Inducible cyclooxygenase-2 gene expression in the human thyroid epithelial cell line Nthy-ori3-1

Objective: To investigate whether the genes encoding Cyclooxygenase-l and -2 are expressed in thyroid epithelial cells, in vitro. Materials and Methods: COX-1/-2 gene expression was examined in the thyroid epithelial cell line Nthy-ori3-1 using semi-quantitative RT-PCR and Western blot analysis. ELISAs were employed to assess whole cell COX-enzyme activity, PGE(2) and IL-6 formation. Results. In response to IL-1 beta and TNF-alpha combined cells of the thyroid epithelial cell line Nthy-ori3-1 secreted marked amounts of PGE, in a time-dependent fashion. This is attributed to increased levels of COX-2 specific mRNA, increased amounts of COX-2 protein and COX enzyme activity in the absence of detectable COX-1 protein. The inhibition of the induced COX enzyme activity by the selective COX-2 inhibitor NS-398 demonstrated the presence of COX-2 pharmacologically. The expression of the COX-2 gene was also accompanied by a marked induction of IL-6 formation, a well described inflammatory response of thyroid epithelial cells. Conclusions: Our observation presents first evidence that COX-2 gene expression is inducible in thyroid epithelial cells, in vitro, upon stimulation with the pro-inflammatory cytokines IL-1 beta and TNF-alpha. This finding may indicate that thyroid epithelial cells could play an inflammatory controlling role perhaps during auto-immune thyroid diseases.