Effect of selective cyclooxygenase 2 inhibitor in TCDD pre-exposed thyroid papillary carcinoma cell line

Background: Cyclooxygenase 2 (COX-2) is related to carcinogenesis and progression of cancer. COX-2 has been detected in thyroid cancer. This suggests that COX-2 inhibitor may be useful to control the growth of thyroid cancer cells as well as the progression of thyroid cancer. Tetrachlo-rodibenzodioxin (TCDD), acting as an infammatory cytokine, directly induces the expression of COX-2. We examine whether TCDD controls the effect of COX-2 inhibitor on thyroid cancer cells. Methods: The effects of TCDD and celecoxib on thyroid papillary carcinoma cell line (SNU790) were examined using cell proliferation and fluorescence-activated cell sorting analysis. Western blot analysis was performed to determine the expressed COX-2 levels and the cell cycle-related proteins. The matrix metalloproteinase-2 (MMP-2) expression and gelatinolytic activity were examined using real time-polymerase chain reaction and zymography. Results: TCDD directly induced the growth of SNU790 and the expression of cyclin D1, cyclin A, cyclin E, p21 and COX-2. Celecoxib suppressed the growth of SNU790 and the expression of cyclin D1 and cyclin E. Celecoxib reduced the MMP-2 expression and the gelatinolytic activity, but those effects were decreased in the SNU790 by either pre-treatment with TCDD or co-treatment with TCDD and celecoxib. Conclusions: Celocoxib effect is directly reduced depending on the exposure to TCDD. TCDD exposure should be considered in the treatment with Celecoxib.