Multiple Intestinal Neoplasia Research Articles

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

Genetically and dietary induced obesity associate differently with gut microbiota in a murine intestinal tumorigenesis model

Background: Overweight and obesity are risk factors for human colorectal cancer. Growing evidence suggests that the gut microbiome affects both obesity and cancer. In this study, we examined how the murine microbiota composition correlated with obesity, intestinal tumorigenesis, glucose regulation, and inflammation. Materials and Methods: We used 16S ribosomal RNA gene analyses of feces and data obtained from a double-mutant mouse model; multiple intestinal neoplasia (Min), mice, which spontaneously develop intestinal tumors, crossed with obesity (ob), mice, which develop obesity, fed 10% or 45% fat diet. Results: We found that diet and genotypes imposed a major impact on the gut microbiota composition. Likewise, we found strong associations of the microbiota composition with obesity, number of small intestinal tumors, and blood glucose levels. Specifically, bacteria related to Clostridium perfringens and Lactobacillus showed strong positive associations with both dietary induced and genetically induced obesity, while Bacteroidales showed strong negative associations. Representatives of Lachnospiraceae and Peptostreptococcaceae only showed significant negative associations with genetically induced obesity and no associations with dietary induced obesity. Conclusions: We found complex associations between the microbiota and genetic background, diet, obesity, glucose levels, inflammation, and intestinal tumorigenesis. This could contribute to the lack of consensus between the results in previous studies regarding correlations of microbiota with obesity and cancer.

Abstract B137: Establishment of a variety of primary mouse tumor allografts of defined disease pathways for evaluating immunotherapy

Abstract Lack of relevant animal model is a major bottleneck for developing novel immunotherapy. The current workhorse is syngeneic mouse tumor model where mouse cancer cell lines were engrafted in syngeneic mice. However, these models suffer from several limitations: 1) only a few available and responsive to the current checkpoint inhibitors – for given strains of mouse, few choices of cells/disease types; 2) not mimicking patient tumors since it is in vitro immortalized cell lines1; 3) not reflective of patient disease pathways thus unfit for common target agents, either in mono- or combination therapy. We have attempted to establish allografts of spontaneous mouse tumors derived from GEMMs (MuPrime®) as a new type of immuno-oncology models2 with following advantages: 1) its primary nature of “stem cell diseases” and relevant tumor microenvironment as seen in patient derived xenografts (PDX) or patients1; 2) its diverse cancer types/strains of mice; 3) engineered oncogenic drivers as seen in human diseases, e.g. heterozygous APCmin/wt3,4,5, deriving from a wide range of available GEMMs, suitable for targeted agents. Thus far, we have continued to build a small library of allografts and are testing them to facilitate pharmacological investigation, particularly those of immuno-oncology. Kras G12D mutation and p53 loss-of-function are most common genetic abnormality found in a variety of cancers, e.g. lung, pancreas, colon, lymphoma, etc. We generated a conditional compound mutant GEMM. By introducing adeno-Cre to different organ sites of this GEMM, we created a series of mouse tumors, including lung, pancreas, colon, and lymphoma, with genetic lesions of KrasG12D/+/P53(-/-). We have further allografted subcutaneous these tumors into syngeneic parental mous strain. These allograft tumors, while carrying same mutations, display distinct histopathology: pancreatic tumor exhibits the features commonly found in human PDAC (e.g. glandular tumor structures and exuberant stroma); lung cancer features NSCLC-adenocarcinoma. They also demonstrated different tumor immune microenvironment. This set of allografts of different diseases but of the same oncogenic driver could be particularly ideal to investigate their sensitivities to immunotherapies, as well as to combination therapies targeting MAPK pathway and immune modulation. At present, we are genomically, immunologically and pharmacologically profiling these models. The data of these studies will be presented at the meeting.

Changes in intestinal immunity, gut microbiota, and expression of energy metabolism–related genes explain adenoma growth in bilberry and cloudberry-fed ApcMin mice

We showed previously that ellagitannin-rich cloudberries and anthocyanin-rich bilberries reduce the number of intestinal adenomas in multiple intestinal neoplasia/+ (ApcMin) mice. We also found that cloudberries decreased the size of adenomas, whereas bilberries increased it. Here we hypothesized that the difference in adenoma growth could be explained by dissimilar effects of the berries on intestinal immune responses and gut microbiota, potentially driven by the distinct polyphenol compositions of the 2 berries. Our objectives were to investigate lymphocyte subtypes and the predominant cecal bacterial diversity in mice fed with bilberries and cloudberries, and to analyze global gene expression profiles in the intestinal mucosa. Immunostainings of CD3+ T lymphocytes, FoxP3+ regulatory T lymphocytes, and CD45R+ B lymphocytes revealed a smaller ratio of intraepithelial to all mucosal CD3+ T lymphocytes in the cloudberry-fed mice compared with controls, suggesting an attenuation of inflammation. Bilberry feeding induced no changes in the density of any of the lymphocyte subtypes. The predominant bacterial diversity in cecal contents, analyzed using polymerase chain reaction–denaturating gradient gel electrophoresis, was higher in the bilberry group than in the control or cloudberry groups. The microbial profiles of cloudberry-fed mice clustered together and were associated with small adenoma size. Pathway analyses of gene expression data showed that cloudberry down-regulated and bilberry up-regulated the expression of energy metabolism–related genes in the intestinal mucosa. In conclusion, attenuation of intestinal inflammation, changes in microbial profiles, and down-regulation of mucosal energy metabolism may account for the smaller adenoma size in cloudberry-fed mice in comparison to bilberry-fed mice.

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.

Procarcinogenic regulatory T cells in microbial-induced colon cancer

ABSTRACT Regulatory 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.

Corrigendum to “Genetic and Diet-Induced Obesity Increased Intestinal Tumorigenesis in the Double Mutant Mouse Model Multiple Intestinal Neoplasia X Obese via Disturbed Glucose Regulation and Inflammation”

[This corrects the article DOI: 10.1155/2015/343479.]. In the published paper "Genetic and Diet-Induced Obesity Increased Intestinal Tumorigenesis in the Double Mutant Mouse Model Multiple Intestinal Neoplasia X Obese via Disturbed Glucose Regulation and Inflammation" [1] we mistakenly wrote IL-1β instead of IL-6 in Tables 2 and 3. In addition, IL-6 was not included in the text below the tables stating that it was measured by flow cytometer as was TNFα. The corrected tables are presented here.

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.

Naringin, a natural dietary compound, prevents intestinal tumorigenesis in Apc (Min/+) mouse model.

Naringin is a natural dietary flavonoid compound. We aimed to evaluate the effects of naringin on intestinal tumorigenesis in the adenomatous polyposis coli multiple intestinal neoplasia (Apc (Min/+)) mouse model. Apc (Min/+) mice were given either naringin (150 mg/kg) or vehicle by p.o. gavage daily for 12 consecutive weeks. Mice were killed with ether, and blood samples were collected to assess the concentrations of IL-6 and PGE2. Total intestines were removed, and the number of polyps was examined. Tissue samples of intestinal polyps were subjected to the assays of histopathology, immunohistochemical analysis and Western blotting analysis. Apc (Min/+) mice fed with naringin developed less and smaller polyps in total intestines. Naringin prevented intestinal tumorigenesis without adverse effects. Histopathologic analysis revealed the reduction of dysplastic cells and dysplasia in the adenomatous polyps. The treatments' effects might arise from its anti-proliferation, induction of apoptosis and modulation of GSK-3β and APC/β-catenin signaling pathways. Naringin also exerted its effects on tumorigenesis through anti-chronic inflammation. Naringin prevented intestinal tumorigenesis likely through a collection of activities including anti-proliferation, induction of apoptosis, modulation of GSK-3β and APC/β-catenin pathways and anti-inflammation. Naringin is a potential chemopreventive agent for reducing the risk of colonic cancers.

Abstract B97: Response to checkpoint inhibition by GEMM breast cancer allograft

Abstract Background. Cancer patient's response to immunotherapy, e.g. checkpoint inhibitors, differ greatly, likely due to their genetic composition (e.g. neo-mutation) or immunological profile of tumors. Experimental models may facilitate the identification of responders or of the approach to enhance response. Syngeneic mouse tumor models have been widely used as experimental model for testing surrogate immunotherapy, but limited by the fact that only a few are available and respond to the current checkpoint inhibitors. Allografts of mouse spontaneous tumors (MuPrimeTM) may be used as new type of I/O model with advantages: 1) its primary natures with “stem cell diseases” and relevant tumor microenvironment as seen in PDX1-5; 2) diverse cancer types and deriving from wider range of available spontaneous mouse tumors. Method. We created a MuPrime, MBR6004, by allografting the breast adenocarcinoma derived from GEMM-MMTV-PyVT in FVB/N mice1. We then characterized the model by examine it subcutaneous and orthotopic growth, and its ability to metastasis. We also transcriptome-sequenced and immune-profiled the tumor, and assessed its response to different treatments, including I/O therapy. Results. MBR6004 was found to over-express HER2 but negative for ER and PR. It maintains original primary tumour histopathology, grows robustly, and is confirmed to express its original transgene. It is also resistant to docetaxel. The orthotopic implantation resulted in lung metastasis. We can detected and quantitatively confirmed tumor-infiltrating immune cells, e.g. TIL, CTL, Treg, immune-suppression macrophage, NK, etc. We confirmed that the tumor cell expressed relatively low PD-L1, but inducible, per flow analysis. Our preliminary data indicated that it partially respond to anti-mouse PD1 and anti-mouse CTLA-4 antibodies when mice are preconditioned. Currently, we are investigating whether the responses are associated with the reduced Treg and increased CD8+ TIL in tumors, and also whether the combination therapy can enhance its tumor response synergistically. Conclusion. Our data seem to suggest that MuPrime could be another type of I/O model alternative to commonly used syngeneic cell line derived models at present.

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.

Abstract B42: Modeling MDS in mice through precise molecular lesions in APC and mDia1.

Abstract While the murine equivalent to “5q– syndrome” should map to the distal arms of murine chromosomes 11 and 18, molecular attempts have been unsuccessful in generating a reliable mouse model of myelodysplasia leading to exacerbated myeloid leukemia. Genetic studies suggest interactions between individual proteins in this locus suppress tumor initiation. More specifically, cellular and biochemical studies demonstrated collaboration between two proteins in the commonly deleted regions of 5q– syndrome: mDia1 (mammalian Diaphanous-related Rho GTPase effector formin) and APC (adenomatous polypolis coli). Therefore, we generated mice compounding these two putative disease alleles. Because both mDia1 knockout [Drf1(–/–)] mice and Apcmin (min = multiple intestinal neoplasia; haploinsufficient) mice develop age-dependent myelodysplastic syndrome (MDS), we hypothesized that a mouse strain lacking both proteins will exhibit a more severe MDS phenotype than either mutant allele alone. To define the disease caused by mutation in Drf1 and Apcmin, we monitored erythropoiesis, myelopoiesis, and overall survival. At all ages, mice with both mutant alleles exhibit granulocytosis. Anemia occurs in aged mice (>270 days), exhibiting drastic differences in blood cell morphology that corresponded to differences in long-term survival in comparison to either Drf1–/– or Apcmin animals. Furthermore, immunophenotyping of all subpopulations indicate an accumulation of CD71+/TER-119+ cells in mice with both mutant alleles, however no significant differences in CD11b expression appeared among CD45+ bone marrow subpopulations. Our studies indicate that combined loss of mDia1 and APC expression and function direct disease progression. We are currently defining the hematopoietic precursor cell responsible for anemia and bone marrow failure. This enhanced mouse model also serves as molecular laboratory to study disease progression and to test potential therapeutics under development in our laboratory. Citation Format: Julie Davis Turner, Susan Kitchen-Goosen, Andrew M. Howard, Heather Schumacher, Art S. Alberts. Modeling MDS in mice through precise molecular lesions in APC and mDia1. [abstract]. In: Proceedings of the AACR Special Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(17 Suppl):Abstract nr B42.

Abstract 4194: APC and DIAPH1 collaborate to suppress myelodysplastic syndrome (MDS) pathogenesis

Abstract Myelodysplastic syndromes (MDS) are characterized by complex cytogenetic abnormalities, including loss of all or part of the long arm of chromosome 5 (5q). Known 5q tumor suppressors include APC1 and EGR1. APC is associated with familial colon cancer where it functions to suppress canonical Wnt signaling. Egr1 is a transcription factor that governs expression of tumor suppressor genes ranging from the p53 family to PTEN1. Adjacent to EGR1 is the DIAPH1 gene for the Rho GTPase effector formin DIAPH1. Knockout of Diaph1, Egr, or Apc in mice creates a range of MDS phenotypes. Likewise, mice with the multiple intestinal neoplasia (min/Apcmin) allele develop anemia and MDS most similar to the Diaph1 knockout phenotype. DIAPH1 builds linear actin filaments and stabilizes microtubule dynamics to establish and maintain cell polarity during adhesion, migration, and asymmetric cell division when activated by Rho GTPases, such as RhoB. Combinatorial deficiencies in RhoB (also a known tumor susceptibility gene) with Diaph1 exacerbates the Diaph1 MDS phenotype but not the rate of pathogenesis. RhoB-activated DIAPHs also signal and activate new gene expression by the myocardin-related (MRTF) and Mcm10/Agamous deficiens/ [serum response factor (SRF)] (MADS)-box transcription factors. MRTF-MADS registers changes in actin dynamics downstream of DIAPH1 to activate EGR1 expression through multiple serum response elements (SREs; recognized by SRF) within the EGR1 promoter. DIAPH1 also collaborates with APC in cytoskeletal remodeling as both proteins physically associate with and stabilize microtubules. APC can also nucleate new actin filaments that become processively elongated by DIAPH1. We examined interactions between APC and DIAPH1 signaling to SRF and in suppressing MDS pathogenesis. First, we found that both DIAPH1 and APC activate SRF- regulated gene expression. Consistent with biochemical data showing that DIAPH1 elongates APC-nucleated filaments, activation of SRF by APC relies upon DIAPH1. We bred Apcmin mice to our Diaph1 knockout mice and found that the MDS phenotype is significantly accelerated in Apcmin/Diaph1 knockout mice when compared to either the Apcmin or Diaph1 mutant phenotype. Pathological defects (dysplasia and anemia in peripheral blood and myeloid organs (spleen/bone marrow) requires at least 200 days to develop in either single mutant; combined mutations create aberrant peripheral blood cell pathology by 100 days of age. Consistent with early disease onset, mortality is accelerated in Apcmin /Diaph1-deficient mice. These novel studies show that genetic defects in Diaph1 and Apc synergize to effectively mimic 5q- MDS. Further, the data supports the idea that RhoB - DIAPH1/APC and MRTF-MADS comprise a novel tumor suppression pathway that is essential for hematopoiesis. Apcmin/Diaph1-deficient mice may prove to be a useful pre-clinical model for the development of more effective theranostic tools to attack MDS. Citation Format: Julie D. Turner, Susan M. Kitchen-Goosen, Andrew M. Howard, Heather L. Schumacher, Arthur S. Alberts. APC and DIAPH1 collaborate to suppress myelodysplastic syndrome (MDS) pathogenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4194. doi:10.1158/1538-7445.AM2015-4194

Abstract 2806: Effect of ED-71, an analogue of Vitamin D3, on intestinal neoplasia in the Apc+/Min-FCCC mouse model

Abstract Numerous studies have demonstrated an inverse relationship between circulating Vitamin D levels and risk of colorectal cancer. Although calcitriol, the most active form of Vitamin D3, exhibits promising antitumorigenic activity, its use as a chemopreventive agent has been restricted by its hypercalcemic effect at therapeutic doses. Eldecalcitol (1α,25-dihydroxy-2β-(3-hydroxypropyloxy) Vitamin D3 or ED-71), a novel analog of calcitriol, is more potent than calcitriol in stimulating bone modeling and is approved for the treatment of osteoporosis in Japan. The goal of the present study was to assess the activity of ED-71 against colorectal adenomas in a unique mouse model of spontaneous multiple intestinal neoplasia (Apc+/Min-FCCC mice). In a preliminary dose-finding study, male Apc+/Min-FCCC mice (6 weeks old, 6-7/group) were treated with vehicle (medium chain triglyceride (MCT)), calcitriol (0.25 μg/kg body weight (bw)), or ED-71 (0.2, 0.1, 0.05, 0.025, 0.0125 μg/kg bw) every other day by gavage for 6 weeks. Body weight was recorded weekly and mice were euthanized at the end of the study. ED-71 was well tolerated at all doses tested, with no significant difference in body weight observed in treated animals as compared to controls. Drug toxicity was assessed by measuring serum calcium levels by colorimetric assay (BioVision Inc.) and hepatic alkaline phosphatase (ALP) by ELISA (Antibodies-online.com). No significant effect of ED-71 on serum calcium levels and hepatic ALP activity was observed. However, because some concern exists regarding the ability of mice treated with high-dose ED-71 (0.2 μg/kg bw) to maintain their body weight long-term, ED-71 doses of 0.05 and 0.1 μg/kg bw were selected for the long-term efficacy study. Prior to entry on this study, male Apc+/Min-FCCC mice (6 weeks old) were prescreened endoscopically to determine tumor-bearing status. Mice were randomized based on tumor status (tumor-free or tumor-bearing) and body weight to one of four treatment groups: vehicle (MCT), calcitriol (0.25 μg/kg bw), ED-71 (0.05 μg/kg bw) or ED-71 (0.1 μg/kg bw). Drugs were administered by gavage every other day for 14 weeks. At the end of the study, intestinal tissue was examined grossly and tumor multiplicity was recorded. No significant effect of ED-71 on tumor multiplicity was observed in tumor-bearing mice. However, in tumor-free mice (11-13/group), treatment with ED-71 (0.1 μg/kg bw) reduced the incidence of gross tumors by 36% (P = 0.017) and colon tumor multiplicity by 30% as compared to that of controls (63.6% vs. 100%, 1.4 ± 0.4 vs. 2.0 ± 0.4, respectively). These findings suggest that ED-71 is effective in inhibiting colon tumorigenesis when given to mice prior to tumor formation. These promising data provide support for future studies to determine the potential utility of ED-71 for the prevention of colorectal cancer in high-risk subjects. (Supported by NCI HHSN261201200015I) Citation Format: Wen-Chi L. Chang, Esther Kaunga, Harry S. Cooper, Lisa Vanderveer, Jing Peng, Yongchao Zhang, Chen S. Suen, Margie L. Clapper. Effect of ED-71, an analogue of Vitamin D3, on intestinal neoplasia in the Apc+/Min-FCCC mouse model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2806. doi:10.1158/1538-7445.AM2015-2806

Fecal detection of enterotoxigenic Bacteroides fragilis.

Bacteroides fragilis is a common colonic symbiote of which one subtype, enterotoxigenic Bacteroides fragilis (ETBF), causes inflammatory diarrhea. However, asymptomatic ETBF colonization is common. Through its primary virulence factor, B. fragilis toxin (BFT), ETBF causes asymptomatic, chronic colitis in C57BL/6 mice and increased colon tumorigenesis in multiple intestinal neoplasia mice. Human studies suggest an association between ETBF infection, inflammatory bowel disease, and colon cancer. Additional studies on ETBF epidemiology are, therefore, crucial. The goal of this study is to develop a reliable fecal diagnostic for ETBF. To develop a sensitive assay for ETBF, we tested multiple protocols on mouse stools spiked with serially diluted ETBF. Each assay was based on either touchdown or quantitative polymerase chain reaction (qPCR) and used primers targeted to bft to detect ETBF. Using touchdown PCR or qPCR, the mean ETBF detection limit was 1.55 × 10(6) colony-forming units (CFU)/g stool and 1.33 × 10(4) CFU/g stool, respectively. Augmentation of Bacteroides spp. growth in fecal samples using PYGB (Peptone Yeast Glucose with Bile) broth enhanced ETBF detection to 2.93 × 10(2) CFU/g stool using the touchdown PCR method and 2.63 × 10(2) CFU/g stool using the qPCR method. Fecal testing using combined culture-based amplification and bft touchdown PCR is a sensitive assay for the detection of ETBF colonization and should be useful in studying the role of ETBF colonization in intestinal diseases, such as inflammatory bowel disease and colon cancer. We conclude that touchdown PCR with culture-based amplification may be the optimal ETBF detection strategy, as it performs as well as qPCR with culture-based amplification, but is a less expensive technique.

Progression of Cancer Cachexia Alters Muscle Lactate Metabolism In ApcMin/+ Mice

Roughly 100,000 individuals are diagnosed with colorectal cancer a year, 80% of these cases arise from adenomatous polyps. A mutation of the tumor suppressor gene, Adenomatous polyposis coli (Apc) results in multiple intestinal neoplasia (Min), thus the Apc (Min/+) mouse is a common colorectal cancer model. Cancer cells favor a highly glycolytic environment. As such, there is an induction of processes regulating lactate metabolism and lactate shuttling. How colorectal cancer influences skeletal muscle lactate metabolism is uncertain. Purpose: We investigated how muscle lactate metabolism is regulated during the progression of cancer cachexia in Apc (Min/+) mice. Methods: Male Min/+mice (n = 17) were classified by body mass loss: weight stable (WS, 蠄 5%, n = 5), and cachectic (CC, 6‐19%; n = 5). C57BL/6J (B6, n = 6) served as controls. Quadriceps muscle samples were extracted and real‐time PCR was conducted to quantify lactate‐related gene expression. Results: LDH‐A was reduced 47% in the CC mice compared to the WS mice (p < 0.05), while LDH‐B was not changed with cancer cachexia progression (p = 0.09). Monocarboxylate transporter 1 (MCT1) was induced 1.9‐fold in CC mice (p < 0.05) compared to the B6 mice. MCT4 was induced 1.7‐fold and 2.3‐fold in the CC mice compared to B6 and WS mice, respectively. Muscle CD147 was not changed with cancer cachexia progression (p = 0.31).ConclusionThe progression of cachexia in mice with colon cancer alters markers of lactate metabolism that may play a role in muscle wasting associated with cachexia.