Immunohistochemical analysis of bcl-2 family proteins in benign and malignant ameloblastomas

To study the possible roles of bcl-2 family proteins in oncogenesis and cyt odifferentiation of odontogenic epithelium, the expression of bcl-2, bcl-x and bar proteins was examined immunohistochemically in tooth germs and vari ous types of ameloblastoma. In ameloblastomas, bcl-2 and bcl-x proteins wer e expressed intensely in peripheral columnar cells and weakly in central po lyhedral cells, while bar protein reactivity was low. In variants of amelob lastoma, no expression of these proteins was found in the keratinizing area s or granular cell clusters. Basal cell ameloblastomas showed intense react ivity for bcl-2 and bcl-x proteins, but slight or no reactivity for bar pro tein. These results indicate that in ameloblastomas the bcl-2 family protei ns might function primarily as anti-apoptotic factors, reflecting prolifera tive activity. Malignant ameloblastomas showed decreased reactivity for bcl -2 protein and increased levels of bar protein as compared with benign ones .