title: Expression of organic anion-transporting polypeptides 1B3, 1B1, and 1A2 in human pancreatic cancer reveals a new class of potential therapeutic targets.
abstract: BACKGROUND
  Organic anion-transporting polypeptides (OATPs) are influx transporters that mediate intracellular uptake of selective endogenous and xenobiotic compounds. Identification of new molecular targets and discovery of novel targeted therapies is top priority for pancreatic cancer, which lacks any effective therapy.
  
  
  METHODS
  We studied expression of OATP 1A2, 1B1, and 1B3 in pancreatic cancer tissue and in cell lines. Formalin-fixed paraffin-embedded biopsy material of 12 human pancreatic cancers was immunohistochemically assessed for protein expression of the three studied influx transporters. Immunohistochemistry was evaluated by experienced pathologists and quantified by use of an automated image analysis system. BxPC-3 and MIA PaCa-2 pancreatic cancer cell lines were used to quantify transcripts of OATP 1B1 and 1B3.
  
  
  RESULTS
  OATP 1A2, 1B1, and 1B3 proteins were found ubiquitously expressed in all studied cases. Quantification performed by HistoQuest system revealed that mean intensity was 53 for 1A2, 45 for 1B1, and 167 for OATP 1B1/1B3 on a range scale 0-250 units. At mRNA level, 1B1 and 1B3 were overexpressed in both studied cancer cell lines but not in normal pancreatic tissue.
  
  
  CONCLUSIONS
  OATPs 1A2, 1B1, and 1B3 are highly expressed in pancreatic adenocarcinoma. We suggest that expression of these transporters in pancreatic cancer justify research efforts towards discovery of novel therapeutics targeting OATPs.
authors.affiliation: Cancer Biobank Center of the University of Ioannina, Greece;
authors.forename: Valentinos
authors.initials: V
authors.lastname: Kounnis
authors.forename: Elli
authors.initials: E
authors.lastname: Ioachim
authors.forename: Martin
authors.initials: M
authors.lastname: Svoboda
authors.forename: Andreas
authors.initials: A
authors.lastname: Tzakos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Sainis
authors.forename: Theresia
authors.initials: T
authors.lastname: Thalhammer
authors.forename: Georg
authors.initials: G
authors.lastname: Steiner
authors.forename: Evangelos
authors.initials: E
authors.lastname: Briasoulis