Enamelysin is a tooth-specific
protease that was initially isolated from porcine enamel organ and subsequently from human odontoblasts. Since this
protease is thought to play important roles in tooth development, the evaluation of
enamelysin in
odontogenic tumors may aid our understanding of the histogenesis and cell differentiation of such lesions. A
monoclonal antibody (203-1C7) was generated against synthesized human
enamelysin oligopeptide and was used to assess the immunolocalization of
enamelysin in healthy developing tooth germs and various types of odontogenic lesions. In tooth germs,
enamelysin expression was detected only in the secretory enamel. Thus, 203-1C7 may serve as an enamel-specific marker in the late stage of enamel matrix development and calcification. In odontogenic lesions, strong
enamelysin staining was demonstrated in the immature enamel matrix of
ameloblastic fibro-odontomas and
odontomas. Furthermore,
enamelysin was also detected in globular
amyloid masses and calcified foci in calcifying epithelial
odontogenic tumors, hyaline droplets, small and large mineralized areas in adenomatoid
odontogenic tumors, and a portion of ghost cells in
calcifying odontogenic cysts. Positive reactivity was also observed in selected
tumor cells in some of these
tumors. No intracellular staining for
enamelysin was detected in
ameloblastomas or the ameloblastic portion of
ameloblastic fibro-odontomas. Also,
enamelysin was not detected in dentin, dysplastic dentinoid hyaline matrices, and cementum that were present within the
tumors examined. Thus, taken together, our results suggest that the
enamelysin-specific
monoclonal antibody (203-1C7) may be utilized as a marker of early enamel development and that
enamelysin may be involved in the pathogenesis of specific
odontogenic tumors.