ABSTRACT
BACKGROUND: The B cell lymphoma‑2 gene is a proto‑oncogene whose protein product inhibits apoptosis. Its role is associated with keeping cells alive, but not by stimulating them to proliferation, as other proto‑oncogenes do. Increased expression of protein product of Bcl‑2 gene appears in the early phase of carcinogenesis leading to apoptosis impairment and in consequence to the progression of neoplastic changes. OBJECTIVE: To evaluate and compare the expression of Bcl‑2 protein in oral epithelial dysplasia and oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Sixty cases of formalin‑fixed paraffin‑embedded archival specimens comprising of 30 cases of leukoplakia with oral epithelial dysplasia and 30 cases of OSCC were taken for immunohistochemical analysis using monoclonal antibody against anti‑human Bcl‑2 oncoprotein. RESULTS: Immunostaining for Bcl‑2 protein was identified in basal and parabasal layers as granular cytoplasmic staining in oral epithelial dysplasia. In OSCC, Bcl‑2 immunoreactivity was most prominent in the peripheral cells of the infiltrating tumor islands which diminished toward the center in well‑differentiated and moderately differentiated OSCC, whereas stronger and more diffuse expression of Bcl‑2 oncoprotein was seen in poorly differentiated OSCC. Overall positivity of 26.7% (8/30) was observed in oral epithelial dysplasia and 30% (9/30) in OSCC in this study. INTERPRETATION AND CONCLUSION: Altered expression of Bcl‑2 oncoprotein may be an early molecular event which leads to prolonged cell survival, increased chances of accumulation of genetic alterations, and subsequent increase in malignant transformation potential.