TYROSINE PHOSPHATASE-DEPENDENT TRYROSINE KINASE-INDEPENDENT INDUCTIONOF NUCLEAR FACTOR-KB BY TUMOR-NECROSIS-FACTOR-ALPHA - EFFECTS ON PROSTAGLANDIN ENDOPEROXIDE SYNTHASE-2 MESSENGER-RNA ACCUMULATION/

We previously have demonstrated that tumor necrosis factor-alpha (TNF- alpha) increases prostaglandin endoperoxide synthase-2 (PGHS-2) mRNA a ccumulation and tyrosine phosphorylation in the fibrosarcoma cell line , MCA-101. Tyrosine kinase inhibitor, genistein, and tyrosine phosphat ase inhibitor, phenylarsine oxide (PAO), blocked TNF-alpha-mediated in duction of PGHS-2 mRNA in these cells. Because the PGHS-2 promoter has a nuclear factor-kappa B (NF-kappa B) binding motif, which is importa nt for PGHS-2 gene transcription in some cell types, we have evaluated the effects of tyrosine kinase inhibitors and PAO on TNF-alpha-induce d NF-kappa B activation. TNF-alpha (1 nM) rapidly induced translocatio n of NF-kappa B, an event accompanied by degradation of inhibitory pro tein I kappa B-alpha. N-tosyl-L-phenylalanine chloromethyl ketone (TPC K), a serine protease inhibitor, inhibited I kappa B-alpha degradation and NF-kappa B activation in response to TNF-alpha in a dose-dependen t manner (25, 50, 100 mu M). TPCK also inhibited PGHS-2 mRNA accumulat ion. These data suggest that NF-kappa B contributed to PGHS-2 mRNA acc umulation in MCA-101 cells stimulated with TNF-alpha. PAO (2.4 mu M) c ompletely abolished activation of NF-kappa B and degradation of I kapp a B-alpha induced by TNF-alpha at a concentration that blocked PGHS-2 mRNA accumulation. However, four tyrosine kinase inhibitors, genistein , tyrphostin 47, herbimycin A and erbstatin, failed to block transloca tion of NF-kappa B and degradation of I kappa B-alpha. These data demo nstrate that tyrosine kinase pathways are not required for TNF-alpha-i nduced NF-kappa B activation in MCA-101 cells and suggest that signali ng via these pathways mediates TNF-alpha-induced PGHS-2 mRNA accumulat ion via an NF-kappa B-independent mechanism. Moreover, an upstream tyr osine phosphatase pathway may mediate PGHS-2 mRNA accumulation by TNF- alpha via an NF-kappa B-dependent mechanism.