bims-instec Biomed News
on Intestinal stem cells and chemoresistance in colon cancer and intestinal regeneration
Issue of 2023‒02‒12
24 papers selected by
Maria-Virginia Giolito
Free University of Brussels

  1. Nat Commun. 2023 Feb 10. 14(1): 746
      A substantial proportion of cancer patients do not benefit from platinum-based chemotherapy (CT) due to the emergence of drug resistance. Here, we apply elemental imaging to the mapping of CT biodistribution after therapy in residual colorectal cancer and achieve a comprehensive analysis of the genetic program induced by oxaliplatin-based CT in the tumor microenvironment. We show that oxaliplatin is largely retained by cancer-associated fibroblasts (CAFs) long time after the treatment ceased. We determine that CT accumulation in CAFs intensifies TGF-beta activity, leading to the production of multiple factors enhancing cancer aggressiveness. We establish periostin as a stromal marker of chemotherapeutic activity intrinsically upregulated in consensus molecular subtype 4 (CMS4) tumors and highly expressed before and/or after treatment in patients unresponsive to therapy. Collectively, our study underscores the ability of CT-retaining CAFs to support cancer progression and resistance to treatment.
  2. Nucleic Acids Res. 2023 Feb 06. pii: gkad042. [Epub ahead of print]
      The intestinal epithelial regeneration is driven by intestinal stem cells under homeostatic conditions. Differentiated intestinal epithelial cells, such as Paneth cells, are capable of acquiring multipotency and contributing to regeneration upon the loss of intestinal stem cells. Paneth cells also support intestinal stem cell survival and regeneration. We report here that depletion of an RNA-binding protein named polypyrimidine tract binding protein 1 (PTBP1) in mouse intestinal epithelial cells causes intestinal stem cell death and epithelial regeneration failure. Mechanistically, we show that PTBP1 inhibits neuronal-like splicing programs in intestinal crypt cells, which is critical for maintaining intestinal stem cell stemness. This function is achieved at least in part through promoting the non-productive splicing of its paralog PTBP2. Moreover, PTBP1 inhibits the expression of an AKT inhibitor PHLDA3 in Paneth cells and permits AKT activation, which presumably maintains Paneth cell plasticity and function in supporting intestinal stem cell niche. We show that PTBP1 directly binds to a CU-rich region in the 3' UTR of Phlda3, which we demonstrate to be critical for downregulating the mRNA and protein levels of Phlda3. Our results thus reveal the multifaceted in vivo regulation of intestinal epithelial regeneration by PTBP1 at the post-transcriptional level.
  3. Int J Cancer. 2023 Feb 08.
      Immunotherapy, especially with immune checkpoint inhibitors (ICIs), has shown advantages in cancer treatment and is a new hope for patients who have failed multiline therapy. However, in colorectal cancer (CRC), the benefit is limited to a small subset of patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) metastatic CRC (mCRC). In addition, 45-60% of dMMR/MSI-H mCRC patients showed primary or acquired resistance to ICIs. This means that these patients may have potential unknown pathways mediating immune escape. Almost all mismatch repair-proficient (pMMR) or microsatellite-stable (MSS) mCRC patients do not benefit from ICIs. In this review, we discuss the mechanisms of action of ICIs and their current status in CRC. We then discuss the mechanisms of primary and acquired resistance to ICIs in CRC. Finally, we discuss promising therapeutic strategies to overcome resistance to ICIs in the clinic.
    Keywords:  colorectal cancer; drug resistance; immune checkpoint inhibitors; mechanism; treatment
  4. Cancers (Basel). 2023 Jan 28. pii: 805. [Epub ahead of print]15(3):
      Colorectal cancer is an important cause of morbidity and mortality worldwide. The current treatment landscape includes chemotherapy, targeted therapy, immunotherapy, radiotherapy, and surgery. A key challenge to improving patient outcomes is the significant inter-patient heterogeneity in treatment response. Tumour organoids derived from the patients' tumours via surgically resected or endoscopically biopsied tissue, have emerged as promising models for personalised medicine. This review synthesises the findings, to date, of studies which have explored the efficacy of ex vivo organoid sensitivity testing for predicting treatment response. Most studies have focused on predicting the response to standard-of-care radiotherapy and chemotherapy options. There is strong evidence to support organoid sensitivity testing of ionising radiation, 5-fluorouracil, and irinotecan, and to a lesser extent, oxaliplatin and TAS-102. Fewer studies have used organoids to identify patients who are likely to benefit from novel treatment options that otherwise remain in clinical trials. This review also summarises recent advancements in organoid culture to include non-epithelial components of the tumour microenvironment, to allow testing of immunotherapy and certain targeted therapy options. Overall, further prospective trials will support the implementation of organoid-based personalised medicine for colorectal cancer patients in the future.
    Keywords:  colorectal cancer; organoids; personalised medicine
  5. Cancers (Basel). 2023 Feb 03. pii: 973. [Epub ahead of print]15(3):
      Reactive oxygen species (ROS) are considered to be the main drivers of inflammatory bowel disease. We investigated whether this permanent insult compels intestinal stem cells to develop strategies to dampen the deleterious effects of ROS. As an adverse effect, this adaptation process may increase their tolerance to oncogenic insults and facilitate their neoplastic transformation. We submitted immortalized human colonic epithelial cells to either a mimic of chronic inflammation or to a chemical peroxide, analyzed how they adapted to stress, and addressed the biological relevance of these observations in databases. We demonstrated that cells adapt to chronic-inflammation-associated oxidative stress in vitro through a partial genetic reprogramming. Through a gene set enrichment analysis, we showed that this program is recurrently active in the intestinal mucosae of Crohn's and ulcerative colitis disease patients and evolves alongside disease progression. Based on a previously reported characterization of intestinal stem and precursor cells using tracing experiments, we lastly confirmed the activation of the program in intestinal precursor cells during murine colorectal cancer development. This adaptive process is thus likely to play a role in the progression of Crohn's and ulcerative disease, and potentially in the initiation of colorectal cancer.
    Keywords:  ZEB transcription factors; adaptation to chronic-inflammation-associated oxidative stress; inflammatory bowel disease progression; intestinal cell reprogramming
  6. Cell Death Dis. 2023 Feb 07. 14(2): 89
      Ribosome biogenesis (RiBi) plays a pivotal role in carcinogenesis by regulating protein translation and stress response. Here, we find that RRP15, a nucleolar protein critical for RiBi and checkpoint control, is frequently upregulated in primary CRCs and higher RRP15 expression positively correlated with TNM stage (P < 0.0001) and poor survival of CRC patients (P = 0.0011). Functionally, silencing RRP15 induces ribosome stress, cell cycle arrest, and apoptosis, resulting in suppression of cell proliferation and metastasis. Overexpression of RRP15 promotes cell proliferation and metastasis. Mechanistically, ribosome stress induced by RRP15 deficiency facilitates translation of TOP mRNA LZTS2 (Leucine zipper tumor suppressor 2), leading to the nuclear export and degradation of β-catenin to suppress Wnt/β-catenin signaling in CRC. In conclusion, ribosome stress induced by RRP15 deficiency inhibits CRC cell proliferation and metastasis via suppressing the Wnt/β-catenin pathway, suggesting a potential new target in high-RiBi CRC patients.
  7. J Gastroenterol. 2023 Feb 05.
      BACKGROUND: Amino acid transporters play an important role in supplying nutrition to cells and are associated with cell proliferation. L-type amino acid transporter 1 (LAT1) is highly expressed in many types of cancers and promotes tumor growth; however, how LAT1 affects tumor development is not fully understood.METHODS: To investigate the role of LAT1 in intestinal tumorigenesis, mice carrying LAT1 floxed alleles that also expressed Cre recombinase from the promoter of gene encoding Villin were crossed to an ApcMin/+ background (LAT1fl/fl; vil-cre; ApcMin/+), which were subject to analysis; organoids derived from those mice were also analyzed.
    RESULTS: This study showed that LAT1 was constitutively expressed in normal crypt base cells, and its conditional deletion in the intestinal epithelium resulted in fewer Paneth cells. LAT1 deletion reduced tumor size and number in the small intestine of ApcMin/+ mice. Organoids derived from LAT1-deleted ApcMin/+ intestinal crypts displayed fewer spherical organoids with reduced Wnt/β-catenin target gene expression, suggesting a low tumor-initiation capacity. Wnt3 expression was decreased in the absence of LAT1 in the intestinal epithelium, suggesting that loss of Paneth cells due to LAT1 deficiency reduced the risk of tumor initiation by decreasing Wnt3 production.
    CONCLUSIONS: LAT1 affects intestinal tumor development in a cell-extrinsic manner through reduced Wnt3 expression in Paneth cells. Our findings may partly explain how nutrient availability can affect the risk of tumor development in the intestines.
    Keywords:  Cancer; L-type amino acid transporter 1; Paneth cells; Wnt3; mTORC1
  8. Carcinogenesis. 2023 Feb 08. pii: bgad005. [Epub ahead of print]
      Chronic inflammation is widely recognized as a major risk factor for cancer formation, but the underlying mechanisms are poorly understood. Recently, it was shown that Gasdermin D (GSDMD) protein drives pyroptotic cell death in macrophages upon cleavage by inflammatory caspases. Even though the Gsdmd gene is specifically expressed in the intestinal epithelium, the role of Gsdmd in the intestinal tissues remains poorly characterized. In this study, we examined the biological role of Gsdmd in colorectal cancer (CRC) development, employing an azoxymethane (AOM)/dextran sulfate sodium (DSS) carcinogenesis model. Results show that Gsdmd deficiency enhances CRC development, probably due to decreased apoptosis caused by down-regulation of interferon-gamma (IFNγ) - signal transducer and activator 1 (STAT1) signaling. Furthermore, we show that GSDMD protein is diminished in human colorectal cancer, indicating involvement of GSDMD in repression of CRC development in humans. Our findings provide a new insight into functions of Gsdmd/GSDMD in colonic inflammation and human CRC development.
    Keywords:  Gasdermin D; colon cancer; pyroptosis
  9. Cancers (Basel). 2023 Feb 01. pii: 914. [Epub ahead of print]15(3):
      Immune checkpoint (IC) molecules act as receptors, expressed on immune effector cells, that are able to recognize specific ligands in normal or tumor cells [...].
  10. J Transl Med. 2023 Feb 04. 21(1): 82
      BACKGROUND: Our previous study showed that fucosyltransferase 2 (Fut2) deficiency is closely related to colitis. Colitis increases the risk for the development of colorectal cancer (CRC). This study aimed to investigate the effect and underlying mechanism of action of Fut2 in CRC.METHODS: Intestinal epithelium-specific Fut2 knockout (Fut2△IEC) mice were used in this study. CRC was induced using azoxymethane (AOM) and dextran sulfate sodium (DSS). Immunofluorescence was used to examine the fucosylation levels. Proteomics and N-glycoproteomics analyses, Ulex Europaeus Agglutinin I (UEA-I) affinity chromatography, immunoprecipitation, and rescue assay were used to investigate the mechanism of Fut2 in CRC.
    RESULTS: The expression of Fut2 and α-1,2-fucosylation was lower in colorectal tumor tissues than in the adjacent normal tissues of AOM/DSS-induced CRC mice. More colorectal tumors were detected in Fut2△IEC mice than in control mice, and significant downregulation of melanoma cell adhesion molecule (MCAM) fucosylation was detected in the colorectal tumor tissues of Fut2△IEC mice. Overexpression of Fut2 inhibited cell proliferation, invasion and tumor metastasis in vivo and in vitro in SW480 and HCT116 cells. Moreover, fucosylation of MCAM may be a mediator of Fut2 in CRC. Peracetylated 2-F-Fuc, a fucosyltransferase inhibitor, repressed fucosylation modification of MCAM and reversed the inhibitory effects of Fut2 overexpression on SW480 cell proliferation, migration, and invasion. Our results indicate that Fut2 deficiency in the intestinal epithelium promotes CRC by downregulating the fucosylation of MCAM.
    CONCLUSIONS: The regulation of fucosylation may be an potential therapy for CRC, especially in patients with Fut2 gene defects.
    Keywords:  CRC; Colorectal cancer; Fucosylation; Fut2; MCAM
  11. Cell Rep. 2023 Feb 10. pii: S2211-1247(23)00104-3. [Epub ahead of print]42(2): 112093
      Apical-basal polarity and cell-fate determinants are crucial for the cell fate and control of stem cell numbers. However, their interplay leading to a precise stem cell number remains unclear. Drosophila pupal intestinal stem cells (pISCs) asymmetrically divide, generating one apical ISC progenitor and one basal Prospero (Pros)+ enteroendocrine mother cell (EMC), followed by symmetric divisions of each daughter before adulthood, providing an ideal system to investigate the outcomes of polarity loss. Using lineage tracing and ex vivo live imaging, we identify an interlocked polarity regulation network precisely determining ISC number: Bazooka inhibits Pros accumulation by activating Notch signaling to maintain stem cell fate in pISC apical daughters. A threshold of Pros promotes differentiation to EMCs and avoids ISC-like cell fate, and over-threshold of Pros inhibits miranda expression to ensure symmetric divisions in pISC basal daughters. Our work suggests that a polarity-dependent threshold of a differentiation factor precisely controls stem cell number.
    Keywords:  Baz; CP: Cell biology; CP: Stem cell research; Mira; Notch activation; Par-6; Pros threshold; aPKC; apical-basal polarity; pupal intestinal stem cell; stem cell number
  12. Cell Death Dis. 2023 Feb 09. 14(2): 96
      Telomere maintenance is necessary to maintain cancer cell unlimited viability. However, the mechanisms maintaining telomere length in colorectal cancer (CRC) have not been extensively investigated. Telomere maintenance mechanisms (TMM) include the re-expression of telomerase or alternative lengthening of telomeres (ALT). ALT is genetically associated with somatic alterations in alpha-thalassemia/mental retardation X-linked (ATRX) and death domain-associated protein (DAXX) genes. Cells displaying ALT present distinctive features including C-circles made of telomeric DNA, long and heterogenous telomeric tracts, and telomeric DNA co-localized with promyelocytic leukemia (PML) bodies forming so-called ALT-associated PML bodies (APBs). Here, we identified mutations in ATRX and/or DAXX genes in an extensive collection of CRC samples including 119 patient-derived organoids (PDOs) and 232 established CRC cell lines. C-circles measured in CRC PDOs and cell lines showed low levels overall. We also observed that CRC PDOs and cell lines did not display a significant accumulation of APBs or long telomeres with no appreciable differences between wild-type and mutated ATRX/DAXX samples. Overall, our extensive analyses indicate that CRC is not prone to engage ALT, even when carrying genetic lesions in ATRX and/or DAXX, and support the notion that ATRX/DAXX genomic footprints are not reliable predictors of ALT.
  13. Cancers (Basel). 2023 Jan 30. pii: 863. [Epub ahead of print]15(3):
      Colorectal cancer (CRC) is the third most frequent cancer and the second most common cause of cancer-related death in Europe. High microsatellite instability (MSI-H) due to a deficient DNA mismatch repair (dMMR) system can be found in 5% of metastatic CRC (mCRC) and has been established as a biomarker of response to immunotherapy in these tumors. Therefore, immune checkpoint inhibitors (ICIs) in mCRC with these characteristics were evaluated with results showing remarkable response rates and durations of response. The majority of mCRC cases have high levels of DNA mismatch repair proteins (pMMR) with consequent microsatellite stability or low instability (MSS or MSI-low), associated with an inherent resistance to ICIs. This review aims to provide a comprehensive analysis of the possible approaches to overcome the mechanisms of resistance and evaluates potential biomarkers to establish the role of ICIs in pMMR/MSS/MSI-L (MSS) mCRC.
    Keywords:  MSS; POLE/POLD1; TMB; biomarkers; immune checkpoint inhibitors (ICI); immunoscore; metastatic colorectal carcinoma (mCRC); microbiome; pMMR
  14. Br J Cancer. 2023 Feb 09.
      BACKGROUND: Long-term prognosis remains poor for colorectal cancer (CRC) patients with advanced disease due to treatment resistance. The identification of novel targets is essential for the development of new therapeutic approaches. GPR56, an adhesion GPCR, is highly expressed in CRC tumours and correlates with poor survival. Here, we describe the generation and preclinical evaluation of a novel ADC consisting of an anti-GPR56 antibody (10C7) conjugated with the DNA-damaging payload duocarmycin.METHODS: RNA-seq dataset analysis was performed to determine GPR56 expression in CRC subtypes. The specificity of binding, epitope mapping, and internalisation of 10C7 was examined. 10C7 was conjugated to payload and ADC cytotoxicity was assessed against a panel of CRC cell lines and tumour organoids. Antitumour efficacy was evaluated in xenograft models of CRC cell lines and patient-derived tumours.
    RESULTS: High GPR56 was shown to be associated with the microsatellite stable (MSS) subtype that accounts for 80-85% of CRC. GPR56 ADC selectively induced cytotoxicity in CRC cells and tumour organoids at low nanomolar potency in a GPR56-dependent manner and showed significant antitumour efficacy against GPR56-expressing xenograft models.
    CONCLUSIONS: This study provides the rationale for the future development of a GPR56-targeted ADC approach to potentially treat a large fraction of MSS CRC patients.
  15. Cell Biosci. 2023 Feb 08. 13(1): 25
      With high prevalence and mortality, together with metabolic reprogramming, colorectal cancer is a leading cause of cancer-related death. Metabolic reprogramming gives tumors the capacity for long-term cell proliferation, making it a distinguishing feature of cancer. Energy and intermediate metabolites produced by metabolic reprogramming fuel the rapid growth of cancer cells. Aberrant metabolic enzyme-mediated tumor metabolism is regulated at multiple levels. Notably, tumor metabolism is affected by nutrient levels, cell interactions, and transcriptional and posttranscriptional regulation. Understanding the crosstalk between metabolic enzymes and colorectal carcinogenesis factors is particularly important to advance research for targeted cancer therapy strategies via the investigation into the aberrant regulation of metabolic pathways. Hence, the abnormal roles and regulation of metabolic enzymes in recent years are reviewed in this paper, which provides an overview of targeted inhibitors for targeting metabolic enzymes in colorectal cancer that have been identified through tumor research or clinical trials.
    Keywords:  Colorectal cancer; Metabolic enzymes; Metabolic reprogramming; Signal transduction; Targeted therapy
  16. J Clin Oncol. 2023 Feb 10. JCO2201693
      PURPOSE: The positive BEACON colorectal cancer (CRC) safety lead-in, evaluating encorafenib + cetuximab + binimetinib in previously treated patients with BRAFV600E-mutated metastatic CRC (mCRC), prompted the design of the phase II ANCHOR CRC study ( identifier: NCT03693170). ANCHOR CRC aimed to evaluate efficacy, safety, and quality of life with first-line encorafenib + binimetinib + cetuximab in BRAFV600E-mutated mCRC.METHODS: In this multicenter, open-label, single-arm study, patients with BRAFV600E-mutated mCRC received oral encorafenib 300 mg once daily and binimetinib 45 mg twice daily in 28-day cycles, plus intravenous cetuximab 400 mg/m2 once on Day 1 of Cycle 1, then 250 mg/m2 once weekly for the first seven cycles, and 500 mg/m2 once on Days 1 and 15 from Cycle 8 onward. The primary end point was locally assessed confirmed objective response rate (cORR), and secondary end points included centrally assessed cORR, progression-free survival, overall survival (OS), quality of life, and safety and tolerability.
    RESULTS: Among 95 patients, the locally assessed cORR was 47.4% (95% CI, 37.0 to 57.9) with all partial responses. Since the lower limit of the 95% CI exceeded 30%, the primary end point was met. With a median follow-up duration of 20.1 months, the median progression-free survival on the basis of local assessments was 5.8 months and the median OS was 18.3 months. Treatment was well tolerated, with no unexpected toxicities. Using Patient Global Impression of Changes, substantial improvement in symptoms was consistently reported in ≥ 30% of patients from Cycle 3 to Cycle 10.
    CONCLUSION: The ANCHOR CRC study showed that the scientifically driven combination of encorafenib + binimetinib + cetuximab was active in the first-line setting of BRAFV600E-mutated mCRC with a manageable safety profile. Further first-line evaluation is ongoing ( identifier: NCT04607421).
  17. Cancers (Basel). 2023 Jan 18. pii: 606. [Epub ahead of print]15(3):
      Evidence for the tumor-supporting capacities of cancer-associated fibroblasts (CAFs) has rapidly been accumulating. To uncover clinicopathological importance of periostin (POSTN) expression in colorectal cancer (CRC), the present study immunohistochemically examined its expression status. Furthermore, to reveal its mechanisms involved, molecular experiments were performed. In CRC tissues, 44% of the cases (119/269) exhibited POSTN expression in the CAFs. In contrast, CRC cells expressed POSTN at almost undetectable levels. Survival analyses identified that patients with POSTN-positive CRC had a significantly worse 5-year survival rate (63.2% vs. 81.2%; p = 0.011). Univariate analyses revealed that POSTN positivity was associated with peritoneal (p = 0.0031) and distant organ metastasis (p < 0.001). Furthermore, immunohistochemical analyses identified a significant association between POSTN and p53 complete loss status in CRC cells. Decorin and fibroblast activation protein expression in CAFs was also associated with POSTN. POSTN significantly enhanced the migration of both CRC cells and fibroblasts with FAK and AKT or STAT3 activation, and co-culture assays demonstrated the communication between CRC cells and fibroblasts, which enhanced STAT3 activation in fibroblasts. On the basis of our results, we speculated that stromal POSTN accelerated metastasis via stromal remodeling capacity and activated the migration of both tumor and stromal cells.
    Keywords:  cancer-associated fibroblasts (CAFs); colorectal cancer (CRC); immunohistochemistry; migration; periostin (POSTN)
  18. Front Mol Biosci. 2023 ;10 1102209
      Intestinal organoids recapitulate many features of the in vivo gastrointestinal tract and have revolutionized in vitro studies of intestinal function and disease. However, the restricted accessibility of the apical surface of the organoids facing the central lumen (apical-in) limits studies related to nutrient uptake and drug absorption and metabolism. Here, we demonstrate that pluripotent stem cell (PSC)-derived intestinal organoids with reversed epithelial polarity (apical-out) can successfully recapitulate tissue-specific functions. In particular, these apical-out organoids show strong epithelial barrier formation with all the major junctional complexes, nutrient transport and active lipid metabolism. Furthermore, the organoids express drug-metabolizing enzymes and relevant apical and basolateral transporters. The scalable and robust generation of functional, apical-out intestinal organoids lays the foundation for a completely new range of organoid-based high-throughput/high-content in vitro applications in the fields of nutrition, metabolism and drug discovery.
    Keywords:  barrier integrity; drug discovery; epithelial polarity; gastrointestinal model; intestinal organoids; nutrient uptake
  19. Cancers (Basel). 2023 Jan 25. pii: 735. [Epub ahead of print]15(3):
      Genetic abnormalities induce the DNA damage response (DDR), which enables DNA repair at cell cycle checkpoints. Although the DDR is thought to function in preventing the onset and progression of cancer, DDR-related proteins are also thought to contribute to tumorigenesis, tumor progression, and drug resistance by preventing irreparable genomic abnormalities from inducing cell death. In the present study, the combination of ataxia telangiectasia-mutated serine/threonine kinase (ATM) and checkpoint kinase 1 (Chk1) inhibition exhibited synergistic antitumor effects and induced synergistic lethality in colorectal cancer cells at a low dose. The ATM and Chk1 inhibitors synergistically promoted the activation of cyclin-dependent kinase 1 by decreasing the phosphorylation levels of T14 and Y15. Furthermore, the combined treatment increased the number of sub-G1-stage cells, phospho-histone H2A.X-positive cells, and TdT-mediated dUTP nick-end labeling-positive cells among colon cancer cells, suggesting that the therapy induces apoptosis. Finally, the combined treatment exhibited a robust antitumor activity in syngeneic tumor model mice. These findings should contribute to the development of new treatments for colorectal cancer that directly exploit the genomic instability of cancer cells.
    Keywords:  ATM; CDK1; Chk1; cancer therapies; cell cycle checkpoint; synthetic lethality
  20. Comb Chem High Throughput Screen. 2023 Feb 09.
      AIMS: The present study investigated the exact proportion, the extent of in vitro proliferation potential, and oxaliplatin chemoresistance of EpCAMhigh/CD44+ cancer stem cells in colorectal cancer. Its underlying mechanism was also explored.BACKGROUND: Colorectal cancer stem cells (CSC) play crucial roles in tumorigenicity and chemoresistance. Multiple studies have shown that JAK/STAT, NOTCH, and Wnt/-catenin pathways, associated with tumour recurrence and metastasis, contribute to the proliferation and maintenance of CSCs. CSCs become resistant to chemo-radiotherapies by improving DNA damage repair, changing cell cycle checkpoints, and scavenging reactive oxygen species, resulting in a bad patient prognosis.
    OBJECTIVE: This work was carried out to determine the precise fraction, the degree of in vitro proliferation capability, and the level of oxaliplatin chemoresistance exhibited by EpCAMhigh/CD44+ cancer stem cells in colorectal cancer. The research was also done to investigate its underlying process.
    METHODS: Fluorescence-activated cell sorting (FACS) was applied to isolate the EpCAMhigh/CD44+ populations from three human colorectal cancer cell lines (HCT116, HT29, and LoVo), and we quantified the average proportion of the EpCAMhigh/CD44+ cells in every cell lines. The comparison of their proliferation ability and the chemoresistance to oxaliplatin with the parental cells was estimated by CCK8 assay. The activated signaling pathway was tested by Western Blotting.
    RESULTS: EpCAMhigh/CD44+ subpopulation comprises about 4.98±1.24% of the total human colorectal cancer cell lines, and the EpCAMhigh/CD44+ cells exhibited a highly better proliferation ability and stronger oxaliplatin chemoresistance than the parental cells. The wnt/β-catenin signaling pathway is activated in EpCAMhigh/CD44+ HCT116 cells.
    CONCLUSION: Activation of Wnt/β-Catenin signaling in EpCAMhigh/CD44+ cells endow colorectal cancer with tumor proliferation and oxaliplatin chemoresistance.
    Keywords:  CD44; Colorectal cancer; EpCAM; Oxaliplatin chemoresistance; Tumor proliferation; Wnt/β-Catenin signaling
  21. Nat Cancer. 2023 Feb 09.
      BRAFV600E mutation confers a poor prognosis in metastatic colorectal cancer (CRC) despite combinatorial targeted therapies based on the latest understanding of signaling circuitry. To identify parallel resistance mechanisms induced by BRAF-MEK-EGFR co-targeting, we used a high-throughput kinase activity mapping platform. Here we show that SRC kinases are systematically activated in BRAFV600E CRC following targeted inhibition of BRAF ± EGFR and that coordinated targeting of SRC with BRAF ± EGFR increases treatment efficacy in vitro and in vivo. SRC drives resistance to BRAF ± EGFR targeted therapy independently of ERK signaling by inducing transcriptional reprogramming through β-catenin (CTNNB1). The EGFR-independent compensatory activation of SRC kinases is mediated by an autocrine prostaglandin E2 loop that can be blocked with cyclooxygenase-2 (COX2) inhibitors. Co-targeting of COX2 with BRAF + EGFR promotes durable suppression of tumor growth in patient-derived tumor xenograft models. COX2 inhibition represents a drug-repurposing strategy to overcome therapeutic resistance in BRAFV600E CRC.
  22. Front Immunol. 2023 ;14 1105244
      Colorectal cancer (CRC) remains one of the most aggressive and lethal cancers, with metastasis accounting for most deaths. As such, there is an unmet need for improved therapies for metastatic CRC (mCRC). Currently, the research focus is shifting towards the reciprocal interactions within the tumor microenvironment (TME), which prevent tumor clearance by the immune system. Dendritic cells (DCs) play a key role in the initiation and amplification of anti-tumor immune responses and in driving the clinical success of immunotherapies. Dissecting the interactions between DCs and CRC cells may open doors to identifying key mediators in tumor progression, and possible therapeutic targets. This requires representative, robust and versatile models and tools. Currently, there is a shortage of such in vitro systems to model the CRC TME and its tumor-immune cell interactions. Here we develop and establish a dynamic organotypic 3D co-culture system to recapitulate and untangle the interactions between DCs and patient-derived mCRC tumor organoids. To our knowledge, this is the first study investigating human DCs in co-culture with tumor organoids in a 3D, organotypic setting. This system reveals how mCRC organoids modulate and shape monocyte-derived DCs (MoDCs) behavior, phenotype, and function, within a collagen matrix, using techniques such as brightfield and fluorescence microscopy, flow cytometry, and fluorescence-activated cell sorting. Our 3D co-culture model shows high viability and extensive interaction between DCs and tumor organoids, and its structure resembles patient tissue sections. Furthermore, it is possible to retrieve DCs from the co-cultures and characterize their phenotypic and functional profile. In our study, the expression of activation markers in both mature and immature DCs and their ability to activate T cells were impacted by co-culture with tumor organoids. In the future, this direct co-culture platform can be adapted and exploited to study the CRC-DC interplay in more detail, enabling novel and broader insights into CRC-driven DC (dys)function.
    Keywords:  3D co-culture; dendritic cell dysfunction; human dendritic cells; immunosuppression; metastatic colorectal cancer; patient-derived tumor organoids; tumor microenvironment
  23. Cells. 2023 Jan 31. pii: 459. [Epub ahead of print]12(3):
      Mast cells are tissue-resident sentinels involved in large number of physiological and pathological processes, such as infection and allergic response, thanks to the expression of a wide array of receptors. Mast cells are also frequently observed in a tumor microenvironment, suggesting their contribution in the transition from chronic inflammation to cancer. In particular, the link between inflammation and colorectal cancer development is becoming increasingly clear. It has long been recognized that patients with inflammatory bowel disease have an increased risk of developing colon cancer. Evidence from experimental animals also implicates the innate immune system in the development of sporadically occurring intestinal adenomas, the precursors to colorectal cancer. However, the exact role of mast cells in tumor initiation and growth remains controversial: mast cell-derived mediators can either exert pro-tumorigenic functions, causing the progression and spread of the tumor, or anti-tumorigenic functions, limiting the tumor's growth. Here, we review the multifaceted and often contrasting findings regarding the role of the intestinal mast cells in colon cancer progression focusing on the molecular pathways mainly involved in the regulation of mast cell plasticity/functions during tumor progression.
    Keywords:  colorectal cancer; mast cells; tumor microenvironment