title: Claudins and tricellulin in fibrolamellar hepatocellular carcinoma.
abstract: Fibrolamellar hepatocellular carcinoma is a subtype of hepatocellular carcinoma occurring in non-cirrhotic liver at a younger age. The tumor expresses both hepatocellular and cholangiocellular markers. Previously, our group described overexpression of tight junction protein claudin 4 in cholangiocellular carcinoma in contrast to hepatocellular carcinoma. In the present study, tight junction protein expressions were studied to possibly clarify bipotential lineage of fibrolamellar hepatocellular carcinoma. Eleven fibrolamellar hepatocellular carcinomas were compared with seven "conventional" hepatocellular carcinomas, seven cholangiocellular carcinomas, and five normal liver samples. By immunohistochemistry, all fibrolamellar hepatocellular carcinomas were positive for HepPar1 and cytokeratins 7, 8, and 18, but negative for cytokeratin 19. Glypican-3 gave weak staining in two cases. Expression of claudin 1 was lower, while that of claudin 2 was higher in fibrolamellar hepatocellular carcinomas than in other tumors. Claudins 3, 4, and 7 were not detectable in fibrolamellar hepatocellular carcinomas as in the majority of "conventional" hepatocellular carcinomas, contrary to high expression observed in cholangiocellular carcinomas. Focal or diffuse claudin 5 expression was detected in nine of 11 fibrolamellar hepatocellular carcinomas contrary to other tumors. Tricellulin was significantly downregulated in all tumors compared with normal liver. Our findings showed claudins to exhibit specific expression patterns in fibrolamellar hepatocellular carcinomas not observed in other primary liver tumors, with unique claudin 5 expression and pattern features similar to common hepatocellular carcinoma, but different from cholangiocellular carcinoma. This is the first report describing the loss of tricellulin expression in human hepatic tumors.
authors.affiliation: 2nd Department of Pathology, Semmelweis University, Üllői út 93, Budapest, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Patonai
authors.forename: Boglárka
authors.initials: B
authors.lastname: Erdélyi-Belle
authors.forename: Anna
authors.initials: A
authors.lastname: Korompay
authors.forename: Aron
authors.initials: A
authors.lastname: Somorácz
authors.forename: Beate K
authors.initials: BK
authors.lastname: Straub
authors.forename: Peter
authors.initials: P
authors.lastname: Schirmacher
authors.forename: Ilona
authors.initials: I
authors.lastname: Kovalszky
authors.forename: Gábor
authors.initials: G
authors.lastname: Lotz
authors.forename: András
authors.initials: A
authors.lastname: Kiss
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Schaff
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002648:Child; D018281:Cholangiocarcinoma / Q000378:metabolism / Q000473:pathology; D057167:Claudins / Q000378:metabolism*; D005260:Female; D053673:Glypicans / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D062794:MARVEL Domain Containing 2 Protein; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D057167:Claudins; D053673:Glypicans; D062794:MARVEL Domain Containing 2 Protein; C516798:MARVELD2 protein, human; D008565:Membrane Proteins; D007633:Keratins