Immunocytochemical localization of bone morphogenetic proteins (BMPs) in salivary gland pleomorphic adenoma

The localization of bone morphogenetic protein (BMP)-1, -2, -3 and transforming growth factor (TGF)-beta in normal salivary gland and pleomorphic adenoma of the salivary gland has been examined immunocytochemically. Tumor cells with BMP immunostaining in pleomorphic adenoma were associated with some solid cellular and tubuloglandular patterns, and with stellate cells in the myxoid area. In addition, in the chondroid area of three pleomorphic adenomas, chondrocyte-like cells were positive for BMPs. It is speculated that BMPs secreted by the tumor cells play a role in the formation of the chondroid component in pleomorphic adenoma by inducing some tumor cells, probably neoplastic myoepithelial cells, to differentiate to chondrocytes by metaplastic change. No tumor cells specifically immunostained with TGF-beta were found. TGF-beta was positive in fibrous and hyalinized stroma. In the submandibular gland, only anti-BMP-1 antibody specifically reacted to apical portions of degenerated serous acinar cells.