Progression Of Colitis-associated Colorectal Cancer Research Articles

Advancements of Macrophages Involvement in Pathological Progression of Colitis-Associated Colorectal Cancer and Associated Pharmacological Interventions.

Intestinal macrophages play crucial roles in both intestinal inflammation and immune homeostasis. They can adopt two distinct phenotypes, primarily determined by environmental cues. These phenotypes encompass the classically activated pro-inflammatory M1 phenotype, as well as the alternatively activated anti-inflammatory M2 phenotype. In regular conditions, intestinal macrophages serve to shield the gut from inflammatory harm. However, when a combination of genetic and environmental elements influences the polarization of these macrophages, it can result in an M1/M2 macrophage activation imbalance, subsequently leading to a loss of control over intestinal inflammation. This shift transforms normal inflammatory responses into pathological damage within the intestines. In patients with ulcerative colitis-associated colorectal cancer (UC-CRC), disorders related to intestinal inflammation are closely correlated with an imbalance in the polarization of intestinal M1/M2 macrophages. Therefore, reinstating the equilibrium in M1/M2 macrophage polarization could potentially serve as an effective approach to the prevention and treatment of UC-CRC. This paper aims to scrutinize the clinical evidence regarding Chinese medicine (CM) in the treatment of UC-CRC, the pivotal role of macrophage polarization in UC-CRC pathogenesis, and the potential mechanisms through which CM regulates macrophage polarization to address UC-CRC. Our objective is to offer fresh perspectives for clinical application, fundamental research, and pharmaceutical advancement in UC-CRC.

Mechanic Evaluation of Wu-Mei-Pill on Colitis-Associated Colorectal Cancer: An Integrated Transcriptomics, Metabolomics, and Experimental Validation Study

BackgroundChronic intestinal inflammatory diseases play a crucial role in the onset of colorectal cancer (CRC). Effectively impeding the progression of colitis-associated colorectal cancer (CAC) can be instrumental in hindering CRC development. Wu-Mei-Pill (WMP), a formulation comprising various herbal extracts, is clinically employed for CAC treatment, yet the underlying mechanism of WMP's efficacy in CAC remains unclear. Our study firstly demonstrated the effects and mechanisms of WMP on transcriptional and metabolic levels based on integrated transcriptomics and untargeted metabolomics and relative experimental validations. Materials and MethodsA CAC mouse model was established through a single injection of azoxymethane (AOM) followed by intermittent dextran sodium sulfate (DSS) intervention, with subsequent WMP administration. Initially, the therapeutic impact of WMP on the CAC model was assessed by observing survival rate, body weight change, colon length, tumor number, tumor load, and pathological changes in the colon tissue of CAC mice post-WMP intervention. Subsequently, differential genes and metabolites in the colorectal tissue of CAC mice following WMP intervention were identified through transcriptomics and non-targeted metabolomics. Finally, the influence of WMP on the peroxisome proliferator activated receptor (PPAR) pathway, Wnt pathway, and C-C motif chemokine ligand 3 (CCL3)/ C-C motif chemokine receptor 1 (CCR1) axis in CAC mice was verified through western blot, immunofluorescence, and ELISA based on the results of transcriptomics and non-targeted metabolomics. ResultsWMP intervention enhanced survival, alleviated body weight loss, shortened colon length, tumor occurrence, and pathological changes in the colorectal tissue of CAC mice, such as glandular damage, tumourigenesis, and inflammatory cell infiltration. Transcriptomic and non-targeted metabolomic results revealed that WMP intervention up-regulated the expression of key regulatory mechanisms of fatty acid oxidation PPAR pathway-related genes (Pparg, Ppara, Cpt1a, and Acadm) and metabolites (L-carnitine and L-palmitoylcarnitine). Additionally, it down-regulated Wnt pathway-related genes (Wnt3, Axin2, Tcf7, Mmp7, Lgr5, Wnt5a, Fzd6, Wnt7b, Lef1, and Fzd10 etc.) and pro-inflammatory related genes (Il1b, Il6, Il17a, Ccl3, and Ccr1 etc.). Experimental validation demonstrated that WMP up-regulated PPAR pathway-related proteins [PPARγ, PPARα, carnitine palmitoyltransferase 1A (CPT1A), and acyl-CoA dehydrogenase medium chain (ACADM)] in the colorectal tissue of CAC mice. It also down-regulated Wnt pathway-related proteins [β-catenin, T-cell factor (TCF), lymphoid enhancer-binding factor (LEF), and matrix metallopeptidase 7 (MMP7)], inhibited the nuclear translocation of the key transcription factor β-catenin in the Wnt pathway, and suppressed epithelial-to-mesenchymal transition (EMT) activation induced by the Wnt pathway (up-regulated E-cadherin and down-regulated Vimentin). Furthermore, WMP intervention reduced pro-inflammatory factors [interleukin (IL)-6, IL-1β, and IL-17A] and decreased CCL3/CCR1 axis factors, including CCL3 protein levels and diminished F4/80+CCR1+ positive expressed cells. ConclusionWMP significantly inhibits CAC tumorigenesis by up-regulating PPARα-mediated fatty acid oxidation, inhibiting the Wnt signaling pathway-mediated EMT, and suppressing CCL3/CCR1-mediated inflammatory responses.

Intestinal epithelial SNAI1 promotes the occurrence of colorectal cancer by enhancing EMT and Wnt/β-catenin signaling.

Colorectal cancer (CRC) is a prevalent cause of cancer and mortality on a global scale. SNAI1, a member of the zinc finger transcription superfamily, is a significant contributor to embryonic development and carcinogenesis through the process of epithelial-mesenchymal transition (EMT). While prior research utilizing CRC cells and clinical data has demonstrated that SNAI1 facilitates CRC progression through diverse mechanisms, the precise manner in which epithelial SNAI1 regulates CRC development in vivo remains unclear. In this study, colitis and colitis-associated CRC were induced through the use of intestinal epithelium-specific Snai1 knockout (Snai1 cKO) mice. Our findings indicate that Snai1 cKO mice exhibit a reduced susceptibility to acute colitis and colitis-associated CRC compared to control mice. Western-blot analysis of colon tissues revealed that Snai1 cKO mice exhibited a higher overall apoptosis level during tumor formation than control mice. No significant differences were observed in the activation of the classical p53 signaling pathway. However, Snai1 cKO mice exhibited weakened EMT and Wnt/β-catenin pathway activation. In summary, our study has provided evidence in vivo that the intestinal epithelial SNAI1 protein suppresses apoptosis, amplifies the EMT, and activates the Wnt/β-catenin signaling pathways in both early and late phases of CRC formation, thus promoting the development and progression of colitis-associated CRC.

Deletion of TNF in Winnie-APCMin/+ Mice Reveals Its Dual Role in the Onset and Progression of Colitis-Associated Colorectal Cancer.

Colorectal cancer (CRC) is among the best examples for depicting the relationship between inflammation and cancer. The introduction of new therapeutics targeting inflammatory mediators showed a marked decrease in the overall risk of CRC, although their chemopreventive potential is still debated. Specifically, a monoclonal antibody that blocks tumor necrosis factor (TNF), infliximab, increases CRC risk in inflammatory bowel disease patients. To address the axis between TNF and CRC development and progression, we depleted the Tnf from our previously established murine model of colitis-associated cancer (CAC), the Winnie-ApcMin/+ line. We characterized the new Winnie-APCMin/+-TNF-KO line through macroscopical and microscopical analyses. Surprisingly, the latter demonstrated that the deletion of Tnf in Winnie-ApcMin/+ mice resulted in an initial reduction in dysplastic lesion incidence in 5-week-old mice followed by a faster disease progression at 8 weeks. Histological data were confirmed by the molecular profiling obtained from both the real-time PCR analysis of the whole tissue and the RNA sequencing of the macrodissected tumoral lesions from Winnie-APCMin/+-TNF-KO distal colon at 8 weeks. Our results highlight that TNF could exert a dual role in CAC, supporting the promotion of neoplastic lesions onset in the early stage of the disease while inducing their reduction during disease progression.

The negative effect of Akkermansia muciniphila-mediated post-antibiotic reconstitution of the gut microbiota on the development of colitis-associated colorectal cancer in mice.

The bidirectional relationship between colorectal cancer (CRC) and the gut microbiome has been well-documented. Here, we investigated the impact of Akkermansia muciniphila-mediated post-antibiotic gut microbial reconstitution on the development of colitis-associated CRC (CAC). The results showed that post-antibiotic replenishment of A. muciniphila worsened the tumorigenesis of CAC as indicated by increased number of large (>2 mm in diameter) tumors and both average and total tumor diameters. Measures of intestinal barrier function showed that post-antibiotic A. muciniphila gavage damaged the intestinal barrier as reflected by lower transcriptional levels of Tjp1, Ocln, Cdh1, and MUC2. Impaired gut barrier was followed by lipopolysaccharides (LPS) translocation as indicated by higher level of serum LPS-binding protein (LBP). The increased colonic mRNA levels of Il1b, Il6, and Tnfa and serum levels of IL-1β, IL-6, and TNF-α indicated that post-antibiotic A. muciniphila replenishment resulted in overactivated inflammatory environment in CAC. The analysis of the evolution of the microbial community during the progression of CAC showed that post-antibiotic supplementation of A. muciniphila led to a distinct microbial configuration when compared with other treatments characterized by enriched Firmicutes, Lachnospiraceae, and Ruminococcaceae, and depleted Bacteroidetes, which was accompanied by higher Firmicutes/Bacteroidetes (F/B) ratio. Furthermore, post-antibiotic A. muciniphila administration changed the bile acid (BA) metabolic profile as indicated by decreased concentrations of secondary BA (SBA), ω–murocholic acid (ωMCA), and murocholic acid (muroCA). In addition, the A. muciniphila supplementation after antibiotic pretreatment also impacted the metabolism of short-chain fatty acids (SCFAs) as evidenced by increased concentrations of acetic acid, propionic acid, butyric acid, and valeric acid. Our study surprisingly observed that A. muciniphila-mediated post-antibiotic reconstitution of the gut microbiota aggravated the CAC in mice. It might exert its effect by damaging the gut barrier, exacerbating inflammatory responses, disrupting the post-antibiotic recovery of the microbial community, and further influencing the metabolism of BA and SCFAs. These findings indicated that maintaining the homeostasis of intestinal microorganisms is more crucial to health than replenishing a single beneficial microbe, and probiotics should be used with caution after antibiotic treatment.

The P2X7 Receptor Promotes Colorectal Inflammation and Tumorigenesis by Modulating Gut Microbiota and the Inflammasome.

Background: Given the role of the P2X7 receptor (P2X7R) in inflammatory bowel diseases (IBD), we investigated its role in the development and progression of colitis-associated colorectal cancer (CA-CRC). Methods: CA-CRC was induced in P2X7R+/+ and P2X7R−/− mice with azoxymethane (AOM) combined with dextran sodium sulfate (DSS). In a therapeutic protocol, P2X7R+/+ mice were treated with a P2X7R-selective inhibitor (A740003). Mice were evaluated with follow-up video endoscopy with endoluminal ultrasound biomicroscopy. Colon tissue was analyzed for histological changes, densities of immune cells, expression of transcription factors, cytokines, genes, DNA methylation, and microbiome composition of fecal samples by sequencing for 16S rRNA. Results: The P2X7R+/+ mice displayed more ulcers, tumors, and greater wall thickness, than the P2X7R−/− and the P2X7R+/+ mice treated with A740003. The P2X7R+/+ mice showed increased accumulation of immune cells, production of proinflammatory cytokines, activation of intracellular signaling pathways, and upregulation of NLRP3 and NLRP12 genes, stabilized after the P2X7R-blockade. Microbial changes were observed in the P2X7R−/− and P2X7R+/+-induced mice, partially reversed by the A740003 treatment. Conclusions: Regulatory mechanisms activated downstream of the P2X7R in combination with signals from a dysbiotic microbiota result in the activation of intracellular signaling pathways and the inflammasome, amplifying the inflammatory response and promoting CA-CRC development.

Huangqin Tang Interference With Colitis Associated Colorectal Cancer Through Regulation of Epithelial Mesenchymal Transition and Cell Cycle.

Background: Although the exact molecular mechanisms of colitis-associated colorectal cancer are not fully understood, the chronic inflammation was positively correlated with tumorigenesis. The traditional Chinese medicine botanical formulation Huangqin Tang has significant anti-inflammatory effects. We investigated whether HQT can ameliorate the progression of inflammation to cancer through its anti-inflammatory effects by using relevant predictions and experiments. Methods: We used the azoxymethane/dextran sodium sulfate method to induce the mice colitis-associated colorectal cancer model. After preventive administration of Huangqin Tang to the mice model, colonic tissues were taken for quantitative proteomic analysis of tandem mass tags, and the proteomic results were then experimentally validated using the molecular biology approach. Results: Proteomic screening revealed that the effect of the mechanism of Huangqin-Tang on the colitis-associated colorectal cancer mice model may be related to infinite replication which demonstrated abnormal G1/S checkpoint and epithelial mesenchymal transition acceleration. The levels of inflammatory factors such as interleukin-1α, interleukin-1β, interleukin-6, and tumor necrosis factor-α were significantly reduced in colitis-associated colorectal cancer mice treated with Huangqin Tang; the aberrant expression of G1/S checkpoint-associated sites of cell cycle protein-dependent kinase 4, D1-type cyclins, and dysregulation of related sites of the WNT pathway which are most related to the acceleration of the epithelial mesenchymal transition process including WNT3A, β-catenin, E-cadherin, and glycogen synthase kinase 3β has been improved. Conclusion: Reducing inflammation and thus inhibiting the progression of colitis-associated colorectal cancer by using Huangqin-Tang is effective, and the mechanism of action may be related to the inhibition of uncontrolled proliferation during tumorigenesis. In the follow-up, we will conduct a more in-depth study on the relevant mechanism of action.

Xanthine oxidoreductase promotes the progression of colitis-associated colorectal cancer by causing DNA damage and mediating macrophage M1 polarization

In addition to its pivotal role in purine metabolism, xanthine oxidoreductase (XOR) is one of the key enzymes involved in superoxide radical generation. Oxidative stress has been implicated in the etiology of colorectal cancer, but the contribution of XOR remains unclear. Here we investigated the role of XOR in colitis-associated colorectal cancer (CAC) and the underlying mechanisms. Using clinical samples, we demonstrated that XOR up-regulation was an early event in colonic carcinogenesis. Pharmacological inhibition of XOR effectively delayed the progression of CAC. Moreover, XOR activity positively correlated with tumor necrosis factor-alpha (TNFα) protein levels. Mechanistically, TNFα may activate XOR transcription via activator protein-1 and, thus, promote endogenous hydrogen peroxide generation, resulting in oxidative DNA damage in colon cancer cells. On the other hand, XOR may regulate the TNFα mRNA transcripts by mediating LPS-induced macrophage M1 polarization. Collectively, XOR promotes tumor development by programming the tumor microenvironment and stimulates CAC progression via DNA damage-induced genetic instability.

Fusobacterium nucleatum Accelerates the Progression of Colitis-Associated Colorectal Cancer by Promoting EMT

Simple SummaryColitis-associated cancer (CAC) are associated with the development and progression of colorectal cancer (CRC). And Fusobacterium nucleatum (F. nucleatum), a major pathogen involved in chronic periodontitis, may play an important role in CRC progression. Though the importance of F. nucleatum in CRC has attracted attention, its exact role and related mechanism in CAC progression remain unclear. We investigated the effects of F. nucleatum in both in vitro and in vivo colitis models induced with dextran sodium sulfate (DSS), a well-known colitis-inducing chemical, on the aggressiveness of CAC and its related mechanism. This study showed that F. nucleatum accelerates the progression of CAC cancer by promoting epithelial–mesenchymal transition (EMT). This study provides a novel mechanism involved F. nucleatum in the development of colitis-associated CRC.Recently, it has been reported that Fusobacterium nucleatum, a major pathogen involved in chronic periodontitis, may play an important role in colorectal cancer (CRC) progression. In addition, inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease represent major predisposing conditions for the development of CRC, and this subtype of cancer is called colitis-associated cancer (CAC). Although the importance of F. nucleatum in CRC has attracted attention, its exact role and related mechanism in CAC progression remain unclear. In this study, we investigated the effects of F. nucleatum in experimental colitis induced with dextran sodium sulfate (DSS), which is a well-known colitis-inducing chemical, on the aggressiveness of CAC and its related mechanism in both in vitro and in vivo models. F. nucleatum synergistically increased the aggressiveness and epithelial–mesenchymal transition (EMT) characteristics of CRC cells that were treated with DSS compared to those in non-treated CRC cells. The role of F. nucleatum in CAC progression was further confirmed in mouse models, as F. nucleatum was found to significantly increase the malignancy of azoxymethane (AOM)/DSS-induced colon cancer. This promoting effect of F. nucleatum was based on activation of the EGFR signaling pathways, including protein kinase B (AKT) and extracellular signal-regulated kinase (ERK), and epidermal growth factor receptor (EGFR) inhibition significantly reduced the F. nucleatum-induced EMT alteration. In conclusion, F. nucleatum accelerates the progression of CAC by promoting EMT through the EGFR signaling pathway.

Dietary Supplementation of Foxtail Millet Ameliorates Colitis-Associated Colorectal Cancer in Mice via Activation of Gut Receptors and Suppression of the STAT3 Pathway.

Coarse cereal intake has been reported to be associated with reduced risk of colorectal cancer. However, evidence from intervention studies is absent and the molecular basis of this phenomenon remains largely unexplored. This study sought to investigate the effects of foxtail millet and rice, two common staple grains in Asia, on the progression of colitis-associated colorectal cancer (CAC) and define the mechanism involved. In total, 40 BALB/c mice were randomized into four groups. The Normal and azoxymethane/dextran sodium sulfate (AOM/DSS) groups were supplied with an AIN-93G diet, while the millet- and rice-treated groups were supplied with a modified AIN-93G diet. Compared to the AOM/DSS-induced CAC mice supplemented with rice, an increased survival rate, suppressed tumor burden, and reduced disease activity index were observed in the millet-treated group. The levels of IL-6 and IL-17 were decreased in the millet-treated group compared to both the AOM/DSS and AOM/DSS + rice groups. Millet treatment inhibited the phosphorylation of STAT3 and the related signaling proteins involved in cell proliferation, survival and angiogenesis. These beneficial effects were mediated by the activation of gut receptors AHR and GPCRs via the microbial metabolites (indole derivates and short-chain fatty acids) of foxtail millet. Moreover, millet-treatment increased the abundance of Bifidobacterium and Bacteroidales_S24-7 compared to the rice-treated mice. This study could help researchers to develop better dietary patterns that work against inflammatory bowel disease (IBD) and for CAC patients.

A Grape Powder Attenuates Colonic Inflammation, Inhibits Colitis-associated Colorectal Cancer Development and Causes Favorable Changes of Gut Microbiota in Mice (OR04-07-19)

ObjectivesRecent discoveries suggest that gut microbiota is involved in the progression of colitis-associated colorectal cancer (CAC) and natural products like polyphenols can modulate gut microbiota. Polyphenol components of grape like resveratrol have been shown to have anti-colorectal cancer effects in animal models, but the underlying mechanism is not completely understood. The objective of this study is to examine the chemo-preventive effect of a whole grape powder (GP) on tumorigenesis in a mouse CAC model and evaluated the impact of GP on gut microbiota as a potential anti-CAC mechanism. To dissect the role of polyphenols in the GP, we compared GP at 3 and 10% diet to calorie, fiber, sugar and organic acid-matched placebo. MethodsWe used male Balb/c mice and divided them into diseased groups treated with azoxymethane (AOM) and dextran sodium sulfate (DSS) and healthy groups, both of which had placebo control diet, GP at 3% or 10% diet. To induce tumorigenesis, we injected AOM at 9.5 mg/kg bw at 6 weeks of age, followed by 2-cycle DSS (1.5% in drinking water). During the study, we monitored animals’ body weight and food consumption weekly, and evaluated their colitis symptoms during DSS treatments. All animals were sacrificed at 16 weeks of age and 24-hr accumulative fecal samples were collected prior to sacrifice for gut microbial analysis. ResultsCompared to the control diet, 10% GP diet alleviated colitis symptoms including rectal bleeding and diarrhea, and reduced total tumor multiplicity by 29% (P < 0.05). GP diet increased microbial alpha-diversity and significantly shifted the gut microbial composition in both healthy and diseased groups. Under both conditions, 10% GP diet increased the abundance of various taxa belonging to Lachnospiraceae family. Canonical correspondence analysis (CCA) of gut microbiota indicated that increased GP supplementation was associated with healthier animal status. In particular, we observed that the predicted functional profile of gut microbiota from diseased mice with 10% GP diet was similar to those from healthy mice with the control diet. Conclusions10% GP diet showed CAC chemo-preventive effects and modulated gut microbiota under both healthy and diseased conditions, and appeared to prevent CAC-associated gut microbiota changes. Funding SourcesCalifornia Table Grape Commission.

The germ-free mice monocolonization with Bacteroides fragilis improves azoxymethane/dextran sulfate sodium induced colitis-associated colorectal cancer

Objective: Inflammatory bowel disease (IBD) is generally considered as a major risk factor in the progression of colitis-associated colorectal cancer (CAC). Previous studies have indicated that the composition of gut microflora may be involved in CAC induction and progress. Bacteroides fragilis (BF) is a Gram-negative anaerobe belonging to colonic symbiotic bacteria of the host. This study was aimed to investigate the protective role of BF in a colorectal cancer (CRC) model induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) in germ-free (GF) mice.Materials and methods: Total 22 GF mice were divided into two groups: GF and BF group. Half of the GF mice were colonized with BF for 28 days before CRC induction by AOM/DSS.Results: BF colonization increased animal survival (100%). Cecum weight and cecum/body weight ratio significantly decreased in BF/AOM/DSS group. Interestingly, there was a significant decrease in tumor number and tumor incidence in the BF/AOM/DSS group as compared to the GF/AOM/DSS group. The adenocarcinoma/adenoma incidence and histologic score were also decreased in the BF/AOM/DSS group. In addition, immunohistochemistry staining found decreased numbers of cell proliferation (PCNA) and inflammatory cell (granulocytes) infiltration in the colon mucosa of the BF group. The β-catenin staining in the BF/AOM/DSS group had fewer and weaker positive signal expressions. Taking together, the BF colonization significantly ameliorated AOM/DSS-induced CRC by suppressing the activity of cell proliferation-related molecules and reducing the number of inflammatory cells.Conclusions: Symbiotic BF may play a pivotal role in maintaining the gastrointestinal immunophysiologic balance and regulating anti-tumorigenesis responses.

Increased Genetic Instability and Accelerated Progression of Colitis-Associated Colorectal Cancer through Intestinal Epithelium–specific Deletion of Klf4

Krüppel-like factor 4 (KLF4), a zinc finger transcription factor, regulates homeostasis of the intestinal epithelium. Previously, it was reported that KLF4 functions as a tumor suppressor in colorectal cancer. Here, evidence demonstrates that KLF4 mitigates the development and progression of colitis-associated colorectal cancer (CAC) in a murine model. Mice with intestinal epithelium-specific deletion of Klf4 (Klf4ΔIS ) and control mice (Klf4fl/fl ) were used to explore the role of KLF4 in the development of azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced CAC. Upon AOM and DSS treatment, KLF4 expression was progressively lost in colonic tissues of Klf4fl/fl mice during tumor development. Klf4ΔIS mice treated with AOM/DSS developed significantly more adenomatous polyps and carcinomas in situ in comparison with treated Klf4fl/fl mice. Adenomatous polyps, but not normal-appearing mucosa, from colonic tissues of treated Klf4ΔIS mice contained a significantly increased number of mitotic cells with more than 2 centrosomes relative to treated control mice. KLF4 and p53 colocalize to the centrosomes in mouse embryonic fibroblasts (MEF). Absence of KLF4 in Klf4-/- MEFs inhibits and its overexpression restores p53 localization to the centrosomes in Klf4-/- MEFs. IMPLICATIONS: Taken together, these results indicate that KLF4 plays a protective role against progression of CAC by guarding against genetic instability.

The Role of Curcumin in Modulating Colonic Microbiota During Colitis and Colon Cancer Prevention.

Intestinal microbiota influences the progression of colitis-associated colorectal cancer. With diet being a key determinant of the gut microbial ecology, dietary interventions are an attractive avenue for the prevention of colitis-associated colorectal cancer. Curcumin is the most active constituent of the ground rhizome of the Curcuma longa plant, which has been demonstrated to have anti-inflammatory, antioxidative, and antiproliferative properties. Il10 mice on 129/SvEv background were used as a model of colitis-associated colorectal cancer. Starting at 10 weeks of age, wild-type or Il10 mice received 6 weekly intraperitoneal injections of azoxymethane (AOM) or phosphate-buffered saline (PBS) and were started on either a control or a curcumin-supplemented diet. Stools were collected every 4 weeks for microbial community analysis. Mice were killed at 30 weeks of age. Curcumin-supplemented diet increased survival, decreased colon weight/length ratio, and, at 0.5%, entirely eliminated tumor burden. Although colonic histology indicated improvement with curcumin, no effects of mucosal immune responses have been observed in PBS/Il10 mice and limited effects were seen in AOM/Il10 mice. In wild-type and in Il10 mice, curcumin increased bacterial richness, prevented age-related decrease in alpha diversity, increased the relative abundance of Lactobacillales, and decreased Coriobacterales order. Taxonomic profile of AOM/Il10 mice receiving curcumin was more similar to those of wild-type mice than those fed control diet. In AOM/Il10 model, curcumin reduced or eliminated colonic tumor burden with limited effects on mucosal immune responses. The beneficial effect of curcumin on tumorigenesis was associated with the maintenance of a more diverse colonic microbial ecology.

Distribution of Bone-Marrow-Derived Endothelial and Immune Cells in a Murine Colitis-Associated Colorectal Cancer Model

Inflammatory bowel disease (IBD) can lead to an increased risk of developing colorectal cancer (CRC). The aim of this study was to establish a model for combined bone marrow transplantation (BMT) and colitis-associated colorectal cancer (CAC) and to define the contribution of BM-derived cells during the inflammation associated with carcinogenesis. We established a model for BMT using green fluorescent protein (GFP) transgenic mice, followed by AOM/DSS-induced CAC, and performed confocal microscopy analysis on in vivo living tissue and frozen tumor sections. Our imaging analyses showed that GFP-positive cells extensively infiltrated the tumor stroma and that some WGA and GFP or CD31 and GFP double-positive cells were observed in the lining of tumor vessels. Flow cytometry analysis of the tumor-infiltrating cells showed that the GFP-positive CD11c+ DCs cells were one-third of the GFP+/CD11C- cells, and that half of these DCs (0.96% vs 1.02%) were GFP-positive BM-derived cells. The majority of CD4+ T cells were GFP-negative (12.02% vs 1.9%), and we discovered a novel CD4+ CD11c+ DC subset (0.34% vs 1.64%). In conclusion, we defined the distribution of BM-derived endothelial cells, CD11c+ DCs and CD4+ T cells in tumors. This model might be useful for elucidating the diverse BM-derived cell types and functions during the progression of colitis-associated colorectal cancer.

Chemopreventive effect of dietary glutamine on colitis-associated colon tumorigenesis in mice

Chronic colonic inflammation is a known risk factor for colorectal cancer (CRC). Glutamine (GLN) supplementation has shown its anti-inflammation benefit in experimental colitis. Whether GLN is effective in preventing colon carcinogenesis remains to be investigated. The chemopreventive activity of GLN was evaluated in the mouse model of dextran sulfate sodium (DSS)/azoxymethane (AOM)-induced colitis-associated CRC in this study. Mice were treated with DSS/AOM and randomized to receive either a control diet or GLN-enriched diet intermittently of the study. The disease activity index was evaluated weekly. On day 80 of the experiment, the entire colon and rectum were processed for histopathologic examination and further evaluation. Pro-inflammatory mediators and cytokines were measured by enzyme-linked immunosorbent assay, real-time-PCR and western blot analysis. Here, we show that after GLN-enriched diet, the colitis presented a statistical improvement and tumors burden decreased significantly. This was accompanied by lower activity of nuclear factor-κB (NF-κB), decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase, lower expression of cytokines and chemokines as well as reduced proliferation and induced apoptosis in the colons of colitis-associated CRC mice. Our data demonstrate the protective/preventive effect of GLN in the progression of colitis-associated CRC, which was correlated with a dampening of inflammation and NF-κB activity and with a decrease of inflammatory protein overexpression.

Intestinal inflammation and colorectal cancer: a double-edged sword?

Chronic inflammation is thought to be the leading cause of many human cancers including colorectal cancer (CRC). Accordingly, epidemiologic and clinical studies indicate that patients affected by ulcerative colitis and Crohn's disease, the two major forms of inflammatory bowel disease, have an increased risk of developing CRC. In recent years, the role of immune cells and their products have been shown to be pivotal in initiation and progression of colitis-associated CRC. On the other hand, activation of the immune system has been shown to cause dysplastic cell elimination and cancer suppression in other settings. Clinical and experimental data herein reviewed, while confirming chronic inflammation as a risk factor for colon carcinogenesis, do not completely rule out the possibility that under certain conditions the chronic activation of the mucosal immune system might protect from colonic dysplasia.

Abstract 856: Association of high levels of folate with increased risk for colitis-associated colorectal neoplasia

Abstract Low folate levels are known to be a risk factor for multiple human diseases including colorectal cancer. However, the relationship between folate levels and the prevention or development of colorectal cancer remains controversial. Patients with ulcerative colitis often possess low levels of folate due to inadequate intake and malabsorption of nutrients. Thus, folic acid supplementation is highly recommended despite very limited information regarding the effect of folic acid on the progression of colitis-associated colorectal cancer. The major objectives of the present study are to evaluate folate levels during the progression of colitis-associated colon cancer and to assess the potential functional role of folic acid supplementation on the growth of colon cancer cells. To study the effect of inflammation on levels of folate, acute and chronic colitis were induced within the mouse colon by administering 2 cycles of 3% dextran sulfate sodium (DSS) following one injection of azoxymethane (AOM; 7.4 mg/kg); a regimen that ultimately leads to the formation of colitis-associated dysplasias and carcinomas. At 10+, 12 and 19 wks of age, corresponding to acute colitis, chronic colitis, and colitis-associated dysplasia, respectively, blood samples were collected retro-orbitally and plasma folate levels were measured using stable isotope dilution liquid chromatography-multiple reaction monitoring/mass spectrometry. At sacrifice, the histopathology of the colon was correlated with plasma folate levels. Levels of plasma folate were reduced 33% (78.4 + 7.2 nM vs. 116.2 + 15.6 nM, p&amp;lt;0.05) and 21% (110. 4 + 5.2 nM vs. 138.2 + 10.8 nM, p&amp;lt;0.05) in AOM/DSS-treated mice at 10+ or 12 wks of age, respectively, as compared to age-matched mice treated with AOM alone. Surprisingly, plasma folate levels were elevated 12% in AOM/DSS-treated mice exhibiting multiple colitis-associated dysplasias (19 wks of age), as compared to control mice without tumors treated with AOM only. Administration of 5-aminosalicylic acid (5-ASA) to colitic mice at 75 mg/kg, a dose that inhibits the multiplicity of dysplasias by 50%, decreased plasma folate to a level lower than that of AOM/DSS controls (77.9 +10.7 nM vs. 199.0 + 25.1 nM, p&amp;lt;0.001). The effect of folic acid supplementation on cellular signaling pathways was evaluated in SW480 colon carcinoma cells cultured in the presence of low- or high-dose folic acid. Western blot analyses using antibodies against phospho-ERK1/2 and phospho-GSK3β revealed that exposure to high-dose folic acid increased phosphorylated ERK1/2 and reduced phosphorylated GSK3β by 2.0- and 2.5-fold, respectively, as compared to cells exposed to low-dose folic acid. These in vitro and in vivo data, when combined, suggest that high levels of folic acid may increase risk for colitis-associated neoplasia via the ERK/MAPK and GSK3β pathways. Supported by NIH R01 CA124693. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 856. doi:10.1158/1538-7445.AM2011-856