Expression of cyclo-oxygenase-2 enzyme in the tissue samples of patients with various clinicopathological stages of oral leukoplakia and oral squamous cell carcinoma

Abstract

Aim: The purpose of this study was to evaluate the expression of cyclo-oxygenase-2 (COX-2) enzyme in the tissue samples of patients with various clinicopathological stages of oral leukoplakia and oral squamous cell carcinoma (OSCC). Materials and Methods: The samples for the study were divided into 4 groups. Group A comprised 20 healthy individuals with no habits. Twenty healthy individuals with habitual tobacco usage and no oral lesions were included in Group B. Twenty cases of leukoplakia diagnosed clinically and histopathologically were included in Group C. Staging was done using the modified classification and staging system of oral leukoplakia. Twenty cases of OSCC diagnosed clinically and histopathologically were included in Group D. Immunohistochemical staining was done on these 80 samples (paraffin blocks) for COX-2 expression by indirect method using polymer based Horseradish peroxidase system. Statistical analysis was performed using Kruskal-Wallis test and Spearman's rank correlation test. Results: Significant and proportional increase of COX-2 staining was noted with the increase in the severity of dysplasia. Eighty percent of OSCC expressed COX-2, increasing in its intensity of staining with the decrease in differentiation. Seventy five percent of leukoplakia showed positive COX-2 expression. Only 15% of positive controls were COX-2 positive. No normal mucosa showed positive expression of COX-2. Conclusion: High expression of COX-2 is seen in advanced stages of leukoplakia and OSCC. Hence, COX-2 enzyme increases cell proliferation, promotes angiogenesis and inhibits immune surveillance in carcinogenesis; it can be an early detection marker in oral leukoplakia and a prognostic marker of OSCC.