bims-instec Biomed News
on Intestinal stem cells and chemoresistance in colon cancer and intestinal regeneration
Issue of 2021‒10‒10
six papers selected by
Maria-Virginia Giolito

  1. Mol Cell Oncol. 2021 ;8(4): 1879614
      Oncogenic transformation of colorectal cancer cells is driven by a set of mutations that cause aberrant signaling of growth factor-receptor pathways. Using organoids, we demonstrate that the most frequent driver mutations in APC, KRAS, SMAD4, and TP53 are enhancers of the global mRNA translational capacity, which is linked to intestinal cell growth in an mTOR-dependent manner.
    Keywords:  Colorectal cancer; driver mutations; global translation; mTOR signaling; protein synthesis
  2. Cell Mol Gastroenterol Hepatol. 2021 Oct 01. pii: S2352-345X(21)00205-8. [Epub ahead of print]
      BACKGROUND & AIMS: Intestinal mucositis, a severe complication of antineoplastic therapeutics, is characterized by mucosal injury and inflammation in the small intestine. Therapies for prevention and treatment of this disease are needed. We investigated whether 2'-fucosyllactose (2'-FL), an abundant oligosaccharide in human milk, protects intestinal integrity and ameliorates intestinal mucositis.METHODS: A mouse small intestinal epithelial (MSIE) cell line, mouse enteroid cultures, and human gastrointestinal tumor cell lines (AGS and HT29) were co-treated with the chemotherapy agent 5-fluorouracil (5-FU) and 2'-FL. Mice were intraperitoneally injected with 5-FU to induce intestinal mucositis. 2'-FL was administered in the drinking water to mice before (pretreatment) or concurrently with 5-FU injection. Body weight and pathological changes were analyzed.
    RESULTS: 2'-FL alleviated 5-FU inhibition of cell growth in MSIE cells, but not in AGS and HT29 cells. The 5-FU-induced apoptosis in MSIE cells and enteroids was suppressed by 2'-FL. Compared with 5-FU treatment alone, 2'-FL pretreatment protected against body weight loss, and ameliorated inflammation scores, proinflammatory cytokine production, shortening of villi, epithelial cell apoptosis, goblet cell loss, and tight junctional complex disruption in the small intestine. 2'-FL concurrent treatment had less of effect on intestinal mucositis than 2'-FL pretreatment. Interestingly, no effect of 2'-FL was observed on 5-FU-induced S-phase arrest in MSIE, AGS and HT29 cells. Neither pretreatment nor concurrent treatment with 2'-FL affected 5-FU-induced inhibition of proliferation in small intestinal epithelial cells in mice.
    CONCLUSIONS: This study reveals a novel direct effect of 2'-FL in protecting small intestinal epithelial cells against apoptosis stimulated by 5-FU, which may contribute to prevention of 5-FU-induced intestinal mucositis.
    Keywords:  5-fluorouracil; human milk oligosaccharides; intestinal inflammation; proliferation
  3. Gastroenterology. 2021 Sep 29. pii: S0016-5085(21)03606-4. [Epub ahead of print]
      BACKGROUND AIMS: Throughout life, the intestinal epithelium undergoes constant self-renewal from intestinal stem cells. Together with genotoxic stressors and failing DNA repair, this self-renewal causes susceptibility towards malignant transformation. X-box binding protein 1 (XBP1) is a stress sensor involved in the unfolded protein response (UPR). We hypothesized that XBP1 acts as a signaling hub to regulate epithelial DNA damage responses.METHODS: Data from the TCGA were analyzed for association of XBP1 with CRC survival and molecular interactions between XBP1 andp53 pathway activity. The role of XBP1 in orchestrating p53-driven DNA damage response was tested in-vitro, in mouse models of chronic intestinal epithelial DNA damage (Xbp1/H2bfl/fl, Xbp1ΔIEC, H2bΔIEC, H2b/Xbp1ΔIEC) and via orthotopic tumor organoid transplantation. Transcriptome analysis of intestinal organoids was performed to identify molecular targets of Xbp1-mediated DNA damage response.
    RESULTS: In the TCGA dataset of CRC, low XBP1 expression was significantly associated with poor overall survival (OS) and reduced p53 pathway activity. In-vivo, H2b/Xbp1ΔIEC mice developed spontaneous intestinal carcinomas. Orthotopic tumor organoid transplantation revealed a metastatic potential of H2b/Xbp1ΔIEC-derived tumors. RNA sequencing of intestinal organoids (H2b/Xbp1fl/fl, H2bΔIEC, H2b/Xbp1ΔIEC, H2b/p53ΔIEC) identified a transcriptional program downstream of p53, in which XBP1 directs DNA damage-induced Ddit4l expression. DDIT4L inhibits mTOR-mediated phosphorylation of 4E-BP1. Pharmacological mTOR inhibition suppressed epithelial hyperproliferation via 4E-BP1.
    CONCLUSIONS: Our data suggest a crucial role for XBP1 in coordinating epithelial DNA damage responses and stem cell function via a p53-DDIT4L-dependent feedback mechanism.
    Keywords:  CRC; DNA damage; XBP1; intestinal epithelial cell; p53
  4. Oncogene. 2021 Oct 07.
      Cancer stem cells (CSCs) are responsible for tumor progression, recurrence, and drug resistance. To identify genetic vulnerabilities of colon cancer, we performed targeted CRISPR dropout screens comprising 657 Drugbank targets and 317 epigenetic regulators on two patient-derived colon CSC-enriched spheroids. Next-generation sequencing of pooled genomic DNAs isolated from surviving cells yielded therapeutic candidates. We unraveled 44 essential genes for colon CSC-enriched spheroids propagation, including key cholesterol biosynthetic genes (HMGCR, FDPS, and GGPS1). Cholesterol biosynthesis was induced in colon cancer tissues, especially CSC-enriched spheroids. The genetic and pharmacological inhibition of HMGCR/FDPS impaired self-renewal capacity and tumorigenic potential of the spheroid models in vitro and in vivo. Mechanistically, HMGCR or FDPS depletion impaired cancer stemness characteristics by activating TGF-β signaling, which in turn downregulated expression of inhibitors of differentiation (ID) proteins, key regulators of cancer stemness. Cholesterol and geranylgeranyl diphosphate (GGPP) rescued the growth inhibitory and signaling effect of HMGCR/FDPS blockade, implying a direct role of these metabolites in modulating stemness. Finally, cholesterol biosynthesis inhibitors and 5-FU demonstrated antitumor synergy in colon CSC-enriched spheroids, tumor organoids, and xenografts. Taken together, our study unravels novel genetic vulnerabilities of colon CSC-enriched spheroids and suggests cholesterol biosynthesis as a potential target in conjunction with traditional chemotherapy for colon cancer treatment.
  5. Oncotarget. 2021 Sep 28. 12(20): 2006-2021
      Colorectal cancer (CRC) caused over 900,000 deaths worldwide in 2020. A majority of late-stage CRC patients are treated with 5-fluorouracil (5-FU) combined with either irinotecan (CPT-11), oxaliplatin, or both. Despite their widespread use, the mechanisms of efficacy and toxicity of these drugs remain incompletely understood. While previous work has investigated cellular responses to these agents individually, we directly compare the transcriptomic and cytokine profiles of HCT116 wild-type and p53-/- colorectal cancer cells treated with these drugs and report pan-drug, drug-specific, drug class-specific, p53-independent, and p53-dependent signatures. We observed downregulation of histone genes by 5-FU (that significantly correlates with improved survival in CRC patients) and upregulation of FOS and ATF3 by oxaliplatin (which may contribute to peripheral neuropathy). BTG2 was identified as a top gene upregulated by all four drugs, suggesting its critical role in the cellular response to chemotherapy in CRC. Soluble TRAILR2 (death receptor 5; DR5) is a decoy receptor for TRAIL, an apoptosis-inducing cytokine. TRAILR2 was down-regulated by oxaliplatin and 5-FU, was not affected by CPT-11, and was increased by cisplatin. There was an increase in IL-8 by oxaliplatin and increase in ferritin by cisplatin which may contribute to cancer cell survival. Novel drug-specific mechanisms of efficacy or toxicity identified in these signatures may be targeted with combination therapies or development of new targeted therapies. Together, the findings here contribute to our understanding of the molecular bases of efficacy and toxicity of chemotherapeutic agents often used for treatment of GI cancer such as CRC.
    Keywords:  5-fluorouracil; chemotherapy mechanism; colon cancer; irinotecan; oxaliplatin
  6. Gastroenterology. 2021 Oct 01. pii: S0016-5085(21)03608-8. [Epub ahead of print]
      Chronic inflammation is a known risk factor for gastrointestinal cancer. The evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) suppress the incidence, growth, and metastasis of gastrointestinal cancer supports the concept that an NSAID target, cyclooxygenase (COX) and its downstream bioactive lipid products, may provide one of the links between inflammation and cancer. Preclinical studies have demonstrated that the COX-2-PGE2 pathway can promote gastrointestinal cancer development. Although the role of this pathway in cancer has been extensively investigated for two decades, only recent studies emerge describing its effects on host defenses against transformed epithelial cells. Overcoming tumor-immune evasion remains one of the major challenges in cancer immunotherapy. This review summarizes the impacts of the COX-PGE2 pathway on gastrointestinal cancer development. Our focus is to highlight recent advances in our understanding of how this pathway induces tumor immune evasion.