The interaction of a high-fat diet and regular moderate intensity exercise on intestinal polyp development in Apc Min/+ mice

The Influence of Exercise on Cancer Risk, the Tumor Microenvironment and the Treatment of Cancer

There are several modifiable factors that can be targeted to prevent and manage the occurrence and progression of cancer, and maintaining adequate exercise is a crucial one. Regular physical exercise has been shown to be a beneficial strategy in preventing cancer, potentially amplifying the effectiveness of established cancer therapies, alleviating certain cancer-related symptoms, and possibly mitigating side effects resulting from treatment. Nevertheless, the exact mechanisms by which exercise affects tumors, especially its impact on the tumor microenvironment (TME), remain uncertain. This review aims to present an overview of the beneficial effects of exercise in the context of cancer management, followed by a summary of the exercise parameters, especially exercise intensity, that need to be considered when prescribing exercise for cancer patients. Finally, we discuss the influence of exercise on the TME, including its effects on crucial immune cells (e.g., T cells, macrophages, neutrophils, natural killer cells, myeloid-derived suppressor cells, B cells), intratumor angiogenesis, and cancer metabolism. This comprehensive review provides up-to-date scientific evidence on the effects of exercise training on cancer and offers guidance to clinicians for the development of safe and feasible exercise training programs for cancer patients in clinical practice.

Exercise and colorectal cancer: prevention and molecular mechanisms

Exercise and physical activity have been shown to be strongly associated with a decreased incidence rate of various chronic diseases especially numerous human malignancies. A huge number of clinical trials and meta-analysis have demonstrated that exercise is significantly effective in lowering the risk of colorectal cancer. In addition, it is suggested as an effective therapeutic modality against this cancer type. Therefore, in this review, we will review comprehensibly the effects of exercise in preventing, treating, and alleviating the adverse effects of conventional therapeutic options in colorectal cancer. Moreover, the possible mechanisms underlying the positive effects of exercise and physical activity in colorectal cancer, including regulation of inflammation, apoptosis, growth factor axis, immunity, epigenetic, etc. will be also discussed.

Exercise is an effective post-treatment management program in colorectal cancer survivals

Exercise improves muscle strength, cardiorespiratory fitness, emotional distress, physical activity, fatigue, and sleep quality in colorectal patients undergoing chemotherapy

Targeting and modulating insulin-like growth factor (IGF) system, inflammation, apoptosis, immunity, epigenetic, Leptin and Ghrelin, and signaling pathways are major underlying mechanisms for preventive effects of exercise in colorectal cancer

Exercise suppresses tumor growth independent of high fat food intake and associated immune dysfunction

Epidemiological data suggest that exercise training protects from cancer independent of BMI. Here, we aimed to elucidate mechanisms involved in voluntary wheel running-dependent control of tumor growth across chow and high-fat diets. Access to running wheels decreased tumor growth in B16F10 tumor-bearing on chow (− 50%) or high-fat diets (− 75%, p < 0.001), however, tumor growth was augmented in high-fat fed mice (+ 53%, p < 0.001). Tumor growth correlated with serum glucose (p < 0.01), leptin (p < 0.01), and ghrelin levels (p < 0.01), but not with serum insulin levels. Voluntary wheel running increased immune recognition of tumors as determined by microarray analysis and gene expression analysis of markers of macrophages, NK and T cells, but the induction of markers of macrophages and NK cells was attenuated with high-fat feeding. Moreover, we found that the regulator of innate immunity, ZBP1, was induced by wheel running, attenuated by high-fat feeding and associated with innate immune recognition in the B16F10 tumors. We observed no effects of ZBP1 on cell cycle arrest, or exercise-regulated necrosis in the tumors of running mice. Taken together, our data support epidemiological findings showing that exercise suppresses tumor growth independent of BMI, however, our data suggest that high-fat feeding attenuates exercise-mediated immune recognition of tumors.

OMICS Applications for Medicinal Plants in Gastrointestinal Cancers: Current Advancements and Future Perspectives

Gastrointestinal cancers refer to a group of deadly malignancies of the gastrointestinal tract and organs of the digestive system. Over the past decades, considerable amounts of medicinal plants have exhibited potent anticancer effects on different types of gastrointestinal cancers. OMICS, systems biology approaches covering genomics, transcriptomics, proteomics and metabolomics, are broadly applied to comprehensively reflect the molecular profiles in mechanistic studies of medicinal plants. Single- and multi-OMICS approaches facilitate the unravelling of signalling interaction networks and key molecular targets of medicinal plants with anti-gastrointestinal cancer potential. Hence, this review summarizes the applications of various OMICS and advanced bioinformatics approaches in examining therapeutic targets, signalling pathways, and the tumour microenvironment in response to anticancer medicinal plants. Advances and prospects in this field are also discussed.

Dietary interventions as regulators of stem cell behavior in homeostasis and disease

Stem cells maintain tissues by balancing self-renewal with differentiation. A stem cell's local microenvironment, or niche, informs stem cell behavior and receives inputs at multiple levels. Increasingly, it is becoming clear that the overall metabolic status of an organism or metabolites themselves can function as integral members of the niche to alter stem cell fate. Macroscopic dietary interventions such as caloric restriction, the ketogenic diet, and a high-fat diet systemically alter an organism's metabolic state in different ways. Intriguingly, however, they all converge on a propensity to enhance self-renewal. Here, we highlight our current knowledge on how dietary changes feed into stem cell behavior across a wide variety of tissues and illuminate possible explanations for why diverse interventions can result in similar stem cell phenotypes. In so doing, we hope to inspire new avenues of inquiry into the importance of metabolism in stem cell homeostasis and disease.

Worldwide flavor enhancer monosodium glutamate combined with high lipid diet provokes metabolic alterations and systemic anomalies: An overview

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Flavor enhancing high lipid diet acts as silent killer.

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Monosodium glutamate mixed with high lipid diet alters redox-status.

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Monosodium glutamate mixed with high lipid diet induces systemic anomalies.

In this fast-food era, people depend on ready-made foods and engage in minimal physical activities that ultimately change their food habits. Majorities of such foods have harmful effects on human health due to higher percentages of saturated fatty acids, trans-fatty acids, and hydrogenated fats in the form of high lipid diet (HLD). Moreover, food manufacturers add monosodium glutamate (MSG) to enhance the taste and palatability of the HLD. Both MSG and HLD induce the generation of reactive oxygen species (ROS) and thereby alter the redox-homeostasis to cause systemic damage. However, MSG mixed HLD (MH) consumption leads to dyslipidemia, silently develops non-alcoholic fatty liver disease followed by metabolic alterations and systemic anomalies, even malignancies, via modulating different signaling pathways. This comprehensive review formulates health care strategies to create global awareness about the harmful impact of MH on the human body and recommends the daily consumption of more natural foods rich in antioxidants instead of toxic ingredients to counterbalance the MH-induced systemic anomalies.

Analysis of mutations in tumor and normal adjacent tissue via fluorescence detection

Inflammation is a major risk factor for many types of cancer, including colorectal. There are two fundamentally different mechanisms by which inflammation can contribute to carcinogenesis. First, reactive oxygen and nitrogen species (RONS) can damage DNA to cause mutations that initiate cancer. Second, inflammatory cytokines and chemokines promote proliferation, migration, and invasion. Although it is known that inflammation-associated RONS can be mutagenic, the extent to which they induce mutations in intestinal stem cells has been little explored. Furthermore, it is now widely accepted that cancer is caused by successive rounds of clonal expansion with associated de novo mutations that further promote tumor development. As such, we aimed to understand the extent to which inflammation promotes clonal expansion in normal and tumor tissue. Using an engineered mouse model that is prone to cancer and within which mutant cells fluoresce, here we have explored the impact of inflammation on de novo mutagenesis and clonal expansion in normal and tumor tissue. While inflammation is strongly associated with susceptibility to cancer and a concomitant increase in the overall proportion of mutant cells in the tissue, we did not observe an increase in mutations in normal adjacent tissue. These results are consistent with opportunities for de novo mutations and clonal expansion during tumor growth, and they suggest protective mechanisms that suppress the risk of inflammation-induced accumulation of mutant cells in normal tissue.

What is the gut feeling telling us about physical activity in colorectal carcinogenesis?

In the last decades, more efforts are focused on the prevention and treatment of malignant diseases, given the increase in all cancers incidence A lifestyle change, including healthy eating habits and regular physical activity, has significantly impacted colorectal cancer prevention. The effect of dose-dependent physical activity on mortality and recurrence rates of colorectal carcinoma has been unequivocally demonstrated in observational studies. However, clear recommendations are not available on the frequency, duration, and intensity of exercise in patients with colorectal cancer due to the lack of evidence in randomized clinical trials. Regarding pathophysiological mechanisms, the most plausible explanation appears to be the influence of physical activity on reducing chronic inflammation and insulin resistance with a consequent positive effect on insulin growth factor 1 signaling pathways.

Clostridium butyricum, a butyrate-producing probiotic, inhibits intestinal tumor development through modulating Wnt signaling and gut microbiota

Gut microbiota dysbiosis is closely involved in intestinal carcinogenesis. A marked reduction in butyrate-producing bacteria has been observed in patients with colorectal cancer (CRC); nevertheless, the potential benefit of butyrate-producing bacteria against intestinal tumor development has not been fully investigated. We found that Clostridium butyricum (C. butyricum, one of the commonly used butyrate-producing bacteria in clinical settings) significantly inhibited high-fat diet (HFD)-induced intestinal tumor development in Apc^min/+ mice. Moreover, intestinal tumor cells treated with C. butyricum exhibited decreased proliferation and increased apoptosis. Additionally, C. butyricum suppressed the Wnt/β-catenin signaling pathway and modulated the gut microbiota composition, as demonstrated by decreases in some pathogenic bacteria and bile acid (BA)-biotransforming bacteria and increases in some beneficial bacteria, including short-chain fatty acid (SCFA)-producing bacteria. Accordingly, C. butyricum decreased the fecal secondary BA contents, increased the cecal SCFA quantities, and activated G-protein coupled receptors (GPRs), such as GPR43 and GPR109A. The anti-proliferative effect of C. butyricum was blunted by GPR43 gene silencing using small interfering RNA (siRNA). The analysis of clinical specimens revealed that the expression of GPR43 and GPR109A gradually decreased from human normal colonic tissue to adenoma to carcinoma. Together, our results show that C. butyricum can inhibit intestinal tumor development by modulating Wnt signaling and gut microbiota and thus suggest the potential efficacy of butyrate-producing bacteria against CRC.

PPARδ Mediates the Effect of Dietary Fat in Promoting Colorectal Cancer Metastasis

The nuclear hormone receptor peroxisome proliferator-activated receptor delta (PPARδ) is a ligand-dependent transcription factor involved in fatty acid metabolism, obesity, wound healing, inflammation, and cancer. Although PPARδ has been shown to promote intestinal adenoma formation and growth, the molecular mechanisms underlying the contribution of PPARδ to colorectal cancer remain unclear. Here, we demonstrate that activation of PPARδ induces expansion of colonic cancer stem cells (CSC) and promotes colorectal cancer liver metastasis by binding to the Nanog promoter and enhancing Nanog expression. Moreover, PPARδ mediated the effect of a high-fat diet in promoting liver metastasis and induction of colonic CSC expansion. Our findings uncover a novel role of dietary fats in colorectal cancer metastasis and reveal novel mechanisms underlying PPARδ-mediated induction of CSCs and those responsible for the contribution of dietary fats to colorectal cancer progression. These findings may provide a rationale for developing PPARδ antagonists to therapeutically target CSCs in colorectal cancer. SIGNIFICANCE: These findings show that PPARδ contributes to colorectal cancer metastasis by expanding the CSC population, indicating that antagonists that target PPARδ may be beneficial in treating colorectal cancer.

Effect of exercise on colorectal cancer prevention and treatment

In recent years, because of improved cancer screening, detection and treatment modalities, a rapid increase in the population of colorectal and other cancer survivors has been observed. The increasing population has justified the requirement of preventive strategies such as lifestyle modifications with regard to obesity, physical activity, diet and smoking. Physical activity may prevent approximately 15% of the colon cancers. Furthermore, several observational studies have demonstrated the efficacy and dose-dependent and anti-cancer effects of exercise on decreasing the mortality and risk of recurrence before and after the colorectal cancer (CRC) diagnosis. However, the required exercise dose, type and intensity are yet unclear. The results of randomised prospective studies are expected to determine the optimal amount, type and intensity of exercise and formulate the most appropriate exercise plan and guidelines, according to the requirements and comorbidities of the patients. In addition, recent studies have focused on the molecular and genetic mechanisms underlying the effect of physical activity on disease outcomes and recurrence rates. This review aimed to investigate the effects of physical activity and the biological basis of these effects in preventing the risk and recurrence of CRC and decreasing the hazards of cancer and cancer treatment.

Losartan and Vitamin D Inhibit Colonic Tumor Development in a Conditional Apc-Deleted Mouse Model of Sporadic Colon Cancer

Colorectal cancer is a leading cause of cancer deaths. The renin-angiotensin system (RAS) is upregulated in colorectal cancer, and epidemiologic studies suggest RAS inhibitors reduce cancer risk. Because vitamin D (VD) receptor negatively regulates renin, we examined anticancer efficacy of VD and losartan (L), an angiotensin receptor blocker. Control Apc^+/LoxP mice and tumor-forming Apc^+/LoxP Cdx2P-Cre mice were randomized to unsupplemented Western diet (UN), or diets supplemented with VD, L, or VD+L, the latter to assess additive or synergistic effects. At 6 months, mice were killed. Plasma Ca²⁺, 25(OH)D3, 1α, 25(OH)2D3, renin, and angiotensin II (Ang II) were quantified. Colonic transcripts were assessed by qPCR and proteins by immunostaining and blotting. Cancer incidence and tumor burden were significantly lower in Cre+ VD and Cre+ L, but not in the Cre+ VD+L group. In Apc^+/LoxP mice, VD increased plasma 1,25(OH)2D3 and colonic VDR. In Apc^+/LoxP-Cdx2P-Cre mice, plasma renin and Ang II, and colonic tumor AT1, AT2, and Cyp27B1 were increased and VDR downregulated. L increased, whereas VD decreased plasma renin and Ang II in Cre+ mice. VD or L inhibited tumor development, while exerting differential effects on plasma VD metabolites and RAS components. We speculate that AT1 is critical for tumor development, whereas RAS suppression plays a key role in VD chemoprevention. When combined with L, VD no longer increases active VD and colonic VDR in Cre- mice nor suppresses renin and Ang II in Cre+ mice, likely contributing to lack of chemopreventive efficacy of the combination.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Intestinal insulin/IGF1 signalling through FoxO1 regulates epithelial integrity and susceptibility to colon cancer

Obesity promotes the development of insulin resistance and increases the incidence of colitis-associated cancer (CAC), but whether a blunted insulin action specifically in intestinal epithelial cells (IECs) affects CAC is unknown. Here, we show that obesity impairs insulin sensitivity in IECs and that mice with IEC-specific inactivation of the insulin and IGF1 receptors exhibit enhanced CAC development as a consequence of impaired restoration of gut barrier function. Blunted insulin signalling retains the transcription factor FOXO1 in the nucleus to inhibit expression of Dsc3, thereby impairing desmosome formation and epithelial integrity. Both IEC-specific nuclear FoxO1ADA expression and IEC-specific Dsc3 inactivation recapitulate the impaired intestinal integrity and increased CAC burden. Spontaneous colonic tumour formation and compromised intestinal integrity are also observed upon IEC-specific coexpression of FoxO1ADA and a stable Myc variant, thus suggesting a molecular mechanism through which impaired insulin action and nuclear FOXO1 in IECs promotes CAC.

Effects of obesity and exercise on colon cancer induction and hematopoiesis in mice

Obesity-induced inflammation is associated with increased risk for colorectal cancer (CRC). The role of diet and exercise in modulating increased CRC risk in obesity and the potential role of altered hematopoiesis as a contributor to these effects remain unknown. The purpose of this study was to examine how weight loss induced during CRC induction with or without exercise alters CRC initiation and its relationship to altered hematopoiesis. Mice consumed either a control (CON) or a high-fat diet to induce obesity. All mice were then placed on the control diet during CRC induction with azoxymethane (AOM). Following AOM injection, mice originally on the high-fat diet were randomized into sedentary (HF-SED) or exercise trained (HF-EX) conditions. At euthanasia, body weight and fat mass were similar among all three groups ( P < 0.05). Compared with CON and HF-EX, HF-SED developed increased content of preneoplastic lesions ( P < 0.05), and HF-SED had significantly increased markers of colon inflammation compared with CON. Compared with both CON and HF-EX, HF-SED had decreased content of short-term hematopoietic stem cells and increased content of common myeloid progenitor cells (both P < 0.05). Similarly, HF-SED had increased bone marrow adiposity compared with CON and HF-EX ( P < 0.05), and proteomics analysis revealed an increased marker of bone marrow inflammation in HF-SED compared with CON and HF-EX. Our results suggest that the early removal of a high-fat diet reduces CRC incidence when combined with an exercise training intervention. This reduction in risk was related to lower colon inflammation with anti-inflammatory changes in hematopoiesis induced by exercise.

Obesity-Induced TNFα and IL-6 Signaling: The Missing Link between Obesity and Inflammation-Driven Liver and Colorectal Cancers

Obesity promotes the development of numerous cancers, such as liver and colorectal cancers, which is at least partly due to obesity-induced, chronic, low-grade inflammation. In particular, the recruitment and activation of immune cell subsets in the white adipose tissue systemically increase proinflammatory cytokines, such as tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). These proinflammatory cytokines not only impair insulin action in metabolic tissues, but also favor cancer development. Here, we review the current state of knowledge on how obesity affects inflammatory TNFα and IL-6 signaling in hepatocellular carcinoma and colorectal cancers.

Inflammatory Links Between High Fat Diets and Diseases

In recent years, chronic overnutrition, such as consumption of a high-fat diet (HFD), has been increasingly viewed as a significant modifiable risk factor for diseases such as diabetes and certain types of cancer. However, the mechanisms by which HFDs exert adverse effects on human health remains poorly understood. Here, this paper will review the recent scientific literature about HFD-induced inflammation and subsequent development of diseases and cancer, with an emphasis on mechanisms involved. Given the expanding global epidemic of excessive HFD intake, understanding the impacts of a HFD on these medical conditions, gaining great insights into possible underlying mechanisms, and developing effective therapeutic strategies are of great importance.

Nutritional Regulation of Intestinal Stem Cells

Dietary composition and calorie intake are major determinants of health and disease. Calorie restriction promotes metabolic changes that favor tissue regeneration and is arguably the most successful and best-conserved antiaging intervention. Obesity, in contrast, impairs tissue homeostasis and is a major risk factor for the development of diseases including cancer. Stem cells, the central mediators of tissue regeneration, integrate dietary and energy cues via nutrient-sensing pathways to maintain growth or respond to stress. We discuss emerging data on the effects of diet and nutrient-sensing pathways on intestinal stem cells, as well as their potential application in the development of regenerative and therapeutic interventions.

Short-term pyrrolidine dithiocarbamate administration attenuates cachexia-induced alterations to muscle and liver in ApcMin/+ mice

Cancer cachexia is a complex wasting condition characterized by chronic inflammation, disrupted energy metabolism, and severe muscle wasting. While evidence in pre-clinical cancer cachexia models have determined that different systemic inflammatory inhibitors can attenuate several characteristics of cachexia, there is a limited understanding of their effects after cachexia has developed, and whether short-term administration is sufficient to reverse cachexia-induced signaling in distinctive target tissues. Pyrrolidine dithiocarbamate (PDTC) is a thiol compound having anti-inflammatory and antioxidant properties which can inhibit STAT3 and nuclear factor κB (NF-κB) signaling in mice. This study examined the effect of short-term PDTC administration to ApcMin/+ mice on cachexia-induced disruption of skeletal muscle protein turnover and liver metabolic function. At 16 weeks of age ApcMin/+ mice initiating cachexia (7% BW loss) were administered PDTC (10mg/kg bw/d) for 2 weeks. Control ApcMin/+ mice continued to lose body weight during the treatment period, while mice receiving PDTC had no further body weight decrease. PDTC had no effect on either intestinal tumor burden or circulating IL-6. In muscle, PDTC rescued signaling disrupting protein turnover regulation. PDTC suppressed the cachexia induction of STAT3, increased mTORC1 signaling and protein synthesis, and suppressed the induction of Atrogin-1 protein expression. Related to cachectic liver metabolic function, PDTC treatment attenuated glycogen and lipid content depletion independent to the activation of STAT3 and mTORC1 signaling. Overall, these results demonstrate short-term PDTC treatment to cachectic mice attenuated cancer-induced disruptions to muscle and liver signaling, and these changes were independent to altered tumor burden and circulating IL-6.

Characterization of Colorectal Cancer Development in Apc (min/+) Mice

The Apc (min/+) mouse provides an excellent experimental model for studying genetic, environmental, and therapeutic aspects of intestinal neoplasia in humans. In this chapter, we will describe techniques for studying colon cancer development in Apc (min/+) mice on C57BL/6J (B6) background, focusing on the roles of environmental modifiers, including Dextran Sulfate Sodium (DSS), high fat diet, and bile acid supplementation in the context of experimental colorectal cancer. This chapter also includes protocols describing extraction and purification of DSS-contaminated RNA, as well as sampling, harvesting, and tissue processing. The common pathologic lesions encountered in these animals are described in detail.

Western diet enhances intestinal tumorigenesis in Min/+ mice, associating with mucosal metabolic and inflammatory stress and loss of Apc heterozygosity

Western-type diet (WD) is a risk factor for colorectal cancer, but the underlying mechanisms are poorly understood. We investigated the interaction of WD and heterozygous mutation in the Apc gene on adenoma formation and metabolic and immunological changes in the histologically normal intestinal mucosa of Apc^Min/+ (Min/+) mice. The diet used was high in saturated fat and low in calcium, vitamin D, fiber and folate. The number of adenomas was twofold higher in the WD mice compared to controls, but adenoma size, proliferation or apoptosis did not differ. The ratio of the Min to wild-type allele was higher in the WD mice, indicating accelerated loss of Apc heterozygosity (LOH). Densities of intraepithelial CD3ε⁺ T lymphocytes and of mucosal FoxP3⁺ regulatory T cells were higher in the WD mice, implying inflammatory changes. Western blot analyses from the mucosa of the WD mice showed suppressed activation of the ERK and AKT pathways and a tendency for reduced activation of the mTOR pathway as measured in phosphoS6/S6 levels. The expression of pyruvate dehydrogenase kinase 4 was up-regulated in both mRNA and protein levels. Gene expression analyses showed changes in oxidation/reduction, fatty acid and monosaccharide metabolic pathways, tissue organization, cell fate and regulation of apoptosis. Together, our results suggest that the high-risk Western diet primes the intestine to tumorigenesis through synergistic effects in energy metabolism, inflammation and oxidative stress, which culminate in the acceleration of LOH of the Apc gene.

Effects of propolis and gamma-cyclodextrin on intestinal neoplasia in normal weight and obese mice

Obesity is associated with colorectal cancer (CRC). This effect might be attributed to adipokine‐supported signaling. We have established that propolis suppresses survival signaling in CRC cells in vitro; therefore, we ascertained the ability of a propolis supplement to modulate intestinal neoplastic development in C57BL/6J‐ApcMin/+/J mice in the lean and obese state. To induce obesity, mice were fed with a Western diet containing 40% fat. Since the propolis supplement includes gamma‐cyclodextrin, the interventions included diets supplemented with or without gamma‐cyclodextrin. The animals were administered the following diets: (1) control diet, (2) control diet/gamma‐cyclodextrin, (3) control diet/propolis, (4) Western diet, (5) Western diet/gamma‐cyclodextrin, and (6) Western diet/propolis. Western diet, resulting in obesity, accelerated neoplastic progression, as evidenced by the larger size and higher grade dysplasia of the neoplasms. In the context of normal weight, gamma‐cyclodextrin and propolis affected neoplastic progression, as determined by the size of the lesions and their grade of dysplasia. A statistically significant decrease in the number of adenomas was detected in mice fed a control diet with the propolis supplement (61.8 ± 10.6 vs. 35.3 ± 7.6, P = 0.008). Although there was no significant difference in the polyp numbers between the six groups, the mice with the lowest number and size of adenomas were those fed a Western diet with gamma‐cyclodextrin. This unexpected outcome might be explained by the increased levels of apoptosis detected in the intestinal tissues of these obese mice. We posit that butyrate derived from the metabolism of gamma‐cyclodextrin may contribute to the decreased neoplastic burden in the context of obesity; however, future studies are required to address this possibility.

High-fat diet enhances stemness and tumorigenicity of intestinal progenitors

Little is known about how pro-obesity diets regulate tissue stem and progenitor cell function. Here we show that high-fat diet (HFD)-induced obesity augments the numbers and function of Lgr5(+) intestinal stem cells of the mammalian intestine. Mechanistically, a HFD induces a robust peroxisome proliferator-activated receptor delta (PPAR-δ) signature in intestinal stem cells and progenitor cells (non-intestinal stem cells), and pharmacological activation of PPAR-δ recapitulates the effects of a HFD on these cells. Like a HFD, ex vivo treatment of intestinal organoid cultures with fatty acid constituents of the HFD enhances the self-renewal potential of these organoid bodies in a PPAR-δ-dependent manner. Notably, HFD- and agonist-activated PPAR-δ signalling endow organoid-initiating capacity to progenitors, and enforced PPAR-δ signalling permits these progenitors to form in vivo tumours after loss of the tumour suppressor Apc. These findings highlight how diet-modulated PPAR-δ activation alters not only the function of intestinal stem and progenitor cells, but also their capacity to initiate tumours.

Bardoxolone Methyl Prevents High-Fat Diet-Induced Colon Inflammation in Mice

Obesity induces chronic, low-grade inflammation, which increases the risk of colon cancer. We investigated the preventive effects of Bardoxolone methyl (BARD) on high-fat diet (HFD)-induced inflammation in a mouse colon. Male C57BL/6J mice (n=7) were fed a HFD (HFD group), HFD plus BARD (10 mg/kg) in drinking water (HFD/BARD group), or normal laboratory chow diet (LFD group) for 21 weeks. In HFD mice, BARD reduced colon thickness and decreased colon weight per length. This was associated with an increase in colon crypt depth and the number of goblet cells per crypt. BARD reduced the expression of F4/80 and CD11c but increased CD206 and IL-10, indicating an anti-inflammatory effect. BARD prevented an increase of the intracellular pro-inflammatory biomarkers (NF-қB, p NF-қB, IL-6, TNF-α) and cell proliferation markers (Cox2 and Ki67). BARD prevented fat deposition in the colon wall and prevented microbial population changes. Overall, we report the preventive effects of BARD on colon inflammation in HFD-fed mice through its regulation of macrophages, NF-қB, cytokines, Cox2 and Ki67, fat deposition and microflora.

The pathogenesis and treatment of cardiac atrophy in cancer cachexia

Cancer cachexia is a multifactorial syndrome characterized by a progressive loss of skeletal muscle mass associated with significant functional impairment. In addition to a loss of skeletal muscle mass and function, many patients with cancer cachexia also experience cardiac atrophy, remodeling, and dysfunction, which in the field of cancer cachexia is described as cardiac cachexia. The cardiac alterations may be due to underlying heart disease, the cancer itself, or problems initiated by the cancer treatment and, unfortunately, remains largely underappreciated by clinicians and basic scientists. Despite recent major advances in the treatment of cancer, little progress has been made in the treatment of cardiac cachexia in cancer, and much of this is due to lack of information regarding the mechanisms. This review focuses on the cardiac atrophy associated with cancer cachexia, describing some of the known mechanisms and discussing the current and future therapeutic strategies to treat this condition. Above all else, improved awareness of the condition and an increased focus on identification of mechanisms and therapeutic targets will facilitate the eventual development of an effective treatment for cardiac atrophy in cancer cachexia.

Metabonomic Profiling Reveals Cancer Chemopreventive Effects of American Ginseng on Colon Carcinogenesis in Apc(Min/+) Mice

American ginseng (Panax quinquefolius L.) is one of the most commonly used herbal medicines in the West. It has been reported to possess significant antitumor effects that inhibit the process of carcinogenesis. However, the mechanisms underlying its anticancer effects remain largely unresolved. In this study, we investigated the cancer chemopreventive effects of American ginseng on the progression of high fat (HF) diet-enhanced colorectal carcinogenesis with a genetically engineered Apc(Min/+) mouse model. The metabolic alterations in sera of experimental mice perturbed by HF diet intervention as well as the American ginseng treatment were measured by gas chromatography time-of-flight mass spectrometry (GC-TOFMS) and liquid chromatography time-of-flight mass spectrometry (LC-TOFMS) analysis. American ginseng treatment significantly extended the life span of the Apc(Min/+) mouse. Significant alterations of metabolites involving amino acids, organic acids, fatty acids, and carbohydrates were observed in Apc(Min/+) mouse in sera, which were attenuated by American ginseng treatment and concurrent with the histopathological improvement with significantly reduced tumor initiation, progression and gut inflammation. These metabolic changes suggest that the preventive effect of American ginseng is associated with attenuation of impaired amino acid, carbohydrates, and lipid metabolism. It also appears that American ginseng induced significant metabolic alterations independent of the Apc(Min/+) induced metabolic changes. The significantly altered metabolites induced by American ginseng intervention include arachidonic acid, linolelaidic acid, glutamate, docosahexaenoate, tryptophan, and fructose, all of which are associated with inflammation and oxidation. This suggests that American ginseng exerts the chemopreventive effects by anti-inflammatory and antioxidant mechanisms.

Regular exercise decreases liver tumors development in hepatocyte-specific PTEN-deficient mice independently of steatosis

BACKGROUND & AIMS

Unhealthy lifestyles predispose people to non-alcoholic steatohepatitis (NASH), which may further result in the development of hepatocellular carcinoma (HCC). Although NASH patients benefit from physical activity, it is unknown whether regular exercise reduces the risk of developing HCC. Therefore, we studied the effect of regular exercise on the development of HCC in male hepatocyte-specific PTEN-deficient mice (AlbCrePten(flox/flox)), which develop steatohepatitis and HCC spontaneously.

METHODS

Mice were fed a standardized 10% fat diet and were randomly divided into exercise or sedentary groups. The exercise group ran on a motorized treadmill for 60 min/day, 5 days/week during 32 weeks.

RESULTS

After 32 weeks of regular exercise, 71% of exercised mice developed nodules larger than 15 mm(3)vs. 100% of mice in the sedentary group. The mean number of tumors per liver was reduced by exercise, as well as the total tumoral volume per liver. Exercise did not affect steatosis and had no effect on the non-alcoholic fatty liver disease (NAFLD) Activity Score (NAS). Exercise decreased tumor cell proliferation. Mechanistically, exercise stimulated the phosphorylation of AMPK and its substrate raptor, which decreased the kinase activity of mTOR.

CONCLUSIONS

These data show a beneficial effect of regular exercise on the development of HCC in an experimental model of NASH and offer a rationale for encouraging predisposed patients to increase their physical activity for the prevention of HCC.

Dietary and metabolic control of stem cell function in physiology and cancer

Organismal diet has a profound impact on tissue homeostasis and health in mammals. Adult stem cells are a keystone of tissue homeostasis that alters tissue composition by balancing self-renewal and differentiation divisions. Because somatic stem cells may respond to shifts in organismal physiology to orchestrate tissue remodeling and some cancers are understood to arise from transformed stem cells, there is a likely possibility that organismal diet, stem cell function, and cancer initiation are interconnected. Here we will explore the emerging effects of diet on nutrient-sensing pathways active in mammalian tissue stem cells and their relevance to normal and cancerous growth.

Exercise effects on polyp burden and immune markers in the ApcMin/+ mouse model of intestinal tumorigenesis

Many observational epidemiologic studies suggest an association between exercise and colon cancer risk. The mechanisms contributing to a preventative effect of exercise on colon cancer are complex and multifaceted. Altered immune system function is one possible mechanism that has been largely unexplored. Therefore, the purpose of this study was to examine the effects of exercise on markers associated with macrophages and select T cell populations in a mouse model of intestinal tumorigenesis and to relate this to polyp characteristics. Male Apc^Min/+ mice were randomly assigned to either sedentary (Sed) or exercise (Ex) treatment (n=6–9/group). The exercise treatment consisted of treadmill running for 1 h/day and 6 days a week at 15 m/min from 4 until 16 weeks of age. Intestinal polyps were counted and categorized by size. Mucosal tissue was analyzed for mRNA expression of overall macrophages (F4/80), for genes associated with M1 (IL-12, IL-23 and Nos2) and M2 (CD206, IL-10, IL-4, CCL17, CCL22 and Arg-1) macrophages and the macrophage chemoattractants MCP-1, fetuin A and CXCL14. Markers for cytotoxic T cells (CTLs) and regulatory T cells were also examined by measuring mRNA expression of CD8 and Foxp3, respectively. While there was no significant difference in overall polyp number between the groups (Sed, 23.3±4.3; and Ex, 16.5±4.3), Ex did have a reduction in the number of large polyps (Sed, 6.1±1.1; and Ex, 3.0±0.6) (P<0.05). This was consistent with a decrease in spleen weight (P<0.05). Similarly, Ex reduced mRNA expression of overall macrophages (F4/80) as well as markers associated with both M1 (IL-12) and M2 (CD206, CCL22 and Arg-1) subtypes (P<0.05) but there was no significant decrease in macrophage chemoattractants. CD8 expression was increased while Foxp3 expression was decreased with Ex (P<0.05). Overall the data provide important new information on immune regulation as a possible mechanism for the documented benefits of exercise training on reducing colon cancer progression.

Reduction of intestinal polyp formation in min mice fed a high-fat diet with aloe vera gel extract

Aloe vera gel supercritical CO2 extract (AVGE) has been shown to contain five phytosterols, reduce visceral fat accumulation, and influence the metabolism of glucose and lipids in animal model experiments. Recent epidemiologic studies have shown that obesity is an established risk factor for several cancers including colorectal cancer. Therefore, we examined the effects of AVGE on intestinal polyp formation in Apc-deficient Min mice fed a high-fat diet. Male Min mice were divided into normal diet (ND), high fat diet (HFD), low dose AVGE (HFD+LAVGE) and high dose AVGE (HFD+HAVGE) groups. The ND group received AIN-93G diet and the latter 3 groups were given modified high-fat AIN-93G diet (HFD) for 7 weeks. AVGE was suspended in 0.5% carboxymethyl cellulose (CMC) and administered orally to mice in HFD+LAVGE and HFD+HAVGE groups every day (except on Sunday) for 7 weeks at a dose of 3.75 and 12.5 mg/kg body weight, respectively. ND and HFD groups received 0.5% CMC alone. Between weeks 4 and 7, body weights in the HFD and HFD+LAVGE groups were reduced more than those in the ND group. However, body weights were not reduced in the HFD+HAVGE group. Mice were sacrificed at the end of the experiment and their intestines were scored for polyps. No significant differences were observed in either the incidence and multiplicity of intestinal polyps (≥0.5 mm in a diameter) among the three groups fed HFD. However, when intestinal polyps were categorized by their size into 0.5-1.4, 1.5-2.4, or ≥2.5 mm, the incidence and multiplicity of large polyps (≥2.5 mm) in the intestine in the HFD+HAVGE group were significantly lower than those in the HFD group. We measured plasma lipid (triglycerides and total cholesterol) and adipocytokine [interleukin-6 and high molecular weight (HMW) adiponectin] levels as possible indicators of mechanisms of inhibition. The results showed that HMW adiponectin levels in the HFD group were significantly lower than those in the ND group. However, the levels in the HFD+HAVGE group were significantly higher than those in the HFD group. These results indicate that HAVGE reduced large-sized intestinal polyps and ameliorated reduction in plasma HMW adiponectin levels in Min mice fed HFD.

Exercise does not counteract the effects of a "westernized" diet on prostate cancer xenografts

BACKGROUND

The relationships between diet, exercise, and prostate cancer (PCa) remain unclear. We have previously reported that a "Western" diet promotes PCa tumor growth in vivo. Presently, we report the effects of sustained aerobic exercise on PCa progression in animals fed a high-fat diet versus a standard diet.

METHODS

Athymic mice (n = 43) were inoculated subcutaneously with human PCa (LNCaP) cells, fed ad libitum with either a high-fat or a standard diet, and randomized into forced exercising and non-exercising groups. Body weight, tumor volume, and food consumption were recorded tri-weekly. Terminal serum samples and tumor biopsies were obtained for analysis.

RESULTS

Body weight differences were not observed between the groups over time. The high-fat diet with exercise (HF-Ex) group showed significantly increased tumor growth rate compared to all other groups (P < 0.0007). Tumor growth rate of the standard diet with exercise (Std-Ex) group was reduced significantly compared to the high-fat diet without exercise (HF-No Ex) group (P = 0.0008). Significant differences (P ≤ 0.012) were observed in energy consumption (kcal) between the groups over time. Exercising mice consumed significantly more kcal than non-exercising mice, and the HF-Ex group consumed significantly more than each of the other three groups (P < 0.0007). The expression levels of p27 and p21 were increased in exercising animals, while AR expression was elevated in the HF-Ex group versus the Std-Ex and HF-No Ex groups.

CONCLUSIONS

Sustained aerobic exercise did not counteract the tumor-promotional effect of increased consumption of a high-fat diet, suggesting that diet is more influential in PCa progression than exercise. Combining exercise with a healthy diet reduced the rate of PCa progression in this model. This study may have implications for PCa risk reduction in humans.

Targeting the therapeutic effects of exercise on redox-sensitive mechanisms in the vascular endothelium during tumor progression

The American Cancer Society estimated 1.5 million new cancer cases in the United States in 2012. Although the exact number is not known, it is estimated that brain metastases occur in 20-40% of cancer patients (39). Owing to the complexity of development and the variation in tumor etiology, therapy options have been limited for a number of cancers, whereas progressive treatments have been successful for some malignancies. Combining treatment strategies has shown potential to increase positive outcomes; however, cancer remains a formidable diagnosis with no true cure. Many researchers have focused on alternative forms of cancer prevention or treatment to slow cancer progression. Studies have shown that with moderate, regular exercise signaling pathways associated with increased antioxidant activity and cellular repair are upregulated in vascular tissue; however, the physiological mechanisms are poorly understood. The purpose of this review is to examine the current literature to better understand the impact of exercise on cancer progression and tumor metastasis and discuss potential redox-related signaling in the vasculature that may be involved.

Linking inflammation to tumorigenesis in a mouse model of high-fat-diet-enhanced colon cancer

Many observational epidemiologic studies suggest an association between high-fat-diet (HFD) and colon cancer risk. However, the lack of controlled experimental studies that examine this relationship and the mechanisms involved weaken the basis for inferring a causal relationship. Inflammation plays a role in colon cancer progression and HFDs have been reported to increase inflammation; however, the inflammatory effects of HFD in colon cancer have yet to be firmly established. We examined the effects of a novel HFD that closely mimics the standard American diet (12% and 40% of total caloric intake from saturated fat and total fat, respectively) on macrophage markers and inflammatory mediators in a mouse model of intestinal tumorigenesis and relate this to polyp characteristics as well as measures of adiposity. Male Apc(Min/+) mice (7-8/group) were fed a Control Diet (Con) or novel high-fat-diet (HFD) from 4 to 12weeks of age. Body weight and body composition were measured weekly and monthly, respectively. Intestinal tissue was analyzed for polyp burden (number and size). Gene expression of macrophage markers and inflammatory mediators were examined in the adipose tissue and polyps. The HFD increased the expression of macrophage markers and inflammatory mediators in the adipose tissue (F4/80, CD11c, TLR-4 and MCP-1) and tumor microenvironment (IL-12, MCP-1, IL-6 and TNF-α). As expected, the HFD increased body weight, body fat percent, fat mass and blood glucose (P<0.05), and was associated with an increase in the number of large polyps (P<0.05) but not total polyps. In summary, consumption of a HFD, similar in macronutrient composition to the standard American diet, altered the expression of macrophage phenotypic markers and inflammatory mediators in adipose tissue and intestinal polyps and this was associated with increased tumorigenesis.

Control of nutrient stress-induced metabolic reprogramming by PKCζ in tumorigenesis

Tumor cells have high-energetic and anabolic needs and are known to adapt their metabolism to be able to survive and keep proliferating under conditions of nutrient stress. We show that PKCζ deficiency promotes the plasticity necessary for cancer cells to reprogram their metabolism to utilize glutamine through the serine biosynthetic pathway in the absence of glucose. PKCζ represses the expression of two key enzymes of the pathway, PHGDH and PSAT1, and phosphorylates PHGDH at key residues to inhibit its enzymatic activity. Interestingly, the loss of PKCζ in mice results in enhanced intestinal tumorigenesis and increased levels of these two metabolic enzymes, whereas patients with low levels of PKCζ have a poor prognosis. Furthermore, PKCζ and caspase-3 activities are correlated with PHGDH levels in human intestinal tumors. Taken together, this demonstrates that PKCζ is a critical metabolic tumor suppressor in mouse and human cancer.

Effects of swim training on liver carcinogenesis in male Wistar rats fed a low-fat or high-fat diet

The present study aimed to investigate the beneficial effects of swim training on the promotion–progression stages of rat liver carcinogenesis. Male Wistar rats were submitted to chemically induced liver carcinogenesis and allocated into 4 major groups, according their dietary regimen (16 weeks) and swim training of 5 days per week (8 weeks): 2 groups were fed low-fat diet (LFD, 6% fat) and trained or not trained and 2 groups were fed high-fat diet (HFD, 21% fat) and trained or not trained. At week 20, the animals were killed and liver samples were processed for histological analyses; immunohistochemical detection of persistent or remodeling preneoplastic lesions (pPNL and rPNL) expressing placental glutathione S-transferase (GST-P) enzyme; or proliferating cell nuclear antigen (PCNA), cleaved caspase-3, and bcl-2 protein levels by Western blotting or malonaldehyde (MDA) and total glutathione detection by HPLC. Overall analysis indicated that swim training reduced the body weight and body fat in both LFD and HFD groups, normalized total cholesterol levels in the HFD group while decreased the MDA levels, increased glutathione levels and both number of GST-P-positive pPNL and hepatocellular adenomas in LFD group. Also, a favorable balance in PCNA, cleaved caspase-3, and bcl-2 levels was detected in the liver from the LFD-trained group in relation to LFD-untrained group. The findings of this study indicate that the swim training protocol as a result of exercise postconditioning may attenuate liver carcinogenesis under an adequate dietary regimen with lowered fat intake.

Linking tumor-associated macrophages, inflammation, and intestinal tumorigenesis: role of MCP-1

Tumor-associated macrophages are associated with poor prognosis in certain cancers. Monocyte chemoattractant protein 1 (MCP-1) is thought to be the most important chemokine for recruitment of macrophages to the tumor microenvironment. However, its role on tumorigenesis in a genetic mouse model of colon cancer has not been explored. We examined the role of MCP-1 on tumor-associated macrophages, inflammation, and intestinal tumorigenesis. Male Apc(Min/+), Apc(Min/+)/MCP-1(-/-) or wild-type mice were euthanized at 18 wk of age and intestines were analyzed for polyp burden, apoptosis, proliferation, β-catenin, macrophage number and phenotype, markers for cytotoxic T lymphocytes and regulatory T cells, and inflammatory mediators. MCP-1 deficiency decreased overall polyp number by 20% and specifically large polyp number by 45% (P < 0.05). This was consistent with an increase in apoptotic cells (P < 0.05), but there was no change detected in proliferation or β-catenin. MCP-1 deficiency decreased F4/80-positive cells in both the polyp tissue and surrounding intestinal tissue (P < 0.05) as well as expression of markers associated with M1 (IL-12 and IL-23) and M2 macrophages (IL-13, CD206, TGF-β, and CCL17) (P < 0.05). MCP-1 knockout was also associated with increased cytotoxic T lymphocytes and decreased regulatory T cells (P < 0.05). In addition, MCP-1(-/-) offset the increased mRNA expression of IL-1β and IL-6 in intestinal tissue and IL-1β and TNF-α in polyp tissue (P < 0.05), and prevented the decrease in SOCS1 expression (P < 0.05). We demonstrate that MCP-1 is an important mediator of tumor growth and immune regulation that may serve as an important biomarker and/or therapeutic target in colon cancer.

Bile acids: from digestion to cancers

Bile acids (BAs) are cholesterol metabolites that have been extensively studied these last decades. BAs have been classified in two groups. Primary BAs are synthesized in liver, when secondary BAs are produced by intestinal bacteria. Recently, next to their ancestral roles in digestion and fat solubilization, BAs have been described as signaling molecules involved in many physiological functions, such as glucose and energy metabolisms. These signaling pathways involve the activation of the nuclear receptor FXRα or of the G-protein-coupled receptor TGR5. These two receptors have selective affinity to different types of BAs and show different expression patterns, leading to different described roles of BAs. It has been suggested for long that BAs could be molecules linked to tumor processes. Indeed, as many other molecules, regarding analyzed tissues, BAs could have either protective or pro-carcinogen activities. However, the molecular mechanisms responsible for these effects have not been characterized yet. It involves either chemical properties or their capacities to activate their specific receptors FXRα or TGR5. This review highlights and discusses the potential links between BAs and cancer diseases and the perspectives of using BAs as potential therapeutic targets in several pathologies.

Marie Ménard apples with high polyphenol content and a low-fat diet reduce 1,2-dimethylhydrazine-induced colon carcinogenesis in rats: effects on inflammation and apoptosis

Inflammation may increase cancer risk, therefore, we studied whether polyphenol-rich Marie Ménard (MM) apples with reported anti-inflammatory activity prevent 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats and, likewise whether high-fat (HF) diet promoting carcinogenesis, may affect inflammation. DMH-induced rats were fed for 15 weeks with: an HF diet (23% corn oil w/w); an HF diet containing 7.6% w/w lyophilized MM (apple diet (AD)); a low-fat (LF) diet and an HF diet containing piroxicam (PXC) (0.01% w/w) as control. Mucin depleted foci (MDF), precancerous lesions in the colon, were dramatically reduced in the AD, LF, and PXC groups compared with the HF. Peritoneal macrophage activation, an index of systemic inflammation, was significantly decreased in the AD, LF, and PXC groups. TNF-α, iNOS, IL-1β, IL-6 m-RNA expression in the colon, as well as CD68 cells and plasmatic PGE2 were lower in the AD, but not in the LF group. Apoptosis in the MDF of both the AD and LF-fed rats was significantly higher than in HF rats. In conclusion, AD has a strong chemopreventive effect, reducing inflammation, and increasing apoptosis, while the chemopreventive effect of the LF diet seems mediated mainly by increased apoptosis in MDF.

The effect of exercise on IL-6-induced cachexia in the Apc ( Min/+) mouse

BACKGROUND

Cachexia involves unintentional body weight loss including diminished muscle and adipose tissue mass and is associated with an underlying disease. Systemic overexpression of IL-6 accelerates cachexia in the Apc(Min/+) mouse, but does not induce wasting in control C57BL/6 mice. With many chronic diseases, chronic inflammation and metabolic dysfunction can be improved with moderate exercise. A direct effect of regular moderate exercise on the prevention of IL-6-induced cachexia in the Apc(Min/+) mouse has not been investigated. The purpose of this study was to assess the effects of exercise on the development of cachexia in the Apc(Min/+) mouse.

METHODS

Mice were randomly assigned to moderate treadmill exercise (18 m/min, 1 h, 6 days/week, 5% grade) or cage control (CC) groups from 6 to 14 weeks of age. At 12 weeks of age, mice were electroporated with either IL-6-containing or control plasmid into the quadriceps muscle. Mice were killed after 2 weeks of systemic IL-6 overexpression or control treatment.

RESULTS

IL-6 overexpression induced an 8% loss in body weight in CC mice, which was significantly attenuated by exercise. IL-6 overexpression in CC mice increased fasting insulin and triglyceride levels, which were normalized by exercise, and associated with increased oxidative capacity, an induction of AKT signaling, and a repression of AMPK signaling in muscle. These exercise-induced changes occurred despite elevated inflammatory signaling in skeletal muscle.

CONCLUSION

We conclude that moderate-intensity exercise can attenuate IL-6-dependent cachexia in Apc(Min/+) mice, independent of changes in IL-6 concentration and muscle inflammatory signaling. The exercise effect was associated with improved insulin sensitivity and improved energy status in the muscle.

The impact of commercial rodent diets on the induction of tumours and flat aberrant crypt foci in the intestine of multiple intestinal neoplasia mice

A large variation in spontaneous tumour development in the multiple intestinal neoplasia (Min) mouse model between laboratories has been reported. The composition of the diet might be an important factor. We examined the impact of five commercial rodent diets: the natural ingredient breeding diet Harlan Teklad 2018 (HT), the purified breeding diet AIN93G, the natural ingredient maintenance diet RM1, and the purified maintenance diets AIN93M and AIN76A, on the spontaneous intestinal tumorigenesis in the Min mouse model. The Min mice were fed one of two breeding diets during gestation and until four weeks of age, thereafter one of the three maintenance diets. Min mice bred on the breeding diet HT had significantly higher numbers and incidences of tumours in the colon, but fewer tumours in the small intestine than the breeding diet AIN93G. The maintenance diet RM1 gave a significantly higher number of small intestinal and colonic tumours and precancerous lesions called flat aberrant crypt foci (ACF) compared with the maintenance diets AIN93M and AIN76A. These findings show the importance of defining the type of diet used in experimental intestinal carcinogenesis studies, and that the diet should be taken into consideration when comparing results from different studies with Min mice.

Intestinal inflammatory cytokine response in relation to tumorigenesis in the Apc(Min/+) mouse

The etiology of colon cancer is a complex phenomenon that involves both genetic and environmental factors. However, only about 20% have a familial basis with the largest fraction being attributed to environmental causes that can lead to chronic inflammation. While the link between inflammation and colon cancer is well established, the temporal sequence of the inflammatory response in relation to tumorigenesis has not been characterized. We examined the timing and magnitude of the intestinal inflammatory cytokine response in relation to tumorigenesis in the Apc(Min/+) mouse. Apc(Min/+) mice and wildtype mice were sacrificed at one of 4 time-points: 8, 12, 16, and 20 weeks of age. Intestinal tissue was analyzed for polyp burden (sections 1, 4 and 5) and mRNA expression and protein concentration of MCP-1, IL-1β, IL-6 and TNF-α (sections 2 and 3). The results show that polyp burden was increased at 12, 16 and 20 weeks compared to 8 weeks (P<0.05). Gene expression (mRNA) of MCP-1, IL-1β, IL-6 and TNF-α was increased in sections 2 and 3 starting at week 12 (P<0.05), with further increases in MCP-1, IL-1β and IL-6 at 16 weeks (P<0.05). Protein concentration for these cytokines followed a similar pattern in section 3. Similarly, circulating MCP-1 was increased at 12 weeks (P<0.05) and then again at 20 weeks (P<0.05). In general, overall polyp number and abundance of large polyps were significantly correlated with the inflammatory cytokine response providing further support for a relationship between polyp progression and these markers. These data confirm the association between intestinal cytokines and tumorigenesis in the Apc(Min/+) mouse and provide new information on the timing and magnitude of this response in relation to polyp development. These findings may lead to the development of inflammatory mediators as important biomarkers for colon cancer progression. Further, these data may be relevant in the design of future investigations of therapeutic interventions to effectively target inflammatory processes in rodent models.

Effects of physical activity on cancer prevention

Results of most epidemiological and laboratory studies suggest an inverse relationship between regular exercise and the risk of certain malignancies, such as intestinal, colon, pancreatic, breast, lung, skin, mammary, endometrial, and prostate cancer. However, physical activity can have different influence on carcinogenesis, depending on energy supply and the age of the subject as well as strength, frequency, and length of exercise. The biochemical and molecular basis of the interaction between aerobic physical activity and tumorigenic processes remains poorly understood. Physical activity may generate reactive oxygen species (ROS) to a different extent. Mild oxidative stress caused by moderate physical activity can activate cellular stress response signaling and potentiate cellular antioxidant defense capacity. However, accumulation of relatively large amounts of ROS as a consequence of exhaustive exercise can either directly damage DNA, causing mutation, or promote tumorigenesis by activating proinflammatory signaling. This review highlights the effects of physical activity on various malignancies in the context of redox status modulated during exercise.

The regulation of skeletal muscle protein turnover during the progression of cancer cachexia in the Apc(Min/+) mouse

Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The Apc(Min/+) mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the Apc(Min/+) mouse is not known. Cachexia progression was studied in Apc(Min/+) mice that were either weight stable (WS) or had initial (≤5%), intermediate (6-19%), or extreme (≥20%) body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight loss. Muscle IGF-1 mRNA expression and mTOR targets were suppressed with the progression of body weight loss, while muscle AMPK phosphorylation (Thr 172), AMPK activity, and raptor phosphorylation (Ser 792) were not increased with the initiation of weight loss, but were induced as cachexia progressed. ATP dependent protein degradation increased during the initiation and progression of cachexia. However, ATP independent protein degradation was not increased until cachexia had progressed beyond the initial phase. IL-6 receptor antibody administration prevented body weight loss and suppressed muscle protein degradation, without any effect on muscle %MPS or IGF-1 associated signaling. In summary, the %MPS reduction during the initiation of cachexia is associated with IGF-1/mTOR signaling repression, while muscle AMPK activation and activation of ATP independent protein degradation occur later in the progression of cachexia. IL-6 receptor antibody treatment blocked cachexia progression through the suppression of muscle protein degradation, while not rescuing the suppression of muscle protein synthesis. Attenuation of IL-6 signaling was effective in blocking the progression of cachexia, but not sufficient to reverse the process.

Effect of cyclooxygenase genotype and dietary fish oil on colonic eicosanoids in mice

Dietary ω3 fatty acids can modulate substrate availability for cyclooxygenases (COXs) and lipoxygenases, thus modulating downstream eicosanoid formation. This could be an alternative approach to using nonsteroidal anti-inflammatory drugs and other COX inhibitors for limiting Prostaglandin E(2) (PGE(2)) synthesis in colon cancer prevention. The aims of this study were to evaluate to what extent COX- and lipoxygenase-derived products could be modulated by dietary fish oil in normal colonic mucosa and to evaluate the role of COX-1 and COX-2 in the formation of these products. Mice (wild-type, COX-1 null or COX-2 null) were fed a diet supplying a broad mixture of fatty acids present in European/American diets, supplemented with either olive oil (oleate control diet) or menhaden (fish) oil ad libitum for 9-11 weeks. Colonic eicosanoid levels were measured by liquid chromatography tandem mass spectroscopy (LC-MS/MS), and proliferation was assessed by Ki67 immunohistochemistry. For the dietary alteration of colonic arachidonic acid: eicosapentaenoic ratios resulted in large shifts in formation of COX and lipoxygenase metabolites. COX-1 knockout virtually abolished PGE(2) formation, but interestingly, 12-hydroxyeicosatetraenoic (12-HETE) acid and 15-HETE formation was increased. The large changes in eicosanoid profiles were accompanied by relatively small changes in colonic crypt proliferation, but such changes in eicosanoid formation might have greater biological impact upon carcinogen challenge. These results indicate that in normal colon, inhibition of COX-2 would have little effect on reducing PGE(2) levels.

Curcumin suppresses intestinal polyps in APC Min mice fed a high fat diet

Colorectal cancer (CRC) is a leading cause of cancer deaths in the United States. Various risk factors have been associated with CRC including increasing age and diet. Epidemiological and experimental studies have implicated a diet high in fat as an important risk factor for colon cancer. High fat diets can promote obesity resulting in insulin resistance and inflammation and the development of oxidative stress, increased cell proliferation, and suppression of apoptosis. Because of the high consumption of dietary fats, especially saturated fats, by Western countries, it is of interest to see if non-nutrient food factors might be effective in preventing or delaying CRC in the presence of high saturated fat intake. Curcumin (Curcuma longa), the main yellow pigment in turmeric, was selected to test because of its reported anti-tumor activity. APC Min mice, which develop intestinal polyps and have many molecular features of CRC, were fed a diet containing 35% pork fat, 33% sucrose, and a protein and vitamin mineral mixture (HFD) with or without 0.5% curcumin. These cohorts were compared to APC Min mice receiving standard rodent chow (RC) with 8% fat. APC Min mice fed the HFD for 3 months had a 23% increase in total number of polyps compared to APC Min mice on RC. Curcumin was able to significantly reverse the accelerated polyp development associated with the HFD suggesting it may be effective clinically in helping prevent colon cancer even when ingesting high amounts of fatty foods. The anti-tumor effect of curcumin was shown to be associated with enhanced apoptosis and increased efficiency of DNA repair. Since curcumin prevented the gain in body weight seen in APC Min mice ingesting the HFD, modulation of energy metabolism may also be a factor.