Capsazepine, a TRPV1 antagonist, sensitizes colorectal cancer cells to apoptosis by TRAIL through ROS-JNK-CHOP-mediated upregulation of death receptors.

A major problem in clinical trials of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as cancer therapy is the development of resistance to TRAIL. Therefore, agents that can overcome TRAIL resistance have great therapeutic potential. In this study, we evaluated capsazepine, a TRPV1 antagonist, for its ability to sensitize human colon cancer cells to TRAIL-induced apoptosis. Capsazepine potentiated the effect of TRAIL, as shown by its effect on intracellular esterase activity; activation of caspase-8,-9, and -3; and colony-formation assay. Capsazepine induced death receptors (DRs) DR5 and DR4, but not decoy receptors, at the transcriptional level and in a non-cell-type-specific manner. DR induction was dependent on CCAAT/enhancer-binding protein homologous protein (CHOP), as shown by (a) the induction of CHOP by capsazepine and (b) the abolition of DR- and potentiation of TRAIL-induced apoptosis by CHOP gene silencing. CHOP induction was also reactive oxygen species (ROS)-dependent, as shown by capsazepine's ability to induce ROS and by the quenching of ROS by N-acetylcysteine or glutathione, which prevented induction of CHOP and DR5 and consequent sensitization to TRAIL. Capsazepine's effects appeared to be mediated via JNK, as shown by capsazepine's ability to induce JNK and by the suppression of both CHOP and DR5 activation by inhibition of JNK. Furthermore, ROS sequestration abrogated the activation of JNK. Finally, capsazepine downregulated the expression of various antiapoptotic proteins (e.g., cFLIP and survivin) and increased the expression of proapoptotic proteins (e.g., Bax and p53). Together, our results indicate that capsazepine potentiates the apoptotic effects of TRAIL through downregulation of cell survival proteins and upregulation of death receptors via the ROS-JNK-CHOP-mediated pathway.

Zyflamend suppresses growth and sensitizes human pancreatic tumors to gemcitabine in an orthotopic mouse model through modulation of multiple targets.

Agents that can potentiate the efficacy of standard chemotherapy against pancreatic cancer are of great interest. Because of their low cost and safety, patients commonly use a variety of dietary supplements, although evidence of their efficacy is often lacking. One such commonly used food supplement is Zyflamend, a polyherbal preparation with potent anti-inflammatory activities and preclinical efficacy against prostate and oral cancer. Whether Zyflamend has any efficacy against human pancreatic cancer alone or in combination with gemcitibine, a commonly used agent, was examined in cell cultures and in an orthotopic mouse model. In vitro, Zyflamend inhibited the proliferation of pancreatic cancer cell lines regardless of p53 status and also enhanced gemcitabine-induced apoptosis. This finding correlated with inhibition of NF-κB activation by Zyflamend and suppression of cyclin D1, c-myc, COX-2, Bcl-2, IAP, survivin, VEGF, ICAM-1 and CXCR4. In nude mice, oral administration of Zyflamend alone significantly inhibited the growth of orthotopically transplanted human pancreatic tumors, and when combined with gemcitabine, further enhanced the antitumor effects. Immunohistochemical and Western blot analyses of tumor tissue showed that the suppression of pancreatic cancer growth correlated with inhibition of proliferation index marker (Ki-67), COX-2, MMP-9, NF-κB and VEGF. Overall, these results suggest that the concentrated multiherb product Zyflamend alone can inhibit the growth of human pancreatic tumors and, in addition, can sensitize pancreatic cancers to gemcitabine through the suppression of multiple targets linked to tumorigenesis.

Differential toxicity profile of ricin isoforms correlates with their glycosylation levels.

Ricin is one of the most potent and deadly plant toxins from the seeds of Ricinus communis. In view of its high toxicity, ricin is being used as an immunotoxin in cancer therapy. Ricin also has several isoforms with differential glycosylation depending on the seed variety. Our study shows three isoforms designated 1, 2 and 3, which differed in their surface charge, resulting in a different behavior on cation exchange chromatography, two dimensional (pI 5.5-8.7) and native PAGE. The molecular masses of isoform-1, 2 and 3 were measured as 63.55 kDa, 64.03 kDa and 62.8 kDa, respectively, by MALDI-TOF/MS. In vitro studies with monkey kidney (Vero) cells showed a time dependent increase in cytotoxicity of the isoforms evaluated by extracellular lactate dehydrogenase activity and mitochondrial dehydrogenase assay. These isoforms also induce oxidative stress and DNA damage. Among the isoforms, isoform-3 was quick to generate reactive oxygen species (ROS), (in 90 min) and exhibited maximum cytotoxicity. Morphological changes, catalase activity and DNA fragmentation were significantly higher with isoform-3 treatment compared to others. The glycosylation studies by MALDI-TOF/MS showed that isoform-3 is highly glycosylated with high sugar levels containing more of hybrid/complex type glycopeptides with mannose as hexose units. These experimental evidences clearly suggest that isoform-3 is superior in its early ROS generation, potency to induce oxidative stress and cytotoxicity, that could be due to it's higher glycosylation levels which make isoform-3 as an ideal candidate for immunotoxin studies.

Alteration of blood brain barrier permeability by T-2 toxin: Role of MMP-9 and inflammatory cytokines.

T-2 toxin is a cytotoxic fungal secondary metabolite produced by different species of Fusarium such as F. sporotichioides, F. poae, F. equiseti, F. acuminatum etc. This class of mycotoxins causes a number of pathologies including nervous disorders, cardiovascular alterations, immunodepression and hemostatic derangements. In the present study, mechanism of T-2 toxin induced alteration of blood-brain barrier (BBB) permeability was assessed in terms of oxidative stress, gene expression of MMP-9, MMP-2 and their inhibitors TIMP-1 and TIMP-2, activation of inflammatory cytokines in both brain and peripheral tissue spleen. Gel zymography was used to show the activity of MMP-9 and MMP-2. The percutaneous exposure of 1 LD50 T2 toxin caused a reversible alteration in BBB permeability as observed by extravasation of Evans blue dye. Maximum dye level was observed on day 3 and reduced by day 7. A significant GSH depletion was observed on days 1 and 3. Brain ROS and lipid peroxidation levels increased significantly on 1 and 3 days and decreased by day 7. The SOD levels in brain showed significantly higher activity on 3 days (4-fold) and 7 days (5-fold) of toxin exposure compared to control. A similar trend was observed with catalase enzyme levels. The gene expression analysis of cNOS and iNOS showed varying levels of expression on different time points of post exposure. MMP-9 expression was significantly high on days 3 and 7 in brain with corresponding alteration in TIMP-1. MMP-2 and TIMP-2 showed no effect. Gene expression analysis of the inflammatory cytokines, IL-1α, IL-1ß, IL-6 and TNF-α showed elevated levels on day 7 in brain. As spleen plays an important role in inflammatory response we analyzed MMP-9, MMP-2 and inflammatory cytokines in spleen. The MMP-9 was activated on day 7. MMP-2 activity was found to be elevated on 3 and 7 days and TIMP-2 mRNA level increased on 1 and 3 days in spleen. Inflammatory cytokines, IL-1 α, IL-1ß, IL-6 and TNF-α showed elevated levels on days 1 and 3 in spleen indicating an early effect in spleen than in brain. In summary, the results of the study showed that the T-2 induced alteration in BBB permeability is mediated through oxidative stress, activation of MMP-9, and proinflammatory cytokines in brain as well as contribution from peripheral tissue spleen.

ROS and CHOP are critical for dibenzylideneacetone to sensitize tumor cells to TRAIL through induction of death receptors and downregulation of cell survival proteins.

Because tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) selectively kills tumor cells, it is being tested in cancer patients. Unfortunately, patients develop resistance to the cytokine, therefore, agents that can sensitize cells to TRAIL are urgently needed. In this study, we investigated whether dibenzylideneacetone (DBA) can sensitize cancer cells to TRAIL and potentiates TRAIL-induced apoptosis. As indicated by accumulation of the membrane phospholipid phosphatidylserine, DNA breaks, intracellular esterase activity, and activation of caspase-8, -9, and -3, we concluded that DBA potentiated TRAIL-induced apoptosis in colon cancer cells. DBA also converted TRAIL resistant-cells to TRAIL-sensitive. When examined for the mechanism, we found that DBA decreased the expression of antiapoptotic proteins and decoy receptor-2 and increased proapoptotic proteins. DBA also induced both death receptor (DR)-5 and DR4. Knockdown of DR5 and DR4 by small interfering RNA (SiRNA) reduced the sensitizing effect of DBA on TRAIL-induced apoptosis. In addition, DBA increased the expression of CHOP proteins. Knockdown of CHOP by siRNA decreased the induction of DBA-induced DR5 expression and apoptosis. Induction of receptors by DBA, however, was p53-independent, as deletion of p53 had no effect on receptor induction. We observed that DBA-induced induction of DR5 and DR4 was mediated through generation of reactive oxygen species (ROS), as N-acetylcysteine blocked the induction of death receptors and suppression of cell survival proteins by DBA. Overall, our results show that DBA potentiates TRAIL-induced apoptosis through downregulation of cell survival proteins and upregulation of death receptors via activation of ROS and CHOP mediated pathways.

Modulation of ROS/MAPK signaling pathways by okadaic acid leads to cell death via, mitochondrial mediated caspase-dependent mechanism.

Okadaic acid (OA) is a specific and potent protein phosphatase inhibitor and tumor promoter. The present study establishes the role of reactive oxygen species (ROS) and mitogen activated protein kinases in cell death induced by okadaic acid. The study showed that okadaic acid is cytotoxic at 10 nM with an IC50 of 100 nM in U-937 cells. The CVDE assay and mitochondrial dehydrogenase assay showed a time dependent cytotoxicity. The phase contrast visualization of the OA treated cells showed the apoptotic morphology and was confirmed with esterase staining for plasma membrane integrity. OA activated caspases-7, 9 and 3, PARP cleavage and induced nuclear damage in a time and dose dependent manner. Compromised mitochondrial membrane potential, release of cytochrome-c and apoptosis inducing factor confirms the involvement of mitochondria. A time dependent decrease in glutathione levels and a dose dependent increase in ROS with maximum at 30 min were observed. ROS scavenger-N-acetyl cysteine, mitochondrial stabilizer-cyclosporin-A, and broad spectrum caspase inhibitor Z-VAD-FMK inhibited the OA induced caspase-3 activation, DNA damage and cell death but caspase-8 inhibitor had no effect. OA activated p38 MAPK and JNK in a time dependent manner, but not ERK½. MAP kinase inhibitors SB203580, SP600125 and PD98059 confirm the role of p38 MAPK and JNK in OA induced caspase-3 activation and cell death. Over all, our results indicate that OA induces cell death by generation of ROS, and activation of p38 MAPK and JNK, and executed through mitochondrial mediated caspase pathway.

Thiocolchicoside exhibits anticancer effects through downregulation of NF-κB pathway and its regulated gene products linked to inflammation and cancer.

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 3ß 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.

Modification of cysteine 179 of IkappaBalpha kinase by nimbolide leads to down-regulation of NF-kappaB-regulated cell survival and proliferative proteins and sensitization of tumor cells to chemotherapeutic agents.

Reverse pharmacology, also called the "bedside to bench" approach, that deals with new uses for a well known molecular entity has been used extensively in cancer drug development to identify novel compounds and delineate their mechanisms of action. Here, we show that nimbolide, a triterpenoid isolated from Azadirachta indica, enhanced the apoptosis induced by inflammatory cytokines and chemotherapeutic agents in tumor cells. This limonoid abrogated the expression of proteins associated with cell survival (Bcl-2, Bcl-xL, IAP-1, and IAP-2), proliferation (cyclin D1), invasion (MMP-9), and angiogenesis (VEGF), all regulated by nuclear factor (NF)-κB. Nimbolide inhibited the activation of NF-κB induced by carcinogens and inflammatory stimuli. Constitutively active NF-κB found in most tumor cells was also inhibited. We found that suppression of NF-κB activation by nimbolide was caused by inhibition of IκB kinase (IKK), which led to suppression of IκBα phosphorylation and degradation, nuclear translocation, DNA binding, and gene transcription. Reducing agent reversed the action of the limonoid, suggesting the involvement of a cysteine residue. Replacement of Cys(179) of IKK-ß with alanine abolished the effect of nimbolide, suggesting that Cys(179) plays a critical role in inhibiting the NF-κB activation. Overall, our results indicate that nimbolide can sensitize tumor cells to chemotherapeutic agents through interaction with IKK, leading to inhibition of NF-κB-regulated proteins.

{Gamma}-tocotrienol inhibits pancreatic tumors and sensitizes them to gemcitabine treatment by modulating the inflammatory microenvironment.

Pancreatic cancers generally respond poorly to chemotherapy, prompting a need to identify agents that could sensitize tumors to treatment. In this study, we investigated the response of human pancreatic cells to γ-tocotrienol (γ-T3), a novel, unsaturated form of vitamin E found in palm oil and rice bran oil, to determine whether it could potentiate the effects of gemcitabine, a standard of care in clinical treatment of pancreatic cancer. γ-T3 inhibited the in vitro proliferation of pancreatic cancer cell lines with variable p53 status and potentiated gemcitabine-induced apoptosis. These effects correlated with an inhibition of NF-κB activation by γ-T3 and a suppression of key cellular regulators including cyclin D1, c-Myc, cyclooxygenase-2 (COX-2), Bcl-2, cellular inhibitor of apoptosis protein, survivin, vascular endothelial growth factor (VEGF), ICAM-1, and CXCR4. In an orthotopic nude mouse model of human pancreatic cancer, p.o. administration of γ-T3 inhibited tumor growth and enhanced the antitumor properties of gemcitabine. Immunohistochemical analysis indicated a correlation between tumor growth inhibition and reduced expression of Ki-67, COX-2, matrix metalloproteinase-9 (MMP-9), NF-κB p65, and VEGF in the tissue. Combination treatment also downregulated NF-κB activity along with the NF-κB-regulated gene products, such as cyclin D1, c-Myc, VEGF, MMP-9, and CXCR4. Consistent with an enhancement of tumor apoptosis, caspase activation was observed in tumor tissues. Overall, our findings suggest that γ-T3 can inhibit the growth of human pancreatic tumors and sensitize them to gemcitabine by suppressing NF-κB-mediated inflammatory pathways linked to tumorigenesis.

Gossypol induces death receptor-5 through activation of the ROS-ERK-CHOP pathway and sensitizes colon cancer cells to TRAIL.

Development of resistance to TRAIL, an apoptosis-inducing cytokine, is one of the major problems in its development for cancer treatment. Thus, pharmacological agents that are safe and can sensitize the tumor cells to TRAIL are urgently needed. We investigated whether gossypol, a BH3 mimetic that is currently in the clinic, can potentiate TRAIL-induced apoptosis. Intracellular esterase activity, sub-G(1) cell cycle arrest, and caspase-8, -9, and -3 activity assays revealed that gossypol potentiated TRAIL-induced apoptosis in human colon cancer cells. Gossypol also down-regulated cell survival proteins (Bcl-x(L), Bcl-2, survivin, XIAP, and cFLIP) and dramatically up-regulated TRAIL death receptor (DR)-5 expression but had no effect on DR4 and decoy receptors. Gossypol-induced receptor induction was not cell type-specific, as DR5 induction was observed in other cell types. Deletion of DR5 by siRNA significantly reduced the apoptosis induced by TRAIL and gossypol. Gossypol induction of the death receptor required the induction of CHOP, and thus, gene silencing of CHOP abolished gossypol-induced DR5 expression and associated potentiation of apoptosis. ERK1/2 (but not p38 MAPK or JNK) activation was also required for gossypol-induced TRAIL receptor induction; gene silencing of ERK abolished both DR5 induction and potentiation of apoptosis by TRAIL. We also found that reactive oxygen species produced by gossypol treatment was critical for TRAIL receptor induction and apoptosis potentiation. Overall, our results show that gossypol enhances TRAIL-induced apoptosis through the down-regulation of cell survival proteins and the up-regulation of TRAIL death receptors through the ROS-ERK-CHOP-DR5 pathway.

Gamma-tocotrienol promotes TRAIL-induced apoptosis through reactive oxygen species/extracellular signal-regulated kinase/p53-mediated upregulation of death receptors.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor superfamily, is in clinical trials for cancer therapy, but its anticancer potential is limited by the development of resistance. We investigated the ability of tocotrienol (T3), an unsaturated vitamin E present in palm oil, rice bran, barley, oats, and wheat germ, to sensitize tumor cells to TRAIL. Results from esterase staining, colony formation, caspase activation, and sub-G(1) cell cycle arrest revealed that gamma-T3 can sensitize human colon cancer cells to TRAIL. When examined for the mechanism, we found that gamma-T3 significantly downregulated the expression of antiapoptotic proteins (c-IAP2 and Bcl-xL). We also found that gamma-T3, but not tocopherol, induced the expression of the TRAIL receptors death receptor (DR)-4 and DR5. This induction was not cell type specific, as upregulation was also found in pancreatic, kidney, and leukemic cells. Upregulation of DRs by gamma-T3 required the production of reactive oxygen species (ROS), and sequestering of ROS abolished both upregulation of the receptors and potentiation of TRAIL-induced apoptosis. Induction of DRs by gamma-T3 also required activation of extracellular signal-regulated kinase 1 (ERK1), as silencing of ERK1 by specific siRNA abrogated the upregulation of TRAIL receptors. Further, induction of DRs by gamma-T3 required the expression of p53 and Bax, as no induction of the receptors was found in colon cancer cells with deletion of these genes. Overall, our results show that gamma-T3 sensitizes tumor cells to TRAIL by upregulating DRs through the ROS/ERK/p53 pathway and by downregulating cell survival proteins.

Cyclodextrin-complexed curcumin exhibits anti-inflammatory and antiproliferative activities superior to those of curcumin through higher cellular uptake.

Curcumin, a yellow pigment present in the spice turmeric (Curcuma longa), has been linked with multiple beneficial activities, but its optimum potential is limited by poor bioavailability, in part due to the lack of solubility in aqueous solvents. To overcome the solubility problem, we have recently developed a novel cyclodextrin complex of curcumin (CDC) and examined here this compound for anti-inflammatory and antiproliferative effects. Using the electrophoretic mobility shift assay, we found that CDC was more active than free curcumin in inhibiting TNF-induced activation of the inflammatory transcription factor NF-kappaB and in suppressing gene products regulated by NF-kappaB, including those involved in cell proliferation (cyclin D1), invasion (MMP-9), and angiogenesis (VEGF). CDC was also more active than free curcumin in inducing the death receptors DR4 and DR5. Annexin V staining, cleavage of caspase-3 and PARP, and DNA fragmentation showed that CDC was more potent than free curcumin in inducing apoptosis of leukemic cells. Antiproliferative assays also demonstrated that CDC was more active than free curcumin in suppressing proliferation of various cancer cell lines. The cyclodextrin vehicle had no effect in these assays. Compared with free curcumin, CDC had a greater cellular uptake and longer half-life in the cells. Overall we demonstrated that CDC had superior attributes compared with free curcumin for cellular uptake and for antiproliferative and anti-inflammatory activities.

Garcinol potentiates TRAIL-induced apoptosis through modulation of death receptors and antiapoptotic proteins.

Whether garcinol, the active component of Garcinia indica, can modulate the sensitivity of cancer cells to TRAIL, a cytokine currently in phase II clinical trial, was investigated. We found that garcinol potentiated TRAIL-induced apoptosis of cancer cells as indicated by intracellular esterase activity, DNA strand breaks, accumulation of the membrane phospholipid phosphatidylserine, mitochondrial activity, and activation of caspase-8, -9, and -3. We found that garcinol, independent of the cell type, induced both of the TRAIL receptors, death receptor 4 (DR4) and DR5. Garcinol neither induced the receptors on normal cells nor sensitized them to TRAIL. Deletion of DR5 or DR4 by small interfering RNA significantly reduced the apoptosis induced by TRAIL and garcinol. In addition, garcinol downregulated various cell survival proteins including survivin, bcl-2, XIAP, and cFLIP, and induced bid cleavage, bax, and cytochrome c release. Induction of death receptors by garcinol was found to be independent of modulation of CCAAT/enhancer-binding protein-homologous protein, p53, bax, extracellular signal-regulated kinase, or c-Jun-NH(2)-kinase. The effect of garcinol was mediated through the generation of reactive oxygen species, in as much as induction of both death receptors, modulation of antiapoptotic and proapoptotic proteins, and potentiation of TRAIL-induced apoptosis were abolished by N-acetyl cysteine and glutathione. Interestingly, garcinol also converted TRAIL-resistant cells into TRAIL-sensitive cells. Overall, our results indicate that garcinol can potentiate TRAIL-induced apoptosis through upregulation of death receptors and downregulation of antiapoptotic proteins. Mol Cancer Ther; 9(4); 856-68. (c)2010 AACR.

Bisdemethylcurcumin and structurally related hispolon analogues of curcumin exhibit enhanced prooxidant, anti-proliferative and anti-inflammatory activities in vitro.

Curcumin, a component of turmeric (Curcuma longa), exhibits anti-inflammatory and anti-proliferative activities through the generation of reactive oxygen species (ROS). Curcumin (diferuloylmethane) contains two hydroxyl, two methoxy and two phenyl groups but how these groups contribute to its activity is poorly understood. We synthesized analogues that varied in inclusion of these groups and compared their activity. We found that bisdemethylcurcumin (BDC) was more potent than curcumin as an anti-inflammatory agent as indicated by suppression of TNF-induced NF-kappaB activation, more potent as an anti-proliferative agent, and more potent in inducing ROS. Hispolon, which lacks one aromatic unit in relation to curcumin, also exhibited enhanced anti-inflammatory and anti-proliferative activities. When synthetic curcumin (Cur-S) was compared with bisdemethylcurcumin (BDC), hispolon, hispolon methyl ether (HME), dehydroxy hispolon (DH), hydroxy hispolon (HH), methoxy hispolon methyl ether (MHME), and methoxy hispolon (MH), we found that following order of anti-inflammatory activity: BDC=Hispolon>HME>HH>Cur-S>MHME>MH>DH; for anti-proliferative: Hispolon>BDC>MHME>Cur-S>MH>HME=HH>DH; and for prooxidant: BDC>Cur-S=MHME>HH>MH+HME>DH (254-1414 mean fluorescence intensity). Thus, dehydroxy hispolon was least potent for all three activities. Overall the results indicate that the substitution of a hydroxyl group for a methoxy group at the meta positions of the phenyl rings in curcumin significantly enhanced the anti-inflammatory activity, and the removal of phenyl ring at the 7(th) position of the heptadiene back bone and addition of hydroxyl group significantly increased the anti-proliferative activity of curcumin.

Thymoquinone poly (lactide-co-glycolide) nanoparticles exhibit enhanced anti-proliferative, anti-inflammatory, and chemosensitization potential.

Thymoquinone (TQ), derived from the medicinal spice Nigella sativa (also called black cumin), has been shown to exhibit anti-inflammatory and anti-cancer activities. In this report we employed polymer-based nanoparticle approach to improve upon its effectiveness and bioavailability. TQ was encapsulated with 97.5% efficiency in biodegradable nanoparticulate formulation based on poly (lactide-co-glycolide) (PLGA) and the stabilizer polyethylene glycol (PEG)-5000. Dynamic laser light scattering and transmission electron microscopy confirmed particle diameter between 150 and 200nm. Electrophoretic gel shift mobility assay showed that TQ nanoparticles (NP) were more active than TQ in inhibiting NF-kappaB activation and in suppressing the expression of cyclin D1, matrix metalloproteinase (MMP)-9, vascular endothelial growth factor (VEGF), those are markers of cell proliferation, metastasis and angiogenesis, respectively. TQ-NP were also more potent than TQ in suppressing proliferation of colon cancer, breast cancer, prostate cancer, and multiple myeloma cells. Esterase staining for plasma membrane integrity revealed that TQ-NP were more potent than TQ in sensitizing leukemic cells to TNF- and paclitaxel-induced apoptosis. Overall our results demonstrate that encapsulation of TQ into nanoparticles enhances its anti-proliferative, anti-inflammatory, and chemosensitizing effects.

NF-kappaB and cancer: how intimate is this relationship.

NF-kappaB, a transcription factor first discovered in 1986, is now known to be closely connected to the process of tumorogenesis based on a multiplicity of evidence. (1) NF-kappaB is activated in response to tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli that account for as much as 95% of all cancers. (2) The transcription factor has been linked with transformation of cells. (3) It is constitutively active in most tumor cells. (4) It has also been linked with the survival of cancer stem cells, an early progenitor cell that has acquired self-renewal potential. (5) NF-kappaB regulates the expression of most anti-apoptotic gene products associated with the survival of the tumor. (6) It also regulates the gene products linked with proliferation of tumors. (7) The transcription factor controls the expression of gene products linked with invasion, angiogenesis, and metastasis of cancer. (8) While most carcinogens activate NF-kappaB, most chemopreventive agents suppress its activation. These observations suggest that NF-kappaB is intimately intertwined with cancer growth and metastasis. The mechanism that leads to constitutive activation of NF-kappaB in hematological, gastrointestinal, genitourinary, gynecological, thoracic head and neck, breast, and skin cancers, and the ways NF-kappaB is activated are the topics of discussion in this review.

Curcumin and cancer cells: how many ways can curry kill tumor cells selectively?

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.