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In the colorectal cancer (CRC) niche, the transcription factors signal transducer and activator of transcription 3 (STAT3) and nuclear factor‐κB (NF‐κB) are hyperactivated in both malignant cells and tumor‐infiltrating leukocytes (TILs) and cooperate to maintain cancer cell proliferation/survival and drive protumor inflammation. Through drug repositioning studies, the anthelmintic drug rafoxanide has recently emerged as a potent and selective antitumor molecule for different types of cancer, including CRC. Here, we investigate whether rafoxanide could negatively modulate STAT3/NF‐κB and inflammation‐associated CRC. The antineoplastic effect of rafoxanide was explored in a murine model of CRC resembling colitis‐associated disease. Cell proliferation and/or STAT3/NF‐κB activation were evaluated in colon tissues taken from mice with colitis‐associated CRC, human CRC cells, and CRC patient‐derived explants and organoids after treatment with rafoxanide. The STAT3/NF‐κB activation and cytokine production/secretion were assessed in TILs isolated from CRC specimens and treated with rafoxanide. Finally, we investigated the effects of TIL‐derived supernatants cultured with or without rafoxanide on CRC cell proliferation and STAT3/NF‐κB activation. The results showed that rafoxanide restrains STAT3/NF‐κB activation and inflammation‐associated colon tumorigenesis in vivo without apparent effects on normal intestinal cells. Rafoxanide markedly reduces STAT3/NF‐κB activation in cultured CRC cells, CRC‐derived explants/organoids, and TILs. Finally, rafoxanide treatment impairs the ability of TILs to produce protumor cytokines and promote CRC cell proliferation. We report the novel observation that rafoxanide negatively affects STAT3/NF‐κB oncogenic activity at multiple levels in the CRC microenvironment. Our data suggest that rafoxanide could potentially be deployed as an anticancer drug in inflammation‐associated CRC. [ABSTRACT FROM AUTHOR]

Experimental evidence suggests that, in the inflamed gut of inflammatory bowel disease (IBD) patients, interleukin-34 (IL-34) triggers detrimental signaling pathways. Factors/mechanisms regulating IL-34 production in IBD remain poorly characterized. Bromodomain-containing 4 (BRD4), a transcriptional and epigenetic regulator, is over-expressed in IBD, and studies in cancer cells suggest that BRD4 might positively control IL-34 expression. This study aimed to assess whether, in IBD, BRD4 regulates IL-34 expression. In IBD, there was an up-regulation of both IL-34 and BRD4 compared to the controls, and the two proteins co-localized in both lamina propria mononuclear cells (LPMCs) and epithelial cells. Flow cytometry analysis of CD45+ LPMCs confirmed that the percentages of IL-34- and BRD4-co-expressing cells were significantly higher in IBD than in the controls and showed that more than 80% of the IL-34-positive CD45-LPMCs expressed BRD4. IL-34 and BRD4 were mainly expressed by T cells and macrophages. IL-34 expression was reduced in IBD LPMCs transfected with BRD4 antisense oligonucleotide and in the colons of mice with dextran sulfate sodium-induced colitis treated with JQ1, a pharmacological inhibitor of BRD4. These data indicate that BRD4 is a positive regulator of IL-34 in IBD, further supporting the pathogenic role of BRD4 in IBD-associated mucosal inflammation. [ABSTRACT FROM AUTHOR]

The editorial in the journal "Biomedicines" discusses the importance of maintaining gut homeostasis through the balance of the intestinal epithelial barrier, microbiota, and the host's immune system. The special issue focuses on the impact of environmental factors, such as the Western diet and ultra-processed food, on gut dysbiosis. Various studies explore potential therapeutic interventions, including synbiotic treatments for conditions like alcoholic liver disease and fecal microbiota transplantation for gut microbial imbalance. The editorial emphasizes the need for further research to understand the microbiota-gut-organ axis and develop personalized treatments for gut dysbiosis. [Extracted from the article]

Simple Summary: Colorectal cancer (CRC) cells are characterized by high levels of SMAD7, a protein involved in the positive control of growth and survival of cancer cells. This study aims to examine whether SMAD7 is a regulator of CRC cell migration and evaluate the underlying mechanisms. By using specific antisense oligonucleotides, we here show that knockdown of SMAD7 reduces the formation of F-ACTIN filaments and impairs CRC cell migration. Analysis of molecules involved in the control of F-ACTIN formation shows that SMAD7-deficient cells have reduced content of XIAP and this is probably related to the ability of SMAD7 to control the expression of STAT3, a transcription factor that positively regulates XIAP. Finally, we document that, in human CRC samples, there is a positive correlation between SMAD7 expression and XIAP content. Overall, these findings support the role of SMAD7 in the control of F-ACTIN filament formation and migration of CRC cells. The reorganization of the cell cytoskeleton and changes in the content of cell adhesion molecules are crucial during the metastatic spread of tumor cells. Colorectal cancer (CRC) cells express high SMAD7, a protein involved in the control of CRC cell growth. In the present study, we evaluated whether SMAD7 regulates the cytoskeleton reorganization and dynamics in CRC. Knockdown of SMAD7 with a specific antisense oligonucleotide (AS) in HCT116 and DLD1, two human CRC cell lines, reduced the migration rate and the content of F-ACTIN filaments. A gene array, real-time PCR, and Western blotting of SMAD7 AS-treated cells showed a marked down-regulation of the X-linked inhibitor of apoptosis protein (XIAP), a member of the inhibitor of apoptosis family, which has been implicated in cancer cell migration. IL-6 and IL-22, two cytokines that activate STAT3, enhanced XIAP in cancer cells, and such induction was attenuated in SMAD7-deficient cells. Finally, in human CRC, SMAD7 mRNA correlated with XIAP expression. Our data show that SMAD7 positively regulates XIAP expression and migration of CRC cells, and suggest a mechanism by which SMAD7 controls the architecture components of the CRC cell cytoskeleton. [ABSTRACT FROM AUTHOR]

Aryl hydrocarbon receptor (AHR), a transcription factor activated by many natural and synthetic ligands, represents an important mediator of the interplay between the environment and the host's immune responses. In a healthy gut, AHR activation promotes tolerogenic signals, which help maintain mucosal homeostasis. AHR expression is defective in the inflamed gut of patients with inflammatory bowel diseases (IBD), where decreased AHR signaling is supposed to contribute to amplifying the gut tissue's destructive immune–inflammatory responses. We here review the evidence supporting the role of AHR in controlling the "physiological" intestinal inflammation and summarize the data about the therapeutic effects of AHR activators, both in preclinical mouse models of colitis and in patients with IBD. [ABSTRACT FROM AUTHOR]

Background and Aims Intestinal barrier dysfunction is a hallmark of inflammatory bowel diseases [IBD], but the mechanisms that lead to such a defect are not fully understood. This study was aimed at characterising the factors involved in the defective barrier function in IBD. Methods Transcriptome analysis was performed on colon samples taken from healthy controls [CTR] and IBD patients. Expression of GATA-binding factor 6 [GATA6], a transcription factor involved in intestinal epithelial cell differentiation, was evaluated in colon samples taken from CTR and IBD patients by real-time polymerase chain reaction [PCR] and immunohistochemistry. Intestinal sections of wild-type and Gata6del mice, which exhibit a conditional Gata6 deletion in intestinal epithelial cells and which are either left untreated or receive subcutaneous indomethacin or rectal trinitrobenzene sulphonic acid, were stained with haematoxylin and eosin. In parallel, some Gata6del mice received antibiotics to deplete intestinal flora. Mucosal inflammatory cell infiltration and cytokine production were evaluated by flow cytometry and real-time PCR, respectively, and tight junction proteins were examined by immunofluorescence. Intestinal barrier integrity was assessed by fluorescein isothiocyanate [FITC]-dextran assay. Results Multiple genes involved in cell commitment/proliferation and wound healing were differentially expressed in IBD compared with CTR. Among these, GATA6 was significantly decreased in the IBD epithelium compared with CTR. In mice, conditional deletion of GATA6 in the intestinal epithelium induced primarily epithelial damage, diminished zonula occludens-1 expression, and enhanced intestinal permeability, ultimately resulting in bacteria-driven local immune response and enhanced susceptibility to gut inflammation. Conclusions Reduced expression of GATA6 promotes intestinal barrier dysfunction, thus amplifying intestinal inflammatory pathology. [ABSTRACT FROM AUTHOR]

Background and Aims The inflammatory bowel disease [IBD]-associated immune response is marked by excessive production of a variety of inflammatory cytokines, which are supposed to sustain and amplify the pathological process. OTUD5 is a deubiquitinating enzyme, which regulates cytokine production by both innate and adaptive immune cells. Here, we investigated the expression and role of OTUD5 in IBD. Methods OTUD5 expression was evaluated in mucosal samples of patients with Crohn's disease [CD], patients with ulcerative colitis [UC], and controls, as well as in mice with trinitrobenzene-sulphonic acid [TNBS]-induced colitis by real-time polymerase chain reaction, western blotting, immunohistochemistry, and immunofluorescence. Moreover, OTUD5 was assessed in lamina propria mononuclear cells [LPMC] stimulated with inflammatory cytokines. TNF-α, IL-6, and IL-10 were evaluated in LPMCs of IBD patients and in colitic mice transfected with a specific OTUD5 antisense oligonucleotide [AS]. Results OTUD5 protein, but not RNA, expression was increased in inflamed ileal and colonic mucosal samples of patients with CD and patients with UC as compared with controls. In IBD, OTUD5-expressing cells were abundant in both epithelial and lamina propria compartments, and non-CD3+, HLA-DR+ LPMC were one of the major sources of the protein. OTUD5 expression was enhanced by IFN-γ through a p38/MAPK-dependent mechanism, and the AS-induced knockdown of OTUD5 in LPMCs of IBD patients and colitic mice reduced TNF-α. Conclusions Our data show that OTUD5 is overexpressed in both CD and UC and suggest the involvement of such a protein in the amplification of the aberrant cytokine response in IBD. [ABSTRACT FROM AUTHOR]