BACKGROUND:Cancer is a multistep process involving genetic and epigenetic changes in the somatic genome. Genetic mutations as well as environmental factors lead to the initiation, promotion, and progression of cancer. Metastasis allows cancer cells to spread via circulatory and lymphatic systems; secondary tumorigenesis typically leads to a fatal outcome. Recent experimental evidence suggests that Cancer Stem Cells (CSCs) play a pivotal role in tumor progression. A tumor is heterogeneous and composed of different cell types. CSCs are a subpopulation of tumor cells possessing abilities to self-renew and differentiate.OBJECTIVE:The aim of this study was to present repurposed drugs, and potential candidates, that can serve as anticancer medications intended to target resistant cancer cells, i.e. CSCs.METHODS:Research publications, FDA filings, and patents have been reviewed for repurposed drugs or drug combinations that can act to improve cancer treatment and care.RESULTS:Drugs that act against CSCs include ones approved for treatment of diabetes (metformin & thiazolidinediones), parasitic diseases (chloroquine, niclosamide, mebendazole & pyrvinium), psychotic disorders (thioridazine, clomipramine & phenothiazines), alcoholism (disulfiram), lipid disorder (statins), inflammatory diseases (tranilast, auranofin, acetaminophen & celecoxib), antibiotics (azithromycin), and other disorders. Current research findings advocate the existence of beneficial effects by combining these repurposed drugs, and also through their complementary use with conventional cancer therapies.CONCLUSION:Repurposing FDA-approved medications towards cancer care, by targeting the resistant CSCs, will allow for a quicker, cheaper development and approval process. A larger drug library available to physicians will allow for increased efficacy during both first-line and recurrent cancer treatments.

Entomologists often get “bug” samples for identification, including those that accidentally infest residences. In the United States, we are fortunate to have very few arthropods (e.g., insects, spiders, mites, ticks, etc.) that actually infest or feed on humans. Rarely, samples come from the human body, most often fleas, lice and mites. Table 1 lists the most common arthropods in North America that can infest or feed on humans. In addition, only a few arthropods infest and cause damage to structures, and include: carpenter ants, termites, powderpost beetles, carpet beetles, and clothes moths. Ryan S. Davis Arthropod Diagnostician

Diet and microbiota each have a direct impact on many chronic, inflammatory, and metabolic diseases. As the field develops, a new perspective is emerging. The effects of diet may depend on the microbiota composition of the intestine. A diet that is rich in choline, red meat, dairy, or egg may promote the growth, or change the composition, of microbial species. The microbiota, in turn, may produce metabolites that increase the risk of cardiovascular disease. This article reviews our current understanding of the effects of the molecule trimethylamine-N-oxide (TMAO) obtained from food or produced by the microbiota. We review the mechanisms of actions of TMAO, and studies that associate it with cardiovascular and chronic kidney diseases. We introduce a novel concept: TMAO is one among a group of selective uremic toxins that may rise to high levels in the circulation or accumulate in various organs. Based on this information, we evaluate how TMAO may harm, by exacerbating inflammation, or may protect, by attenuating amyloid formation, in autoimmune diseases such as rheumatoid arthritis.

The tumor microenvironment is complex with the cancer stem cell (CSC) as a member within its community. This population possesses the capacity to self-renew and to cause cellular heterogeneity of the tumor. CSCs are resistant to conventional anti-proliferative drugs. In order to be curative, it is imperative that CSCs must be eliminated by cancer therapy. A variety of dietary phytochemicals and repositioned drugs can act synergistically with conventional anti-cancer agents. In this review, we advocate the development of a novel approach, namely combination therapy by incorporating both phytochemicals and repositioned drugs to target CSCs. We cover select dietary phytochemicals (curcumin, resveratrol, EGCG, genistein) and repurposed drugs (metformin, niclosamide, thioridazine, chloroquine). Five of the eight (curcumin, resveratrol, EGCG, genistein, metformin) are listed in "The Halifax Project", that explores "the concept of a low-toxicity 'broad-spectrum' therapeutic approach that could simultaneously target many key pathways and mechanisms" [1]. For these compounds, we discuss their mechanisms of action, in which models their anti-CSC activities were identified, as well as advantages, challenges and potentials of combination therapy.

Introduction: Development of non-invasive molecular imaging techniques that are based on cellular changes in inflammation has been of active interest for arthritis diagnosis.This technology will allow real-time detection of tissue damage and facilitate earlier treatment of the disease, thus representing an improvement over X-rays, which detect bone damage at the advanced stage.Tracing apoptosis, an event occurring in inflammation, has been a strategy used.PSVue 794 is a low-molecular-weight, near-infrared (NIR)-emitting complex of bis(zinc 2+ -dipicolylamine) (Zn-DPA) that binds to phosphatidylserine (PS), a plasma membrane anionic phospholipid that becomes flipped externally upon cell death by apoptosis.In this study, we evaluated the capacity of PSVue 794 to act as an in vivo probe for non-invasive molecular imaging assessment of rheumatoid arthritis (RA) via metabolic function in murine collagen-induced arthritis, a widely adopted animal model for RA.Methods: Male DBA/1 strain mice were treated twice with chicken collagen type II in Freund's adjuvant.Their arthritis development was determined by measuring footpad thickness and confirmed with X-ray analysis and histology.In vivo imaging was performed with the NIR dye and the LI-COR Odyssey Image System.The level of emission was compared among mice with different disease severity, non-arthritic mice and arthritic mice injected with a control dye without the Zn-DPA targeting moiety.Results: Fluorescent emission correlated reliably with the degree of footpad swelling and the manifestation of arthritis.Ex vivo examination showed emission was from the joint.Specificity of binding was confirmed by the lack of emission when arthritic mice were given the control dye.Furthermore, the PS-binding protein annexin V displaced the NIR dye from binding, and the difference in emission was numerically measurable on a scale.Conclusions: This report introduces an economical alternative method for assessing arthritis non-invasively in murine models.Inflammation in feet and ankles can be measured longitudinally using the PSVue 794 probe for cell death and with a commonly available multipurpose imager.This technique provides metabolic and functional information that anatomical measurement of footpad swelling or visual determination of arthritic index cannot.It also may decrease the number of animals required per experiment because tissue damage will not necessarily require evaluation by harvesting joints for histology.

The objective of this special issue is to present current findings on how PPARs can tilt the delicate balance between host defense and parasite survival to affect the outcome of parasitic infections. The volume contains five comprehensive reviews and one original research article that describe the mechanisms of action of PPARs on several parasitic diseases which infect differently. The pathogens include the malaria parasite Plasmodium falciparum which invades hepatocytes and erythrocytes, the Leishmania species which infect macrophages, the intracellular protozoan Trypanosoma cruzi which invades all tissues, and the helminth Schistosoma species, which live in extracellular environment of specific organs. Whereas it is well known that many parasitic diseases are exacerbated by the activation of T helper 2, recent research on the anti-inflammatory alternatively activated macrophage (AAM), which is activated by PPARγ, shows that there is another facet to the host immune response [1]. PPARγ primes the differentiation of macrophages towards AAM rather than the proinflammatory classically activated macrophage (CAM) phenotype, by promoting arginase while suppressing inducible nitric oxide synthase expression. This activity favors the survival of pathogens, which may be susceptible to the free radical nitric oxide. On the other hand, PPARγ activation becomes beneficial to the host in malaria. This special issue presents studies that, timely, characterize the interaction between parasites and these macrophages which express the PPAR nuclear factors. Malaria is the most devastating among diseases of parasitic protozoa. L. Serghides explains how PPAR agonists relieve immunopathology in cerebral malaria. PPARγ-mediated transcription of CD36, a scavenger receptor which enhances phagocytosis and facilitates the removal of parasitized erythrocytes, leads to reduced parasitemia. In addition, the anti-inflammatory action of PPARγ protects the central nervous system from inflammation-mediated destruction. Y. Ren concurs that the strategy to augment the upregulation of CD36 is potentially therapeutic. Using PPARγ agonist rosiglitazone as adjunctive therapy during treatment of cerebral malaria has successfully gone through phase I/IIa trial in Thailand and now awaits a final randomized double-blind placebo-controlled clinical trial. On the contrary, PPAR activation may benefit the parasite in other infections. For protozoan parasites, trypanosomatids set as examples. M. Chan et al. describe how the activation of PPARα and PPARγ by cutaneous and visceral Leishmania species may promote their survival within macrophages. E. Hovsepian et al. also discuss how Trypanosoma cruzi-mediated PPAR activation influences intracellular parasite survival. For metazoan parasites, B. Anthony et al. review how the Schistosoma species activate PPARα, PPARγ, and AAM to potentiate survival. The PPARγ agonist rosiglitazone has been shown to possess anti-inflammatory, neuroprotective and neuroregenerative properties. However, although rosiglitazone (drug name Avandia, from GlaxoSmithKline) is still being used to treat type 2 diabetes in the United States, the drug is withdrawn in Europe because of adverse effects, especially to the heart. Pioglitazone may be a better alternative. Extending from rosiglitazone and PPARγ, K. Chen et al. report the protective activity of Wy14643, an agonist of PPARα, the isoform prevalent in the liver, towards hypoxia reoxygenation injury in rodent hepatocytes. Many parasitic diseases are widespread in developing countries. Historically, they have been regarded as “neglected tropical diseases” [2]. With parasitic infections being increasingly diagnosed in developed countries due to global travel and immigration, their control is being pursued by many investigators [3, 4]. Public and private agencies, such as TDR, Special Programme for Research and Training in Tropical Diseases of World Health Organization, and Bill & Melinda Gates Foundation, using arrangements such as public-private partnerships, are determined to target such diseases of poverty. Scientists from many countries are actively researching various aspects of parasitic diseases. With this background, we sincerely thank the international cast of scientists who have contributed to this special issue on PPARs and parasites. They come from different countries: Argentina, Australia, Canada, China, United Kingdom, and United States, covering the continents Australia, Europe, North, and South America. In summary, this special issue provides a glimpse of our contemporary understanding on PPAR involvement in parasitic diseases. Different angles have been explored, for example, while PPAR agonists may decrease immunopathology of cerebral malaria, they may enhance parasite survival in leishmaniasis. We hope the readers will find this special issue of PPAR Research informative and will be inspired to make their own contributions to the challenge our world faces from the diverse parasitic infections.

AbstractThe development of anti‐inflammatory therapeutics is an active area of pharmacological research. As we look forward to future discoveries, it also pays to look to the past for potentially useful but neglected therapeutic agents. One example is thalidomide, the drug that had caused a birth defect disaster. Another is cannabinoid, the molecule that has been associated with substance abuse. More targets for anti‐inflammatory therapeutics have been and will be discovered. In this chapter, we will provide two examples: SAHA and catecholamines.

Parasitic infections induce a magnitude of host responses. At the opposite ends of the spectrum are those that ensure the host's needs to eliminate the invaders and to minimize damage to its own tissues. This review analyzes how parasites would manipulate immunity by activating the immunosuppressive nuclear factor, peroxisome proliferator-activated receptors (PPARs) with type 2 cytokines and free fatty acids from arachidonic acid metabolism. PPARs limit the action of type 1 immunity, in which classically activated macrophages act through the production of proinflammatory signals, to spare the parasites. They also favor the development of alternately activated macrophages which control inflammation so the host would not be destroyed. Possibly, the nuclear factors hold a pivotal role in the establishment of chronic infection by delicately balancing the pro- and anti-inflammatory signaling mechanisms and their ligands may be used as combination therapeutics to limit host pathology.

The phytochemical curcumin, from the Indian spice turmeric, has many biological properties, including anti-inflammatory and anti-carcinogenic activities. We have examined the effects of curcumin on the rat C6 glioma cell line. Treated and control cells were analyzed by Hoechst 33342 dye and flow cytometry. We observed a decrease in the side population (SP) of C6 cells after daily curcumin treatment of the C6 cells. Direct incubation of curcumin to C6 cells during the Hoechst assay also decreased SP. Since SP has been associated with stem cell populations, curcumin may be a dietary phytochemical with potential to target cancer stem cells.

Cancer drug resistance is a major cause of treatment failure. Various cancer chemopreventive phytochemicals can sensitize chemoresistant and radioresistant cancer cells. From in vitro tissue culture and in vivo xenograft studies with drug-resistant human cancer cell lines, synergistic effects have been shown between cancer therapeutics and molecules isolated from the spice turmeric, the beverages such as green tea and red wine, other sources of dietary fruits, vegetables, and grains, as well as herbal medicine. However, concerns on safety and bio-accessibility must be addressed further, and the proof-of-concept clinical data, to date, are still missing.

Ovarian cancer is the most lethal of all gynecologic malignancies in the western world Worldwide there will be almost 200,000 cases diagnosed per year and approximately 115,000 deaths. Sixty percent of patients are diagnosed with an already advanced disease. Drug resistance and relapse frequently occur within 2 years of initial treatment. Current treatment is surgery followed by chemotherapy, usually a regimen of platinum/taxane combination. Platinum analogs such as cisplatin act by forming intrastrand cross-links with DNA, whereas taxanes such as paclitaxel act by binding to the cytoskeletal tubulin proteins. The two drugs are administered intravenously, although the intraperitoneal route has recently been shown to improve patient survival, in spite of demonstrated drug toxicity. Hence, searching for less toxic chemotherapeutic agents and strategies of drug resistance reversal are urgently needed, as well as novel therapeutic approaches based on concepts to prevent or circumvent drug resistance. Resistance can involve decreased drug uptake, increased drug efflux, increased repair of DNA damaged by chemotherapy, or reduced ability to undergo apoptosis. Drugs for platinum/taxane-resistant ovarian cancer cells are currently undergoing various stages of development, from cell culture studies to clinical trials For example, TLK-286 (Telcyta), a glutathione S-transferase pi-activated glutathione analog prodrug, shows 15% response in a phase 11 trial. Monoclonal antibodies (against targets such as vascular epithelial growth factor) and RNA interference techniques (small interfering RNA against ATP-binding cassette transporter) are being tested. Other approaches include inhibition of the transcription factor nuclear factor kappa B, with BAY 11-7085, to increase the efficacy of cisplatin, and the use of a nitro derivative of aspirin. NCX-4016, to reverse cisplatin resistance. Many dietary phytochemicals have bioactivity as cancer chemopreventive agents We discovered that curcumin (in the spice turmeric), quercetin (in fruits and vegetables such as apples and onions), and epigallocatechin-3-gallate (EGCG in green tea) enhance cisplatin susceptibility of both cisplatin-sensitive and cisplatin-resistant ovarian cancer cells. Another group has shown that resveratrol (in grapes) also improves the effectiveness of cisplatin In our view, EGCG, the green tea compound is the most promising, because it acts on a variety of cellular pathways and targets. An epidemiological study has concluded that tea consumption leads to a reduced risk of ovarian cancer. These phytochemicals are potentially useful in combination therapy to combat drug resistance in ovarian cancer.

The green tea polyphenol epigallocatechin-3-gallate (EGCG) has cancer chemopreventive properties against various types of cancers. The compound is known to attack various targets in transformed cells. In this report, we examined the action of EGCG on ovarian cancer cells. Eight ovarian cancer cell lines were tested (SKOV3, CAOV3, OVCAR3, OVCAR10, A2780, CP70, C30, and C200) and showed IC(50)s for EGCG at the micromolar range, including ones that are resistant to the chemotherapeutic drug cisplatin. The ovarian cancer cells were sensitive to H2O2 at similar concentrations, and EGCG treatment led to enhanced intracellular H2O2. Neutralization with pyruvate, a scavenger of H2O2, Suggests that the toxicity of EGCG may be mediated by oxidative stress from the free radical. Addition of Tempol, a Superoxide dismutase mimetic, demonstrates that H2O2 might begenerated endogenously from superoxide. The toxicity of cisplatin and the development of cisplatin resistance are major obstacles in treatment of ovarian cancer. We found that addition of EGCG amplified the toxicity of cisplatin. EGCG increased cisplatin potency by three to six-fold ill SKOV3, CAOV3, and C200 cells, the latter being a cell line induced to have several hundred fold resistant to cisplatin above the parental line. Our findings suggest that EGCG may accentuate oxidative stress to inhibit growth of ovarian cancer cells and sensitize them to cisplatin.

Upon Leishmania infection, macrophages are activated to produce nitrogen and oxygen radicals simultaneously. It is well established that the infected host cells rely on nitric oxide (NO) as the major weapon against the intracellular parasite. In India where leishmaniasis is endemic, the spice turmeric is used prolifically in food and for insect bites. Curcumin, the active principle of turmeric, is a scavenger of NO. This report shows that curcumin protects promastigotes and amastigotes of the visceral species, Leishmania donovani , and promastigotes of the cutaneous species, L. major , against the actions of S-nitroso-N-acetyl-D,L-penicillamine (SNAP) and DETANONOate, which release NO, 3-morpholino-sydnonimine hydrochloride (SIN-1), which releases NO and superoxide, and peroxynitrite, which is formed from the reaction of NO with superoxide. Thus, curcumin, as an antioxidant, is capable of blocking the action of both NO and NO congeners on the Leishmania parasite.

Convenient and economical assays capable of screening many compounds are vital to advance the development of drug therapy. This is particularly important for many of the infections that occur mainly in the Third World. The development of such a spectrofluorometric assay for the protozoan parasite Leishmania is presented here. Using multimeric (four monomers) green fluorescent protein (GFP), Leishmania amazonensis promastigotes were generated with brightness measurable in 96-well microtiter plates. The promastigotes maintained the parental characteristics, were infective to murine macrophages and to mice, and the level of GFP fluorescence corresponded to the number of inoculated cells. The feasibility of using this assay for testing drugs kinetically and in a concentration-dependent manner, under microplate culture condition, was demonstrated with amphotericin B and the herbicide oryzalin, respectively. This assay is the first to allow a real-time analysis of antileishmanial agents with live promastigotes. The method of expressing multimeric GFP for in vitro drug screening is likely to be extendable to many species of parasitic protozoa.

The polyphenolic compounds curcumin and quercetin increased sensitivity of ovarian cancer cells (CAOV3 and SKOV3) to cisplatin. The effect was obtained when the compounds were added simultaneously with cisplatin, as well as when they were added 24 h before. High serum levels of certain cytokines, for example interleukin‐6 (IL‐6), have been associated with poor prognosis and cisplatin resistance in various forms of cancer. Furthermore, it has been hypothesized that cytokines may increase proliferation, metastasis, and stimulate production of detoxification enzymes and multi‐drug resistant proteins. Curcumin inhibits the production of many cytokines. The two ovarian cell lines differ significantly in IL‐6 production, and correspondingly the high producer, CAOV3, was less susceptible to cisplatin. Curcumin inhibited the production of IL‐6 in this cell suggesting that one of the mechanisms for synergy between cisplatin and curcumin was by reducing the autologous production of IL‐6. However, the synergy was also observed in the low IL‐6 producer, SKOV3, indicating that the action was most probably a result of multiple targeting. In sum, this study suggests that the compounds, curcumin and quercetin, potentially may be useful for enhancing drug sensitivity in certain cancer. J. Cell. Physiol. 194: 63–70, 2002. © 2002 Wiley‐Liss, Inc.

N-Formyl-methionyl peptides can specifically bind to surface receptors on phagocytic cells. A single copy of N-formyl-methionine-leucine-phenylalanine (fMLF) covalently linked to a poly(ethylene glycol)-based polymer displayed reduced binding avidity (K(d) = 190 nM) for differentiated HL-60 cells relative to free fMLF (K(d) = 28 nM). Increasing the number of fMLF residues (up to eight) attached to a single polymer results in enhanced avidity for these cells (K(d) = 0.18 nM), which appears to be independent of whether the polymer backbone is linear or branched. However, no conjugate showed enhanced ability to activate phagocytic cells, relative to the free peptide (EC(50) = 5 nM), as measured by transient stimulation of release of calcium ions from intracellular stores into the cytoplasm. A polymer bearing four fMLF and four digoxigenin residues showed specific enhancement in binding to differentiated HL-60 cells and mouse peritoneal macrophages in situ relative to a polymer lacking fMLF; no such enhancement was seen in binding to receptor-negative lymphocytic Jurkat cells. These results suggest that multiple fMLF residues linked to a drug-delivery polymer can be used to target appended drugs to phagocytic cells with relatively little toxicity due to cellular activation.

Curcumin, a phytochemical with antioxidant and anti-inflammatory properties, is valued as a cancer chemopreventive agent. Previously, we have shown that curcumin reduces the gene expression of inducible nitric oxide synthase (iNOS) in murine macrophages, in vitro, and in the liver, in vivo. Here, we continued to examine its effect on iNOS expression in other organs. Curcumin inhibited lipopolysaccharide (LPS)-induced iNOS gene expression in the spleen, mesenteric lymph nodes, small intestine and colon. Furthermore, it inhibited gene expression of three cytokines that enhance iNOS production. In vitro, curcumin reduced the gene expression of tumor necrosis factor a (TNFalpha) and interleukin-1beta (IL-1beta) by LPS-stimulated peritoneal cells. In vivo, it reduced the gene expression of TNFa and IL-1beta in the liver and spleen, and reduced the gene expression of interferon gamma (IFNgamma) in the spleen and lymph nodes. Nitric oxide (NO) enhances the activity of cyclooxygenase-2 (COX-2); we found that curcumin also reduced COX-2 gene expression in RAW 264.7 macrophages.

In atherosclerosis and tumor initiation, inducible nitric oxide synthase (iNOS) has been implicated in the damage of vascular walls and DNA, respectively. Moderate consumption of red wine has been ascribed as a preventive for coronary heart disease; however, there has been much debate over whether the beneficial effect is from grape polyphenolic components or ethanol. We studied the interaction of grape compounds on nitric oxide (NO) production by macrophages, mediators of blood vessel damage in atherosclerosis. For the murine macrophage cell line RAW 264.7, stimulation with lipopolysaccharide and interferon-γ led to expression of the iNOS gene and production of NO. The polyphenols quercetin and resveratrol at a micromolar range suppressed iNOS gene expression and NO production, as determined by reverse transcription–polymerase chain reaction and nitrite assay. The polyphenols were also found to be scavengers of NO in an acellular system using sodium nitroprusside under physiological conditions. Ethanol, at a moderate level, did not produce any appreciable level of reduction of iNOS or NO activity. However, its presence at 0.1 to 0.75% enhanced the effect of grape polyphenols concentration-dependently. Thus, the interaction between these components plays a significant role in the health effects of red wine, especially with respect to their effect on the NO pathway.