Differential expression of cyclooxygenase-2 and cyclin D1 in salivary gland tumors

Salivary gland tumors are complex and have a great histomorphological diversity; more than 30 histological subtypes are currently described and the study of proteins that help understand and differentiate these tumors is essential. We aimed to analyze the immunoexpression of cyclooxygenase-2 (COX-2) and cyclin D1 proteins in pleomorphic adenomas (PA), mucoepidermoid carcinomas (MEC) and adenoid cystic carcinomas (AdCC) of salivary glands.

A total of 38 PA, 12 AdCC and 12 MEC underwent immunohistochemical study by the polymeric biotin-free technique. Immunopositive cells were analyzed semi-quantitatively. For statistical analysis, a significance level was set at p ≤ 0.05.

Overall, these tumors were more prevalent in women (n = 37). The mean age of these patients was 58-year-old and the parotid gland was the most affected anatomic site (n = 33). All cases of AdCC and MEC showed immunopositivity to cyclin D1; however, 39.5% of the PAs were negative (p < 0.001). Regarding COX-2 immunoexpression, we observed that all cases of CME were positive, whereas 60.5% of the PA and 75% of the CAC analyzed were completely negative (p = 0.042).

The overexpression of COX-2, observed only in MEC, emphasizes that salivary gland tumors have different profiles. Cyclin D1 is more immunoexpressed in malignant tumors. Together, these immunohistochemical findings may be useful in differentiating the studied tumors.