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

Modulation of inflammatory signaling pathways by phytochemicals in ovarian cancer

Inflammation has been suggested to be involved in cancer development and progression. Many clinical and experimental studies have shown that inflammation could contribute to ovarian carcinogenesis through activation of the NF-κB and AP-1 pathways by chronic inflammatory mediators. Phytochemicals, which are natural compounds derived from fruits and vegetables, have shown anti-inflammatory and anti-cancer effects. Due to their relatively low toxicity and easy accessibility, phytochemicals have been investigated for their chemopreventive potential against various cancers. In this review, we discuss the role of phytochemicals in preventing ovarian cancer through anti-inflammatory mechanisms.

Small interfering RNA targeting IKKβ prevents renal ischemia-reperfusion injury in rats

The transcription factor NF-κB has been found critical to the pathogenesis of renal ischemia-reperfusion injury, which is a major cause of acute kidney injury (AKI). Activation of NF-κB is dependent upon the activation of the specific inhibitory κB kinase (IKK) subunit IKKβ. Here, we investigate whether small interfering RNA (siRNA) targeting IKKβ protects rats from renal ischemia- reperfusion injury in vivo. Renal ischemia-reperfusion injury was induced by clamping the renal artery for 45 min. Rats were treated before ischemia with IKKβ siRNA or scrambled siRNA, administered by renal artery injection. Treated animals were evaluated for renal IKKβ protein and mRNA expression, blood biochemistry, tissue histopathology, NF-κB/DNA binding activity, and expression of two downstream inflammatory cytokines, neutrophil gelatinase-associated lipocalin (NGAL) and IL-18. A local injection of IKKβ siRNA resulted in inhibition of renal IKKβ gene expression, NF-κB/DNA binding activity, and expression of NGAL and IL-18. Rats pretreated with IKKβ siRNA had significantly less blood urea nitrogen and serum creatinine levels and less renal tubular damage scores. Consequently, our data confirm that targeted silencing of IKKβ using siRNA substantially diminishes kidney injury and inflammation following ischemia-reperfusion.

Curcumin enhances dasatinib-induced inhibition of growth and transformation of colon cancer cells

Colorectal cancer is the third most common form of malignancy, behind prostate and lung cancers. Despite recent advances in medicine, mortality from colorectal cancer remains high, highlighting the need for improved therapies. Numerous studies have demonstrated increased activation of EGFR and its family members (EGFRs), IGF-1R as well as c-Src in colorectal cancer. The current study was undertaken to examine the effectiveness of combination therapy of dasatinib (BMS-354825; Bristol-Myers Squibb), a highly specific inhibitor of Src family kinases (SFK) and a nontoxic dietary agent; curcumin (diferuloylmethane), in colorectal cancer in in vitro and in vivo experimental models. For the latter, we utilized C57BL/6 APC(Min+/-) mice. Initial in vitro studies revealed synergistic interactions between the two agents. Additionally, we have observed that combination treatment causes a much greater inhibition of the following metastatic processes than either agent alone: (i) colony formation, (ii) invasion through extracellular matrix and (iii) tubule formation by endothelial cells. Dasatinib affects the cell adhesion phenotype of colon cancer HCT-116 cells whereas the combination therapy enhances this effect to a greater extent. Preclinical investigation revealed that the combination therapy to be highly effective causing an over 95% regression of intestinal adenomas in Apc(Min+/-) mice, which could be attributed to decreased proliferation and increased apoptosis. In conclusion, our data suggest that combination treatment of dasatinib and curcumin could be a potential therapeutic strategy for colorectal cancer.

Femtosecond Fluorescence Upconversion Investigations on the Excited-State Photophysics of Curcumin

The demonstration of curcumin as a photodynamic therapy agent has generated a high level of interest in understanding the photoinduced chemical and physical properties of this naturally occurring, yellow-orange medicinal compound. Important photophysical processes that may be related to photodynamic therapy effects including excited-state intramolecular hydrogen atom transfer (ESIHT) occur within the femtosecond to picosecond time scales. Femtosecond fluorescence upconversion spectroscopy has sufficient time resolution to resolve and investigate these important photophysical processes. In this review, recent advances in using femtosecond fluorescence upconversion to reveal ultrafast solvation and ESIHT of curcumin are presented. The excited-state photophysics of curcumin has been investigated in alcohols and micellar solutions. The results of curcumin in methanol and ethylene glycol reveal the presence of two decay components in the excited-state kinetics with time scales of 12–20 ps and ∼100 ps. Similarly, in a micellar solution, biphasic kinetics are present with the fast decay component having a time constant of 3–8 ps, the slow decay component 50–80 ps. Deuteration of curcumin in both media leads to a pronounced isotope effect in the slow decay component, which suggests that ESIHT is an important photophysical process on this time scale. The results of multiwavelength fluorescence upconversion studies show that the fast component in the excited-state kinetics is due to ultrafast solvation. These advances form a part of the continuing efforts to elucidate the photodynamic therapy properties of curcumin.

The in vitro stability and in vivo pharmacokinetics of curcumin prepared as an aqueous nanoparticulate formulation

Curcumin, the natural anticancer drug and its optimum potential is limited due to lack of solubility in aqueous solvent, degradation at alkaline pH and poor tissue absorption. In order to enhance its potency and improve bioavailability, we have synthesized curcumin loaded nanoparticulate delivery system. Unlike free curcumin, it is readily dispersed in aqueous medium, showing narrow size distribution 192 nm ranges (as observed by microscope) with biocompatibility (confocal studies and TNF-alpha assay). Furthermore, it displayed enhanced stability in phosphate buffer saline by protecting encapsulated curcumin against hydrolysis and biotransformation. Most importantly, nanoparticulate curcumin was comparatively more effective than native curcumin against different cancer cell lines under in vitro condition with time due to enhanced cellular uptake resulting in reduction of cell viability by inducing apoptosis. Molecular basis of apoptosis studied by western blotting revealed blockade of nuclear factor kappa B (NFkappaB) and its regulated gene expression through inhibition of IkappaB kinase and Akt activation. In mice, nanoparticulate curcumin was more bioavailable and had a longer half-life than native curcumin as revealed from pharmacokinetics study. Thus, the results demonstrated nanoparticulate curcumin may be useful as a potential anticancer drug for treatment of various malignant tumors.

Curcumin's effect on intestinal inflammation and tumorigenesis in the ApcMin/+ mouse

Curcumin's benefits on tumorigenesis are thought to be mediated by its antiinflammatory activity; however, these effects have not been well characterized in a mouse model of colon cancer. We examined the effects of curcumin on intestinal inflammation in the Apc(Min/+) mouse. Apc(Min/+) mice were given a placebo or curcumin (2%) diet from 4 to 18 weeks of age (n = 10/group). C57BL/6 mice were used as a wild-type control (n = 10/group). Intestines were analyzed for polyp burden (sections 1, 4, and 5) and for mRNA expression, and concentration of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and chemokine ligand 2 (CCL2) (sections 2 and 3). Plasma was collected for concentration of CCL2. Curcumin decreased total intestinal polyps by 75% (P < 0.05) in all size categories [>2 mm (65%), 1-2 mm (72%), <1 mm (82%); P < 0.05]. mRNA expression of IL-1β, IL-6, tumor necrosis factor-α, and CCL2 was elevated (P < 0.05) and curcumin blunted this increase (P < 0.05). Protein concentration of IL-1β, IL-6 (section 3), and CCL2 was increased (P < 0.05) and curcumin reduced this response for IL-1β (section 2) and CCL2 (P < 0.05). Curcumin also offset the increase in plasma CCL2 (P < 0.05). The benefits of curcumin in colon cancer may be at least in part mediated by its antiinflammatory activity.

Synthesis and in vitro/in vivo anti-cancer evaluation of curcumin-loaded chitosan/poly(butyl cyanoacrylate) nanoparticles

We have synthesized novel cationic poly(butyl) cyanoacrylate (PBCA) nanoparticles coated with chitosan, formulation of curcumin nanoparticles. The size and zeta potential of prepared curcumin nanoparticles were about 200 nm and +29.11 mV, respectively with 90.04% encapsulation efficiency. The transmission electron microscopy (TEM) study revealed the spherical nature of the prepared nanoparticles along with confirmation of particle size. Curcumin nanoparticles demonstrate comparable in vitro therapeutic efficacy to free curcumin against a panel of human hepatocellular cancer cell lines, as assessed by cell viability (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide assay [MTT assay]) and proapoptotic effects (annexin V/propidium iodide staining). In vivo, curcumin nanoparticles suppressed hepatocellular carcinoma growth in murine xenograft models and inhibited tumor angiogenesis. The curcumin nanoparticles' mechanism of action on hepatocellular carcinoma cells is a mirror that of free curcumin.

Coordinated increased expression of Cyclooxygenase2 and nuclear factor κB is a steady feature of urinary bladder carcinogenesis

OBJECTIVES

The inescapable relationship between chronic inflammation and carcinogenesis has long been established. Our objective was to investigate COX-2 and NF-κB immunohistochemical expression in a large series of normal epithelium and bladder carcinomas.

METHODS

Immunohistochemical methodology was performed on formalin-fixed, paraffin-embedded sections from urinary bladder carcinomas of 140 patients (94 males and 46 females with bladder carcinomas).

RESULTS

COX-2 expression is increased in the cytoplasm of bladder cells, during loss of cell differentiation (r(s) = 0.61, P-value < .001) and in muscle invasive carcinomas (P-value < .001). A strong positive association between tumor grade and nuclear expression of NFκB has been established. A positive correlation between COX-2 and nuclear NFκB immunoreactivity was observed.

CONCLUSIONS

The possible coordinated upregulation of NFκB and COX-2, during bladder carcinogenesis, indicates that agents inhibitors of these two molecules may represent a possible new treatment strategy, by virtue of their role in bladder carcinogenesis.

The small molecule curcumin analog FLLL32 induces apoptosis in melanoma cells via STAT3 inhibition and retains the cellular response to cytokines with anti-tumor activity

Background

We characterized the biologic effects of a novel small molecule STAT3 pathway inhibitor that is derived from the natural product curcumin. We hypothesized this lead compound would specifically inhibit the STAT3 signaling pathway to induce apoptosis in melanoma cells.

Results

FLLL32 specifically reduced STAT3 phosphorylation at Tyr705 (pSTAT3) and induced apoptosis at micromolar amounts in human melanoma cell lines and primary melanoma cultures as determined by annexin V/propidium iodide staining and immunoblot analysis. FLLL32 treatment reduced expression of STAT3-target genes, induced caspase-dependent apoptosis, and reduced mitochondrial membrane potential. FLLL32 displayed specificity for STAT3 over other homologous STAT proteins. In contrast to other STAT3 pathway inhibitors (WP1066, JSI-124, Stattic), FLLL32 did not abrogate IFN-γ-induced pSTAT1 or downstream STAT1-mediated gene expression as determined by Real Time PCR. In addition, FLLL32 did not adversely affect the function or viability of immune cells from normal donors. In peripheral blood mononuclear cells (PBMCs), FLLL32 inhibited IL-6-induced pSTAT3 but did not reduce signaling in response to immunostimulatory cytokines (IFN-γ, IL 2). Treatment of PBMCs or natural killer (NK) cells with FLLL32 also did not decrease viability or granzyme b and IFN-γ production when cultured with K562 targets as compared to vehicle (DMSO).

Conclusions

These data suggest that FLLL32 represents a lead compound that could serve as a platform for further optimization to develop improved STAT3 specific inhibitors for melanoma therapy.

Systematic analysis of the antiproliferative effects of novel and standard anticancer agents in rhabdoid tumor cell lines

Rhabdoid tumors are highly aggressive pediatric malignancies. Although the prognosis of children with rhabdoid tumors has improved, it still remains dismal and long-term survivors suffer from severe side effects of current therapeutic approaches. The objective of our study was to explore the toxicity of standard and novel anticancer drugs against rhabdoid tumors in vitro and to prioritize them for future preclinical and clinical studies. Antitumor activity of 10 standard anticancer drugs (doxorubicin, idarubicin, mitoxantrone, actinomycin D, temozolomide, carmustine, oxaliplatin, vinorelbine, methotrexate, thiotepa), five target-specific drugs (sorafenib, imatinib, roscovitine, rapamycin, ciglitazone) and two herbal compounds (curcumin and apigenin) was assessed by a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell proliferation assay on three rhabdoid tumor cell lines, A204, G401, and BT16, derived from different anatomical sites. Comparable with their high clinical activity, anthracyclines inhibited tumor cell proliferation by 50% (GI50) in the nanomolar range. Actinomycin D exhibited the lowest GI50 values overall ranging from 2.8x10(-6) nmol/l for G401 to 3.8 nmol/l for A204 cells while thiotepa was the only alkylating drug that inhibited tumor cell growth in clinically relevant concentrations. Target-specific drugs, such as sorafenib, roscovitine, and rapamycin, showed promising results as well. In this report, we show for the first time that apigenin and curcumin effectively inhibit rhabdoid tumor cell growth. Supporting earlier reports we conclude that cyclin D1 seems to be an excellent target in the treatment of rhabdoid tumors. Idarubicin or mitoxantrone represent potent alternatives to doxorubicin, and vinorelbine may substitute vincristine in future clinical trials.

Curcuminoids activate p38 MAP kinases and promote UVB-dependent signalling in keratinocytes

Curcuminoids exhibit anti-proliferative properties in many cell lines by modulating signalling pathways to inhibit cell growth. However, the specific effects of curcuminoids on human keratinocytes are not well defined, and this situation impairs mechanistic thinking regarding potential therapeutic uses. We hypothesized that curcuminoids would modulate key growth regulatory pathways in keratinocytes to inhibit cell proliferation. To test this hypothesis, the effects of curcumin and tetrahydrocurcumin (THC) on mitogen-activated protein (MAP) kinase signalling in keratinoctyes were determined. Primary human keratinocytes treated with curcumin or THC demonstrated decreased activation of p44/42 MAP kinases but increased levels of activated p38 MAP kinases. These data suggest that curcuminoids specifically activate stress-induced MAP kinases while inhibiting mitogen-induced MAP kinases. Curcuminoids also promote the phosphorylation of p53 on serine 15 in a dose-dependent and p38-dependent manner, suggesting that these compounds may activate p53. The effects of curcuminoids on keratinocytes mirrored some aspects of UVB and could be inhibited by N-acetylcysteine, suggesting that these compounds activate p38 through a mechanism that involves glutathione depletion. Both curcuminoids induced G2/M block and inhibited keratinocyte growth, and THC increased cellular levels of p21, a known p53 transcriptional target. These data demonstrate that curcuminoids can differentially regulate MAP kinases to inhibit keratinocyte growth while inducing p21. Curcuminoids also synergize with UVB to enhance p53 phosphorylation. The findings provide a rationale for testing curcuminoids in disorders associated with impaired p53 function or in which UVB-treatment is efficacious.

Curcumin induces the tolerogenic dendritic cell that promotes differentiation of intestine-protective regulatory T cells

The gut is home to a large number of Treg, with both CD4(+) CD25(+) Treg and bacterial antigen-specific Tr1 cells present in normal mouse intestinal lamina propria. It has been shown recently that intestinal mucosal DC are able to induce Foxp3(+) Treg through production of TGF-beta plus retinoic acid (RA). However, the factors instructing DC toward this mucosal phenotype are currently unknown. Curcumin has been shown to possess a number of biologic activities including the inhibition of NF-kappaB signaling. We asked whether curcumin could modulate DC to be tolerogenic whose function could mimic mucosal DC. We report here that curcumin modulated BM-derived DC to express ALDH1a and IL-10. These curcumin-treated DC induced differentiation of naïve CD4(+) T cells into Treg resembling Treg in the intestine, including both CD4(+)CD25(+) Foxp3(+) Treg and IL-10-producing Tr1 cells. Such Treg induction required IL-10, TGF-beta and retinoic acid produced by curcumin-modulated DC. Cell contact as well as IL-10 and TGF-beta production were involved in the function of such induced Treg. More importantly, these Treg inhibited antigen-specific T-cell activation in vitro and inhibited colitis due to antigen-specific pathogenic T cells in vivo.

Design, synthesis, and testing of difluoroboron-derivatized curcumins as near-infrared probes for in vivo detection of amyloid-beta deposits

Amyloid-beta (Abeta) deposits have been identified as key players in the progression of Alzheimer's disease (AD). Recent evidence indicates that the deposits probably precede and induce the neuronal atrophy. Therefore, methods that enable monitoring the pathology before clinical symptoms are observed would be beneficial for early AD detection. Here, we report the design, synthesis, and testing of a curcumin-derivatized near-infrared (NIR) probe, CRANAD-2. Upon interacting with Abeta aggregates, CRANAD-2 undergoes a range of changes, which include a 70-fold fluorescence intensity increase, a 90 nm blue shift (from 805 to 715 nm), and a large increase in quantum yield. Moreover, this probe also shows a high affinity for Abeta aggregates (K(d) = 38.0 nM), a reasonable log P value (log P = 3), considerable stability in serum, and a weak interaction with albumin. After intravenous injection of this probe, 19-month-old Tg2576 mice exhibited significantly higher relative signal than that of the control mice over the same period of time. In summary, CRANAD-2 meets all the requirements for a NIR contrast agent for the detection of Abeta plaques both in vitro and in vivo. Our data point toward the feasibility of monitoring the progress of the disease by NIR imaging with CRANAD-2. In addition, we believe that our probe could be potentially used as a tool for drug screening.

Curcumin-the paradigm of a multi-target natural compound with applications in cancer prevention and treatment

As cancer is a multifactor disease, it may require treatment with compounds able to target multiple intracellular components. We summarize here how curcumin is able to modulate many components of intracellular signaling pathways implicated in inflammation, cell proliferation and invasion and to induce genetic modulations eventually leading to tumor cell death. Clinical applications of this natural compound were initially limited by its low solubility and bioavailability in both plasma and tissues but combination with adjuvant and delivery vehicles was reported to largely improve bio-availability of curcumin. Moreover, curcumin was reported to act in synergism with several natural compounds or synthetic agents commonly used in chemotherapy. Based on this, curcumin could thus be considered as a good candidate for cancer prevention and treatment when used alone or in combination with other conventional treatments.

Structure-activity relationship of C5-curcuminoids and synthesis of their molecular probes thereof

A series of novel analogues of 1,5-bis(4-hydroxy-3-methoxyphenyl)-penta-(1E,4E)-1,4-dien-3-one (C(5)-curcumin), which is a natural analogue of curcumin isolated from the rhizomes of Curcuma domestica Val. (Zingiberacea), were synthesized and evaluated for their cytotoxicities against human colon cancer cell line HCT-116 to conclude the SAR of C(5)-curcuminoids for further development of their use in cancer chemotherapy: (1) Bis(arylmethylidene)acetone serves as a promising skeleton for eliciting cytotoxicity. (2) The 3-oxo-1,4-pentadiene structure is essential for eliciting cytotoxicity. (3) As for the extent of the aromatic substituents, hexasubstituted compounds exhibit strong activities, in which 3,4,5-hexasubstitution results in the highest potency. (5) The symmetry between two aryl rings is not an essential requirement for bis(arylmethylidene)acetones to elicit cytotoxicity. (6) para-Positions allows the installation of additional functional groups for use as molecular probes. By taking advantage of the SAR diagram, we have elaborated several advanced derivatives having GI(50) of single-digit micromolar potencies that will function as molecular probes to target and/or report key biomolecules interacting with curcumin and C(5)-curcumin.

Overexpression of the ATP binding cassette gene ABCA1 determines resistance to Curcumin in M14 melanoma cells

Background

Curcumin induces apoptosis in many cancer cells and it reduces xenograft growth and the formation of lung metastases in nude mice. Moreover, the plant derived polyphenol has been reported to be able to overcome drug resistance to classical chemotherapy. These features render the drug a promising candidate for tumor therapy especially for cancers known for their high rates concerning therapy resistance like melanoma.

Results

We show here that the melanoma cell line M14 is resistant to Curcumin induced apoptosis, which correlates with the absence of any effect on NFκB signaling. We show that CXCL1 a chemokine that is down regulated in breast cancer cells by Curcumin in an NFκB dependant manner is expressed at variable levels in human melanomas. Yet in M14 cells, CXCL1 expression did not change upon Curcumin treatment. Following the hypothesis that Curcumin is rapidly removed from the resistant cells, we analyzed expression of known multi drug resistance genes and cellular transporters in M14 melanoma cells and in the Curcumin sensitive breast cancer cell line MDA-MB-231. ATP-binding cassette transporter ABCA1, a gene involved in the cellular lipid removal pathway is over-expressed in resistant M14 melanoma as compared to the sensitive MDA-MB-231 breast cancer cells. Gene silencing of ABCA1 by siRNA sensitizes M14 cells to the apoptotic effect of Curcumin most likely as a result of reduced basal levels of active NFκB. Moreover, ABCA1 silencing alone also induces apoptosis and reduces p65 expression.

Conclusion

Resistance to Curcumin thus follows classical pathways and ABCA1 expression should be considered as response marker.

Redox-directed cancer therapeutics: molecular mechanisms and opportunities

Redox dysregulation originating from metabolic alterations and dependence on mitogenic and survival signaling through reactive oxygen species represents a specific vulnerability of malignant cells that can be selectively targeted by redox chemotherapeutics. This review will present an update on drug discovery, target identification, and mechanisms of action of experimental redox chemotherapeutics with a focus on pro- and antioxidant redox modulators now in advanced phases of preclinal and clinical development. Recent research indicates that numerous oncogenes and tumor suppressor genes exert their functions in part through redox mechanisms amenable to pharmacological intervention by redox chemotherapeutics. The pleiotropic action of many redox chemotherapeutics that involves simultaneous modulation of multiple redox sensitive targets can overcome cancer cell drug resistance originating from redundancy of oncogenic signaling and rapid mutation.Moreover, some redox chemotherapeutics may function according to the concept of synthetic lethality (i.e., drug cytotoxicity is confined to cancer cells that display loss of function mutations in tumor suppressor genes or upregulation of oncogene expression). The impressive number of ongoing clinical trials that examine therapeutic performance of novel redox drugs in cancer patients demonstrates that redox chemotherapy has made the crucial transition from bench to bedside.

Curcumin: a potential radio-enhancer in head and neck cancer

OBJECTIVES/HYPOTHESIS

To investigate whether curcumin enhances the cytotoxic effect of radiotherapy in head and neck squamous cell carcinoma (HNSCC).

METHODS

HNSCC cell lines SCC-1, SCC-9, KB, as well as A431 cell line were treated with curcumin, irradiation, or their combination. Cell viability was evaluated by XTT assay. Cyclooxygenase-2 (COX-2), epithelial growth factor receptor (EGFR), and p-Erk1/2 were measured by Western blot analysis. CD-1 athymic nude mice with orthotopic implanted SCC-1 cells, were treated with control diet, curcumin containing diet, local single-dose radiation, or combination.

RESULTS

Curcumin (IC50 range, 15-22 microM) and radiation inhibited cell viability in all cell lines were tested. The combination of curcumin and radiation resulted in additive effect. Curcumin decreased COX-2 expression and inhibited phosphorylation of EGFR in SCC-1 cells. In tumor-bearing mice the combination regimen showed a decrease in both tumor weight (25%, P = .09) and tumor size (15%, P = .23) compared to the nontreated mice.

CONCLUSIONS

: Curcumin inhibited HNSCC cell growth and augmented the effect of radiation in vitro and in vivo. A possible mechanism is inhibition of COX-2 expression and EGFR phosphorylation.

Curcumin modulates the radiosensitivity of colorectal cancer cells by suppressing constitutive and inducible NF-kappaB activity

PURPOSE

Radiation therapy is an integral part of the preoperative treatment of rectal cancers. However, only a minority of patients achieve a complete pathologic response to therapy because of resistance of these tumors to radiation therapy. This resistance may be mediated by constitutively active pro-survival signaling pathways or by inducible/acquired mechanisms in response to radiation therapy. Simultaneous inhibition of these pathways can sensitize these tumors to radiation therapy.

METHODS AND MATERIALS

Human colorectal cancer cells were exposed to clinically relevant doses of gamma rays, and the mechanism of their radioresistance was investigated. We characterized the transcription factor nuclear factor-kappaB (NF-kappaB) activation as a mechanism of inducible radioresistance in colorectal cancer and used curcumin, the active ingredient in the yellow spice turmeric, to overcome this resistance.

RESULTS

Curcumin inhibited the proliferation and the post-irradiation clonogenic survival of multiple colorectal cancer cell lines. Radiation stimulated NF-kappaB activity in a dose- and time-dependent manner, whereas curcumin suppressed this radiation-induced NF-kappaB activation via inhibition of radiation-induced phosphorylation and degradation of inhibitor of kappaB alpha, inhibition of inhibitor of kappaB kinase activity, and inhibition of Akt phosphorylation. Curcumin also suppressed NF-kappaB-regulated gene products (Bcl-2, Bcl-x(L), inhibitor of apoptosis protein-2, cyclooxygenase-2, and cyclin D1).

CONCLUSIONS

Our results suggest that transient inducible NF-kappaB activation provides a prosurvival response to radiation that may account for development of radioresistance. Curcumin blocks this signaling pathway and potentiates the antitumor effects of radiation therapy.

Curcumin induces proapoptotic effects against human melanoma cells and modulates the cellular response to immunotherapeutic cytokines

Curcumin has potential as a chemopreventative and chemotherapeutic agent, but its interactions with clinically relevant cytokines are poorly characterized. Because cytokine immunotherapy is a mainstay of treatment for malignant melanoma, we hypothesized that curcumin could modulate the cellular responsiveness to interferons and interleukins. As a single agent, curcumin induced a dose-dependent increase in apoptosis of human melanoma cell lines, which was most prominent at doses >10 micromol/L. Immunoblot analysis confirmed that curcumin induced apoptosis and revealed caspase-3 processing, poly ADP ribose polymerase cleavage, reduced Bcl-2, and decreased basal phosphorylated signal transducers and activators of transcription 3 (STAT3). Despite its proapoptotic effects, curcumin pretreatment of human melanoma cell lines inhibited the phosphorylation of STAT1 protein and downstream gene transcription following IFN-alpha and IFN-gamma as determined by immunoblot analysis and real time PCR, respectively. Pretreatment of peripheral blood mononuclear cells from healthy donors with curcumin also inhibited the ability of IFN-alpha, IFN-gamma, and interleukin-2 to phosphorylate STAT proteins critical for their antitumor activity (STAT1 and STAT5, respectively) and their respective downstream gene expression as measured by real time PCR. Finally, stimulation of natural killer (NK) cells with curcumin reduced the level of interleukin-12-induced IFN-gamma secretion, and production of granzyme b or IFN-gamma upon coculture with A375 melanoma cells or NK-sensitive K562 cells as targets. These data show that although curcumin can induce apoptosis of melanoma cells, it can also adversely affect the responsiveness of immune effector cells to clinically relevant cytokines that possess antitumor properties.

Histone acetyltransferase inhibitors and preclinical studies

BACKGROUND

Drugs able to regulate the histone modifier enzymes are very promising tools for the treatment of several diseases, such as cancer. Histone acetyltransferase (HAT) inhibitors are compounds able to inhibit the catalytic activity of HATs reported to be active in cancer, or in several other diseases, such as Alzheimer (AD), diabetes and hyperlipidaemia.

OBJECTIVES

Here we review the status and the rationale for the use of HAT inhibitors in the treatment of various diseases.

METHODS

Patents have been found on the espacenet database; the clinical trials have been reported as in the clinicaltrial.gov website.

RESULTS AND CONCLUSION

Despite the fact that other drugs able to regulate the histone modifier enzymes (such as histone deacetylase inhibitors) have been already approved for the treatment of cancer, HAT inhibitors seem promising for the treatment of human diseases such as AD and diabetes, although side effects and toxicity need to be investigated.

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.

Encapsulation and sustained release of curcumin using superparamagnetic silica reservoirs

For controlled release and targeted delivery of curcumin in an aqueous medium a method of encapsulating curcumin and magnetic nanoparticles inside porous silica matrix has been developed. Curcumin and superparamagnetic nanoparticles are loaded inside porous silica in a single process. The graphic shows the TEM image of microtomed sample of Fe(3)O(4) particles surrounded by a silica matrix.

Evidence of gamma-tocotrienol as an apoptosis-inducing, invasion-suppressing, and chemotherapy drug-sensitizing agent in human melanoma cells

To date, the most effective cure for metastatic melanoma remains the surgical resection of the primary tumor. Recently, tocotrienol-rich-fraction has shown antiproliferative effect on cancer cells. To elucidate this anticancer property in malignant melanoma, this study aimed, first, to identify the most potent isomer for eliminating melanoma cells and second to decipher the molecular pathway responsible for its activity. Results showed that the inhibitory effect of gamma-tocotrienol was most potent, which resulted in induction of apoptosis as evidenced by activation of procaspases and the accumulation of sub-G1 cell population. Examination of the prosurvival genes revealed that the gamma-tocotrienol-induced cell death was associated with suppression of NF-kappaB, EGF-R, and Id family proteins. Meanwhile, gamma-tocotrienol treatment also resulted in induction of JNK signaling pathway, and inhibition of JNK activity by selective inhibitor was able to partially block the effect of gamma-tocotrienol. Interestingly, gamma-tocotrienol treatment led to suppression of mesenchymal markers and the restoration of E-cadherin and gamma-catenin expression, which was associated with suppression of cell invasion capability. Furthermore, synergistic effect was observed when cells were cotreated with gamma-tocotrienol and chemotherapy drugs. Together, our results demonstrated for the first time the anti-invasion and chemonsensitization effect of gamma-tocotrienol against human malignant melanoma cells.

Chemopreventive action of Lygodium flexuosum extract in human hepatoma PLC/PRF/5 and Hep 3B cells

ETHNOPHARMACOLOGICAL RELEVANCE

Lygodium flexuosum (Lygodiaceae), a medicinal fern used in Indian traditional medicine against liver disorders.

AIM OF THE STUDY

The rationale of the study was to examine whether the n-hexane extract from plant Lygodium flexuosum affects apoptosis on human hepatoma PLC/PRF/5 and Hep 3B cells.

MATERIALS AND METHODS

Chemopreventive activity of the Lygodium flexuosum extract was determined by MTT assay, annexin-V FITC binding to phosphatidyl serine and cleavage of PARP. Subdiploid condition of cells treated with Lygodium flexuosum was analyzed by flow cytometry. Further, used transiently transfected NF-kappaB reporter in PLC/PRF/5 cells to evaluate the inhibitive effect of Lygodium flexuosum extract.

RESULTS

Lygodium flexuosum extract inhibited the cell viability and induced apoptosis in hepatoma cells in a concentration dependent manner as evidenced by apoptotic changes such as flipping of phosphatidyl serine, cleavage of PARP. Cell cycle analysis showed the subG1 apoptotic population in cells treated with higher concentrations of the extract. When activated with exogenous TNF-alpha in transfected hepatoma cells it was observed that NF-kappaB dependent gene expression was inhibited by treatment with Lygodium flexuosum extract in PLC/PRF/5 cells dose-dependently.

CONCLUSIONS

This investigation suggests that the Lygodium flexuosum extract has antiproliferative and apoptotic activity in both cancer cells and has inhibitive role in TNF-alpha induced NF-kappaB activation in PLC/PRF/5 cells confirms the potential of the extract as a chemopreventive agent.

Turmeric and green tea: a recipe for the treatment of B-chronic lymphocytic leukemia

Two naturally occurring compounds, curcumin, the active ingredient in the spice turmeric, and the green tea extract epigallocatechin-3-gallate, have marked effects on the apoptotic machinery in chronic lymphocytic leukemia. These results provide a preclinical foundation for future clinical use of these compounds in this disease.

Multi-targeted therapy by curcumin: how spicy is it?

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.

Immunomodulatory effects of curcumin in allergy

Recent years have witnessed a global increase in allergy and asthma, particularly in developed countries. Attempts to develop effective control measures for allergy and asthma resulted in the exploration of alternate medicines including herbal remedies traditionally used in old world countries. Turmeric is known for its multiple health restoring properties, and has been used in treating several diseases including several respiratory disorders. Turmeric is a common spice used in the culinary preparations in South and East Asian countries. The active component of turmeric is curcumin, a polyphenolic phytochemical, with anti-inflammatory, antiamyloid, antiseptic, antitumor, and antioxidative properties. Curcumin was reported to have antiallergic properties with inhibitory effect on histamine release from mast cells. The effectiveness of curcumin in allergy and asthma has been further investigated using a murine model of allergy. The results indicate a marked inhibition of allergic response in animals treated with curcumin suggesting a major role for curcumin in reducing the allergic response. The present review focuses on the results of research aimed to understand the immunomodulation induced by curcumin and its associated roles in the amelioration of allergy. These findings needed further evaluation, extrapolation, and confirmation before using curcumin for controlling allergy and asthma in humans.

The cinnamon-derived Michael acceptor cinnamic aldehyde impairs melanoma cell proliferation, invasiveness, and tumor growth

Redox dysregulation in cancer cells represents a chemical vulnerability that can be targeted by pro-oxidant redox intervention. Dietary constituents that contain an electrophilic Michael acceptor pharmacophore may therefore display promising chemopreventive and chemotherapeutic anti-cancer activity. Here, we demonstrate that the cinnamon-derived dietary Michael acceptor trans-cinnamic aldehyde (CA) impairs melanoma cell proliferation and tumor growth. Feasibility of therapeutic intervention using high doses of CA (120 mg/kg, po, daily, 10 days) was demonstrated in a human A375 melanoma SCID mouse xenograft model. Low-micromolar concentrations (IC(50)< 10 microM) of CA, but not closely related CA derivatives devoid of Michael acceptor activity, suppressed proliferation of human metastatic melanoma cell lines (A375, G361, LOX) with G1 cell-cycle arrest, elevated intracellular ROS, and impaired invasiveness. Expression array analysis revealed that CA induced an oxidative stress response in A375 cells, up-regulating heme oxygenase 1, sulfiredoxin 1 homolog, thioredoxin reductase 1, and other genes, including the cell-cycle regulator and stress-responsive tumor suppressor gene cyclin-dependent kinase inhibitor 1A, a key mediator of G1-phase arrest. CA, but not Michael-inactive derivatives, inhibited NF-kappaB transcriptional activity and TNFalpha-induced IL-8 production in A375 cells. These findings support a previously unrecognized role of CA as a dietary Michael acceptor with potential anti-cancer activity.

Synthesis and biological evaluation of curcuminoid pyrazoles as new therapeutic agents in inflammatory bowel disease: effect on matrix metalloproteinases

Seven N-unsubstituted curcuminoid pyrazoles have been synthesized from the corresponding beta-diketones (including curcumin). We evaluated the possibility of curcuminoid pyrazoles regulating the activity of matrix metalloproteinases (MMPs) by human intestinal epithelial cells in vitro. Zymographic analysis revealed that three compounds significantly down-regulated MMP-9 activity on inflammation-induced intestinal epithelial cells, making them original candidates for the treatment of inflammatory bowel disease (IBD).

Liposome-encapsulated curcumin suppresses growth of head and neck squamous cell carcinoma in vitro and in xenografts through the inhibition of nuclear factor kappaB by an AKT-independent pathway

PURPOSE

The purpose of this study was to determine whether a liposomal formulation of curcumin would suppress the growth of head and neck squamous cell carcinoma (HNSCC) cell lines CAL27 and UM-SCC1 in vitro and in vivo.

EXPERIMENTAL DESIGN

HNSCC cell lines were treated with liposomal curcumin at different doses and assayed for in vitro growth suppression using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. A reporter gene assay was done on cell lines to study the effect of liposomal curcumin on nuclear factor kappaB (NFkappaB) activation. Western blot analysis was done to determine the effect of curcumin on the expression of NFkappaB, phospho-IkappaBalpha, phospho-AKT (pAKT), phospho-S6 kinase, cyclin D1, cyclooxygenase-2, matrix metalloproteinase-9, Bcl-2, Bcl-xL, Mcl-1L, and Mcl-1S. Xenograft mouse tumors were grown and treated with intravenous liposomal curcumin. After 5 weeks, tumors were harvested and weighed. Immunohistochemistry and Western blot analyses were used to study the effect of liposomal curcumin on the expression of NFkappaB and pAKT.

RESULTS

The addition of liposomal curcumin resulted in a dose-dependent growth suppression of both cell lines. Liposomal curcumin treatment suppressed the activation of NFkappaB without affecting the expression of pAKT or its downstream target phospho-S6 kinase. Expression of cyclin D1, cyclooxygenase-2, matrix metalloproteinase-9, Bcl-2, Bcl-xL, Mcl-1L, and Mcl-1S were reduced, indicating the effect of curcumin on the NFkappaB pathway. Nude mice xenograft tumors were suppressed after 3.5 weeks of treatment with i.v. liposomal curcumin, and there was no demonstrable toxicity of liposomal curcumin upon autopsy. Immunohistochemistry and Western blot analysis on xenograft tumors showed the inhibition of NFkappaB without affecting the expression of pAKT.

CONCLUSIONS

Liposomal curcumin suppresses HNSCC growth in vitro and in vivo. The results suggest that liposomal curcumin is a viable nontoxic therapeutic agent for HNSCC that may work via an AKT-independent pathway.

Anticancer and carcinogenic properties of curcumin: considerations for its clinical development as a cancer chemopreventive and chemotherapeutic agent

A growing body of research suggests that curcumin, the major active constituent of the dietary spice turmeric, has potential for the prevention and therapy of cancer. Preclinical data have shown that curcumin can both inhibit the formation of tumors in animal models of carcinogenesis and act on a variety of molecular targets involved in cancer development. In vitro studies have demonstrated that curcumin is an efficient inducer of apoptosis and some degree of selectivity for cancer cells has been observed. Clinical trials have revealed that curcumin is well tolerated and may produce antitumor effects in people with precancerous lesions or who are at a high risk for developing cancer. This seems to indicate that curcumin is a pharmacologically safe agent that may be used in cancer chemoprevention and therapy. Both in vitro and in vivo studies have shown, however, that curcumin may produce toxic and carcinogenic effects under specific conditions. Curcumin may also alter the effectiveness of radiotherapy and chemotherapy. This review article analyzes the in vitro and in vivo cancer-related activities of curcumin and discusses that they are linked to its known antioxidant and pro-oxidant properties. Several considerations that may help develop curcumin as an anticancer agent are also discussed.

Micelles of poly(ethylene oxide)-b-poly(epsilon-caprolactone) as vehicles for the solubilization, stabilization, and controlled delivery of curcumin

Curcumin is recognized as a potential chemotherapeutic agent against a variety of tumors. However, the clinical application of curcumin is hindered due to its poor water solubility and fast degradation. The objective of this study was to investigate amphiphilic block copolymer micelles of poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-PCL) as vehicles for the solubilization, stabilization, and controlled delivery of curcumin. Curcumin-loaded PEO-PCL micelles were prepared by a cosolvent evaporation technique. PEO-PCL micelles were able to solubilize curcumin effectively, protect the encapsulated curcumin from hydrolytical degradation in physiological matrix, and control the release of curcumin over a few days. The characteristics of resultant micelles were found to depend on the polymerization degrees of epsilon-caprolactone. Among different PEO-PCL micelles, PEO(5000)-PCL(24500) was the most efficient in solubilizing curcumin while PEO(5000)-PCL(13000) was the best carrier in reducing its release rate. PEO-PCL micelle-encapsulated curcumin retained its cytotoxicity in B16-F10, a mouse melanoma cell line, and SP-53, Mino, and JeKo-1 human mantle cell lymphoma cell lines. These results demonstrated the potential of PEO-PCL micelles as an injectable formulation for efficient solubilization, stabilization, and controlled delivery of curcumin.

Modulation of anti-apoptotic and survival pathways by curcumin as a strategy to induce apoptosis in cancer cells

Apoptosis is a highly regulated mechanism by which cells undergo cell death in an active way. As one of the most challenging tasks concerning cancer is to induce apoptosis in malignant cells, researchers increasingly focus on natural products to modulate apoptotic signaling pathways. Curcumin, a natural compound isolated from the plant Curcuma longa, has chemopreventive properties, which are mainly due to its ability to arrest cell cycle and to induce apoptosis. This article reviews the main effects of curcumin on the different apoptotic signaling pathways involved in curcumin-induced apoptosis of cancer cells, including the intrinsic and extrinsic apoptosis pathways, the NF-kappaB-mediated pathway as well as the PI3K/Akt signaling pathway. This review also focuses on the sensitization of cells to TRAIL-induced apoptosis after curcumin treatment and shows that curcumin enhances the capacity to induce cell death of different chemotherapeutical drugs.

Curcumin (diferuloylmethane) inhibits cell proliferation, induces apoptosis, and decreases hormone levels and secretion in pituitary tumor cells

Prolactinomas are the most prevalent functional pituitary adenomas. Dopamine D2 receptor (D2R) agonists, such as bromocriptine are the first line of therapy; however, drug intolerance/resistance to D2R agonists exists. Apart from D2R agonists, there is no established medical therapy for prolactinomas; therefore, identifying novel therapeutics is warranted. Curcumin, a commonly used food additive in South Asian cooking, inhibits proliferation of several tumor cell lines; however, its effect on pituitary tumor cell proliferation has not been determined. Our objectives were to: 1) determine whether curcumin inhibits proliferation of pituitary tumor cell lines; 2) identify the signaling intermediaries that mediate the effect of curcumin; 3) examine whether curcumin inhibited pituitary hormone production and release; and 4) examine whether curcumin could enhance the growth-inhibitory effect of bromocriptine. Using rat lactotroph cell lines, GH3 and MMQ cells, we report that curcumin had a robust dose and time-dependent inhibitory effect on GH3 and MMQ cell proliferation. Inhibitory effects of curcumin persisted, even on removal of curcumin, and curcumin also blocked colony formation ability of pituitary tumor cells. The growth-inhibitory effect of curcumin was accompanied by decreased expression of cyclin D3 and ser 780 phosphorylation of retinoblastoma protein. In addition, curcumin also induced apoptosis in both GH3 and MMQ cells. Furthermore, curcumin suppresses intracellular levels and release of both prolactin and GH. Finally, we show that low concentrations of curcumin enhanced the growth-inhibitory effect of bromocriptine on MMQ cell proliferation. Taken together we demonstrate that curcumin inhibits pituitary tumor cell proliferation, induces apoptosis, and decreases hormone production and release, and thus, we propose developing curcumin as a novel therapeutic tool in the management of prolactinomas.

Potential therapeutic effects of curcumin, the anti-inflammatory agent, against neurodegenerative, cardiovascular, pulmonary, metabolic, autoimmune and neoplastic diseases

Although safe in most cases, ancient treatments are ignored because neither their active component nor their molecular targets are well defined. This is not the case, however, with curcumin, a yellow-pigment substance and component of turmeric (Curcuma longa), which was identified more than a century ago. For centuries it has been known that turmeric exhibits anti-inflammatory activity, but extensive research performed within the past two decades has shown that this activity of turmeric is due to curcumin (diferuloylmethane). This agent has been shown to regulate numerous transcription factors, cytokines, protein kinases, adhesion molecules, redox status and enzymes that have been linked to inflammation. The process of inflammation has been shown to play a major role in most chronic illnesses, including neurodegenerative, cardiovascular, pulmonary, metabolic, autoimmune and neoplastic diseases. In the current review, we provide evidence for the potential role of curcumin in the prevention and treatment of various proinflammatory chronic diseases. These features, combined with the pharmacological safety and negligible cost, render curcumin an attractive agent to explore further.

Curcumin (diferuloylmethane) alters the expression profiles of microRNAs in human pancreatic cancer cells

BACKGROUND

A major challenge in cancer chemotherapy has been developing safe and clinically efficacious chemotherapeutic agents. With its low toxicity profile, curcumin (diferuloylmethane), a naturally occurring flavinoid derived from the rhizome of Curcuma longa, has great promise. In vitro and in vivo preclinical studies have shown its inhibitory anticancer, antioxidant, anti-inflammatory, antiproliferative, and proapoptotic activities. The multiple mechanisms of the antitumor effect of curcumin putatively include down-regulating the expression of gene products such as nuclear factor-kappaB, growth suppression, inducing apoptosis, and modulating various signal transduction pathways and the expression of many oncogenes. The mechanisms underlying the antitumor activity of curcumin have not, however, been completely delineated.

METHODS

An oligonucleotide microarray chip was developed and used to profile microRNA (miRNA) expressions in pancreatic cells treated with curcumin. Transcripts with regulated expression patterns on the arrays were validated by real-time PCRs. Additionally, potential mRNA targets were analyzed bioinformatically and confirmed with flow cytometry experiments.

RESULTS

Curcumin alters miRNA expression in human pancreatic cells, up-regulating miRNA-22 and down-regulating miRNA-199a*, as confirmed by TaqMan real-time PCR. Upregulation of miRNA-22 expression by curcumin or by transfection with miRNA-22 mimetics in the PxBC-3 pancreatic cancer cell line suppressed expression of its target genes SP1 transcription factor (SP1) and estrogen receptor 1 (ESR1), while inhibiting miRNA-22 with antisense enhanced SP1 and ESR1 expression.

CONCLUSIONS

These observations suggest that modulation of miRNA expression may be an important mechanism underlying the biological effects of curcumin.

Delayed activation of PKCdelta and NFkappaB and higher radioprotection in splenic lymphocytes by copper (II)-Curcumin (1:1) complex as compared to curcumin

A mononuclear 1:1 copper complex of curcumin had been found to be superior to curcumin in its anti-oxidant properties. This paper describes the radio-protective effects of the complex in splenic lymphocytes from swiss mice. The complex was found to be very effective in protecting the cells against radiation-induced suppression of glutathione peroxidase, catalase and superoxide dismutase (SOD) activities. Both curcumin and the complex protected radiation-induced protein carbonylation and lipid peroxidation in lymphocytes with the complex showing better protection than curcumin. It also showed better overall protection by decreasing the radiation-induced apoptosis. The kinetics of activation of PKCdelta and NFkappaB after irradiation in presence or absence of these compounds was looked at to identify the molecular mechanism involved. The modulation of irradiation-induced activation of PKCdelta and NFkappaB by curcumin and the complex was found different at later time periods although the initial response was similar. The early responses could be mere stress responses and the activation of crucial signaling factors at later time periods may be the determinants of the fate of the cell. In this study this delayed effect was observed in case of complex but not in case of curcumin. The delayed effect of the complex along with the fact that it is a better free radical scavenger must be the reason for its better efficacy. The complex was also found to be less cytotoxic then curcumin at similar concentration.

Cell cycle checkpoint models for cellular pharmacology of paclitaxel and platinum drugs

A pharmacokinetic-pharmacodynamic mathematical model is developed for cellular pharmacology of chemotherapeutic drugs for which the decisive step towards cell death occurs at a point in the cell cycle, presumably corresponding to a cell cycle checkpoint. For each cell, the model assumes a threshold level of some intracellular species at that checkpoint, beyond which the cell dies. The threshold level is assumed to have a log-normal distribution in the cell population. The kinetics of formation of the lethal intracellular species depends on the drug, and on the cellular pharmacokinetics and binding kinetics of the cell. Specific models are developed for paclitaxel and for platinum drugs (cisplatin, oxaliplatin and carboplatin). In the case of paclitaxel, two separate mechanisms of cell death necessitate a model that accounts for two checkpoints, with different intracellular species. The model was tested on a number of in vitro cytotoxicity data sets for these drugs, and found overall to give significantly better fits than previously proposed cellular pharmacodynamic models. It provides an explanation for the asymptotic convergence of dose-response curves as exposure time becomes long.

Curcumin treatment enhances islet recovery by induction of heat shock response proteins, Hsp70 and heme oxygenase-1, during cryopreservation

Limited recovery of islets post-cryopreservation influences graft survival and transplantation efficiency during diabetes treatment. As curcumin, a potent antioxidant/radical scavenging compound, protects islets against beta cell toxins, we hypothesized that inclusion of curcumin during cryopreservation or during post-thaw culture or both may rescue islets from cryoinjury. To test the effect of curcumin inclusion on islet recovery murine islets were isolated by the collagenase digestion, cultured for 48 h, cryopreserved using dimethylsulphoxide as cryoprotectant -- with or without curcumin (10 microM) -- and then slow cooled to -40 degrees C before immersing them in liquid nitrogen for 7 days. Following rapid thawing with sucrose gradient and 24 h post-thaw culture -- in presence or absence of curcumin (10 microM) -- islet viability and functionality were determined. Islet recovery in curcumin treated groups was significantly higher than in groups where islets were cryopreserved without curcumin. Islets cryopreserved with curcumin also showed more intact islets as well as better morphology as compared to islets cryopreserved without curcumin. Curcumin treated islets also showed significant inhibition of ROS generation as compared to islets cryopreserved without curcumin. Glucose responsiveness and insulin secretion in islets cryopreserved with curcumin was equal to that of the freshly isolated islets as against islets cryopreserved without curcumin. Elevated level of Hsp 70 and HO-1 were observed in islets cryopreserved with curcumin and may contribute to curcumin-induced islet rescue. Hence, we conclude that inclusion of curcumin into cryopreservation medium inhibits ROS generation and corresponding islet damage and dysfunction.

Curcumin downregulates the constitutive activity of NF-κB and induces apoptosis in novel mouse melanoma cells

Melanoma, the most deadly form of skin cancer, is very aggressive and resistant to present therapies. The transcription factor nuclear factor-kappa B (NF-kappaB) has been reported to be constitutively active in many types of cancer. Constitutively active NF-kappaB seen in melanoma likely plays a central role in cell survival and growth. We have established and characterized novel cell lines from our murine melanoma model. Here we report the constitutive activity of NF-kappaB in these melanoma-derived cells, as shown by electrophoretic mobility shift assay and reporter assays. We hypothesized that agents that inhibit NF-kappaB may also inhibit cell proliferation and may induce apoptosis in such melanoma cells. Curcumin has been shown to inhibit NF-kappaB activity in several cell types. In our system, curcumin selectively inhibited growth of melanoma cells, but not normal melanocytes. Curcumin induced melanoma cells to undergo apoptosis, as shown by caspase-3 activation, inversion of membrane phosphatidyl serine, and increases in cells in the sub-G1 phase. A curcumin dose-dependent inhibition of NF-kappaB-driven reporter activity correlated with decreased levels of phospho-IkappaBalpha, and decreased expression of NF-kappaB-target genes COX-2 and cyclin D1. This study demonstrates that the use of cells from our model system can facilitate studies of signaling pathways in melanoma. We furthermore conclude that curcumin, a natural and safe compound, inhibits NF-kappaB activity and the expression of its downstream target genes, and also selectively induces apoptosis of melanoma cells but not normal melanocytes. These encouraging in-vitro results support further investigation of curcumin for treatment of melanoma in vivo.

Curcumin inhibits tumor growth and angiogenesis in ovarian carcinoma by targeting the nuclear factor-kappaB pathway

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.

CELL GROWTH REGULATION

Curcumin, the active ingredient of turmeric (Curcuma longa) used in culinary and medical practices in Asia, has immense potential for being used in cancer chemotherapy because of its control over the cell growth regulatory mechanisms. The present chapter throws light on the role of curcumin in modulating the various phases of the cell cycle and its apoptosis-inducing effects. This is followed by a discussion on the implications of these effects of curcumin for its use as a chemotherapeutic agent in cancer. Curcumin affects various cell cycle proteins and checkpoints involving downregulation of some of the cyclins and cyclin-dependent kinases, upregulation of cdk inhibitors, and inhibition of DNA synthesis. In addition, curcumin also exerts indirect control over cell division such as inhibition of telomerase activity. Remarkably, some studies point toward a selective growth-inhibitory effect of curcumin on transformed cell lines compared to nontransformed cell lines. Curcumin has also been demonstrated to have proapoptotic effects in several in vitro studies, mostly through the mitochondria-mediated pathway of apoptosis. Curcumin-mediated regulation of apoptosis involves caspases, Bcl2 family members, inhibitors of apoptosis proteins, and heat shock proteins. The accumulating data on the in vitro and in vivo actions of curcumin together with the ongoing human clinical trials will provide a better understanding of curcumin-mediated cell growth regulation, ultimately catering to the needs of human welfare.