Activation of NF kappa B is necessary for IL-1 beta-induced cyclooxygenase-2 (COX-2) expression in human gingival fibroblasts

The immediate-early cyclooxygenase-2 (COX-2) gene encodes an inducible pros taglandin synthase enzyme which is implicated in inflammatory and prolifera tive diseases. COX-2 is highly induced during cell activation by various fa ctors, including mitogens, hormones and cytokines. Since pro-inflammatory c ytokine IL-1 beta has been shown to induce prostaglandin E-2 (PGE(2)) relea se in human gingival fibroblasts (HGF), here we analyzed the effect of IL-1 beta on the expression of COX-2 and the activation of NF kappa B in HGF. N orthern hybridization analysis revealed that IL-1 beta (200 pg/ml) increase d the expression of COX-2 mRNA in HGF. The effect of IL-1 beta was abrogate d by herbimycin A, a protein tyrosine kinase inhibitor, and enhanced by ort hovanadate, a protein tyrosine phosphatase inhibitor. IL-1 beta-induced PGE (2) release was blocked by the tyrosine kinase inhibitor and increased by t he tyrosine phosphatase inhibitor. The results of transient transfection as says using chimeric constructs of the human COX-2 promoter (nt -1432 +59) l igated to a luciferase reporter gene indicated that IL-1 beta stimulated th e transcriptional activity 1.5-fold. Gel mobility shift assays with a radio labelled COX-2-NF kappa B oligonucleotide (nts -223 to -214) revealed an in crease in the binding of nuclear proteins from IL-1 beta-stimulated HGF. Th is increase of DNA-protein complex formation induced by IL-1 beta was block ed by herbimycin A and another tyrosine kinase inhibitor, genistein. These results suggest that NF kappa B is an important transcription factor for IL -1 beta-induced COX-2 gene expression, and is involved in inducing COX-2 ge ne transcription through tyrosine phosphorylation in HGF.