Curcumin-Induced Cell Death in Two Leukemia Cell Lines: K562 and Jurkat

A renewed concept on the MAPK signaling pathway in cancers: Polyphenols as a choice of therapeutics

Abnormalities in the mitogen-activated protein kinase (MAPK) signaling pathway are a key contributor to the carcinogenesis process and have therefore been implicated in several aspects of tumorigenesis, including cell differentiation, proliferation, invasion, angiogenesis, apoptosis, and metastasis. This pathway offers multiple molecular targets that may be modulated for anticancer activity and is of great interest for several malignancies. Polyphenols from various dietary sources have been observed to interfere with certain aspects of this pathway and consequently play a substantial role in the development and progression of cancer by suppressing cell growth, inactivating carcinogens, blocking angiogenesis, causing cell death, and changing immunity. A good number of polyphenolic compounds have shown promising outcomes in numerous pieces of research and are currently being investigated clinically to treat cancer patients. The current study concentrates on the role of the MAPK pathway in the development and metastasis of cancer, with particular emphasis on dietary polyphenolic compounds that influence the different MAPK sub-pathways to obtain an anticancer effect. This study aims to convey an overview of the various aspects of the MAPK pathway in cancer development and invasion, as well as a review of the advances achieved in the development of polyphenols to modulate the MAPK signaling pathway for better treatment of cancer.

CD123-Targeted Nano-Curcumin Molecule Enhances Cytotoxic Efficacy in Leukemic Stem Cells

Acute myeloblastic leukemia (AML) is a disease with a high rate of relapse and drug resistance due to the remaining leukemic stem cells (LSCs). Therefore, LSCs are specific targets for the treatment of leukemia. CD123 is specifically expressed on LSCs and performs as a specific marker. Curcumin is the main active compound of a natural product with low toxicity for humans. It has been reported to inhibit leukemic cell growth. However, curcumin is practically insoluble in water and has low bioavailability. In this study, we aimed to formulate curcumin nanoparticles and conjugate with the anti-CD123 to overcome the low water solubility and improve the targeting of LSCs. The cytotoxicity of both curcumin-loaded PLGA/poloxamer nanoparticles (Cur-NPs) and anti-CD123-curcumin-loaded PLGA/poloxamer nanoparticles (anti-CD123-Cur-NPs) were examined in KG-1a cells. The results showed that Cur-NPs and Cur-NPs-CD123 exhibited cytotoxic effects on KG-1a cells with the IC₅₀ values of 74.20 ± 6.71 and 41.45 ± 5.49 µM, respectively. Moreover, anti-CD123-Cur-NPs induced higher apoptosis than Cur-NPs. The higher uptake of anti-CD123-Cur-NPs in KG-1a cells was confirmed by using flow cytometry. In conclusion, the anti-CD123-Cur-NPs formulation improved curcumin's bioavailability and specific targeting of LSCs, suggesting that it is a promising drug delivery system for improving the therapeutic efficacy against AML.

Phytochemical Screening and Antioxidant and Cytotoxic Effects of Acacia macrostachya

Acacia macrostachya is used in Burkina Faso folk medicine for the treatment of inflammation and cancer. The purpose of this study was to evaluate the antioxidant and cytotoxic effects of this plant. The cytotoxic effects of root (dichloromethane B1 and methanol B2) and stem (dichloromethane B3 and methanol B4) bark extracts of A. macrostachya were assessed on chronic K562 and acute U937 myeloid leukemia cancer cells using trypan blue, Hoechst, and MitoTracker Red staining methods. The antioxidant content of extracts was evaluated using DPPH (2,2-diphenyl-1-picryl-hydrazyl) and FRAP (ferric reducing antioxidant power) methods. The root bark extracts B1 and B2 of A. macrostachya demonstrated higher cytotoxicity with IC₅₀ values in a low µg/mL range on both U937 and K562 cells, while the stem bark B4 extract selectively affected U937 cells. Overall, healthy proliferating peripheral blood mononuclear cells (pPBMCs) were not or barely impacted in the range of concentrations cytotoxic to cancer cells. In addition, A. macrostachya exhibited significant antioxidant content with 646.06 and 428.08 µg ET/mg of extract for the B4 and B2 extracts, respectively. Phytochemical screening showed the presence of flavonoids, tannins, alkaloids, and terpenoids/steroids. The results of this study highlight the interest of A. macrostachya extracts for the isolation of anticancer molecules.

Anticancer potential of naturally occurring immunoepigenetic modulators: A promising avenue?

The immune system represents the major primary defense line against carcinogenesis and acts by identifying and eradicating nascent transformed cells. A growing body of evidence is indicating that aberrant epigenetic reprogramming plays a key role in tumor immune escape through: 1) impaired efficient recognition of neoplastic cells by the immune system, resulting from a downregulation or loss of the expression of tumor-associated antigens, human leukocyte antigens, antigen processing and presenting machinery, and costimulatory molecule genes; 2) aberrant expression of immune checkpoint proteins and their ligands; and 3) modification of cytokine profiles and tumor-associated immune cell populations toward an immunosuppressive state in the tumor microenvironment. Consistent with the inherent reversibility of epigenetic alterations, epigenetic drugs, including DNA methyltransferase and histone deacetylase inhibitors, have the unique potential to favorably modify the tumor microenvironment, restore tumor recognition and stimulate an antitumor immune response. The objective of this review is to highlight selected, naturally occurring epigenetic modulators, namely, butyrate, curcumin, (-)-epigallocatechin-3-gallate, resveratrol, romidepsin, and trichostatin A, with a special focus on their antitumor immune properties.

FLT3-specific curcumin micelles enhance activity of curcumin on FLT3-ITD overexpressing MV4-11 leukemic cells

Curcumin, a major active compound in the turmeric rhizome, has many biological properties, especially anti-leukemia activity. The overexpression of FMS-like tyrosine kinase 3 protein with internal tandem duplication (FLT3-ITD) mutation protein was related to the poor prognosis and disease progression of leukemia. In this study, the cytotoxicity and inhibitory effect of curcumin on cell cycle of FLT3-ITD overexpressing MV4-11 leukemic cells were evaluated. Moreover, curcumin polymeric micelles conjugated with FLT3-specific peptide (FLT3-Cur-micelles) were prepared using a film hydration method to increase curcumin solubility and the inhibitory effect on MV4-11 cells was evaluated. Cytotoxicity and cell cycle analysis were performed using an MTT assay and flow cytometry, respectively. Physical properties of FLT3-Cur-micelles, including particle size, size distribution, morphology, and entrapment efficiency (EE), were evaluated. Cellular uptake of the micelles on MV4-11 cells was determined by flow cytometry and fluorescence microscopy. FLT3-Cur-micelles were observed with size less than 50 nm and high EE of >75%. In addition, FLT3-Cur-micelles demonstrated excellent internalization and increased curcumin accumulation in leukemic cells when compared to free curcumin. Furthermore, FLT3-Cur-micelles exhibited a strong cytotoxic effect on MV4-11 cells with IC₅₀ value of 1.1 µM, whereas the blank micelles showed no effect. Furthermore, FLT3-Cur-micelles showed no significant effect on normal human PBMCs with IC₅₀ value >25 µM. In summary, FLT3-Cur-micelles are a promising nanocarrier system for enhancing anti-leukemic activity of curcumin and suitable for further preclinical studies.

Femtosecond laser pulse assisted photoporation for drug delivery in Chronic myelogenous leukemia cells

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder occurs in the pluripotent hematopoietic stem cell. Currently, first-generation tyrosine kinase inhibitor (TKI) imatinib is the mainstay for the treatment of CML. Second generation TKI's like ponatinib, dasatinib, nilotinib, and bafetinib were treated against resistant CML. However, several CML patients develop resistance towards all existing inhibitors. Curcumin (Curcuma longa) a plant-derived natural compound is an effective bioactive component against various cancers including CML. Many studies have shown that curcumin induces time- and dose-dependent apoptosis in CML cells by regulating various downstream molecular regulators. Despite curcumin's selective cytotoxicity towards cancer cells, it has very poor bioavailability both in in-vitro and in-vivo conditions. In this present study, we have used femtosecond laser (fs-laser) pulses to ablate the cell membrane and standardized the conditions required for creating a cell membrane pores with less lethality. Following fs-laser pulse irradiation, K562 cells were incubated along with curcumin 30 μM for 0 h, 6 h,12 h and 24 h. Interestingly irradiated cells have shown higher sensitivity towards curcumin than non-irradiated cells. Immunoblotting studies showed higher induction levels of cleaved caspase 3 and 9 in irradiated population than non-irradiated. In summary, the results prove that irradiation by fs-laser pulses enhanced the bioavailability of curcumin and shows caspase-mediated cell death in irradiated CML cells than other populations.

Curcumin differentially affects cell cycle and cell death in acute and chronic myeloid leukemia cells

Curcumin is a phytochemical with potent anti-neoplastic properties. The antitumoral effects of curcumin in cells derived from chronic or acute myeloid leukemia have been already described. However, a comparative study of the cytostatic and cytotoxic effects of curcumin on chronic and acute myeloid leukemia cells has not yet been performed. In the present study, the cellular effects of curcumin on cell lines derived from chronic or acute myeloid leukemia were examined. Dose and time-response assays were performed with curcumin on HL-60 and K562 cells. Cell viability was evaluated with trypan blue exclusion test and cell death by flow cytometry using a fluorescent molecular probe. A cell cycle profile was analyzed, and protein markers of cell cycle progression and cell death were investigated. In the present study, the K562 cells showed a higher sensitivity to the cytostatic and cytotoxic effects of curcumin compared with HL-60. In addition, curcumin induced G1 phase arrest in HL-60 cells and G2/M phase arrest in K562 cells. Furthermore, curcumin-related cell death in HL-60 was associated with the processed forms of caspases-9 and -3 proteins, whereas in K562 cells, both the processed and the unprocessed forms were present. Accordingly, activity of these caspases was significantly higher in HL-60 cells compared with that in K562. In conclusion, curcumin elicits different cellular mechanisms in chronic or acute myeloid leukemia cells and the powerful antitumoral effect was more potent in K562 compared with HL-60 cells.

Novel Curcumin Liposome Modified with Hyaluronan Targeting CD44 Plays an Anti-Leukemic Role in Acute Myeloid Leukemia in Vitro and in Vivo

Curcumin has been widely used as a food additive for centuries and has been recently explored for its anti-inflammatory and antitumor properties. Although curcumin is pharmacologically safe and efficacious to certain cancers, its role against acute myeloid leukemia (AML) still remains unclear, and it lacks clinical application due to low water solubility and low in vivo bioavailability. To address these issues, we developed a novel curcumin liposome modified with hyaluronan (HA-Cur-LPs) to specifically deliver curcumin to AML by targeting CD44 on AML cell surface. When compared with free curcumin and nontargeted liposome (Cur-LPs), the HA-Cur-LPs exhibited good stability, high affinity to CD44, increased cellular uptake, and more potent activity on inhibiting AML cell proliferation. The KG-1 cell implanted AML mice had significantly delayed, or even prevented, AML progression following treatment with 50 mg/kg of curcumin dose in the HA-Cur-LPs every 2 days for 2 weeks. Mechanistically, the anti-AML effects of HA-Cur-LPs were achieved by inhibiting Akt/ERK pathways and activating caspase-dependent apoptosis. Moreover, HA-Cur-LPs played a critical role in downregulation of DNMT1 expression in AML, leading to DNA hypomethylation and reactivation of tumor suppressor genes such as miR-223. The development and assessment of the HA-Cur-LPs in this study provide another potential choice for AML therapy, using HA-Cur-LPs as either a single treatment agent or in combination with other treatments.

Development and Characterization of FLT3-Specific Curcumin-Loaded Polymeric Micelles as a Drug Delivery System for Treating FLT3-Overexpressing Leukemic Cells

This study aimed at developing a curcumin (CM) nanoparticle targeted to Feline McDonough Sarcoma (FMS)-like tyrosine kinase 3 (FLT3) protein on the surface of leukemic cells and at evaluating their properties, specificity, cytotoxicity, and inhibitory effect on FLT3 protein level in FLT3-overexpressing leukemic cells, EoL-1, and MV-4-11 cells. FLT3-specific peptides were conjugated onto modified poloxamer 407 using the copper-catalyzed azide-alkyne cycloaddition reaction. The thin film hydration method was performed for FLT3-specific CM-loaded polymeric micelles (FLT3-CM-micelles) preparation. Flow cytometry and fluorescence microscopy were used to determine rate of cellular uptake. 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to test the cytotoxicity of the micelles on leukemic cells. FLT3-CM-micelles demonstrated a mean particle size less than 50 nm, high entrapment efficiency, and high rate of CM uptake by leukemic cells. The intracellular CM fluorescence is related to FLT3 protein levels on the leukemic cell surfaces. Moreover, FLT3-CM-micelles demonstrated an excellent cytotoxic effect and decreased FLT3 protein expression in the leukemic cells. The FLT3-CM-micelles could enhance both solubility and cytotoxicity of CM on FLT3-overexpressing leukemic cells. These promising nanoparticles may be used for enhancing antileukemic activity of CM and developed as a targeted drug delivery system in the future.

Non-canonical programmed cell death mechanisms triggered by natural compounds

Natural compounds are the fundament of pharmacological treatments and more than 50% of all anticancer drugs are of natural origins or at least derived from scaffolds present in Nature. Over the last 25 years, molecular mechanisms triggered by natural anticancer compounds were investigated. Emerging research showed that molecules of natural origins are useful for both preventive and therapeutic purposes by targeting essential hallmarks and enabling characteristics described by Hanahan and Weinberg. Moreover, natural compounds were able to change the differentiation status of selected cell types. One of the earliest response of cells treated by pharmacologically active compounds is the change of its morphology leading to ultra-structural perturbations: changes in membrane composition, cytoskeleton integrity, alterations of the endoplasmic reticulum, mitochondria and of the nucleus lead to formation of morphological alterations that are a characteristic of both compound and cancer type preceding cell death. Apoptosis and autophagy were traditionally considered as the most prominent cell death or cell death-related mechanisms. By now multiple other cell death modalities were described and most likely involved in response to chemotherapeutic treatment. It can be hypothesized that especially necrosis-related phenotypes triggered by various treatments or evolving from apoptotic or autophagic mechanisms, provide a more efficient therapeutic outcome depending on cancer type and genetic phenotype of the patient. In fact, the recent discovery of multiple regulated forms of necrosis and the initial elucidation of the corresponding cell signaling pathways appear nowadays as important tools to clarify the immunogenic potential of non-canonical forms of cell death induction.

Cationic triblock copolymer micelles enhance antioxidant activity, intracellular uptake and cytotoxicity of curcumin

The aim of the present study was to develop curcumin loaded cationic polymeric micelles and to evaluate their loading, preservation of curcumin antioxidant activity and intracellular uptake ability. The micelles were prepared from a triblock copolymer consisting of poly(ϵ-caprolactone) and very short poly(2-(dimethylamino) ethyl methacrylate) segments (PDMAEMA9-PCL70-PDMAEMA9). The micelles showed monomodal size distribution, mean diameter of 145 nm, positive charge (+72 mV), critical micellar concentration around 0.05 g/l and encapsulation efficiency of 87%. The ability of the micellar curcumin to scavenge the ABTS radical and hypochlorite ions was higher than that of the free curcumin. Confocal microscopy revealed that the uptake of curcumin by chronic myeloid leukemia derived K-562 cells and human multiple myeloma cells U-266 was more intensive when curcumin was loaded into the micelles. These results correlated with the higher cytotoxicity of the micellar curcumin compared to free curcumin. Intraperitoneal treatment of Wistar rats indicated that PDMAEMA-PCL-PDMAEMA copolymer, comprising very short cationic chains, did not change the levels of malondialdehyde and glutathione in livers indicating an absence of oxidative stress. Thus, PDMAEMA-PCL-PDMAEMA triblock micelles could be considered efficient and safe platform for curcumin delivery.

Celecoxib prevents curcumin-induced apoptosis in a hematopoietic cancer cell model

Molecules targeting pro-inflammatory pathways have demonstrated beneficial effects in cancer treatment. More recently, combination of natural and synthetic anti-inflammatory drugs was suggested as an appealing strategy to inhibit tumor growth. Herein, we show that curcumin, a polyphenol from Curcuma longa and celecoxib induce apoptosis in hematopoietic cancer cell lines (Hel, Jurkat, K562, Raji, and U937). Further investigations on the most sensitive cell line, U937, indicated that these effects were tightly associated with an accumulation of the cells in S and G2/M for curcumin and in G0/G1 phase of cell cycle for celecoxib, respectively. The effect of celecoxib on cell cycle is associated with an induction of p27 and the down-regulation of cyclin D1. However, in the case of combination experiments, the pretreatment of U937 cells with celecoxib at non-apoptogenic concentrations counteracted curcumin-induced apoptosis. We found that this effect correlated with the prevention of the accumulation in S and G2/M phase of cell cycle induced by curcumin. Similar results have been obtained when celecoxib and curcumin were co-administrated at the same time. Overall our data suggest that this natural and synthetic drug combination is detrimental for cell death induction.

Inhibitory effect of turmeric curcuminoids on FLT3 expression and cell cycle arrest in the FLT3-overexpressing EoL-1 leukemic cell line

Leukemia is a hematologic malignancy with a frequent incidence and high mortality rate. Previous studies have shown that the FLT3 gene is overexpressed in leukemic blast cells, especially in acute myeloid leukemia. In this study, a commercially available curcuminoid mixture (1), pure curcumin (2), pure demethoxycurcumin (3), and pure bisdemethoxycurcumin (4) were investigated for their inhibitory effects on cell growth, FLT3 expression, and cell cycle progression in an FLT3-overexpressing EoL-1 leukemic cell line using an MTT assay, Western blotting, and flow cytometry, respectively. The mixture (1) and compounds 2-4 demonstrated cytotoxic effects with IC50 values ranging from 6.5 to 22.5 μM. A significant decrease in FLT3 protein levels was found after curcuminoid treatment with IC20 doses, especially with mixture 1 and compound 2. In addition, mixture 1 and curcumin (2) showed activity on cell cycle arrest at the G0/G1 phase and decreased the FLT3 and STAT5A protein levels in a dose-dependent manner. Compound 2 demonstrated the greatest potential for inhibiting cell growth, cell cycle progression, and FLT3 expression in EoL-1 cells. This investigation has provided new findings regarding the effect of turmeric curcuminoids on FLT3 expression in leukemic cells.

Role of altholactone in inducing type II apoptosis signalling pathway and expression of cancer-related genes in cervical carcinoma HeLa cell line

Goniothalamus species (Annonaceae) is a shrub that grows in the rainforest of tropical Asia. Several compounds have been isolated and exhibit the potential use for cancer treatment. In this work, altholactone isolated from Goniothalamus macrophyllus was investigated for its cytotoxicity, apoptosis signalling and the expression of cancer-related genes in the cervical carcinoma HeLa cells. Cytotoxicity was evaluated by MTT assay. Apoptotic characteristics were evaluated by morphological studies. Caspase-3 activity was detected using a fluorogenic substrate. Cytochrome c release from mitochondria and protein Bid were determined by Western blotting and cancer-related genes expression by RT-PCR. The results demonstrated that altholactone was cytotoxic to HeLa (IC50  = 9.6 μg/mL), and apoptotic cell death was manifested by appearance of chromatin condensation and caspase-3 activation, which was inhibited by specific inhibitors of both caspase-8 and -9. Release into the cytosol of cytochrome and cleavage of Bid occurred. Altholactone also caused a decrease in bcl-2 and an increase in p53 expression. These unique properties of altholactone suggest a potential for cancer chemotherapy.

Curcumin-induced autophagy contributes to the decreased survival of oral cancer cells

Curcumin, a major active component of turmeric Curcuma longa, has been shown to have inhibitory effects on cancers. In vitro studies suggest that curcumin inhibits cancer cell growth by activating apoptosis, but the mechanism underlying the anticancer effects of curcumin is unclear. Recently, it has been suggested that autophagy may play an important role in cancer therapy. However, little data are available regarding the role of autophagy in oral cancers. In this study, we have shown that curcumin has anticancer activity against oral squamous cell carcinoma (OSCC). Induction of autophagy, marked by autophagic vacuoles formation, was detected by acridine orange staining and monodansylcadaverine (MDC) dye after exposure to curcumin. Conversion of LC3-I to LC3-II, a marker of active autophagosome formation, was also detectable by Western blot following curcumin treatment. We have also observed that curcumin induced reactive oxygen species (ROS) production and autophagic vacuoles formation by curcumin was almost completely blocked in the presence of N-acetylcystein (NAC), an antioxidant. Rescue experiments using an autophagy inhibitor suppressed curcumin-induced cell death in OSCC, confirming that autophagy acts as a pro-death signal. Furthermore, curcumin shows anticancer activity against OSCC via both autophagy and apoptosis. These findings suggest that curcumin may potentially contribute to oral cancer treatment and provide useful information for the development of a new therapeutic agent.

Identification of differentially expressed proteins in curcumin-treated prostate cancer cell lines

Due to high prevalence and slow progression of prostate cancer, primary prevention appears to be attractive strategy for its eradication. During the last decade, curcumin (diferuloylmethane), a natural compound from the root of turmeric (Curcuma longa), was described as a potent chemopreventive agent. Curcumin exhibits anti-inflammatory, anticarcinogenic, antiproliferative, antiangiogenic, and antioxidant properties in various cancer cell models. This study was designed to identify proteins involved in the anticancer activity of curcumin in androgen-dependent (22Rv1) and -independent (PC-3) human prostate cancer cell lines using two-dimensional difference in gel electrophoresis (2D-DIGE). Out of 425 differentially expressed spots, we describe here the MALDI-TOF-MS analysis of 192 spots of interest, selected by their expression profile. This approach allowed the identification of 60 differentially expressed proteins (32 in 22Rv1 cells and 47 in PC-3 cells). Nineteen proteins are regulated in both cell lines. Further bioinformatic analysis shows that proteins modulated by curcumin are implicated in protein folding (such as heat-shock protein PPP2R1A; RNA splicing proteins RBM17, DDX39; cell death proteins HMGB1 and NPM1; proteins involved in androgen receptor signaling, NPM1 and FKBP4/FKBP52), and that this compound could have an impact on miR-141, miR-152, and miR-183 expression. Taken together, these data support the hypothesis that curcumin is an interesting chemopreventive agent as it modulates the expression of proteins that potentially contribute to prostate carcinogenesis.

Epigenetics Offer New Horizons for Colorectal Cancer Prevention

In recent years, colorectal cancer (CRC) incidence has been increasing to become a major cause of morbidity and mortality worldwide from cancers, with high rates in westernized societies and increasing rates in developing countries. Epigenetic modifications including changes in DNA methylation, histone modifications, and non-coding RNAs play a critical role in carcinogenesis. Epidemiological data suggest that, in comparison to other cancers, these alterations are particularly common within the gastrointestinal tract. To explain these observations, environmental factors and especially diet were suggested to both prevent and induce CRC. Epigenetic alterations are, in contrast to genetic modifications, potentially reversible, making the use of dietary agents a promising approach in CRC for the development of chemopreventive strategies targeting epigenetic mechanisms. This review focuses on CRC-related epigenetic alterations as a rationale for various levels of prevention strategies and their potential modulation by natural dietary compounds.

Epigenetics Offer New Horizons for Colorectal Cancer Prevention

In recent years, colorectal cancer (CRC) incidence has been increasing to become a major cause of morbidity and mortality worldwide from cancers, with high rates in westernized societies and increasing rates in developing countries. Epigenetic modifications including changes in DNA methylation, histone modifications, and non-coding RNAs play a critical role in carcinogenesis. Epidemiological data suggest that, in comparison to other cancers, these alterations are particularly common within the gastrointestinal tract. To explain these observations, environmental factors and especially diet were suggested to both prevent and induce CRC. Epigenetic alterations are, in contrast to genetic modifications, potentially reversible, making the use of dietary agents a promising approach in CRC for the development of chemopreventive strategies targeting epigenetic mechanisms. This review focuses on CRC-related epigenetic alterations as a rationale for various levels of prevention strategies and their potential modulation by natural dietary compounds.

Potential of the dietary antioxidants resveratrol and curcumin in prevention and treatment of hematologic malignancies

Despite considerable improvements in the tolerance and efficacy of novel chemotherapeutic agents, the mortality of hematological malignancies is still high due to therapy relapse, which is associated with bad prognosis. Dietary polyphenolic compounds are of growing interest as an alternative approach, especially in cancer treatment, as they have been proven to be safe and display strong antioxidant properties. Here, we provide evidence that both resveratrol and curcumin possess huge potential for application as both chemopreventive agents and anticancer drugs and might represent promising candidates for future treatment of leukemia. Both polyphenols are currently being tested in clinical trials. We describe the underlying mechanisms, but also focus on possible limitations and how they might be overcome in future clinical use – either by chemically synthesized derivatives or special formulations that improve bioavailability and pharmacokinetics.

Gene expression profiling related to anti-inflammatory properties of curcumin in K562 leukemia cells

A strong relationship exists between inflammation and carcinogenesis. To bring insights into the anti-inflammatory mechanisms by which chemopreventive agents, such as curcumin, are able to counteract the action of inflammation mediators, such as tumor necrosis factor-alpha (TNF-alpha), we compared gene expression profiles in K562 cells treated with curcumin-TNF-alpha versus TNF-alpha alone. Microarray data analysis revealed that, among the 376 differentially expressed genes by curcumin treatment, genes belonging to the cell cycle and the Janus kinase-signal transducer and activator of transcription signaling pathways were downregulated. This study also indicated that the upregulation of the heat shock family genes is highly implicated in the anti-inflammatory effect of curcumin.

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.

Curcumin induces apoptosis through an ornithine decarboxylase-dependent pathway in human promyelocytic leukemia HL-60 cells

Curcumin, a well-known dietary pigment derived from the food flavoring turmeric (Curcuma longa) exhibits anti-proliferative, anti-inflammatory, and anti-oxidative activities. Recently, studies have shown that a chemopreventive effect of curcumin could be due to the hyperproduction of reactive oxygen species (ROS) inducing apoptosis in tumor cells. In our previous studies, ornithine decarboxylase (ODC) overexpression prevented tumor necrosis factor alpha (TNF-alpha)- and methotrexate-induced apoptosis via reduction of ROS. Furthermore, ODC is the rate-limiting enzyme in polyamine biosynthesis and a target for chemoprevention. In this study, we found that enzyme activity and protein expression of ODC were reduced during curcumin treatment. Overexpression of ODC in human promyelocytic leukemia HL-60 parental cells could reduce curcumin-induced apoptosis, which leads to loss of mitochondrial membrane potential (Deltapsi(m)), through reducing intracellular ROS. Moreover, ODC overexpression prevented cytochrome c release and the activation of caspase-9 and caspase-3 following curcumin treatment. These results demonstrate that curcumin-induced apoptosis occurs through a mechanism of down-regulating ODC and along a ROS-dependent mitochondria-mediated pathway.

CANCER CHEMOPREVENTIVE EFFECTS OF CURCUMIN

Chemoprevention, which is referred to as the use of nontoxic natural or synthetic chemicals to intervene in multistage carcinogenesis, has emerged as a promising and pragmatic medical approach to reduce the risk of cancer. Numerous components of edible plants, collectively termed "phytochemicals" have been reported to possess substantial chemopreventive properties. Curcumin, a yellow coloring ingredient derived from Curcuma longa L. (Zingiberaceae), is one of the most extensively investigated and well-defined chemopreventive phytochemicals. Curcumin has been shown to protect against skin, oral, intestinal, and colon carcinogenesis and also to suppress angiogenesis and metastasis in a variety animal tumor models. It also inhibits the proliferation of cancer cells by arresting them in the various phases of the cell cycle and by inducing apoptosis. Moreover, curcumin has a capability to inhibit carcinogen bioactivation via suppression of specific cytochrome P450 isozymes, as well as to induce the activity or expression of phase II carcinogen detoxifying enzymes. Well-designed intervention studies are necessary to assess the chemopreventive efficacy of curcumin in normal individuals as well as high-risk groups. Sufficient data from pharmacodynamic as well as mechanistic studies are necessary to advocate clinical evaluation of curcumin for its chemopreventive potential.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Cellular foundation of curcumin-induced apoptosis in follicular lymphoma cell lines

OBJECTIVE

Although responsive to first-line treatments, follicular lymphoma (FL) remains a fatal disease of increasing worldwide incidence. In efforts to find novel approaches to inhibit proliferation and induce apoptosis in FL cells, we examined the action of naturally occurring compound curcumin in the three recently established FL cell lines.

MATERIALS AND METHODS

Cytotoxic effects and determination of apoptotic attributes upon curcumin treatment were analyzed using growth inhibition, [(3)H]-thymidine, fluorescence microscopy, and flow cytometry assays, as well as Western blotting. Chemical inhibitor studies for the assessment of caspase and cathepsin contribution were applied. Expression of 10 members of the bcl-2 family proteins was evaluated by immunoblotting.

RESULTS

Curcumin inhibited proliferation and growth, and induced profound apoptosis associated with a shift in the balance of the bcl-2 family proteins, in all cell lines tested. Strikingly, we observed that curcumin-induced caspase-dependent apoptosis is also associated with lysosomal rupture (LMP). An increase in intracellular ROS generation appeared critical for curcumin-evoked LMP, loss of Deltapsi(m,) caspase activation, and cell death, as well as ascorbic acid-mediated enhancement of curcumin's action.

CONCLUSION

We have demonstrated for the first time that curcumin is an efficient inducer of apoptosis in FL cell lines, meriting its further evaluation in vivo.

Chemopreventive and therapeutic effects of curcumin

Chemoprevention is a promising anti-cancer approach with reduced secondary effects in comparison to classical chemotherapy. Curcumin, one of the most studied chemopreventive agents, is a natural compound extracted from Curcuma longa L. that allows suppression, retardation or inversion of carcinogenesis. Curcumin is also described as an anti-tumoral, anti-oxidant and anti-inflammatory agent capable of inducing apoptosis in numerous cellular systems. In this review, we describe both properties and mode of action of curcumin on carcinogenesis, gene expression mechanisms and drug metabolism.