Expression of Bcl-2 and MIB-1 Markers in Oral Squamous Cell Carcinoma (OSCC)- A Comparative Study.

BACKGROUND Neoplasia results from various genetic and epigenetic factors. Our study focused on the pathogenesis which involved an imbalance in various molecular mechanisms which regulated cell proliferation and apoptosis. The anti-apoptotic mechanism is regulated by Bcl-2 gene, while Ki-67 is expressed exclusively in nuclei of proliferating cells. This study was done to evaluate the basic pathologic process which underlay well and poorly differentiated oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS Thirty cases of oscc were selected, out of which 11 were well differentiated, 9 were moderately differentiated and 10 were poorly differentiated. Three slides of 4μm thickness were prepared out of each sample, which were then subjected to Hematoxylin and eosin stain (H&E) staining and two types of immunohistochemical (IHC) staining. Immunohistochmical markers used were Ki-67 (proliferative marker using MIB-1 (Molecular Immunology Borstel 1) antibody) and Bcl-2 (anti-apoptotic marker). The number of MIB-1 and Bcl-2 positive cells was calculated from ten different high power fields, by counting the number of positive cells per 50 cells in each field, by making a grid pattern. The overall percentage value for each case was evaluated for MIB-1 and Bcl-2 positive cells. Karl-Pearson's co-relation coefficient was calculated between MIB-1 and Bcl-2 in each group. The aim of this study was to co-relate the expression of Ki-67, a proliferative marker, by using MIB-1 antibody and Bcl-2, an anti-apoptotic marker in various grades of oscc and also to determine whether there was any co-relation between these two markers in the 30 cases of oscc . RESULTS A statistically significant increase for MIB-1 and a statistically significant decrease for Bcl-2 was found in well to moderately to poorly differentiated Squamous cell carcinoma (SCC). A statistically significant co-relation was also found between MIB-1 and Bcl-2 in poorly differentiated oscc . CONCLUSION MIB-1 expression is predominant in well, moderate and poorly differentiated SCCs. Bcl-2 expression is predominant in well differentiated than in moderately and poorly differentiated oscc , which suggested that apoptosis probably played a major role in the early stages of carcinogenesis.