Effect of a high-fat diet in development of colonic adenoma in an animal model

The burden of colorectal cancer attributable to high body mass index in China: findings from 1990 to 2021 and prediction to 2035

BACKGROUND

Colorectal cancer (CRC) incidence and mortality are rising in China, with high body mass index (BMI) established as a significant risk factor. However, comprehensive evidence regarding the BMI-attributable CRC burden in the Chinese population remains limited.

OBJECTIVE

This study aims to analyze the trend of CRC burden attributable to high BMI (BMI ≥ 25 kg/m2) in China from 1990 to 2021 and to predict its development from 2022 to 2035, in order to provide a scientific foundation for the formulation of public health policies.

METHODS

We analyzed data from the Global Burden of Disease Study 2021 (GBD 2021) to assess the BMI-attributable CRC burden in China from 1990 to 2021. Temporal trends were analyzed using Joinpoint regression models. Future projections through 2035 were generated using Bayesian age-period-cohort (BAPC) modeling. The Das Gupta method was used to explore the contribution of population growth, aging, and epidemiologic factors to these burden changes.

RESULTS

From 1990 to 2021, China's BMI-attributable CRC burden increased substantially, with ASMR and ASDR rising at annual rates of 2.393% (95% CI 2.306-2.481) and 2.305% (95% CI 2.188-2.422), respectively. The mortality and disability-adjusted life years (DALYs) rate both increased with age. Males showed higher burden rates in most age groups. Projections indicate continued increases in ASMR (2.43% annually) and ASDR (2.44% annually) through 2035. Epidemiological factors were the primary drivers, contributing 99.73% to mortality changes and 44.81% to DALYs changes.

CONCLUSIONS

The BMI-attributable CRC burden in China shows a concerning upward trajectory that is predicted to continue, with epidemiologic factors playing a major role. Urgent public health interventions targeting obesity prevention, lifestyle modification, and expanded CRC screening are needed to mitigate this growing burden.

Functional heterogeneity of endothelium-dependent vasorelaxation in different order branches of mesenteric artery in female/male mice

Although the mouse mesenteric artery is widely used as a model of resistance vessels, it is unknown which order branch is the best representative and if there is a heterogeneity of vascular activity in different orders. We systematically compared the vasorelaxation between the mouse mesenteric artery's first- and second-order branches. The first- and second-order branches of the mesenteric artery (lumen diameter of >300 μm and 179.9 ± 11.1 μm, respectively) were taken from the location close to their branching points in wide-type (WT) and TRPV4-/- (KO) mice. Vasorelaxation of the mesenteric artery was measured using a Danish DMT520A microvascular system. Acetylcholine (ACh) induced much greater vasorelaxation via TRPV4 channels/endothelium-dependent hyperpolarization (EDH/H2S) in the second-order branch. The store-operated Ca2+ entry (SOCE) mediated much greater vasorelaxation via EDH in the second-order branch than that via NO in the first-order branch. However, capsaicin-induced vasorelaxation was much greater via TRPV1/NO and TRPV1/CGRP in the first-order branch than TRPV4/EDH only in the second-order branch. Moreover, sex differences in ACh-induced vasorelaxation were obviously in the first-order branch but marginally in the second-order branch. Mechanistically, the myoendothelial gap junction (MEGJ) is involved in ACh-induced vasorelaxation in the second-order branch but not in the first-order branch. However, endothelial IKCa and SKCa functions and endothelium-independent vasorelaxation were similar for both first- and second-order branches. TRPV1/NO/CGRP mediates endothelium-dependent vasorelaxation in the first-order branch as the best representative of conduit vessels, but TRPV4/EDH/H2S mediates endothelium-dependent vasorelaxation in the second-order branch as the best representative of resistance vessels in mice.

Unraveling molecular interconnections and identifying potential therapeutic targets of significance in obesity-cancer link

Obesity, a global health concern, is associated with severe health issues like type 2 diabetes, heart disease, and respiratory complications. It also increases the risk of various cancers, including melanoma, endometrial, prostate, pancreatic, esophageal adenocarcinoma, colorectal carcinoma, renal adenocarcinoma, and pre-and post-menopausal breast cancer. Obesity-induced cellular changes, such as impaired CD8+ T cell function, dyslipidemia, hypercholesterolemia, insulin resistance, mild hyperglycemia, and fluctuating levels of leptin, resistin, adiponectin, and IL-6, contribute to cancer development by promoting inflammation and creating a tumor-promoting microenvironment rich in adipocytes. Adipocytes release leptin, a pro-inflammatory substance that stimulates cancer cell proliferation, inflammation, and invasion, altering the tumor cell metabolic pathway. Adiponectin, an insulin-sensitizing adipokine, is typically downregulated in obese individuals. It has antiproliferative, proapoptotic, and antiangiogenic properties, making it a potential cancer treatment. This narrative review offers a comprehensive examination of the molecular interconnections between obesity and cancer, drawing on an extensive, though non-systematic, survey of the recent literature. This approach allows us to integrate and synthesize findings from various studies, offering a cohesive perspective on emerging themes and potential therapeutic targets. The review explores the metabolic disturbances, cellular alterations, inflammatory responses, and shifts in the tumor microenvironment that contribute to the obesity-cancer link. Finally, it discusses potential therapeutic strategies aimed at disrupting these connections, offering valuable insights into future research directions and the development of targeted interventions.

Exploring the role of Bisphenol A in obesity-driven colorectal cancer progression: network toxicology and multi-organ pathology in animal models

Bisphenol A (BPA), an endocrine disruptor, is linked to cancer progression in estrogen-responsive tissues, but its role in promoting colorectal cancer (CRC) progression in the context of obesity remains underexplored. This study examines BPA's influence on CRC in obese Sprague-Dawley rats using network toxicology and experimental models. Computational analysis using the Database for Annotation, Visualization, and Integrated Discovery identified pathways such as "CRC" and "chemical carcinogenesis-receptor activation", implicating the PI3K-AKT pathway in IL-1 beta upregulation and BPA's role in CRC during obesity. Thirty male rats were grouped (n = 6) as follows: N (normal diet), NC (normal diet + CRC), HC (high-fat diet + CRC), NCB (normal diet + CRC + BPA), and HCB (high-fat diet + CRC + BPA). CRC was induced with 1,2-dimethylhydrazine (40 mg/kg), and BPA (25 mg/kg) was administered for 19 weeks. Although BPA exposure did not affect body weight or biochemical parameters, the HCB group exhibited significant histopathological changes in the colon, including lymphoid hyperplasia, liver damage, and increased IL-1β levels. Furthermore, diet influenced adipocyte size, exacerbating BPA's effects on CRC progression. Findings suggest BPA may worsen CRC progression in obese rats through identified pathways, promoting multi-organ pathology and underscoring the need for stricter regulations, especially for vulnerable populations. ENVIRONMENTAL IMPLICATION: Bisphenol A (BPA), a widespread environmental contaminant, is increasingly linked to serious health issues, including cancer, in susceptible populations. Our study highlights BPA's role in promoting obesity-driven colorectal cancer (CRC) progression, demonstrating its carcinogenic potential in high-risk contexts. These findings emphasize the urgent need for regulatory scrutiny of BPA exposure, particularly in obese individuals, and support the development of safer alternatives. Addressing BPA's impact can contribute to preventive health strategies and inform policies aimed at reducing environmental and public health risks associated with endocrine-disrupting chemicals.

Piperine inhibits the proliferation of colorectal adenocarcinoma by regulating ARL3-mediated endoplasmic reticulum stress

Colorectal adenocarcinoma (COAD) is a significant cause of cancer-related mortality worldwide, necessitating the identification of novel therapeutic targets and treatments. This research aimed to investigate the role of ARL3 in COAD progression and to explore the effects of Piperine on ARL3 expression, cell proliferation, epithelial-mesenchymal transition (EMT), and endoplasmic reticulum (ER) stress. Bioinformatics analysis of The Cancer Genome Atlas (TCGA)-COAD, GSE39582, and GSE44861 datasets assessed ARL3 expression levels. Immunohistochemical data from the Human Protein Atlas (HPA) database confirmed ARL3 overexpression in COAD. The association of ARL3 with COAD clinical parameters and prognosis was also examined. COAD cells were treated with Piperine, and in vitro assays evaluated cell proliferation, apoptosis, EMT marker expression, and ER stress (ERS) responses. ARL3 overexpression in COAD correlated with poor prognosis and varied across pathological stages. Piperine treatment inhibited COAD cell proliferation in a concentration- and time-dependent manner, as indicated by reduced Ki-67 levels and decreased colony-forming ability. Piperine induced S-phase cell cycle arrest and facilitated apoptosis in COAD cells, evidenced by changes in Bax, Bcl-2, cleaved caspase-3, and cleaved Poly (ADP-ribose) polymerase (PARP) levels. Moreover, Piperine downregulated ARL3 expression in COAD cells, thereby suppressing transforming growth factor beta (TGF-β)-induced EMT. Additionally, Piperine attenuated the ARL3-mediated ER stress response, significantly reducing binding immunoglobulin protein (BiP), inositol-requiring enzyme 1 alpha (p-IRE1α), activating transcription factor 6 (ATF6), and C/EBP homologous protein (CHOP) levels. Piperine exerts anti-cancer effects in COAD by modulating ARL3 expression, disrupting cell cycle progression, inhibiting the EMT pathway, and regulating ERS. These findings suggest that Piperine holds promise as a therapeutic agent for COAD through its targeting of ARL3.

Cold-pressed extraction of perilla seed oil enriched with alpha-linolenic acid mitigates tumour progression and restores gut microbial homeostasis in the AOM/DSS mice model of colitis-associated colorectal cancer

The present investigation explores into the influence of dietary nutrients, particularly alpha-linolenic acid (ALA), a plant-derived omega-3 fatty acid abundant in perilla seed oil (PSO), on the development of colitis-associated colorectal cancer (CRC). The study employs a mouse model to scrutinize the effects of ALA-rich PSO in the context of inflammation-driven CRC. Perilla seeds were subjected to oil extraction, and the nutritional composition of the obtained oil was analysed. Male ICR mice, initiated at four weeks of age, were subjected to diets comprising 5%, 10%, or 20% PSO, 10% fish oil, or 5% soybean oil. All groups, with the exception of the control group (5% soybean oil), underwent induction with azoxymethane (AOM) and dextran sulphate sodium (DSS) to instigate CRC. Disease development, colon samples, preneoplastic lesions, dysplasia, and biomarkers were meticulously evaluated. Furthermore, gut microbiota composition was elucidated through 16S rRNA sequencing. The analysis revealed that PSO contained 61.32% ALA and 783.90 mg/kg tocopherols. Mice subjected to diets comprising 5% soybean or 10% fish oil exhibited higher tumour incidence, burden, multiplicity, and aberrant crypt counts. Remarkably, these parameters were significantly reduced in mice fed a 5% PSO diet. Additionally, 5% PSO-fed mice displayed reduced proliferative and pro-inflammatory markers in colon tissues, coupled with an alleviation of AOM/DSS-induced gut dysbiosis. Notably, PSO demonstrated inhibitory effects on colitis-associated CRC in the AOM/DSS mice model, achieved through the suppression of proliferative and pro-inflammatory protein levels, and mitigation of gut dysbiosis, with discernible efficacy observed at a 5% dietary concentration.

Gut microbiome-metabolites axis: A friend or foe to colorectal cancer progression

An expanding corpus of research robustly substantiates the complex interrelation between gut microbiota and the onset, progression, and metastasis of colorectal cancer. Investigations in both animal models and human subjects have consistently underscored the role of gut bacteria in a variety of metabolic activities, driven by dietary intake. These activities include amino acid metabolism, carbohydrate fermentation, and the generation and regulation of bile acids. These metabolic derivatives, in turn, have been identified as significant contributors to the progression of colorectal cancer. This thorough review meticulously explores the dynamic interaction between gut bacteria and metabolites derived from the breakdown of amino acids, fatty acid metabolism, and bile acid synthesis. Notably, bile acids have been recognized for their potential carcinogenic properties, which may expedite tumor development. Extensive research has revealed a reciprocal influence of gut microbiota on the intricate spectrum of colorectal cancer pathologies. Furthermore, strategies to modulate gut microbiota, such as dietary modifications or probiotic supplementation, may offer promising avenues for both the prevention and adjunctive treatment of colorectal cancer. Nevertheless, additional research is imperative to corroborate these findings and enhance our comprehension of the underlying mechanisms in colorectal cancer development.

Role of Hydrogen Sulfide in Inflammatory Bowel Disease

Hydrogen sulfide (H2S), originally known as toxic gas, has now attracted attention as one of the gasotransmitters involved in many reactions in the human body. H2S has been assumed to play a role in the pathogenesis of many chronic diseases, of which the exact pathogenesis remains unknown. One of them is inflammatory bowel disease (IBD), a chronic intestinal disease subclassified as Crohn's disease (CD) and ulcerative colitis (UC). Any change in the amount of H2S seems to be linked to inflammation in this illness. These changes can be brought about by alterations in the microbiota, in the endogenous metabolism of H2S and in the diet. As both too little and too much H2S drive inflammation, a balanced level is needed for intestinal health. The aim of this review is to summarize the available literature published until June 2023 in order to provide an overview of the current knowledge of the connection between H2S and IBD.

A lipid metabolism-related gene signature reveals dynamic immune infiltration of the colorectal adenoma-carcinoma sequence

BACKGROUND

Lipid metabolism-related genes (LMRGs) have been reported to be correlated with the immune infiltration of colorectal cancer (CRC). This study aimed to investigate the immune infiltration characteristics along the colorectal adenoma-carcinoma sequence (ACS) based on LMRGs.

METHODS

Gene expression data of colorectal adenoma and carcinoma samples were obtained from the public databases. The "limma" package was applied to determine the differentially expressed LMRGs. Unsupervised consensus clustering was used to cluster colorectal samples. The features of the tumor microenvironment were analyzed by the "ESTIMATE", "GSVA", and "TIDE" algorithms.

RESULTS

The expression of 149 differentially expressed LMRGs was defined as the LMRG signature. Based on this signature, the adenoma and carcinoma samples were divided into three clusters. Unexpectedly, these sequential clusters showed a directional relationship and collectively constituted the progressive course of colorectal ACS. Interestingly, the LMRG signature revealed that adenoma progression was accompanied by a progressive loss of immune infiltration and a stepwise establishment of a cold microenvironment, but carcinoma progression was characterized by a progressive gain of immune infiltration and a gradual establishment of a hot microenvironment.

CONCLUSIONS

The LMRG signature reveals dynamic immune infiltration along the colorectal ACS, which substantially changes the understanding of the tumor microenvironment of CRC carcinogenesis and provides novel insight into the role of lipid metabolism in this process.

Maternal high-fat diet increases the susceptibility of offspring to colorectal cancer via the activation of intestinal inflammation

A high-fat diet plays a key role in the pathogenesis of colorectal cancer, and this effect on the gut can also occur in the offspring of mothers with a high-fat diet. In this review, we discuss the role of a high-fat diet in the pathogenesis of colorectal cancer and summarize the effects of a maternal high-fat diet on the activation of inflammation and development of colorectal cancer in offspring. Studies have found that a maternal high-fat diet primarily induces an inflammatory response in the colorectal tissue of both the mother herself and the offspring during pregnancy. This leads to the accumulation of inflammatory cells in the colorectal tissue and the release of inflammatory cytokines, which further activate the NF-κb and related inflammatory signaling pathways. Research suggests that high levels of lipids and inflammatory factors from mothers with a high-fat diet are passed to the offspring through the transplacental route, which induces colorectal inflammation, impairs the intestinal microecological structure and the intestinal barrier, and interferes with intestinal development in the offspring. This in turn activates the NF-κb and related signaling pathways, which further aggravates intestinal inflammation. This process of continuous inflammatory stimulation and repair may promote the uncontrolled proliferation of colorectal mucosal cells in the offspring, thus increasing their susceptibility to colorectal cancer.

The Potential Chemopreventive Effect of Andrographis paniculata on 1,2-Dimethylhydrazine and High-Fat-Diet-Induced Colorectal Cancer in Sprague Dawley Rats

Colorectal cancer (CRC) is responsible for a notable rise in the overall mortality rate. Obesity is found to be one of the main factors behind CRC development. Andrographis paniculata is a herbaceous plant famous for its medicinal properties, particularly in Southeast Asia for its anti-cancer properties. This study examines the chemopreventive impact of A. paniculata ethanolic extract (APEE) against a high-fat diet and 1,2-dimethylhydrazine-induced colon cancer in Sprague Dawley rats. Sprague Dawley rats were administered 1,2-dimethylhydrazine (40 mg/kg, i.p. once a week for 10 weeks) and a high-fat diet (HFD) for 20 weeks to induce colorectal cancer. APEE was administered at 125 mg/kg, 250 mg/kg, and 500 mg/kg for 20 weeks. At the end of the experiment, blood serum and organs were collected. DMH/HFD-induced rats had abnormal crypts and more aberrant crypt foci (ACF). APEE at a dose of 500 mg/kg improved the dysplastic state of the colon tissue and caused a 32% reduction in the total ACF. HFD increased adipocyte cell size, while 500 mg/kg APEE reduced it. HFD and DMH/HFD rats had elevated serum insulin and leptin levels. Moreover, UHPLC-QTOF-MS analysis revealed that APEE was rich in anti-cancer phytochemicals. This finding suggests that APEE has anti-cancer potential against HFD/DMH-induced CRC and anti-adipogenic and anti-obesity properties.

Ficus dubia latex extract prevent DMH-induced rat early colorectal carcinogenesis through the regulation of xenobiotic metabolism, inflammation, cell proliferation and apoptosis

Ficus dubia latex is recognized as a remedy in Asian traditional medicine with various therapeutic effects. The present study aimed to determine the preventive action of Ficus dubia latex extract (FDLE) on 1,2-dimethylhydrazine (DMH)-induced rat colorectal carcinogenesis and its mechanisms. The experiment included an initiation model in which rats were orally administered with FDLE daily for 1 week before DMH injection until the end of the experiment, while only after DMH injection until the end in the post-initiation model. The results firstly indicated that FDLE treatment could reduce the level of methylazoxymethanol (MAM) in rat colonic lumen by inhibition of the activities of both phase I xenobiotic metabolizing enzymes in the liver and β-glucuronidase in the colon, leading to reduced DNA methylation in colonic mucosal cells, related to the number of ACF in the initiation stage. Besides, FDLE modulated the inflammation which could suppress the growth and induce apoptosis of aberrant colonic mucosal cells, leading to retardation of ACF multiplicity. Therefore, FDLE showed the ability to suppress the DMH-induced rat ACF formation and inflammation promoted growth of ACF. In conclusion, FDLE had the potential to prevent carcinogens-induced rat colorectal carcinogenesis in the initiation stage.

Secondary Bile Acids and Tumorigenesis in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common and deadly cancers in the world and is a typical inflammatory tumor. In recent years, the incidence of CRC has been increasing year by year. There is evidence that the intake of high-fat diet and overweight are associated with the incidence of CRC, among which bile acids play a key role in the pathogenesis of the disease. Studies on the relationship between bile acid metabolism and the occurrence of CRC have gradually become a hot topic, improving the understanding of metabolic factors in the etiology of colorectal cancer. Meanwhile, intestinal flora also plays an important role in the occurrence and development of CRC In this review, the classification of bile acids and their role in promoting the occurrence of CRC are discussed, and we highlights how a high-fat diet affects bile acid metabolism and destroys the integrity of the intestinal barrier and the effects of gut bacteria.

A two-front nutritional environment fuels colorectal cancer: perspectives for dietary intervention

Colorectal cancer (CRC) develops and progresses in a nutritional environment comprising a continuously changing luminal cocktail of external dietary and microbial factors on the apical side, and a dynamic host-related pool of systemic factors on the serosal side. In this review, we highlight how this two-front environment influences the bioenergetic status of colonocytes throughout CRC development from (cancer) stem cells to cancer cells in nutrient-rich and nutrient-poor conditions, and eventually to metastatic cells, which, upon entry to the circulation and during metastatic seeding, are forced to metabolically adapt. Furthermore, given the influence of diet on the two-front nutritional environment, we discuss dietary strategies that target the specific metabolic preferences of these cells, with a possible impact on colon cancer cell bioenergetics and CRC outcome.

Protective effects of rosmarinic acid against azoxymethane-induced colorectal cancer in rats

Colorectal cancer (CRC) incidence is increasing gradually and has been become one of the most common cancers worldwide. Hence, it is important to discover cheap, naturally occurring compounds to be effective in suppressing the devastating effect of colon-related tumors. Rosmarinic acid (RA), one of the compounds of plant origin, possesses attractive features for use as an agent for cancer prevention and treatment. This study investigated the ability of RA to prevent azoxymethane (AOM)-induced rat colon carcinogenesis by evaluating the effect of RA on tumor formation and circulatory oxidant-antioxidant status. Moreover, plasma levels of adiponectin (APN) monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) were detected by enzyme linked immunosorbent assay. The animals were divided into three groups: Control, AOM, and AOM + RA. Rats were fed a modified pellet diet (15.8% peanut oil was added to the standard diet) during the experimental period. Colon cancer was formed by applying 15 mg/kg AOM intraperitoneal once a week for 4 weeks in both the CRC group and AOM + RA group. Besides AOM, AOM + RA group received 5 mg/kg body weight RA orally every day during the study. The results showed that adenocarcinoma rates formed 87.5% of the AOM group. With treatment of RA, a reduction in the incidence of adenocarcinoma was observed in the AOM + RA group. The plasma MCP-1, IL-6, and TO levels were significantly higher, APN and TAS levels were significantly lower in the AOM group with respect to controls. In addition, there was a significant increase in TAS levels in the RA treatment group compared to the AOM group. These findings suggested that RA may be beneficial in preventing AOM-induced colon carcinogenesis formation.

Dietary Fat Intake and KRAS Mutations in Colorectal Cancer in a Moroccan Population

Epidemiologic data support an association between diet and mutations in the Kirsten-ras (KRAS) gene involved in colorectal cancer (CRC) development. This study aimed to explore the associations between fat intake and KRAS mutations in codons 12 and 13 in cases of CRC in the Moroccan population. A multicenter case-series study nested in a large-scale Moroccan CRC case-control study was conducted. Among all CRC cases recruited, 151 specimens were available for the DNA mutation analysis. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (Cis) for KRAS mutation status according to the fat intake variables. A KRAS mutation was detected in the CRC tumor of 34.4% of the patients among whom 65.4% had a single mutation at codon 12 and 34.6% had a single mutation at codon 13. Compared to low levels of consumption, a positive association was observed between high polyunsaturated fatty acids (PUFA) consumption (>16.9 g/day) and prevalence of KRAS mutations (OR = 2.15, 95% CI = 1.01-4.59). No statistically significant associations were observed for total fat, monounsaturated fatty acids, saturated fatty acids and KRAS mutations. The results of this study suggest that PUFA may be relevant in the etiology of CRC, possibly through the generation of G > A transitions at the KRAS oncogene. Further studies are needed to verify and explain this finding.

The HIV reverse transcriptase Inhibitor Tenofovir suppressed DMH/HFD-induced colorectal cancer in Wistar rats

Colon rectal cancer (CRC) is the second commonest malignancy in developed countries and a significant cause of mortality. Tenofovir reportedly reduces the risk of hepatocellular carcinoma and interferes with cell cycle and cell proliferation. The current study investigated the potential antitumor effect of tenofovir against experimentally induced CRC. CRC was induced by 1,2-dimethylhydrazine (DMH, 20 mg/kg, once a week) and high-fat diet (HFD) in Wistar rats. Rats received tenofovir at a dose of 25 or 50 mg/kg (i.p.) for 24 weeks. Tenofovir-25 failed to significantly decrease the total number of dysplasia, adenoma and adenocarcinoma and to improve histopathological changes; however, tenofovir-50 resulted in no tumors seen in the colon lumen and a significant decrease in the total number of dysplasia and no adenoma or adenocarcinoma observed compared to DMH/HFD group. Tenofovir-25 failed to attenuate DMH/HFD-induced cell proliferation, whereas tenofovir-50 significantly decreased cell proliferation revealed by the decreased PCNA expression. Tenofovir-25 also failed to attenuate DMH/HFD-induced oxidative stress, whereas tenofovir-50 significantly attenuated oxidative stress as indicated by the decreased MDA concentration and SOD activity along with the increased GSH concentrations. Moreover, tenofovir-50 decreased Bcl-2 and cyclin D1 expressions in colon tissues compared with DMH/HFD group. Tenofovir-50 also significantly decreased INF-ɤ concentration in colon tissues. These findings suggest that the high dose of tenofovir (50 mg/kg) has antitumor potential against DMH/HFD-induced CRC, which might be mediated through the inhibition of cell proliferation, oxidative stress, and inflammation.

Transcriptomic and Proteomic Study on the High-Fat Diet Combined With AOM/DSS-Induced Adenomatous Polyps in Mice

Objective

To screen and identify molecular targets and bacteria genus leading to adenomatous polyps in mouse induced by high-fat diet (HFD) +AOM/DSS using omics technology.

Methods

The molecular targets of colorectal adenoma disease were obtained from the GeneCards and OMIM database. The SPF C57BL mice were randomly divided into blank (Control) and AOM/DSS+HFD colorectal adenoma model (ADH) groups. The ADH model group was intraperitoneally injected with AOM reagent. Then, mice were given with 2.5% DSS (in free drinking water) and high-fat diet to establish the mouse model. During this period, the changes of physical signs of mice in each group were observed. After the end of modeling, HE staining was used to evaluate the histopathological change of mice. The differentially expressed genes and proteins in the Control group and ADH group were detected by RNA-seq transcriptome sequencing and Tandem Mass Tags (TMT) quantitative proteomics. The histological results were analyzed by intersection with the intestinal adenoma molecular targets obtained from the database. Moreover, the changes of intestinal flora in the two groups were examined. The correlation between targets and differential bacteria was analyzed and verified by Parallel Reaction Monitoring (PRM) to comprehensively evaluate the mouse model of adenomatous polyp induced by AOM/DSS+HFD.

Results

The general condition and histopathological results of mice confirmed that the ADH mouse model was successfully established and tubular adenoma was formed. A total of 604 genes and 42 proteins related to intestinal adenoma were obtained by histological analysis and database intersection analysis. The intestinal microflora of ADH mice was different from that of normal mice, and the constituents and abundance of intestinal flora were similar to those of human intestinal adenoma. GATA4 and LHPP were selected as potential pathological markers of the model mice by correlation analysis of targets and intestinal flora. The results of PRM verification were highly consistent with the results of RNA-Seq transcriptome sequencing and TMT analysis.

Conclusion

The pathological results, molecular pathological markers and the changes of intestinal flora suggest that the mouse ADH model is ideal for studying the transformation of inflammatory cancer. The ADH model will be helpful for understanding the occurrence and development of human colorectal cancer at the transcriptomic and proteomic level.

High fat diet, gut microbiome and gastrointestinal cancer

Gastrointestinal cancer is currently one of the main causes of cancer death, with a large number of cases and a wide range of lesioned sites. A high fat diet, as a public health problem, has been shown to be correlated with various digestive system diseases and tumors, and can accelerate the occurrence of cancer due to inflammation and altered metabolism. The gut microbiome has been the focus of research in recent years, and associated with cell damage or tumor immune microenvironment changes via direct or extra-intestinal effects; this may facilitate the occurrence and development of gastrointestinal tumors. Based on research showing that both a high fat diet and gut microbes can promote the occurrence of gastrointestinal tumors, and that a high fat diet imbalances intestinal microbes, we propose that a high fat diet drives gastrointestinal tumors by changing the composition of intestinal microbes.

The Role of Dyslipidemia in Colitis-Associated Colorectal Cancer

Dyslipidemia, characterized by metabolic abnormalities, has become an important participant in colorectal cancer (CRC). Dyslipidemia aggravates intestinal inflammation, destroys the protective mucous layer, and disrupts the balance between injury and recovery. On the other hand, antioxidants induced by oxidative stress enhance glycolysis to maintain the acquisition of ATP allowing epithelial cells with damaged genomes to survive. In the repetitive phase of colitis, survival factors enable these epithelial cells to continuously proliferate. The main purpose is to restore and rebuild damaged mucosa, mainly aiming to recover mucosal damage and reconstruct mucosa, but it is also implicated in the occurrence and malignancy of CRC. The metabolic reprogramming of aerobic glycolysis and lipid synthesis enables these transformed epithelial cells to convert raw carbohydrate and amino acid substrates, thereby synthesizing protein and phospholipid biomass. Stearoyl-CoA desaturase, responsible for the fatty acid desaturation, improves the fluidity and permeability of cell membranes, which is one of the key factors affecting metabolic rate. In response to available fat, tumor cells reprogram their metabolism to better plunder energy-rich lipids and rapidly scavenge these lipids through continuous proliferation. However, lipid metabolic disorders inhibit the function of immune-infiltrating cells in the tumor microenvironment through the cross-talk between tumor cells and immunosuppressive stromal cells, thereby providing opportunities for tumor progress. Nonsteroidal anti-inflammatory drugs and lipid-lowering drugs can decrease the formation of aberrant crypt foci, lower the burden of the adenomatous polyp, and reduce the incidence of CRC. This review provides a comprehensive understanding of dyslipidemia on tumorigenesis and tumor progression and a development prospect of lipid disorders on tumor immunity.

Biochemical and molecular aspects of 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis: a review

1,2-dimethylhydrazine (DMH) is a member in the class of hydrazines, strong DNA alkylating agent, naturally present in cycads. DMH is widely used as a carcinogen to induce colon cancer in animal models. Exploration of DMH-induced colon carcinogenesis in rodent models provides the knowledge to perceive the biochemical, molecular, and histological mechanisms of different stages of colon carcinogenesis. The procarcinogen DMH, after a series of metabolic reactions, finally reaches the colon, there produces the ultimate carcinogen and reactive oxygen species (ROS), which further alkylate the DNA and initiate the development of colon carcinogenesis. The preneolpastic lesions and histopathological observations of DMH-induced colon tumors may provide typical understanding about the disease in rodents and humans. In addition, this review discusses about the action of biotransformation and antioxidant enzymes involved in DMH intoxication. This understanding is essential to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH-induced animal colon carcinogenesis.

In Vitro and In Vivo Nutraceutical Characterization of Two Chickpea Accessions: Differential Effects on Hepatic Lipid Over-Accumulation

Dietary habits are crucially important to prevent the development of lifestyle-associated diseases. Diets supplemented with chickpeas have numerous benefits and are known to improve body fat composition. The present study was undertaken to characterize two genetically and phenotypically distinct accessions, MG_13 and PI358934, selected from a global chickpea collection. Rat hepatoma FaO cells treated with a mixture of free fatty acids (FFAs) (O/P) were used as an in vitro model of hepatic steatosis. In parallel, a high-fat diet (HFD) animal model was also established. In vitro and in vivo studies revealed that both chickpea accessions showed a significant antioxidant ability. However, only MG_13 reduced the lipid over-accumulation in steatotic FaO cells and in the liver of HFD fed mice. Moreover, mice fed with HFD + MG_13 displayed a lower level of glycemia and aspartate aminotransferase (AST) than HFD mice. Interestingly, exposure to MG_13 prevented the phosphorylation of the inflammatory nuclear factor kappa beta (NF-kB) which is upregulated during HFD and known to be linked to obesity. To conclude, the comparison of the two distinct chickpea accessions revealed a beneficial effect only for the MG_13. These findings highlight the importance of studies addressing the functional characterization of chickpea biodiversity and nutraceutical properties.

Effects of high-fat diet-induced adipokines and cytokines on colorectal cancer development

Colorectal cancer (CRC) is the third most common tumor worldwide, and recent epidemiological studies have indicated that obesity contributes to the morbidity and mortality of CRC. Furthermore, obesity‐related adipokines have been shown to be closely related to the incidence of CRC, but the underlying mechanisms are unclear. Here, we investigated the effects of high‐fat diet‐induced adipokines and cytokines on the development of CRC in vitro and in vivo. For the in vivo assays, we divided 2‐week‐old C57BL/6J‐ApcMin/J male mice into three groups: normal‐fat diet (ND), high‐fat and high‐sugar feed (HFHS), and high‐fat and low‐sugar feed (HFLS). After 1 week, all mice were injected with 20 mg·kg⁻¹ 1,2‐dimethylhydrazine once weekly for 10 consecutive weeks. Body weight, liver weight, epididymal fat weight and blood glucose levels were greatly increased in HFHS and HFLS groups compared with the ND group, and the expression levels of some adipokines and cytokines were obviously higher in HFHS or HFLS mice compared with ND mice. For the in vitro assays, HCT116 CRC cells were treated with sera of ND, HFHS or HFLS groups, or serum‐free media as a negative control. We observed that sera derived from HFHS or HFLS mice that contain excess adipokines and cytokines promoted the proliferation, migration and invasion of HCT116 cells compared with the ND sera‐conditioned medium or serum‐free medium group. Therefore, high‐fat diet‐induced adipokines and cytokines may promote the progression of CRC in vivo and in vitro.

We investigated the effects of high‐fat diet‐induced adipokines and cytokines in the development of colorectal cancer. Some adipokines and cytokines were obviously higher in obese mice than in normal mice. Obesity‐induced adipokines and cytokines promoted the proliferation, migration and invasion of HCT116 cells. Therefore, high‐fat diet‐induced adipokines and cytokines may accelerate the progression of colorectal cancer.

Dietary habits affect fatty acid composition of visceral adipose tissue in subjects with colorectal cancer or obesity

PURPOSE

Aim of this study was to identify a possible relationship among dietary fatty acids (FA) intake, FA adipose tissue (AT) profile and cancer condition in lean vs obese subjects affected or not by colorectal cancer (CRC). Actually, inadequate dietary habits together with physical inactivity are primary determinants of obesity and cancer risk. Changes in lipid metabolism play a crucial role in different types of cancer and key enzymes involved in lipid-metabolic pathways, such as stearoyl-coA-desaturase 1 (SCD-1), are differentially expressed in normal and cancer tissues.

METHODS

Food frequency questionnaires (FFQ) were analyzed by Winfood software. FA were assessed by gas-liquid chromatography in visceral AT samples. Estimated desaturase activities were calculated as precursor FA/product FA ratio. Desaturase gene expressions were evaluated by RT-qPCR.

RESULTS

Lean and obese CRC subjects showed inadequate dietary habits. In particular, lean CRC subjects showed increase in the intake of saturated FA, specifically palmitic (p = 0.0042) and stearic acid (p = 0.0091), and a corresponding reduction of monounsaturated FA consumption, in particular oleic acid (p = 0.002) with respect to lean without CRC. Estimated SCD-1 activity in AT was increased in all the groups vs lean without CRC (pANOVA = 0.029).

CONCLUSIONS

Unhealthy eating habits, characterizing obese and CRC subjects, may influence the visceral AT profile and contribute to the alteration of the metabolic pathways. The quality of the diet, other than the quantity, can have a main role in the establishment of inflammatory microenvironment and in metabolic changes favouring CRC.

Dietary Factors in Sulfur Metabolism and Pathogenesis of Ulcerative Colitis

The biogeography of inflammation in ulcerative colitis (UC) suggests a proximal to distal concentration gradient of a toxin. Hydrogen sulfide (H₂S) has long been considered one such toxin candidate, and dietary sulfur along with the abundance of sulfate reducing bacteria (SRB) were considered the primary determinants of H₂S production and clinical course of UC. The metabolic milieu in the lumen of the colon, however, is the result of a multitude of factors beyond dietary sulfur intake and SRB abundance. Here we present an updated formulation of the H₂S toxin hypothesis for UC pathogenesis, which strives to incorporate the interdependency of diet composition and the metabolic activity of the entire colon microbial community. Specifically, we suggest that the increasing severity of inflammation along the proximal-to-distal axis in UC is due to the dilution of beneficial factors, concentration of toxic factors, and changing detoxification capacity of the host, all of which are intimately linked to the nutrient flow from the diet.

n-6 Linoleic Acid Induces Epigenetics Alterations Associated with Colonic Inflammation and Cancer

The farnesoid-X-receptor (FXR) protects against inflammation and cancer of the colon through maintenance of intestinal bile acid (BA) homeostasis. Conversely, higher levels of BA and cyclooxygenase-2 (COX-2) are risk factors for inflammation and cancer of the colon. In the United States, n-6 linoleic acid (LA) is the most commonly used dietary vegetable fat. Metabolism of n-6 fatty acids has been linked to a higher risk of intestinal cancer. The objectives of this study were to investigate in colonic mucosa the effects of a high-fat diet rich in LA (n-6HFD) on CpG methylation of Fxr and prostaglandin-endoperoxide synthase-2 (Ptsg-2) genes, and the impact on the expression of tumor suppressor adenomatous polyposis Coli (Apc) and proliferative cyclin D1 (Ccnd1) genes. Weaned C57BL/6J male mice were fed for 6 weeks either an n-6HFD containing 44% energy (44%E) from 22% safflower oil (SO, 76% LA by weight) or a 13% energy (13%E) control diet (Control) from SO (5% by weight). Mice fed the n-6HFD had reduced (60%) Fxr promoter CpG methylation and increased (~50%) Fxr mRNA. The expression of FXR-target ileal bile acid-binding protein (Ibabp), small heterodimer protein (Shp), and anti-inflammatory peroxisome proliferator-activated-γ1 genes was increased. The n-6HFD reduced Ptgs-2 CpG methylation, increased the expression of Cox-2, and increased Apc CpG methylation in colonic mucosa. Accordingly, reduced expression of Apc was coupled to accumulation of c-JUN and Ccnd1, respectively cofactor and gene targets for the β-catenin/Wnt signaling pathway. Finally, the n-6HFD reduced the expression of histone deacetylase-1 while favoring the accumulation of acetylated histone 3. We conclude that an n-6HFD epigenetically modifies Fxr, leading to the activation of downstream factors that participate in BA homeostasis. However, epigenetic activation of Ptsg-2 coupled with silencing of Apc and accumulation of C-JUN and Ccnd1 may increase the risk of inflammation and cancer of the colon.

Orientin, a flavanoid, mitigates 1, 2 dimethylhydrazine-induced colorectal lesions in Wistar rats fed a high-fat diet

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DMH induced preneoplastic lesions in colonic mucosa.

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Orientin treatment reduced DMH induction of cytochrome P450.

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Orientin attenuates DMH induced aberrant crypt formation.

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Orientin suppresses colonic tumor cell proliferation.

Orientin, a c- glycosyl flavonoid found copiously in roobios tea and various medicinal plants is well known for its antioxidant, anti-inflammatory, and antitumor effects. The present study aims to investigate the anti-cancer efficacy of orientin on 1,2 dimethyl hydrazine induced colonic aberrant crypt foci (ACF) and cell proliferation in Wistar rats. Rats were randomly divided into six groups and fed with high fat diet. Group 1 left as untreated control. Group 2 administered with DMH (20 mg/kg body weight) for initial 4 weeks and left untreated. Group 3 received orientin (10 mg/kg body weight) alone for the entire period. Group 4 received orientin along with DMH for initial 4 weeks and left untreated; Group 5 administered DMH for initial 4 weeks and treated with orientin for remaining 12 weeks; Group 6 administered DMH and treated with orientin throughout the entire period. Our preclinical findings suggest that the administration of orientin decreases the occurrence of DMH induced colonic polyps and aberrant crypt foci, augments antioxidant defense and altered the activities of drug metabolizing phase I and phase II enzymes in colonic and hepatic tissues and thereby ensuring the detoxification of carcinogen. Furthermore, orientin attenuates the aberrant crypt foci formation and reinstates the DMH induced cell proliferation, as evident from the AgNORs staining of colonic tissues of experimental rats. Thus, our study emphasizes that orientin may prevent DMH induced precancerous lesions and proven to be a potent antioxidant and antiproliferative agent.

Microbial Changes and Host Response in F344 Rat Colon Depending on Sex and Age Following a High-Fat Diet

Gut microbiota, an important component that affects host health, change rapidly and directly in response to altered diet composition. Recently, the role of diet–microbiome interaction on the development of colon cancer has been the focus of interest. Colon cancer occurs more frequently in an aged population, and in males. However, the effect of dietary changes on the gut microbiome has been studied mainly in young males, even though it may vary with age and sex. The aim of this study was to investigate microbial changes and host response in the colons of male and female 6-week-old (young) and 2-year-old (old) Fisher-344 rats exposed to a high-fat diet (HFD). Our results showed that exposure to HFD for 8 weeks decreased the species richness of microbiota (Chao1) and increased Firmicutes/Bacteroidetes ratio only in aged rats, and not in young rats. Sex differences underlying the alteration by HFD in the gut microbiome were observed in the microbiome of aged rats. For instance, the abundance ratio of Akkermansia muciniphila and Desulfovibrio spp. increased in response to HFD in young rats and female aged rats, but not in male aged rats. Histological inflammation and cell proliferation of colon mucosa (indexed by Ki67) were significantly increased by HFD even in young rats; aged rats showed significantly higher cell proliferation in the HFD group than in the control. The HFD-induced decrease of species richness and the increase in specific species (Desulfovibrio spp. and Clostridium lavalense), which produce carcinogenic compounds such as H₂S and N-nitroso compounds, were significantly correlated with Ki67 index. In colon mucosa, the concentration of myeloperoxidase was increased by HFD only in males, and not in females. In conclusion, the results suggest a link between HFD-induced gut dysbiosis (particularly the low species richness and high abundance ratios of Desulfovibrio spp. and C. lavalense) and cell proliferation of colon mucosa (indicated by Ki67 IHC). In addition, sex differences influence the response of gut microbiome to HFD particularly in old age. Such sex differences in the gut microbiota might be related to sex differences in inflammation in the colon mucosa.

High-fat diet modifies expression of hepatic cellular senescence gene p16(INK4a) through chromatin modifications in adult male rats

Background

Liver is the crucial organ as a hub for metabolic reactions. p16(INK4a) is a well-established cyclin-dependent kinase (CDK) inhibitor that plays important role in the molecular pathways of senescence, which lead to irreversible cell cycle arrest with secretion of proinflammatory cytokines and mitochondrial dysfunction. This study tested the hypothesis that cellular senescence regulated by p16(INK4a) is associated with high-fat diet in adult male rats.

Methods

Sprague Dawley rats were fed a high-fat (HF) diet or a control (C) diet for 9 weeks after weaning. At 12 weeks of age, liver samples of male rats were collected to investigate the key genes and liver physiological status.

Results

Both mRNA and protein expression level of cellular senescence marker, p16(INK4a), was increased significantly in HF group when compared to C group. A decrease of tri-methylated histone H3 lysine 27 (H3K27Me3) in the coding region of p16(INK4a) was observed. On the other hand, mRNA and protein expression of another inhibitor of cyclin-dependent kinase, p21(Cip1), was decreased significantly in HF group; however, no significant chromatin modification was found in this gene. Histological analysis demonstrated hepatic steatosis in HF group as well as severe fat accumulation.

Conclusions

Our study demonstrated that HF diet regulated cellular senescence marker p16(INK4a) through chromatin modifications, which may promote hepatic fat accumulation and steatosis.

Effect of eriodictyol on preneoplastic lesions, oxidative stress and bacterial enzymes in 1,2-dimethyl hydrazine-induced colon carcinogenesis

Eriodictyol, one of the strong flavonoids extracted from Eriodictyon californicum, is known for its antioxidant and anticarcinogenic properties. We estimated the chemopreventive effect of eriodictyol on 1,2 dimethylhydrazine (DMH)-induced experimental colon carcinogenesis in male albino Wistar rats. The rats were randomized into six groups. Our results evaluated the effect of eriodictyol supplementation (200 μg per kg b.w.) on DMH (20 mg per kg b.w)-induced rats (Groups 4-6). The incidence of polyps, aberrant crypt foci (ACF) and the lipid peroxidation levels were significantly decreased as compared to those in the DMH-alone treated rats (Group 2). In eriodictyol-supplemented DMH-treated rats, we observed increased activity of enzymatic and non-enzymatic antioxidants in the circulatory system, liver, and colon. The bacterial enzymes activities of mucosa and faecal were significantly decreased in the group with treatment of eriodictyol on DMH-induced rats. Moreover, in the eriodictyol-supplemented DMH-exposed rats, we observed reduced malignant glands of a histopathological appearance in both liver and colon tissue. Furthermore, we also observed reduced AgNORs counts of eriodictyol supplemented to the DMH-exposed rats. Therefore, we can conclude that eriodictyol can be used as an effective chemopreventive agent against DMH-induced colon carcinogenesis in experimental animal models.

Starch-enriched diet modulates the glucidic profile in the rat colonic mucosa

PURPOSE

The protective function of the intestinal mucosa largely depends on carbohydrate moieties that as a part of glycoproteins and glycolipids form the epithelial glycocalyx or are secreted as mucins. Modifications of their expression can be induced by an altered intestinal microenvironment and have been associated with inflammatory disorders and colorectal cancer. Given the influence of dietary factors on the gut ecosystem, here we have investigated whether a long term feeding on a starch-rich diet can modulate the glucidic profile in the colonic mucosa of rats.

METHODS

Animals were divided into two groups and maintained for 9 months at different diets: one group was fed a standard diet, the second was fed a starch-enriched diet. Samples of colonic mucosa, divided in proximal and distal portions, were processed for microscopic analysis. Conventional stainings and lectin histochemistry were applied to identify acidic glycoconjugates and specific sugar residues in oligosaccharide chains, respectively. Some lectins were applied on adjacent sections after sialidase/fucosidase digestion, deacetylation, and oxidation to characterize either terminal dimers or sialic acid acetylation.

RESULTS

An increase in sulfomucins was found to be associated with the starch-enriched diet that affected also the expression of several sugar residues as well as fucosylated and sialylated sequences in both proximal and distal colon.

CONCLUSIONS

Although the mechanisms leading to such a modulation are at present unknown, either an altered intestinal microbiota or a dysregulation of glycosylation patterns might be responsible for the types and distribution of changes in the glucidic profile here observed.

Dietary intake alters gene expression in colon tissue: possible underlying mechanism for the influence of diet on disease

Supplemental Digital Content is available in the text.

Background

Although the association between diet and disease is well documented, the biologic mechanisms involved have not been entirely elucidated. In this study, we evaluate how dietary intake influences gene expression to better understand the underlying mechanisms through which diet operates.

Methods

We used data from 144 individuals who had comprehensive dietary intake and gene expression data from RNAseq using normal colonic mucosa. Using the DESeq2 statistical package, we identified genes that showed statistically significant differences in expression between individuals in high-intake and low-intake categories for several dietary variables of interest adjusting for age and sex. We examined total calories, total fats, vegetable protein, animal protein, carbohydrates, trans-fatty acids, mutagen index, red meat, processed meat, whole grains, vegetables, fruits, fiber, folate, dairy products, calcium, and prudent and western dietary patterns.

Results

Using a false discovery rate of less than 0.1, meat-related foods were statistically associated with 68 dysregulated genes, calcium with three dysregulated genes, folate with four dysregulated genes, and nonmeat-related foods with 65 dysregulated genes. With a more stringent false discovery rate of less than 0.05, there were nine meat-related dysregulated genes and 23 nonmeat-related genes. Ingenuity pathway analysis identified three major networks among genes identified as dysregulated with respect to meat-related dietary variables and three networks among genes identified as dysregulated with respect to nonmeat-related variables. The top networks (Ingenuity Pathway Analysis network score >30) associated with meat-related genes were (i) cancer, organismal injury, and abnormalities, tumor morphology, and (ii) cellular function and maintenance, cellular movement, cell death, and survival. Among genes related to nonmeat consumption variables, the top networks were (i) hematological system development and function, nervous system development and function, tissue morphology and (ii) connective tissue disorders, organismal injury, and abnormalities.

Conclusion

Several dietary factors were associated with gene expression in our data. These findings provide insight into the possible mechanisms by which diet may influence disease processes.

The Impact of Dietary Energy Intake Early in Life on the Colonic Microbiota of Adult Mice

The complex and dynamic interactions between diet, gut microbiota (GM) structure and function, and colon carcinogenesis are only beginning to be elucidated. We examined the colonic microbiota and aberrant crypt foci (ACF) in C57BL/6N female mice fed various dietary interventions (control, energy restricted and high-fat) provided during two phases (initiation and progression) of azoxymethane (AOM)-induced early colon carcinogenesis. During progression (wks. 22–60), a high-fat diet enhanced ACF formation compared to a control or energy restricted diet. In contrast, energy restriction during initiation phase (wks. 3–21) enhanced ACF burden at 60 weeks, regardless of the diet in progression phase. Alterations in GM structure during the initiation phase diet were partially maintained after changing diets during the progression phase. However, diet during the progression phase had major effects on the mucosal GM. Energy restriction in the progression phase increased Firmicutes and reduced Bacteroidetes compared to a high-fat diet, regardless of initiation phase diet, suggesting that diet may have both transient effects as well as a lasting impact on GM composition. Integration of early life and adult dietary impacts on the colonic microbial structure and function with host molecular processes involved in colon carcinogenesis will be key to defining preventive strategies.

Involuntary wheel running improves but does not fully reverse the deterioration of bone structure of obese rats despite decreasing adiposity

This study investigated whether exercise or antioxidant supplementation with vitamin C and E during exercise affects bone structure and markers of bone metabolism in obese rat. Sprague-Dawley rats, 6-week old, were fed a normal-fat diet (NF, 10 % kcal as fat) and a high-fat diet (HF, 45 % with extra fat from lard) ad libitum for 14 weeks. Then, rats on the high-fat diet were assigned randomly to three treatment groups for additional 12 weeks with forced exercise: HF; HF + exercise (HF + Ex); and HF with vitamin C (0.5 g ascorbate/kg diet) and vitamin E (0.4 g α-tocopherol acetate/kg diet) supplementation + exercise (HF + Ex + VCE). At the end of the study, body weight and fat (%) were similar among NF, HF + Ex, and HF + Ex + VCE, whereas HF had greater body weight and fat (%) than other groups. Compared to NF, HF had elevated serum leptin, tartrate-resistant acid phosphatase (TRAP), and IGF-1; increased trabecular separation and structural model index; and lowered bone mineral density, trabecular connectivity density, and trabecular number in distal femur, while HF + Ex and HF + Ex + VCE had elevated serum TRAP and decreased bone volume/total volume and trabecular number of distal femurs. Compared to HF, HF + Ex and HF + Ex + VCE had decreased serum TRAP and osteocalcin and improved bone structural properties of the distal femur. These findings suggest that exercise, while decreasing body fat, does not fully protect against the negative skeletal effects of existing obesity induced by a high-fat diet. Furthermore, vitamin C and E supplementation has no additional benefits on bone structural properties during exercise.