Multiple Intestinal Neoplasia Mice Research Articles

Single-Cell Profiling Reveals the Impact of Genetic Alterations on the Differentiation of Inflammation-Induced Murine Colon Tumors.

Genetic mutations and chronic inflammation of the colon contribute to the development of colorectal cancer (CRC). Using a murine model of inflammation-induced colon tumorigenesis, we determined how genetic mutations alter colon tumor cell differentiation. Inflammation induced by enterotoxigenic Bacteroides fragilis (ETBF) colonization of multiple intestinal neoplasia (MinApcΔ716/+) mice triggers loss of heterozygosity of Apc causing colon tumor formation. Here, we report that the addition of BRAFV600E mutation (BRAFF-V600ELgr5tm1(Cre/ERT2)CleMinApcΔ716/+, BLM) or knocking out Msh2 (Msh2LoxP/LoxPVil1-creMinApcΔ716/+, MSH2KO) in the Min model altered colon tumor differentiation. Using single-cell RNA sequencing, we uncovered the differences between BLM, Min, and MSH2KO tumors at a single-cell resolution. BLM tumors showed an increase in differentiated tumor epithelial cell lineages and a reduction in the tumor stem cell population. Interestingly, the tumor stem cell population of BLM tumors had revival colon stem cell characteristics with low WNT signaling and an increase in RevCSC marker gene expression. In contrast, MSH2KO tumors were characterized by an increased tumor stem cell population that had higher WNT signaling activity compared to Min tumors. Furthermore, overall BLM tumors had higher expression of transcription factors that drive differentiation, such as Cdx2, than Min tumors. Using RNA velocity, we identified additional potential regulators of BLM tumor differentiation such as NDRG1. The role of CDX2 and NDRG1 as putative regulators for BLM tumor cell differentiation was verified using organoids derived from BLM tumors. Our results demonstrate the critical connections between genetic mutations and cell differentiation in inflammation-induced colon tumorigenesis. Understanding such roles will deepen our understanding of inflammation-associated colon cancer.

Abstract 4243: Dietary flavonoids prevent colon tumor formation in ApcMin/+ mice in a microbiome- and sex-dependent manner

Abstract Background: A diet rich in colorful fruits and vegetables is effective for the prevention of various inflammation-induced cancer types. Mechanistically, this effect has been attributed to the potent antioxidant properties of flavonoid molecules. However, contrary to observations in mice, the success of flavonoids in human dietary cancer prevention trials is often dampened due to large interpersonal variation. Antioxidant activity alone does not explain this variability, suggesting there is an additional important variable that has not been accounted for. Since flavonoids have a poor bioavailability and predominantly passage into the large intestine, we hypothesize that gut microbial metabolism is essential for flavonoid bioactivity in colon cancer prevention. Goals and Objectives: The goal of this study was to evaluate the impact of microbiota composition on the efficacy of dietary flavonoids in preventing intestinal tumorigenesis. Methods: We used the adenomatous polyposis coli - multiple intestinal neoplasia (ApcMin/+) mouse model, which is genetically predisposed to develop adenomas along its gastrointestinal tract. Development of these adenomas and eventual adenocarcinoma formation is further influenced by factors such as inflammation, dietary input and the gut microbiota. Animals were fed a control high fat diet (HFD) or prevention diets consisting of 1% berry extract, 1% purified flavonoid or 1% microbial catabolite, all on the HFD background. The contribution of the microbiota was modelled by including experimental groups that received an antibiotic cocktail in their drinking water throughout the course of the experiment. For these animals, microbiota community composition was determined by 16S rRNA sequencing, plasma was collected for histological profiling and metabolomics analysis and end-point measurements of intestinal tumor numbers and size were performed. Results: Supplementation with berry extract significantly reduced colon tumor numbers and incidence in male, but not in female mice. This effect was negated in mice on antibiotic drinking water, implicating the involvement of the gut microbiota. Community analysis revealed a relative increase in Erysipelotrichaceae, Clostridia and Akkermansia in the berry supplemented versus HFD control mice. In addition, their systemic monocyte counts were reduced. Dietary supplementation with a major gut microbial flavonoid catabolite, did not reduce colon tumor formation, suggesting the functional involvement of different microbial metabolites. Conclusions: Our study demonstrates the involvement of the mouse gut microbiota in dietary prevention of colon tumor formation. These effects impact circulating monocytes and are linked to changes in the plasma metabolome. We are currently elucidating the microbial actors and associated molecular pathways involved. Citation Format: Beckey DeLucia, Jan Claesen. Dietary flavonoids prevent colon tumor formation in ApcMin/+ mice in a microbiome- and sex-dependent manner. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4243.

Dietary inclusion of nitrite-containing frankfurter exacerbates colorectal cancer pathology and alters metabolism in APCmin mice

Colorectal cancer (CRC) is the second most prevelant malignancy in Europe and diet is an important modifiable risk factor. Processed meat consumption, including meats with preservative salts such as sodium nitrite, have been implicated in CRC pathogenesis. This study investigated how the CRC pathology and metabolic status of adenomatous polyposis coli (APC) multiple intestinal neoplasia (min) mice was perturbed following 8 weeks of pork meat consumption. Dietary inclusions (15%) of either nitrite-free pork, nitrite-free sausage, or nitrite-containing sausage (frankfurter) were compared against a parallel control group (100% chow). Comprehensive studies investigated: gastrointestinal tract histology (tumours), aberrant crypt foci (ACF), mucin deplin foci (MDF), lipid peroxidation (urine and serum), faecal microbiota, and serum metabolomics (599 metabolites). After 8 weeks mice consuming the frankfurter diet had 53% more (P = 0.014) gastrointestinal tumours than control, although ACF and MDF did not differ. Urine and serum lipid peroxidation markers were 59% (P = 0.001) and 108% (P = 0.001) higher, respectively in the frankfurter group. Gut dysbiosis was evident in these mice with comparably fewer Bacteriodes and more Firmicutes. Fasting serum levels of trimethylamine N-oxide (TMAO) and numerous triglycerides were elevated. Various serum phosphotidylcholine species were decreased. These results demonstrate that nitrite-containing sausages may exaccerbate the development of CRC pathology in APCMin mice to a greater extent than nitrite-free sausages, and this is associated with greater lipid peroxidation, wide-ranging metabolic alternation and gut dysbiosis.

Chemopreventive effect of 4'-hydroxychalcone on intestinal tumorigenesis in ApcMin mice.

Chalcones and its derivatives are reported to exhibit anti-cancer effects in several cancer cell lines, including colon cancer cells. However, the in vivo anticancer effects and associated mechanisms of chalcones against intestinal tumorigenesis currently remain unclear. The aim of the present study was to investigate the chemopreventive effect of a chalcone derivative, 4′-hydroxychalcone (4-HC), in a transgenic adenomatous polyposis coli multiple intestinal neoplasia mouse model (ApcMin) of spontaneous intestinal adenomas. ApcMin mice were fed 4-HC (10 mg/kg/day) or the vehicle control by oral gavage starting at 8 weeks of age, and were sacrificed at 20 weeks. The administration of 4-HC significantly decreased the number of colon adenomas by 45% and the size of colon adenomas by 35% compared with the respective controls. Similarly, the number of adenomas in the distal small intestine (DSI) and proximal small intestine also decreased by 35 and 33%, respectively, in 4-HC-treated mice, and adenoma size in the DSI decreased by 39% compared with the respective controls. Treatment with 4-HC strongly decreased proliferation in colon and DSI adenomas, as detected by immunofluorescence staining with the proliferation marker protein Ki-67, and promoted apoptosis in colon adenomas, as detected by TUNEL immunofluorescence staining. In addition, decreased mRNA expression of β-catenin target genes, including c-Myc, Axin2 and CD44, in colon adenomas of 4-HC-treated animals demonstrated the involvement of the Wnt/β-catenin signaling pathway in the initiation and progression of colon neoplasms. Treatment with 4-HC also decreased the protein levels of β-catenin in colon adenomas, as demonstrated by immunofluorescence staining. The results suggested that 4-HC may be a promising candidate for the chemoprevention of intestinal tumorigenesis, and further investigations are required to evaluate its clinical utility.

Intraepithelial Lymphocytes Suppress Intestinal Tumor Growth by Cell-to-Cell Contact via CD103/E-Cadherin Signal.

Background & AimsThe reason why small intestinal cancer is rarer than colorectal cancer is not clear. We hypothesized that intraepithelial lymphocytes (IELs), which are enriched in the small intestine, are the closest immune cells to epithelial cells, exclude tumor cells via cell-to-cell contact.MethodsWe developed DPE-green fluorescent protein (DPE-GFP) × adenomatous polyposis coli; multiple intestinal neoplasia (APCmin ) mice, which is a T-cell–reporter mouse with spontaneous intestinal tumors. We visualized the dynamics of IELs in the intestinal tumor microenvironment and the interaction between IELs and epithelial cells, and the roles of cell-to-cell contact in anti-intestinal tumor immunity using a novel in vivo live-imaging system and a novel in vitro co-culture system.ResultsIn the small intestinal tumor microenvironment, T-cell movement was restricted around blood vessels and the frequency of interaction between IELs and epithelial cells was reduced. Genetic deletion of CD103 decreased the frequency of interaction between IELs and epithelial cells, and increased the number of small intestinal tumors. In the co-culture system, wild-type IELs expanded and infiltrated to intestinal tumor organoids from APCmin mice and reduced the viability of them, which was cell-to-cell contact and CD103 dependent.ConclusionsThe abundance of IELs in the small intestine may contribute to a low number of tumors, although this system may not work in the colon because of the sparseness of IELs. Strategies to increase the number of IELs in the colon or enhance cell-to-cell contact between IELs and epithelial cells may be effective for the prevention of intestinal tumors in patients with a high cancer risk.

Tensin4 (TNS4) is upregulated by Wnt signalling in adenomas in multiple intestinal neoplasia (Min) mice

Summary Apc Min/+ mice are regarded as a standard animal model of colorectal cancer (CRC). Tensin4 (TNS4 or Cten) is a putative oncogene conferring features of stemness and promoting motility. Our objective was to assess TNS4 expression in intestinal adenomas and determine whether TNS4 is upregulated by Wnt signalling. ApcMin/+ mice (n = 11) were sacrificed at approximately 120 days old at the onset of anaemia signs. Small intestines were harvested, and Swiss roll preparations were tested for TNS4 expression by immunohistochemistry (IHC). Individual polyps were also separately collected (n = 14) and tested for TNS4 mRNA expression and Kras mutation. The relationship between Wnt signalling and TNS4 expression was tested by Western blotting in the human CRC cell line HCT116 after inhibition of β‐catenin activity with MSAB or its increase by transfection with a Flag β‐catenin expression vector. Overall, 135/148 (91.2%) of the total intestinal polyps were positive for TNS4 expression by IHC, whilst adjacent normal areas were negative. RT‐qPCR analysis showed approximately 5‐fold upregulation of TNS4 mRNA in the polyps compared to adjacent normal tissue and no Kras mutations were detected. In HCT116, β‐catenin inhibition resulted in reduced TNS4 expression, and conversely, β‐catenin overexpression resulted in increased TNS4 expression. In conclusion, this is the first report linking aberrant Wnt signalling to upregulation of TNS4 both during initiation of intestinal adenomas in mice and in in vitro models. The exact contribution of TNS4 to adenoma development remains to be investigated, but the Apc Min/+ mouse represents a good model to study this.

Epigenetic Changes Induced by Bacteroides fragilis Toxin.

Enterotoxigenic Bacteroides fragilis (ETBF) is a Gram-negative, obligate anaerobe member of the gut microbial community in up to 40% of healthy individuals. This bacterium is found more frequently in people with colorectal cancer (CRC) and causes tumor formation in the distal colon of multiple intestinal neoplasia (Apcmin/+ ) mice; tumor formation is dependent on ETBF-secreted Bacteroides fragilis toxin (BFT). Because of the extensive data connecting alterations in the epigenome with tumor formation, initial experiments attempting to connect BFT-induced tumor formation with methylation in colon epithelial cells (CECs) have been performed, but the effect of BFT on other epigenetic processes, such as chromatin structure, remains unexplored. Here, the changes in gene expression (transcriptome sequencing [RNA-seq]) and chromatin accessibility (assay for transposase-accessible chromatin using sequencing) induced by treatment of HT29/C1 cells with BFT for 24 and 48 h were examined. Our data show that several genes are differentially expressed after BFT treatment and that these changes relate to the interaction between bacteria and CECs. Further, sites of increased chromatin accessibility are associated with the location of enhancers in CECs and the binding sites of transcription factors in the AP-1/ATF family; they are also enriched for common differentially methylated regions (DMRs) in CRC. These data provide insight into the mechanisms by which BFT induces tumor formation and lay the groundwork for future in vivo studies to explore the impact of BFT on nuclear structure and function.

A novel mouse model of sporadic colon cancer induced by combination of conditional Apc genes and chemical carcinogen in the absence of Cre recombinase.

Although valuable insights into colon cancer biology have been garnered from human colon cancer cell lines and primary colonic tissues, and animal studies using human colon cancer xenografts, immunocompetent mouse models of spontaneous or chemically induced colon cancer better phenocopy human disease. As most sporadic human colon tumors present adenomatous polyposis coli (APC) gene mutations, considerable effort has gone into developing mice that express mutant Apc alleles that mimic human colon cancer pathogenesis. A serious limitation of many of these Apc-mutant murine models, however, is that these mice develop numerous tumors in the small intestine but few, if any, in the colon. In this work, we examined three spontaneous mouse models of colon tumorigenesis based upon the widely used multiple intestinal neoplasia (Min) mouse: mice with either constitutive or conditional Apc mutations alone or in combination with caudal-related homeobox transcription factor CDX2P-Cre transgene - either with or without exposure to the potent colon carcinogen azoxymethane. Using the CDX2 promoter to drive Cre recombinase transgene expression effectively inactivated Apc in colonocytes, creating a model with earlier tumor onset and increased tumor incidence/burden, but without the Min mouse model's small intestine tumorigenesis and susceptibility to intestinal perforation/ulceration/hemorrhage. Most significantly, azoxymethane-treated mice with conditional Apc expression, but absent the Cre recombinase gene, demonstrated nearly 50% tumor incidence with two or more large colon tumors per mouse of human-like histology, but no small intestine tumors - unlike the azoxymethane-resistant C57BL/6J-background Min mouse model. As such this model provides a robust platform for chemoprevention studies.

Non-toxigenic Bacteroides fragilis (NTBF) administration reduces bacteria-driven chronic colitis and tumor development independent of polysaccharide A.

Polysaccharide A (PSA), an immunogenic capsular component of non-toxigenic Bacteroides fragilis (NTBF) strain NCTC 9343, is reported to promote mucosal immune development and suppress colitis. Contrastingly, enterotoxigenic Bacteroides fragilis (ETBF) is highly associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC), rapidly inducing IL-17-dependent murine colitis and tumorigenesis. In specific-pathogen-free (SPF) C57BL/6 wild type (WT) and multiple intestinal neoplasia (MinApc716+/−) mice, we show that sequential treatment of the NTBF strain, 9343, followed by the ETBF strain, 86–5443-2–2 (86), diminished colitis and tumorigenesis. Mice treated simultaneously with 9343 and 86 exhibited both severe colitis and tumorigenesis. Abrogated disease severity in sequentially treated mice was attributed to 9343 strain dominance and decreased IL-17A, but 86 colonization prior to or simultaneous with 9343 mitigated the anti-inflammatory effect of 9343. Remarkably, 9343-mediated protection was independent of PSA, as sequentially treated mice receiving ΔPSA 9343 exhibited similar protection. Further, SPF WT and Min mice colonized with PSA-competent or PSA-deficient 9343 exhibited similar IL-10, IL-17, and IFN-γ responses. Treatment of 86-colonized mice with 9343 failed to disrupt 86 pathogenesis. Our findings demonstrate 9343 colonization, independent of PSA, offers prophylaxis against colitis-inducing 86 but may not be a valid therapy once colitis is established.

CXCR4 inhibitor, MSX‐122 suppresses AOM‐induced colon cancer in Apc+/Min mouse

IntroductionIn prior studies, we showed that EGFR is required for tumor promotion by Western diet in the azoxymethane (AOM) model of sporadic colon cancer and the AOM/DSS model of inflammation‐associated colon cancer. We also demonstrated that ADAM17, the metalloprotease responsible for shedding membrane‐bound EGFR ligands, controls tumor development in both the AOM and the Apc+/mutant multiple intestinal neoplasia (Min) mouse model. Furthermore, we established that Sdf1a‐CXCR4 signals activated EGFR by an ADAM17‐dependent mechanism in colon cancer cells; and that Western diet up‐regulated Sdf1a‐CXCR4 and ADAM17 in colonic mucosa. We hypothesized that CXCR4 blockade might inhibit colon cancer development. The aim of this study was to test the ability of a novel CXCR4 antagonist, MSX‐122 (substituted benzylamine) to inhibit AOM‐promoted colon cancer in Apc+/Min mice. Min mice without AOM treatment mostly develop small intestinal tumors, whereas AOM‐treated Apc+/Min mice develop colon cancers (Suzui et al 2002).MethodsIn studies in cell culture, we examined the ability of MSX‐122 to block Sdf1a‐induced EGFR transactivation. In vivo, Apc+/Min mice were given AOM (10 mg i.p./kg body weight) and two weeks later mice were started on a Western diet (20% fat). Mice received MSX‐122 i.p. (2.5 mg/kg body weight, n=12) or vehicle (DMSO, n=13) three times weekly and were killed after 10 wks.ResultsMSX‐122 blocked EGFR transactivation by Sdf1a in HT29 colon cancer cells as assessed by reductions in pErbB2, pAKT and pERK. In vivo, MSX‐122 was well tolerated with mice showing comparable weight gain to vehicle‐treated mice. As expected, AOM induced colon tumors in Apc+/Min mice. MSX‐122 significantly reduced colon tumor incidence (92.3% vs. 50.0%, p=0.025) and cancer incidence (69.2% vs. 16.7%, p=0.015). MSX‐122 also reduced tumor burden as assessed by total tumor multiplicity (1.8 vs. 1.0 tumor per TBM; p=0.02), tumor volume (169.5 mm3 vs. 61.2 mm3, p<0.023) and tumor proliferation as assessed by Ki67 staining (37.2±3.6% vs. 25.3±5.8%, p<0.005). Cancer multiplicity also appeared to be decreased (1.6 vs. 1.0 tumor/TBM, p=0.17).ConclusionsMSX‐122 blocked EGFR transactivation by CXCR4 agonist Sdf1a in colon cancer cells. MSX‐122 also inhibited colon tumor development and progression in the AOM‐promoted Apc+/Min mouse model. We speculate that MSX‐122, which was well tolerated in a phase 1b clinical trial (Painter, W. 2015), could serve as a chemopreventive agent in individuals at increased risk for colon cancer.Support or Funding InformationNIH R01CA164124This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Modified Shenlingbaizhu decoction reduces intestinal adenoma formation in adenomatous polyposis coli multiple intestinal neoplasia mice by suppression of hypoxia-inducible factor 1α-induced CD4 + CD25+ forkhead box P3 regulatory T cells

OBJECTIVETo test the hypothesis that modified Shenlingbaizhu decoction (MSD) attenuates the formation of intestinal adenomas by regulating activation of CD4+CD25+ forkhead box P3 (FoxP3) regulatory T cells (Tregs) by downregulation of hypoxia-inducible factor 1α (HIF-1α). METHODSChemical fingerprints of ginsenoside Rb1, ginsenoside Rc, paeoniflorin, and dioscin in standard extractions were used as material bases of MSD. Adenomatous polyposis coli multiple intestinal neoplasia (ApcMin/+) mice, which harbor a mutation in adenomatous polyposis coli, were used to host intestinal adenomas. Peripheral blood and spleen Tregs were analyzed by flow cytometry. Protein expression was analyzed by immunohistochemistry and Western blotting. RESULTSThe number and size of intestinal adenomas were significantly reduced by MSD treatment. Mucosal thickening and the spleen size were also substantially decreased by MSD. The carcinogenesis process in ApcMin/+ mice resembled that of human colorectal cancer. Molecular markers of neoplasms, such as β-catenin, cyclooxygenase-2, proliferating cell nuclear antigen, and p53, were substantially ameliorated by MSD treatment. Moreover, MSD downregulated peripheral and spleen CD4 + CD25+FoxP3+Tregs and reduced in situ expression of CD4, CD25, and FoxP3 in intestinal adenomas. MSD also suppressed HIF-1α expression in the intestinal adenomas, and HIF-1α inhibition decreased expression of FoxP3 in Jurkat T cells under hypoxic conditions. CONCLUSIONMSD is a valid prescription to control the formation of intestinal adenomas in ApcMin/+ mice. It exerts anti-cancer effects partially through suppression of HIF-1α that induced activation of CD4+CD25+FoxP3+ Tregs in vivo and in vitro.

Abstract 2401: Connecting oxidative DNA damage to epigenetic alterations during inflammation-driven tumorigenesis

Abstract Inflammation contributes to the development of a diverse array of diseases, including cancer. At sites of chronic inflammation epithelial cells are exposed to high levels of reactive oxygen species and undergo cancer-associated DNA methylation changes, suggesting that inflammation initiates epigenetic alterations. Cancer cells are globally DNA hypomethylated, but have aberrant gains in promoter DNA methylation that transcriptionally silence tumor suppressor genes (TSGs), linking DNA methylation directly to tumorigenesis. However, the mechanisms of targeting and initiation for these stable disease-specific epigenetic marks are unknown. We have linked inflammation and oxidative DNA damage to acute changes in the interaction of epigenetic silencing proteins with each other and the chromatin. Recently, we demonstrated that the mismatch repair (MMR) protein heterodimer MSH2-MSH6 participates in the oxidative damage-induced recruitment of DNA methyltransferase 1 (DNMT1) to chromatin and provided evidence that the role of DNMT1 at sites of oxidative damage is to reduce transcription. To connect these findings to epigenetic changes in tumors we use a model of inflammation-driven tumorigenesis where we infect mice with the human commensal bacterium enterotoxigenic Bacteriodes fragilis (ETBF). ETBF infection causes colon inflammation that drives tumorigenesis in Multiple intestinal neoplasia (Min) mice. The central hypothesis for this work is that oxidative damage at sites of inflammation causes acute genome-wide changes in the binding of epigenetic silencing proteins that result in the permanent epigenetic silencing of genes in tumors that form at the sites of exposure. Using genome-wide DNA methylation techniques we identified TSGs with increased promoter DNA methylation and decreased expression in tumors from ETBF infected Min mice as compared to normal tissue. In Min mice lacking expression of Msh2 in their intestinal epithelium (Msh2lox/loxVCMin) there is a loss of the inflammation-induced change in binding of epigenetic proteins that occurs in Min mice even though the cytokine response to infection is normal. Because they lack functional MMR, ETBF infection of Msh2lox/loxVCMin mice causes an increase in colon tumor number and these tumors are positive for microsatellite instability, unlike tumors from ETBF infected Min mice. Importantly, DNA hypo- and hypermethylation changes in tumors from Msh2lox/loxVCMin ETBF infected mice are reduced both globally and at promoter CpG islands of candidate TSGs as compared to tumors from Min ETBF infected mice. Altogether, this work suggests a novel mechanism by which oxidative damage induces acute epigenetic changes through the interaction of DNMT1 with MMR proteins and that this acute change drives DNA methylation alterations during tumorigenesis. Citation Format: Ashley Maiuri, Ning Ding, Heather M. O'Hagan. Connecting oxidative DNA damage to epigenetic alterations during inflammation-driven tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2401. doi:10.1158/1538-7445.AM2017-2401

Chemoprevention of intestinal tumorigenesis by the natural dietary flavonoid myricetin in APCMin/+ mice.

Myricetin is a natural dietary flavonoid compound. We evaluated the efficacy of myricetin against intestinal tumorigenesis in adenomatous polyposis coli multiple intestinal neoplasia (APCMin/+) mice. Myricetin was given orally once a day for 12 consecutive weeks. APCMin/+ mice fed with myricetin developed fewer and smaller polyps without any adverse effects. Histopathological analysis showed a decreased number of dysplastic cells and degree of dysplasia in each polyp. Immunohistochemical and western blot analysis revealed that myricetin selectively inhibits cell proliferation and induces apoptosis in adenomatous polyps. The effects of myricetin were associated with a modulation the GSK-3β and Wnt/β-catenin pathways. ELISA analysis showed a reduced concentration of pro-inflammatory cytokines IL-6 and PGE2 in blood, which were elevated in APCMin/+ mice. The effect of myricetin treatment was more prominent in the adenomatous polyps originating in the colon. Further studies showed that myricetin downregulates the phosphorylated p38 MAPK/Akt/mTOR signaling pathways, which may be the mechanisms for the inhibition of adenomatous polyps by myricetin. Taken together, our data show that myricetin inhibits intestinal tumorigenesis through a collection of biological activities. Given these results, we suggest that myricetin could be used preventatively to reduce the risk of developing colon cancers.

Abstract 5248: ED-71, an analogue of Vitamin D3, blocks the promotion but not the initiation of colorectal tumors in the Apc+/Min-FCCC mouse model

Abstract Results from several studies demonstrate an inverse relationship between circulating levels of Vitamin D and risk of colorectal cancer. Eldecalcitol (1α,25-dihydroxy-2β-(3-hydroxypropyloxy) Vitamin D3; ED-71) is a novel analog of calcitriol, the most active form of Vitamin D3. ED-71 is more potent in stimulating bone remodeling and has been approved in Japan for the treatment of osteoporosis. The goal of this study was to assess the ability of ED-71 to inhibit spontaneous colorectal adenomas in a unique strain of multiple intestinal neoplasia (Apc+/Min-FCCC) mice. Male mice (6 wks of age) were randomized to treatment groups based on colon tumor status (endoscopic confirmation as tumor-free or -bearing) and body weight (bw) and administered: vehicle (MCT), calcitriol (0.25 μg/kg bw), or ED-71 (0.05 or 0.1 μg/kg bw) by gavage. Mice were treated every other day and bws were recorded weekly. After 14 wks of treatment, the small intestines and colons were excised and examined for gross tumors. Colorectal tumors >3 mm in diameter were frozen for gene expression analyses. The remaining tissue was fixed in formalin and processed for histological review. The multiplicity of gross small intestinal tumors in animals treated with ED-71 (both doses) was comparable to that of vehicle-treated controls. In contrast, the multiplicity of small intestinal tumors was elevated 34.6% over that of controls in animals treated with calcitriol (Mean ± SEM: 28.4 ± 2.6 vs. 21.1 ± 2.8, respectively; P = 0.034). The ability of ED-71 to inhibit colon tumorigenesis was evaluated independently in mice with vs. without tumors at treatment initiation. In tumor-bearing mice, neither calcitriol nor ED-71 (both doses) had any significant effect on the multiplicity of colorectal tumors as compared to control mice. However in tumor-free mice, ED-71 (0.1 μg/kg bw) reduced the mean incidence of adenomas (> 4 crypts) by 47% (ED-71 - 45.5%, controls 92.3%; P = 0.02) and the multiplicity by 47.6% (Mean ± SEM: ED-71 - 1.1 ± 0.39, controls - 2.1 ± 0.72; P > 0.05). In contrast, the multiplicity of microadenomas (≤ 4 crypts) was increased in mice treated with ED-71 (0.1 μg/kg bw) as compared to controls (0.9 ± 0.22 vs. 0.5 ± 0.25 P = 0.06, respectively). These findings suggest that ED-71 is effective in preventing the transition of microadenomas to mature adenomas. The lack of an effect of ED-71 on colon tumor development in mice bearing tumors at baseline could be due in part to loss of the Vitamin D receptor in colon adenomas, as confirmed by real-time PCR. Insight into the mechanism by which ED-71 inhibits adenoma development is being gained from analyses of Vitamin D signaling and microRNA expression in treated colonic epithelial cells. These promising data provide support for future studies to determine the potential utility of ED-71 in preventing colorectal cancer in high-risk patients found to be tumor-free during surveillance endoscopy. (Supported by NCI HHSN261201200015I) Citation Format: Wen-Chi L. Chang, Harry S. Cooper, Esther Kaunga, Lisa Vanderveer, Jing Peng, Suen S. Chen, Margie L. Clapper. ED-71, an analogue of Vitamin D3, blocks the promotion but not the initiation of colorectal tumors in the Apc+/Min-FCCC mouse model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5248.

The food processing contaminant glyoxal promotes tumour growth in the multiple intestinal neoplasia (Min) mouse model

Glyoxal is formed endogenously and at a higher rate in the case of hyperglycemia. Glyoxal is also a food processing contaminant and has been shown to be mutagenic and genotoxic in vitro. The tumourigenic potential of glyoxal was investigated using the multiple intestinal neoplasia (Min) mouse model, which spontaneously develops intestinal tumours and is susceptible to intestinal carcinogens.C57BL/6J females were mated with Min males. Four days after mating and throughout gestation and lactation, the pregnant dams were exposed to glyoxal through drinking water (0.0125%, 0.025%, 0.05%, 0.1%) or regular tap water. Female and male offspring were housed separately from PND21 and continued with the same treatment. One group were only exposed to 0.1% glyoxal from postnatal day (PND) 21.There was no difference in the number of intestinal tumours between control and treatment groups. However, exposure to 0.1% glyoxal starting in utero and at PND21 caused a significant increase in tumour size in the small intestine for male and female mice in comparison with respective control groups. This study suggests that glyoxal has tumour growth promoting properties in the small intestine in Min mice.

Fibersol-2 induces apoptosis of Apc-deficient colorectal Cancer (SW480) cells and decreases polyp formation in Apc MIN mice

ABSTRACTThe consumption of dietary fibers has been implicated with a lowered risk of human colorectal cancer. Proposed mechanisms involve alterations in the stool consistency, transit time, and formation of short-chain fatty acid by dietary fiber fermentation, and the reorganization of gut microbiota. Here we show that Fibersol-2, a digest-resistant maltodextrin, not only inhibits proliferation of colorectal SW480 cancer cell lines by increasing reactive oxygen species (ROS), but decreases the numbers of the adenoma count in Multiple Intestinal Neoplasia (MIN) mice carrying a mutation in the Adenomatous Polyposis Coli gene by 84 d of age. These observations provide direct evidence that Fibersol-2 intrinsically contains anti-cancer activity, independent of the intestinal metabolism and any potential interactions with the microbiota.

Reduction of Murine Colon Tumorigenesis Driven by Enterotoxigenic Bacteroides fragilis Using Cefoxitin Treatment.

Chronic inflammation and composition of the colon microbiota have been associated with colorectal cancer in humans. The human commensal enterotoxigenic Bacteroides fragilis (ETBF) is linked to both inflammatory bowel disease and colorectal cancer and, in our murine model, causes interleukin 17A (IL-17A)-dependent colon tumors. In these studies, we hypothesized that persistent colonization by ETBF is required for tumorigenesis. We established a method for clearing ETBF in mice, using the antibiotic cefoxitin. Multiple intestinal neoplasia mice were colonized with ETBF for the experiment duration or were cleared of infection after 5 or 14 days. Gross tumors and/or microadenomas were then evaluated. In parallel, IL-17A expression was evaluated in wild-type littermates. Cefoxitin treatment resulted in complete and durable clearance of ETBF colonization. We observed a stepwise increase in median colon tumor numbers as the duration of ETBF colonization increased before cefoxitin treatment. ETBF eradication also significantly decreased mucosal IL-17A expression. The timing of ETBF clearance profoundly influences colon adenoma formation, defining a period during which the colon is susceptible to IL-17A-dependent tumorigenesis in this murine model. This model system can be used to study the microbiota-dependent and molecular mechanisms contributing to IL-17A-dependent colon tumor initiation.

Procarcinogenic regulatory T cells in microbial-induced colon cancer

ABSTRACTRegulatory T cell (Treg) promote IL-17-mediated colon tumorigenesis in multiple intestinal neoplasia (Min) mice colonized with enterotoxigenic Bacteroides fragilis (ETBF). Although they retain their immunosuppressive function, mucosal Treg are instrumental to initiate ETBF-triggered IL-17 colitis by limiting the availability of IL-2 in the local microenvironment. However, the mechanisms that trigger the recruitment of the pro-carcinogenic Treg in ETBF-colonized colon remained to be elucidated.

Spontaneous initiation, promotion and progression of colorectal cancer in the novel A/J Min/+ mouse.

The C57BL/6J multiple intestinal neoplasia (Min/+) mouse is a widely used murine model for familial adenomatous polyposis, a hereditary form of human colorectal cancer. However, it is a questionable model partly because the vast majority of tumors arise in the small intestine, and partly because the fraction of tumors that progress to invasive carcinomas is minuscule. A/J mice are typically more susceptible to carcinogen-induced colorectal cancer than C57BL/6J mice. To investigate whether the novel Min/+ mouse on the A/J genetic background could be a better model for colorectal cancer, we examined the spontaneous intestinal tumorigenesis in 81 A/J Min/+ mice ranging in age from 4 to 60 weeks. The A/J Min/+ mouse exhibited a dramatic increase in number of colonic lesions when compared to what has been reported for the conventional Min/+ mouse; however, an increase in small intestinal lesions did not occur. In addition, this novel mouse model displayed a continual development of colonic lesions highlighted by the transition from early lesions (flat ACF) to tumors over time. In mice older than 40 weeks, 13 colonic (95% CI: 8.7-16.3) and 21 small intestinal (95% CI: 18.6-24.3) tumors were recorded. Notably, a considerable proportion of those lesions progressed to carcinomas in both the colon (21%) and small intestine (51%). These findings more closely reflect aspects of human colorectal carcinogenesis. In conclusion, the novel A/J Min/+ mouse may be a relevant model for initiation, promotion and progression of colorectal cancer.

Regulatory T-cell Response to Enterotoxigenic Bacteroides fragilis Colonization Triggers IL17-Dependent Colon Carcinogenesis.

Many epithelial cancers are associated with chronic inflammation. However, the features of inflammation that are procarcinogenic are not fully understood. Regulatory T cells (Treg) typically restrain overt inflammatory responses and maintain intestinal immune homeostasis. Their immune-suppressive activity can inhibit inflammation-associated cancers. Paradoxically, we show that colonic Tregs initiate IL17-mediated carcinogenesis in multiple intestinal neoplasia mice colonized with the human symbiote enterotoxigenic Bacteroides fragilis (ETBF). Depletion of Tregs in ETBF-colonized C57BL/6 FOXP3(DTR) mice enhanced colitis but diminished tumorigenesis associated with shifting of mucosal cytokine profile from IL17 to IFNγ; inhibition of ETBF-induced colon tumorigenesis was dependent on reduced IL17 inflammation and was independent of IFNγ. Treg enhancement of IL17 production is cell-extrinsic. IL2 blockade restored Th17 responses and tumor formation in Treg-depleted animals. Our findings demonstrate that Tregs limit the availability of IL2 in the local microenvironment, allowing the Th17 development necessary to promote ETBF-triggered neoplasia, and thus unveil a new mechanism whereby Treg responses to intestinal bacterial infection can promote tumorigenesis. Tregs promote an oncogenic immune response to a common human symbiote associated with inflammatory bowel disease and colorectal cancer. Our data define mechanisms by which mucosal Tregs, despite suppressing excessive inflammation, promote the earliest stages of immune procarcinogenesis via enhancement of IL17 production at the expense of IFNγ production.