Expression of astrocyte elevated gene-1 protein in ameloblastomas, keratocystic odontogenic tumors, and dentigerous cysts.

BACKGROUND: Benign epithelial odontogenic tumors such as ameloblastoma and keratocystic odontogenic tumor (KCOT) may exhibit an aggressive clinical course reminiscent of malignancies. Recent studies have indicated that astrocyte elevated gene-1 (AEG-1) is highly expressed in a variety of malignant neoplasms and its overexpression is associated with tumor invasion, metastasis, and poor survival. However, the role of AEG-1 in odontogenic tumors and cysts is still undiscovered. METHODS: Immunohistochemical staining of AEG-1 was performed in 42 cases of ameloblastoma, 29 cases of KCOT, and 19 cases of dentigerous cyst. Correlations between AEG-1 expression and clinical parameters of ameloblastomas or KCOTs were statistically analyzed. RESULTS: AEG-1-positive staining was found in 37 (88%) of 42 ameloblastomas and in 24 (83%) of 29 KCOTs. None of 19 dentigerous cysts were positive for AEG-1 protein. For ameloblastomas, AEG-1 protein expression was significantly higher in ameloblast-like cells than in stellate reticulum-like cells (P = 0.003). For KCOTs, AEG-1 protein was diffusely expressed in all lining epithelial cells except the superficial parakeratinized cells. Moreover, the frequency of cortical plate perforation was significantly higher in ameloblastomas with high AEG-1 expression than in ameloblastomas with low or negative AEG-1 expression (P = 0.043). CONCLUSION: Significantly higher expression of AEG-1 protein in ameloblastomas and KCOTs than in dentigerous cysts and significantly greater frequency of cortical plate perforation in high AEG-1-expressed ameloblastomas than in low or negative AEG-1-expressed ameloblastomas may imply the high potential of AEG-1 to serve as a locally invasive biomarker and a target for novel therapy.