title: The Wnt-signaling pathway is not implicated in tumorigenesis of Merkel cell carcinoma.
abstract: BACKGROUND
  The Wnt-signaling pathway, involving beta-catenin, apc, and axin, plays a critical role in numerous developmental events. Alterations in the Wnt-signaling pathway have been detected in a wide variety of neoplasms. However, similar aberrations have not been described in Merkel cell carcinoma (MCC). The aim of this study was to determine the status of the Wnt-signaling pathway in MCC.
  
  
  METHODS
  Twelve cases of MCC were tested for the expression of beta-catenin and mutational status of CTNNB1 (gene for beta-catenin), APC, AXIN1, and AXIN2. Genomic DNA extracted from paraffin blocks was subjected to a polymerase chain reaction/single-strand conformation polymorphism analysis and sequencing.
  
  
  RESULTS
  Nuclear accumulation of beta-catenin was observed in only one case (8.3%), as determined by immunochemistry. No mutations were found in CTNNB1, APC, and AXIN2 in all cases, although silent mutations in AXIN1 were detected in three cases.
  
  
  CONCLUSIONS
  We conclude that the Wnt-signaling pathway does not play an important role in tumorigenesis in MCC.
authors.affiliation: First Department of Pathology, Faculty of Medicine, Oita University, Oita, Japan.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Daa
authors.forename: Kenji
authors.initials: K
authors.lastname: Kashima
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kondoh
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060466:Axin Protein; D015266:Carcinoma, Merkel Cell / Q000209:etiology*; D002467:Cell Nucleus / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics; D005260:Female; D017491:Genes, APC; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D015398:Signal Transduction; D012878:Skin Neoplasms / Q000209:etiology*; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: C491761:AXIN2 protein, human; D060466:Axin Protein; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D051153:Wnt Proteins; D051176:beta Catenin