Cellular signaling perturbation by natural products

Facile synthesis of indole heterocyclic compounds based micellar nano anti-cancer drugs

Facile synthesis of micellar “nano” indole heterocyclic anti-cancer compounds is described. The synthesized compounds (11–23) were characterized by UV-VIS, ¹H NMR, FT-IR and mass spectroscopy. The binding energies of DNA–compound adducts varied from −20.08 to −23.85 kJ mol⁻¹, and they were stabilized by hydrophobic interactions and H-bonding. The synthesized compounds enter into minor grooves of DNA during adduct formation. The DNA binding constant of compounds 11–23 was 1.00 to 2.00 × 10⁵ M⁻¹. The drug-loading efficiency and drug-loading content in their micellar forms were recorded. Compounds 11, 12, 14 and 19 at a micellar concentration of 670 μL mL⁻¹ displayed excellent anticancer activities against the HepG2/C3A line (25–50%). The potency of nano anticancer drugs was predicted by drug likeness using Lipinski's “rule of five”. Taken together, compounds 11–23 could be used to treat cancers.

Facile synthesis of micellar “nano” indole heterocyclic anti-cancer compounds is described.

1-Benzyl-indole-3-carbinol is a highly potent new small molecule inhibitor of Wnt/β-catenin signaling in melanoma cells that coordinately inhibits cell proliferation and disrupts expression of microphthalmia-associated transcription factor isoform-M

1-Benzyl-indole-3-carbinol (1-benzyl-I3C), a synthetic analogue of the crucifer-derived natural phytochemical I3C, displayed significantly wider sensitivity and anti-proliferative potency in melanoma cells than the natural compound. Unlike I3C, which targets mainly oncogenic BRAF-expressing cells, 1-benzyl-I3C effectively inhibited proliferation of melanoma cells with a more extensive range of mutational profiles, including those expressing wild-type BRAF. In both cultured melanoma cell lines and in vivo in melanoma cell-derived tumor xenografts, 1-benzyl-I3C disrupted canonical Wnt/β-catenin signaling that resulted in the downregulation of β-catenin protein levels with a concomitant increase in levels of the β-catenin destruction complex components such as glycogen synthase kinase-3β (GSK-3β) and Axin. Concurrent with the inhibition of Wnt/β-catenin signaling, 1-benzyl-I3C strongly downregulated expression of the melanoma master regulator, microphthalmia-associated transcription factor isoform-M (MITF-M) by inhibiting promoter activity through the consensus lymphoid enhancer factor-1 (LEF-1)/T-cell transcription factor (TCF) DNA-binding site. Chromatin immunoprecipitation revealed that 1-benzyl-I3C downregulated interactions of endogenous LEF-1 with the MITF-M promoter. 1-Benzyl-I3C ablated Wnt-activated LEF-1-dependent reporter gene activity in a TOP FLASH assay that was rescued by expression of a constitutively active form of the Wnt co-receptor low-density lipoprotein receptor-related protein (LRP6), indicating that 1-benzyl-I3C disrupts Wnt/β-catenin signaling at or upstream of LRP6. In oncogenic BRAF-expressing melanoma cells, combinations of 1-benzyl-I3C and Vemurafenib, a clinically employed BRAF inhibitor, showed strong anti-proliferative effects. Taken together, our observations demonstrate that 1-benzyl-I3C represents a new and highly potent indolecarbinol-based small molecule inhibitor of Wnt/β-catenin signaling that has intriguing translational potential, alone or in combination with other anti-cancer agents, to treat human melanoma.

Natural Bioactive Compounds: Alternative Approach to the Treatment of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most frequent, primary malignant brain tumor prevalent in humans. GBM characteristically exhibits aggressive cell proliferation and rapid invasion of normal brain tissue resulting in poor patient prognosis. The current standard of care of surgical resection followed by radiotherapy and chemotherapy with temozolomide is not very effective. The inefficacy of the chemotherapeutic agents may be attributed to the challenges in drug delivery to the tumor. Several epidemiological studies have demonstrated the chemopreventive role of natural, dietary compounds in the development and progression of cancer. Many of these studies have reported the potential of using natural compounds in combination with chemotherapy and radiotherapy as a novel approach for the effective treatment of cancer. In this paper, we review the role of several natural compounds individually and in combination with chemotherapeutic agents in the treatment of GBM. We also assess the potential of drug delivery approaches such as the Gliadel wafers and role of nanomaterial based drug delivery systems for the effective treatment of GBM.

Rumex dentatus Inhibits Cell Proliferation, Arrests Cell Cycle, and Induces Apoptosis in MDA-MB-231 Cells through Suppression of the NF-κB Pathway

Background:Rumex dentatus, commonly known as tooth docked, is widely used in traditional system of medicines. Although it is well reported for its biological activities and medicinal value, only few studies have been carried out to assess its anticancer potential.

Purpose: This study seeks to evaluate the anticancer activity of leaf extracts of R. dentatus against breast cancer MDA-MB-231 cell line, a triple negative human breast cancer cell line with invasive properties and to identify the molecular targets underlying its mechanism of action.

Methods: Cytotoxicity of plant extracts was determined against breast cancer cells, using the MTT assay. Flow cytometry was performed to analyze the changes in cell cycle and apoptotic effect, if any. Cells were also studied for their wound healing and invasive potential as well as for Western blotting of apoptotic genes and nuclear factor-kappaB (NF-κB) pathway.

Results: The results revealed that R. dentatus methanol (RM) and chloroform (RC) extracts of R. dentatus had the highest inhibition of cell proliferation in a concentration- and time-dependent manner. This inhibitory effect was found to be linked to arrest of cell cycle at the G0/G1 phase, along with induction of apoptosis and accumulation in the sub-G1 phase. Moreover, it was shown that both RM and RC inhibited the proliferation of the malignant cells and induced apoptosis by repressing the activation of NF-κB and its subsequent transcripts, Bcl-xl, Bcl-2, Cyclin D1, survivin, and XIAP. Apoptosis was also confirmed in the cells as suggested by caspase-3 detection. RM and RC also abrogated IκBa phosphorylation in the malignant cells as well as reduced the invasive and migratory capabilities of these cells.

Conclusion: Our findings suggest that the methanol and chloroform extracts of R. dentatus may have anti-cancer compounds that are potentially useful in the treatment of human breast cancer.

Molecular Mechanisms and Pathways as Targets for Cancer Prevention and Progression with Dietary Compounds

A unique feature of bioactive food ingredients is their broad antioxidant function. Antioxidants having a wide spectrum of chemical structure and activity beyond basic nutrition; display different health benefits by the prevention and progression of chronic diseases. Functional food components are capable of enhancing the natural antioxidant defense system by scavenging reactive oxygen and nitrogen species, protecting and repairing DNA damage, as well as modulating the signal transduction pathways and gene expression. Major pathways affected by bioactive food ingredients include the pro-inflammatory pathways regulated by nuclear factor kappa B (NF-κB), as well as those associated with cytokines and chemokines. The present review summarizes the importance of plant bioactives and their roles in the regulation of inflammatory pathways. Bioactives influence several physiological processes such as gene expression, cell cycle regulation, cell proliferation, cell migration, etc., resulting in cancer prevention. Cancer initiation is associated with changes in metabolic pathways such as glucose metabolism, and the effect of bioactives in normalizing this process has been provided. Initiation and progression of inflammatory bowel diseases (IBD) which increase the chances of developing of colorectal cancers can be downregulated by plant bioactives. Several aspects of the potential roles of microRNAs and epigenetic modifications in the development of cancers have also been presented.

The therapeutic potential of resveratrol: a review of clinical trials

Resveratrol is a nutraceutical with several therapeutic effects. It has been shown to mimic effects of caloric restriction, exert anti-inflammatory and anti-oxidative effects, and affect the initiation and progression of many diseases through several mechanisms. While there is a wealth of in vitro and in vivo evidence that resveratrol could be a promising therapeutic agent, clinical trials must confirm its potential. In this work, we reviewed the current clinical data available regarding the pharmacological action of resveratrol. Most of the clinical trials of resveratrol have focused on cancer, neurological disorders, cardiovascular diseases, diabetes, non-alcoholic fatty liver disease (NAFLD), and obesity. We found that for neurological disorders, cardiovascular diseases, and diabetes, the current clinical trials show that resveratrol was well tolerated and beneficially influenced disease biomarkers. However resveratrol had ambiguous and sometimes even detrimental effects in certain types of cancers and in NAFLD. In most of the clinical trials, the major obstacle presented was resveratrol’s poor bioavailability. Thus, this work provides useful considerations for the planning and design of future pre-clinical and clinical research on resveratrol.

WITHDRAWN: The anti-cancer properties in parallel with toxic effects of indole-3-carbinol derivatives

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Two likely targets for the anti-cancer effect of indole derivatives from cruciferous vegetables: PI3K/Akt/mTOR signalling pathway and the aryl hydrocarbon receptor

Diets containing high quantities of plant foods are linked with a decreased likelihood of incidence of cancer. Several common plant-based dietary components exert effects on DNA methylation levels, and can positively influence genome stability and the transcription of tumor suppressors and oncogenes. Indole-3-carbinol (I3C) is a substance present in vegetables of the Brassicaeae family, especially broccoli, white cabbage, Brussels sprouts and cauliflower. The in vivo biological effects of I3C are ascribed to a series of oligomeric products (including 3,3'-diindolylmethane), developed under acidic conditions. I3C is one of the many natural products and bioactive compounds found in foods which have recently received much attention for its potential effects in cancer prevention and treatment. In vitro studies report that I3C suppresses the proliferation of different tumor cells, including those isolated from breast, prostate, endometrium, and colon cancers. I3C resulted to be a potent in vivo chemopreventive agent for certain hormone-dependent cancers, including breast and cervical cancer. However, the mechanisms underlying these effects are not well defined. In this review, we have analysed recent literature on the use of indole derivatives against various forms of cancer, and have identified the main signalling pathways involved in their anti-cancer effect as PI3K/Akt/mTOR and the aryl hydrocarbon receptor.

Fisetin-induced apoptosis of human oral cancer SCC-4 cells through reactive oxygen species production, endoplasmic reticulum stress, caspase-, and mitochondria-dependent signaling pathways

Oral cancer is one of the cancer-related diseases in human populations and its incidence rates are rising worldwide. Fisetin, a flavonoid from natural products, has been shown to exhibit anticancer activities in many human cancer cell lines but the molecular mechanism of fisetin-induced apoptosis in human oral cancer cells is still unclear; thus, in this study, we investigated fisetin-induced cell death and associated signal pathways on human oral cancer SCC-4 cells in vitro. We examined cell morphological changes, total viable cells, and cell cycle distribution by phase contrast microscopy and flow cytometry assays. Reactive oxygen species (ROS), Ca²⁺ , mitochondria membrane potential (ΔΨ_m ), and caspase-8, -9, and -3 activities were also measured by flow cytometer. Results indicate that fisetin induced cell death through the cell morphological changes, caused G2/M phase arrest, induction of apoptosis, promoted ROS and Ca²⁺ production, and decreased the level of ΔΨ_m and increased caspase-3, -8, and -9 activities in SCC-4 cells. DAPI staining and DNA gel electrophoresis were also used to confirm fisetin-induced cell apoptosis in SCC-4 cells. Western blotting also found out that Fisetin increased the proapoptotic proteins such as Bax and Bid and decreased the antiapoptotic proteins such as Bcl-2. Furthermore, results also showed that Fisetin increased the cytochrome c, AIF, and Endo G release from mitochondria in SCC-4 cells. We also used ATF-6α, ATF-6β, GADD153, and GRP78 which indicated that fisetin induced cell death through ER stress. Based on those observations, we suggest that fisetin induced cell apoptosis through ER stress, mitochondria-, and caspase-dependent pathways.

Mannich Curcuminoids as Potent Anticancer Agents

A series of novel curcuminoids were synthesised for the first time via a Mannich-3CR/organocatalysed Claisen-Schmidt condensation sequence. Structure-activity relationship (SAR) studies were performed by applying viability assays and holographic microscopic imaging to these curcumin analogues for anti-proliferative activity against A549 and H1975 lung adenocarcinoma cells. The TNFα-induced NF-κB inhibition and autophagy induction effects correlated strongly with the cytotoxic potential of the analogues. Significant inhibition of tumour growth was observed when the most potent analogue 44 was added in liposomes at one-sixth of the maximally tolerated dose in the A549 xenograft model. The novel spectrum of activity of these Mannich curcuminoids warrants further preclinical investigations.

Naturally occurring compounds acting as potent anti-metastatic agents and their suppressing effects on Hedgehog and WNT/β-catenin signalling pathways

Despite numerous remarkable achievements in the field of anti-cancer therapy, tumour relapse and metastasis still remain major obstacles in improvement of overall cancer survival, which may be at least partially owing to epithelial-mesenchymal transition (EMT). Multiple signalling pathways have been identified in EMT; however, it appears that the role of the Hedgehog and WNT/β-catenin pathways are more prominent than others. These are well-known preserved intracellular regulatory pathways of different cellular functions including proliferation, survival, adhesion and differentiation. Over the last few decades, several naturally occurring compounds have been identified to significantly obstruct several intermediates in Hedgehog and WNT/β-catenin signalling, eventually resulting in suppression of signal transduction. This article highlights the current state of knowledge associated with Hedgehog and WNT/β-catenin, their involvement in metastasis through EMT processes and introduction of the most potent naturally occurring agents with capability of suppressing them, eventually overcoming tumour relapse, invasion and metastasis.

Involvement of PKCα and ERK1/2 signaling pathways in EGCG's protection against stress-induced neural injuries in Wistar rats

Stress-induced neural injuries are closely linked to the pathogenesis of various neuropsychiatric disorders and psychosomatic diseases. We and others have previously demonstrated certain protective effects of epigallocatechin-3-gallate (EGCG) in stress-induced cerebral impairments, but the underlying protective mechanisms still remain poorly elucidated. Here we provide evidence to support the possible involvement of PKCα and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways in EGCG-mediated protection against restraint stress-induced neural injuries in rats. In both open-field and step-through behavioral tests, the restraint stress-induced neuronal impairments were significantly ameliorated by administration of EGCG or green tea polyphenols (GTPs), which was associated with a partial restoration of normal plasma glucocorticoid, dopamine and serotonin levels. Furthermore, the stress-induced decrease of PKCα and ERK1/2 expression and phosphorylation was significantly attenuated by EGCG and to a less extent by GTP administration. Additionally, EGCG supplementation restored the production of adenosine triphosphate (ATP) and the expression of a key regulator of cellular energy metabolism, the peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α), in stressed animals. In conclusion, PKCα and ERK1/2 signaling pathways as well as PGC-1α-mediated ATP production might be involved in EGCG-mediated protection against stress-induced neural injuries.

Indole-3-carbinol (I3C) analogues are potent small molecule inhibitors of NEDD4-1 ubiquitin ligase activity that disrupt proliferation of human melanoma cells

The HECT domain-containing E3 ubiquitin ligase NEDD4-1 (Neural precursor cell Expressed Developmentally Down regulated gene 4-1) is frequently overexpressed in human cancers and displays oncogenic-like properties through the ubiquitin-dependent regulation of multiple protein substrates. However, little is known about small molecule enzymatic inhibitors of HECT domain-containing ubiquitin ligases. We now demonstrate that indole-3-carbinol (I3C), a natural anti-cancer phytochemical derived from cruciferous vegetables such as cabbage and broccoli, represents a new chemical scaffold of small molecule enzymatic inhibitors of NEDD4-1. Using in vitro ubiquitination assays, I3C, its stable synthetic derivative 1-benzyl-I3C and five novel synthetic analogues were shown to directly inhibit NEDD4-1 ubiquitination activity. Compared to I3C, which has an IC50 of 284μM, 1-benzyl-I3C was a significantly more potent NEDD4-1 enzymatic inhibitor with an IC50 of 12.3μM. Compounds 2242 and 2243, the two indolecarbinol analogues with added methyl groups that results in a more nucleophilic benzene ring π system, further enhanced potency with IC50s of 2.71μM and 7.59μM, respectively. Protein thermal shift assays that assess small ligand binding, in combination with in silico binding simulations with the crystallographic structure of NEDD4-1, showed that each of the indolecarbinol compounds bind to the purified catalytic HECT domain of NEDD4-1. The indolecarbinol compounds inhibited human melanoma cell proliferation in a manner that generally correlated with their effectiveness as NEDD4-1 enzymatic inhibitors. Taken together, we propose that I3C analogues represent a novel set of anti-cancer compounds for treatment of human melanomas and other cancers that express indolecarbinol-sensitive target enzymes.

Suppression of β-catenin Signaling Pathway in Human Prostate Cancer PC3 Cells by Delphinidin

Delphinidin possesses strong anti-oxidant, anti-inflammatory, and anti-cancer properties. Suppression of the Wnt/β-catenin signaling pathway is a potential strategy for chemoprevention and therapy. As aberrant activation of the β-catenin signaling pathway contributes to prostate cancer progression, we evaluated the effect of delphinidin on this pathway in human PC3 prostate cancer cells. An MTT assay showed that treatment with delphinidin (15–180 μM, 72 hours) resulted in a dose-dependent growth inhibition of cells. Treatment with delphinidin increased the phosphorylation of serine or threonine residues on β-catenin and decreased the levels of cytoplasmic β-catenin. Moreover, treatment with delphinidin inhibited the nuclear translocation of β-catenin and the expression of β-catenin target genes such as cyclin D1, c-myc, Axin-2, and T cell factor-1. Delphinidin also induced the phosphorylation of glycogen synthase kinase 3β and the expression of adenomatous polyposis coli and Axin proteins. Our results indicate that inhibition of cell growth by delphinidin is mediated, at least in part, through modulation of the β-catenin signaling pathway. We suggest that delphinidin is a potent inhibitor of Wnt/β-catenin signaling in prostate cancer cells.

An Aqueous Extract of Tuberaria lignosa Inhibits Cell Growth, Alters the Cell Cycle Profile, and Induces Apoptosis of NCI-H460 Tumor Cells

Tuberaria lignosa (Sweet) Samp. is found in European regions, and has antioxidant properties due to its composition in ascorbic acid and phenolic compounds. Given its traditional use and antioxidant properties, the tumor cell growth inhibitory potential of aqueous extracts from T. lignosa (prepared by infusion and decoction) was investigated in three human tumor cell lines: MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), and HCT-15 (human colorectal adenocarcinoma). Both extracts inhibited the growth of these cell lines; the most potent one being the T. lignosa extract obtained by infusion in the NCI-H460 cells (GI₅₀ of approximately 50 μg/mL). Further assays were carried out with this extract in NCI-H460 cells. At 100 μg/mL or 150 μg/mL it caused an increase in the percentage of cells in the G0/G1 phase and a decrease of cells in S phase of the cell cycle. Additionally, these concentrations caused an increase in the percentage of apoptotic cells. In agreement, a decrease in total poly (ADP-ribose) polymerase (PARP) and pro-caspase 3 levels was found. In conclusion, the T. lignosa extract obtained by infusion was more potent in NCI-H460 cells, altering the cell cycle progression and inducing apoptosis. This work highlights the importance of T. lignosa as a source of bioactive compounds with tumor cell growth inhibitory potential.

Chemoprevention in gastrointestinal physiology and disease. Targeting the progression of cancer with natural products: a focus on gastrointestinal cancer

The last decade has witnessed remarkable progress in the utilization of natural products for the prevention and treatment of human cancer. Many agents now in the pipeline for clinical trial testing have evolved from our understanding of how human nutritional patterns account for widespread differences in cancer risk. In this review, we have focused on many of these promising agents arguing that they may provide a new strategy for cancer control: natural products once thought to be only preventive in their mode of action now are being explored for efficacy in tandem with cancer therapeutics. Natural products may reduce off-target toxicity of therapeutics while making cancers more amenable to therapy. On the horizon is the use of certain natural products, in their own right, as mitigants of late-stage cancer, a new frontier for small-molecule natural product drug discovery.

Cooperative antiproliferative signaling by aspirin and indole-3-carbinol targets microphthalmia-associated transcription factor gene expression and promoter activity in human melanoma cells

Antiproliferative signaling of combinations of the nonsteroidal anti-inflammatory drug acetylsalicylic acid (aspirin) and indole-3-carbinol (I3C), a natural indolecarbinol compound derived from cruciferous vegetables, was investigated in human melanoma cells. Melanoma cell lines with distinct mutational profiles were sensitive to different extents to the antiproliferative response of aspirin, with oncogenic BRAF-expressing G361 cells and wild-type BRAF-expressing SK-MEL-30 cells being the most responsive. I3C triggered a strong proliferative arrest of G361 melanoma cells and caused only a modest decrease in the proliferation of SK-MEL-30 cells. In both cell lines, combinations of aspirin and I3C cooperatively arrested cell proliferation and induced a G1 cell cycle arrest, and nearly ablated protein and transcript levels of the melanocyte master regulator microphthalmia-associated transcription factor isoform M (MITF-M). In melanoma cells transfected with a -333/+120-bp MITF-M promoter-luciferase reporter plasmid, treatment with aspirin and I3C cooperatively disrupted MITF-M promoter activity, which accounted for the loss of MITF-M gene products. Mutational analysis revealed that the aspirin required the LEF1 binding site, whereas I3C required the BRN2 binding site to mediate their combined and individual effects on MITF-M promoter activity. Consistent with LEF1 being a downstream effector of Wnt signaling, aspirin, but not I3C, downregulated protein levels of the Wnt co-receptor LDL receptor-related protein-6 and β-catenin and upregulated the β-catenin destruction complex component Axin. Taken together, our results demonstrate that aspirin-regulated Wnt signaling and I3C-targeted signaling pathways converge at distinct DNA elements in the MITF-M promoter to cooperatively disrupt MITF-M expression and melanoma cell proliferation.

Synergistic Effects Induced by Combined Treatments of Aqueous Extract of Propolis and Venom

Background and aims

Breast cancer is a heterogeneous disease and the leading cause of cancer mortality worldwide. Triple negative breast cancer (TNBC) is considered to be one of the most aggressive breast neoplasia due to failure of chemotherapy response. Thus, there is an urgent need of finding alternative therapies for TNBC. This study was designed to evaluate the synergistic effect induced by propolis and bee venom on luminal (MCF-7) and TNBC (Hs578T) cell lines.

Methods

In order to evaluate the synergistic effect of aqueous extract of propolis and bee venom, we treated in combination two breast cancer cell lines: MCF-7(luminal subtype) and Hs578T (TNBC subtype).

Results

Our results indicate that both cell lines exhibited similar sensitivity to the aqueous extract of propolis at a dilution of 0.072–0.09 mg/ml. The results concerning IC50 for bee venom on MCF-7 cells was 1 mg/ml, 20 times higher than 0.05 mg/ml in Hs578T cells. By combining the aqueous extract of propolis with bee venom, we obtained synergistic effects at a higher concentration, which was 5 and 2 times stronger than the two treatments alone.

Conclusion

Overall, the results from our study indicated that the combination of aqueous extract of propolis and bee venom treatments induced synergistic antiproliferative effects in a concentration-dependent manner in breast cancer cells. Thus we can hypothesize that the combination of honeybee propolis and venom might be involved in signaling pathways that could overcome cells resistance to therapy.

Icaritin suppresses multiple myeloma, by inhibiting IL-6/JAK2/STAT3

Icaritin is an active prenylflavonoid derived from Epimedium genus, a traditional Chinese medicine. Icaritin has a wide range of pharmacological and biological activities, including cardiovascular function improvement, hormone regulation and antitumor activity. Here, we investigated the effect of icaritin on multiple myeloma (MM) in vitro and in vivo. Icaritin inhibited cell growth of MM cell line and primary MM cells. In contrast, icaritin had low or no cytotoxic effect on normal hematopoiesis. We also demonstrated that in MM xenograft mouse models, icaritin suppressed tumor growth and decreased serum IL-6 and IgE levels, but did not show adverse reactions such as body weight loss. The anti-MM activity of icaritin was mainly mediated by inhibiting IL-6/JAK2/STAT3 signaling. We suggest that icaritin can be further tested in clinical trials in MM.

The Curcumin Analog C-150, Influencing NF-κB, UPR and Akt/Notch Pathways Has Potent Anticancer Activity In Vitro and In Vivo

C-150 a Mannich-type curcumin derivative, exhibited pronounced cytotoxic effects against eight glioma cell lines at micromolar concentrations. Inhibition of cell proliferation by C-150 was mediated by affecting multiple targets as confirmed at transcription and protein level. C-150 effectively reduced the transcription activation of NFkB, inhibited PKC-alpha which are constitutively over-expressed in glioblastoma. The effects of C-150 on the Akt/ Notch signaling were also demonstrated in a Drosophila tumorigenesis model. C-150 reduced the number of tumors in Drosophila with similar efficacy to mitoxantrone. In an in vivo orthotopic glioma model, C-150 significantly increased the median survival of treated nude rats compared to control animals. The multi-target action of C-150, and its preliminary in vivo efficacy would render this curcumin analogue as a potent clinical candidate against glioblastoma.

Citrus bergamia Juice Extract Attenuates β-Amyloid-Induced Pro-Inflammatory Activation of THP-1 Cells Through MAPK and AP-1 Pathways

Flavonoids have been shown to be effective in protecting against age-related cognitive and motor decline in both in vitro and in vivo models. Recently, a flavonoid-rich extract of Citrus bergamia juice (BJe) has been shown to display anti-oxidant and anti-inflammatory properties against LPS-induced activation of human THP-1 monocytes. In the light of these observations, we wondered whether BJe may be beneficial against neuroinflammatory processes, such as those observed in Alzheimer’s disease. To this aim we used THP-1 monocytes to investigate the mechanisms underlying the beneficial potential of BJe against amyloid-beta_1–42 (Aβ₁₋₄₂) -mediated inflammation. Exposure of THP-1 cells to Aβ₁₋₄₂ significantly induced the expression and secretion of IL-6 and IL-1β in THP-1 cells and increased the phosphorylation of ERK 1/2 as well as p46 and p54 members of JNK family. Moreover, Aβ₁₋₄₂ raises AP-1 DNA binding activity in THP-1-treated cells. Interestingly, all these effects were reduced in the presence of BJe. Our data indicate that BJe may effectively counteract the pro-inflammatory activation of monocytes/microglial cells exposed to amyloid fibrils, suggesting a promising role as a natural drug against neuroinflammatory processes.

Natural Agents Used in Chemoprevention of Aerodigestive and GI Cancers

Aerodigestive cancers are on an increasing level in both occurrence and mortality. A major cause in many of these cancers is disruption of the inflammatory pathway, leading to increased cell proliferation, and epigenetic silencing of normal regulatory genes. Here we review the research on several natural products: silibinin, silymarin, quercetin, neem & nimbolide, gingerol, epigallatecatechin-3- gallate, curcumin, genistein and resveratrol conducted on aerodigestive cancers. These types of cancers are primarily those from oral cavity, esophagus/windpipe, stomach, small and large intestine, colon/rectum and bile/pancreas tissues. We report on the utilization in vivo and in vitro systems to research these dose effects on the inflammatory and epigenetic pathway components within the aerodigestive cancer. To follow up on the basic research we will discuss remaining research questions and future directions involving these natural products as putative stand alone or in combination with clinical agents.

High glucose and hyperglycemic sera from type 2 diabetic patients impair DC differentiation by inducing ROS and activating Wnt/β-catenin and p38 MAPK

Type 2 is the type of diabetes with higher prevalence in contemporary time, representing about 90% of the global cases of diabetes. In the course of diabetes, several complications can occur, mostly due to hyperglycemia and increased reactive oxygen species (ROS) production. One of them is represented by an increased susceptibility to microbial infections and by a reduced capacity to clear them. Therefore, knowing the impact of hyperglycemia on immune system functionality is of utmost importance for the management of the disease. In this study, we show that medium containing high glucose reduced the in-vitro differentiation of monocytes into functional DCs and their activation mediated by PAMPs or DAMPs. Most importantly, the same effects were mediated by the hyperglycemic sera derived by type 2 diabetic patients, mimicking a more physiologic condition. DC dysfunction caused by hyperglycemia may be involved in the inefficient control of infections observed in diabetic patients, given the pivotal role of these cells in both the innate and adaptive immune response. Searching for the molecular mechanisms underlying DC dysfunction, we found that canonical Wnt/β-catenin and p38 MAPK pathways were activated in the DCs differentiated either in the presence of high glucose or of hyper-glycemic sera. Interestingly, the activation of these pathways and the DC immune dysfunction were partially counteracted by the anti-oxidant quercetin, a flavonoid already known to exert several beneficial effects in diabetes.

Indole-3-Carbinol and Its Role in Chronic Diseases

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. Initially, these compounds were classified as blocking agents that increase drug-metabolizing enzyme activity. Now it is widely accepted that I3C and DIM affect multiple signaling pathways and target molecules controlling cell division, apoptosis, or angiogenesis deregulated in cancer cells. Although most of the current data support the role of I3C and DIM in prevention of hormone-dependent cancers, it seems that their application in prevention of the other cancer as well as cardiovascular disease, obesity, and diabetes reduction is also possible. This chapter summarizes the current experimental data on the I3C and DIM activity and the results of clinical studies indicating their role in prevention of chronic diseases.

Chemoprevention of Breast Cancer by Dietary Polyphenols

The review will discuss in detail the effects of polyphenols on breast cancer, including both the advantages and disadvantages of the applications of these natural compounds. First, we focus on the characterization of the main classes of polyphenols and then on in vitro and in vivo experiments carried out in breast cancer models. Since the therapeutic effects of the administration of a single type of polyphenol might be limited because of the reduced bioavailability of these drugs, investigations on combination of several polyphenols or polyphenols with conventional therapy will also be discussed. In addition, we present recent data focusing on clinical trials with polyphenols and new approaches with nanoparticles in breast cancer. Besides the clinical and translational findings this review systematically summarizes our current knowledge about the molecular mechanisms of anti-cancer effects of polyphenols, which are related to apoptosis, cell cycle regulation, plasma membrane receptors, signaling pathways and epigenetic mechanisms. At the same time the effects of polyphenols on primary tumor, metastasis and angiogenesis in breast cancer are discussed. The increasing enthusiasm regarding the combination of polyphenols and conventional therapy in breast cancer might lead to additional efforts to motivate further research in this field.

Evasion of anti-growth signaling: A key step in tumorigenesis and potential target for treatment and prophylaxis by natural compounds

The evasion of anti-growth signaling is an important characteristic of cancer cells. In order to continue to proliferate, cancer cells must somehow uncouple themselves from the many signals that exist to slow down cell growth. Here, we define the anti-growth signaling process, and review several important pathways involved in growth signaling: p53, phosphatase and tensin homolog (PTEN), retinoblastoma protein (Rb), Hippo, growth differentiation factor 15 (GDF15), AT-rich interactive domain 1A (ARID1A), Notch, insulin-like growth factor (IGF), and Krüppel-like factor 5 (KLF5) pathways. Aberrations in these processes in cancer cells involve mutations and thus the suppression of genes that prevent growth, as well as mutation and activation of genes involved in driving cell growth. Using these pathways as examples, we prioritize molecular targets that might be leveraged to promote anti-growth signaling in cancer cells. Interestingly, naturally occurring phytochemicals found in human diets (either singly or as mixtures) may promote anti-growth signaling, and do so without the potentially adverse effects associated with synthetic chemicals. We review examples of naturally occurring phytochemicals that may be applied to prevent cancer by antagonizing growth signaling, and propose one phytochemical for each pathway. These are: epigallocatechin-3-gallate (EGCG) for the Rb pathway, luteolin for p53, curcumin for PTEN, porphyrins for Hippo, genistein for GDF15, resveratrol for ARID1A, withaferin A for Notch and diguelin for the IGF1-receptor pathway. The coordination of anti-growth signaling and natural compound studies will provide insight into the future application of these compounds in the clinical setting.

A multi-targeted approach to suppress tumor-promoting inflammation

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

Mitochondria: a new therapeutic target in chronic kidney disease

Cellular metabolic changes during chronic kidney disease (CKD) may induce higher production of oxygen radicals that play a significant role in the progression of renal damage and in the onset of important comorbidities. This condition seems to be in part related to dysfunctional mitochondria that cause an increased electron "leakage" from the respiratory chain during oxidative phosphorylation with a consequent generation of reactive oxygen species (ROS). ROS are highly active molecules that may oxidize proteins, lipids and nucleic acids with a consequent damage of cells and tissues. To mitigate this mitochondria-related functional impairment, a variety of agents (including endogenous and food derived antioxidants, natural plants extracts, mitochondria-targeted molecules) combined with conventional therapies could be employed. However, although the anti-oxidant properties of these substances are well known, their use in clinical practice has been only partially investigated. Additionally, for their correct utilization is extremely important to understand their effects, to identify the correct target of intervention and to minimize adverse effects. Therefore, in this manuscript, we reviewed the characteristics of the available mitochondria-targeted anti-oxidant compounds that could be employed routinely in our nephrology, internal medicine and renal transplant centers. Nevertheless, large clinical trials are needed to provide more definitive information about their use and to assess their overall efficacy or toxicity.

Natural Products That Target Cancer Stem Cells

The cancer stem cell model suggests that tumor initiation is governed by a small subset of distinct cells with stem-like character termed cancer stem cells (CSCs). CSCs possess properties of self-renewal and intrinsic survival mechanisms that contribute to resistance of tumors to most chemotherapeutic drugs. The failure to eradicate CSCs during the course of therapy is postulated to be the driving force for tumor recurrence and metastasis. Recent studies have focused on understanding the unique phenotypic properties of CSCs from various tumor types, as well as the signaling pathways that underlie self-renewal and drug resistance. Natural products (NPs) such as those derived from botanicals and food sources may modulate vital signaling pathways involved in the maintenance of CSC phenotype. The Wingless/Integrated (WNT), Hedgehog, Notch and PI3K/AKT/mTOR pathways have all been associated with quiescence and self-renewal of CSCs, as well as execution of CSC function including differentiation, multidrug resistance and metastasis. Recent studies evaluating NPs against CSC support the epidemiological evidence linking plant-based diets with reduced malignancy rates. This review covers the key aspects of NPs as modulators of CSC fate.

Polyphenol Compound as a Transcription Factor Inhibitor

A target-based approach has been used to develop novel drugs in many therapeutic fields. In the final stage of intracellular signaling, transcription factor–DNA interactions are central to most biological processes and therefore represent a large and important class of targets for human therapeutics. Thus, we focused on the idea that the disruption of protein dimers and cognate DNA complexes could impair the transcriptional activation and cell transformation regulated by these proteins. Historically, natural products have been regarded as providing the primary leading compounds capable of modulating protein–protein or protein-DNA interactions. Although their mechanism of action is not fully defined, polyphenols including flavonoids were found to act mostly as site-directed small molecule inhibitors on signaling. There are many reports in the literature of screening initiatives suggesting improved drugs that can modulate the transcription factor interactions responsible for disease. In this review, we focus on polyphenol compound inhibitors against dimeric forms of transcription factor components of intracellular signaling pathways (for instance, c-jun/c-fos (Activator Protein-1; AP-1), c-myc/max, Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and β-catenin/T cell factor (Tcf)).

Antitumor activity of melinjo (Gnetum gnemon L.) seed extract in human and murine tumor models in vitro and in a colon-26 tumor-bearing mouse model in vivo

Melinjo (Gnetum gnemon L.) seed extract (MSE) and its active ingredient gnetin C (GC), a resveratrol dimer, have been shown to possess a broad spectrum of pharmacological activities. In this study, we investigated the antitumor activity of MSE and GC using human and murine tumor cell culture models in vitro. The antitumor activity of GC was compared with trans-resveratrol (tRV), a stilbenoid polyphenol. Our results show that MSE and GC at clinically achievable concentrations significantly inhibited the proliferation of pancreatic, prostate, breast, and colon cancer cell types (P < 0.05), without affecting normal cells. Interestingly, GC exerts enhanced antitumor activity than that of tRV (P < 0.05). MSE and GC significantly induced apoptosis in all the cancer cells, indicating MSE and GC inhibit tumor cell growth by inducing apoptosis (P < 0.001). Our findings provide evidence that MSE might induce apoptosis in cancer cells via caspase-3/7-dependent and -independent mechanisms. However, GC might trigger both early and late stage apoptosis in cancer cells, at least in part by activating caspase 3/7-dependent mechanisms. Furthermore, the antitumor efficacy of MSE observed in vitro was also validated in a widely used colon-26 tumor-bearing mouse model. Oral administration of MSE at 50 and 100 mg/kg per day significantly inhibited tumor growth, intratumoral angiogenesis, and liver metastases in BALB/c mice bearing colon-26 tumors (P < 0.05). In conclusion, our findings provide evidence that MSE and GC have potent antitumor activity. Most importantly, we provide the first evidence that MSE inhibits tumor growth, intratumoral angiogenesis, and liver metastasis in a colon-26 tumor-bearing mice.

Epigenetic activities of flavonoids in the prevention and treatment of cancer

Aberrant epigenetic modifications are described in an increasing number of pathological conditions, including neurodegenerative diseases, cardiovascular diseases, diabetes mellitus type 2, obesity and cancer. The general reversibility of epigenetic changes makes them an attractive and promising target e.g. in the treatment of cancer. Thus, a growing number of epigenetically active compounds are currently tested in clinical trials for their therapeutic potential. Interestingly, many phytochemicals present in plant foods, particularly flavonoids, are suggested to be able to alter epigenetic cellular mechanisms. Flavonoids are natural phenol compounds that form a large group of secondary plant metabolites with interesting biological activities. They can be categorized into six major subclasses, which display diverse properties affecting the two best characterized epigenetic mechanisms: modulation of the DNA methylation status and histone acetylation. High dietary flavonoid intake has strongly been suggested to reduce the risk of numerous cancer entities in a large body of epidemiological studies. Established health-promoting effects of diets rich in fruit and vegetables are faced by efforts to use purified flavonoids as supplements or pharmaceuticals, whereupon data on the latter applications remain controversial. The purpose of this review is to give an overview of current research on flavonoids to further elucidate their potential in cancer prevention and therapy, thereby focusing on their distinct epigenetic activities.

Dietary phytochemicals alter epigenetic events and signaling pathways for inhibition of metastasis cascade: phytoblockers of metastasis cascade

Cancer metastasis is a multistep process in which a cancer cell spreads from the site of the primary lesion, passes through the circulatory system, and establishes a secondary tumor at a new nonadjacent organ or part. Inhibition of cancer progression by dietary phytochemicals (DPs) offers significant promise for reducing the incidence and mortality of cancer. Consumption of DPs in the diet has been linked to a decrease in the rate of metastatic cancer in a number of preclinical animal models and human epidemiological studies. DPs have been reported to modulate the numerous biological events including epigenetic events (noncoding micro-RNAs, histone modification, and DNA methylation) and multiple signaling transduction pathways (Wnt/β-catenin, Notch, Sonic hedgehog, COX-2, EGFR, MAPK-ERK, JAK-STAT, Akt/PI3K/mTOR, NF-κB, AP-1, etc.), which can play a key role in regulation of metastasis cascade. Extensive studies have also been performed to determine the molecular mechanisms underlying antimetastatic activity of DPs, with results indicating that these DPs have significant inhibitory activity at nearly every step of the metastatic cascade. DPs have anticancer effects by inducing apoptosis and by inhibiting cell growth, migration, invasion, and angiogenesis. Growing evidence has also shown that these natural agents potentiate the efficacy of chemotherapy and radiotherapy through the regulation of multiple signaling pathways. In this review, we discuss the variety of molecular mechanisms by which DPs regulate metastatic cascade and highlight the potentials of these DPs as promising therapeutic inhibitors of cancer.

The role of targeting kinase activity by natural products in cancer chemoprevention and chemotherapy (Review)

The WHO clearly identifies tumors as a curable or a chronic disease. The use of natural agents in cancer prevention and therapy is currently playing an important role. Our laboratory has been investigating various natural phenolic compounds, including grifolin, neoalbaconol and epigallocatechin-3-gallate (EGCG). In the present review, we focus on the anticancer activities and the molecular mechanisms of these compounds. Grifolin, a secondary metabolite isolated from the mushroom Albatrellus confluens, has been shown to inhibit cell growth and induce cell cycle arrest in multiple cancer cell lines by targeting extracellular signal-regulated kinase 1 or by upregulating death-associated protein kinase 1 (DAPK1) via p53. We also demonstrated that neoalbaconol, a novel small-molecular compound with a drimane-type sesquiterpenoid structure obtained from Albatrellus confluens, regulates cell metabolism by targeting 3-phosphoinositide-dependent protein kinase 1 (PDK1) and inhibits cancer cell growth. EGCG, a well known catechin found in tea, has gained much attention for its anticancer effects. Previously, we found that it regulates EBV lytic infection through the phosphoinositide-3 kinase/Akt (PI3K/Akt) and mitogen-activated protein kinase (MAPK) pathways in EBV-positive cancer cells. Therefore, these natural agents could be used as potential leading compounds in the prevention of tumor progression and/or EBV-related cancer.

Soy and breast cancer: focus on angiogenesis

Epidemiological studies have revealed that high consumption of soy products is associated with low incidences of hormone-dependent cancers, including breast and prostate cancer. Soybeans contain large amounts of isoflavones, such as the genistein and daidzain. Previously, it has been demonstrated that genistein, one of the predominant soy isoflavones, can inhibit several steps involved in carcinogenesis. It is suggested that genistein possesses pleiotropic molecular mechanisms of action including inhibition of tyrosine kinases, DNA topoisomerase II, 5α-reductase, galectin-induced G2/M arrest, protein histidine kinase, and cyclin-dependent kinases, modulation of different signaling pathways associated with the growth of cancer cells (e.g., NF-κB, Akt, MAPK), etc. Moreover, genistein is also a potent inhibitor of angiogenesis. Uncontrolled angiogenesis is considered as a key step in cancer growth, invasion, and metastasis. Genistein was found to inhibit angiogenesis through regulation of multiple pathways, such as regulation of VEGF, MMPs, EGFR expressions and NF-κB, PI3-K/Akt, ERK1/2 signaling pathways, thereby causing strong antiangiogenic effects. This review focuses on the antiangiogenic properties of soy isoflavonoids and examines their possible underlying mechanisms.

Heteronemin, a Spongean Sesterterpene, Induces Cell Apoptosis and Autophagy in Human Renal Carcinoma Cells

Heteronemin is a bioactive marine sesterterpene isolated from the sponge Hyrtios sp. Previous reports have shown that heteronemin possesses anticancer activity. Here, heteronemin displayed cytotoxic effects against three human cancer cell lines (A549, ACHN, and A498) and exhibited potent activity in A498 human renal carcinoma cells, with an IC₅₀ value of 1.57 μM by MTT assay and a GI₅₀ value of 0.77 μM by SRB assay. Heteronemin initiates apoptotic cell death by downregulating Bcl-2 and Bcl-xL and upregulating Bax, leading to the disruption of the mitochondrial membrane potential and the release of cytochrome c from the mitochondria. These effects were associated with the activation of caspase-3/caspase-8/caspase-9, followed by PARP cleavage. Furthermore, heteronemin inhibited the phosphorylation of AKT signaling pathway and ERK and activated p38 and JNK. The specific inhibition of the p38 pathway by SB203580 or p38 siRNA treatment reversed the heteronemin-induced cytotoxicity and apoptotic signaling. Heteronemin also induced autophagy in A498 cells, and treatment with chloroquine (autophagy inhibitor) or SP600125 (JNK inhibitor) inhibited autophagy and increased heteronemin-induced cytotoxicity and apoptotic signaling. Taken together, this study proposes a novel treatment paradigm in which the combination of heteronemin and autophagy inhibitors leads to enhanced RCC cell apoptosis.

Novel Pactamycin Analogs Induce p53 Dependent Cell-Cycle Arrest at S-Phase in Human Head and Neck Squamous Cell Carcinoma (HNSCC) Cells

Pactamycin, although putatively touted as a potent antitumor agent, has never been used as an anticancer drug due to its high cytotoxicity. In this study, we characterized the effects of two novel biosynthetically engineered analogs of pactamycin, de-6MSA-7-demethyl-7-deoxypactamycin (TM-025) and 7-demethyl-7-deoxypactamycin (TM-026), in head and neck squamous cell carcinoma (HNSCC) cell lines SCC25 and SCC104. Both TM-025 and TM-026 exert growth inhibitory effects on HNSCC cells by inhibiting cell proliferation. Interestingly, unlike their parent compound pactamycin, the analogs do not inhibit synthesis of nascent protein in a cell-based assay. Furthermore, they do not induce apoptosis or autophagy in a dose- or a time-dependent manner, but induce mild senescence in the tested cell lines. Cell cycle analysis demonstrated that both analogs significantly induce cell cycle arrest of the HNSCC cells at S-phase resulting in reduced accumulation of G₂/M-phase cells. The pactamycin analogs induce expression of cell cycle regulatory proteins including master regulator p53, its downstream target p21^Cip1/WAF1, p27^kip21, p19, cyclin E, total and phospho Cdc2 (Tyr15) and Cdc25C. Besides, the analogs mildly reduce cyclin D1 expression without affecting expression of cyclin B, Cdk2 and Cdk4. Specific inhibition of p53 by pifithrin-α reduces the percentage of cells accumulated in S-phase, suggesting contribution of p53 to S-phase increase. Altogether, our results demonstrate that Pactamycin analogs TM-025 and TM-026 induce senescence and inhibit proliferation of HNSCC cells via accumulation in S-phase through possible contribution of p53. The two PCT analogs can be widely used as research tools for cell cycle inhibition studies in proliferating cancer cells with specific mechanisms of action.

The good and bad of antioxidant foods: An immunological perspective

Maintenance of redox homeostasis plays a central role in health and disease prevention, and antioxidant foods are thought to exert protective effects by counteracting oxidative stress. The term "dietary antioxidant" implies a classical reducing or radical-scavenging capacity, but more data on the in vivo bioactivity of such compounds are needed. Indeed, several dietary antioxidants activate signaling cascades that lead to effects that extend beyond radical scavenging, such as the induction of endogenous cytoprotective mechanisms and detoxification. Currently, the overall uptake of antioxidants with diet exceeds actual needs, as food additives that include vitamins, colorants, flavoring agents, and preservatives are often also relatively strong antioxidants. Chronic antioxidative stress favors adverse effects, such as the suppression of T helper (Th) type 1 immune responses and consequent activation of Th2 reactions that support the development of asthma, allergies, and obesity. In this context, we discuss the immunoregulatory pathway of tryptophan breakdown by enzyme indoleamine 2,3-dioxygenase (IDO), which represents a central regulatory hub for immune, metabolic, and neuroendocrine processes. Activation of IDO-mediated tryptophan metabolism is strongly redox-sensitive and is therefore susceptible to modulation by dietary components, phytochemicals, preservatives, and drugs.

The increasing roles of epigenetics in breast cancer: Implications for pathogenicity, biomarkers, prevention and treatment

Nowadays, the mechanisms governing the occurrence of cancer are thought to be the consequence not only of genetic defects but also of epigenetic modifications. Therefore, epigenetic has become a very attractive and increasingly investigated field of research in order to find new ways of prevention and treatment of neoplasia, and this is particularly the case for breast cancer (BC). Thus, this review will first develop the main known epigenetic modifications that can occur in cancer and then expose the future role that control of epigenetic modifications might play in prevention, prognostication, follow-up and treatment of BC. Indeed, epigenetic biomarkers found in peripheral blood might become new tools to detect BC, to define its prognostic and to predict its outcome, whereas epi-drugs might have an increasing potential of development in the next future. However, if DNA methyltransferase inhibitors and histone desacetylase inhibitors have shown encouraging results in BC, their action remains nonspecific. Thus, additional clinical studies are needed to evaluate more precisely the effects of these molecules, even if they have provided encouraging results in cotreatment and combined therapies. This review will also deal with the potential of RNA interference (RNAi) as epi-drugs. Finally, we will focus on the potential prevention of BC through epigenetic based on diet and we will particularly develop the possible place of isothiocyanates from cruciferous vegetables or of Genistein from soybean in a dietary program that might potentially reduce the risk of BC in large populations.

Isoquercitrin suppresses colon cancer cell growth in vitro by targeting the Wnt/β-catenin signaling pathway

Flavonoids are plant-derived polyphenolic molecules that have potential biological effects including anti-oxidative, anti-inflammatory, anti-viral, and anti-tumoral effects. These effects are related to the ability of flavonoids to modulate signaling pathways, such as the canonical Wnt signaling pathway. This pathway controls many aspects of embryonic development and tissue maintenance and has been found to be deregulated in a range of human cancers. We performed several in vivo assays in Xenopus embryos, a functional model of canonical Wnt signaling studies, and also used in vitro models, to investigate whether isoquercitrin affects Wnt/β-catenin signaling. Our data provide strong support for an inhibitory effect of isoquercitrin on Wnt/β-catenin, where the flavonoid acts downstream of β-catenin translocation to the nuclei. Isoquercitrin affects Xenopus axis establishment, reverses double axes and the LiCl hyperdorsalization phenotype, and reduces Xnr3 expression. In addition, this flavonoid shows anti-tumoral effects on colon cancer cells (SW480, DLD-1, and HCT116), whereas exerting no significant effect on non-tumor colon cell (IEC-18), suggesting a specific effect in tumor cells in vitro. Taken together, our data indicate that isoquercitrin is an inhibitor of Wnt/β-catenin and should be further investigated as a potential novel anti-tumoral agent.

Paris saponin VII inhibits metastasis by modulating matrix metalloproteinases in colorectal cancer cells

Metastasis is the main cause of mortality of patients with cancer-related disease. Targeting the process of metastasis has been proposed as a potential strategy in cancer treatment. Trillium tschonoskii Maxim., a traditional Chinese medicine, is used for the treatment of numerous diseases, including cancer. The current study aimed to determine the anti-metastatic effect of Paris saponin VII (PS VII), which was extracted from T. tschonoskii Maxim., using SW620 and LoVo cells, two human metastatic colorectal cancer (CRC) cell lines. The present study conducted cell attachment, wound healing and migration assays to detect the anti-metastatic effects of PS VII on colorectal cells. In addition, gelatin zymography assay and western blot analysis were used to detect the possible mechanisms involved. The results of this study demonstrated that PS VII significantly suppresses the viability, attachment, migration and invasive abilities of CRC cells in a concentration-dependent manner. In addition, PS Ⅶ reduced the expression levels and activity of matrix metalloproteinase (MMP)-2 and MMP-9. These data indicate that PS VII reduces the metastatic capability of CRC cells, possibly via the downregulation of the expression and activity of MMP-2 and MMP-9. These results demonstrate a novel therapeutic potential for PS VII in anti-metastatic therapy.

Anticancer activities of pterostilbene-isothiocyanate conjugate in breast cancer cells: involvement of PPARγ

Trans-3,5-dimethoxy-4'-hydroxystilbene (PTER), a natural dimethylated analog of resveratrol, preferentially induces certain cancer cells to undergo apoptosis and could thus have a role in cancer chemoprevention. Peroxisome proliferator-activated receptor γ (PPARγ), a member of the nuclear receptor superfamily, is a ligand-dependent transcription factor whose activation results in growth arrest and/or apoptosis in a variety of cancer cells. Here we investigated the potential of PTER-isothiocyanate (ITC) conjugate, a novel class of hybrid compound (PTER-ITC) synthesized by appending an ITC moiety to the PTER backbone, to induce apoptotic cell death in hormone-dependent (MCF-7) and -independent (MDA-MB-231) breast cancer cell lines and to elucidate PPARγ involvement in PTER-ITC action. Our results showed that when pre-treated with PPARγ antagonists or PPARγ siRNA, both breast cancer cell lines suppressed PTER-ITC-induced apoptosis, as determined by annexin V/propidium iodide staining and cleaved caspase-9 expression. Furthermore, PTER-ITC significantly increased PPARγ mRNA and protein levels in a dose-dependent manner and modulated expression of PPARγ-related genes in both breast cancer cell lines. This increase in PPARγ activity was prevented by a PPARγ-specific inhibitor, in support of our hypothesis that PTER-ITC can act as a PPARγ activator. PTER-ITC-mediated upregulation of PPARγ was counteracted by co-incubation with p38 MAPK or JNK inhibitors, suggesting involvement of these pathways in PTER-ITC action. Molecular docking analysis further suggested that PTER-ITC interacted with 5 polar and 8 non-polar residues within the PPARγ ligand-binding pocket, which are reported to be critical for its activity. Collectively, our observations suggest potential applications for PTER-ITC in breast cancer prevention and treatment through modulation of the PPARγ activation pathway.

The antiproliferative response of indole-3-carbinol in human melanoma cells is triggered by an interaction with NEDD4-1 and disruption of wild-type PTEN degradation

Human melanoma cells displaying distinct PTEN genotypes were used to assess the cellular role of this important tumor-suppressor protein in the antiproliferative response induced by the chemopreventative agent indole-3-carbinol (I3C), a natural indolecarbinol compound derived from the breakdown of glucobrassicin produced in cruciferous vegetables such as broccoli and Brussels sprouts. I3C induced a G1-phase cell-cycle arrest and apoptosis by stabilization of PTEN in human melanoma cells that express wild-type PTEN, but not in cells with mutant or null PTEN genotypes. Importantly, normal human epidermal melanocytes were unaffected by I3C treatment. In wild-type PTEN-expressing melanoma xenografts, formed in athymic mice, I3C inhibited the in vivo tumor growth rate and increased PTEN protein levels in the residual tumors. Mechanistically, I3C disrupted the ubiquitination of PTEN by NEDD4-1 (NEDD4), which prevented the proteasome-mediated degradation of PTEN without altering its transcript levels. RNAi-mediated knockdown of PTEN prevented the I3C-induced apoptotic response, whereas knockdown of NEDD4-1 mimicked the I3C apoptotic response, stabilized PTEN protein levels, and downregulated phosphorylated AKT-1 levels. Co-knockdown of PTEN and NEDD4-1 revealed that I3C-regulated apoptotic signaling through NEDD4-1 requires the presence of the wild-type PTEN protein. Finally, in silico structural modeling, in combination with isothermal titration calorimetry analysis, demonstrated that I3C directly interacts with purified NEDD4-1 protein.

IMPLICATIONS

This study identifies NEDD4-1 as a new I3C target protein, and that the I3C disruption of NEDD4-1 ubiquitination activity triggers the stabilization of the wild-type PTEN tumor suppressor to induce an antiproliferative response in melanoma. Mol Cancer Res; 12(11); 1621-34. ©2014 AACR.

Pomegranate fruit as a rich source of biologically active compounds

Pomegranate is a widely used plant having medicinal properties. In this review, we have mainly focused on the already published data from our laboratory pertaining to the effect of methanol extract of pericarp of pomegranate (PME) and have compared it with other relevant literatures on Punica. Earlier, we had shown its antiproliferative effect using human breast (MCF-7, MDA MB-231), and endometrial (HEC-1A), cervical (SiHa, HeLa), and ovarian (SKOV3) cancer cell lines, and normal breast fibroblasts (MCF-10A) at concentration of 20-320 μg/mL. The expressions of selected estrogen responsive genes (PR, pS2, and C-Myc) were downregulated by PME. Unlike estradiol, PME did not increase the uterine weight and proliferation in bilaterally ovariectomized Swiss-Albino mice models and its cardioprotective effects were comparable to that of 17 β -estradiol. We had further assessed the protective role of PME on skeletal system, using MC3T3-E1 cells. The results indicated that PME (80 μg/mL) significantly increased ALP (Alkaline Phosphatase) activity, supporting its suggested role in modulating osteoblastic cell differentiation. The antiosteoporotic potential of PME was also evaluated in ovariectomized (OVX) rodent model. The results from our studies and from various other studies support the fact that pomegranate fruit is indeed a source of biologically active compounds.