bims-instec Biomed News
on Intestinal stem cells and chemoresistance in colon cancer and intestinal regeneration
Issue of 2021‒07‒25
five papers selected by
Maria-Virginia Giolito

  1. Hum Mol Genet. 2021 Jul 19. pii: ddab206. [Epub ahead of print]
      Many hereditary cancer syndromes are associated with an increased risk of small and large intestinal adenocarcinomas. However, conditions bearing a high risk to both adenocarcinomas and neuroendocrine tumors are yet to be described. We studied a family with 16 individuals in four generations affected by a wide spectrum of intestinal tumors, including hyperplastic polyps, adenomas, small intestinal neuroendocrine tumors, and colorectal and small intestinal adenocarcinomas. To assess the genetic susceptibility and understand the novel phenotype we utilized multiple molecular methods, including whole genome sequencing, RNA sequencing, single cell sequencing, RNA in situ hybridization, and organoid culture. We detected a heterozygous deletion at the cystic fibrosis locus (7q31.2) perfectly segregating with the intestinal tumor predisposition in the family. The deletion removes a topologically associating domain (TAD) border between CFTR and WNT2, aberrantly activating WNT2 in the intestinal epithelium. These consequences suggest that the deletion predisposes to small intestinal neuroendocrine tumors and small and large intestinal adenocarcinomas, and reveals the broad tumorigenic effects of aberrant WNT activation in the human intestine.
  2. Mol Oncol. 2021 Jul 20.
      Distant metastasis is, unfortunately, the leading cause of death in colorectal cancer (CRC). Approximately 50% of CRC patients develop liver metastases, while 10-30% of patients develop pulmonary metastases. The occurrence of metastasis is considered to be almost exclusively driven by cancer stem cells (CSCs) formation. However, the key molecules that confer the transformation to stem cells in CRC, and subsequent metastasis, remain unclear. Far upstream element-binding protein 1 (FUBP1), a transcriptional regulator of c-Myc, was screened in CSCs of CRC by mass spectrometry and was examined by immunohistochemistry in a cohort of CRC tissues. FUBP1 was upregulated in 85% of KRAS-mutant and 25% of wild-type CRC patients. Further, whether in KRAS-mutant or wild-type patients, elevated FUBP1 was positively correlated with CRC lymph node metastasis and clinical stage, and negatively associated with overall survival. Overexpression of FUBP1 significantly enhanced CRC cell migration, invasion, tumor sphere formation, and CD133 and ALDH1 expression in vitro, and tumorigenicity in vivo. Mechanistically, FUBP1 promoted the initiation of CSCs by activating Wnt/β-catenin signaling via directly binding to the promoter of DVL1, a potent activator of β-catenin. Knockdown of DVL1 significantly inhibited the transformation to stem cells in, as well as the tumorigenicity of, CRC. Activation of Wnt/β-catenin signaling by DVL1 increased pluripotent transcription factors, including c-Myc, NANOG, SOX2. Moreover, FUBP1 was upregulated at the post-transcriptional level. Elevated FUBP1 levels in KRAS wild-type CRC patients is due to the decrease of Smurf2, which promotes ubiquitin-mediated degradation of FUBP1. In contrast, FUBP1 was upregulated in KRAS-mutant patients through both inhibition of caspase-3-dependent cleavage and decreased Smurf2. Our results demonstrate, for the first time, that FUBP1 is an oncogene, initiating the development of CSCs, as well as a new powerful endogenous Wnt-signaling agonist that could provide an important prognostic factor and therapeutic target for metastasis in both KRAS-mutant and wild-type CRC.
    Keywords:  Cancer stem cells; Colorectal cancer; FUBP1
  3. Front Oncol. 2021 ;11 645732
      There are only a few experimental studies which have investigated effects of glucose alone, and glucose in combination with insulin/insulin-like growth factors (IGF) on the growth of colon cancer. In the present study, we studied in vitro in human colorectal cancer cells originating from four Dukes' stages of colorectal cancer the effects of glucose, insulin and IGFs on proliferation, migration, cell cycle progression and gene expression of the IGF system. Growth of colon cancer cells originating from a Dukes' stage A was glucose-dependent, whereas growth of cancer cells from Dukes' stage B, C and D was glucose-independent. Stimulatory effects of insulin and IGFs on cell growth were observed only in colon cancer cells originating from Dukes' stage C and D. IGF-II stimulated migration in Dukes' stage B cells only. The growth stimulatory effects in Dukes' stage C and D colorectal cancer cells were accompanied by G2/M arrest and associated with an increased IGF-IR/IGF-II receptor ratio. In conclusion, our in vitro data suggest that the stimulating effects of glucose, IGFs and insulin on proliferation differ between colorectal cancer cells from early and late Dukes' stages. Stimulatory effects of glucose on proliferation appear predominantly present in stage Dukes' stage A colorectal cancer cells, while in contrast growth factor-mediated stimulation of cell proliferation is more pronounced in Dukes' late stage (metastasized) colorectal cancer cells. Moreover, our study suggests that a stringent glucose control may be important to control tumor growth in early stages of colorectal cancer, while inhibition of the endocrine actions of the IGFs and insulin become more important in the late (metastasized) stages of colorectal cancer to restrain growth of colon cancer cells.
    Keywords:  IGF-IR; IR; colorectal cancer; glucose; insulin; insulin-like growth factors
  4. Int J Biol Macromol. 2021 Jul 19. pii: S0141-8130(21)01557-9. [Epub ahead of print]
      The critical roles of transcription factors in cell differentiation and the delineation of cell phenotypes have been reported. The current study aimed to characterize the functions of the basic transcription factor 3 (BTF3) gene and its regulation of the intestinal stem cell marker B cell-specific Moloney murine leukemia virus insertion site 1 (BMI1) gene in colorectal cancer (CRC). Stem cell-like traits and epithelial-mesenchymal transition (EMT) of cultured human CRC cell line HCT116 were evaluated by CD133+ subpopulation counting, colony formation, tumorosphere generation, and expression of EMT-specific markers and stem cell markers. The interaction of BTF3 with BMI1 was analyzed. BTF3 was overexpressed in CRC tissues, which was associated with poor patient survival. BTF3 knockdown impaired the retention of stem cell-like traits of HCT116 and inhibited the EMT of HCT116 cells. BMI1 expression changed in a BTF3-dependent manner, and its overexpression could partially restore stem cell-like traits and EMT of cultured HCT116 cells after BTF3 knockdown. In parallel, treatment with the BMI1 inhibitor PTC-209 mimicked the effects of BTF3 knockdown on stem cell-like traits and EMT of cultured HCT116 cells. Together, these results support the notion that BTF3 and BMI1 are potential therapeutic targets to limit CRC metastasis.
    Keywords:  Colorectal cancer; Epithelial-to-mesenchymal transition; Stem cell-like trait
  5. J Transl Med. 2021 Jul 19. 19(1): 311
      BACKGROUND: Colorectal cancer (CRC) is a common malignant tumour of the digestive tract that is characterized by high patient morbidity and mortality rates. Claudin-7 (Cldn7), a tight junction protein, was recently reported to function as a candidate tumour suppressor gene in CRC. Our previous study demonstrated that the large intestine of C57/BL6 mice showed intestinal adenomas and abnormal Ki67 expression and distribution in the intestinal crypt when Cldn7 was knocked out. The aim of this study was to further investigate whether Cldn7 deficiency has non-tight junction functions, affects intestinal stemness properties, promotes CRC and to determine the specific mechanism.METHODS: Cell proliferation assays, migration assays, apoptosis assays, tumour sphere formation assays in vitro, and subcutaneous xenograft models in vivo were used to determine the effects of Cldn7 knockdown on the biological characteristics of CRC stem cells. Western blotting, qPCR and immunofluorescence staining were performed to identify the epithelial-mesenchymal transition and the activation of Wnt/β-catenin pathway in CRC stem cells. Cldn7 inducible conditional gene knockout mice and immunohistochemical staining further verified this hypothesis in vivo. The mechanism and target of Cldn7 were determined by performing a chromatin immunoprecipitation (ChIP) assay and coimmunoprecipitation (CoIP) assay.
    RESULTS: Cldn7 knock down in CRC stem cells promoted cell proliferation, migration, and globular growth in serum-free medium and the ability to form xenograft tumours; cell apoptosis was inhibited, while the cellular epithelial-mesenchymal transition was also observed. These changes in cell characteristics were achieved by activating the Wnt/β-catenin pathway and promoting the expression of downstream target genes after β-catenin entry into the nucleus, as observed in CRC cell lines and Cldn7 gene knockout mouse experiments. Using ChIP and CoIP experiments, we initially found that Cldn7 and Sox9 interacted at the protein level to activate the Wnt/β-catenin pathway.
    CONCLUSIONS: Based on our research, Cldn7 deficiency confers stemness properties in CRC through Sox9-mediated Wnt/β-catenin signalling. This result clarifies that Cldn7 plays an inhibitory role in CRC and reveals a possible molecular mechanism, which is conducive to further research on Cldn7 and cancer stem cells.
    Keywords:  Cancer stem cells; Claudin-7; Colorectal cancer; Epithelial–mesenchymal transition; Wnt/β-catenin