Immunoexpression of cyclooxygenase-2 and p53 in oral squamous cell carcinoma

Cyclooxygenase-2 (COX-2) is an induced proinflammatory enzyme involved in various steps of carcinogenesis such as cell proliferation, reduction in apoptosis rates, and promotion of tumor angiogenesis. Mutation or inactivation of the tumor suppressor gene p53 is frequently observed in malignant neoplasms and is known to be involved in the early stages of carcinogenesis. Recent studies reveal a possible correlation between COX-2 and p53 expression in several malignant neoplasms. The present study analyzed the correlation between the expression of COX-2 and p53 in oral squamous cell carcinoma (OSCC) and evaluated the differences in the expression of these 2 proteins according to the histologic grade of malignancy of the tumor.

Thirty-four cases of OSCC were graded according to the histologic grading system proposed by Bryne [Oral Dis 4(2) (1998) 70-77]. Immunoexpression of COX-2 and p53 was analyzed by counting 1000 neoplastic cells in 5 different fields at the deep invasive front of the tumor under a light microscope. On the basis of the number of immunopositive cells, the labeling index expressed as the percentage of positively stained cells was established for each marker.

Increased COX-2 expression in most specimens was observed, although no significant correlation was observed between COX-2 and p53 labeling indices (P > .05). Moreover, there were no significant differences in the expression of these proteins between high- and low-grade tumors (P > .05).

The increased expression of COX-2 in OSCC suggests a role for this protein in the pathogenesis and progression of oral cancer.