Expression of odontogenic ameloblast‐associated protein, amelotin, ameloblastin, and amelogenin in odontogenic tumors: immunohistochemical analysis and pathogenetic considerations

Abstract

Screening for expression of amelogenesis-related proteins represents a powerful molecular approach to characterize odontogenic tumors and investigate their pathogenesis. In this study, we have examined the presence and distribution of odontogenic ameloblast-associated protein (ODAM), amelotin (AMTN), ameloblastin (AMBN), and amelogenin (AMEL) by immunohistochemistry in samples of adenomatoid odontogenic tumor (AOT), calcifying epithelial odontogenic tumor (CEOT), developing odontoma, ameloblastoma, calcifying cystic odontogenic tumor (CCOT), ameloblastic fibroma (AF), myxoma, odontogenic fibroma (OF), and reduced enamel epithelia (REE). Positive results were obtained in those tumors with epithelial component, except for AF, OF, and ameloblastoma. ODAM was found around mineralized structures (dystrophic calcifications) and CEOT's amyloid, whereas AMTN stained the eosinophilic material of AOTs. The CCOT transitory cells to ghost cells were strongly positive with all proteins except AMEL, and the REE as well as odontomas showed immunoexpression for ODAM, AMTN, AMBN, and AMEL similar to those found in normal rat tooth germs. Based on these results, some histopathogenetic theories were formulated.

Current Concepts and Occurrence of Epithelial Odontogenic Tumors: I. Ameloblastoma and Adenomatoid Odontogenic Tumor

“…The overexpression or underexpression of important signaling molecules may play an important role in the tumorigenesis of ameloblastomas. First of all, several proteins expressed in the enamel epithelium during the early stage of tooth formation, including amelogenin,11 tuftelin,12 and ameloblastin,13,14 are specifically expressed in tumor cells of ameloblastomas, but enamelin and amelotin expressed in the mineralizing stage of tooth formation are rarely positive in tumor cells of ameloblastomas 15,16…”

“…Enamel proteins including amelogenin, ameloblastin, and amelotin, as well as TGF-β/SMADs, are more intensely expressed in AOTs than in ameloblastomas. Therefore, AOTs exhibit less aggressive biological behavior and increased cytodifferentiation and apoptosis than ameloblastomas 16,30…”

The Diagnostic Usefulness of Immunohistochemistry for Odontogenic Lesions

“…Morphology and histochemical stains (Congo red or Thioflavin-T) are currently more likely to be of help than IHC in its assessment. However, recent investigation of a number of odontogenic epithelia associated proteins, such as odontogenic ameloblast-associated protein (ODAM), may yet yield useful biomarkers [31].…”

Maturation and beyond: proteins in the developmental continuum from enamel epithelium to junctional epithelium

“…ODAM has further been found in other types of lung and breast tumors of epithelial origin and has been suggested as a prognostic marker for such neoplasms (Kestler et al, 2008), particularly human breast cancer (Siddiqui et al, 2009). Other descriptive work focusing on the expression of enamel proteins has confirmed the expression of ODAM and AMTN in certain types of odontogenic tumors (Ren et al, 2011; Crivelini et al, 2012), often associated with sites of mineral deposition (Stolf et al, 2013). ODAM expression has further been described in odontoblasts, osteoblasts and various cancer cells (Lee et al, 2012b).…”