Clinicopathological Analysis of β-catenin and Axin-1 in Solid Pseudopapillary Neoplasms of the Pancreas
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Solid pseudopapillary neoplasm (SPN) is a distinct pancreatic neoplasm and has characteristic, aberrant nuclear expression of β-catenin in most cases. However, alterations in components of the Wnt pathway, other than the β-catenin (CTNNB1) gene mutation, have not been identified. In this study, we investigated the status of Axin-1, the spectrum of mutations in the CTNNB1 gene, and the clinicopathological features of SPNs.
Materials and Methods
We collected 27 SPNs from 25 patients. A tissue microarray was constructed to perform immunohistochemistry for β-catenin, E-cadherin, and Axin-1. The CTNNB1 and AXIN1 gene mutations were analyzed by DNA sequencing. Finally, the clinicopathological features of SPNs were analyzed for association with the CTNNB1 mutations and the Axin-1 alterations.
All 27 SPNs expressed nuclear immunoreactivity of β-catenin and exhibited a lack of membranous decoration of E-cadherin. All SPNs harbored CTNNB1 gene mutations. No alterations were present in the AXIN1 gene, and the immunohistochemical analysis revealed weak or absent reactivity of Axin-1 in the cytosol. All cases with a codon-37 CTNNB1 mutation had weak Axin-1 immunoreactivity in the cytoplasm (P = 0.018). No other significant correlation was found between clinicopathological parameters, CTNNB1 mutations, and Axin-1 alterations.
Nuclear β-catenin immunoexpression is characteristic for SPNs and corresponds to the CTNNB1 mutation. The Wnt pathway is involved in the tumorigenesis of SPNs, primarily through the alteration of β-catenin. Despite the absence of any identifiable genetic mutation, a low level of Axin-1 in the cytoplasm might contribute to the aberrant distribution of β-catenin in SPNs.
KeywordsEsophageal Squamous Cell Carcinoma Adenomatous Polyposis Coli Laser Capture Microdissection Solid Pseudopapillary Neoplasm Purify Polymerase Chain Reaction Product
The work was supported by the grant DOH99-TD-C-111-006 from the Department of Health, Republic of China, and the grant CMRPG360923 and CMRPG340313 from the Chang Gung Memorial Hospital.
There is no disclosure of any commercial interest and the source of any financial or material support.
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