title: Altered expression of beta-catenin without genetic mutation in intrahepatic cholangiocarcinoma.
abstract: beta-catenin which has a role in E-cadherin mediated cell-to-cell adhesion, and is also involved in Wnt signaling pathways as a downstream signaling molecule accumulating in the cytoplasm and nucleus constitutively activates Tcf/LEF-associated transcription of oncogenic genes. We examined the expression pattern and the genetic alteration of beta-catenin to determine the role of beta-catenin in cancer formation and/or progression in intrahepatic cholangiocarcinoma (ICC). beta-catenin expression was immunohistochemically examined in 71 surgically resected ICC samples, and correlation between the expression pattern and clinicopathologic factors was investigated. Mutation analysis of beta-catenin exon 3, which included the responsible element for Wnt signaling was done in 55 samples, using PCR-SSCP and direct sequence methods. Immunohistochemical analysis revealed the reduced membranous expression of beta-catenin in 58 (82%) ICCs and aberrant nuclear expression in 11 (15%) ICCs. The membranous expression was preserved in 62% of the papillary adenocarcinomas, and was frequently reduced in tumors with a poorer histological differentiation (84%), with a significant difference (P =.01). Genetic analysis showed that none of the 55 ICCs examined carried mutations in beta-catenin exon 3. The present study indicates that reduced membranous expression of beta-catenin is associated with non-papillary ICCs which have a more malignant behavior, and that nuclear translocation of beta-catenin results in oncogenic events. Mutations in beta-catenin exon 3 do not appear to be responsible for nuclear translocation of beta-catenin in ICCs.
authors.affiliation: Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sugimachi
authors.forename: K
authors.initials: K
authors.lastname: Taguchi
authors.forename: S
authors.initials: S
authors.lastname: Aishima
authors.forename: S
authors.initials: S
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Shimada
authors.forename: K
authors.initials: K
authors.lastname: Kajiyama
authors.forename: K
authors.initials: K
authors.lastname: Sugimachi
authors.forename: M
authors.initials: M
authors.lastname: Tsuneyoshi
mesh_terms: D000368:Aged; D001483:Base Sequence; D001650:Bile Duct Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001653:Bile Ducts, Intrahepatic / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D018281:Cholangiocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000235:genetics; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D018807:Polymorphism, Single-Stranded Conformational; D015534:Trans-Activators; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D004273:DNA, Neoplasm; D015534:Trans-Activators; D051176:beta Catenin