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Impact Statement: The success rate for cancer drugs which enter into phase 1 clinical trials is utterly less. Why the vast majority of drugs fail is not understood but suggests that pre-clinical studies are not adequate for human diseases. In 1975, as per the Tufts Center for the Study of Drug Development, pharmaceutical industries expended 100 million dollars for research and development of the average FDA approved drug. By 2005, this figure had more than quadrupled, to $1.3 billion. In order to recover their high and risky investment cost, pharmaceutical companies charge more for their products. However, there exists no correlation between drug development cost and actual sale of the drug. This high drug development cost could be due to the reason that all patients might not respond to the drug. Hence, a given drug has to be tested in large number of patients to show drug benefits and obtain significant results.

Background: While the anti-inflammatory and anticancer potential of curcumin, which is derived from turmeric (Curcuma longa), has been studied extensively, very little is known about Calebin A, another novel compound from the same source., Purpose: To determine whether Calebin A exhibits anti-inflammatory and anticancer potential., Methods: We examined the anti-inflammatory potential of Calebin A by DNA binding of NF-κB. Anticancer properties of Calebin were determined by MTT and FACS analysis and NF-κB regulated expression of proteins was assessed by western blotting., Results: Calebin A suppressed NF-κB activation induced by various stimuli. This inhibition of NF-κB activation was mediated through the suppression of direct binding of NF-κB/p65 to the DNA. This inhibitory effect was reversed by a reducing agent, and mutation of the Cys38 of p65 to serine abolished the effect of Calebin A on this binding. Suppression of NF-κB activation by Calebin A resulted in the down-regulation of the expression of proteins involved in tumor cell survival, proliferation, inflammation, and metastasis. Furthermore, Calebin A inhibited proliferation and induced apoptosis in a wide variety of tumor cells, as examined by various assays. It enhanced apoptosis induced by chemotherapeutic agents., Conclusion: Our results demonstrate that Calebin A inhibits NF-κB activation pathway through interaction with p65 and potentiates apoptosis in cancer cells; thus, it has potential in the treatment of cancer. However, further in vivo studies are warranted to define its anti-inflammatory and anticancer potential., (Published by Elsevier GmbH.)

Curcumin, a component of a spice native to India, was first isolated in 1815 by Vogel and Pelletier from the rhizomes of Curcuma longa (turmeric) and, subsequently, the chemical structure of curcumin as diferuloylmethane was reported by Milobedzka et al. [(1910) 43., 2163-2170]. Since then, this polyphenol has been shown to exhibit antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, and antifungal activities. The current review primarily focuses on the anticancer potential of curcumin through the modulation of multiple cell signaling pathways. Curcumin modulates diverse transcription factors, inflammatory cytokines, enzymes, kinases, growth factors, receptors, and various other proteins with an affinity ranging from the pM to the mM range. Furthermore, curcumin effectively regulates tumor cell growth via modulation of numerous cell signaling pathways and potentiates the effect of chemotherapeutic agents and radiation against cancer. Curcumin can interact with most of the targets that are modulated by FDA-approved drugs for cancer therapy. The focus of this review is to discuss the molecular basis for the anticancer activities of curcumin based on preclinical and clinical findings., (© 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.)

Novel drug development leading to final approval by the US FDA can cost as much as two billion dollars. Why the cost of novel drug discovery is so expensive is unclear, but high failure rates at the preclinical and clinical stages are major reasons. Although therapies targeting a given cell signaling pathway or a protein have become prominent in drug discovery, such treatments have done little in preventing or treating any disease alone because most chronic diseases have been found to be multigenic. A review of the discovery of numerous drugs currently being used for various diseases including cancer, diabetes, cardiovascular, pulmonary, and autoimmune diseases indicates that serendipity has played a major role in the discovery. In this review we provide evidence that rational drug discovery and targeted therapies have minimal roles in drug discovery, and that serendipity and coincidence have played and continue to play major roles. The primary focus in this review is on cancer-related drug discovery., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Selective killing of cancer cells is one of the major goals of cancer therapy. Although chemotherapeutic agents are being used for cancer treatment, they lack selectivity toward tumor cells. Among the six different death receptors (DRs) identified to date, DR4 and DR5 are selectively expressed on cancer cells. Therefore, unlike chemotherapeutic agents, these receptors can potentially mediate selective killing of tumor cells. In this review we outline various nutraceuticals derived from 'Mother Nature' that can upregulate DRs and thus potentiate apoptosis. These nutraceuticals increase tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis of cancer cells through different mechanisms. First, nutraceuticals have been found to induce DRs through the upregulation of various signaling molecules. Second, nutraceuticals can downregulate tumor cell-survival pathways. Third, nutraceuticals alone have been found to activate cell-death pathways. Although both TRAIL and agonistic antibodies against DR4 and DR5 are in clinical trials, combination with nutraceuticals is likely to boost their anticancer potential., (Published by Elsevier Ltd.)

In a search of new compounds active against cancer, synthesis of a series of C-5 curcumin analogues was carried out. The new compounds demonstrated good cytotoxicity against chronic myeloid leukemia (KBM5) and colon cancer (HCT116) cell lines. Further, these compounds were found to have better potential to inhibit TNF-α-induced NF-κB activation in comparison to curcumin, which show their potential to act as anti-inflammatory agents. Some compounds were found to show higher cytotoxicity against cancer cell lines in comparison to curcumin used as standard.

Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has shown efficacy in a phase 2 clinical trial, development of resistance to TRAIL by tumor cells is a major roadblock. We investigated whether azadirone, a limonoidal tetranortriterpene, can sensitize human tumor cells to TRAIL. Results indicate that azadirone sensitized cancer cells to TRAIL. The limonoid induced expression of death receptor (DR) 5 and DR4 but did not affect expression of decoy receptors in cancer cells. The induction of DRs was mediated through activation of ERK and through up-regulation of a transcription factor CCAAT enhancer-binding protein homologous protein (CHOP) as silencing of these signaling molecules abrogated the effect of azadirone. These effects of azadirone were cancer cell-specific. The CHOP binding site on the DR5 gene was required for induction of DR5 by azadirone. Up-regulation of DRs was mediated through the generation of reactive oxygen species (ROS) as ROS scavengers reduced the effect of azadirone on ERK activation, CHOP up-regulation, DR induction, and TRAIL sensitization. The induction of DRs by this limonoid was independent of p53, but sensitization to TRAIL was p53-dependent. The limonoid down-regulated the expression of cell survival proteins and up-regulated the proapoptotic proteins. The combination of azadirone with TRAIL was found to be additive at concentrations lower than IC50, whereas at higher concentrations, the combination was synergistic. Overall, this study indicates that azadirone can sensitize cancer cells to TRAIL through ROS-ERK-CHOP-mediated up-regulation of DR5 and DR4 signaling, down-regulation of cell survival proteins, and up-regulation of proapoptotic proteins.

Progressively increasing failure rates, high cost, poor bioavailability, poor safety, limited efficacy, and a lengthy design and testing process associated with cancer drug development have necessitated alternative approaches to drug discovery. Exploring established non-cancer drugs for anticancer activity provides an opportunity rapidly to advance therapeutic strategies into clinical trials. The impetus for development of cancer therapeutics from non-cancer drugs stems from the fact that different diseases share common molecular pathways and targets in the cell. Common molecular origins of diverse diseases have been discovered through advancements in genomics, proteomics, and informatics technologies, as well as through the development of analytical tools that allow researchers simultaneously to screen large numbers of existing drugs against a particular disease target. Thus, drugs originally identified as antitussive, sedative, analgesic, antipyretic, antiarthritic, anesthetic, antidiabetic, muscle relaxant, immunosuppressant, antibiotic, antiepileptic, cardioprotective, antihypertensive, erectile function enhancing, or angina relieving are being repurposed for cancer. This review describes the repurposing of these drugs for cancer treatment., (Published by Elsevier Ltd.)

Turmeric, a dried powder derived from the rhizome of Curcuma longa, has been used for centuries in certain parts of the world and has been linked to numerous biological activities including antioxidant, anti-inflammatory, anticancer, antigrowth, anti-arthritic, anti-atherosclerotic, antidepressant, anti-aging, antidiabetic, antimicrobial, wound healing, and memory-enhancing activities. One component of turmeric is curcumin, which has been extensively studied, as indicated by more than 5600 citations, most of which have appeared within the past decade. Recent research has identified numerous chemical entities from turmeric other than curcumin. It is unclear whether all of the activities ascribed to turmeric are due to curcumin or whether other compounds in turmeric can manifest these activities uniquely, additively, or synergistically with curcumin. However, studies have indicated that turmeric oil, present in turmeric, can enhance the bioavailability of curcumin. Studies over the past decade have indicated that curcumin-free turmeric (CFT) components possess numerous biological activities including anti-inflammatory, anticancer, and antidiabetic activities. Elemene derived from turmeric is approved in China for the treatment of cancer. The current review focuses on the anticancer and anti-inflammatory activities exhibited by CFT and by some individual components of turmeric, including turmerin, turmerone, elemene, furanodiene, curdione, bisacurone, cyclocurcumin, calebin A, and germacrone., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Success of cancer vaccination is strongly hampered by immune suppression in the tumor microenvironment (TME). Interleukin (IL)-6 is particularly and highly produced by triple-negative breast cancer (TNBC) cells, and has been considered as an important contributor to immune suppression in the TME. Therefore, we hypothesized that IL-6 reduction may improve efficacy of vaccination against TNBC cancer through improved T-cell responses. To prove this hypothesis, we investigated the effect of curcumin, an inhibitor of IL-6 production, on vaccination of a highly attenuated Listeria monocytogenes (Listeria(at)), encoding tumor-associated antigens (TAA) Mage-b in a TNBC model 4T1. Two therapeutic vaccination strategies with Listeria(at)-Mage-b and curcumin were tested. The first immunization strategy involved all Listeria(at)-Mage-b vaccinations and curcumin after tumor development. As curcumin has been consumed all over the world, the second immunization strategy involved curcumin before and all therapeutic vaccinations with Listeria(at)-Mage-b after tumor development. Here, we demonstrate that curcumin significantly improves therapeutic efficacy of Listeria(at)-Mage-b with both immunization strategies particularly against metastases in a TNBC model (4T1). The combination therapy was slightly but significantly more effective against the metastases when curcumin was administered before compared to after tumor development. With curcumin before tumor development in the combination therapy, the production of IL-6 was significantly decreased and IL-12 increased by myeloid-derived suppressor cells (MDSC), in correlation with improved CD4 and CD8 T-cell responses in blood. Our study suggests that curcumin improves the efficacy of Listeria(at)-Mage-b vaccine against metastases in TNBC model 4T1 through reversal of tumor-induced immune suppression.

The major goal of cancer drug discovery is to find an agent that is safe and affordable, yet effective against cancer. Here we show that morin (3,5,7,2',4'-pentahydroxyflavone) has potential against cancer cells through suppression of the signal transducer and activator of transcription 3 (STAT3) pathway, which is closely linked to the transformation, survival, proliferation, and metastasis of cancer. We found that morin completely suppressed inducible and constitutively activated STAT3 and blocked the nuclear translocation of STAT3 and its DNA binding in multiple myeloma and head and neck squamous carcinoma cells. Morin inhibited activated Src, JAK-1, and JAK-2, all of which are linked to STAT3 activation, while up-regulating a protein inhibitor of activated STAT3, PIAS3. Pervanadate reversed the effects of morin on STAT3 phosphorylation, indicating the role of a protein tyrosine phosphatase. Furthermore, morin induced SHP1 expression at both the mRNA and protein levels, and silencing of SHP1 abrogated the effect of morin on STAT3 phosphorylation, indicating that morin mediates its effects on STAT3 through SHP1. Suppression of STAT3 correlated with the down-regulation of various gene products linked to tumor survival, proliferation, and angiogenesis and led to sensitization of tumor cells to thalidomide and bortezomib. Comparing the activities of morin with those of four structurally related flavonols demonstrated the importance of hydroxyl groups in the B ring in inhibiting STAT3 activation. These findings suggest that morin suppresses the STAT3 pathway, leading to the down-regulation of STAT3-dependent gene expression and chemosensitization of tumor cells., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Curcumin, an active polyphenol of the golden spice turmeric, is a highly pleiotropic molecule with the potential to modulate the biological activity of a number of signaling molecules. Traditionally, this polyphenol has been used in Asian countries to treat such human ailments as acne, psoriasis, dermatitis, and rash. Recent studies have indicated that curcumin can target newly identified signaling pathways including those associated with microRNA, cancer stem cells, and autophagy. Extensive research from preclinical and clinical studies has delineated the molecular basis for the pharmaceutical uses of this polyphenol against cancer, pulmonary diseases, neurological diseases, liver diseases, metabolic diseases, autoimmune diseases, cardiovascular diseases, and numerous other chronic diseases. Multiple studies have indicated the safety and efficacy of curcumin in numerous animals including rodents, monkeys, horses, rabbits, and cats and have provided a solid basis for evaluating its safety and efficacy in humans. To date, more than 65 human clinical trials of curcumin, which included more than 1000 patients, have been completed, and as many as 35 clinical trials are underway. Curcumin is now used as a supplement in several countries including the United States, India, Japan, Korea, Thailand, China, Turkey, South Africa, Nepal, and Pakistan. In this review, we provide evidence for the pharmaceutical uses of curcumin for various diseases., (Copyright © 2013 International Union of Biochemistry and Molecular Biology, Inc.)

Colorectal cancer (CRC) is a complex disease with genetic and epigenetic alterations in many key oncogenes and tumor suppressor genes. The active principle of a gum resin from Boswellia serrata, 3-acetyl-11-keto-β-boswellic acid (AKBA), has recently gained attention as a chemopreventive compound due to its ability to target key oncogenic proteins such as 5-lipoxygenase and nuclear factor-kappaB. AKBA has been shown to inhibit the growth of CRC cells; however, the precise molecular mechanisms underlying its anticancer activities in CRC remain unclear. We hypothesized that boswellic acids may achieve their chemopreventive effects by modulating specific microRNA (miRNA) pathways. We found that AKBA significantly up-regulated expression of the let-7 and miR-200 families in various CRC cell lines. Both let-7 and miR-200 are putative tumor-suppressive miRNAs. AKBA modulated the expression of several downstream targets of the let-7 and miR-200 families, such as CDK6, vimentin and E-cadherin. These data were further strengthened by miRNA knockdown studies, which revealed that inhibition of let-7i facilitated enhanced cancer cell proliferation, migration and invasion. In addition, AKBA also induced similar modulation of the let-7 and miR-200 downstream genes in CRC tumors orthotopically implanted in nude mice. These results indicate that AKBA-induced antitumor effects in CRC occur, at least partly through the up-regulation of specific miRNA pathways. Our data provide novel evidence that anticancer effects of boswellic acids are due in part to their ability to regulate cellular epigenetic machinery and further highlight the promise for this phytochemical in the preventative and therapeutic applications of CRC.

Mantle cell lymphoma (MCL) is an incurable, aggressive histo-type of B-cell non-Hodgkin lymphoma associated with both high relapsed rates and relatively short survival. Because MCL over-expresses receptors for B lymphocyte stimulator (BLyS) and displays constitutively active NF-κB, agents targeting these pathways may be of therapeutic relevance in this disease. To investigate the potential clinical use of the rGel/BLyS fusion toxin in combination with bortezomib, we evaluated this fusion toxin for its ability to inhibit MCL growth in severe combined immunodeficiency (SCID) xenograft model. Compared with PBS-treated mice, mice treated with this fusion toxin prolonged both median (84 days vs. 125 days) and overall survival (0% vs. 40%) (p=0.0027). Compared with bortezomib alone-treated mice, mice treated with rGel/BLyS plus bortezomib showed significantly increased median (91 days vs. 158 days) and overall survival (0% vs. 20%) (p=0.0127). Histopathologic analysis of peritoneal intestinal mesentery from MCL-SCID mice showed no demonstrable microscopic lymphomatous involvement at 225 days after treatment with rGel/BLyS. Combination treatment resulted in a synergistic growth inhibition, down-regulation of NF-κB DNA-binding activity, inhibition of cyclin D1, Bcl-x(L), p-Akt, Akt, p-mTOR, and p-Bad, up-regulation of Bax, and induction of cellular apoptosis. Our findings demonstrate that rGel/BLyS is an effective therapeutic agent for both primary and salvage treatment of aggressive MCL expressing constitutively active NF-κB and BLyS receptors and may be an excellent candidate for clinical development., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Scope: The incidence of cancer is significantly lower in regions where turmeric is heavily consumed. Whether lower cancer incidence is due to turmeric was investigated by examining its effects on tumor cell proliferation, on pro-inflammatory transcription factors NF-κB and STAT3, and on associated gene products., Methods and Results: Cell proliferation and cell cytotoxicity were measured by the MTT method, NF-κB activity by EMSA, protein expression by Western blot analysis, ROS generation by FACS analysis, and osteoclastogenesis by TRAP assay. Turmeric inhibited NF-κB activation and down-regulated NF-κB-regulated gene products linked to survival (Bcl-2, cFLIP, XIAP, and cIAP1), proliferation (cyclin D1 and c-Myc), and metastasis (CXCR4) of cancer cells. The spice suppressed the activation of STAT3, and induced the death receptors (DR)4 and DR5. Turmeric enhanced the production of ROS, and suppressed the growth of tumor cell lines. Furthermore, turmeric sensitized the tumor cells to chemotherapeutic agents capecitabine and taxol. Turmeric was found to be more potent than pure curcumin for cell growth inhibition. Turmeric also inhibited NF-κB activation induced by RANKL that correlated with the suppression of osteoclastogenesis., Conclusion: Our results indicate that turmeric can effectively block the proliferation of tumor cells through the suppression of NF-κB and STAT3 pathways., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cholangiocarcinoma (CCA) is a tumor with poor prognosis that is resistant to all currently available treatments. Whether curcumin, a nutraceutical derived from turmeric (Curcuma longa), has potential therapeutic activity against human CCA was investigated using three CCA cell lines (KKU100, KKU-M156 and KKU-M213). Examination of mitochondrial dehydrogenase activity, phosphatidylserine externalization, esterase staining, caspase activation and poly-adenosine diphosphate ribose polymerase cleavage demonstrated that curcumin inhibited proliferation of and induced apoptosis in these biliary cancer cells. Colony-formation assay confirmed the growth-inhibitory effect of curcumin on CCA cells. When examined for the mechanism, curcumin was found to activate multiple cell signaling pathways in these cells. First, all CCA cells exhibited constitutively active nuclear factor (NF)-κB, and treatment with curcumin abolished this activation as indicated by DNA binding, nuclear translocation and p65 phosphorylation. Second, curcumin suppressed activation of signal transducer and activator of transcription-3 as indicated by decreased phosphorylation at both tyrosine(705) and serine(727) and inhibition of janus kinase-1 phosphorylation. Third, curcumin induced expression of peroxisome proliferator-activated receptor gamma. Fourth, curcumin upregulated death receptors, DR4 and DR5. Fifth, curcumin suppressed the Akt activation pathway. Sixth, curcumin inhibited expression of cell survival proteins such as B-cell lymphoma-2, B-cell leukemia protein xL, X-linked inhibitor of apoptosis protein, c-FLIP, cellular inhibitor of apoptosis protein (cIAP)-1, cIAP-2 and survivin and proteins linked to cell proliferation, such as cyclin D1 and c-Myc. Seventh, the growth inhibitory effect of curcumin was enhanced in the IκB kinase-deficient cells, the enzyme required for nuclear factor-kappaB activation. Overall, our results indicate that curcumin mediates its antiproliferative and apoptotic effects through activation of multiple cell signaling pathways, and thus, its activity against CCA should be further investigated.

Purpose: Curcumin, a plant-derived natural polyphenol, could be a promising anti-cancer drug and shows synergic effects with cytotoxic agents. We evaluated the safety and feasibility of combination therapy using curcumin with gemcitabine-based chemotherapy., Methods: Gemcitabine-resistant patients with pancreatic cancer received 8 g oral curcumin daily in combination with gemcitabine-based chemotherapy. The primary endpoint was safety for phase I and feasibility of oral curcumin for phase II study., Results: Twenty-one patients were enrolled. No dose-limiting toxicities were observed in the phase I study and oral curcumin 8 g/day was selected as the recommended dose for the phase II study. No patients were withdrawn from this study because of the intolerability of curcumin, which met the primary endpoint of the phase II study, and the median compliance rate of oral curcumin was 100% (Range 79-100%). Median survival time after initiation of curcumin was 161 days (95% confidence interval 109-223 days) and 1-year survival rate was 19% (4.4-41.4%). Plasma curcumin levels ranged from 29 to 412 ng/ml in five patients tested., Conclusions: Combination therapy using 8 g oral curcumin daily with gemcitabine-based chemotherapy was safe and feasible in patients with pancreatic cancer and warrants further investigation into its efficacy.

Regions along the Mediterranean and in southern Asia have lower prostate cancer incidence compared to the rest of the world. It has been hypothesized that one of the potential contributing factors for this low incidence includes a higher intake of tocotrienols. Here we examine the potential of γ-tocotrienol (GT3) to reduce prostate cancer proliferation and focus on elucidating pathways by which GT3 could exert a growth-inhibitory effect on prostate cancer cells. We find that the γ and δ isoforms of tocotrienol are more effective at inhibiting the growth of prostate cancer cell lines (PC-3 and LNCaP) compared with the γ and δ forms of tocopherol. Knockout of PPAR-γ and GT3 treatment show inhibition of prostate cancer cell growth, through a partially PPAR-γ-dependent mechanism. GT3 treatment increases the levels of the 15-lipoxygenase-2 enzyme, which is responsible for the conversion of arachidonic acid to the PPAR-γ-activating ligand 15-S-hydroxyeicosatrienoic acid. In addition, the latent precursor and the mature forms of TGFβ2 are down-regulated after treatment with GT3, with concomitant disruptions in TGFβ receptor I, SMAD-2, p38, and NF-κB signaling., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Most anticancer drugs have their origin in traditional medicinal plants. We describe here a flavone, 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone (PMF), from the leaves of the Thai plant Gardenia obtusifolia, that has anti-inflammatory and anticancer potential. Because the nuclear factor-κB (NF-κB) pathway is linked to inflammation and tumorigenesis, we investigated the effect of PMF on this pathway. We found that PMF suppressed NF-κB activation induced by inflammatory agents, tumor promoters, and carcinogens. This suppression was not specific to the cell type. Although PMF did not directly modify the ability of NF-κB proteins to bind to DNA, it inhibited IκBα (inhibitory subunit of NF-κB) kinase, leading to suppression of phosphorylation and degradation of IκBα, and suppressed consequent p65 nuclear translocation, thus abrogating NF-κB-dependent reporter gene expression. Suppression of the NF-κB cell signaling pathway by the flavone led to the inhibition of expression of NF-κB-regulated gene products that mediate inflammation (cyclooxygenase-2), survival (XIAP, survivin, Bcl-xL, and cFLIP), proliferation (cyclin D1), invasion (matrix metalloproteinase-9), and angiogenesis (vascular endothelial growth factor). Suppression of antiapoptotic gene products by PMF correlated with the enhancement of apoptosis induced by tumor necrosis factor-α and the chemotherapeutic agents cisplatin, paclitaxel, and 5-flurouracil. Overall, our results indicate that PMF suppresses the activation of NF-κB and NF-κB-regulated gene expression, leading to the enhancement of apoptosis. This is the first report to demonstrate that this novel flavone has anti-inflammatory and anticancer effects by targeting the IKK complex.

TNF-related apoptosis-inducing ligand (TRAIL) shows promise as a cancer treatment, but acquired tumor resistance to TRAIL is a roadblock. Here we investigated whether nimbolide, a limonoid, could sensitize human colon cancer cells to TRAIL. As indicated by assays that measure esterase activity, sub-G(1) fractions, mitochondrial activity, and activation of caspases, nimbolide potentiated the effect of TRAIL. This limonoid also enhanced expression of death receptors (DRs) DR5 and DR4 in cancer cells. Gene silencing of the receptors reduced the effect of limonoid on TRAIL-induced apoptosis. Using pharmacological inhibitors, we found that activation of ERK and p38 MAPK was required for DR up-regulation by nimbolide. Gene silencing of ERK abolished the enhancement of TRAIL-induced apoptosis. Moreover, our studies indicate that the limonoid induced reactive oxygen species production, which was required for ERK activation, up-regulation of DRs, and sensitization to TRAIL; these effects were mimicked by H(2)O(2). In addition, nimbolide down-regulated cell survival proteins, including I-FLICE, cIAP-1, cIAP-2, Bcl-2, Bcl-xL, survivin, and X-linked inhibitor of apoptosis protein, and up-regulated the pro-apoptotic proteins p53 and Bax. Interestingly, p53 and Bax up-regulation by nimbolide was required for sensitization to TRAIL but not for DR up-regulation. Overall, our results indicate that nimbolide can sensitize colon cancer cells to TRAIL-induced apoptosis through three distinct mechanisms: reactive oxygen species- and ERK-mediated up-regulation of DR5 and DR4, down-regulation of cell survival proteins, and up-regulation of p53 and Bax.

Initially discovered in 1938 as a "fertility factor," vitamin E now refers to eight different isoforms that belong to two categories, four saturated analogues (α, β, γ, and δ) called tocopherols and four unsaturated analogues referred to as tocotrienols. While the tocopherols have been investigated extensively, little is known about the tocotrienols. Very limited studies suggest that both the molecular and therapeutic targets of the tocotrienols are distinct from those of the tocopherols. For instance, suppression of inflammatory transcription factor NF-κB, which is closely linked to tumorigenesis and inhibition of HMG-CoA reductase, mammalian DNA polymerases and certain protein tyrosine kinases, is unique to the tocotrienols. This review examines in detail the molecular targets of the tocotrienols and their roles in cancer, bone resorption, diabetes, and cardiovascular and neurological diseases at both preclinical and clinical levels. As disappointment with the therapeutic value of the tocopherols grows, the potential of these novel vitamin E analogues awaits further investigation., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The discovery of new uses for older, clinically approved drugs is one way to expedite drug development for cancer. Thiocolchicoside, a semisynthetic colchicoside from the plant Gloriosa superba, is a muscle relaxant and used to treat rheumatologic and orthopedic disorders because of its analgesic and anti-inflammatory mechanisms. Given that activation of the transcription factor NF-κB plays a major role in inflammation and tumorigenesis, we postulated that thiocolchicoside would inhibit NF-κB and exhibit anticancer effects through the modulation of NF-κB-regulated proteins. We show that thiocolchicoside inhibited proliferation of leukemia, myeloma, squamous cell carcinoma, breast, colon, and kidney cancer cells. Formation of tumor colonies was also suppressed by thiocolchicoside. The colchicoside induced apoptosis, as indicated by caspase-3 and poly(ADP-ribose) polymerase cleavage, and suppressed the expression of cell survival [e.g., Bcl-2, X-linked inhibitor of apoptosis (XIAP), MCL-1, bcl-xL, cIAP-1, cIAP-2, and cFLIP] proteins. Cell proliferation biomarkers such as c-MYC and phosphorylation of phosphoinositide 3-kinase and glycogen synthase kinase 3β were also blocked by thiocolchicoside. Because most cell survival and proliferation gene products are regulated by NF-κB, we studied the effect of thiocolchicoside on this transcription factor and found that thiocolchicoside inhibited NF-κB activation, degradation of inhibitory κBα (IκBα), IκBα ubiquitination, and phosphorylation, abolished the activation of IκBα kinase, and suppressed p65 nuclear translocation. This effect of thiocolchicoside on the NF-κB pathway led to inhibition of NF-κB reporter activity and cyclooxygenase-2 promoter activity. Our results indicate that thiocolchicoside exhibits anticancer activity through inhibition of NF-κB and NF-κB-regulated gene products, which provides novel insight into a half-century old drug., (©2010 AACR.)

Although γ-tocotrienol (T3), a vitamin E isolated primarily from palm and rice bran oil, has been linked with anticancer activities, the mechanism of this action is poorly understood. In this study, we investigated whether γ-T3 can modulate the STAT3 cell signaling pathway, closely linked to inflammation and tumorigenesis. We found that γ-T3 but not γ-tocopherol, the most common saturated form of vitamin E, inhibited constitutive activation of STAT3 in a dose- and time-dependent manner, and this inhibition was not cell type-specific. γ-T3 also inhibited STAT3 DNA binding. This correlated with inhibition of Src kinase and JAK1 and JAK2 kinases. Pervanadate reversed the γ-T3-induced down-regulation of STAT3 activation, suggesting the involvement of a protein-tyrosine phosphatase. When examined further, we found that γ-T3 induced the expression of the tyrosine phosphatase SHP-1, and gene silencing of the SHP-1 by small interfering RNA abolished the ability of γ-T3 to inhibit STAT3 activation, suggesting a vital role for SHP-1 in the action of γ-T3. Also γ-T3 down-modulated activation of STAT3 and induced SHP-1 in vivo. Eventually, γ-T3 down-regulated the expression of STAT3-regulated antiapoptotic (Bcl-2, Bcl-xL, and Mcl-1), proliferative (cyclin D1), and angiogenic (VEGF) gene products; and this correlated with suppression of proliferation, the accumulation of cells in sub-G(1) phase of the cell cycle, and induction of apoptosis. This vitamin also sensitized the tumor cells to the apoptotic effects of thalidomide and bortezomib. Overall, our results suggest that γ-T3 is a novel blocker of STAT3 activation pathway both in vitro and in vivo and thus may have potential in prevention and treatment of cancers.

Traditional medicine and diet has served mankind through the ages for prevention and treatment of most chronic diseases. Mounting evidence suggests that chronic inflammation mediates most chronic diseases, including cancer. More than other transcription factors, nuclear factor-kappaB (NF-κB) and STAT3 have emerged as major regulators of inflammation, cellular transformation, and tumor cell survival, proliferation, invasion, angiogenesis, and metastasis. Thus, agents that can inhibit NF-κB and STAT3 activation pathways have the potential to both prevent and treat cancer. In this review, we examine the potential of one group of compounds called triterpenes, derived from traditional medicine and diet for their ability to suppress inflammatory pathways linked to tumorigenesis. These triterpenes include avicins, betulinic acid, boswellic acid, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, and withanolide. This review thus supports the famous adage of Hippocrates, "Let food be thy medicine and medicine be thy food".

We sought to determine the molecular basis for the anticancer activities of 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone (DH-PMF), isolated from Gardenia obtusifolia traditionally used in Thailand for a variety of ailments. As little as 1 μM DH-PMF inhibited the proliferation of prostate, colon, kidney, lung, head and neck, pancreas, breast, leukemia, and myeloma cancer cell lines. DH-PMF also suppressed the colony-forming ability of tumor cells, with 50% inhibition occurring at a dose less than 10 nM. DH-PMF induced G(2)/M and subG(1) cell cycle arrest, increased the levels of p21(WAF1/CIP1) and p27(KIP1), and reduced the expression of cyclin D1, CDC2, and c-MYC. Furthermore, DH-PMF inhibited AKT and glycogen synthase kinase 3 beta (GSK3β) activation, reduced cell survival proteins, and induced apoptosis, as indicated by annexin V staining, TUNEL assay, and activation of caspase-8, -9 and -3. Overall, our results demonstrate that DH-PMF induces suppression of cell proliferation through modulation of AKT-GSK3β pathways and induction of cyclin-dependent kinase (CDK) inhibitors.

Crotepoxide (a substituted cyclohexane diepoxide), isolated from Kaempferia pulchra (peacock ginger), although linked to antitumor and anti-inflammatory activities, the mechanism by which it exhibits these activities, is not yet understood. Because nuclear factor kappaB (NF-kappaB) plays a critical role in these signaling pathways, we investigated the effects of crotepoxide on NF-kappaB-mediated cellular responses in human cancer cells. We found that crotepoxide potentiated tumor necrosis factor (TNF), and chemotherapeutic agents induced apoptosis and inhibited the expression of NF-kappaB-regulated gene products involved in anti-apoptosis (Bcl-2, Bcl-xL, IAP1,(2) MCl-1, survivin, and TRAF1), apoptosis (Bax, Bid), inflammation (COX-2), proliferation (cyclin D1 and c-myc), invasion (ICAM-1 and MMP-9), and angiogenesis (VEGF). We also found that crotepoxide inhibited both inducible and constitutive NF-kappaB activation. Crotepoxide inhibition of NF-kappaB was not inducer-specific; it inhibited NF-kappaB activation induced by TNF, phorbol 12-myristate 13-acetate, lipopolysaccharide, and cigarette smoke. Crotepoxide suppression of NF-kappaB was not cell type-specific because NF-kappaB activation was inhibited in myeloid, leukemia, and epithelial cells. Furthermore, we found that crotepoxide inhibited TAK1 activation, which led to suppression of IkappaBalpha kinase, abrogation of IkappaBalpha phosphorylation and degradation, nuclear translocation of p65, and suppression of NF-kappaB-dependent reporter gene expression. Overall, our results indicate that crotepoxide sensitizes tumor cells to cytokines and chemotherapeutic agents through inhibition of NF-kappaB and NF-kappaB-regulated gene products, and this may provide the molecular basis for crotepoxide ability to suppress inflammation and carcinogenesis.

Curcumin inhibits cell growth and induces apoptosis in a number of tumor cell lines and animal models. Human clinical trials indicated no dose-limiting toxicity when administered at doses up to 8 g per day. The purpose of this study was to address the antitumor effect of curcumin on cutaneous T-cell lymphoma (CTCL) cell lines and peripheral blood mononuclear cells (PBMCs) from patients with CTCL compared with healthy donors' controls. Curcumin at 5-20 microM for 24 and 48 hours induced apoptosis in a time- and dose-dependent manner in three CTCL cell lines (namely MJ, Hut78, and HH). Curcumin at 5-20 microM for 48 hours also caused more apoptosis in patients' PBMCs compared with healthy donors' PBMCs (P<0.05). Curcumin decreased protein and mRNA expression levels of signal transducer and activator of transcription (STAT)-3, bcl-2, and survivin in three cell lines and in patients' PBMCs. Curcumin inhibited STAT-3 and IkappaB-alpha phosphorylation, as well as suppressed DNA binding of nuclear factor (NF)-kappaB in these cells. Caspase-3 was activated and poly (ADP-Ribose) polymerase was cleaved after curcumin treatment. These data suggest that curcumin selectively induces apoptosis in association with the downregulation of STAT-3 and NF-kappaB signaling pathways in CTCL cells. Our findings provide a mechanistic rationale for the potential use of curcumin as a therapeutic agent for patients with CTCL.

Agents that are safe, affordable, and efficacious are urgently needed for the prevention of chronic diseases such as cancer. Sesamin, a lipid-soluble lignan, is one such agent that belongs to a class of phytoestrogens, isolated from sesame (Sesamum indicum), and has been linked with prevention of hyperlipidemia, hypertension, and carcinogenesis through an unknown mechanism. Because the transcription factor NF-kappaB has been associated with inflammation, carcinogenesis, tumor cell survival, proliferation, invasion, and angiogenesis of cancer, we postulated that sesamin might mediate its effect through the modulation of the NF-kappaB pathway. We found that sesamin inhibited the proliferation of a wide variety of tumor cells including leukemia, multiple myeloma, and cancers of the colon, prostate, breast, pancreas, and lung. Sesamin also potentiated tumor necrosis factor-alpha-induced apoptosis and this correlated with the suppression of gene products linked to cell survival (e.g., Bcl-2 and survivin), proliferation (e.g., cyclin D1), inflammation (e.g., cyclooxygenase-2), invasion (e.g., matrix metalloproteinase-9, intercellular adhesion molecule 1), and angiogenesis (e.g., vascular endothelial growth factor). Sesamin downregulated constitutive and inducible NF-kappaB activation induced by various inflammatory stimuli and carcinogens, and inhibited the degradation of IkappaBalpha, the inhibitor of NF-kappaB, through the suppression of phosphorylation of IkappaBalpha and inhibition of activation of IkappaBalpha protein kinase, thus resulting in the suppression of p65 phosphorylation and nuclear translocation, and NF-kappaB-mediated reporter gene transcription. The inhibition of IkappaBalpha protein kinase activation was found to be mediated through the inhibition of TAK1 kinase. Overall, our results showed that sesamin may have potential against cancer and other chronic diseases through the suppression of a pathway linked to the NF-kappaB signaling., ((c)2010 AACR.)

Diffuse large B-cell lymphoma (DLBCL) is an aggressive subtype of B-cell non-Hodgkin lymphoma (NHL) and accounts for 30%to 40%of NHL. Molecules targeting nuclear factor-kappaB (NF-kappaB) are expected to be of therapeutic value in those tumors where NF-kappaB seems to play a unique survival role such as activated B-cell (ABC)-subtype DLBCL. We previously generated a rGel/BLyS fusion toxin for receptor-mediated delivery of the rGel toxin specifically to malignant B cells. In this study, we examined this fusion toxin for its ability to suppress DLBCL growth in vitro and in vivo. rGel/BLyS was specifically cytotoxic to DLBCL lines expressing all three BLyS receptors and constitutively active NF-kappaB. Treatment with rGel/BLyS induced down-regulation of the phosphorylation of inhibitory subunit of NF-kappaB (IkappaB-alpha), inhibition of NF-kappaB DNA-binding activity, and accumulation of IkappaB-alpha. In agreement with these results, we additionally found that rGel/BLyS downregulated levels of several NF-kappaB targets including Bcl-xL, Mcl-1, survivin, and x-chromosome linked inhibitor-of-apoptosis. Treatment also induced up-regulation of Bax and apoptosis through caspase-3 activation and poly ADP-ribose polymerase cleavage. Importantly, rGel/BLyS significantly inhibited tumor growth (P < .05) in a DLBCL xenograft model. Thus, our results indicate that rGel/BLyS is an excellent candidate for the treatment of aggressive NHLs that are both dependent on NF-kappaB and are resistant to conventional chemotherapeutic regimens.

Because of the poor prognosis and the development of resistance against chemotherapeutic drugs, the current treatment for advanced metastatic colorectal cancer (CRC) is ineffective. Whether curcumin (a component of turmeric) can potentiate the effect of capecitabine against growth and metastasis of CRC was investigated. The effect of curcumin on proliferation of CRC cell lines was examined by mitochondrial dye-uptake assay, apoptosis by esterase staining, nuclear factor-kappaB (NF-kappaB) by electrophoretic mobility shift assay and gene expression by Western blot analysis. The effect of curcumin on the growth and metastasis of CRC was also examined in orthotopically implanted tumors in nude mice. In vitro, curcumin inhibited the proliferation of human CRC cell lines, potentiated capecitabine-induced apoptosis, inhibited NF-kappaB activation and suppressed NF-kappaB-regulated gene products. In nude mice, the combination of curcumin and capecitabine was found to be more effective than either agent alone in reducing tumor volume (p = 0.001 vs. control; p = 0.031 vs. capecitabine alone), Ki-67 proliferation index (p = 0.001 vs. control) and microvessel density marker CD31. The combination treatment was also highly effective in suppressing ascites and distant metastasis to the liver, intestines, lungs, rectum and spleen. This effect was accompanied by suppressed expression of activated NF-kappaB and NF-kappaB-regulated gene products (cyclin D1,c-myc, bcl-2, bcl-xL, cIAP-1, COX-2, ICAM-1, MMP-9, CXCR4 and VEGF). Overall, our results suggest that curcumin sensitizes CRC to the antitumor and antimetastatic effects of capecitabine by suppressing NF-kappaB cell signaling pathway., ((c) 2009 UICC.)

Recent studies have demonstrated that K-ras mutations in lung epithelial cells elicit inflammation that promotes carcinogenesis in mice (intrinsic inflammation). The finding that patients with chronic obstructive pulmonary disease (COPD), an inflammatory disease of the lung, have an increased risk of lung cancer after controlling for smoking suggests a further link between lung cancer and extrinsic inflammation. Besides exposure to cigarette smoke, it is thought that airway inflammation in COPD is caused by bacterial colonization, particularly with non-typeable Hemophilus influenzae (NTHi). Previously, we have shown that NTHi-induced COPD-like airway inflammation promotes lung cancer in an airway conditional K-ras-induced mouse model. To further test the role of inflammation in cancer promotion, we administered the natural anti-inflammatory agent, curcumin, 1% in diet before and during weekly NTHi exposure. This significantly reduced the number of visible lung tumors in the absence of NTHi exposure by 85% and in the presence of NTHi exposures by 53%. Mechanistically, curcumin markedly suppressed NTHi-induced increased levels of the neutrophil chemoattractant keratinocyte-derived chemokine by 80% and neutrophils by 87% in bronchoalveolar lavage fluid. In vitro studies of murine K-ras-induced lung adenocarcinoma cell lines (LKR-10 and LKR-13) indicated direct anti-tumoral effects of curcumin by reducing cell viability, colony formation and inducing apoptosis. We conclude that curcumin suppresses the progression of K-ras-induced lung cancer in mice by inhibiting intrinsic and extrinsic inflammation and by direct anti-tumoral effects. These findings suggest that curcumin could be used to protract the premalignant phase and inhibit lung cancer progression in high-risk COPD patients.

Cancer is a hyperproliferative disorder that is usually treated by chemotherapeutic agents that are toxic not only to tumor cells but also to normal cells, so these agents produce major side effects. In addition, these agents are highly expensive and thus not affordable for most. Moreover, such agents cannot be used for cancer prevention. Traditional medicines are generally free of the deleterious side effects and usually inexpensive. Curcumin, a component of turmeric (Curcuma longa), is one such agent that is safe, affordable, and efficacious. How curcumin kills tumor cells is the focus of this review. We show that curcumin modulates growth of tumor cells through regulation of multiple cell signaling pathways including cell proliferation pathway (cyclin D1, c-myc), cell survival pathway (Bcl-2, Bcl-xL, cFLIP, XIAP, c-IAP1), caspase activation pathway (caspase-8, 3, 9), tumor suppressor pathway (p53, p21) death receptor pathway (DR4, DR5), mitochondrial pathways, and protein kinase pathway (JNK, Akt, and AMPK). How curcumin selectively kills tumor cells, and not normal cells, is also described in detail.

Because most cancers are caused by dysregulation of as many as 500 different genes, agents that target multiple gene products are needed for prevention and treatment of cancer. Curcumin, a yellow coloring agent in turmeric, has been shown to interact with a wide variety of proteins and modify their expression and activity. These include inflammatory cytokines and enzymes, transcription factors, and gene products linked with cell survival, proliferation, invasion, and angiogenesis. Curcumin has been found to inhibit the proliferation of various tumor cells in culture, prevents carcinogen-induced cancers in rodents, and inhibits the growth of human tumors in xenotransplant or orthotransplant animal models either alone or in combination with chemotherapeutic agents or radiation. Several phase I and phase II clinical trials indicate that curcumin is quite safe and may exhibit therapeutic efficacy. These aspects of curcumin are discussed further in detail in this review.

Compounds isolated from members of the Zingiberaceae family are traditionally used as a medicine against inflammatory diseases, but little is known about the mechanism. Here, we report the isolation and structural identification of coronarin D [E-labda-8(17),12-diene-15-ol], a labdane-type diterpene, from Hedychium coronarium and delineate its mechanism of action. Because the transcription factor nuclear factor-kappaB (NF-kappaB) is a key mediator of inflammation, apoptosis, invasion, and osteoclastogenesis, we investigated the effect of coronarin D on NF-kappaB activation pathway, NF-kappaB-regulated gene products, and NF-kappaB-regulated cellular responses. The coronarin D inhibited NF-kappaB activation induced by different inflammatory stimuli and carcinogens. This labdane also suppressed constitutive NF-kappaB activity in different cell lines and inhibited IkappaBalpha kinase activation, thus leading to the suppression of IkappaBalpha phosphorylation, degradation, p65 nuclear translocation, and reporter gene transcription. Coronarin D also inhibited the NF-kappaB-regulated gene products involved in cell survival (inhibitor of apoptosis protein 1, Bcl-2, survivin, and tumor necrosis factor receptor-associated factor-2), proliferation (c-myc, cyclin D1, and cyclooxygenase-2), invasion (matrix metalloproteinase-9), and angiogenesis (vascular endothelial growth factor). Suppression of these gene products by the diterpene enhanced apoptosis induced by TNF and chemotherapeutic agents, suppressed TNF-induced cellular invasion, and abrogated receptor activator of NF-kappaB ligand-induced osteoclastogenesis. Coronarin D was found to be more potent than its analogue coronarin D acid. Overall, our results show that coronarin D inhibited NF-kappaB activation pathway, which leads to inhibition of inflammation, invasion, and osteoclastogenesis, as well as potentiation of apoptosis.

Although traditional medicines have been used for thousands of years, for most such medicines neither the active component nor their molecular targets have been very well identified. Curcumin, a yellow component of turmeric or curry powder, however, is an exception. Although inhibitors of cyclooxygenase-2, HER2, tumor necrosis factor, EGFR, Bcr-abl, proteosome, and vascular endothelial cell growth factor have been approved for human use by the United States Food and Drug Administration (FDA), curcumin as a single agent can down-regulate all these targets. Curcumin can also activate apoptosis, down-regulate cell survival gene products, and up-regulate p53, p21, and p27. Although curcumin is poorly absorbed after ingestion, multiple studies have suggested that even low levels of physiologically achievable concentrations of curcumin may be sufficient for its chemopreventive and chemotherapeutic activity. Thus, curcumin regulates multiple targets (multitargeted therapy), which is needed for treatment of most diseases, and it is inexpensive and has been found to be safe in human clinical trials. The present article reviews the key molecular mechanisms of curcumin action and compares this to some of the single-targeted therapies currently available for human cancer.

Cancer is primarily a disease of old age, and that life style plays a major role in the development of most cancers is now well recognized. While plant-based formulations have been used to treat cancer for centuries, current treatments usually involve poisonous mustard gas, chemotherapy, radiation, and targeted therapies. While traditional plant-derived medicines are safe, what are the active principles in them and how do they mediate their effects against cancer is perhaps best illustrated by curcumin, a derivative of turmeric used for centuries to treat a wide variety of inflammatory conditions. Curcumin is a diferuloylmethane derived from the Indian spice, turmeric (popularly called "curry powder") that has been shown to interfere with multiple cell signaling pathways, including cell cycle (cyclin D1 and cyclin E), apoptosis (activation of caspases and down-regulation of antiapoptotic gene products), proliferation (HER-2, EGFR, and AP-1), survival (PI3K/AKT pathway), invasion (MMP-9 and adhesion molecules), angiogenesis (VEGF), metastasis (CXCR-4) and inflammation (NF-kappaB, TNF, IL-6, IL-1, COX-2, and 5-LOX). The activity of curcumin reported against leukemia and lymphoma, gastrointestinal cancers, genitourinary cancers, breast cancer, ovarian cancer, head and neck squamous cell carcinoma, lung cancer, melanoma, neurological cancers, and sarcoma reflects its ability to affect multiple targets. Thus an "old-age" disease such as cancer requires an "age-old" treatment.

Purpose: Pancreatic cancer is almost always lethal, and the only U.S. Food and Drug Administration-approved therapies for it, gemcitabine and erlotinib, produce objective responses in <10% of patients. We evaluated the clinical biological effects of curcumin (diferuloylmethane), a plant-derived dietary ingredient with potent nuclear factor-kappaB (NF-kappaB) and tumor inhibitory properties, against advanced pancreatic cancer., Experimental Design: Patients received 8 g curcumin by mouth daily until disease progression, with restaging every 2 months. Serum cytokine levels for interleukin (IL)-6, IL-8, IL-10, and IL-1 receptor antagonists and peripheral blood mononuclear cell expression of NF-kappaB and cyclooxygenase-2 were monitored., Results: Twenty-five patients were enrolled, with 21 evaluable for response. Circulating curcumin was detectable as drug in glucuronide and sulfate conjugate forms, albeit at low steady-state levels, suggesting poor oral bioavailability. Two patients showed clinical biological activity. One had ongoing stable disease for >18 months; interestingly, one additional patient had a brief, but marked, tumor regression (73%) accompanied by significant increases (4- to 35-fold) in serum cytokine levels (IL-6, IL-8, IL-10, and IL-1 receptor antagonists). No toxicities were observed. Curcumin down-regulated expression of NF-kappaB, cyclooxygenase-2, and phosphorylated signal transducer and activator of transcription 3 in peripheral blood mononuclear cells from patients (most of whom had baseline levels considerably higher than those found in healthy volunteers). Whereas there was considerable interpatient variation in plasma curcumin levels, drug levels peaked at 22 to 41 ng/mL and remained relatively constant over the first 4 weeks., Conclusions: Oral curcumin is well tolerated and, despite its limited absorption, has biological activity in some patients with pancreatic cancer.

Thymoquinone (TQ), derived from the medicinal plant Nigella sativa, exhibits antiinflammatory and anticancer activities through mechanism(s) that is not fully understood. Because numerous effects modulated by TQ can be linked to interference with the nuclear factor-kappaB (NF-kappa B) signaling, we investigated in detail the effect of this quinone on NF-kappa B pathway. As examined by DNA binding, we found that TQ suppressed tumor necrosis factor-induced NF-kappa B activation in a dose- and time-dependent manner and inhibited NF-kappaB activation induced by various carcinogens and inflammatory stimuli. The suppression of NF-kappaB activation correlated with sequential inhibition of the activation of I kappa B alpha kinase, I kappa B alpha phosphorylation, I kappa B alpha degradation, p65 phosphorylation, p65 nuclear translocation, and the NF-kappa B-dependent reporter gene expression. TQ specifically suppressed the direct binding of nuclear p65 and recombinant p65 to the DNA, and this binding was reversed by DTT. However, TQ did not inhibit p65 binding to DNA when cells were transfected with the p65 plasmid containing cysteine residue 38 mutated to serine. TQ also down-regulated the expression of NF-kappa B-regulated antiapoptotic (IAP1, IAP2, XIAP Bcl-2, Bcl-xL, and survivin), proliferative (cyclin D1, cyclooxygenase-2, and c-Myc), and angiogenic (matrix metalloproteinase-9 and vascular endothelial growth factor) gene products. This led to potentiation of apoptosis induced by tumor necrosis factor and chemotherapeutic agents. Overall, our results indicate that the anticancer and antiinflammatory activities previously assigned to TQ may be mediated in part through the suppression of the NF-kappa B activation pathway, as shown here, and thus may have potential in treatment of myeloid leukemia and other cancers.

Although turmeric (Curcuma longa; an Indian spice) has been described in Ayurveda, as a treatment for inflammatory diseases and is referred by different names in different cultures, the active principle called curcumin or diferuloylmethane, a yellow pigment present in turmeric (curry powder) has been shown to exhibit numerous activities. Extensive research over the last half century has revealed several important functions of curcumin. It binds to a variety of proteins and inhibits the activity of various kinases. By modulating the activation of various transcription factors, curcumin regulates the expression of inflammatory enzymes, cytokines, adhesion molecules, and cell survival proteins. Curcumin also downregulates cyclin D1, cyclin E and MDM2; and upregulates p21, p27, and p53. Various preclinical cell culture and animal studies suggest that curcumin has potential as an antiproliferative, anti-invasive, and antiangiogenic agent; as a mediator of chemoresistance and radioresistance; as a chemopreventive agent; and as a therapeutic agent in wound healing, diabetes, Alzheimer disease, Parkinson disease, cardiovascular disease, pulmonary disease, and arthritis. Pilot phase I clinical trials have shown curcumin to be safe even when consumed at a daily dose of 12g for 3 months. Other clinical trials suggest a potential therapeutic role for curcumin in diseases such as familial adenomatous polyposis, inflammatory bowel disease, ulcerative colitis, colon cancer, pancreatic cancer, hypercholesteremia, atherosclerosis, pancreatitis, psoriasis, chronic anterior uveitis and arthritis. Thus, curcumin, a spice once relegated to the kitchen shelf, has moved into the clinic and may prove to be "Curecumin".

We recently found that simvastatin can modulate the nuclear factor-kappaB (NF-kappaB) activation pathway, but whether other statins have similar effects to those of simvastatin is unknown. Therefore, we evaluated the effect six different statins on TNF-induced NF-kappaB activation in human myeloid leukemia cells. We then determined whether the combination of statins and standard chemotherapeutic agents could overcome chemoresistance and augment apoptosis. Of the six statins evaluated, only the natural statins (simvastatin, mevastatin, lovastatin, and pravastatin), not the synthetic statins (fluvastatin and atorvastatin), inhibited TNF-induced NF-kappaB activation. Simvastatin suppressed the NF-kappaB activation and potentiated the apoptosis induced by doxorubicin, paclitaxel, and 5-fluorouracil. These results suggest that different statins behave differently from one another and that they may be useful in overcoming chemoresistance.

Autophagy is a response of cancer cells to various anticancer therapies. It is designated as programmed cell death type II and characterized by the formation of autophagic vacuoles in the cytoplasm. The Akt/mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase (p70S6K) and the extracellular signal-regulated kinases 1/2 (ERK1/2) pathways are two major pathways that regulate autophagy induced by nutrient starvation. These pathways are also frequently associated with oncogenesis in a variety of cancer cell types, including malignant gliomas. However, few studies have examined both of these signal pathways in the context of anticancer therapy-induced autophagy in cancer cells, and the effect of autophagy on cell death remains unclear. Here, we examined the anticancer efficacy and mechanisms of curcumin, a natural compound with low toxicity in normal cells, in U87-MG and U373-MG malignant glioma cells. Curcumin induced G(2)/M arrest and nonapoptotic autophagic cell death in both cell types. It inhibited the Akt/mTOR/p70S6K pathway and activated the ERK1/2 pathway, resulting in induction of autophagy. It is interesting that activation of the Akt pathway inhibited curcumin-induced autophagy and cytotoxicity, whereas inhibition of the ERK1/2 pathway inhibited curcumin-induced autophagy and induced apoptosis, thus resulting in enhanced cytotoxicity. These results imply that the effect of autophagy on cell death may be pathway-specific. In the subcutaneous xenograft model of U87-MG cells, curcumin inhibited tumor growth significantly (P < 0.05) and induced autophagy. These results suggest that curcumin has high anticancer efficacy in vitro and in vivo by inducing autophagy and warrant further investigation toward possible clinical application in patients with malignant glioma.

Guggulsterone is a plant polyphenol traditionally used to treat obesity, diabetes, hyperlipidemia, atherosclerosis, and osteoarthritis, possibly through an anti-inflammatory mechanism. Whether this steroid has any role in cancer is not known. In this study, we found that guggulsterone inhibits the proliferation of wide variety of human tumor cell types including leukemia, head and neck carcinoma, multiple myeloma, lung carcinoma, melanoma, breast carcinoma, and ovarian carcinoma. Guggulsterone also inhibited the proliferation of drug-resistant cancer cells (e.g., gleevac-resistant leukemia, dexamethasone-resistant multiple myeloma, and doxorubicin-resistant breast cancer cells). Guggulsterone suppressed the proliferation of cells through inhibition of DNA synthesis, producing cell cycle arrest in S-phase, and this arrest correlated with a decrease in the levels of cyclin D1 and cdc2 and a concomitant increase in the levels of cyclin-dependent kinase inhibitor p21 and p27. Guggulsterone-induced apoptosis as indicated by increase in the number of Annexin V- and TUNEL-positive cells, through the downregulation of anti-apoptototic products. The apoptosis induced by guggulsterone was also indicated by the activation of caspase-8, bid cleavage, cytochrome c release, caspase-9 activation, caspase-3 activation, and PARP cleavage. The apoptotic effects of guggulsterone were preceded by activation of JNK and downregulation of Akt activity. JNK was needed for guggulsterone-induced apoptosis, inasmuch as inhibition of JNK by pharmacological inhibitors or by genetic deletion of MKK4 (activator of JNK) abolished the activity. Overall, our results indicate that guggulsterone can inhibit cell proliferation and induce apoptosis through the activation of JNK, suppression of Akt, and downregulation of antiapoptotic protein expression.

Purpose: Curcumin, a component of turmeric, has been shown to suppress inflammation and angiogenesis largely by inhibiting the transcription factor nuclear factor-kappaB (NF-kappaB). This study evaluates the effects of curcumin on ovarian cancer growth using an orthotopic murine model of ovarian cancer., Experimental Design: In vitro and in vivo experiments of curcumin with and without docetaxel were done using human ovarian cancer cell lines SKOV3ip1, HeyA8, and HeyA8-MDR in athymic mice. NF-kappaB modulation was ascertained using electrophoretic mobility shift assay. Evaluation of angiogenic cytokines, cellular proliferation (proliferating cell nuclear antigen), angiogenesis (CD31), and apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) was done using immunohistochemical analyses., Results: Curcumin inhibited inducible NF-kappaB activation and suppressed proliferation in vitro. In vivo dose-finding experiments revealed that 500 mg/kg orally was the optimal dose needed to suppress NF-kappaB and signal transducers and activators of transcription 3 activation and decrease angiogenic cytokine expression. In the SKOV3ip1 and HeyA8 in vivo models, curcumin alone resulted in 49% (P = 0.08) and 55% (P = 0.01) reductions in mean tumor growth compared with controls, whereas when combined with docetaxel elicited 96% (P < 0.001) and 77% reductions in mean tumor growth compared with controls. In mice with multidrug-resistant HeyA8-MDR tumors, treatment with curcumin alone and combined with docetaxel resulted in significant 47% and 58% reductions in tumor growth, respectively (P = 0.05). In SKOV3ip1 and HeyA8 tumors, curcumin alone and with docetaxel decreased both proliferation (P < 0.001) and microvessel density (P < 0.001) and increased tumor cell apoptosis (P < 0.05)., Conclusions: Based on significant efficacy in preclinical models, curcumin-based therapies may be attractive in patients with ovarian carcinoma.

Smokeless tobacco (ST) consumption is a major cause of oral cancer in South East Asia including India. Recently, we showed that exposure to smokeless tobacco extract (STE) (khaini) results in increased expression and activation of nuclear factor-kappaB (NF-kappaB) and its downstream target cyclooxygenase-2 (COX-2) in human oral cell systems in vitro. The present study was designed to test the hypothesis that curcumin may inhibit the activation of NF-kappaB in ST exposed oral premalignant and cancer cells. Exposure of oral premalignant and cancer cells to curcumin resulted in significant decrease in cell viability and induced apoptosis. STE-induced nuclear translocation and DNA-binding activity of NF-kappaB were inhibited in curcumin pretreated oral premalignant and cancer cells in vitro. Curcumin treatment led to decreased expression of NF-kappaB and COX-2. The tobacco specific nitrosamine, 4-(methylnitrosamino-)-1-(3-pyridyl)-1-butanone (NNK), is one of the carcinogenic components of STE (khaini). We demonstrate that curcumin pretreatment abrogated NNK-induced activation of NF-kappaB and COX-2 expression, suggesting that NNK is one of the factors in STE (khaini) modulated by curcumin. In conclusion, our findings demonstrate for the first time that curcumin downregulates STE (khaini) or NNK-induced NF-kappaB and COX-2 in oral premalignant and cancer cells in vitro.

Silymarin consists of a family of flavonoids (silybin, isosilybin, silychristin, silydianin and taxifoline) commonly found in the dried fruit of the milk thistle plant Silybum marianum. Although silymarin's role as an antioxidant and hepatoprotective agent is well known, its role as an anticancer agent has begun to emerge. Extensive research within the last decade has shown that silymarin can suppress the proliferation of a variety of tumor cells (e.g., prostate, breast, ovary, colon, lung, bladder); this is accomplished through cell cycle arrest at the G1/S-phase, induction of cyclin-dependent kinase inhibitors (such as p15, p21 and p27), down-regulation of anti-apoptotic gene products (e.g., Bcl-2 and Bcl-xL), inhibition of cell-survival kinases (AKT, PKC and MAPK) and inhibition of inflammatory transcription factors (e.g., NF-kappaB). Silymarin can also down-regulate gene products involved in the proliferation of tumor cells (cyclin D1, EGFR, COX-2, TGF-beta, IGF-IR), invasion (MMP-9), angiogenesis (VEGF) and metastasis (adhesion molecules). The antiinflammatory effects of silymarin are mediated through suppression of NF-kappaB-regulated gene products, including COX-2, LOX, inducible iNOS, TNF and IL-1. Numerous studies have indicated that silymarin is a chemopreventive agent in vivo against a variety of carcinogens/tumor promoters, including UV light, 7,12-dimethylbenz(a)anthracene (DMBA), phorbol 12-myristate 13-acetate (PMA) and others. Silymarin has also been shown to sensitize tumors to chemotherapeutic agents through down-regulation of the MDR protein and other mechanisms. It binds to both estrogen and androgen receptors, and down-regulates PSA. In addition to its chemopreventive effects, silymarin exhibits antitumor activity against human tumors (e.g., prostate and ovary) in rodents. Various clinical trials have indicated that silymarin is bioavailable and pharmacologically safe. Studies are now in progress to demonstrate the clinical efficacy of silymarin against various cancers.

Numerous reports suggest that interleukin-6 (IL-6) promotes survival and proliferation of tumor cells through the phosphorylation of a cell-signaling protein, signal-transducer-and-activator-of-transcription-3 (STAT3). Constitutive activation of STAT3 in head and neck squamous cell carcinoma (HNSCC) and its role in proliferation of this tumor has been demonstrated. Thus, agents that can suppress STAT3 activation have potential for the treatment of HNSCC. In the present report, we demonstrate that most HNSCC cell lines had constitutively active STAT3 and that curcumin (diferuloylmethane), a pharmacologically safe agent in humans, inhibited STAT3 phosphorylation in a dose- and time-dependent manner. Nuclear translocation of STAT3 was also inhibited by curcumin. The inhibition of STAT3 activation by curcumin was reversible, although even 24 hr after curcumin removal, only partial reversal occurred. Besides inhibiting constitutive expression, curcumin also abrogated the IL-6-induced activation of STAT3 in HNSCC cells. When compared with AG490, a well-characterized JAK2 inhibitor, curcumin was more rapid (30 min vs. 4 hr) and more potent (25 microM vs. 100 microM) inhibitor of STAT3 phosphorylation. Curcumin was also a more potent inhibitor of HNSCC cell proliferation than AG490. Overall, our results demonstrated that curcumin is a potent inhibitor of constitutive and IL-6-induced STAT3 phosphorylation. This mechanism may be at least partially responsible for curcumin's ability to suppress proliferation of HNSCC cells.

Because of its ability to suppress tumor cell proliferation, angiogenesis, and inflammation, the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) is currently in clinical trials. How SAHA mediates its effects is poorly understood. We found that in several human cancer cell lines, SAHA potentiated the apoptosis induced by tumor necrosis factor (TNF) and chemotherapeutic agents and inhibited TNF-induced invasion and receptor activator of NF-kappaB ligand-induced osteoclastogenesis, all of which are known to require NF-kappaB activation. These observations corresponded with the down-regulation of the expression of anti-apoptotic (IAP1, IAP2, X chromosome-linked IAP, Bcl-2, Bcl-x(L), TRAF1, FLIP, and survivin), proliferative (cyclin D1, cyclooxygenase 2, and c-Myc), and angiogenic (ICAM-1, matrix metalloproteinase-9, and vascular endothelial growth factor) gene products. Because several of these genes are regulated by NF-kappaB, we postulated that SAHA mediates its effects by modulating NF-kappaB and found that SAHA suppressed NF-kappaB activation induced by TNF, IL-1beta, okadaic acid, doxorubicin, lipopolysaccharide, H(2)O(2), phorbol myristate acetate, and cigarette smoke; the suppression was not cell type-specific because both inducible and constitutive NF-kappaB activation was inhibited. We also found that SAHA had no effect on direct binding of NF-kappaB to the DNA but inhibited sequentially the TNF-induced activation of IkappaBalpha kinase, IkappaBalpha phosphorylation, IkappaBalpha ubiquitination, IkappaBalpha degradation, p65 phosphorylation, and p65 nuclear translocation. Furthermore, SAHA inhibited the NF-kappaB-dependent reporter gene expression activated by TNF, TNFR1, TRADD, TRAF2, NF-kappaB-inducing kinase, IkappaBalpha kinase, and the p65 subunit of NF-kappaB. Overall, our results indicated that NF-kappaB and NF-kappaB-regulated gene expression inhibited by SAHA can enhance apoptosis and inhibit invasion and osteoclastogenesis.

Acetyl-11-keto-beta-boswellic acid (AKBA), a component of an Ayurvedic therapeutic plant Boswellia serrata, is a pentacyclic terpenoid active against a large number of inflammatory diseases, including cancer, arthritis, chronic colitis, ulcerative colitis, Crohn's disease, and bronchial asthma, but the mechanism is poorly understood. We found that AKBA potentiated the apoptosis induced by TNF and chemotherapeutic agents, suppressed TNF-induced invasion, and inhibited receptor activator of NF-kappaB ligand-induced osteoclastogenesis, all of which are known to require NF-kappaB activation. These observations corresponded with the down-regulation of the expression of NF-kappaB-regulated antiapoptotic, proliferative, and angiogenic gene products. As examined by DNA binding, AKBA suppressed both inducible and constitutive NF-kappaB activation in tumor cells. It also abrogated NF-kappaB activation induced by TNF, IL-1beta, okadaic acid, doxorubicin, LPS, H2O2, PMA, and cigarette smoke. AKBA did not directly affect the binding of NF-kappaB to the DNA but inhibited sequentially the TNF-induced activation of IkappaBalpha kinase (IKK), IkappaBalpha phosphorylation, IkappaBalpha ubiquitination, IkappaBalpha degradation, p65 phosphorylation, and p65 nuclear translocation. AKBA also did not directly modulate IKK activity but suppressed the activation of IKK through inhibition of Akt. Furthermore, AKBA inhibited the NF-kappaB-dependent reporter gene expression activated by TNFR type 1, TNFR-associated death domain protein, TNFR-associated factor 2, NF-kappaB-inducing kinase, and IKK, but not that activated by the p65 subunit of NF-kappaB. Overall, our results indicated that AKBA enhances apoptosis induced by cytokines and chemotherapeutic agents, inhibits invasion, and suppresses osteoclastogenesis through inhibition of NF-kappaB-regulated gene expression.