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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 -
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 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 -
JCI Insight Nov 2022Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD). HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) control cellular...
Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD). HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) control cellular adaptation to hypoxia and are considered promising therapeutic targets in IBD. However, their relevance in the pathogenesis of CAC remains elusive. We induced CAC in Phd1-/-, Phd2+/-, Phd3-/-, and WT mice with azoxymethane (AOM) and dextran sodium sulfate (DSS). Phd1-/- mice were protected against chronic colitis and displayed diminished CAC growth compared with WT mice. In Phd3-/- mice, colitis activity and CAC growth remained unaltered. In Phd2+/- mice, colitis activity was unaffected, but CAC growth was aggravated. Mechanistically, Phd2 deficiency (i) increased the number of tumor-associated macrophages in AOM/DSS-induced tumors, (ii) promoted the expression of EGFR ligand epiregulin in macrophages, and (iii) augmented the signal transducer and activator of transcription 3 and extracellular signal-regulated kinase 1/2 signaling, which at least in part contributed to aggravated tumor cell proliferation in colitis-associated tumors. Consistently, Phd2 deficiency in hematopoietic (Vav:Cre-Phd2fl/fl) but not in intestinal epithelial cells (Villin:Cre-Phd2fl/fl) increased CAC growth. In conclusion, the 3 different PHD isoenzymes have distinct and nonredundant effects, promoting (PHD1), diminishing (PHD2), or neutral (PHD3), on CAC growth.
Topics: Animals; Mice; Azoxymethane; Colitis; Colitis-Associated Neoplasms; Epithelial Cells; Prolyl Hydroxylases
PubMed: 36509284
DOI: 10.1172/jci.insight.153337 -
Journal of Biomedicine & Biotechnology 2011The dimethyhydrazine (DMH) or azoxymethane (AOM) model is a well-established, well-appreciated, and widely used model of experimental colon carcinogenesis. It has many... (Review)
Review
The dimethyhydrazine (DMH) or azoxymethane (AOM) model is a well-established, well-appreciated, and widely used model of experimental colon carcinogenesis. It has many morphological as well as molecular similarities to human sporadic colorectal cancer (CC), which are summarized and discussed in this paper. In addition, the paper combines present knowledge of morphological and molecular features in the multistep development of CC recognized in the DMH/AOM rat model. This understanding is necessary in order to accurately identify and interpret alterations that occur in the colonic mucosa when evaluating natural or pharmacological compounds in DMH/AOM rat colon carcinogenesis. The DMH/AOM model provides a wide range of options for investigating various initiating and environmental factors, the role of specific dietary and genetic factors, and therapeutic options in CC. The limitations of this model and suggested areas in which more research is required are also discussed.
Topics: 1,2-Dimethylhydrazine; Animals; Azoxymethane; Biomarkers, Tumor; Colonic Neoplasms; Humans; Precancerous Conditions; Rats; Terminology as Topic
PubMed: 21253581
DOI: 10.1155/2011/473964 -
Experimental Animals Nov 2020Colorectal cancer is the second most lethal cancer type across all ages and sexes, the many mechanisms of which are still currently being further elucidated. PIERCE1 has...
Colorectal cancer is the second most lethal cancer type across all ages and sexes, the many mechanisms of which are still currently being further elucidated. PIERCE1 has been known to be involved in the cell cycle and proliferation, the expression of which is regulated by stress conditions in a p53-dependent manner. Through a database search, we found that PIERCE1 was significantly augmented in patients with colorectal carcinoma compared to normal samples, suggesting its possible role in tumor regulation. Recently, PIERCE1 has also been reported to increase proliferation of a liver cancer cell line, indicating its possible role as an oncogene. To examine its relevance to tumorigenesis, such as whether it has either oncogenic or tumor suppressive function, PIERCE1 was knocked down and overexpressed in several colorectal cancer cell lines and mice, respectively. To evaluate the roles of Pierce1 in vivo, we established a Pierce1 transgenic (TG) mouse model and then administered azoxymethane with dextran sodium sulfate (DSS) to induce colorectal carcinogenesis via promoting mutations in Apc and Kras. Nonetheless, PIERCE1 depletion in these cell lines showed no significant change in cell growth. AOM/DSS-treated Pierce1 TG mice were comparable with respect to colon lengths, the number of polyps, and tumor sizes to those of the control mice. These results implicate that PIERCE1 does not play an oncogenic or tumor suppressive role in AOM/DSS-induced colorectal cancer.
Topics: Animals; Azoxymethane; Cell Cycle; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Dextran Sulfate; Disease Models, Animal; Female; Gene Expression; Humans; Male; Mice, Transgenic; Tumor Suppressor Protein p53
PubMed: 32581195
DOI: 10.1538/expanim.19-0155 -
Oncogene Nov 2021CCL11, also known as eotaxin-1, is described as an eosinophil chemoattractant, which has been implicated in allergic and Th2 inflammatory diseases. We have reported that...
CCL11, also known as eotaxin-1, is described as an eosinophil chemoattractant, which has been implicated in allergic and Th2 inflammatory diseases. We have reported that CCL11 is significantly increased in the serum of inflammatory bowel disease (IBD) patients, colonic eosinophils are increased and correlate with tissue CCL11 levels in ulcerative colitis patients, and CCL11 is increased in dextran sulfate sodium (DSS)-induced murine colitis. Here, we show that CCL11 is involved in the pathogenesis of DSS-induced colitis and in colon tumorigenesis in the azoxymethane (AOM)-DSS model of colitis-associated carcinogenesis (CAC). Ccl11 mice exposed to DSS then allowed to recover had significantly less body weight loss and a decrease in histologic injury versus wild-type (WT) mice. In the AOM-DSS model, Ccl11 mice exhibited decreased colonic tumor number and burden, histologic injury, and colonic eosinophil infiltration versus WT mice. Ccl11 is expressed by both colonic epithelial and lamina propria immune cells. Studies in bone marrow chimera mice revealed that hematopoietic- and epithelial-cell-derived CCL11 were both important for tumorigenesis in the AOM-DSS model. These findings indicate that CCL11 is important in the regulation of colitis and associated carcinogenesis and thus anti-CCL11 antibodies may be useful for treatment and cancer chemoprevention in IBD.
Topics: Animals; Azoxymethane; Carcinogenesis; Carcinogens; Chemokine CCL11; Colitis; Colitis-Associated Neoplasms; Epithelial Cells; Mice; Mice, Knockout
PubMed: 34625710
DOI: 10.1038/s41388-021-02046-3 -
Comparative Medicine Oct 2022Multiple animal models have been developed to investigate the pathogenesis of colorectal cancer and to evaluate potential treatments. One model system uses azoxymethane,...
Multiple animal models have been developed to investigate the pathogenesis of colorectal cancer and to evaluate potential treatments. One model system uses azoxymethane, a metabolite of cycasin, alone and in conjunction with dextran sodium sulfate to induce colon cancer in rodents. Azoxymethane is metabolized by hepatic P450 enzymes and can also be eliminated through the kidneys. In this study, C57BL/6J mice were fed either standard or high-fat diet and then all mice received azoxymethane at 10 mg/kg body weight twice a week for 6 wk. Shortly after the end of treatment, high mortality occurred in mice in the high-fat diet group. Postmortem examination revealed hepatic and renal pathology in mice on both diets. Histologic changes in liver included hepatocytomegaly with nuclear pleomorphism and bile duct hyperplasia accompanied by mixed inflammatory-cell infiltrates. Changes in the kidneys ranged from basophilia of tubular epithelium to tubular atrophy. The results indicate that further optimization of this model is needed when feeding a high-fat diet and giving multiple azoxymethane doses to induce colon cancer in C57BL/6J mice.
Topics: Mice; Animals; Azoxymethane; Diet, High-Fat; Mice, Inbred C57BL; Cycasin; Dextrans; Colonic Neoplasms; Liver; Kidney; Diet; Colon
PubMed: 36123012
DOI: 10.30802/AALAS-CM-22-000040 -
Frontiers in Immunology 2023(CB) is a spore-forming, gram-positive and obligate anaerobic rod bacterium. CB can modulate the composition of the gut microbiome and promote the growth of beneficial...
(CB) is a spore-forming, gram-positive and obligate anaerobic rod bacterium. CB can modulate the composition of the gut microbiome and promote the growth of beneficial microbes in the intestine by generating short-chain fatty acids (SCFAs), which in turn protect against colitis and prevents the formation of inflammatory-associated colorectal cancer (CRC) by ameliorating colon inflammatory processes. Yet, it remains unclear whether the culture and supernatant of CB could directly influence inflammatory CRC in mice. In this study, azoxymethane (AOM)+dextran sodium sulphate (DSS) was used to induce CRC model in C57BL/6 mice. Next, the serum levels of inflammatory cytokines, including interleukin-6 (IL-6), interleukin-10 (IL-10), and cytokines TNF-α, were measured and the pathohistological examination of the large intestine was performed. Both CB culture and supernatant were found to have anti-inflammatory properties. Subsequently, Western blot and Real-Time Quantitative PCR (RT-qPCR) revealed that CB and supernatant regulate the NF-κB/p65 pathway to inhibit the development and progression of inflammatory CRC in AOM+DSS-treated mice, which could be due to the high levels of butyric acid in the supernatant.
Topics: Animals; Mice; Colorectal Neoplasms; Clostridium butyricum; Mice, Inbred C57BL; Colitis; Cytokines; Azoxymethane
PubMed: 37081884
DOI: 10.3389/fimmu.2023.1004756 -
PeerJ 2023Colorectal cancer (CRC) is the third most common cancer. It is a heterogeneous disease, including both hereditary and sporadic types of tumors. CRC results from complex... (Review)
Review
BACKGROUND
Colorectal cancer (CRC) is the third most common cancer. It is a heterogeneous disease, including both hereditary and sporadic types of tumors. CRC results from complex interactions between various genetic and environmental factors. Inflammatory bowel disease is an important risk factor for developing CRC. Despite growing understanding of the CRC biology, preclinical models are still needed to investigate the etiology and pathogenesis of the disease, as well as to find new methods of treatment and prevention.
OBJECTIVES
The purpose of this review is to describe existing murine models of CRC with a focus on the models of colitis-associated CRC. This manuscript could be relevant for experimental biologists and oncologists.
METHODOLOGY
We checked PubMed and Google from 01/2018 to 05/2023 for reviews of CRC models. In addition, we searched PubMed from 01/2022 to 01/2023 for articles using the azoxymethane (AOM)/dextran sulfate sodium (DSS) CRC model.
RESULTS
Existing murine models of CRC include spontaneous, genetically engineered, transplantation, and chemically induced models. For the study of colitis-associated cancer (CAC), the AOM/DSS model is predominantly used. This model is very similar in histological and molecular characteristics to the human CAC, and is highly reproducible, inexpensive, and easy to use. Despite its popularity, the AOM/DSS model is not standardized, which makes it difficult to analyze and compare data from different studies.
CONCLUSIONS
Each model demonstrates particular advantages and disadvantages, and allows to reproduce different subtypes or aspects of the pathogenesis of CRC.
Topics: Mice; Humans; Animals; Azoxymethane; Dextran Sulfate; Colitis-Associated Neoplasms; Colitis; Disease Models, Animal; Colorectal Neoplasms
PubMed: 37927787
DOI: 10.7717/peerj.16159