okadaic-acid and pregna-4-17-diene-3-16-dione

Guggulsterone, derived from Commiphora mukul and used to treat obesity, diabetes, hyperlipidemia, atherosclerosis, and osteoarthritis, has been recently shown to antagonize the farnesoid X receptor and decrease the expression of bile acid-activated genes. Because activation of NF-kappaB has been closely linked with inflammatory diseases affected by guggulsterone, we postulated that it must modulate NF-kappaB activation. In the present study, we tested this hypothesis by investigating the effect of this steroid on the activation of NF-kappaB induced by inflammatory agents and carcinogens. Guggulsterone suppressed DNA binding of NF-kappaB induced by tumor necrosis factor (TNF), phorbol ester, okadaic acid, cigarette smoke condensate, hydrogen peroxide, and interleukin-1. NF-kappaB activation was not cell type-specific, because both epithelial and leukemia cells were inhibited. Guggulsterone also suppressed constitutive NF-kappaB activation expressed in most tumor cells. Through inhibition of IkappaB kinase activation, this steroid blocked IkappaBalpha phosphorylation and degradation, thus suppressing p65 phosphorylation and nuclear translocation. NF-kappaB-dependent reporter gene transcription induced by TNF, TNFR1, TRADD, TRAF2, NIK, and IKK was also blocked by guggulsterone but without affecting p65-mediated gene transcription. In addition, guggulsterone decreased the expression of gene products involved in anti-apoptosis (IAP1, xIAP, Bfl-1/A1, Bcl-2, cFLIP, and survivin), proliferation (cyclin D1 and c-Myc), and metastasis (MMP-9, COX-2, and VEGF); this correlated with enhancement of apoptosis induced by TNF and chemotherapeutic agents. Overall, our results indicate that guggulsterone suppresses NF-kappaB and NF-kappaB-regulated gene products, which may explain its anti-inflammatory activities.

Topics: Active Transport, Cell Nucleus; Apoptosis; Blotting, Western; Cell Line; Cell Line, Tumor; Cyclooxygenase 2; Dose-Response Relationship, Drug; Enzyme Activation; Gene Expression Regulation; Genes, Reporter; Humans; I-kappa B Proteins; Inflammation; Interleukin-1; Isoenzymes; Jurkat Cells; Luciferases; Membrane Proteins; Models, Chemical; Neoplasm Metastasis; NF-kappa B; NF-KappaB Inhibitor alpha; Okadaic Acid; Phosphorylation; Poly(ADP-ribose) Polymerases; Pregnenediones; Promoter Regions, Genetic; Prostaglandin-Endoperoxide Synthases; Protein Structure, Tertiary; Temperature; Tetradecanoylphorbol Acetate; Transcription, Genetic