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Cyclooxygenase-2 expression in human thyroid carcinoma and Hashimoto's thyroiditis
Anthony J Cornetta1, John P Russell, Mary Cunnane
1Department of Otolaryngology--Head and Neck Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA. acornetta@earthlink.net
Objectives:
Cyclooxygenases (COX) are enzymes that catalyze the conversion of arachidonic acid to prostaglandins. COX-2, unlike the constitutively expressed COX-1, is an inducible enzyme upregulated during cell proliferation and inflammation. More recently, COX-2 has been implicated in the development of numerous types of epithelial cancers. In addition, COX-2 is highly expressed in several inflammatory diseases. Because of its dual role in inflammation and cancer, we were interested in determining if COX-2 plays a role in the development of human thyroid carcinoma and Hashimoto's thyroiditis, an autoimmune condition frequently associated with thyroid malignancy.
Materials And Methods:
Twenty paraffin-embedded human tissue specimens, including normal, inflammatory, and neoplastic thyroid sections, were analyzed by immunohistochemical staining for expression of human COX-2. In addition, COX-2 protein expression was verified by Western blot in two specimens.
Results:
Immunohistochemical staining confirmed the presence of COX-2 in thyroid epithelial neoplasms, including papillary and follicular carcinomas. Moreover, COX-2 expression was observed in patients with Hashimoto's thyroiditis. COX-2 expression, however, was not observed in normal thyroid tissue, multinodular goiter, or anaplastic carcinoma.
Conclusions:
We have shown that cyclooxygenase-2 is expressed in thyroid carcinoma and thyroid epithelium from patients with Hashimoto's thyroiditis but not in normal thyroid. The expression of COX-2 in both of these thyroid pathologies may provide a basis for the relationship between carcinogenesis and autoimmunity.