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 cytodifferentiation of odontogenic epithelium, the expression of bcl-2, bcl-x and bax proteins was examined immunohistochemically in tooth germs and various types of ameloblastoma. In ameloblastomas, bcl-2 and bcl-x proteins were expressed intensely in peripheral columnar cells and weakly in central polyhedral cells, while bax protein reactivity was low. In variants of ameloblastoma, no expression of these proteins was found in the keratinizing areas or granular cell clusters. Basal cell ameloblastomas showed intense reactivity for bcl-2 and bcl-x proteins, but slight or no reactivity for bax protein. These results indicate that in ameloblastomas the bcl-2 family proteins might function primarily as anti-apoptotic factors, reflecting proliferative activity. Malignant ameloblastomas showed decreased reactivity for bcl-2 protein and increased levels of bax protein as compared with benign ones.