Beta-Catenin Expression in Intramucosal Neoplastic Lesions of the Stomach

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Abstract
Objective: To clarify roles of beta-catenin in the early stage of gastric tumorigenesis, we investigate beta-catenin expression in stomach intramucosal neoplasms. Methods: For immunohistochemistry, 84 gland-forming neoplasms and 17 signet-ring cell carcinomas were examined. The gland-forming neoplasms were grouped according to the Vienna classification: group A (low-grade adenoma/dysplasia), group B (high-grade adenoma/dysplasia) and group C (intramucosal carcinoma). Results: Strong nuclear expression was detected not only in group C (21.4%) but in groups A (20.8%) and B (11.2%). Strong cytoplasmic expression was detected in groups A, B and C: 16.7, 11.2 and 16.7%, respectively. Loss of membranous stainings (LOM) were also detected in groups A, B and C: 20.8, 22.2 and 31.0%, respectively. No significant difference was found among groups A, B and C with respect to nuclear, cytoplasmic, and membranous expression. Regarding signet-ring cell carcinomas, all cases were essentially negative for nuclear expression and 11.8% of the cases showed weak cytoplasmic expression as well as LOM. There were obvious differences between gland-forming adenocarcinoma and signet-ring cell carcinoma with respect to nuclear and cytoplasmic expression but not in terms of membranous expression. Conclusion: These findings suggest that beta-catenin expression does not always reflect the malignant transformations in the early stage of gastric tumorigenesis.