Evaluation of Transforming Growth Factor Beta 1 Expression in Ameloblastoma, Calcifying Odontogenic Cyst and Odontogenic Keratocyst

Introduction: Ameloblastoma is the most common neoplasm of odontogenic epithelium with locally aggressive behavior resulting in recurrence and malignant transformation. Odontogenic cysts are common lesions of the jaws with different biological behavior. Odontogenic keratocyst (OKC) and calcifying odontogenic cyst (COC) with ameloblastoma-like epithelium (ameloblastic type) are more aggressive than other odontogenic cysts. Therefore, these lesions were classified as odontogenic tumors by WHO. Transforming growth factor beta 1 (TGF-β1) is a secretory protein with diverse cellular functions including epithelial differentiation during tooth development and pathological processes such as tumorigenesis. It can function as a strong tumor suppressor gene during initial stages of tumor development. The aim of this study was to evaluate the TGF-β1 expression in ameloblastoma, OKC and COC with varying biological behavior. Materials and Methods: We examined TGF-β1 expression in epithelial and stromal cells of 15OKCs, 15COCs (ameloblastic type) and 15 ameloblastomas by immunohistochemistry. Results: Immunoreactivity was observed in epithelial and stromal cells of all lesions with different degrees. There was statistically significant reduced immunoexpression in epithelial cells of ameloblastomas and COCs compared to OKCs, whereas significant reduced immunoreactivity was reported in stromal cells of OKCs. There was no statistically significant difference between COCs and ameloblastomas in both stromal and epithelial cells immunoreactivity which shows their similar bilological behavior. Conclusion: Reduced TGF-β1 immunoexpression in epithelial cells of ameloblastomas and COCs compared to OKCs could be associated with the primitive phenotype and more invasive biological behavior of these lesions. Reduced stromal expression of TGF-β1 in OK1Cs could be explained by its looser stroma than other studied lesions.