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Gastroenterology Feb 2024Dietary fibers are mainly fermented by the gut microbiota, but their roles in colorectal cancer (CRC) are largely unclear. Here, we investigated the associations of...
BACKGROUND & AIMS
Dietary fibers are mainly fermented by the gut microbiota, but their roles in colorectal cancer (CRC) are largely unclear. Here, we investigated the associations of different fibers with colorectal tumorigenesis in mice.
METHODS
Apc mice and C57BL/6 mice with azoxymethane (AOM) injection were used as CRC mouse models. Mice were fed with mixed high-fiber diet (20% soluble fiber and 20% insoluble fiber), high-inulin diet, high-guar gum diet, high-cellulose diet, or diets with different inulin dose. Germ-free mice were used for validation. Fecal microbiota and metabolites were profiled by shotgun metagenomic sequencing and liquid chromatography-mass spectrometry, respectively.
RESULTS
Mixed high-fiber diet promoted colorectal tumorigenesis with increased tumor number and tumor load in AOM-treated and Apc mice. Antibiotics use abolished the pro-tumorigenic effect of mixed high-fiber diet, while transplanting stools from mice fed with mixed high-fiber diet accelerated tumor growth in AOM-treated germ-free mice. We therefore characterized the contribution of soluble and insoluble fiber in CRC separately. Our results revealed that soluble fiber inulin or guar gum, but not insoluble fiber cellulose, promoted colorectal tumorigenesis in AOM-treated and Apc mice. Soluble fiber induced gut dysbiosis with Bacteroides uniformis enrichment and Bifidobacterium pseudolongum depletion, accompanied by increased fecal butyrate and serum bile acids and decreased inosine. We also identified a positive correlation between inulin dosage and colorectal tumorigenesis. Moreover, transplanting stools from mice fed with high-inulin diet increased colonic cell proliferation and oncogene expressions in germ-free mice.
CONCLUSION
High-dose soluble but not insoluble fiber potentiates colorectal tumorigenesis in a dose-dependent manner by dysregulating gut microbiota and metabolites in mice.
Topics: Mice; Animals; Gastrointestinal Microbiome; Inulin; Mice, Inbred C57BL; Carcinogenesis; Dietary Fiber; Cellulose; Azoxymethane; Colorectal Neoplasms
PubMed: 37858797
DOI: 10.1053/j.gastro.2023.10.012 -
Journal For Immunotherapy of Cancer Jan 2021Poly(ADP-ribose) polymerase (PARP) inhibitors (eg, olaparib) are effective against BRCA-mutated cancers at/near maximum tolerated doses by trapping PARP-1 on damaged...
BACKGROUND
Poly(ADP-ribose) polymerase (PARP) inhibitors (eg, olaparib) are effective against BRCA-mutated cancers at/near maximum tolerated doses by trapping PARP-1 on damaged chromatin, benefitting only small patient proportions. The benefits of targeting non-DNA repair aspects of PARP with metronomic doses remain unexplored.
METHODS
Colon epithelial cells or mouse or human bone marrow (BM)-derived-myeloid-derived suppressor cells (MDSCs) were stimulated to assess the effect of partial PARP-1 inhibition on inflammatory gene expression or immune suppression. Mice treated with azoxymethane/four dextran-sulfate-sodium cycles or mice bred into PARP-1 or treated with olaparib were used to examine the role of PARP-1 in colitis-induced or spontaneous colon cancer, respectively. Syngeneic MC-38 cell-based (microsatellite instability, MSI) or CT-26 cell-based (microsatellite stable, MSS) tumor models were used to assess the effects of PARP inhibition on host responses and synergy with anti-Programmed cell Death protein (PD)-1 immunotherapy.
RESULTS
Partial PARP-1 inhibition, via gene heterozygosity or a moderate dose of olaparib, protected against colitis-mediated/ -mediated intestinal tumorigenesis and -associated cachexia, while extensive inhibition, via gene knockout or a high dose of olaparib, was ineffective or aggravating. A sub-IC50-olaparib dose or PARP-1 heterozygosity was sufficient to block tumorigenesis in a syngeneic colon cancer model by modulating the suppressive function, but not intratumoral migration or differentiation, of MDSCs, with concomitant increases in intratumoral T cell function and cytotoxicity, as assessed by granzyme-B/interferon-γ levels. Adoptive transfer of WT-BM-MDSCs abolished the protective effects of PARP-1 heterozygosity. The mechanism of MDSC modulation involved a reduction in arginase-1/inducible nitric oxide synthase/cyclo-oxygenase-2, but independent of PARP-1 trapping on chromatin. Although a high-concentration olaparib or the high-trapping PARP inhibitor, talazoparib, activated stimulator of interferon gene (STING) in BRCA-proficient cells and induced DNA damage, sub-IC50 concentrations of either drug failed to induce activation of the dsDNA break sensor. STING expression appeared dispensable for MDSC suppressive function and was not strictly required for olaparib-mediated effects. Ironically, STING activation blocked human and mouse MDSC function with no additive effects with olaparib. A metronomic dose of olaparib was highly synergistic with anti-PD-1-based immunotherapy, leading to eradication of MSI or reduction of MSS tumors in mice.
CONCLUSIONS
These results support a paradigm-shifting concept that expands the utility of PARP inhibitor and encourage testing metronomic dosing of PARP inhibitor to enhance the efficacy of checkpoint inhibitor-based immunotherapies in cancer.
Topics: Administration, Metronomic; Animals; Azoxymethane; Cell Line, Tumor; Colitis; Colonic Neoplasms; Dextran Sulfate; Drug Synergism; Humans; Immune Checkpoint Inhibitors; Mice; Myeloid-Derived Suppressor Cells; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Xenograft Model Antitumor Assays
PubMed: 33495297
DOI: 10.1136/jitc-2020-001643 -
International Journal of Molecular... May 2022Colitis is a major risk factor for the development of colorectal cancer, leading to colitis-associated colorectal cancer (CAC). The most commonly used animal model to... (Observational Study)
Observational Study
Colitis is a major risk factor for the development of colorectal cancer, leading to colitis-associated colorectal cancer (CAC). The most commonly used animal model to study CAC is the azoxymethane-dextran sulphate-sodium (AOM/DSS) model. The ideal experimental conditions of this model depend on several factors, including the used mouse strain. No data on feasibility and conditions for older mice, e.g., for aging studies, have yet been reported. Thus, we conducted a descriptive, observational pilot study where CAC was induced in 14-month-old female Balb/C and C57/Bl6 mice using 12.5 mg/kg AOM i.p. and three different concentrations of DSS (1, 2, and 3%) in drinking water (ad. lib.). The mice were monitored regularly during the three-month experimental phase. After euthanasia, the colons of the mice were evaluated macroscopically and microscopically. Both the mouse strains showed a DSS-concentration-dependent induction of CAC. Carcinomas were only observed at 3% DSS. The DSS dose was found to be significantly correlated with the histology score and % Ki67 positive cells only in C57/Bl6 mice but not in Balb/C mice, which showed a variable response to the CAC induction. No differences in colon length, weight, or mucin content were observed. Optimal conditions for CAC induction in these aged animals are thus considered to be 3% DSS, as carcinomas did not develop when 2% DSS was used. On the other hand, Balb/C mice reacted severely to 3% DSS, indicating that 2.5% DSS may be the "sweet spot" for future experiments comparing CAC in aged Balb/C and C57/Bl6 mice. This model will allow investigation of the effect of aging on CAC development and therapy.
Topics: Animals; Azoxymethane; Carcinogenesis; Carcinoma; Colitis; Colitis-Associated Neoplasms; Colorectal Neoplasms; Dextran Sulfate; Disease Models, Animal; Female; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Pilot Projects
PubMed: 35563665
DOI: 10.3390/ijms23095278 -
Gastroenterology Mar 2021RNA N-methyladenosine (mA) modification has recently emerged as a new regulatory mechanism in cancer progression. We aimed to explore the role of the mA regulatory... (Observational Study)
Observational Study
BACKGROUND & AIMS
RNA N-methyladenosine (mA) modification has recently emerged as a new regulatory mechanism in cancer progression. We aimed to explore the role of the mA regulatory enzyme METTL3 in colorectal cancer (CRC) pathogenesis and its potential as a therapeutic target.
METHODS
The expression and clinical implication of METTL3 were investigated in multiple human CRC cohorts. The underlying mechanisms of METTL3 in CRC were investigated by integrative mA sequencing, RNA sequencing, and ribosome profiling analyses. The efficacy of targeting METTL3 in CRC treatment was elucidated in CRC cell lines, patient-derived CRC organoids, and Mettl3-knockout mouse models.
RESULTS
Using targeted clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 dropout screening, we identified METTL3 as the top essential mA regulatory enzyme in CRC. METTL3 was overexpressed in 62.2% (79/127) and 88.0% (44/50) of primary CRCs from 2 independent cohorts. High METTL3 expression predicted poor survival in patients with CRC (n = 374, P < .01). Functionally, silencing METTL3 suppressed tumorigenesis in CRC cells, human-derived primary CRC organoids, and Mettl3-knockout mouse models. We discovered the novel functional mA methyltransferase domain of METTL3 in CRC cells by domain-focused CRISPR screening and mutagenesis assays. Mechanistically, METTL3 directly induced the mA-GLUT1-mTORC1 axis as identified by integrated mA sequencing, RNA sequencing, ribosome sequencing, and functional validation. METTL3 induced GLUT1 translation in an mA-dependent manner, which subsequently promoted glucose uptake and lactate production, leading to the activation of mTORC1 signaling and CRC development. Furthermore, inhibition of mTORC1 potentiated the anticancer effect of METTL3 silencing in CRC patient-derived organoids and METTL3 transgenic mouse models.
CONCLUSIONS
METTL3 promotes CRC by activating the mA-GLUT1-mTORC1 axis. METTL3 is a promising therapeutic target for the treatment of CRC.
Topics: Adenosine; Aged; Animals; Azoxymethane; Carcinogenesis; Cell Line, Tumor; Cohort Studies; Colorectal Neoplasms; DNA Methylation; Dextran Sulfate; Female; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Glucose Transporter Type 1; Humans; Male; Mechanistic Target of Rapamycin Complex 1; Methyltransferases; Mice, Knockout; Middle Aged; Neoplasms, Experimental; Signal Transduction; Up-Regulation; Mice
PubMed: 33217448
DOI: 10.1053/j.gastro.2020.11.013 -
Gastroenterology Jul 2021Sulfation is a conjugation reaction essential for numerous biochemical and cellular functions in mammals. The 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthase 2...
BACKGROUND & AIMS
Sulfation is a conjugation reaction essential for numerous biochemical and cellular functions in mammals. The 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthase 2 (PAPSS2) is the key enzyme to generate PAPS, which is the universal sulfonate donor for all sulfation reactions. The goal of this study was to determine whether and how PAPSS2 plays a role in colitis and colonic carcinogenesis.
METHODS
Tissue arrays of human colon cancer specimens, gene expression data, and clinical features of cancer patients were analyzed. Intestinal-specific Papss2 knockout mice (Papss2) were created and subjected to dextran sodium sulfate-induced colitis and colonic carcinogenesis induced by a combined treatment of azoxymethane and dextran sodium sulfate or azoxymethane alone.
RESULTS
The expression of PAPSS2 is decreased in the colon cancers of mice and humans. The lower expression of PAPSS2 in colon cancer patients is correlated with worse survival. Papss2 mice showed heightened sensitivity to colitis and colon cancer by damaging the intestinal mucosal barrier, increasing intestinal permeability and bacteria infiltration, and worsening the intestinal tumor microenvironment. Mechanistically, the Papss2 mice exhibited reduced intestinal sulfomucin content. Metabolomic analyses revealed the accumulation of bile acids, including the Farnesoid X receptor antagonist bile acid tauro-β-muricholic acid, and deficiency in the formation of bile acid sulfates in the colon of Papss2 mice.
CONCLUSIONS
We have uncovered an important role of PAPSS2-mediated sulfation in colitis and colonic carcinogenesis. Intestinal sulfation may represent a potential diagnostic marker and PAPSS2 may serve as a potential therapeutic target for inflammatory bowel disease and colon cancer.
Topics: Animals; Bile Acids and Salts; Colitis; Colitis-Associated Neoplasms; Colon; Databases, Genetic; Disease Models, Animal; Humans; Intestinal Mucosa; Metabolome; Metabolomics; Mice, Inbred C57BL; Mice, Knockout; Mucins; Multienzyme Complexes; Prognosis; Receptors, Cytoplasmic and Nuclear; Sulfate Adenylyltransferase; Mice
PubMed: 33819483
DOI: 10.1053/j.gastro.2021.03.048 -
Gastroenterology Feb 2021Chronic colonic inflammation leads to dysplasia and cancer in patients with inflammatory bowel disease. We have described the critical role of innate immune signaling...
BACKGROUND & AIMS
Chronic colonic inflammation leads to dysplasia and cancer in patients with inflammatory bowel disease. We have described the critical role of innate immune signaling via Toll-like receptor 4 (TLR4) in the pathogenesis of dysplasia and cancer. In the current study, we interrogate the intersection of TLR4 signaling, epithelial redox activity, and the microbiota in colitis-associated neoplasia.
METHODS
Inflammatory bowel disease and colorectal cancer data sets were analyzed for expression of TLR4, dual oxidase 2 (DUOX2), and NADPH oxidase 1 (NOX1). Epithelial production of hydrogen peroxide (HO) was analyzed in murine colonic epithelial cells and colonoid cultures. Colorectal cancer models were carried out in villin-TLR4 mice, carrying a constitutively active form of TLR4, their littermates, and villin-TLR4 mice backcrossed to DUOXA-knockout mice. The role of the TLR4-shaped microbiota in tumor development was tested in wild-type germ-free mice.
RESULTS
Activation of epithelial TLR4 was associated with up-regulation of DUOX2 and NOX1 in inflammatory bowel disease and colorectal cancer. DUOX2 was exquisitely dependent on TLR4 signaling and mediated the production of epithelial HO. Epithelial HO was significantly increased in villin-TLR4 mice; TLR4-dependent tumorigenesis required the presence of DUOX2 and a microbiota. Mucosa-associated microbiota transferred from villin-TLR4 mice to wild-type germ-free mice caused increased HO production and tumorigenesis.
CONCLUSIONS
Increased TLR4 signaling in colitis drives expression of DUOX2 and epithelial production of HO. The local milieu imprints the mucosal microbiota and imbues it with pathogenic properties demonstrated by enhanced epithelial reactive oxygen species and increased development of colitis-associated tumors. The inter-relationship between epithelial reactive oxygen species and tumor-promoting microbiota requires a 2-pronged strategy to reduce the risk of dysplasia in colitis patients.
Topics: Animals; Azoxymethane; Carcinogenesis; Colitis, Ulcerative; Colitis-Associated Neoplasms; Colon; Datasets as Topic; Dextran Sulfate; Disease Models, Animal; Dual Oxidases; Gastrointestinal Microbiome; Germ-Free Life; Humans; Hydrogen Peroxide; Intestinal Mucosa; Membrane Proteins; Mice; Mice, Knockout; NADPH Oxidase 1; Toll-Like Receptor 4
PubMed: 33127391
DOI: 10.1053/j.gastro.2020.10.031 -
Molecular Metabolism Sep 2023Sufficient evidence has linked many different types of cancers and T2D through shared risk factors; however, the underlying mechanisms are not fully understood....
Sufficient evidence has linked many different types of cancers and T2D through shared risk factors; however, the underlying mechanisms are not fully understood. α-Hydroxybutyrate (α-HB), a byproduct metabolite increased in diabetes and cancer, including colorectal cancer (CRC), triggers lactate dehydrogenase A (LDHA) nuclear translocation. Nuclear LDHA markedly extends NF-κB nuclear retention by interacting with phosphorylated p65, leading to an increase in TNF-α production, impaired insulin secretion and the exacerbation of azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC and high-fat diet (HFD)-induced type 2 diabetes. Furthermore, metformin interrupted this process by inhibiting the transcription of FOXM1 and c-MYC, the resultant downregulation of LDHA expression and α-HB-induced LDHA nuclear translocation. Thus, the results reveal the elevated α-HB level could be a novel shared risk factor of linking CRC, diabetes and the use of metformin treatment, as well as highlight the importance of preventing NF-κB activation for protecting against cancer and diabetes.
Topics: Humans; NF-kappa B; Diabetes Mellitus, Type 2; Colorectal Neoplasms; Signal Transduction
PubMed: 37406987
DOI: 10.1016/j.molmet.2023.101766 -
Phytomedicine : International Journal... Dec 2023Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD), resulting from long-term inflammation in the intestines. The...
BACKGROUND
Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD), resulting from long-term inflammation in the intestines. The primary cause of CAC is the imbalance of oxidative metabolism in intestinal cells, triggered by excessive reactive oxygen (ROS) and nitrogen (NO) species production due to prolonged intestinal inflammation. This imbalance leads to genomic instability caused by DNA damage, eventually resulting in the development of intestinal cancer. Previous studies have demonstrated that astragaloside IV is effective in treating dextran sulfate sodium salt (DSS)-induced colitis, but there is currently no relevant research on its efficacy in treating CAC.
METHODS
To investigate the effect of astragaloside IV against CAC and the underlying mechanism, C57 mice were treated with (20, 40, 80 mg/kg) astragaloside IV while CAC was induced by intraperitoneal injection of 10 mg/kg azoxymethane (AOM) and ad libitum consumption of 2% dextran sulfate sodium salt (DSS). We re-verified the activating effects of astragaloside IV on PPARγ signaling in IEC-6 cells, which were reversed by GW9662 (the PPARγ inhibitor).
RESULTS
Our results showed that astragaloside IV significantly improved AOM/DSS-induced CAC mice by inhibiting colonic shortening, preventing intestinal mucosal damage, reducing the number of tumors and, the expression of Ki67 protein. In addition, astragaloside IV could activate PPARγ signaling, which not only promoted the expression of Nrf2 and HO-1, restored the level of SOD, CAT and GSH, but also inhibited the expression of iNOS and reduced the production of NO in the intestine and IEC-6 cells. And this effect could be reversed by GW9662 in vitro. Astragaloside IV thus decreased the level of ROS and NO in the intestinal tract of mice, as well as reduced the damage of DNA, and therefore inhibited the occurrence of CAC.
CONCLUSION
Astragaloside IV can activate PPARγ signaling in intestinal epithelial cells and reduces DNA damage caused by intestinal inflammation, thereby inhibiting colon tumourigenesis. The novelty of this study is to use PPARγ as the target to inhibit DNA damage to prevent the occurrence of CAC.
Topics: Animals; Mice; PPAR gamma; Azoxymethane; Dextran Sulfate; Reactive Oxygen Species; Colitis; Inflammation; Carcinogenesis; Cell Transformation, Neoplastic; Mice, Inbred C57BL; Disease Models, Animal
PubMed: 37776619
DOI: 10.1016/j.phymed.2023.155116 -
Inflammopharmacology Feb 2024This review will discuss evidence that aspirin possesses anticancer activity. Long-term observational retrospective studies on nurses and health professionals... (Review)
Review
This review will discuss evidence that aspirin possesses anticancer activity. Long-term observational retrospective studies on nurses and health professionals demonstrated that regular aspirin users had a significantly lower incidence of colorectal cancer (RCT). Prospective studies on patients with a high risk of developing colorectal polyps/cancer confirmed that aspirin use significantly lowered colorectal dysplasia. Numerous observational studies focused on the use of aspirin in a broad range of cancers demonstrating a consistent 20-30% preventive effect on cancer incidence and mortality. Random Controlled Trials provided conflicting results on the benefit of aspirin in preventing CRC. Based on the age, weight/body size of the subjects for reasons still being explored. Studies on rats/mice further demonstrated that treatment of animals with aspirin where colon cancer was induced chemically or genetically (APCMin mice) reduced colonic dysplasia and polyp formation. Aspirin treatment was also effective at reducing the growth of cancer cells transplanted into normal/immunocompromised mice, suggesting that aspirin may be effective in treating different cancers. This possibility is also supported in clinical studies that aspirin use pre- and postcancer diagnosis significantly reduced the metastatic spread of cancer and increased patient survival. Lastly, the importance of the antiplatelet actions of aspirin in the drug's anticancer activity and specifically cancer metastatic spread is discussed and the current controversy related to the conflicting recommendations of the USPSTF over the past five years on the use of aspirin to prevent CRC.
Topics: Humans; Mice; Rats; Animals; Aspirin; Anti-Inflammatory Agents, Non-Steroidal; Retrospective Studies; Prospective Studies; Colorectal Neoplasms
PubMed: 38064111
DOI: 10.1007/s10787-023-01346-2 -
Cell Reports Aug 2023Cyclin-dependent kinase 4 (CDK4) and retinoblastoma protein (RB) are both important cell-cycle regulators that function in different scenarios. Here, we report that FERM...
Cyclin-dependent kinase 4 (CDK4) and retinoblastoma protein (RB) are both important cell-cycle regulators that function in different scenarios. Here, we report that FERM domain-containing 8 (FRMD8) inhibits CDK4 activation and stabilizes RB, thereby causing cell-cycle arrest and inhibiting colorectal cancer (CRC) cell growth. FRMD8 interacts separately with CDK7 and CDK4, and it disrupts the interaction of CDK7 with CDK4, subsequently inhibiting CDK4 activation. FRMD8 competes with MDM2 to bind RB and attenuates MDM2-mediated RB degradation. Frmd8 deficiency in mice accelerates azoxymethane/dextran-sodium-sulfate-induced colorectal adenoma formation. The FRMD8 promoter is hypermethylated, and low expression of FRMD8 predicts poor prognosis in CRC patients. Further, we identify an LKCHE-containing FRMD8 peptide that blocks MDM2 binding to RB and stabilizes RB. Combined application of the CDK4 inhibitor and FRMD8 peptide leads to marked suppression of CRC cell growth. Therefore, using an LKCHE-containing peptide to interfere with the MDM2-RB interaction may have therapeutic value in CDK4/6 inhibitor-resistant patients.
Topics: Animals; Mice; Colonic Neoplasms; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinases; Phosphorylation; Retinoblastoma Protein
PubMed: 37527040
DOI: 10.1016/j.celrep.2023.112886