title: Claudin-7 protein differentiates canine cholangiocarcinoma from hepatocellular carcinoma.
abstract: The aim of the present study was to characterise the expression pattern of claudin-7 tight junction protein in canine normal liver, hyperplastic and primary neoplastic lesions of the canine liver and whether this tight junction protein can help differentiate canine cholangiocarcinomas from canine hepatocellular carcinomas.
  
  
  
  Necropsy samples included 15 canine normal liver tissue samples, 10 hepatocellular nodular hyperplasias, 6 hepatocellular adenomas, 15 well-differentiated and 6 poorly differentiated hepatocellular carcinomas, 6 cholangiocellular hyperplasias, 10 cholangiocellular adenomas, 15 well-differentiated and 6 poorly differentiated cholangiocarcinomas, 6 normal extrahepatic bile ducts, 8 normal gall bladder tissue samples, and 5 cystic mucinous hyperplasias of the gall bladder. In all canine normal liver tissue samples the hepatocytes were negative for claudin-7 and the normal biliary epithelial cells showed intense basolateral membrane claudin-7 positivity. In all cholangiocellular hyperplasia samples and in all cholangiocellular adenoma samples the benign cholangiocytes showed intense basolateral membrane positivity for claudin-7. In all samples of the well-differentiated and poorly differentiated cholangiocarcinomas, the malignant neoplastic biliary epithelial cells showed intense basolateral membrane positivity for claudin-7. Neither the hyperplastic nodules of the liver cells nor the hepatocellular adenomas reacted with claudin-7. The well-differentiated and poorly differentiated hepatocellular cancers were negative for claudin-7. The epithelial cells of canine normal extrahepatic bile ducts, gall bladder and cystic mucinous hyperplasias of the gall bladder showed intense basolateral membrane positivity for claudin-7. Differences in the intensity of claudin-7 reaction were not apparent among different types of proliferative lesions of cholangiocytes or degrees of cellular differentiation of neoplastic biliary epithelial cells.
  
  
  
  Consequently, we hypothesize that claudin-7 is an excellent immunohistochemical marker of the cholangiocellular differentiation in canines and can be used to detect benign and malignant proliferative lesions of the canine biliary tract. It can also help to differentiate canine cholangiocarcinomas from hepatocellular carcinomas.
authors.affiliation: Szent István University, Faculty of Veterinary Science, Department of Pathology and Forensic Veterinary Medicine, Budapest, Hungary. jakab.csaba@aotk.szie.hu
authors.forename: Cs
authors.initials: C
authors.lastname: Jakab
authors.forename: A
authors.initials: A
authors.lastname: Kiss
authors.forename: Zs
authors.initials: Z
authors.lastname: Schaff
authors.forename: Z
authors.initials: Z
authors.lastname: Szabó
authors.forename: M
authors.initials: M
authors.lastname: Rusvai
authors.forename: P
authors.initials: P
authors.lastname: Gálfi
authors.forename: A
authors.initials: A
authors.lastname: Szabára
authors.forename: A
authors.initials: A
authors.lastname: Sterczer
authors.forename: J
authors.initials: J
authors.lastname: Kulka
mesh_terms: D018248:Adenoma, Liver Cell / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001659:Biliary Tract / Q000378:metabolism / Q000473:pathology; D001661:Biliary Tract Neoplasms / Q000378:metabolism / Q000473:pathology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D018281:Cholangiocarcinoma / Q000378:metabolism / Q000473:pathology; D057167:Claudins; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D011506:Proteins / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism / Q000473:pathology
chemical_list: D057167:Claudins; D011506:Proteins