Protein tyrosine kinase inhibitors block tumor necrosis factor-induced activation of nuclear factor-kappaB, degradation of IkappaBalpha, nuclear translocation of p65, and subsequent gene expression.
Several inflammatory effects of tumor necrosis factor (TNF) are known to be mediated through activation of a nuclear transcription factor NF-kappaB, but how TNF activates NF-kappaB is incompletely understood. In the present report, we examined the role of protein tyrosine kinases (PTK) in TNF-mediated NF-kappaB activation by using genistein and erbstatin, two potent inhibitors of PTK. The treatment of human myeloid U-937 cells with either inhibitor completely suppressed the TNF-induced NF-kappaB activation in a dose- and time-dependent manner. Suppression correlated with PTK activity, since among the structural analogues of genistein, only an active inhibitor of PTK, quercetin blocked TNF-induced NF-kappaB activation and not daidzein, an inactive inhibitor. Inhibition of NF-kappaB activation was not limited to myeloid cells, as it was observed with T cells and epithelial cells. Both the PTK inhibitors blocked the degradation of IkappaBalpha, the inhibitory subunit of NF-kappaB, and the consequent translocation of the p65 subunit without any significant effect on p50 or on c-Rel. The PTK inhibitors did not interfere with NF-kappaB binding to DNA. The NF-kappaB-dependent CAT reporter gene expression in transient transfection assays was also suppressed by the PTK inhibitors. Both PTK inhibitors abolished TNF-induced activation of N-terminal c-Jun kinase and mitogen-activated protein kinase kinase. Overall, our results suggest that a genistein- and erbstatin-sensitive PTK is involved in the pathway leading to NF-kappaB activation and gene expression by TNF and thus could be used as a target for development of antiinflammatory drugs.
Natarajan
K
K
Department of Molecular Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Manna
S K
SK
Chaturvedi
M M
MM
Aggarwal
B B
BB
D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D020672:I-kappa B Proteins; D007375:Interleukin-1 / Q000494:pharmacology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D019319:Okadaic Acid; D004247:DNA; D019833:Genistein; D015500:Chloramphenicol O-Acetyltransferase; D011505:Protein-Tyrosine Kinases; D013755:Tetradecanoylphorbol Acetate; C048212:erbstatin