Project description:We previously identified Dclk1, a tuft cell marker, marks tumor stem cells (TSCs) in mouse intestinal tumors. In this study, we have identified IL17RB as a cell surface marker distinctively expressed by Dclk1+ tuft-like tumor cells in mouse intestinal tumors. Using this tuft cell marker, we compared and analyzed the transcriptome of Lgr5-tuft marker-, Lgr5+tuft marker-, Lgr5-tuft marker+, and Lgr5+tuft marker+ tumor cells. These analyses revealed that tuft-like tumor cells in the intestinal tumors comprise two distinct subsets: highly differentiated tuft-like tumor cells (Lgr5-tuft marker+ cells) and tuft-like tumor cells with TCS potential (Lgr5+tuft marker+ cells).
Project description:The Wnt target gene Lgr5 marks actively dividing stem cells in Wnt-driven, self-renewing tissues such as small intestine and colon, stomach and hair follicles. A 3D culture system allows long-term clonal expansion of single Lgr5+ stem cells into transplantable organoids that retain many characteristics of the original epithelial architecture. A crucial component of the culture medium is the Wnt agonist Rspo, the recently discovered ligand of Lgr5. Here we show that Lgr5-LacZ is not expressed in healthy adult liver, yet that small Lgr5-LacZ+ cells appear near bile ducts upon damage, coinciding with robust activation of Wnt signaling. As shown by lineage tracing using a novel Lgr5-ires-CreERT2 knock-in allele, damage-induced Lgr5+ cells generate hepatocytes and bile ducts in vivo. Single Lgr5+ cells from damaged liver can be clonally expanded as organoids in Rspo1-based culture medium over multiple months. Such clonal organoids can be induced to differentiate in vitro and to generate functional hepatocytes upon transplantation into FAH-/- mice. These findings imply that previous findings on Lgr5+ stem cells in actively self-renewing tissues extend to damage-induced stem cells in a tissue with a low rate of spontaneous self-renewal. We first generated arrays from multiple wildtype tissues including muscle, white adipose tissues, brown adipose tissues, liver and pancreas. Then we generated arrays from liver derived cultures maintained in different conditions, and compared the expression profile with the corresponding parental tissues and other non-related tissues.
Project description:The Wnt target gene Lgr5 marks actively dividing stem cells in Wnt-driven, self-renewing tissues such as small intestine and colon, stomach and hair follicles. A 3D culture system allows long-term clonal expansion of single Lgr5+ stem cells into transplantable organoids that retain many characteristics of the original epithelial architecture. A crucial component of the culture medium is the Wnt agonist Rspo, the recently discovered ligand of Lgr5. Here we show that Lgr5-LacZ is not expressed in healthy adult liver, yet that small Lgr5-LacZ+ cells appear near bile ducts upon damage, coinciding with robust activation of Wnt signaling. As shown by lineage tracing using a novel Lgr5-ires-CreERT2 knock-in allele, damage-induced Lgr5+ cells generate hepatocytes and bile ducts in vivo. Single Lgr5+ cells from damaged liver can be clonally expanded as organoids in Rspo1-based culture medium over multiple months. Such clonal organoids can be induced to differentiate in vitro and to generate functional hepatocytes upon transplantation into FAH-/- mice. These findings imply that previous findings on Lgr5+ stem cells in actively self-renewing tissues extend to damage-induced stem cells in a tissue with a low rate of spontaneous self-renewal.
Project description:The intestinal epithelium is continuously regenerated by highly proliferative Lgr5+ intestinal stem cells (ISCs). The existence of a population of quiescent ISCs has been suggested yet its identity and features remain controversial. Here we describe that the expression of the RNA-binding protein Mex3a labels a subpopulation of Lgr5+ cells that divide less frequently and contribute to regenerate all intestinal lineages with slow kinetics. Single cell transcriptomic analysis revealed two classes of Lgr5-high cells, one of them defined by the Mex3a-expression program and by low levels of proliferation genes. Lineage tracing experiments show that large fraction of Mex3a+ cell population is continuously recalled into the rapidly dividing self-renewing ISC pool in homeostatic conditions. Chemotherapy and radiation target preferentially rapidly dividing Lgr5+ cells but spare the Mex3a-high/Lgr5+ population, which helps sustain the renewal of the intestinal epithelium during treatment.
Project description:The Toll-like receptor 4 (TLR4) pathway is important for tumor-initiating cells. We used microarrays to obtain gene profiling data in order to increase understanding of the pathways. Liver tumor-initiating cells were used for RNA extraction and hybridization on Affymetrix microarrays.
Project description:We analyzed gene expression of 3 lines LGR5-GFP, 2 lines KRT20-GFP knock-in colorectal tumor organdies. The cancer stem cell (CSC) theory highlights a self-renewing subpopulation of cancer cells that fuels tumour growth. The existence of human CSCs is mainly supported by xenotransplantation of prospectively isolated cells, but their clonal dynamics and plasticity remain unclear. Here, we show that human LGR5+ colorectal cancer cells serve as CSCs in growing cancer tissues. Lineage-tracing experiments with a tamoxifen inducible Cre knock-in allele of LGR5 reveal the self-renewal and differentiation capacity of LGR5+ tumour cells. Selective ablation of LGR5+ CSCs in LGR5-iCaspase9 knock-in organoids leads to tumour regression, followed by tumour regrowth driven by re-emerging LGR5+ CSCs. KRT20 knock-in reporter marks differentiated cancer cells that constantly diminish in tumour tissues, while reverting to LGR5+ CSCs and contributing to tumour regrowth after LGR5+ CSC ablation. We also show that combined chemotherapy potentiates LGR5+ CSCs targeting. These data provide insights into the plasticity of CSCs and their potential as a therapeutic target in human colorectal cancer.
Project description:Transcriptome profiling using Affymetrix GeneChip arrays was performed on sorted populations of Lgr5-expressing mouse ovarian surface epithelium. The ovary surface epithelium (OSE) undergoes ovulatory tear-and-remodelling throughout life. Resident stem cells drive such tissue homeostasis in many adult epithelia, but their existence in the ovary has yet to be definitively proven. Lgr5 marks stem cells in multiple epithelia. Here we use reporter mice and Single Molecule Florescent-in-Situ-Hybridization (FISH) to document candidate Lgr5+ stem cells within the mouse ovary and associated structures. Lgr5 is broadly expressed during ovary organogenesis, but becomes limited to the OSE in early neonate life. In adults, Lgr5 expression is predominantly restricted to proliferative regions of the OSE and fimbria- mesovarian junction. Using conditional in vivo lineage tracing we identify embryonic and early neonate Lgr5+ populations as stem/progenitor cells contributing to the development of adult OSE and granulosa cell lineages, as well as the epithelia of the mesovarian and oviduct including its distal opening, fimbria. Long-term lineage tracing reveals that adult OSE-resident Lgr5+ populations contribute to epithelial homeostasis and OSE regenerative repair in vivo. Thus, Lgr5 is a marker of stem/progenitor cells of the ovary and tubal epithelia. Ovarian surface epithelium from pooled batches of Lgr5-eGFP-CreERT2 mice (n=8, per array) were sorted for cells expressing either high or low EGFP. Total RNA from three technical replicates per sorted population (Lgr5-high or Lgr5-low) was extracted with the RNeasy Micro Kit (QIAGEN), DNaseI-treated, and amplified with the Ovation Pico WTA V2 (NuGEN Technologies). Single-stranded cDNA amplification products were purified using QIAquick PCR Purification Kit (QIAGEN). cDNA was biotinylated using the Encore Biotin Module (NuGEN Technologies). Biotiylated cDNA was hybridized to Affymetrix Mouse Genechip ST 2.0 expression arrays.
Project description:The Toll-like receptor 4 (TLR4) pathway is important for tumor-initiating cells. We used microarrays to obtain gene profiling data in order to increase understanding of the pathways.