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Up-Regulation of Cyclooxygenase-2 Expression in Lymphocytic Thyroiditis and Thyroid Tumors
Significant Correlation With Inducible Nitric Oxide Synthase

Fusako Nose MT, Tsuwa Ichikawa MT, Mutsunori Fujiwara MD, Isao Okayasu MD
DOI: http://dx.doi.org/10.1309/9CCJ-XQ8P-PMFM-M65K 546-551 First published online: 1 April 2002


To cast light on relations of cyclooxygenase-2 (COX-2) expression to lymphocytic thyroiditis and thyroid tumorigenesis, protein levels were immuno-histochemically assessed and compared with inducible nitric oxide synthase (iNOS) in a total of 181 cases: follicular adenoma, 23; well-differentiated papillary carcinoma, 85; poorly differentiated papillary carcinoma, 25; anaplastic carcinoma, 7; and follicular carcinoma, 41. In addition, 72 specimens of normal follicular epithelia and 36 of lymphocytic thyroiditis were used as control samples. Immunohistochemical results were confirmed in 2 cases each of normal thyroid, lymphocytic thyroiditis, and well-differentiated and poorly differentiated papillary carcinoma, by Western blotting assay.

Stepwise increments in overexpression of COX-2 and iNOS were revealed in epithelial cells of lymphocytic thyroiditis, follicular adenoma, and papillary carcinoma; normal thyroid epithelium showed little expression. A significant positive correlation between the 2 enzymes was found with all cases. Enhanced expression of both COX-2 and iNOS suggests important roles in the inflammatory processes underlying lymphocytic thyroiditis and thyroid tumorigenesis.

Key Words:
  • Thyroiditis
  • Thyroid tumorigenesis
  • Cyclooxygenase-2
  • Inducible nitric oxide synthase
  • Nitric oxide
  • Apoptosis