Study of immunohistochemical demonstration of Bcl-2 protein in ameloblastoma and keratocystic odontogenic tumor

BACKGROUND: The Bcl-2 (B-cell lymphoma) gene product also known as apoptotic inhibitor is expressed in many normal and tumor tissues. This Bcl-2 gene protects the cell by blocking postmitotic differentiation from apoptosis, thus maintaining the stem cell pool. OBJECTIVE: To study the expression of Bcl-2 protein in ameloblastoma and keratocystic odontogenic tumor (KCOT) to determine their apoptotic behaviors and to analyze biological nature of KCOT, which has higher proliferative potential and aggressive clinical behavior like odontogenic tumors. MATERIALS AND METHODS: Formalin-fixed paraffin sections of ameloblastoma (n = 20) and KCOT (n = 20) are considered for immunohistochemical analysis using monoclonal antibody against antihuman Bcl-2 oncoprotein. Lymphomas (n = 3) were used as controls. STATISTICAL ANALYSIS: The statistical analysis was performed using software package of social science version 16. The data were analyzed using Chi-square test and Student's t test. In all the above tests, P < 0.05 was accepted as statistically significant. RESULTS: The positive ratio of Bcl-2 was 85% (17/20) in ameloblastoma, 85% (17/20) in KCOT and 100% (3/3) in lymphomas. Bcl-2 was expressed in peripheral cells and few scattered cells of stellate reticulum in ameloblastoma. KCOT showed strong positivity for Bcl-2 mainly in the basal layer. INTERPRETATION AND CONCLUSION: The present study demonstrates the aggressive nature of KCOT and intrinsic growth potential of its lining epithelium. This study clearly demonstrates that KCOT like ameloblastoma demonstrates aggressive clinical and noticeable invasive behavior. Therefore, it is now considered as no longer a developmental cyst but as odontogenic tumor.