The expression and mutation of β-catenin in colorectal traditional serrated adenomas.

ABSTRACT

Context Exon 3 mutation of β-catenin is associated with the carcinogenesis. Aims: In this study we aimed to detect the expression of exon 3 mutations of β-catenin in colorectal TSA, TA/VTA, and CRC. Materials and Methods: Immunohistochemistry staining for β-catenin was performed for 30 TSA, 20 tubular adenomas (TA)/villous tubular adenomas (VTA), and 21 colorectal carcinoma (CRC) cases. DNA sequencing of the exon 3 of β-catenin gene was performed for 8 TSA cases, 6 TA cases, 5 VTA cases, and 10 CRC cases with positive staining in the nuclei and cytoplasm. Statistical Analysis: A Fisher exact test and chi-square test were used to analyze the differentiations of the expression of β-catenin in TSA, TA/VTA, and CRC. Results: The percentages of β-catenin expression in TSA, TA/VTA, and CRC were 76.6% (23/30), 70.0% (14/20), and 95.2% (20/21), respectively, and were significantly different among these three types of tissue specimens (χ2 = 22.805, P < 0.001). Although β-catenin expression levels in TSA were not related to it in TA/VTA, they were significantly different between TSA/TA/VTA and CRC. The degree of dysplasia was well correlated with β-catenin expression (TSA P < 0.01; TA/VTA P < 0.05). But β-catenin exon 3 mutations were not detected in any of these tissue specimens. Conclusions: Aberrant β-catenin expression is associated with the degree of dysplasia in TSA. β-catenin likely plays an important role in the pathogenesis of colorectal TSA and conventional adenomas.