Showing papers by "Michael B. Sporn published in 2003"

The novel synthetic triterpenoid, CDDO-imidazolide, inhibits inflammatory response and tumor growth in vivo.

Abstract: 1[2-Cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im) is a novel synthetic triterpenoid more potent than its parent compound, 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO), both in vitro and in vivo. CDDO-Im is highly active in suppressing cellular proliferation of human leukemia and breast cancer cell lines (IC(50), approximately 10-30 nM). In U937 leukemia cells, CDDO-Im also induces monocytic differentiation as measured by increased cell surface expression of CD11b and CD36. In each of these assays, CDDO-Im is several-fold more active than CDDO. Although CDDO and CDDO-Im both bind and transactivate peroxisome proliferator-activated receptor (PPAR) gamma, the irreversible PPARgamma antagonist GW9662 does not block the ability of either CDDO or CDDO-Im to induce differentiation; moreover, PPARgamma-null fibroblasts are still sensitive to the growth-suppressive effects of CDDO. Thus, CDDO-Im has significant actions independent of PPARgamma transactivation. In addition, the rexinoid LG100268 and the deltanoid ILX23-7553 (ILX7553) synergize with CDDO and CDDO-Im to induce differentiation. In vivo, CDDO-Im is a potent inhibitor of de novo inducible nitric oxide synthase expression in primary mouse macrophages. Moreover, CDDO-Im inhibits growth of B16 murine melanoma and L1210 murine leukemia cells in vivo. The potent effects of CDDO-Im, both in vitro and in vivo, suggest it should be considered for clinical use.

The Novel Triterpenoid CDDO and its Derivatives Induce Apoptosis by Disruption of Intracellular Redox Balance

Abstract: The novel oleanane triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) induces apoptosis of human leukemia cells by activation of the extrinsic caspase-8 pathway. The mechanisms responsible for the proapoptotic effects of CDDO are unknown. The present studies demonstrate that CDDO activates the c-Jun NH(2)-terminal kinase and p38 mitogen-activated protein kinase in U-937 leukemia cells. The results also show that CDDO activates stress kinases by increasing levels of reactive oxygen species and decreasing intracellular glutathione (GSH) concentrations. Similar findings were obtained with the C-28 methyl ester (CDDO-Me) and C-28 imidazolide ester (CDDO-Im) derivatives. The results also demonstrate that CDDO-induced: (a) stimulation of Jun NH(2)-terminal kinase; (b) activation of caspase-8; (c) loss of mitochondrial transmembrane potential; (d) release of cytochrome c; and (e) cleavage of caspase-3 are blocked by pretreatment with the antioxidant N-acetyl-L-cysteine and GSH but not with cysteine. In concert with these results, CDDO-induced apoptosis is also abrogated by N-acetyl-L-cysteine and GSH. These findings demonstrate that CDDO and its derivatives disrupt intracellular redox balance and thereby induce apoptosis.

Synthetic triterpenoids activate a pathway for apoptosis in AML cells involving downregulation of FLIP and sensitization to TRAIL.

Abstract: Acute myelogenous leukemia (AML) remains a deadly disease for most adult patients, due primarily to the emergence of chemoresistant cells. Defects in apoptosis pathways make important contributions to chemoresistance, suggesting a need to restore apoptosis sensitivity or to identify alternative pathways for apoptosis induction. Triterpenoids represent a class of naturally occurring and synthetic compounds with demonstrated antitumor activity, including 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its methyl ester (CDDO-m). We explored the effects of CDDO and CDDO-m in vitro on established AML cell lines (HL-60, U937, AML-2) and on freshly isolated AML blasts. CDDO and CDDO-m reduced the viability of all AML cell lines tested in a dose-dependent manner, with effective doses for killing 50% of cells (ED50) within 48 h of ∼1 and 0.5 μ M, respectively. CDDO or CDDO-m also induced substantial increases in cell death in five out of 10 samples of primary AML blasts. Cell death induced by CDDO and CDDO-m was attributed to apoptosis, based on characteristic cell morphology and evidence of caspase activation. Immunoblot analysis demonstrated proteolytic processing of caspase-3, -7, and -8, but not caspase-9, suggesting the involvement of the ‘extrinsic’ pathway, linked to apoptosis induction by TNF-family death receptors. Accordingly, CDDO and CDDO-m induced concentration-dependent reductions in the levels of FLIP protein, an endogenous antagonist of caspase-8, without altering the levels of several other apoptosis-relevant proteins. Reductions in FLIP were rapid, detectable within 3 h after exposure of AML cell lines to CDDO or CDDO-m. CDDO and CDDO-m also sensitized two of four leukemia lines to TRAIL, a TNF-family death ligand. The findings suggest that synthetic triterpenoids warrant further investigation in the treatment of AML, alone or in combination with TRAIL or other immune-based therapies.

Synthetic triterpenoids enhance transforming growth factor beta/Smad signaling.

Abstract: We have studied the effects of two new synthetic triterpenoids, 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and its derivative, 1-(2-cyano-3,12-dioxooleana-1,9-dien-28-oyl) imidazole (CDDO-Im), on transforming growth factor (TGF)-β/Smad signaling. These agents, at nanomolar concentrations, increase the expression of TGF-β-dependent genes, such as those for plasminogen activator inhibitor 1 and the type II TGF-β receptor, and they synergize with TGF-β in this regard. They prolong the activation of Smad2 induced by TGF-β and markedly enhance the ability of Smad3 to activate a Smad binding element, CAGA-luciferase. In transfection assays, they reverse the inhibitory effects of Smad7. CDDO and CDDO-Im also enhance Smad signaling in the pathways of two other members of the TGF-β superfamily, namely, activin and bone morphogenetic protein. Finally, these triterpenoids induce expression of the transcriptional coactivator p300-CBP-associated factor and synergize with TGF-β in this regard. These are the first studies to report enhancement of Smad signaling by synthetic triterpenoids and should further their optimal use for applications in prevention or treatment of diseases in which there is aberrant function of TGF-β.

The triterpenoid CDDO inhibits expression of matrix metalloproteinase-1, matrix metalloproteinase-13 and Bcl-3 in primary human chondrocytes

Abstract: A synthetic triterpenoid, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), has been reported to have anti-inflammatory properties and to decrease the interleukin-1 (IL-1)-induced expression of matrix metalloproteinase-1 (MMP-1) and MMP-13. We have shown previously that IL-1 induces expression of the inhibitor of NF-κB (IκB) family member Bcl-3, and that this contributes to MMP-1 expression. To quantify the effects of CDDO on IL-1-induced MMP-1, MMP-13 and Bcl-3 expression, we stimulated the chondrosarcoma cell line SW-1353 and human primary chondrocytes with IL-1, in the presence or absence of CDDO. Harvested RNA was subjected to quantitative real-time reverse-transcriptase polymerase chain reaction. In SW-1353 cells, 300 nM CDDO significantly decreased the induction of MMP-1 and MMP-13 by IL-1. In human primary chondrocytes, 300 nM CDDO inhibited the induction of these genes by IL-1 to an even greater extent. In both cell types, inhibition of MMP-1 required 24 hours of pretreatment with CDDO, whereas MMP-13 could be inhibited when CDDO and IL-1 were added simultaneously to culture. In human primary chondrocytes, IL-1-induced Bcl-3 expression was inhibited when cells were pretreated with CDDO. To determine whether the inhibitory effect of CDDO on MMP worked through inhibition of Bcl-3 gene expression, SW-1353 cells stably transfected with a Bcl-3 expression plasmid were treated with IL-1 and/or CDDO, and MMP gene expression was assayed. Overexpression of Bcl-3 increased MMP-1, but not MMP-13, mRNA levels. Furthermore, overexpressed Bcl-3 could sustain the CDDO-dependent inhibition of IL-1-induced MMP-1 expression. Our data demonstrate that CDDO inhibits IL-1-induced MMP-1 and MMP-13 expression in human chondrocytes. CDDO also inhibits the expression of Bcl-3, an IL-1-responsive gene that preferentially contributes to MMP-1 gene expression.

Efficient synthesis of (−)- and (+)-tricyclic compounds with enone functionalities in rings A and C. A novel class of orally active anti-inflammatory and cancer chemopreventive agents

Abstract: Novel tricyclic compounds with enone functionalities in rings A and C [tricyclic-bis-enone (TBE) compounds] were designed on the basis of the structure of a synthetic triterpenoid, 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO) (1), which is a promising drug candidate for prevention and/or treatment of cancer and inflammatory diseases whose pathogenesis may involve excessive production of nitric oxide (NO) and/or prostaglandins. A series of TBE compounds in racemic form shows high inhibitory activity against production of NO induced by interferon-γ (IFN-γ) in mouse macrophages. One of these compounds, (±)-(4aβ,8aβ,10aα)-1,2,4a,6,8a,9,10,10a-octahydro-1,1,4a,8a-tetramethyl-2,6-dioxophenanthrene-3,7-dicarbonitrile ((±)-3), is orally active at 15 mg kg−1 (single administration) in a preliminary in vivo study using mouse peritoneal inflammation induced by thioglycollate and IFN-γ. Therefore, we desired to synthesize optically active TBE compounds for a comparison of the biological potency of both enantiomers. We now describe the synthesis of both enantiomers of (4aβ,8aβ,10aα)-1,2,4a,6,8a,9,10,10a-octahydro-1,1,4a,8a-tetramethyl-2,6-dioxophenanthrene-3-carbonitrile (2) and 3 from commercially available simple compounds. Interestingly, (+)-3 having the same configuration as the CDDO antipode shows about 10 times higher inhibitory activity than (−)-3 on NO production in mouse macrophages. In contrast, (−)-3 inhibits proliferation of MCF-7 breast cancer cells, whereas (+)-3 does not.

Tricyclic-bis-enone derivatives and methods of use thereof

Abstract: Novel tricyclic-bis-enone derivatives (TBEs) as well as the process for the preparation of such TBEs are provided. Also provided are methods for prevention and/or treatment of cancer, Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotropic lateral sclerosis, rheumatoid arthritis, inflammatory bowel disease, and all other diseases whose pathogenesis is believed to involve excessive production of either nitric oxide (NO) or prostaglandins or the overexpression of iNOS or COX-2 genes or gene products. Further, methods for the synthesis of the TBE compounds of the invention utilize cheap commercially available reagents and are highly cost effective and amenable to scale-up. Additional high efficiency synthetic methods that utilize novel intermediates as well as the synthesis of these intermediates are also provided. Furthermore, the invention also provides methods for designing novel and water-soluble TBEs.