NEOPLASTIC ODONTOGENIC EPITHELIAL-CELLS EXPRESS BONE SIALOPROTEIN

Bone sialoprotein (BSP) is synthesized and secreted by bone-, dentine- and cementum-forming cells and has been implicated in de novo bone for mation and mineralization. In this study, we used histological section s of odontogenic neoplasms and performed immunohistochemical and in si tu hybridization analyses. In ameloblastoma, BSP mRNA signals were see n in the neoplastic epithelial cells forming nests, strips and islands . BSP deposition was also seen in the stellate reticulum of the tumour masses revealed by immunohistochemistry using human BSP antibodies. I n calcifying epithelial odontogenic tumour, the calcified masses demon strated positive immunoreactivity to the human BSP antibodies, and the hybridization signals for BSP were located in the cells near the calc ified particles. In the calcifying odontogenic cyst, strong BSP signal s were seen in cells surrounding the characteristic nests of ghost cel ls, which often calcify subsequently. BSP protein was also found in th ese cells by immunohistochemistry. The active expression of BSP in the epithelial elements of the odontogenic tumours of adult patients sugg ests the activation of this matrix protein gene in the neoplastic proc ess, and that BSP may play an important role in tumour formation and d ifferentiation with respect to pathological calcification. (C) 1998 Ch apman & Hall.