Immunohistochemical Expression of Integrins and CD44 in Ameloblastomas

To clarify the role of cell adhesion molecules in epithelial odontogenic tumors, expression of integrin α2, α3 and β4 subunits and the standard form of CD44 was immunohistochemically examined in 22 ameloblastomas as well as in 1 clear cell odontogenic tumor (CCOT). Integrin α2 and α3 subunits were expressed on the cell membrane of peripheral columnar or cuboidal cells in ameloblastomas. Most tumor cells in basal cell ameloblastomas and the CCOT were positive for these subunits. These features suggest that CCOT possesses characteristics similar to those of peripheral cells in main type ameloblastoma or neoplastic cells in basal cell ameloblastoma. Integrin β4 subunit was found along the basement membrane in ameloblastomas and the CCOT. The expression of these representative epithelial integrins at the epithelialmesenchymal interfaces suggests that they might mediate parenchymal-stromal cell interactions in epithelial odontogenic tumors. CD44 was detected in most tumor cells of ameloblastomas and the CCOT, but keratinizing areas in acanthomatous ameloblastomas showed decreased CD44 expression. These features suggest that CD44 is involved not only in cell adhesion but also in cellular differentiation in epithelial odontogenic tumors.