Showing papers by "Michael B. Sporn published in 2007"

The tumour microenvironment as a target for chemoprevention

Abstract: New data indicate that primary dysfunction in the tumour microenvironment, in addition to epithelial dysfunction, can be crucial for carcinogenesis. These recent findings make a compelling case for targeting the microenvironment for cancer chemoprevention. We review new insights into the pathophysiology of the microenvironment and new approaches to control it with chemopreventive agents. The microenvironment of a cancer is an integral part of its anatomy and physiology, and functionally, one cannot totally dissociate this microenvironment from what have traditionally been called 'cancer cells'. Finally, we make suggestions for more effective clinical implementation of this knowledge in preventive strategies.

Triterpenoids and rexinoids as multifunctional agents for the prevention and treatment of cancer

Abstract: Synthetic oleanane triterpenoids and rexinoids are two new classes of multifunctional drugs. They are neither conventional cytotoxic agents, nor are they monofunctional drugs that uniquely target single steps in signal transduction pathways. Synthetic oleanane triterpenoids have profound effects on inflammation and the redox state of cells and tissues, as well as being potent anti-proliferative and pro-apoptotic agents. Rexinoids are ligands for the nuclear receptor transcription factors known as retinoid X receptors. Both classes of agents can prevent and treat cancer in experimental animals. These drugs have unique molecular and cellular mechanisms of action and might prove to be synergistic with standard anti-cancer treatments.

Pharmacodynamic characterization of chemopreventive triterpenoids as exceptionally potent inducers of Nrf2-regulated genes

Abstract: Synthetic triterpenoids have been developed, which are potent inducers of cytoprotective enzymes and inhibitors of inflammation, greatly improving on the weak activity of naturally occurring triterpenoids. An imidazolide triterpenoid derivative, 1-[2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im or TP235), has been previously shown to potently protect against hepatic tumorigenesis, acting in part by inducing cytoprotective genes through Keap1-Nrf2-antioxidant response element (ARE) signaling. In these studies, the pharmacodynamic activity of CDDO-Im is characterized in two distinct lines of ARE reporter mice and by measuring increases in Nqo1 transcript levels as a marker of cytoprotective gene induction. Oral administration of CDDO-Im induces ARE-regulated cytoprotective genes in many tissues in the mouse, including liver, lung, kidney, intestines, brain, heart, thymus, and salivary gland. CDDO-Im induces Nqo1 RNA transcripts in some organs at doses as low as 0.3 mumol/kg body weight (orally). A structure activity evaluation of 15 additional triterpenoids (a) confirmed the importance of Michael acceptor groups on both the A and C rings, (b) showed the requirement for a nitrile group at C-2 of the A ring, and (c) indicated that substituents at C-17 dramatically affected pharmacodynamic action in vivo. In addition to CDDO-Im, other triterpenoids, particularly the methyl ester CDDO-Me (TP155) and the dinitrile TP225, are extremely potent inducers of cytoprotective genes in mouse liver, lung, small intestine mucosa, and cerebral cortex. This pharmacodynamic characterization highlights the chemopreventive promise of several synthetic triterpenoids in multiple target organs.

Preclinical evaluation of targeting the Nrf2 pathway by triterpenoids (CDDO-Im and CDDO-Me) for protection from LPS-induced inflammatory response and reactive oxygen species in human peripheral blood mononuclear cells and neutrophils

Abstract: Sepsis is characterized by an inappropriate host immune-inflammatory response and sustained oxidative damage. Nrf2, a bZIP oxidant-responsive transcription factor, regulates a battery of cytoprotective genes including antioxidants and maintains cellular redox homeostasis. Mouse studies have demonstrated a critical role of Nrf2 in improving survival during sepsis. This preclinical ex vivo study using neutrophils and peripheral blood mononuclear cells (PBMCs) as a surrogate cells evaluates the efficacy of CDDO-Im and CDDO-Me [imidazole and methyl ester derivative of 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO)] to activate the Nrf2 pathway and protect from lipopolysaccharide (LPS)-induced inflammatory response in humans. CDDO-Im treatment significantly induced Nrf2–dependent antioxidative genes (HO-1, GCLC, GCLM, and NQO1) in PBMCs isolated from six normal subjects. CDDO-Im increased nuclear accumulation of Nrf2 protein. Pretreatment of PBMC by CDDO-Im significantly attenuated LPS-induced cytoki...

The synthetic triterpenoids CDDO-methyl ester and CDDO-ethyl amide prevent lung cancer induced by vinyl carbamate in A/J mice

Abstract: We report the first use of new synthetic triterpenoids to prevent lung cancer in experimental animals. Female A/J mice were treated with the mutagenic carcinogen vinyl carbamate, which induces adenocarcinoma of the lung in all animals within 16 weeks. If mice were fed either the methyl ester or the ethyl amide derivative of the synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-ME and CDDO-EA, respectively), beginning 1 week after dosing with carcinogen, the number, size, and severity of lung carcinomas were markedly reduced. The mechanisms of action of CDDO-ME and CDDO-EA that are germane to these in vivo findings are the following results shown here in cell culture: (a) suppression of the ability of IFN-gamma to induce de novo formation of nitric oxide synthase in a macrophage-like cell line RAW264.7, (b) induction of heme oxygenase-1 in these RAW cells, and (c) suppression of phosphorylation of the transcription factor signal transducers and activators of transcription 3 as well as induction of apoptosis in human lung cancer cell lines.

Novel semisynthetic analogues of betulinic acid with diverse cytoprotective, antiproliferative, and proapoptotic activities.

Abstract: Betulinic acid (BA), a pentacyclic triterpene isolated from birch bark and other plants, selectively inhibits the growth of human cancer cell lines. However, the poor potency of BA hinders its clinical development, despite a lack of toxicity in animal studies even at high concentrations. Here, we describe six BA derivatives that are markedly more potent than BA for inhibiting inducible nitric oxide synthase, activating phase 2 cytoprotective enzymes, and inducing apoptosis in cancer cells and in Bax/Bak−/− fibroblasts, which lack two key proteins involved in the intrinsic, mitochondrial-dependent apoptotic pathway. Notably, adding a cyano-enone functionality in the A ring of BA enhanced its cytoprotective properties, but replacing the cyano group with a methoxycarbonyl strikingly increased potency in the apoptosis assays. Higher plasma and tissue levels were obtained with the new BA analogues, especially CBA-Im [1-(2-cyano-3-oxolupa-1,20(29)-dien-28-oyl)imidazole], compared with BA itself and at concentrations that were active in vitro . These results suggest that BA is a useful platform for drug development, and the enhanced potency and varied biological activities of CBA-Im make it a promising candidate for further chemoprevention or chemotherapeutic studies. [Mol Cancer Ther 2007;6(7):2113–9]

The synthetic oleanane triterpenoid, CDDO-methyl ester, is a potent antiangiogenic agent

Abstract: We show that the synthetic oleanane triterpenoid, CDDO-methyl ester (CDDO-Me; methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate) is an effective agent for suppressing angiogenesis, both in cell culture and in vivo. The potency of CDDO-Me is particularly striking when dosed in vivo to inhibit the angiogenic effects of vascular endothelial growth factor and tumor necrosis factor-alpha in Matrigel sponge assays; activity is seen at i.p. doses of CDDO-Me as low as 0.003 mg/kg of body weight. If the Matrigel sponges are impregnated with CDDO-Me just before implantation in the mice, picomolar doses of CDDO-Me will suppress angiogenesis. CDDO-Me also inhibits growth of endothelial cells in monolayer cultures and suppresses neovascular morphogenesis in three-dimensional cultures, but significantly higher doses (50-200 nmol/L) are required. We also show antiangiogenic effects of CDDO-Me on xenografts of Kaposi's sarcoma cells in immunocompromised mice, using CD31 as a marker. Several known individual molecular targets of CDDO-Me and related triterpenoids that are relevant to all of these findings include nuclear factor-kappaB signaling, signal transducers and activators of transcription signaling, and transforming growth factor-beta signaling, as well as Keap1, the endogenous inhibitor of the transcription factor Nrf2. However, the particularly potent antiangiogenic activity seen in vivo in the present experiments suggest that CDDO-Me, as an angioprevention agent, may be interacting with an entire network of molecular and cellular targets, rather than at a single molecular locus or in a single-cell type.

c-FLIP downregulation contributes to apoptosis induction by the novel synthetic triterpenoid methyl-2-cyano-3, 12-dioxooleana-1, 9-dien-28-oate (CDDO-Me) in human lung cancer cells.

Abstract: The novel synthetic triterpenoid methyl-2-cyano-3, 12-dioxooleana-1, 9-dien-28-oate (CDDO-Me) induces apoptosis of cancer cells, enhances tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, and exhibits potent anticancer activity in animal models with a favorable pharmacokinetic profile. Thus, CDDO-Me is being tested in Phase I clinical trials. In an effort to understand the mechanism by which CDDO-Me induces apoptosis, particularly in human lung cancer cells, we previously demonstrated that CDDO-Me induces apoptosis involving c-Jun N-terminal kinase (JNK)-dependent upregulation of death receptor 5 (DR5) expression. In the current work, we determined the modulatory effects of CDDO-Me on the levels of c-FLIP, a major inhibitor of death receptor-mediated caspase-8 activation, and its impact on CDDO-Me-induced apoptosis and enhancement of TRAIL-induced apoptosis in human lung cancer cells. CDDO-Me rapidly and potently decreased c-FLIP levels including both long (FLIP(L)) and short (FLIP(S)) forms of c-FLIP in multiple human lung cancer cell lines. The presence of the proteasome inhibitor MG132, but not the JNK inhibitor SP600125, prevented CDDO-Me-induced c-FLIP reduction. Moreover, CDDO-Me increased ubiquitination of c-FLIP. Thus, CDDO-Me induces ubiquitin/proteasome-dependent c-FLIP degradation independently of JNK activation. Importantly, overexpression of c-FLIP (e.g., FLIP(L)) protected cells not only from CDDO-Me-induced apoptosis, but also from induction of apoptosis by the combination of CDDO-Me and TRAIL. Accordingly, silencing of c-FLIP with c-FLIP siRNA sensitized cancer cells to CDDO-Me. Collectively, these results indicate that c-FLIP downregulation contributes to CDDO-Me-initiated apoptosis and also to enhancement of TRAIL-induced apoptosis by CDDO-Me.

Therapeutic compounds and methods of use

Abstract: Compounds and methods useful for chemopreventative treatment of diseases such as cancer, Alzheimer's disease, Parkinson's disease, inflammatory bowel diseases, and multiple sclerosis.

Novel tricyclic compounds having acetylene groups at C-8a and cyano enones in rings A and C: highly potent anti-inflammatory and cytoprotective agents.

Abstract: Novel C-8a functionalized tricyclic compounds having cyano enones in rings A and C have been synthesized and biologically evaluated. Among them, compounds with acetylene groups at C-8a show extremely high potency in in vitro and in vivo bioassays for anti-inflammatory and cytoprotective activities. Both in vitro and in vivo potencies are markedly higher than those of 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO), which is being evaluated as an anticancer drug in phase I clinical trials.

Platforms and networks in triterpenoid pharmacology

Abstract: Using the pentacyclic, naturally occurring triterpenoids, oleanolic, ursolic, and betulinic acids, as starting materials, we have developed a new series of multifunctional drugs for potential clinical use. These agents have anti-inflammatory, anti-oxidative, anti-proliferative, pro-apoptotic, and differentiating activities. Two synthetic oleanane triterpenoids, 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO) and its C-28 methyl ester (CDDO-Me), are presently in Phase I clinical trials in cancer patients. Three themes are emphasized in this review: (1) The importance of the unique structures of the triterpenoid platforms that have been used as a start for new synthesis; (2) The concept that these new drugs interact with entire physiological networks, rather than solely with single molecular targets; and (3) The coupling in real time between the triterpenoid platforms and the physiological networks with which they interact, as seen in the reversibility of the Michael reactions, which mediate their activity. We suggest that further development of such new, multifunctional drugs will most likely occur in the more flexible environment of small biotech or pharmaceutical companies. Drug Dev Res 68:174–182, 2007. © 2007 Wiley-Liss, Inc.

Synthetic triterpenoids and tricyclic-bis-enones for use in stimulating bone and cartilage growth

Abstract: The present invention concerns methods for stimulating the growth and repair of bone and cartilage using synthetic triterpenoids and tricyclic-bis-enones. Examples of suitable triterpenoids include CDDO, CDDO-Me, CDDO-Im, and CDDO-Ethylamide. Examples of tricyclic-bis-enones include TBE-31 and TBE-34.

Synthesis and biological activities of new tricyclic-bis-enones (tbes)

Abstract: This invention describes novel tricyclic-bis-enone derivatives (TBEs), such as TBE-31, TBE-34, TBE-45 and water-soluble TBEs. The methods of preparing these compounds are also disclosed. The inventors demonstrate the ability of these new TBEs to inhibit proliferation of human myeloma cells, inhibit the induction of iNOS in cells stimulated with interferon-γ, induce heme oxygenase-1 (HO-1), induce CD11b expression—a leukemia differentiation marker, inhibit proliferation of leukemia cells, induce apoptosis in human lung cancer, and induce apoptosis in other cancerous cells. The TBEs of this invention are expected to be useful agents for the treatment and prevention of many diseases, including cancer, neurological disorders, inflammation, and pathologies involving oxidative stress.

A New Rexinoid, NRX194204, Prevents Carcinogenesis in Both the Lung and Mammary Gland

Abstract: Purpose: We evaluated the anti-inflammatory and growth-inhibitory properties of the novel rexinoid NRX194204 (4204) in vitro and then tested its ability to prevent and/or treat experimental lung and estrogen receptor (ER)–negative breast cancer in vivo . Experimental Design: In cell culture studies, we measured the ability of 4204 to block the effects of lipopolysaccharide and induce apoptosis. For the lung cancer prevention studies, A/J mice were injected with the carcinogen vinyl carbamate and then fed 4204 (30-60 mg/kg diet) for 15 weeks, beginning 1 week after the administration of the carcinogen. For breast cancer prevention studies, mouse mammary tumor virus-neu mice were fed control diet or 4204 (20 mg/kg diet) for 50 weeks; for treatment, tumors at least 32 mm 3 in size were allowed to form, and then mice were fed control diet or 4204 (60 mg/kg diet) for 4 weeks. Results: Low nanomolar concentrations of 4204 blocked the ability of lipopolysaccharide and tumor necrosis factor-α to induce the release of nitric oxide and interleukin 6 and the degradation of IKBα in RAW264.7 macrophage-like cells. In the A/J mouse model of lung cancer, 4204 significantly ( P Conclusions: The combined anti-inflammatory and anticarcinogenic actions of 4204 suggest that it is a promising new rexinoid that should be considered for future clinical trials.

The synthetic triterpenoid TP-222 inhibits RANKL stimulation of osteoclastogenesis and matrix metalloproteinase-9 expression

Abstract: OBJECTIVE: Receptor activator of nuclear factor-kappaB ligand (RANKL) promotes osteoclast differentiation from monocyte precursors by inducing a cohort of genes, including tartrate-resistant acid phosphatase (TRAP) and matrix metalloproteinase-9 (MMP-9). A family of synthetic triterpenoids with antiinflammatory and pro-apoptotic properties was described to modulate differentiation in monocytic cell lineages. We therefore investigated the ability of the potent and bioavailable synthetic triterpenoid TP-222 to inhibit RANKL-induced osteoclast formation and MMP-9 expression from monocytic precursor cells. METHODS: Osteoclast formation was assayed by staining for TRAP-positive multinucleated cells. MMP-9 expression was measured by quantitative RT-PCR, Western blot, immunohistochemistry, and gel zymography. In vivo effects of TP-222 were assessed by daily intraperitoneal injection of 4-week-old mice for 7 days followed by measurement of osteoclast number and MMP-9 expression at the cartilage/bone junction of the epiphyseal growth plate. RESULTS: RANKL promoted and TP-222 (300 nM) inhibited osteoclast formation in cultures of RAW264.7 cells or bone marrow-derived monocytes. RANKL also induced MMP-9 expression in RAW264.7 cells and this was reduced by concurrent or subsequent addition of TP-222. TP-222 treatment significantly reduced the mean number of osteoclasts present at the cartilage/bone interface compared to vehicle-injected control mice. Morphometric analyses of tissue sections showed that TP-222 treatment reduced the amount of immunoreactive MMP-9 present in both mononucleated pre-osteoclasts and osteoclasts. CONCLUSION: Our data demonstrate that TP-222 inhibits osteoclast formation and MMP-9 expression in vitro and in vivo, and suggest that triterpenoids may be useful compounds for modulating bone resorption diseases.

A New Tumor Suppressor Gene, Selective for Lung Cancer

Abstract: sion of this gene occurred in human lung (among more than a dozen human tissues examined), and, moreover, the important observation was made that GPRC5A mRNA was expressed at only very low levels in human lung cancer cells (three of five head and neck squamous cell carcinoma and four of six non – small cell lung cancer cell lines). The authors hypothesized that this decrease in mRNA expression might be associated with the malignant transformation of airway epithelium. The article by Tao et al. ( 2 ) in the current issue of the Journal now provides excellent, detailed experimental evidence for this hypothesis. The key experimental tool in this article has been the use of mice (B6/129sv) in which the Gprc5a gene has been knocked out by homologous recombination. The Lotan group is not the fi rst to have used knockout technology to study the biology of Gprc5a in the mouse lung. Thus, in an elegant study, Xu et al. ( 3 ) used classical recombinant technology to show that Gprc5a is expressed abundantly and specifi cally in the lung during embryonic development and in adult mice. These authors found that the onset of Gprc5a expression in the embryonic mouse lung coincided with the onset of differentiation in the lung, and they suggested that this gene plays an important role in lung maturation and differentiation. The loss of such a differentiating function during carcinogenesis is in accord with classical concepts of cancer as a disease of differentiation ( 4 , 5 ). However, most notably, the lungs of 3-month-old Gprc5a − / − mice appeared histologically normal in spite of the fact that this gene is expressed at high levels in Gprc5a +/+ mice of this age, in both type I and type II pneumocytes. The reason for this lack of phenotype at 3 months of age is unclear, but the authors suggest that the expression of a related gene that regulates G protein signaling (Raig3, also known as Gprc5c) may