Title: Overexpression of cyclooxygenase‐2 correlates with cytoplasmic HuR expression in salivary mucoepidermoid carcinoma but not in pleomorphic adenoma
Abstract: Background: The overexpression of cyclooxygenase (COX)‐2 in several human carcinomas suggests that COX‐2 is related to carcinogenesis. Although COX‐2 expression has been shown to be up‐regulated in carcinomas of the salivary gland, its mechanisms are not completely understood. HuR is an mRNA‐binding protein that controls the stability of certain transcripts including COX‐2. Methods: The expression of COX‐2 and HuR was determined by immunohistochemistry in 28 cases of salivary pleomorphic adenoma and 18 cases of salivary mucoepidermoid carcinoma. Results: 28.6% and 72.2% of the pleomorphic adenomas and mucoepidermoid carcinomas showed high COX‐2 expression respectively. 35.7% of pleomorphic adenomas and 72.2% of mucoepidermoid carcinomas were tested positive for HuR in the cytoplasm of tumor cells. There was a correlation between a high COX‐2 immunoreactivity and cytoplasmic HuR expression in mucoepidermoid carcinomas but not in pleomorphic adenomas. Conclusion: This study suggests that cytoplasmic HuR is correlated with COX‐2 expression in salivary mucoepidermoid carcinomas. In addition, the immunoreactivity of COX‐2 and cytoplasmic HuR might be used to evaluate the nature of a borderline malignancy in the salivary glands.