bims-instec Biomed News
on Intestinal stem cells and chemoresistance in colon cancer and intestinal regeneration
Issue of 2023‒01‒01
six papers selected by
Maria-Virginia Giolito
Free University of Brussels

  1. Cell Mol Gastroenterol Hepatol. 2022 Dec 27. pii: S2352-345X(22)00263-6. [Epub ahead of print]
      BACKGROUND AND AIMS: The Intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis. An imbalance in this highly regimented process within the intestinal crypts is associated with several intestinal pathologies. Although metabolic changes are known to play a pivotal role in cell proliferation and differentiation, how glycolysis contributes to intestinal epithelial homeostasis remains to be defined.METHODS: Small intestines were harvested from mice with specific hexokinase 2 (HK2) deletion in the intestinal epithelium or LGR5+ stem cells. Glycolysis was measured using the Seahorse XFe96 analyzer. Expression of phospho-p38 MAPK, the transcription factor atonal homolog 1 (ATOH1), and intestinal cell differentiation markers lysozyme, mucin 2, and chromogranin A were determined by western blot, qPCR or IF and IHC staining.
    RESULTS: HK2 is a target gene of Wnt signaling in intestinal epithelium. HK2 knockout (KO) or inhibition of glycolysis resulted in increased numbers of Paneth, goblet, and enteroendocrine cells and decreased intestinal stem cell self-renewal. Mechanistically, HK2 KO resulted in activation of p38 MAPK and increased expression of ATOH1; inhibition of p38 MAPK signaling attenuated the phenotypes induced by HK2 KO in intestinal organoids. HK2 KO significantly decreased glycolysis and lactate production in intestinal organoids; supplementation of lactate or pyruvate reversed the phenotypes induced by HK2 KO.
    CONCLUSIONS: Our results show that HK2 regulates intestinal stem cell self-renewal and differentiation through p38 MAPK/ATOH1 signaling pathway. Our findings demonstrate an essential role for glycolysis in maintenance of intestinal stem cell function.
    Keywords:  HK2; glycolysis; intestinal stem cells; metabolism
  2. Cancer Cell. 2022 Dec 21. pii: S1535-6108(22)00589-X. [Epub ahead of print]
      Patients affected by colorectal cancer (CRC) with DNA mismatch repair deficiency (MMRd), often respond to immune checkpoint blockade therapies, while those with mismatch repair-proficient (MMRp) tumors generally do not. Interestingly, a subset of MMRp CRCs contains variable fractions of MMRd cells, but it is unknown how their presence impacts immune surveillance. We asked whether modulation of the MMRd fraction in MMR heterogeneous tumors acts as an endogenous cancer vaccine by promoting immune surveillance. To test this hypothesis, we use isogenic MMRp (Mlh1+/+) and MMRd (Mlh1-/-) mouse CRC cells. MMRp/MMRd cells mixed at different ratios are injected in immunocompetent mice and tumor rejection is observed when at least 50% of cells are MMRd. To enrich the MMRd fraction, MMRp/MMRd tumors are treated with 6-thioguanine, which leads to tumor rejection. These results suggest that genetic and pharmacological modulation of the DNA mismatch repair machinery potentiate the immunogenicity of MMR heterogeneous tumors.
    Keywords:  6-thioguanine; heterogeneity; immune checkpoint blockade; immune evasion; immune surveillance; microsatellite unstable tumors (MSI); mismatch repair; temozolomide
  3. EMBO Mol Med. 2022 Dec 27. e16427
      Paneth cells are versatile secretory cells located in the crypts of Lieberkühn of the small intestine. In normal conditions, they function as the cornerstones of intestinal health by preserving homeostasis. They perform this function by providing niche factors to the intestinal stem cell compartment, regulating the composition of the microbiome through the production and secretion of antimicrobial peptides, performing phagocytosis and efferocytosis, taking up heavy metals, and preserving barrier integrity. Disturbances in one or more of these functions can lead to intestinal as well as systemic inflammatory and infectious diseases. This review discusses the multiple functions of Paneth cells, and the mechanisms and consequences of Paneth cell dysfunction. It also provides an overview of the tools available for studying Paneth cells.
    Keywords:  antimicrobial peptides; gut homeostasis; infection; paneth cells
  4. J Gastrointest Cancer. 2022 Dec 31.
      PURPOSE: Colorectal cancer (CRC) appears to arise from sequential genetic lesions in tumor suppressor genes (APC, SMAD4, and TP53) and oncogenes (KRAS) leading to the classical adenoma to carcinoma progression. Biallelic APC inactivating genetic aberrations are detected in about 70% of early microadenomas implicating APC inactivation as the first genetic hit in CRC. APC is an essential protein of the Wnt 'destruction complex'; APC inactivation is believed to cause disruption of the complex allowing stabilization and nuclear translocation of β-catenin, resulting in transcriptional activation of cancer-promoting genes.METHODS: β-catenin nuclear localization and APC mutation were validated from serial FFPE sections representing the same tumor regions, using immunohistochemistry and Sanger sequencing, respectively.
    RESULTS: Here, we provide evidence for a surprising lack of correlation between APC mutation and β-catenin nuclear localization in early-onset sporadic rectal cancer samples. Several factors including status of KRAS mutation could not explain this anomaly. The lack of correlation was validated in CRC cell lines harboring various APC mutations.
    CONCLUSION: Our results provide evidence directly from tumor samples for possible non-canonical role(s) for mutant APC.
    Keywords:  APC; CRC; Wnt signaling; β-catenin
  5. Dig Dis Sci. 2022 Dec 28.
      Colorectal cancer (CRC) is one of the most frequent gastrointestinal malignant tumors worldwide. Immune checkpoint therapies (ICTs) have been proven to be a reliable treatment for some subtypes of CRC. Gut microbiome is closely involved in intestinal carcinogenesis through the regulation of local immune and inflammation of colonic mucosa. Numerous studies have demonstrated that the immunotherapeutic efficacy of CRC and other kinds of cancer is influenced by the immunosuppressive microenvironment constituted by intestinal microbiome and their metabolites. This Review will discuss the recent advances in how gut microbiome can modify the immune microenvironment and its potential role in ICTs of CRC.
    Keywords:  Colorectal cancer; Gut microbiome; Immune checkpoint therapy; Immune regulation
  6. Pharmacol Res. 2022 Dec 24. pii: S1043-6618(22)00579-5. [Epub ahead of print] 106633
      The changes in gut microbiota have been implicated in colorectal cancer (CRC). The interplays between the host and gut microbiota remain largely unclear, and few studies have investigated these interplays using integrative multi-omics data. In this study, large-scale multi-comic datasets, including microbiome, metabolome, bulk transcriptomics and single cell RNA sequencing of CRC patients, were analyzed individually and integrated through advanced bioinformatics methods. We further examined the clinical relevance of these findings in the mice recolonized with microbiota from human. We found that CRC patients had distinct microbiota compositions compared to healthy controls. A machine-learning model was developed with 28 biomarkers for detection of CRC, which had high accuracy and clinical applicability. We identified multiple significant correlations between genera and well-characterized genes, suggesting the potential role of gut microbiota in tumor immunity. Further analysis showed that specific metabolites worked as profound communicators between these genera and tumor immunity. Integrating microbiota and metabolome perspectives, we catalogued gut taxonomic and metabolomic features that represented the key multi-omics signature of CRC. Furthermore, gut microbiota from CRC patients transplanted to compromise the response of CRC to immunotherapy. These phenotypes were strongly associated with the alterations in gut microbiota, immune cell infiltration as well as multiple metabolic pathways. The comprehensive interplays across multi-comic data of CRC might explain how gut microbiota influenced tumor immunity. Hence, we proposed that modifying the CRC microbiota using healthy donors might serve as a promising strategy to improve response to immunotherapy.
    Keywords:  Colorectal cancer; fecal microbiota transplantation; gut microbiota; immunotherapy; multi-omics approach