BACKGROUND: The canonical Wnt signaling pathway controls the continuous renewal of the intestinal epithelium and the specification of epithelial cell lineages. Tcf4, a nuclear mediator of Wnt signaling, is essential for the differentiation and maintenance of Paneth cells in the small intestine. Its deficiency is associated with reduced expression of key α-defensins, highlighting its role in host-microbe interactions. However, the exact function of Tcf4 in specifying the secretory lineage and its contribution to antimicrobial peptide production remain incompletely understood. Remarkably, α-defensin expression has also been detected in human colon adenomas, where aberrant Wnt signaling is a hallmark. This raises important questions: What is the role of these Paneth-like cells in tumor biology, and how does Tcf4 influence their identity and function? METHODS: We investigated cell specification in small intestinal crypts and colon tumors using conditional Tcf7l2 deletion, cell type-specific Cre recombinases, and reporter alleles in mice. Transcriptomic (single-cell and bulk RNA sequencing) and histological analyses were performed and complemented by microbiome profiling, antibiotic treatment, and intestinal organoids to functionally validate the main findings. RESULTS: The inactivation of Tcf4 depletes Paneth cells and antimicrobial peptides, disrupting the gut microbiota balance. In secretory progenitors, loss of Tcf4 shifts differentiation toward goblet cells. In the small intestine, alternative secretory progenitors produce Wnt ligands to support stem cells and epithelial renewal in the absence of Paneth cells. In colon tumors, Paneth-like cells form a tumor cell population, express Wnt ligands, and require Tcf4 for their identity. Loss of Tcf4 redirects their differentiation toward goblet cells. CONCLUSIONS: Tcf4 controls the balance between Paneth and goblet cells and is essential for antimicrobial peptide production in the small intestine. In colon adenomas, Paneth-like tumor cells drive antimicrobial gene expression and provide Wnt3 ligands, which may have implications for cancer therapy.

• Klíčová slova
• Antimicrobial peptides, Colorectal cancer, Intestinal cell lineage, Intestinal crypt, Paneth cells, Single-cell transcriptomics,
• MeSH
• alfa-defensiny metabolismus   MeSH
• buněčná diferenciace MeSH
• lidé MeSH
• myši MeSH
• nádory tračníku * patologie   genetika   mikrobiologie   metabolismus   MeSH
• organoidy metabolismus   MeSH
• Panethovy buňky metabolismus   MeSH
• pohárkové buňky metabolismus   MeSH
• signální dráha Wnt MeSH
• střevní mikroflóra * MeSH
• tenké střevo * metabolismus   patologie   mikrobiologie   MeSH
• transkripční faktor 4 * metabolismus   genetika   MeSH
• transkriptom * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alfa-defensiny MeSH
• Tcf4 protein, mouse MeSH Prohlížeč
• transkripční faktor 4 * MeSH

Proto-oncogene KRAS, GTPase (KRAS) is one of the most intensively studied oncogenes in cancer research. Although several mouse models allow for regulated expression of mutant KRAS, selective isolation and analysis of transforming or tumor cells that produce the KRAS oncogene remains a challenge. In our study, we present a knock-in model of oncogenic variant KRASG12D that enables the "activation" of KRASG12D expression together with production of red fluorescent protein tdTomato. Both proteins are expressed from the endogenous Kras locus after recombination of a transcriptional stop box in the genomic DNA by the enzyme flippase (Flp). We have demonstrated the functionality of the allele termed RedRas (abbreviated KrasRR) under in vitro conditions with mouse embryonic fibroblasts and organoids and in vivo in the lung and colon epithelium. After recombination with adenoviral vectors carrying the Flp gene, the KrasRR allele itself triggers formation of lung adenomas. In the colon epithelium, it causes the progression of adenomas that are triggered by the loss of tumor suppressor adenomatous polyposis coli (APC). Importantly, cells in which recombination has successfully occurred can be visualized and isolated using the fluorescence emitted by tdTomato. Furthermore, we show that KRASG12D production enables intestinal organoid growth independent of epidermal growth factor (EGF) signaling and that the KRASG12D function is effectively suppressed by specific inhibitor MRTX1133.

• Klíčová slova
• Colon cancer, Gene targeting, Intestinal organoids, KRAS oncogene, Lung cancer, MRTX1133 inhibitor,
• MeSH
• červený fluorescenční protein * MeSH
• DNA-nukleotidyltransferasy genetika   metabolismus   MeSH
• genový knockin MeSH
• luminescentní proteiny * genetika   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• myši transgenní MeSH
• myši MeSH
• nádory plic genetika   patologie   MeSH
• protoonkogenní proteiny p21(ras) * genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• červený fluorescenční protein * MeSH
• DNA-nukleotidyltransferasy MeSH
• Hras protein, mouse MeSH Prohlížeč
• luminescentní proteiny * MeSH
• protoonkogenní proteiny p21(ras) * MeSH

The intestinal epithelium, a rapidly renewing tissue, is characterized by a continuous cell turnover that occurs through a well-coordinated process of cell proliferation and differentiation. This dynamic is crucial for the long-term function of the gastrointestinal tract. Disruption of this process can lead to colorectal carcinoma, a common malignancy worldwide. The first part of the review focuses on the cellular composition of the epithelium and the molecular mechanisms that control its functions, and describes the pathways that lead to epithelial transformation and tumor progression. This forms the basis for understanding the development and progression of advanced colorectal cancer. The second part deals with current therapeutic approaches and presents the latest treatment options, ongoing clinical trials and new drugs. In addition, the biological and medical perspectives of the adverse effects of therapies and models of regeneration of the intestinal epithelium are highlighted and, finally, future treatment options are discussed.

• Klíčová slova
• chemotherapy, colorectal cancer, immunotherapy, intestinal epithelium, regeneration, signaling pathways, targeted therapy,
• MeSH
• kolorektální nádory * terapie   patologie   MeSH
• lidé MeSH
• nádorová transformace buněk MeSH
• onkologové MeSH
• střevní sliznice patologie   účinky léků   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Trophoblastic cell surface antigen 2 (TROP2) is a membrane glycoprotein overexpressed in many solid tumors with a poor prognosis, including intestinal neoplasms. In our study, we show that TROP2 is expressed in preneoplastic lesions, and its expression is maintained in most colorectal cancers (CRC). High TROP2 positivity correlated with lymph node metastases and poor tumor differentiation and was a negative prognostic factor. To investigate the role of TROP2 in intestinal tumors, we analyzed two mouse models with conditional disruption of the adenomatous polyposis coli (Apc) tumor-suppressor gene, human adenocarcinoma samples, patient-derived organoids, and TROP2-deficient tumor cells. We found that Trop2 is produced early after Apc inactivation and its expression is associated with the transcription of genes involved in epithelial-mesenchymal transition, the regulation of migration, invasiveness, and extracellular matrix remodeling. A functionally similar group of genes was also enriched in TROP2-positive cells from human CRC samples. To decipher the driving mechanism of TROP2 expression, we analyzed its promoter. In human cells, this promoter was activated by β-catenin and additionally by the Yes1-associated transcriptional regulator (YAP). The regulation of TROP2 expression by active YAP was verified by YAP knockdown in CRC cells. Our results suggest a possible link between aberrantly activated Wnt/β-catenin signaling, YAP, and TROP2 expression.

• Klíčová slova
• APC, EMT, TACSTD2, WNT/β-catenin signaling, colorectal cancer, expression profiling, organoids,
• Publikační typ
• časopisecké články MeSH