Expression of gastric mucin MUC5AC and gastric transcription factor SOX2 in ampulla of vater adenocarcinoma: comparison between expression patterns and histologic subtypes.

The purpose of this study was to examine the expression pattern of MUC5AC and SOX2 in ampulla of vater adenocarcinoma and evaluate the association between expression of these gastric epithelial markers and the histologic phenotype of ampulla of vater carcinoma. Six surgically resected samples of ampulla of vater adenocarcinoma, including four intestinal type carcinomas and two pancreatobiliary type carcinomas, were studied. We performed immunohistochemistry with a monoclonal antibody against MUC5AC and a polyclonal anti-SOX2 antibody. In two of the four intestinal type carcinomas, MUC5AC and SOX2 were focally expressed in the superficial neoplastic mucosa. However, in the centre of the tumour and in other invasive lesions, including vascular invasive lesions and metastatic lymph nodes, neither MUC5AC nor SOX2 was expressed. In contrast, in both pancreatobiliary type carcinomas, expression of MUC5AC and SOX2 was maintained or increased in invasive lesions. Our immunohistochemistry data suggest that MUC5AC and SOX2 are associated with the pancreatobiliary phenotype of ampulla of vater carcinoma and involved in later events in carcinogenesis, such as invasion and metastasis.