Immunohistochemical detection of β-catenin and adenomatous polyposis coli in ameloblastomas

BACKGROUND: To clarify the roles of the Wnt signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, expression of beta-catenin and adenomatous polyposis coli (APC) was analyzed in ameloblastomas as well as in tooth germs. METHODS: Tissue specimens of 10 tooth germs, 40 benign ameloblastomas, and five malignant ameloblastomas were examined immunohistochemically with the use of antibodies against beta-catenin and APC. RESULTS: Immunohistochemical reactivity for beta-catenin was detected in the cell membrane and cytoplasm of most odontogenic epithelial cells in tooth germs and ameloblastomas. Nuclear beta-catenin expression was recognized in nine of 40 ameloblastomas and two of five malignant ameloblastomas, but not in tooth germs. APC was evidently expressed in odontogenic epithelial cells neighboring the basement membrane in tooth germs and ameloblastomas, and the reactivity was significantly lower in benign and malignant ameloblastomas than in tooth germs. Follicular ameloblastomas and acanthomatous ameloblastomas tended to show high nuclear beta-catenin expression and low APC reactivity, as compared with other ameloblastoma variants. CONCLUSION: Expression of beta-catenin and APC in tooth germs and ameloblastomas suggests that aberration of the Wnt signaling pathway might play a role in oncogenesis and cytodifferentiation of odontogenic epithelium via deregulation of cell proliferation.