-fluorouracil-resistant cells.
  
  
  METHODS
  Transporter expression was analyzed by quantitative and qualitative RT-PCR, by immunoblot, and chemoresistance by cytotoxicity assay.
  
  
  RESULTS
  Primary pancreatic duct cells expressed MRP1, MRP3, MRP4, and MRP5, but not MRP2 mRNA. The established carcinoma cell lines expressed MRP1, MRP4, and MRP5, most of them also MRP2, MRP3, MRP7, and BCRP, but none contained detectable amounts of MRP6, MRP8, or MRP9 mRNA. Immunoblot analyses demonstrated presence of MRP1, MRP4, and MRP5 protein in all, but MRP3 and BCRP protein only in some of these cells. Compared to parental Capan-1 cells, Capan-1 cells with acquired chemoresistance towards 5-fluorouracil showed an upregulated mRNA and protein expression of MRP3, MRP4, and MRP5. In addition, silencing of MRP5 by RNA interference resulted in enhanced sensitivity of parental Capan-1 cells towards 5-fluorouracil cytotoxicity.
  
  
  CONCLUSIONS
  MRP3, MRP4, and MRP5 are upregulated in 5-fluorouracil-resistant cells, and MRP5 contributes to 5-FU resistance in pancreatic carcinoma cells.
authors.affiliation: Clinical Cooperation Unit of Molecular Gastroenterology, German Cancer Research Center, Heidelberg, Germany. w.hagmann@dkfz.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hagmann
authors.forename: Ralf
authors.initials: R
authors.lastname: Jesnowski
authors.forename: Ralf
authors.initials: R
authors.lastname: Faissner
authors.forename: Changqing
authors.initials: C
authors.lastname: Guo
authors.forename: J Matthias
authors.initials: JM
authors.lastname: Löhr
mesh_terms: D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005472:Fluorouracil / Q000494:pharmacology*; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis*; D010190:Pancreatic Neoplasms / Q000235:genetics*; D034622:RNA Interference; D015854:Up-Regulation
chemical_list: D005472:Fluorouracil; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C073492:ABCC4 protein, human; C120809:ABCC5 protein, human; C114462:multidrug resistance-associated protein 3; C421109:multidrug resistance-associated protein 1