Panaxynol improves crypt and mucosal architecture, suppresses colitis-enriched microbes, and alters the immune response to mitigate colitis

Ulcerative colitis (UC) is an idiopathic inflammatory disease of the large intestine, which impacts millions worldwide. Current interventions aimed at treating UC symptoms can have off-target effects, invoking the need for alternatives that may provide similar benefits with less unintended consequences. This study builds on our initial data, which showed that panaxynol - a novel, potent, bioavailable compound found in American ginseng - can suppress disease severity in murine colitis. Here we explore the underlying mechanisms by which panaxynol improves both chronic and acute murine colitis. 14-week-old C57BL/6 female mice were either given 3 rounds of dextran sulfate sodium (DSS) in drinking water to induce chronic colitis or 1 round to induce acute colitis. Vehicle or panaxynol (2.5 mg/kg) was administered via oral gavage 3x/week for the study duration. Consistent with our previous findings, panaxynol significantly (p<0.05) improved the disease activity index and endoscopic scores in both models. Using the acute model to examine potential mechanisms, we show that panaxynol significantly (p<0.05) reduced DSS-induced crypt distortion, goblet cell loss, and mucus loss in the colon. 16s sequencing revealed panaxynol altered microbial composition to suppress colitis-enriched genera (i.e., Enterococcus, Eubacterium, and Ruminococcus). Additionally, panaxynol significantly (p<0.05) suppressed macrophages and induced regulatory T-cells in the colonic lamina propria. The beneficial effects of panaxynol on mucosal and crypt architecture, combined with its microbial and immune-mediated effects, provide insight into mechanisms by which panaxynol suppresses murine colitis. Overall, this data is promising for the use of panaxynol to improve colitis in the clinic.

The synthetic food dye, Red 40, causes DNA damage, causes colonic inflammation, and impacts the microbiome in mice

The incidence of colorectal cancer (CRC) among young people has been on the rise for the past four decades and its underlying causes are only just starting to be uncovered. Recent studies suggest that consuming ultra-processed foods and pro-inflammatory diets may be contributing factors. The increase in the use of synthetic food colors in such foods over the past 40 years, including the common synthetic food dye Allura Red AC (Red 40), coincides with the rise of early-onset colorectal cancer (EOCRC). As these ultra-processed foods are particularly appealing to children, there is a growing concern about the impact of synthetic food dyes on the development of CRC. Our study aimed to investigate the effects of Red 40 on DNA damage, the microbiome, and colonic inflammation. Despite a lack of prior research, high levels of human exposure to pro-inflammatory foods containing Red 40 highlight the urgency of exploring this issue. Our results show that Red 40 damages DNA both in vitro and in vivo and that consumption of Red 40 in the presence of a high-fat diet for 10 months leads to dysbiosis and low-grade colonic inflammation in mice. This evidence supports the hypothesis that Red 40 is a dangerous compound that dysregulates key players involved in the development of EOCRC.

Panaxynol alleviates colorectal cancer in a murine model via suppressing macrophages and inflammation

Currently available colorectal cancer (CRC) therapies have limited efficacy and severe adverse effects that may be overcome with the alternative use of natural compounds. We previously reported that panaxynol (PA), a bioactive component in American ginseng, possesses anticancer properties in vitro and suppresses murine colitis through its proapoptotic and anti-inflammatory properties. Because colitis is a predisposing factor of CRC and inflammation is a major driver of CRC, we sought to evaluate the therapeutic potential of PA in CRC. Azoxymethane-dextran sodium sulfate (AOM/DSS) mice (C57BL/6) were administered 2.5 mg/kg PA or vehicle 3 times/wk via oral gavage over 12 wk. PA improved clinical symptoms (P ≤ 0.05) and reduced tumorigenesis (P ≤ 0.05). This improvement may be reflective of PA's restorative effect on intestinal barrier function; PA upregulated the expression of essential tight junction and mucin genes (P ≤ 0.05) and increased the abundance of mucin-producing goblet cells (P ≤ 0.05). Given that macrophages play a substantial role in the pathogenesis of CRC and that we previously demonstrated that PA targets macrophages in colitis, we next assessed macrophages. We show that PA reduces the relative abundance of colonic macrophages within the lamina propria (P ≤ 0.05), and this was consistent with a reduction in the expression of important markers of macrophages and inflammation (P ≤ 0.05). We further confirmed PA's inhibitory effects on macrophages in vitro under CRC conditions (P ≤ 0.05). These results suggest that PA is a promising therapeutic compound to treat CRC and improve clinical symptoms given its ability to inhibit macrophages and modulate the inflammatory environment in the colon.NEW & NOTEWORTHY We report that panaxynol (PA) reduces colorectal cancer (CRC) by improving the colonic and tumor environment. Specifically, we demonstrate that PA improves crypt morphology, upregulates crucial tight junction and mucin genes, and promotes the abundance of mucin-producing goblet cells. Furthermore, PA reduces macrophages and associated inflammation, important drivers of CRC, in the colonic environment. This present study provides novel insights into the potential of PA as a therapeutic agent to ameliorate CRC tumorigenesis.

Publisher Correction: Early-onset colorectal cancer: initial clues and current views

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Panaxynol, a bioactive component of American ginseng, targets macrophages and suppresses colitis in mice

Ulcerative colitis has a significant impact on the quality of life for the patients, and can substantially increase the risk of colon cancer in patients suffering long-term. Conventional treatments provide only modest relief paired with a high risk of side effects, while complementary and alternative medicines can offer safe and effective options. Over the past decade, we have shown that both American ginseng and its hexane fraction (HAG) have anti-oxidant and anti-inflammatory properties that can suppress mouse colitis and prevent colitis-associated colon cancer. With the goal of isolating a single active compound, we further fractionated HAG, and found the most abundant molecule in this fraction was the polyacetylene, panaxynol (PA). After isolating and characterizing PA, we tested the efficacy of PA in the treatment and prevention of colitis in mice and studied the mechanism of action. We demonstrate here that PA effectively treats colitis in a Dextran Sulfate Sodium mouse model by targeting macrophages for DNA damage and apoptosis. This study provides additional mechanistic evidence that American ginseng can be used for conventional treatment of colitis and other diseases associated with macrophage dysfunction.

Early-onset colorectal cancer: initial clues and current views

Over the past several decades, the incidence of early-onset colorectal cancer (EOCRC; in patients <50 years old) has increased at an alarming rate. Although robust and scientifically rigorous epidemiological studies have sifted out environmental elements linked to EOCRC, our knowledge of the causes and mechanisms of this disease is far from complete. Here, we highlight potential risk factors and putative mechanisms that drive EOCRC and suggest likely areas for fruitful research. In addition, we identify inconsistencies in the evidence implicating a strong effect of increased adiposity and suggest that certain behaviours (such as diet and stress) might place nonobese and otherwise healthy people at risk of this disease. Key risk factors are reviewed, including the global westernization of diets (usually involving a high intake of red and processed meats, high-fructose corn syrup and unhealthy cooking methods), stress, antibiotics, synthetic food dyes, monosodium glutamate, titanium dioxide, and physical inactivity and/or sedentary behaviour. The gut microbiota is probably at the crossroads of these risk factors and EOCRC. The time course of the disease and the fact that relevant exposures probably occur in childhood raise important methodological issues that are also discussed.

Pharmacokinetics of Panaxynol in Mice

The purpose of our study is to explore the pharmacokinetic parameters of panaxynol (PA) and understand its potential and dosage used in pre-clinical animal models. For in vitro analysis,5 μM of PA was added to liver microsomes of mouse and human species. Nicotinamide adenine dinucleotide phosphate was added to initiate enzyme reaction except for the negative control. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis was used to measure concentrations. For in vivo studies, CD-1 mice were treated with PA by intravenous (IV) injection or oral administration (PO). Concentrations of PA were measured in plasma and tissue using LC-MS/MS. Pharmacokinetic parameters were obtained using non-compartmental analysis. Area under the curve concentration versus time was calculated using a linear trapezoidal model.In vitro, PA's half-life is 21.4 min and 48.1 min in mouse and human liver microsomes, respectively. In vivo, PA has a half-life of 1.5 hr when IV-injected, and 5.9 hr when administered via PO, with a moderate bioavailability of 50.4%. Mice show no signs of toxicity up to 300 mg/kg PO. PA concentrations were highest in colon tissue 2 hr post-treatment at 486 ng/g of colon tissue.PA's pharmacokinetic properties and low toxicity point to the safety and compatibility of PA with mice.

Acute and short-term administrations of delta-9-tetrahydrocannabinol modulate major gut metabolomic regulatory pathways in C57BL/6 mice

Delta-9-tetrahydrocannabinol (THC) is the primary psychoactive compound in Cannabis, which is studied extensively for its medicinal value. A central gap in the science is the underlying mechanisms surrounding THC's therapeutic effects and the role of gut metabolite profiles. Using a mass-spectrometry based metabolomics, we show here that intraperitoneal injection of THC in C57BL/6 mice modulates metabolic profiles that have previously been identified as integral to health. Specifically, we investigated the effects of acute (single THC injection denoted here as '1X') and short -term (five THC injections on alternate days denoted as '5X') THC administration on fecal and intestinal tissue metabolite profiles. Results are consistent with the hypothesis that THC administration alters host metabolism by targeting two prominent lipid metabolism pathways: glycerophospholipid metabolism and fatty acid biosynthesis.

Maternal stress and early-onset colorectal cancer

Early-onset colorectal cancer (EOCRC) is defined as colorectal cancer (CRC) diagnosed before the age of 50. Alarmingly, there has been a significant increase in EOCRC diagnoses' worldwide over the past several decades. Emerging data suggest EOCRCs have distinguishing clinical, pathological, biological and molecular features; and thus, are a fundamentally different subtype of CRCs. Unfortunately, there is no simple explanation for the causes of EOCRC. Scientifically rigorous studies are needed to determine what may be driving the challenging epidemiology of EOCRC. We contend here that a reasonable hypothesis is that prenatal risk factors such as maternal stress and associated sleeping disorders influence offspring epigenetic make-up, and shape immune system and gut health contributing to an increased risk for EOCRC.

Dietary inflammatory index and odds of colorectal cancer in a case-control study from Jordan

Dietary components that promote inflammation of the colon have been suggested to be risk factors in the development of colorectal cancer (CRC). The possible link between inflammatory potential of diet and CRC has been investigated in several developed or Western countries. Despite the fact that dietary choices in the Middle East differ markedly from those in the West, results have not been reported from any study conducted in a Middle-Eastern population. We examined the association between dietary inflammatory index (DII) scores and CRC in a case-control study conducted in Jordan. This study included 153 histopathologically confirmed CRC cases and 202 disease-free control subjects' frequency matched on age, sex, and occupation. Data were collected between January 2010 and December 2012, using interviewer-administered questionnaires. DII scores were computed from dietary data reported using a food frequency questionnaire. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for age, sex, education, physical activity, body mass index, smoking, and family history of CRC. Subjects with higher DII scores were at increased odds of CRC, with the DII being used both as a continuous variable (OR_continuous = 1.45, 95% CI: 1.13-1.85; 1-unit increase corresponding to ≈20% of its range in the current study) and as a categorical variable (OR_{tertile 3 vs tertile 1} = 2.13, 95%CI: 1.23-3.72). Our results, based on a Jordanian population, add to the growing literature indicating that a pro-inflammatory diet is associated with increased odds of CRC.

Molecular targeting of protein arginine deiminases to suppress colitis and prevent colon cancer

Ulcerative colitis (UC) is a chronic disease, in which the lining of the colon becomes inflamed and develops ulcers leading to abdominal pain, diarrhea, and rectal bleeding. The extent of these symptoms depends on disease severity. The protein arginine deiminase (PAD) family of enzymes converts peptidyl-Arginine to peptidyl-Citrulline through citrullination. PADs are dysregulated, with abnormal citrullination in many diseases, including UC and colorectal cancer (CRC). We have developed the small molecule, pan-PAD inhibitor, Chlor-amidine (Cl-amidine), with multiple goals, including treating UC and preventing CRC. Building off our recent results showing that: 1) Cl-amidine suppresses colitis in vivo in a dextran sulfate sodium (DSS) mouse model; and 2) Cl-amidine induces microRNA (miR)-16 in vitro causing cell cycle arrest, we tested the hypothesis that Cl-amidine can prevent tumorigenesis and that miR-16 induction, by Cl-amidine, may be involved in vivo. Consistent with our hypothesis, we present evidence that Cl-amidine, delivered in the drinking water, prevents colon tumorigenesis in our mouse model of colitis-associated CRC where mice are given carcinogenic azoxymethane (AOM), followed by multiple cycles of 2% DSS to induce colitis. To begin identifying mechanisms, we examined the effects of Cl-amidine on miR-16. Results show miR-16 suppression during the colitis-to-cancer sequence in colon epithelial cells, which was rescued by drinking Cl-amidine. Likewise, Ki67 and cellular proliferation targets of miR-16 (Cyclins D1 and E1) were suppressed by Cl-amidine. The decrease in cell proliferation markers and increase in tumor suppressor miRNA expression potentially define a mechanism of how Cl-amidine is suppressing tumorigenesis in vivo.

Designing a broad-spectrum integrative approach for cancer prevention and treatment

Targeted therapies and the consequent adoption of "personalized" oncology have achieved notable successes in some cancers; however, significant problems remain with this approach. Many targeted therapies are highly toxic, costs are extremely high, and most patients experience relapse after a few disease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistant immortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are not reliant upon the same mechanisms as those which have been targeted). To address these limitations, an international task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspects of relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a wide range of high-priority targets (74 in total) that could be modified to improve patient outcomes. For these targets, corresponding low-toxicity therapeutic approaches were then suggested, many of which were phytochemicals. Proposed actions on each target and all of the approaches were further reviewed for known effects on other hallmark areas and the tumor microenvironment. Potential contrary or procarcinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixed evidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of the relationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. This novel approach has potential to be relatively inexpensive, it should help us address stages and types of cancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for future research is offered.

Protein Arginine Deiminases and Associated Citrullination: Physiological Functions and Diseases Associated with Dysregulation

Human proteins are subjected to more than 200 known post-translational modifications (PTMs) (e.g., phosphorylation, glycosylation, ubiquitination, S-nitrosylation, methylation, Nacetylation, and citrullination) and these PTMs can alter protein structure and function with consequent effects on the multitude of pathways necessary for maintaining the physiological homeostasis. When dysregulated, however, the enzymes that catalyze these PTMs can impact the genesis of countless diseases. In this review, we will focus on protein citrullination, a PTM catalyzed by the Protein Arginine Deiminase (PAD) family of enzymes. Specifically, we will describe the roles of the PADs in both normal human physiology and disease. The development of PAD inhibitors and their efficacy in a variety of autoimmune disorders and cancer will also be discussed.

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.

Abstract 238: Citrullination of miRNA regulators by PADs: A potential mechanism for the promotion of colitis and colitis-associated colorectal cancer

Ulcerative Colitis (UC) is a chronic, relapsing inflammatory bowel disease that affects millions of people worldwide. As a result of DNA damage caused by the chronic inflammatory state of UC, people suffering from UC are at a higher risk of developing colorectal cancer (CRC). Although the cause of UC is still unknown, the protein arginine deiminase (PAD) family of enzymes has been found to be a key component in many human inflammatory diseases and cancer, including UC and CRC. PADs are calcium-dependent enzymes that post-translationally convert positively charged peptidyl-Arginine to neutral peptidyl-Citrulline through a process called ‘citrullination’. In hopes of treating UC and preventing CRC, we developed Chlor-amidine (Cl-amidine), a novel small molecule inhibitor of PADs. Previous results from our group have shown that miR-16, which is often downregulated in cancers, had increased expression levels in mice treated with Cl-amidine. MiR-16 targets (i.e. Cyclin D1 and E1) and colon carcinogenesis were also suppressed in mice treated with Cl-amidine. Our goal is to determine the mechanism(s) by which Cl-amidine targets miR-16 and other tumor suppressor miRNAs. One hypothesis is that Cl-amidine is preventing the citrullination of DNA methyltransferases (DNMTs). Citrullinated DNMTs show hyperactivity, resulting in hypermethylation and subsequent silencing of miRNAs. Evidence suggests that PADs can citrullinate DNMT3A, resulting in ‘methylation-mediated gene silencing’. We predict that this silencing negatively regulates tumor suppressor miRNAs and Cl-amidine treatment will restore these miRNA levels. Initial results suggest citrullination of DNMT3A in our in vitro colon cancer cell line model. Experiments are ongoing to confirm the ability of Cl-amidine to prevent citrullination-induced activation of upstream miRNA regulators. Results from our study will elaborate on the mechanism of action of Cl-amidine and provide further insight into using Cl-amidine as an anti-cancer therapy.

Citation Format: Erin E. Witalison, Xiangli Cui, Corey P. Causey, Paul R. Thompson, Lorne J. Hofseth. Citrullination of miRNA regulators by PADs: A potential mechanism for the promotion of colitis and colitis-associated colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 238. doi:10.1158/1538-7445.AM2015-238

Identifying panaxynol, a natural activator of nuclear factor erythroid-2 related factor 2 (Nrf2) from American ginseng as a suppressor of inflamed macrophage-induced cardiomyocyte hypertrophy

ETHNOPHARMACOLOGICAL RELEVANCE

American ginseng is capable of ameliorating cardiac dysfunction and activating Nrf2, a master regulator of antioxidant defense, in the heart. This study was designed to isolate compounds from American ginseng and to determine those responsible for the Nrf2-mediated resolution of inflamed macrophage-induced cardiomyocyte hypertrophy.

MATERIALS AND METHODS

A standardized crude extract of American ginseng was supplied by the National Research Council of Canada, Institute for National Measurement Standards. A bioassay-based fractionization of American ginseng was performed to identify the putative substances which could activate Nrf2-mediated suppression of pro-inflammatory cytokine expression in macrophages and macrophage-mediated pro-hypertrophic growth in cardiomyocytes.

RESULTS

A hexane fraction of an anti-inflammatory crude extract of American ginseng was found to be most effective in suppressing the inflammatory responses in macrophages. Preparative, reverse-phase HPLC and a comparative analysis by analytical scale LC-UV/MS revealed the hexane fraction contains predominantly C17 polyacetylenes and linolenic acid. Panaxynol, one of the major polyacetylenes, was found to be a potent Nrf2 activator. Panaxynol posttranscriptionally activated Nrf2 by inhibiting Kelch-like ECH-associated protein (Keap) 1-mediated degradation without affecting the binding of Keap1 and Nrf2. Moreover, panaxynol suppressed a selected set of cytokine expression via the activation of Nrf2 while minimally regulating nuclear factor-kappa B (NF-κB)-mediated cytokine expression in macrophages. It also dramatically inhibited the inflamed macrophage-mediated cardiomyocyte death and hypertrophy by activating Nrf2 in macrophages.

CONCLUSIONS

These results demonstrate that American ginseng-derived panaxynol is a specific Nrf2 activator and panaxynol-activated Nrf2 signaling is at least partly responsible for American ginseng-induced health benefit in the heart.

Inhibiting protein arginine deiminases has antioxidant consequences

Ulcerative colitis is a dynamic, idiopathic, chronic inflammatory condition that carries a high colon cancer risk. We previously showed that Cl-amidine, a small-molecule inhibitor of the protein arginine deiminases, suppresses colitis in mice. Because colitis is defined as inflammation of the colon associated with infiltration of white blood cells that release free radicals and citrullination is an inflammation-dependent process, we asked whether Cl-amidine has antioxidant properties. Here we show that colitis induced with azoxymethane via intraperitoneal injection + 2% dextran sulfate sodium in the drinking water is suppressed by Cl-amidine (also given in the drinking water). Inducible nitric oxide synthase, an inflammatory marker, was also downregulated in macrophages by Cl-amidine. Because epithelial cell DNA damage associated with colitis is at least in part a result of an oxidative burst from overactive leukocytes, we tested the hypothesis that Cl-amidine can inhibit leukocyte activation, as well as subsequent target epithelial cell DNA damage in vitro and in vivo. Results are consistent with this hypothesis, and because DNA damage is a procancerous mechanism, our data predict that Cl-amidine will not only suppress colitis, but we hypothesize that it may prevent colon cancer associated with colitis.

Abstract 3782: Cl-amidine, a PAD inhibitor, prevents UC and CRC in mice: Exploring novel mechanisms of miRNA and oxidative stress regulation

Ulcerative Colitis (UC) is a chronic, relapsing inflammatory bowel disease that affects millions of patients worldwide. Due to the chronic inflammatory state of UC, which causes oxidative stress and leads to DNA damage, patients with UC are at a higher risk of developing colorectal cancer (CRC). Although the cause of UC is still unknown, the protein arginine deiminase (PAD) family of enzymes has been found to be a key component in many human inflammatory diseases and cancer, including UC and CRC. PADs are calcium dependent enzymes that post-translationally convert peptidyl-Arginine to peptidyl-Citrulline through ‘citrullination’. In hopes of treating UC and preventing CRC, we developed Chlor-amidine (Cl-amidine), a novel small molecule inhibitor of PADs. Cl-amidine irreversibly inhibits PADs by covalent modification of Cys645 at the active site of the PAD enzyme. Unlike current approved drugs for the treatment of UC, Cl-amidine shows no toxicity both in vitro and in vivo. Preliminary in vitro studies showed that Cl-amidine is able to suppress oxidative stress, DNA damage, and the inflammatory marker, iNOS. Correspondingly, we found similar results in our AOM/DSS mouse model of UC, as Cl-amidine suppressed colonic inflammation. In this UC model, Cl-amidine treatment also decreased reactive oxygen species (ROS) production by inflammatory cells and DNA damage in epithelial cells. We proceeded to look at the capability of Cl-amidine to prevent carcinogenesis in our AOM/DSS mouse model of UC-associated CRC and report that Cl-amidine treatment significantly decreased tumor incidence in this model. To further understand how Cl-amidine prevents carcinogenesis, we are currently exploring the effect of Cl-amidine on two separate mechanisms: 1) miRNA and 2) oxidative stress regulation. First, our recent studies have focused specifically on miR-16, a putative tumor suppressor, which is downregulated in cancers. Interestingly, we have found that Cl-amidine upregulates miR-16 expression in our in vitro and in vivo models of UC. We aim to determine if Cl-amidine acts through miR-16 to prevent UC and UC-associated CRC by suppressing DNA damage and/or by suppressing cell proliferation. The second mechanism that we are exploring involves the regulation of antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase. In vitro results reveal that Cl-amidine increased protein levels of these enzymes. We plan to measure ROS levels in Cl-amidine treated cells that are introduced to SOD, GPx, and catalase inhibitors. This will provide evidence that Cl-amidine is working through these specific enzymes to reduce ROS activity. Based on the efficacy of Cl-amidine in our models of UC and CRC, and its potential multi-targeted mechanism of action; our research has revealed that Cl-amidine is a cutting-edge, prospective drug therapy for UC patients.

Citation Format: Erin E. Witalison, Xiangli Cui, Paul R. Thompson, Lorne J. Hofseth. Cl-amidine, a PAD inhibitor, prevents UC and CRC in mice: Exploring novel mechanisms of miRNA and oxidative stress regulation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3782. doi:10.1158/1538-7445.AM2014-3782

A key role of microRNA-29b for the suppression of colon cancer cell migration by American ginseng

Metastasis of colon cancer cells increases the risk of colon cancer mortality. We have recently shown that American ginseng prevents colon cancer, and a Hexane extract of American Ginseng (HAG) has particularly potent anti-inflammatory and anti-cancer properties. Dysregulated microRNA (miR) expression has been observed in several disease conditions including colon cancer. Using global miR expression profiling, we observed increased miR-29b in colon cancer cells following exposure to HAG. Since miR-29b plays a role in regulating the migration of cancer cells, we hypothesized that HAG induces miR-29b expression to target matrix metalloproteinase-2 (MMP-2) thereby suppressing the migration of colon cancer cells. Results are consistent with this hypothesis. Our study supports the understanding that targeting MMP-2 by miR-29b is a mechanism by which HAG suppresses the migration of colon cancer cells.

The induction of microRNA-16 in colon cancer cells by protein arginine deiminase inhibition causes a p53-dependent cell cycle arrest

Protein Arginine Deiminases (PADs) catalyze the post-translational conversion of peptidyl-Arginine to peptidyl-Citrulline in a calcium-dependent, irreversible reaction. Evidence is emerging that PADs play a role in carcinogenesis. To determine the cancer-associated functional implications of PADs, we designed a small molecule PAD inhibitor (called Chor-amidine or Cl-amidine), and tested the impact of this drug on the cell cycle. Data derived from experiments in colon cancer cells indicate that Cl-amidine causes a G1 arrest, and that this was p53-dependent. In a separate set of experiments, we found that Cl-amidine caused a significant increase in microRNA-16 (miRNA-16), and that this increase was also p53-dependent. Because miRNA-16 is a putative tumor suppressor miRNA, and others have found that miRNA-16 suppresses proliferation, we hypothesized that the p53-dependent G1 arrest associated with PAD inhibition was, in turn, dependent on miRNA-16 expression. Results are consistent with this hypothesis. As well, we found the G1 arrest is at least in part due to the ability of Cl-amidine-mediated expression of miRNA-16 to suppress its' G1-associated targets: cyclins D1, D2, D3, E1, and cdk6. Our study sheds light into the mechanisms by which PAD inhibition can protect against or treat colon cancer.

D-amino acid based protein arginine deiminase inhibitors: Synthesis, pharmacokinetics, and in cellulo efficacy

The protein arginine deiminases (PADs) are known to play a crucial role in the onset and progression of multiple inflammatory diseases, including rheumatoid arthritis, inflammatory bowel disease, and cancer. However, it is not known how each of the five PAD isozymes contributes to disease pathogenesis. As such, potent, selective, and bioavailable PAD inhibitors will be useful chemical probes to elucidate the specific roles of each isozyme. Since D-amino amino acids often possess enhanced in cellulo stability, and perhaps unique selectivities, we synthesized a series of D-amino acid analogs of our pan-PAD inhibitor Cl-amidine, hypothesizing that this change would provide inhibitors with enhanced pharmacokinetic properties. Herein, we demonstrate that d-Cl-amidine and d-o-F-amidine are potent and highly selective inhibitors of PAD1. The pharmacokinetic properties of d-Cl-amidine were moderately improved over those of l-Cl-amidine, and this compound exhibited similar cell killing in a PAD1 expressing, triple-negative MDA-MB-231 breast cancer cell line. These inhibitors represent an important step in our efforts to develop stable, bioavailable, and highly selective inhibitors for all of the PAD isozymes.

Seeing citrulline: development of a phenylglyoxal-based probe to visualize protein citrullination

Protein arginine deiminases (PADs) catalyze the hydrolysis of peptidyl arginine to form peptidyl citrulline. Abnormally high PAD activity is observed in a host of human diseases, but the exact role of protein citrullination in these diseases and the identities of specific citrullinated disease biomarkers remain unknown, largely because of the lack of readily available chemical probes to detect protein citrullination. For this reason, we developed a citrulline-specific chemical probe, rhodamine-phenylglyoxal (Rh-PG), which we show can be used to investigate protein citrullination. This methodology is superior to existing techniques because it possesses higher throughput and excellent sensitivity. Additionally, we demonstrate that this probe can be used to determine the kinetic parameters for a number of protein substrates, monitor drug efficacy, and identify disease biomarkers in an animal model of ulcerative colitis that displays aberrantly increased PAD activity.

Macrophages, nitric oxide and microRNAs are associated with DNA damage response pathway and senescence in inflammatory bowel disease

BACKGROUND

Cellular senescence can be a functional barrier to carcinogenesis. We hypothesized that inflammation modulates carcinogenesis through senescence and DNA damage response (DDR). We examined the association between senescence and DDR with macrophage levels in inflammatory bowel disease (IBD). In vitro experiments tested the ability of macrophages to induce senescence in primary cells. Inflammation modulating microRNAs were identified in senescence colon tissue for further investigation.

METHODOLOGY/PRINCIPAL FINDINGS

Quantitative immunohistochemistry identified protein expression by colon cell type. Increased cellular senescence (HP1γ; P = 0.01) or DDR (γH2A.X; P = 0.031, phospho-Chk2, P = 0.014) was associated with high macrophage infiltration in UC. Co-culture with macrophages (ANA-1) induced senescence in >80% of primary cells (fibroblasts MRC5, WI38), illustrating that macrophages induce senescence. Interestingly, macrophage-induced senescence was partly dependent on nitric oxide synthase, and clinically relevant NO• levels alone induced senescence. NO• induced DDR in vitro, as detected by immunofluorescence. In contrast to UC, we noted in Crohn's disease (CD) that senescence (HP1γ; P<0.001) and DDR (γH2A.X; P<0.05, phospho-Chk2; P<0.001) were higher, and macrophages were not associated with senescence. We hypothesize that nitric oxide may modulate senescence in CD; epithelial cells of CD had higher levels of NOS2 expression than in UC (P = 0.001). Microarrays and quantitative-PCR identified miR-21 expression associated with macrophage infiltration and NOS2 expression.

CONCLUSIONS

Senescence was observed in IBD with senescence-associated β-galactosidase and HP1γ. Macrophages were associated with senescence and DDR in UC, and in vitro experiments with primary human cells showed that macrophages induce senescence, partly through NO•, and that NO• can induce DDR associated with senescence. Future experiments will investigate the role of NO• and miR-21 in senescence. This is the first study to implicate macrophages and nitrosative stress in a direct effect on senescence and DDR, which is relevant to many diseases of inflammation, cancer, and aging.

Abstract LB-168: A hexane fraction of American ginseng suppresses colon cancer associated with colitis

Patients with Ulcerative Colitis (UC) have a high risk of colon cancer. We have recently shown American Ginseng (AG) suppresses colitis, and prevents colon cancer in mice. In the present study we isolated a Hexane Fraction of AG and found this to have particularly potent anti-oxidant and pro-apoptotic properties. The Hexane Fraction of AG was effective in inducing apoptosis of human epithelial colon cancer cell, HCT-116 and inflammatory cells. As well, this fraction was shown to suppress azoxymethane (AOM)/DSS-induced colon cancer. We performed two studies with mice: a short term (Day 35) and long term (Day 50) cancer prevention study. Mice fed the Hexane fraction of AG had significantly less inflammatory and ulcerative lesions, as well as cancerous lesions compared with the vehicle-treated group in both the short and long-term cancer prevention studies. Results are consistent with the hypothesis that the Hexane fraction of AG has anti-inflammatory and anti-cancer properties, and prevents the progression of colon cancer in AOM/DSS mouse model. Interestingly, at Day 35, following isolation of CD45- epithelial cells from colons of mice treated with either AOM+DSS+Vehicle or AOM+DSS+Hexane fraction of AG, there was a 24% increase in the putatative tumor suppressor miRNA-16 with treatment with the Hexane fraction of AG. When looking at putative miRNAs with oncogenic properties (miRNA-21 and -155), levels were decreased in epithelial cells by 25% and 12% respectively in the Hexane fraction of AG-treated mice. This study provides additional pre-clincal data, and mechanistic studies that support the possible use of this complementary and alternative medicine in the treatment of colitis, and the prevention of colon cancer associated with colitis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-168. doi:1538-7445.AM2012-LB-168

Suppression of DNA damage in human peripheral blood lymphocytes by a juice concentrate: a randomized, double-blind, placebo-controlled trial

Chronic inflammation contributes to many prevalent diseases worldwide, and it is widely accepted that inflammatory molecules contribute to DNA damage. In this ancillary study, we investigated the influence of an encapsulated fruit and vegetable juice powder concentrate on peripheral blood lymphocytes (PBL) DNA damage. Using a double-blind, placebo-controlled approach, subjects were randomly assigned capsules containing placebo, or one of two formulations of the juice powder. Blood was drawn at baseline and after 60 days of capsule consumption. We found DNA damage in isolated PBL is suppressed after consumption of the encapsulated juice powder, and damage was correlated with the level of systemic inflammation. These data suggest a potential health benefit by consuming the juice concentrate capsules through their ability to suppress DNA damage as measured in surrogate tissues (PBL).

A hexane fraction of American ginseng suppresses mouse colitis and associated colon cancer: anti-inflammatory and proapoptotic mechanisms

Ulcerative colitis is a chronic inflammatory condition associated with a high colon cancer risk. We have previously reported that American ginseng extract significantly reduced the inflammatory parameters of chemically induced colitis. The aim of this study was to further delineate the components of American ginseng that suppress colitis and prevent colon cancer. Among five different fractions of American ginseng (butanol, hexane, ethylacetate, dichloromethane, and water), a hexane fraction has particularly potent antioxidant and proapoptotic properties. The effects of this fraction were shown in a mouse macrophage cell line (ANA-1 cells), in a human lymphoblastoid cell line (TK6), and in an ex vivo model (CD4(+)/CD25(-) primary effector T cells). A key in vivo finding was that compared with the whole American ginseng extract, the hexane fraction of American ginseng was more potent in treating colitis in a dextran sodium sulfate (DSS) mouse model, as well as suppressing azoxymethane/DSS-induced colon cancer. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling of inflammatory cells within the colonic mesenteric lymph nodes was elevated in mice consuming DSS + the hexane fraction of American ginseng. Results are consistent with our in vitro data and with the hypothesis that the hexane fraction of American ginseng has anti-inflammatory properties and drives inflammatory cell apoptosis in vivo, providing a mechanism by which this fraction protects from colitis in this DSS mouse model. This study moves us closer to understanding the molecular components of American ginseng that suppress colitis and prevent colon cancer associated with colitis.

The development of N-α-(2-carboxyl)benzoyl-N(5)-(2-fluoro-1-iminoethyl)-l-ornithine amide (o-F-amidine) and N-α-(2-carboxyl)benzoyl-N(5)-(2-chloro-1-iminoethyl)-l-ornithine amide (o-Cl-amidine) as second generation protein arginine deiminase (PAD) inhibitors

Protein arginine deiminase (PAD) activity is upregulated in a number of human diseases, including rheumatoid arthritis, ulcerative colitis, and cancer. These enzymes, there are five in humans (PADs 1-4 and 6), regulate gene transcription, cellular differentiation, and the innate immune response. Building on our successful generation of F- and Cl-amidine, which irreversibly inhibit all of the PADs, a structure-activity relationship was performed to develop second generation compounds with improved potency and selectivity. Incorporation of a carboxylate ortho to the backbone amide resulted in the identification of N-α-(2-carboxyl)benzoyl-N(5)-(2-fluoro-1-iminoethyl)-l-ornithine amide (o-F-amidine) and N-α-(2-carboxyl)benzoyl-N(5)-(2-chloro-1-iminoethyl)-l-ornithine amide (o-Cl-amidine), as PAD inactivators with improved potency (up to 65-fold) and selectivity (up to 25-fold). Relative to F- and Cl-amidine, the compounds also show enhanced potency in cellulo. As such, these compounds will be versatile chemical probes of PAD function.

Suppression of colitis in mice by Cl-amidine: a novel peptidylarginine deiminase inhibitor

Inflammatory bowel diseases (IBDs), mainly Crohn's disease and ulcerative colitis, are dynamic, chronic inflammatory conditions that are associated with an increased colon cancer risk. Inflammatory cell apoptosis is a key mechanism for regulating IBD. Peptidylarginine deiminases (PADs) catalyze the posttranslational conversion of peptidylarginine to peptidylcitrulline in a calcium-dependent, irreversible reaction and mediate the effects of proinflammatory cytokines. Because PAD levels are elevated in mouse and human colitis, we hypothesized that a novel small-molecule inhibitor of the PADs, i.e., chloramidine (Cl-amidine), could suppress colitis in a dextran sulfate sodium mouse model. Results are consistent with this hypothesis, as demonstrated by the finding that Cl-amidine treatment, both prophylactic and after the onset of disease, reduced the clinical signs and symptoms of colitis, without any indication of toxic side effects. Interestingly, Cl-amidine drives apoptosis of inflammatory cells in vitro and in vivo, providing a mechanism by which Cl-amidine suppresses colitis. In total, these data help validate the PADs as therapeutic targets for the treatment of IBD and further suggest Cl-amidine as a candidate therapy for this disease.

Abstract 4616: A hexane extract of American ginseng suppresses mouse colitis

Ulcerative colitis (UC) is a dynamic, idiopathic, chronic inflammatory condition associated with a high colon cancer risk. We have previously shown that American Ginseng (AG) extract prevents and treats colitis. The aim of this study was to better understand the components of American ginseng that suppress colitis. In this study we show that among five different fractions of AG (Butanol, Hexane, Ethylacetate, Dicholoromethane and Water), the Hexane fraction of American ginseng (HAG) has the most effective anti-oxidation and pro-apoptotic effect. This effect of HAG was shown in a mouse macrophage cell line (ANA-1 cells) and in an ex-vivo model (activated primary effector T cells, CD4+/CD25- T cells). Importantly, compared with the entire AG extract, the HAG was more potent in treating colitis in a dextran sulfate sodium (DSS) mouse model. Results from this study move us closer to understanding the molecular components of AG that suppress colitis, and perhaps prevent colon cancer associated with colitis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4616. doi:10.1158/1538-7445.AM2011-4616

Suppression of colitis-driven colon cancer in mice by a novel small molecule inhibitor of sphingosine kinase

Sphingolipid metabolism is driven by inflammatory cytokines. These cascade of events include the activation of sphingosine kinase (SK), and subsequent production of the mitogenic and proinflammatory lipid sphingosine 1-phosphate (S1P). Overall, S1P is one of the crucial components in inflammation, making SK an excellent target for the development of new anti-inflammatory drugs. We have recently shown that SK inhibitors suppress colitis and hypothesize here that the novel SK inhibitor, ABC294640, prevents the development of colon cancer. In an azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model, there was a dose-dependent decrease in tumor incidence with SK inhibitor treatment. The tumor incidence (number of animals with tumors per group) in the vehicle, ABC294640 (20 mg/kg) and ABC294640 (50 mg/kg) groups were 80, 40 and 30%, respectively. Tumor multiplicity (number of tumors per animal) also decreased from 2.1 ± 0.23 tumors per animal in the AOM + DSS + vehicle group to 1.2 ± 0 tumors per animal in the AOM + DSS + ABC294640 (20 mg/kg) and to 0.8 ± 0.4 tumors per animal in the AOM + DSS + ABC294640 (50 mg/kg) group. Importantly, with ABC294640, there were no observed toxic side effects. To explore mechanisms, we isolated cells from the colon (CD45-, representing primarily colon epithelial cells) and (CD45+, representing primarily colon inflammatory cells) then measured known targets of SK that control cell survival. Results are consistent with the hypothesis that the inhibition of SK activity by our novel SK inhibitor modulates key pathways involved in cell survival and may be a viable treatment strategy for the chemoprevention colitis-driven colon cancer.

An essential role of Nrf2 in American ginseng-mediated anti-oxidative actions in cardiomyocytes

AIM OF THE STUDY

Ginseng has been used as a folk medicine for thousands of years in Asia, and has become a popular herbal medicine world-wide. Recent studies have revealed that ginseng, including American ginseng, exerts antioxidant effects in the cardiovascular system; however, the underlying mechanisms are not fully understood. Thus, we investigated role of Nrf2, a master transcription factor of endogenous anti-oxidative defense systems, in the regulation of American ginseng-mediated anti-oxidative actions in cardiomyocytes.

MATERIALS AND METHODS

A standardized crude extract of American ginseng was supplied by the National Research Council of Canada, Institute for National Measurement Standards. H9C2 cells, a rat cardiomyocyte cell line, were exposed to angiotensin II (Ang II) or tumor necrosis factor alpha (TNFalpha) to induce oxidative stress that was examined by measuring formation of reactive oxygen and nitrogen species. Oxidative stress-induced cell death was induced by exogenous addition of hydrogen peroxide (H(2)O(2)). Proteins were measured by Western blot and mRNA expression was determined by quantitative real time PCR. Nrf2-driven transcriptional activity was assessed by antioxidant response element (ARE)-luciferase reporter assay. Direct Nrf2 binding to its target gene promoters was determined by chromatin immunoprecipitation assay. Adenoviral over-expression of Nrf2 shRNA was utilized to knock down Nrf2 in H9C2 cells. Immunochemical staining was applied for Nrf2 expression in the heart.

RESULTS

American ginseng induced dramatic increases in Nrf2 protein expression, Nrf2 nuclear translocation, Nrf2 transcriptional activity, direct Nrf2 binding to its target gene promoters, and expression of a group of anti-oxidative genes driven by Nrf2 in H9C2 cells. In addition, American ginseng inhibited Ang II- or TNFalpha-induced free radical formation and H(2)O(2)-induced cell death in H9C2 cells over-expressed with control shRNA but not in the cells over-expressed with Nrf2 shRNA. Finally, oral administration of American ginseng markedly increased Nrf2 activity in murine hearts.

CONCLUSION

These results demonstrate that American ginseng suppresses oxidative stress and oxidative stress-induced cell death in cardiomyocytes through activating the Nrf2 pathway, thereby providing cardioprotection against pathological cardiac remodeling.

Abstract 1152: A novel, practical method for improving the sensitivity and reproducibility of immunodetection

The sedentary nature of standard immune-detection techniques on a slide (e.g. immunohistochemistry, immunocytochemistry, and/or immunofluorescence) leads to the potential for tissue drying, and antibody pooling, ultimately resulting in uneven and inconsistent staining which can yield false negative or under readings. We therefore hypothesized that if we could provide motion in the antibody fluid while submerging the tissue laden slide, we could prevent such disadvantages. Here, we present data indicating that rocking such slides in an antibody bath leads to extremely even staining, highly reproducible results and greatly enhanced sensitivity. We found that for both nuclear and anti-nuclear antibodies, reaction sensitivity was increased 1000X to 1,000,000X over best practice with standard immune detection techniques. The immunodetection scores for p-P53/Serine 15, Ki-67 and Hsp 70 as well as experiment photographs comparing the sedentary to dynamic methods results are presented. References are also given.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1152.

Resveratrol suppresses colitis and colon cancer associated with colitis

Resveratrol is a naturally occurring polyphenol that exhibits pleiotropic health beneficial effects, including anti-inflammatory, cardio-protective, and cancer-protective activities. It is recognized as one of the more promising natural molecules in the prevention and treatment of chronic inflammatory and autoimmune disorders. Ulcerative colitis is an idiopathic, chronic inflammatory disease of the colon associated with a high colon cancer risk. Here, we used a dextran sulfate sodium (DSS) mouse model of colitis, which resembles human ulcerative colitis pathology. Resveratrol mixed in food ameliorates DSS-induced colitis in mice in a dose-dependent manner. Resveratrol significantly improves inflammation score, downregulates the percentage of neutrophils in the mesenteric lymph nodes and lamina propria, and modulates CD3(+) T cells that express tumor necrosis factor-alpha and IFN-gamma. Markers of inflammation and inflammatory stress (p53 and p53-phospho-Ser(15)) are also downregulated by resveratrol. Because chronic colitis drives colon cancer risk, we carried out experiments to determine the chemopreventive properties of resveratrol. Tumor incidence is reduced from 80% in mice treated with azoxymethane (AOM) + DSS to 20% in mice treated with AOM + DSS + resveratrol (300 ppm). Tumor multiplicity also decreased with resveratrol treatment. AOM + DSS-treated mice had 2.4 +/- 0.7 tumors per animal compared with AOM + DSS + 300 ppm resveratrol, which had 0.2 +/- 0.13 tumors per animal. The current study indicates that resveratrol is a useful, nontoxic complementary and alternative strategy to abate colitis and potentially colon cancer associated with colitis.

American ginseng suppresses colitis through p53-mediated apoptosis of inflammatory cells

Ulcerative colitis is a dynamic, chronic inflammatory condition associated with an increased colon cancer risk. Inflammatory cell apoptosis is a key mechanism regulating ulcerative colitis. American ginseng (AG) is a putative antioxidant that can suppress hyperactive immune cells. We have recently shown that AG can prevent and treat mouse colitis. Because p53 levels are elevated in inflammatory cells in both mouse and human colitis, we tested the hypothesis that AG protects from colitis by driving inflammatory cell apoptosis through a p53 mechanism. We used isogenic p53(+/+) and p53(-/-) inflammatory cell lines as well as primary CD4(+)/CD25(-) effector T cells from p53(+/+) and p53(-/-) mice to show that AG drives apoptosis in a p53-dependent manner. Moreover, we used a dextran sulfate sodium (DSS) model of colitis in C57BL/6 p53(+/+) and p53(-/-) mice to test whether the protective effect of AG against colitis is p53 dependent. Data indicate that AG induces apoptosis in p53(+/+) but not in isogenic p53(-/-) cells in vitro. In vivo, C57BL/6 p53(+/+) mice are responsive to the protective effects of AG against DSS-induced colitis, whereas AG fails to protect from colitis in p53(-/-) mice. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling of inflammatory cells within the colonic mesenteric lymph nodes is elevated in p53(+/+) mice consuming DSS + AG but not in p53(-/-) mice consuming DSS + AG. Results are consistent with our in vitro data and with the hypothesis that AG drives inflammatory cell apoptosis in vivo, providing a mechanism by which AG protects from colitis in this DSS mouse model.

Differential effects of reactive nitrogen species on DNA base excision repair initiated by the alkyladenine DNA glycosylase

Chronic generation of reactive nitrogen species (RNS) can cause DNA damage and may also directly modify DNA repair proteins. RNS-modified DNA is repaired predominantly by the base excision repair (BER) pathway, which includes the alkyladenine DNA glycosylase (AAG). The AAG active site contains several tyrosines and cysteines that are potential sites for modification by RNS. In vitro, we demonstrate that RNS differentially alter AAG activity depending on the site and type of modification. Nitration of tyrosine 162 impaired 1,N(6)-ethenoadenine (epsilonA)-excision activity, whereas nitrosation of cysteine 167 increased epsilonA excision. To understand the effects of RNS on BER in vivo, we examined intestinal adenomas for levels of inducible nitric oxide synthase (iNOS) and AAG. A striking correlation between AAG and iNOS expression was observed (r = 0.76, P = 0.00002). Interestingly, there was no correlation between changes in AAG levels and enzymatic activity. We found AAG to be nitrated in human adenomas, suggesting that this RNS modification is relevant in the human disease. Expression of key downstream components of BER, apurinic/apyrimidinic endonuclease 1 (APE1) and DNA polymerase beta (POLbeta), was also examined. POLbeta protein was increased in nearly all adenomas compared with adjacent non-tumor tissues, whereas APE1 expression was only increased in approximately half of the adenomas and also was relocalized to the cytoplasm in adenomas. Collectively, the results suggest that BER is dysregulated in colon adenomas. RNS-induced posttranslational modification of AAG is one mechanism of BER dysregulation, and the type of modification may define the role of AAG during carcinogenesis.

Resveratrol (trans-3,5,4'-trihydroxystilbene) induces silent mating type information regulation-1 and down-regulates nuclear transcription factor-kappaB activation to abrogate dextran sulfate sodium-induced colitis

Inflammatory bowel disease is a chronic, relapsing, and tissue-destructive disease. Resveratrol (3,4,5-trihydroxy-trans-stilbene), a naturally occurring polyphenol that exhibits beneficial pleiotropic health effects, is recognized as one of the most promising natural molecules in the prevention and treatment of chronic inflammatory disease and autoimmune disorders. In the present study, we investigated the effect of resveratrol on dextran sodium sulfate (DSS)-induced colitis in mice and found that it effectively attenuated overall clinical scores as well as various pathological markers of colitis. Resveratrol reversed the colitis-associated decrease in body weight and increased levels of serum amyloid A, tumor necrosis factor-alpha, interleukin (IL-6), and IL-1beta. After resveratrol treatment, the percentage of CD4(+) T cells in mesenteric lymph nodes (MLN) of colitis mice was restored to normal levels, and there was a decrease in these cells in the colon lamina propria (LP). Likewise, the percentages of macrophages in MLN and the LP of mice with colitis were decreased after resveratrol treatment. Resveratrol also suppressed cyclooxygenase-2 (COX-2) expression induced in DSS-exposed mice. Colitis was associated with a decrease in silent mating type information regulation-1 (SIRT1) gene expression and an increase in p-inhibitory kappaB expression and nuclear transcription factor-kappaB (NF-kappaB) activation. Resveratrol treatment of mice with colitis significantly reversed these changes. This study demonstrates for the first time that SIRT1 is involved in colitis, functioning as an inverse regulator of NF-kappaB activation and inflammation. Furthermore, our results indicate that resveratrol may protect against colitis through up-regulation of SIRT1 in immune cells in the colon.

Circadian disruption, Per3, and human cytokine secretion

Circadian disruption has been linked with inflammation, an established cancer risk factor. Per3 clock gene polymorphisms have also been associated with circadian disruption and with increased cancer risk. Patients completed a questionnaire and provided a blood sample prior to undergoing a colonoscopy (n = 70). Adjusted mean serum cytokine concentrations (IL-6, TNF-alpha, gamma-INF, IL-1ra, IL-1-beta, VEGF) were compared among patients with high and low scores for fatigue (Multidimensional Fatigue Inventory), depressive symptoms (Beck Depression Inventory II), or sleep disruption (Pittsburgh Sleep Quality Index), or among patients with different Per3 clock gene variants. Poor sleep was associated with elevated VEGF, and fatigue-related reduced activity was associated with elevated TNF-alpha concentrations. Participants with the 4/5 or 5/5 Per3 variable tandem repeat sequence had elevated IL-6 concentrations compared to those with the 4/4 genotype. Biological processes linking circadian disruption with cancer remain to be elucidated. Increased inflammatory cytokine secretion may play a role.

American ginseng preferentially suppresses STAT/iNOS signaling in activated macrophages

AIM OF THE STUDY

Ginseng has been used as general tonic for thousands of years in Asia and becomes a popular herbal medicine all over the world. However, the cellular and molecular mechanisms underlying its benefit effects are less explored. Thus, we investigated the effect of a crude extract from Panax quinquefolius (American ginseng) on suppression of pro-inflammatory responses in macrophages with a focus on signal transducer and activator of transcription (STAT) signaling.

MATERIALS AND METHODS

The crude extract of American ginseng that was supplied by the National Research Council of Canada, Institute for National Measurement Standards (NRCC-INMS) was freshly solvated in Dulbecco's Modified Eagle Medium (DMEM) prior to each experiment. RAW264.7 cells, a murine macrophage cell line, were exposed to lipopolysaccharide (LPS) to induce inflammatory responses such as expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). Proteins were measured by Western blot and mRNA expression was determined by quantitative real-time PCR (Q-PCR). Activator protein 1 (AP-1)-, nuclear factor-kappaB (NF-kappaB)- and STAT-mediated transcriptional activities were investigated using luciferase reporter constructs.

RESULTS

American ginseng inhibited LPS-induced iNOS expression; however, it did not affect LPS-induced COX2 expression. While American ginseng had no impact on LPS-induced activation of AP-1 or NF-kappaB pathways, it dramatically inhibited LPS-induced activation of STAT signaling. Moreover, American ginseng and AG490, an inhibitor of STAT cascade, synergistically suppressed the LPS-induced iNOS expression.

CONCLUSION

American ginseng selectively inhibits the expression of iNOS via suppression of STAT cascade but not NF-kappaB and AP-1 pathways in inflamed macrophages. Such a preferential suppression of STAT/iNOS cascade by American ginseng might have therapeutic potential for inflammatory diseases with over-activation of iNOS.

Gastrointestinal hyperplasia with altered expression of DNA polymerase beta

Background

Altered expression of DNA polymerase β (Pol β) has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol β over-expression has not yet been evaluated in a mouse model.

Methodology/Principal Findings

We have recently developed a novel transgenic mouse model that over-expresses Pol β. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol β over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol β expression. We observed elevated expression of Pol β in stomach adenomas and thyroid follicular carcinomas, but reduced Pol β expression in esophageal adenocarcinomas and squamous carcinomas.

Conclusions/Significance

These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation.

Nitric oxide is a key component in inflammation-accelerated tumorigenesis

Nitric oxide (NO(*)), an important signaling molecule and a component of inflammatory response, is involved in tumorigenesis. However, the quantity of NO(*) and the cellular microenvironment influences the role of NO(*) in tumor development. We used a genetic strategy to test the hypothesis that an inflammatory microenvironment with an enhanced level of NO(*) accelerates spontaneous tumor development. C. parvum-induced inflammation and increased NO(*) synthase-2 (NOS2) expression coincided with accelerated spontaneous tumor development, mostly lymphomas, in p53-/-NOS2+/+ C57BL6 mice when compared with the controls (P = 0.001). However, p53-/-NOS2-/- mice did not show any difference in tumor latency between C. parvum-treated and control groups. In C. parvum-treated p53-/-NOS2+/+ mice, tumor development was preceded by a higher expression of NOS2 and phosphorylated Akt-Ser(473) (pAkt-Ser473) in spleen, increased cell proliferation measured by Ki-67 IHC in spleen and thymus, and a lower apoptotic index and CD95-L expression in spleen and thymus. C. parvum-treated p53-/-NOS2+/+ mice showed an increase in the number of Foxp3(+) T-reg cells, dendritic cells (DC), as well as increased CD80(+), CD86(+), CD40(+), and CD83(+) on DC in the spleen. Regulatory T-cells (T-reg) and the maturation of DC may modulate tumorigenesis. An increase in the FoxP3(+)T-reg cells in C. parvum-treated p53-/-NOS2+/+ mice indicates a role of NO(*) in the regulation of T-reg cells that may contribute to a protumor shift of the immune environment favoring an accelerated tumor development. These data provide genetic and mechanistic evidence that an inflammatory microenvironment and an increased level of NO(*) can accelerate tumor development.

American ginseng suppresses inflammation and DNA damage associated with mouse colitis

Ulcerative colitis (UC) is a dynamic, idiopathic, chronic inflammatory condition associated with a high colon cancer risk. American ginseng has antioxidant properties and targets many of the players in inflammation. The aim of this study was to test whether American ginseng extract prevents and treats colitis. Colitis in mice was induced by the presence of 1% dextran sulfate sodium (DSS) in the drinking water or by 1% oxazolone rectally. American ginseng extract was mixed in the chow at levels consistent with that currently consumed by humans as a supplement (75 p.p.m., equivalent to 58 mg daily). To test prevention of colitis, American ginseng extract was given prior to colitis induction. To test treatment of colitis, American ginseng extract was given after the onset of colitis. In vitro studies were performed to examine mechanisms. Results indicate that American ginseng extract not only prevents but it also treats colitis. Inducible nitric oxide synthase and cyclooxygenase-2 (markers of inflammation) and p53 (induced by inflammatory stress) are also downregulated by American ginseng. Mucosal and DNA damage associated with colitis is at least in part a result of an oxidative burst from overactive leukocytes. We therefore tested the hypothesis that American ginseng extract can inhibit leukocyte activation and subsequent epithelial cell DNA damage in vitro and in vivo. Results are consistent with this hypothesis. The use of American ginseng extract represents a novel therapeutic approach for the prevention and treatment of UC.

Nitric oxide as a target of complementary and alternative medicines to prevent and treat inflammation and cancer

Nitric oxide (NO) and associated reactive nitrogen species (RNS) are involved in many physiological functions. There has been an ongoing debate to whether RNS can inhibit or perpetuate chronic inflammation and associated carcinogenesis. Although the final outcome depends on the genetic make-up of its target, the surrounding microenvironment, the activity and localization of nitric oxide synthase (NOS) isoforms, and overall levels of NO/RNS, evidence is accumulating that in general, RNS drive inflammation and cancers associated with inflammation. To this end, many complementary and alternative medicines (CAMs) that work in chemoprevention associated with chronic inflammation, are inhibitors of excessive NO observed in inflammatory conditions. Here, we review recent literature outlining a role of NO/RNS in chronic inflammation and cancer, and point toward NO as one of several targets for the success of CAMs in treating chronic inflammation and cancer associated with this inflammation.

Ginkgo biloba extract EGb 761 has anti-inflammatory properties and ameliorates colitis in mice by driving effector T cell apoptosis

Ulcerative colitis is a dynamic, chronic inflammatory condition of the colon associated with an increased colon cancer risk. Ginkgo biloba is a putative antioxidant and has been used for thousands of years to treat a variety of ailments. The aim of this study was to test whether the standardized G.biloba extract, EGb 761, is an antioxidant that can be used to prevent and treat colitis in mice. Here, we show that EGb 761 suppresses the activation of macrophages and can be used to both prevent and treat mouse colitis. Markers of inflammation (iNOS, Cox-2 and tumor necrosis factor-alpha) and inflammatory stress (p53 and p53-phospho-serine 15) are also downregulated by EGb 761. Furthermore, we show that EGb 761 reduces the numbers of CD4+/CD25-/Foxp3- effector T cells in the colon. Interestingly, EGb 761 drives CD4+ effector T cell apoptosis in vitro and in vivo, providing a mechanistic explanation to the reduction in numbers of this cell type in the colon. This current study is in agreement with previous studies supporting a use of EGb 761 as a complementary and alternative strategy to abate colitis and associated colon cancer.

Attenuation of experimental autoimmune hepatitis by exogenous and endogenous cannabinoids: involvement of regulatory T cells

Immune-mediated liver diseases including autoimmune and viral hepatitis are a major health problem worldwide. Natural cannabinoids such as Delta(9)-tetrahydrocannabinol (THC) effectively modulate immune cell function, and they have shown therapeutic potential in treating inflammatory diseases. We investigated the effects of THC in a murine model of concanavalin A (ConA)-induced hepatitis. Intraperitoneal administration of THC after ConA challenge inhibited hepatitis as shown by significant decrease in liver enzymes and reduced liver tissue injury. Furthermore, THC treatment resulted in significant suppression of crucial inflammatory cytokines in ConA-induced hepatitis. It is noteworthy that THC treatment in ConA-injected mice led to significant increase in absolute number of Forkhead helix transcription factor p3+ T regulatory cells in liver. We were surprised to find that select cannabinoid receptor (CB1 or CB2) agonists were not able to block hepatitis either independently or in combination. However, CB1/CB2 mixed agonists were able to efficiently attenuate hepatitis similar to THC. The modulatory effect of THC in ConA-induced hepatitis was reversed by both CB1 and CB2 antagonists. We also observed that endogenous cannabinoid anandamide was able to reduce hepatitis by suppressing cytokine levels. In addition, deficiency or inhibition of endocannabinoid hydrolyzing enzyme fatty acid amide hydrolase (FAAH), which leads to increased levels of endogenous cannabinoids, resulted in decreased liver injury upon ConA challenge. Our data demonstrate that targeting cannabinoid receptors using exogenous or endogenous cannabinoids and use of FAAH inhibitors may constitute novel therapeutic modalities to treat immune-mediated liver inflammation.