Inflammation-induced Colorectal Cancer Research Articles

Interaction of the intestinal cytokines-JAKs-STAT3 and 5 axes with RNA N6-methyladenosine to promote chronic inflammation-induced colorectal cancer

Interaction of the intestinal cytokines-JAKs-STAT3 and 5 axes with RNA N6-methyladenosine to promote chronic inflammation-induced colorectal cancer

Abstract 2180: Modulation of immune infiltration patterns in inflammation-associated colorectal cancer through rice bran-based dietary strategies

Abstract The correlation between gut microbiota dysbiosis and inflammation-associated colorectal cancer (CRC) has generated considerable interest in dietary interventions targeting immune modulation. Our prior study demonstrated the colon cancer protective effects of rice bran (RB) and ex vivo Bifidobacterium longum fermented rice bran (FRB) diet intervention against azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC in gut microbiota-intact specific pathogen-free mice (SPF). RB showed higher levels of protection compared to FRB against CRC, as evidenced by diminished neoplastic lesion size and restored colonic epithelial integrity. The major objective of the present study was to leverage cutting-edge multispectral imaging technique for simultaneous detection of multiple immune cells markers and for a comprehensive analysis of distinct immune landscapes. We also performed spatial correlations within the tumor microenvironment of AOM/DSS-SPF mice undergoing RB and FRB dietary interventions. The primary focus was on T cell subtypes including cytotoxic T cells, helper T cells, regulatory T (Treg) cells, natural killer (NK) cells, NKT cells, B cells and macrophages (MΦ) subtypes (M1 MΦ, and M2 MΦ) to uncover the intricacies of the immune landscape and the interplay for CRC prevention through dietary intervention. The results indicated that RB intervention for 15 weeks led to reductions in overall T cell subtypes in the colonic tissue, particularly Treg cells, which are associated with protecting tumors against immune surveillance in CRC. On the other hand, FRB intervention also resulted in reductions in overall T cell subtypes but exhibited higher infiltration of NK cells and proinflammatory M1 macrophages in the colonic tissue after 15 weeks. While an increased presence of NK cells might be beneficial in countering CRC, the infiltration of M1 macrophages could potentially lessen the impact of FRB compared to RB intervention in CRC protection. The outcomes suggest that the better protective efficacy of non-fermented RB diets is linked to the modulation of Treg cell infiltration, whereas the efficacy of the FRB diet is to some extent limited by the presence of M1 macrophages. Overall, this study provides valuable insights into the complex immune landscape influenced by RB and FRB interventions in a murine model of inflammation-induced CRC, and a novel mechanism for the immunomodulatory effects of dietary RB interactions with gut microbiota. In the future, observing immune modulation throughout diet intervention would enhance our understanding of the role played by these immune cells. Citation Format: Robin Kumar, Lakshmi Sai Pratyusha Bugata, Md. Imtiazul Kabir, Rajesh Agarwal, Elizabeth P. Ryan, Komal Raina. Modulation of immune infiltration patterns in inflammation-associated colorectal cancer through rice bran-based dietary strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2180.

TRAF4-Mediated LAMTOR1 Ubiquitination Promotes mTORC1 Activation and Inhibits the Inflammation-Induced Colorectal Cancer Progression.

Mechanistic target of rapamycin complex 1 (mTORC1) is a conserved serine/threonine kinase that integrates various environmental signals to regulate cell growth and metabolism. mTORC1 activation requires tethering to lysosomes by the Ragulator-Rag complex. However, the dynamic regulation of the interaction between Ragulator and Rag guanosine triphosphatase (GTPase) remains unclear. In this study, that LAMTOR1, an essential component of Ragulator, is dynamically ubiquitinated depending on amino acid abundance is reported. It is found that the E3 ligase TRAF4 directly interacts with LAMTOR1 and catalyzes the K63-linked polyubiquitination of LAMTOR1 at K151. Ubiquitination of LAMTOR1 by TRAF4 promoted its binding to Rag GTPases and enhanced mTORC1 activation, K151R knock-in or TRAF4 knock-out blocks amino acid-induced mTORC1 activation and accelerates the development of inflammation-induced colon cancer. This study revealed that TRAF4-mediated LAMTOR1 ubiquitination is a regulatory mechanism for mTORC1 activation and provides a therapeutic target for diseases involving mTORC1 dysregulation.

Preventive Activity of Patchouli Alcohol Against Colorectal Cancer and Diabetes

Patchouli alcohol (PA) is a tricyclic sesquiterpene and the dominant bioactive component in oil extracted from the aerial parts of Pogostemon cablin (patchouli). It has been reported to possess diverse health-beneficial activities, including anti-inflammatory, antiobese, and anticancer activities. However, preclinical studies are required to explore the possibility of developing PA as a promising functional and promising drug for the prevention and treatment of human diseases. In this study, we used animal models to examine whether PA shows benefits in inflammation-induced colorectal cancer and obesity-induced diabetes. ApcMin/+ mice for colorectal cancer model were treated PA 0, 25 and 50 mg/kg body weight three times a week for 6 weeks along with 2% dextran sulfate sodium (DSS) in drinking water for 1 week. High-fat diet (HFD)-induced obesity mice were treated with PA 0, 25, and 50 mg/kg bodyweight three times a week for 8 weeks. Oral administration of PA to ApcMin/+ mice treated with DSS significantly suppressed formation and development of tumors in both small and large intestines. In cell culture using Caco-2 human colorectal cancer cells, treatment of culture media with PA suppressed proliferation and induced G1-phase growth arrest. In a mouse model of HFD-induced obesity, glucose tolerance tests indicated the same orally administered dose of PA to significantly reduce blood glucose. In vitro assays in differentiated C2C12 myocytes further demonstrated PA to significantly enhance glucose uptake and increase phosphorylation of 5' adenosine monophosphate-activated protein kinase and protein kinase B. This study demonstrates that PA might possess health beneficial effects on colorectal cancer and obesity-induced diabetes.

Loss of NFE2L3 protects against inflammation-induced colorectal cancer through modulation of the tumor microenvironment

We investigated the role of the NFE2L3 transcription factor in inflammation-induced colorectal cancer. Our studies revealed that Nfe2l3−/− mice exhibit significantly less inflammation in the colon, reduced tumor size and numbers, and skewed localization of tumors with a more pronounced decrease of tumors in the distal colon. CIBERSORT analysis of RNA-seq data from normal and tumor tissue predicted a reduction in mast cells in Nfe2l3−/− animals, which was confirmed by toluidine blue staining. Concomitantly, the transcript levels of Il33 and Rab27a, both important regulators of mast cells, were reduced and increased, respectively, in the colorectal tumors of Nfe2l3−/− mice. Furthermore, we validated NFE2L3 binding to the regulatory sequences of the IL33 and RAB27A loci in human colorectal carcinoma cells. Using digital spatial profiling, we found that Nfe2l3−/− mice presented elevated FOXP3 and immune checkpoint markers CTLA4, TIM3, and LAG3, suggesting an increase in Treg counts. Staining for CD3 and FOXP3 confirmed a significant increase in immunosuppressive Tregs in the colon of Nfe2l3−/− animals. Also, Human Microbiome Project (HMP2) data showed that NFE2L3 transcript levels are higher in the rectum of ulcerative colitis patients. The observed changes in the tumor microenvironment provide new insights into the molecular differences regarding colon cancer sidedness. This may be exploited for the treatment of early-onset colorectal cancer as this emerging subtype primarily displays distal/left-sided tumors.

GPR15 Facilitates Recruitment of Regulatory T Cells to Promote Colorectal Cancer.

Colorectal cancer is one of the most frequent malignancies worldwide. Despite considerable progress in early detection and treatment, there is still an unmet need for novel antitumor therapies, particularly in advanced colorectal cancer. Regulatory T cells (Treg) are increased in the peripheral blood and tumor tissue of patients with colorectal cancer. Recently, transient ablation of tumor-associated Tregs was shown to foster CD8+ T-cell-mediated antitumoral immunity in murine colorectal cancer models. However, before considering therapies on targeting Tregs in patients with cancer, detailed knowledge of the phenotype and features of tumor-associated Tregs is indispensable. Here, we demonstrate in a murine model of inflammation-induced colorectal cancer that tumor-associated Tregs are mainly of thymic origin and equipped with a specific set of molecules strongly associated with enhanced migratory properties. Particularly, a dense infiltration of Tregs in mouse and human colorectal cancer lesions correlated with increased expression of the orphan chemoattractant receptor GPR15 on these cells. Comprehensive gene expression analysis revealed that tumor-associated GPR15+ Tregs have a Th17-like phenotype, thereby producing IL17 and TNFα. Gpr15 deficiency repressed Treg infiltration in colorectal cancer, which paved the way for enhanced antitumoral CD8+ T-cell immunity and reduced tumorigenesis. In conclusion, GPR15 represents a promising novel target for modifying T-cell-mediated antitumoral immunity in colorectal cancer. SIGNIFICANCE: The G protein-coupled receptor 15, an unconventional chemokine receptor, directs Tregs into the colon, thereby modifying the tumor microenvironment and promoting intestinal tumorigenesis.See related commentary by Chakraborty and Zappasodi, p. 2817.

Thrombocytosis and Effects of IL-6 Knock-Out in a Colitis-Associated Cancer Model.

There is an increasing number of studies showing that thrombocytosis—accompanying a variety of solid tumors including colorectal cancer (CRC)—is associated with shorter survival and earlier development of metastases. The mechanisms of cancer-associated thrombocytosis are not completely understood yet. The aim of our study was to evaluate the role of IL-6 in tumor development and thrombocytosis in mice with inflammation-induced CRC, using a CRISPR/cas9 IL-6 knockout (KO) strain. Adult male FB/Ant mice (n = 39) were divided into four groups: (1) IL-6 KO controls (n = 5); (2) IL-6 KO CRC model group (n = 18); (3) Wild-type (WT) controls (n = 6); and (4) WT CRC model group (n = 10). CRC model animals in (2) and (4) received azoxymethane (AOM)/dextran sodium sulfate (DSS) treatment to induce inflammation-related CRC. Plasma and liver tissues were obtained to determine platelet counts, IL-6 and thrombopoietin-1 (TPO) levels. In 1 WT and 2 IL-6 KO mice in vivo confocal endomicroscopy and 18F-fluorodeoxyglucose (FDG) PET/MRI examinations were performed to evaluate the inflammatory burden and neoplastic transformation. At the end of the study, tumorous foci could be observed macroscopically in both CRC model groups. Platelet counts were significantly elevated in the WT CRC group compared to the IL-6 KO CRC group. TPO levels moved parallelly with platelet counts. In vivo fluorescent microscopy showed signs of disordered and multi-nuclear crypt morphology with increased mucus production in a WT animal, while regular mucosal structure was prominent in the IL-6 KO animals. The WT animal presented more intense and larger colonic FDG uptake than IL-6 KO animals. Our study confirmed thrombocytosis accompanying inflammation-related CRC and the crucial role of IL-6 in this process. Significantly higher platelet counts were found in the WT CRC group compared to both the control group and the IL-6 KO group. Concomitantly, the tumor burden of WT mice was also greater than that of IL-6 KO mice. Our findings are in line with earlier paraneoplastic IL-6 effect suggestions.

Toll-like Receptor-6 Signaling Prevents Inflammation and Impacts Composition of the Microbiota During Inflammation-Induced Colorectal Cancer.

Tightly regulated immune responses must occur in the intestine to avoid unwanted inflammation, which may cause chronic sequela leading to diseases such as colorectal cancer. Toll-like receptors play an important role in preventing aberrant immune responses in the intestine by sensing endogenous commensal microbiota and delivering important regulatory signals to the tissue. However, the role that specific innate receptors may play in the development of chronic inflammation and their impact on the composition of the colonic microbiota is not well understood. Using a model of inflammation-induced colorectal cancer, we found that Lactobacillus species are lost more quickly in wild-type (WT) mice than TLR6-deficient mice resulting in overall differences in bacterial composition. Despite the longer retention of Lactobacillus, the TLR6-deficient mice presented with more tumors and a worse overall outcome. Restoration of the lost Lactobacillus species suppressed inflammation, reduced tumor number, and prevented change in the abundance of Proteobacteria only when given to WT mice, indicating the effect of these Lactobacillus are TLR6 dependent. We found that the TLR6-dependent effects of Lactobacillus could be dissociated from one another via the involvement of IL10, which was necessary to dampen the inflammatory microenvironment, but had no effect on bacterial composition. Altogether, these data suggest that innate immune signals can shape the composition of the microbiota under chronic inflammatory conditions, bias the cytokine milieu of the tissue microenvironment, and influence the response to microbiota-associated therapies.

Obacunone reduces inflammatory signalling and tumour occurrence in mice with chronic inflammation-induced colorectal cancer

Context Obacunone, a limonoid abundantly found in Citrus fruits, exhibits a variety of bioactivities. Objective To investigate the effects of obacunone on a colorectal cancer (CRC) mouse model, and clarify its potential molecular mechanisms. Materials and methods The male Balb/c mice were induced with azoxymethane and dextran sulfate sodium for 12 weeks. Obacunone (50 mg/kg) was administered via oral gavage three times every week until the end of the experiment. Disease indexes including body weight, spleen weight, bloody diarrhea, colon length, histopathological score, and tumor size were measured. The anti-proliferation activities of obacunone were analyzed by MTT or flow cytometry. The expression of protein and mRNA related to cell proliferation or inflammatory cytokines was determined by Western blot, q-PCR and IHC. Results Obacunone significantly alleviated bloody diarrhea, colon shortening (7.35 ± 0.2128 vs. 8.275 ± 0.2169 cm), splenomegaly, histological score (9 ± 0.5774 vs. 6 ± 0.5774) and reduced tumor size (4.25 ± 0.6196 vs. 2 ± 0.5669). Meanwhile, the expression of protein and mRNA related to cell proliferation or inflammatory cytokines was remarkably decreased in tumor tissue. Obacunone inhibited the proliferation activities of colorectal cancer cells. Moreover, obacunone induced colorectal cancer cells G1 and G2 phases arrest, and suppressed the expression of cell cycle genes. Conclusions Obacunone could alleviate CRC via inhibiting inflammatory response and tumor cells proliferation. The results may contribute to the effective utilization of obacunone or its derivatives in the treatment of human CRC.

Neutrophils Deficient in Innate Suppressor IRAK-M Enhances Anti-tumor Immune Responses.

Tumor-associated immune-suppressive neutrophils are prevalent in various cancers, including colorectal cancer. However, mechanisms of immune-suppressive neutrophils are not well understood. We report that a key innate suppressor, IRAK-M (interleukin-1 receptor-associated kinase M), is critically involved in the establishment of immune-suppressive neutrophils. In contrast to the wild-type (WT) neutrophils exhibiting immune-suppressive signatures of CD11bhighPD-L1highCD80low, IRAK-M-deficient neutrophils are rewired with reduced levels of inhibitory molecules PD-L1 and CD11b, as well as enhanced expression of stimulatory molecules CD80 and CD40. The reprogramming of IRAK-M-deficient neutrophils is mediated by reduced activation of STAT1/3 and enhanced activation of STAT5. As a consequence, IRAK-M-deficient neutrophils demonstrate enhanced capability to promote, instead of suppress, the proliferation and activation of effector Tcells both invitro and invivo. Functionally, we observed that the transfusion of IRAK-M-/- neutrophils can potently render an enhanced anti-tumor immune response in the murine inflammation-induced colorectal cancer model. Collectively, our study defines IRAK-M as an innate suppressor for neutrophil function and reveals IRAK-M as a promising target for rewiring neutrophils in anti-cancer immunotherapy.

CD36 inhibits \u03b2-catenin/c-myc-mediated glycolysis through ubiquitination of GPC4 to repress colorectal tumorigenesis

The diverse expression pattern of CD36 reflects its multiple cellular functions. However, the roles of CD36 in colorectal cancer (CRC) remain unknown. Here, we discover that CD36 expression is progressively decreased from adenomas to carcinomas. CD36 loss predicts poor survival of CRC patients. In CRC cells, CD36 acts as a tumor suppressor and inhibits aerobic glycolysis in vitro and in vivo. Mechanically, CD36-Glypcian 4 (GPC4) interaction could promote the proteasome-dependent ubiquitination of GPC4, followed by inhibition of β-catenin/c-myc signaling and suppression of downstream glycolytic target genes GLUT1, HK2, PKM2 and LDHA. Moreover, disruption of CD36 in inflammation-induced CRC model as well as ApcMin/+ mice model significantly increased colorectal tumorigenesis. Our results reveal a CD36-GPC4-β-catenin-c-myc signaling axis that regulates glycolysis in CRC development and may provide an intervention strategy for CRC prevention.

Upregulation of PD-1 follows tumour development in the AOM/DSS model of inflammation-induced colorectal cancer in mice.

Chronic inflammation may drive development of cancer as observed in inflammation-induced colorectal cancer (CRC). Though immune cells can infiltrate the tumour microenvironment, cancer cells seem to evade anti-tumour responses, which is one of the established hallmarks of cancer. Targeting the programmed cell death protein-1 (PD-1)/PD-L1 signalling pathway is currently at the forefront in the development of anti-tumour immunity-based therapies for multiple malignancies. By blocking the immune-checkpoint of activated T-cells, it is possible to rewire the adaptive resistance induced by the PD-1 ligands expressed in the tumour microenvironment. However, adverse immunotherapy-modulated events could complicate the treatment of individuals with preexisting chronic inflammatory conditions. In this study, we investigated the expression of different systemic and mucosal T-cell subsets during the course of azoxymethane (AOM)/dextran sulphate sodium (DSS)-induced colitis and colitis-associated CRC. In addition, we examined the expression of PD-1 and its ligands PD-L1 and PD-L2 as well as other molecular targets related to T-cell exhaustion. We found a significant increase in PD-1 expression on all examined mucosal T-cell subsets of the colon and the ileum, which correlated with disease progression. We also observed an upregulation of PD-L1 and PD-L2 mRNA expression throughout the AOM/DSS regime. Blocking PD-1 signalling with an anti-PD1 antibody did not affect the tumour burden in the AOM/DSS-treated mice, but did potentiate the weight loss in the third DSS cycle, indicating possible immune-mediated toxicity. This raises a concern for patients with colitis-associated CRCs and should be further investigated.

Role of epigenetics in transformation of inflammation into colorectal cancer

Molecular mechanisms associated with inflammation-promoted tumorigenesis have become an important topic in cancer research. Various abnormal epigenetic changes, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA regulation, occur during the transformation of chronic inflammation into colorectal cancer (CRC). These changes not only accelerate transformation but also lead to cancer progression and metastasis by activating carcinogenic signaling pathways. The NF-κB and STAT3 signaling pathways play a particularly important role in the transformation of inflammation into CRC, and both are critical to cellular signal transduction and constantly activated in cancer by various abnormal changes including epigenetics. The NF-κB and STAT3 signals contribute to the microenvironment for tumorigenesis through secretion of a large number of pro-inflammatory cytokines and their crosstalk in the nucleus makes it even more difficult to treat CRC. Compared with gene mutation that is irreversible, epigenetic inheritance is reversible or can be altered by the intervention. Therefore, understanding the role of epigenetic inheritance in the inflammation-cancer transformation may elucidate the pathogenesis of CRC and promote the development of innovative drugs targeting transformation to prevent and treat this malignancy. This review summarizes the literature on the roles of epigenetic mechanisms in the occurrence and development of inflammation-induced CRC. Exploring the role of epigenetics in the transformation of inflammation into CRC may help stimulate futures studies on the role of molecular therapy in CRC.

Activated Eosinophils Exert Antitumorigenic Activities in Colorectal Cancer.

Immunotherapies targeting T lymphocytes are revolutionizing cancer therapy but only benefit a subset of patients, especially in colorectal cancer. Thus, additional insight into the tumor microenvironment (TME) is required. Eosinophils are bone marrow-derived cells that have been largely studied in the context of allergic diseases and parasite infections. Although tumor-associated eosinophilia has been described in various solid tumors including colorectal cancer, knowledge is still missing regarding eosinophil activities and even the basic question of whether the TME promotes eosinophil recruitment without additional manipulation (e.g., immunotherapy) is unclear. Herein, we report that eosinophils are recruited into developing tumors during induction of inflammation-induced colorectal cancer and in mice with the Apcmin /+ genotype, which develop spontaneous intestinal adenomas. Using adoptive transfer and cytokine neutralization experiments, we demonstrate that the TME supported prolonged eosinophil survival independent of IL5, an eosinophil survival cytokine. Tumor-infiltrating eosinophils consisted of degranulating eosinophils and were essential for tumor rejection independently of CD8+ T cells. Transcriptome and proteomic analysis revealed an IFNγ-linked signature for intratumoral eosinophils that was different from that of macrophages. Our data establish antitumorigenic roles for eosinophils in colorectal cancer. These findings may facilitate the development of pharmacologic treatments that could unleash antitumor responses by eosinophils, especially in colorectal cancer patients displaying eosinophilia.

Transmissible inflammation-induced colorectal cancer in inflammasome-deficient mice

ABSTRACTThe microbiota is pivotal in orchestrating the pathogenesis of IBD-associated colorectal cancer (CRC). We recently demonstrated that altered elements in the microbiota of inflammasome-deficient mice drive transmissible inflammation-induced CRC. This microbiota-mediated effect is dependent upon microbiome-induced CCL5-driven inflammation, which, in turn, promotes epithelial cell proliferation through local activation of the IL-6 pathway, leading to cancer development.

Cytoglobin affects tumorigenesis and the expression of ulcerative colitis-associated genes under chemically induced colitis in mice

Cytoglobin (Cygb) is a member of the hemoglobin family and is thought to protect against cellular hypoxia and oxidative stress. These functions may be particularly important in inflammation-induced cancer, e.g., in patients with ulcerative colitis (UC). In this study, we investigated the development of inflammation and tumors in a murine model of inflammation-induced colorectal cancer using a combined treatment of azoxymethane and dextran sulfate sodium. A bioinformatics analysis of genome-wide expression data revealed increased colonic inflammation at the molecular level accompanied by enhanced macroscopic tumor development in Cygb-deficient mice. Moreover, the expression of the UC-associated gene neurexophilin and PC-esterase domain family member 4 (Nxpe4) depended on the presence of Cygb in the inflamed colonic mucosa. Compared to wild type mice, RT-qPCR confirmed a 14-fold (p = 0.0003) decrease in Nxpe4 expression in the inflamed colonic mucosa from Cygb-deficient mice. An analysis of Cygb protein expression suggested that Cygb is expressed in fibroblast-like cells surrounding the colonic crypts. Histological examinations of early induced lesions suggested that the effect of Cygb is primarily at the level of tumor promotion. In conclusion, in this model, Cygb primarily seemed to inhibit the development of established microadenomas.

MTORC1 Inactivation Promotes Colitis-Induced Colorectal Cancer but Protects from APC Loss-Dependent Tumorigenesis

Dietary habits that can induce inflammatory bowel disease (IBD) are major colorectal cancer (CRC) risk factors, but mechanisms linking nutrients, IBD, and CRC are unknown. Using human data and mouse models, we show that mTORC1 inactivation-induced chromosomal instability impairs intestinal crypt proliferation and regeneration, CDK4/6 dependently. This triggers interleukin (IL)-6-associated reparative inflammation, inducing crypt hyper-proliferation, wound healing, and CRC. Blocking IL-6 signaling or reactivating mTORC1 reduces inflammation-induced CRC, so mTORC1 activation suppresses tumorigenesis in IBD. Conversely, mTORC1 inactivation is beneficial in APC loss-dependent CRC. Thus, IL-6 blockers or protein-rich-diet-linked mTORC1 activation may prevent IBD-associated CRC. However, abolishing mTORC1 can mitigate CRC in predisposed patients with APC mutations. Our work reveals mTORC1 oncogenic and tumor-suppressive roles in intestinal epithelium and avenues to optimized and personalized therapeutic regimens for CRC.

Wild mouse gut microbiome protects laboratory mice against lethal influenza virus infection and colorectal cancer

Abstract Mouse models are paramount for understanding basic immunological mechanisms, but can be limited in recapitulating human diseases. The microbiome has been identified as a main factor influencing host physiology as illustrated by many studies that disrupt or modify host-microbe interactions in laboratory mice. Differences in the gut microbiome contribute to the variability of research results obtained with genetically identical animals from different vendors. In an effort to identify an external reference that better recapitulates physiologically important interactions found in a natural habitat, we asked how far removed the gut microbiome of laboratory mice is from that of their outbred, wild-living relative. Through genetic analysis we identify the closest wild relatives to classical laboratory strains among 21 distinct populations from Europe, Asia and the Americas. We establish that their gut microbiome differs significantly from that of C57BL/6 mice from the leading breeders worldwide, and that it can be transferred and maintained over several generations under vivarium conditions. Offspring of pregnant germ-free C57BL/6 mice reconstituted with the gut microbiome of wild mice exhibit a significantly reduced inflammatory response and increased survival following influenza A virus infection. This restoration of the natural ‘microbial identity’ of laboratory mice also improved their resistance against mutagen- and inflammation-induced colorectal cancer. Collectively, these data show the beneficial effects of the wild mouse microbiome in two diseases of global relevance. They also illustrate a novel approach towards developing animal models of greater biological relevance and translational research value.

GFI1 downregulation promotes inflammation-linked metastasis of colorectal cancer

Inflammation is frequently associated with initiation, progression, and metastasis of colorectal cancer (CRC). Here, we unveil a CRC-specific metastatic programme that is triggered via the transcriptional repressor, GFI1. Using data from a large cohort of clinical samples including inflammatory bowel disease and CRC, and a cellular model of CRC progression mediated by cross-talk between the cancer cell and the inflammatory microenvironment, we identified GFI1 as a gating regulator responsible for a constitutively activated signalling circuit that renders CRC cells competent for metastatic spread. Further analysis of mouse models with metastatic CRC and human clinical specimens reinforced the influence of GFI1 downregulation in promoting CRC metastatic spread. The novel role of GFI1 is uncovered for the first time in a human solid tumour such as CRC. Our results imply that GFI1 is a potential therapeutic target for interfering with inflammation-induced CRC progression and spread.

Claudin-1 promotes TNF-α-induced epithelial-mesenchymal transition and migration in colorectal adenocarcinoma cells

Epithelial-mesenchymal transition (EMT) is an important mechanism in cancer progression and malignancy including colorectal cancer (CRC). Importantly, inflammatory mediators are critical constituents of the local tumor environment and an intimate link between CRC progression and inflammation is now validated. We and others have reported key role of the deregulated claudin-1 expression in colon carcinogenesis including colitis-associated colon cancer (CAC). However, the causal association between claudin-1 expression and inflammation-induced colon cancer progression remains unclear. Here we demonstrate, TNF-α, a pro-inflammatory cytokine, regulates claudin-1 to modulate epithelial to mesenchymal transition (EMT) and migration in colon adenocarcinoma cells. Importantly, colon cancer cells cultured in the presence of TNF-α (10ng/ml), demonstrated a sharp decrease in E-cadherin expression and an increase in vimentin expression (versus control cells). Interestingly, TNF-α treatment also upregulated (and delocalized) claudin-1 expression in a time-dependent manner accompanied by increase in proliferation and wound healing. Furthermore, similar to our previous observation that claudin-1 overexpression in CRC cells induces ERK1/2 and Src- activation, signaling associated with colon cancer cell survival and transformation, TNF-α-treatment induced upregulation of phospho-ERK1/2 and -Src expression. The shRNA-mediated inhibition of claudin-1 expression largely abrogated the TNF-α-induced changes in EMT, proliferation, migration, p-Erk and p-Src expression. Taken together, our data demonstrate TNF-α mediated regulation of claudin-1 and tumorigenic abilities of colon cancer cells and highlights a key role of deregulated claudin-1 expression in inflammation-induced colorectal cancer growth and progression, through the regulation of the ERK and Src-signaling.