Curcumin-induced antiproliferative and proapoptotic effects in melanoma cells are associated with suppression of IkappaB kinase and nuclear factor kappaB activity and are independent of the B-Raf/mitogen-activated/extracellular signal-regulated protein kinase pathway and the Akt pathway

Liposomal curcumin with and without oxaliplatin: effects on cell growth, apoptosis, and angiogenesis in colorectal cancer

The role of curcumin (diferuloylmethane), a proapoptotic compound, for the treatment of cancer has been an area of growing interest. Curcumin in its free form is poorly absorbed in the gastrointestinal tract and therefore may be limited in its clinical efficacy. Liposome encapsulation of this compound would allow systemic administration. The current study evaluated the preclinical antitumor activity of liposomal curcumin in colorectal cancer. We also compared the efficacy of liposomal curcumin with oxaliplatin, a standard chemotherapy for this malignancy. In vitro treatment with liposomal curcumin induced a dose-dependent growth inhibition [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt] and apoptosis [poly(ADP-ribose) polymerase] in the two human colorectal cancer cell lines tested (LoVo and Colo205 cells). There was also synergism between liposomal curcumin and oxaliplatin at a ratio of 4:1 in LoVo cells in vitro. In vivo, significant tumor growth inhibition was observed in Colo205 and LoVo xenografts, and the growth inhibition by liposomal curcumin was greater than that for oxaliplatin (P < 0.05) in Colo205 cells. Tumors from animals treated with liposomal curcumin showed an antiangiogenic effect, including attenuation of CD31 (an endothelial marker), vascular endothelial growth factor, and interleukin-8 expression by immunohistochemistry. This study establishes the comparable or greater growth-inhibitory and apoptotic effects of liposomal curcumin with oxaliplatin both in vitro and in vivo in colorectal cancer. We are currently developing liposomal curcumin for introduction into the clinical setting.

RETRACTED: Curcumin induces the degradation of cyclin E expression through ubiquitin-dependent pathway and up-regulates cyclin-dependent kinase inhibitors p21 and p27 in multiple human tumor cell lines

Curcumin, a well-known chemopreventive agent, has been shown to suppress the proliferation of a wide variety of tumor cells through a mechanism that is not fully understood. Cyclin E, a proto-oncogene that is overexpressed in many human cancers, mediates the G(1) to S transition, is a potential target of curcumin. We demonstrate in this report a dose- and time-dependent down-regulation of expression of cyclin E by curcumin that correlates with the decrease in the proliferation of human prostate and breast cancer cells. The suppression of cyclin E expression was not cell type dependent as down-regulation occurred in estrogen-positive and -negative breast cancer cells, androgen-dependent and -independent prostate cancer cells, leukemia and lymphoma cells, head and neck carcinoma cells, and lung cancer cells. Curcumin-induced down-regulation of cyclin E was reversed by proteasome inhibitors, lactacystin and N-acetyl-L-leucyl-L-leucyl-L-norleucinal, suggesting the role of ubiquitin-dependent proteasomal pathway. We found that curcumin enhanced the expression of tumor cyclin-dependent kinase (CDK) inhibitors p21 and p27 as well as tumor suppressor protein p53 but suppressed the expression of retinoblastoma protein. Curcumin also induced the accumulation of the cells in G1 phase of the cell cycle. Overall, our results suggest that proteasome-mediated down-regulation of cyclin E and up-regulation of CDK inhibitors may contribute to the antiproliferative effects of curcumin against various tumors.

Mechanisms of curcumin- and EGF-receptor related protein (ERRP)-dependent growth inhibition of colon cancer cells

Numerous dietary and pharmacological agents have been proposed as alternative strategies for treatment and prevention of colorectal cancer. Curcumin, an active ingredient of turmeric, that inhibits growth of malignant neoplasms, has a promising role in the prevention and treatment of colorectal cancer. EGF-R related protein (ERRP), a recently identified pan-erbB inhibitor, is a potential therapeutic agent for colorectal cancer. Here we examine whether curcumin together with ERRP will cause a greater inhibition of growth of colon cancer cells than either agent alone and the mechanisms of this inhibition. Human colon cancer HCT-116 or HT-29 cells were incubated with increasing doses of curcumin (up to 10 microM) or ERRP (up to 5 microg/ml), or a combination of both for 48 h. We observed that the cell growth inhibition and stimulation of apoptosis in response to the combinatorial treatment was significantly greater than that caused by either agent alone. These changes were associated with decreased activation (tyrosine phosphorylation) of EGFR, ErbB-2, ErbB-3, and/or IGF-1R. Whereas curcumin inhibited constitutive activation of both EGFR and IGF-1R, ERRP decreased activation of EGFR, ErbB-2, and ErbB-3 but had no effect on IGF-1R. Further, the combination therapy caused a greater attenuation of downstream effectors such as NF-kappaB, Akt and BAD activation, and down-regulation of procaspase-3 than that noted with either agent alone. The superior effects of the combinatorial treatment could partly be attributed to inhibition of constitutive activation of EGFRs and IGF-1R signaling pathways.

Cyclooxygenase inhibition and hyperthermia for the potentiation of the cytotoxic response in ovarian cancer cells

OBJECTIVES

The progression of chemotherapy-resistant cancer confers poor prognosis and decreases overall survival in ovarian cancer patients. Adjuvants to traditional chemotherapy regimens have become attractive modalities for the clinical treatment of refractory or resistant ovarian cancer. We evaluated whether the addition of NSAID to hyperthermic chemotherapy would increase cytotoxicity in cisplatin- and taxane-treated ovarian cancer cells.

METHODS

Western blot analysis was utilized to determine COX-2 protein expression levels in the 2008, cisplatin-sensitive, and C13*, cisplatin-resistant, cell lines. PGE2 levels were determined and analyzed as a function of cyclooxygenase activity by LC/MS/MS. Cells were treated with cisplatin, docetaxel or paclitaxel in combination with either NS-398 or sulindac sulfide at 37 degrees C, 41 degrees C or 43 degrees C. Cell viability was determined by a MTS cell proliferation assay.

RESULTS

Both cell lines expressed COX-2 protein, and NS-398 and sulindac sulfide effectively blocked PGE2 production. The addition of a NSAID to cisplatin treatment in 2008 and C13* cells offered enhanced cytotoxicity and this effect was further enhanced at 41 degrees C. In docetaxel-treated 2008 cells, both NS-398 and sulindac sulfide offered enhanced cell kill; however, this result was not observed in paclitaxel-treated cells. Hyperthermia appeared to play no additional role in taxane cytotoxicity enhancement, however no antagonism was detected.

CONCLUSIONS

Our results suggest that the combination treatment (cisplatin or docetaxel in combination with NSAID) cause a dose-dependent enhancement of cytotoxicity. Hyperthermia may improve the results of intraperitoneal cisplatin therapy, thus warranting further evaluation in clinical studies.

Coordinated upregulation of COX-2 and NF-kappaB is a steady feature of laryngeal carcinogenesis

BACKGROUND/AIMS

Laryngeal cancer is the endpoint of a multistage process involving hyperplastic and dysplastic lesions, not adequately defined in their molecular aspect. Our objective was to evaluate the expression of the prostaglandin-synthesizing enzyme cyclooxygenase-2 (COX-2) and the chief transcription factor nuclear factor-kappaB (NF-kappaB) in laryngeal carcinomas and their precursors, as well as to explore any association between the two molecules.

METHODS

We performed paraffin section immunohistochemistry for COX-2 and the p65 subunit of NF-kappaB, in tissues from 129 patients with tumors or premalignancies. p65 cytoplasmic and nuclear immunostaining were listed individually.

RESULTS

COX-2 was positively correlated with histopathological grading from normal mucosa to carcinomas (Spearman's coefficient r(s) = 0.286, p < 0.001). No association was revealed between COX-2 expression and tumor grade. p65 immunoreactivity, both of cytoplasmic and nuclear origin, increased along the carcinogenesis course, manifesting highest expression in invasive cancer (r(s) = 0.419, p < 0.001 and r(s) = 0.241, p < 0.001, respectively). Again, tumor grade had no influence on expression. COX-2 and p65 cytoplasmic, but no nuclear, expression showed a positive correlation (r(s) = 0.352, p < 0.001).

CONCLUSIONS

This study demonstrates that lesional advance in the larynx towards cancer is marked by ongoing upregulation of COX-2 and NF-kappaB. Synchronism between individual expressions may denote a regulatory role of the latter in COX-2 transactivation.

Dimethylfumarate impairs melanoma growth and metastasis

Dimethylfumarate (DMF) inhibits signals transmitted by Rel proteins and is used for the treatment of inflammatory skin diseases such as psoriasis, but potential effects of DMF on tumor progression have yet not been analyzed. We show that DMF reduced melanoma growth and metastasis in severe combined immunodeficient mouse models. To identify targets of DMF action, we analyzed mRNA expression in DMF-treated melanomas by gene chip arrays. Using BiblioSphere software for data analysis, significantly regulated genes were mapped to Gene Ontology terms cell death, cell growth, and cell cycle. Indeed, we found that DMF inhibited proliferation of human melanoma cells A375 and M24met in vitro. The cell cycle was arrested at the G(2)-M boundary. Moreover, DMF was proapoptotic, as shown by cell cycle analysis and by Annexin V and Apo2.7 staining. These results were confirmed in vivo. DMF reduced proliferation rates of tumor cells as assessed by Ki-67 immunostaining and increased apoptosis as assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining. In conclusion, DMF is antiproliferative and proapoptotic and reduces melanoma growth and metastasis in animal models.

"Spicing up" of the immune system by curcumin

Curcumin (diferuloylmethane) is an orange-yellow component of turmeric (Curcuma longa), a spice often found in curry powder. Traditionally known for its an antiinflammatory effects, curcumin has been shown in the last two decades to be a potent immunomodulatory agent that can modulate the activation of T cells, B cells, macrophages, neutrophils, natural killer cells, and dendritic cells. Curcumin can also downregulate the expression of various proinflammatory cytokines including TNF, IL-1, IL-2, IL-6, IL-8, IL-12, and chemokines, most likely through inactivation of the transcription factor NF-kappaB. Interestingly, however, curcumin at low doses can also enhance antibody responses. This suggests that curcumin's reported beneficial effects in arthritis, allergy, asthma, atherosclerosis, heart disease, Alzheimer's disease, diabetes, and cancer might be due in part to its ability to modulate the immune system. Together, these findings warrant further consideration of curcumin as a therapy for immune disorders.

"Spicing up" of the immune system by curcumin

Curcumin (diferuloylmethane) is an orange-yellow component of turmeric (Curcuma longa), a spice often found in curry powder. Traditionally known for its an antiinflammatory effects, curcumin has been shown in the last two decades to be a potent immunomodulatory agent that can modulate the activation of T cells, B cells, macrophages, neutrophils, natural killer cells, and dendritic cells. Curcumin can also downregulate the expression of various proinflammatory cytokines including TNF, IL-1, IL-2, IL-6, IL-8, IL-12, and chemokines, most likely through inactivation of the transcription factor NF-kappaB. Interestingly, however, curcumin at low doses can also enhance antibody responses. This suggests that curcumin's reported beneficial effects in arthritis, allergy, asthma, atherosclerosis, heart disease, Alzheimer's disease, diabetes, and cancer might be due in part to its ability to modulate the immune system. Together, these findings warrant further consideration of curcumin as a therapy for immune disorders.

Effect of Curcumin Treatment on Protein Phosphorylation in K562 Cells

Deregulation of signaling pathways is a common feature observed in human cancers and other diseases. Therefore, there is a strong need for compounds that are able to modulate or inactivate upregulated signaling events. Natural compounds extracted from plants have long been used and still present a dynamic domain in the research of new therapeutic tools. Among those molecules, curcumin was already described for its antioxidative, anti-inflammatory, and antiseptic properties. Many actions of curcumin target proteins and kinases implicated in the signaling pathways. However, the effects described depend on the treatment conditions used, as well as the cell line studied, and these features vary strongly from one study to the other. During this work, we evaluated the effect of one curcumin treatment (20 muM, 48 h) on the phosphorylation of a number of proteins and kinases in the human chronic myelogenous leukemia cell line K562. These results allow to compare the results obtained in one condition on various proteins.

Curcumin down regulates smokeless tobacco-induced NF-κB activation and COX-2 expression in human oral premalignant and cancer cells

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.

Adenine nucleotides inhibit proliferation of the human lung adenocarcinoma cell line LXF-289 by activation of nuclear factor kappaB1 and mitogen-activated protein kinase pathways

Extracellular nucleotides have a profound role in the regulation of the proliferation of diseased tissue. We studied how extracellular nucleotides regulate the proliferation of LXF-289 cells, the adenocarcinoma-derived cell line from human lung bronchial tumor. ATP and ADP strongly inhibited LXF-289 cell proliferation. The nucleotide potency profile was ATP = ADP = ATPgammaS > > UTP, UDP, whereas alpha,beta-methylene-ATP, beta,gamma-methylene-ATP, 2',3'-O-(4-benzoylbenzoyl)-ATP, AMP and UMP were inactive. The nucleotide potency profile and the total blockade of the ATP-mediated inhibitory effect by the phospholipase C inhibitor U-73122 clearly show that P2Y receptors, but not P2X receptors, control LXF-289 cell proliferation. Treatment of proliferating LXF-289 cells with 100 microm ATP or ADP induced significant reduction of cell number and massive accumulation of cells in the S phase. Arrest in S phase is also indicated by the enhancement of the antiproliferative effect of ATP by coapplication of the cytostatic drugs cisplatin, paclitaxel and etoposide. Inhibition of LXF-289 cell proliferation by ATP was completely reversed by inhibitors of extracellular signal related kinase-activating kinase/extracellular signal related kinase 1/2 (PD98059, U0126), p38 mitogen-activated protein kinase (SB203508), phosphatidylinositol-3-kinase (wortmannin), and nuclear factor kappaB1 (SN50). Western blot analysis revealed transient activation of p38 mitogen-activated protein kinase, extracellular signal-related kinase 1/2, and nuclear factor kappaB1 and possibly new formation of p50 from its precursor p105. ATP-induced attenuation of LXF-289 cell proliferation was accompanied by transient translocation of p50 nuclear factor kappaB1 and extracellular signal-related kinase 1/2 to the nucleus in a similar time period. In summary, inhibition of LXF-289 cell proliferation is mediated via P2Y receptors by activation of multiple mitogen-activated protein kinase pathways and nuclear factor kappaB1, arresting the cells in the S phase.

Apoptosis and melanoma: how new insights are effecting the development of new therapies for melanoma

PURPOSE OF REVIEW

Melanoma has proven resistant to most available chemotherapy and immunotherapy. Despite a range of different biochemical targets, most agents kill cancer cells by induction of apoptosis.

RECENT FINDINGS

Investigation of this process has provided insights into the resistance mechanisms in cancer cells and to development of a range of new agents that target apoptosis pathways. These include agents which inhibit antiapoptotic B cell lymphoma-2 family proteins and inhibitor of apoptosis proteins. In addition, a range of signal pathway inhibitors have become available that are able to inhibit signal pathways known to be associated with resistance to apoptosis.

SUMMARY

Evaluation of most of these reagents are at a preclinical level but studies on some pathway inhibitors have passed from phase II into phase III studies. Similarly, evaluation of antisense reagents are at an advanced stage. These early trials show much promise and suggest this approach to development of new therapies will lead to much needed advances in treatment of this disease.

Combined effect of proteasome and calpain inhibition on cisplatin-resistant human melanoma cells

Resistance of tumor cells to cisplatin is a common feature frequently encountered during chemotherapy against melanoma caused by various known and unknown mechanisms. To overcome drug resistance toward cisplatin, a targeted treatment using alternative agents, such as proteasome inhibitors, has been investigated. This combination could offer a new therapeutic approach. Here, we report the biological effects of proteasome inhibitors on the parental cisplatin-sensitive MeWo human melanoma cell line and its cisplatin-resistant MeWo(cis1) variant. Our experiments show that proteasome inhibitor treatment of both cell lines impairs cell viability at concentrations that are not toxic to primary human fibroblasts in vitro. However, compared with the parental MeWo cell line, significantly higher concentrations of proteasome inhibitor are required to reduce cell viability of MeWo(cis1) cells. Moreover, whereas proteasome activity was inhibited to the same extent in both cell lines, IkappaBalpha degradation and nuclear factor-kappaB (NF-kappaB) activation in MeWo(cis1) cells was proteasome inhibitor independent but essentially calpain inhibitor sensitive. In support, a calpain-specific inhibitor impaired NF-kappaB activation in MeWo(cis1) cells. Here, we show that cisplatin resistance in MeWo(cis1) is accompanied by a change in the NF-kappaB activation pathway in favor of calpain-mediated IkappaBalpha degradation. Furthermore, combined exposure to proteasome and calpain inhibitor resulted in additive effects and a strongly reduced cell viability of MeWo(cis1) cells. Thus, combined strategies targeting distinct proteolytic pathways may help to overcome mechanisms of drug resistance in tumor cells.

NF-kappaB activation in melanoma

Metastatic melanoma is an aggressive skin cancer that is notoriously resistant to current cancer therapies. In human melanoma, nuclear factor-kappa B (NF-kappaB) is upregulated, leading to the deregulation of gene transcription. In this review, we discuss (i) the relationship between gene alteration in melanoma and upregulation of NF-kappaB, (ii) mechanisms by which activated NF-kappaB switch from pro-apoptotic to anti-apoptotic functions in melanoma and (iii) autocrine mechanisms that promote constitutive activation of NF-kappaB in metastatic melanoma.

Targeting angiogenesis with integrative cancer therapies

An integrative approach for managing a patient with cancer should target the multiple biochemical and physiological pathways that support tumor development while minimizing normal tissue toxicity. Angiogenesis is a key process in the promotion of cancer. Many natural health products that inhibit angiogenesis also manifest other anticancer activities. The authors will focus on natural health products (NHPs) that have a high degree of antiangiogenic activity but also describe some of their many other interactions that can inhibit tumor progression and reduce the risk of metastasis. NHPs target various molecular pathways besides angiogenesis, including epidermal growth factor receptor (EGFR), the HER-2/neu gene, the cyclooxygenase-2 enzyme, the NF-kB transcription factor, the protein kinases, Bcl-2 protein, and coagulation pathways. The herbalist has access to hundreds of years of observational data on the anticancer activity of many herbs. Laboratory studies are confirming the knowledge that is already documented in traditional texts. The following herbs are traditionally used for anticancer treatment and are antiangiogenic through multiple interdependent processes that include effects on gene expression, signal processing, and enzyme activities: Artemisia annua (Chinese wormwood), Viscum album (European mistletoe), Curcuma longa (turmeric), Scutellaria baicalensis (Chinese skullcap), resveratrol and proanthocyanidin (grape seed extract), Magnolia officinalis (Chinese magnolia tree), Camellia sinensis (green tea), Ginkgo biloba, quercetin, Poria cocos, Zingiber officinale (ginger), Panax ginseng, Rabdosia rubescens (rabdosia), and Chinese destagnation herbs. Quality assurance of appropriate extracts is essential prior to embarking on clinical trials. More data are required on dose response, appropriate combinations, and potential toxicities. Given the multiple effects of these agents, their future use for cancer therapy probably lies in synergistic combinations. During active cancer therapy, they should generally be evaluated in combination with chemotherapy and radiation. In this role, they act as biological response modifiers and adaptogens, potentially enhancing the efficacy of the so-called conventional therapies. Their effectiveness may be increased when multiple agents are used in optimal combinations. New designs for trials to demonstrate activity in human subjects are required. Although controlled trials might be preferred, smaller studies with appropriate end points and surrogate markers for antiangiogenic response could help prioritize agents for the larger resource-intensive phase 3 trials.

What about chemoprevention for melanoma?

PURPOSE OF REVIEW

This paper aims to critically review the potential for a chemoprevention strategy in melanoma, and to discuss new data on candidate chemoprevention agents, as chemoprevention has been suggested as an unexplored approach in melanoma.

RECENT FINDINGS

A strong scientific rationale, established long-term safety of candidate agents, and a systematic step-wise approach to chemoprevention agent development are all critical for melanoma chemoprevention research. Among potential agents, the lipid-lowering drugs, the statins, satisfy these prerequisites.

SUMMARY

Chemoprevention of cutaneous melanoma can become a valid strategy complementing current prevention approaches, as long as these important prerequisites are taken into consideration.

From traditional Ayurvedic medicine to modern medicine: identification of therapeutic targets for suppression of inflammation and cancer

Cancer is a hyperproliferative disorder that involves transformation, dysregulation of apoptosis, proliferation, invasion, angiogenesis and metastasis. Extensive research during the last 30 years has revealed much about the biology of cancer. Drugs used to treat most cancers are those that can block cell signalling, including growth factor signalling (e.g., epidermal growth factor); prostaglandin production (e.g., COX-2); inflammation (e.g., inflammatory cytokines: NF-kappaB, TNF, IL-1, IL-6, chemokines); drug resistance gene products (e.g., multi-drug resistance); cell cycle proteins (e.g., cyclin D1 and cyclin E); angiogenesis (e.g., vascular endothelial growth factor); invasion (e.g., matrix metalloproteinases); antiapoptosis (e.g., bcl-2, bcl-X(L), XIAP, survivin, FLIP); and cellular proliferation (e.g., c-myc, AP-1, growth factors). Numerous reports have suggested that Ayurvedic plants and their components mediate their effects by modulating several of these recently identified therapeutic targets. However, Ayurvedic medicine requires rediscovery in light of our current knowledge of allopathic (modern) medicine. The focus of this review is to elucidate the Ayurvedic concept of cancer, including its classification, causes, pathogenesis and prevention; surgical removal of tumours; herbal remedies; dietary modifications; and spiritual treatments.

Current strategies in overcoming resistance of cancer cells to apoptosis melanoma as a model

Most anticancer agents mediate their effects through common pathways which induce apoptosis or in some cases necrosis of cancer cells. The apoptotic pathways are regulated by Bcl-2 family proteins, which include both pro- and anti-apoptotic members. Much is known about the interactions of these proteins involved in apoptosis and this information is being utilized in the development of new reagents that may be used to treat patients with cancers. The inhibitor of apoptosis family of proteins constitute a second group of proteins which inhibit the effector caspases. Reagents that inhibit their activity are also under development. Resistance of cancer cells to treatment can in many instances be attributed to activation of intracellular signal pathways involved in survival, such as the Ras-Raf-MEK-ERK1/2 or the P13K-Akt pathway. Again, much has been learned about the control of these pathways and their activation of resistance mechanisms. Inhibitors of such pathways are being evaluated in preclinical and clinical studies and are showing promise as a new class of anticancer agents. Much of the progress in future studies will likely depend on the ability to target these new treatments to particular subgroups of patients with tumor characteristics that make them responsive to the agents in question.