EXPRESSION OF BCL-2 IN SALIVARY-GLANDS AND SALIVARY-GLAND ADENOMAS - A CONTRIBUTION TO THE RESERVE CELL THEORY

The bcl-2 proto-oncogene product inhibits apoptosis. It has been sugge sted that bcl-2 assists the survival of stem cells. Bcl-2 also plays a role in the development of adenomas. In salivary glands it is express ed in basal cells of striated and excretory ducts which may indicate t hat these cells are reserve cells. Acinar cells, myoepithelial cells a nd most luminal cells are negative for bcl-2. In basal cell adenomas a nd Warthin's tumors it is found predominantly in cells with basal cell differentiation. In pleomorphic adenomas bcl-2 is expressed mainly in basal cells of tubulo-ductal structures, at various degrees and patte rns in solid and trabecular areas and at low degree in myxoid areas. I n chondroid areas of pleomorphic adenomas, in myoepitheliomas and onco cytomas it is only focally expressed or missing. If the inhibition of apoptosis plays a significant role in the genesis of these neoplasms, then factors other than bcl-2 must be effective.