Activation of the Wnt/β-catenin signaling pathway and CTNNB1 mutations in canine intestinal epithelial proliferative lesions

J Vet Med Sci. 2024 Jul 2;86(7):748-755. doi: 10.1292/jvms.24-0125. Epub 2024 May 29.

Abstract

Nuclear expression of β-catenin has been reported in canine intestinal epithelial tumors (IETs) and colorectal inflammatory polyps (CIPs) with dysplastic epithelia. However, the role of the Wnt/β-catenin signaling pathway in these lesions remains unclear. To investigate the association between the nuclear β-catenin expression and the activation of the Wnt/β-catenin signaling pathway, immunohistochemistry and mutation analyses were conducted on 64 IETs and 20 CIPs. IETs and CIPs with β-catenin nuclear and/or cytoplasm immunolabeling were classified as β-catenin (+). The immunostaining scores of c-Myc and Cyclin D1 and Ki-67 index were significantly higher in β-catenin (+) cases than in β-catenin (-) cases. Identical APC mutations (p.E154D and p.K155X) were detected in 6/41 β-catenin (+) IETs; all 6 of IETs with APC mutations were Jack Russell Terriers. CTNNB1 mutations were detected in 29/42 β-catenin (+) IETs, 3/11 β-catenin (+) CIPs, and 2/22 β-catenin (-) IETs, most of which were hotspots associated with human colorectal carcinoma. In one Miniature Dachshund diagnosed with a CIP that subsequently developed into an IET, the same CTNNB1 mutation was detected in both lesions. The immunohistochemical results suggest that cell proliferative activity in β-catenin (+) cases may be associated with activation of the Wnt/β-catenin signaling pathway. The mutation analysis results suggest that CTNNB1 mutations may be associated with cytoplasmic β-catenin accumulation in IET and CIP. Furthermore, the dysplastic epithelium in CIP may progress to IET through the activation of the Wnt/β-catenin signaling pathway by the CTNNB1 mutation.

Keywords: colorectum inflammatory polyp; dog; immunohistochemistry; intestinal epithelial tumor; β-catenin.

MeSH terms

  • Animals
  • Dog Diseases* / genetics
  • Dog Diseases* / metabolism
  • Dog Diseases* / pathology
  • Dogs
  • Female
  • Immunohistochemistry / veterinary
  • Intestinal Mucosa / metabolism
  • Intestinal Mucosa / pathology
  • Intestinal Neoplasms / genetics
  • Intestinal Neoplasms / metabolism
  • Intestinal Neoplasms / pathology
  • Intestinal Neoplasms / veterinary
  • Male
  • Mutation*
  • Wnt Signaling Pathway* / genetics
  • beta Catenin* / genetics
  • beta Catenin* / metabolism

Substances

  • beta Catenin