Flavopiridol inhibits NF-kappaB activation induced by various carcinogens and inflammatory agents through inhibition of IkappaBalpha kinase and p65 phosphorylation: abrogation of cyclin D1, cyclooxygenase-2, and matrix metalloprotease-9.
Flavopiridol, a synthetic flavone closely related to a compound originally isolated from the stem bark of the native Indian plant Dysoxylum binectariferum, has been found to inhibit cyclin-dependent kinases, induce apoptosis, suppress inflammation, and modulate the immune response. Because several genes in which expression is altered by flavopiridol are regulated by NF-kappaB, we propose that this flavone must affect the activation of NF-kappaB. For this report, we investigated the effect of flavopiridol on NF-kappaB activation by various carcinogens and inflammatory agents. Flavopiridol suppressed tumor necrosis factor (TNF)-activation of NF-kappaB in a dose- and time-dependent manner in several cell types, with optimum inhibition occurring upon treatment of cells with 100 nm flavopiridol for 6 h. This effect was mediated through inhibition of IkappaBalpha kinase, phosphorylation, ubiquitination, and degradation of IkappaBalpha (an inhibitor of NF-kappaB), and suppression of phosphorylation, acylation, and nuclear translocation of the p65 subunit of NF-kappaB. Besides TNF, flavopiridol also suppressed NF-kappaB activated by a carcinogen (cigarette smoke condensate), tumor promoters (phorbol myristate acetate and okadaic acid), and an inflammatory agent (H2O2). TNF-induced NF-kappaB-dependent reporter gene transcription was also suppressed by this flavone. NF-kappaB reporter activity induced by TNF receptor 1, TNF receptor-associated death domain, TNF receptor-associated factor-2, NF-kappaB-inducing kinase, and IkappaBalpha kinase, were all blocked by flavopiridol but not that activated by p65. Furthermore, flavopiridol suppressed TNF-induced activation of Akt. Flavopiridol also inhibited the expression of the TNF-induced NF-kappaB-regulated gene products cyclin D1, cyclooxygenase-2, and matrix metalloproteinase-9. Overall, our results indicated that flavopiridol inhibits activation of NF-kappaB and NF-kappaB-regulated gene expression, which may explain the ability of flavopiridol to suppress inflammation, modulate the immune response, and regulate cell growth.
Takada
Yasunari
Y
Cytokine Research Laboratory, Departments of Bioimmunotherapy, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Aggarwal
Bharat B
BB
D002273:Carcinogens / Q000494:pharmacology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D051550:I-kappa B Kinase; D018836:Inflammation Mediators / Q000494:pharmacology; D019169:Jurkat Cells; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D051996:Transcription Factor RelA; D015533:Transcriptional Activation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D002273:Carcinogens; D004791:Enzyme Inhibitors; D005419:Flavonoids; D018836:Inflammation Mediators; D016328:NF-kappa B; D010880:Piperidines; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C077990:alvocidib; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human