Immunohistochemical detection of BH3-only proteins in ameloblastic tumors

Objective: To evaluate expression of BH3-only proteins in odontogenic tumors, expression of Bid, Bim, Bad, Noxa, and Puma was analyzed in ameloblastic tumors as well as in tooth germs. Methods: Nine tooth germs, 37 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with antibodies against Bid, Bim, Bad, Noxa, and Puma. Results: Immunohistochemical reactivity for Bid, Bim, Bad, Noxa, and Puma was detected in the cytoplasm of cellular components in normal and neoplastic odontogenic tissues. Expression of these BH3-only proteins was evident in odontogenic epithelial cells near the basement membrane in tooth germs and ameloblastic tumors. Acanthomatous ameloblastomas showed no reactivity for Bid, Bim, Bad, Noxa, or Puma in keratinizing cells, whereas granular cells in granular cell ameloblastomas reacted with these BH3-only proteins. Basal and desmoplastic ameloblastomas and ameloblastic carcinomas showed immunoreactivity for the BH3-only proteins in most neoplastic cells. Conclusion: Expression of Bid, Bim, Bad, Noxa, and Puma in tooth germs and ameloblastic tumors suggests that the BH3-only proteins have a role in apoptotic cell death of normal and neoplastic odontogenic epithelium. Distinctive expression patterns of these BH3-only proteins in ameloblastoma variants suggest that the BH3-only proteins might be involved in tumor cell differentiation of ameloblastomas.