Project description:Mutations in APC or β-catenin that cause aberrant activation of Wnt signaling are responsible for the initiation of colorectal tumor development. LGR5 is specifically expressed in stem cells of the intestine, stomach and hair follicle, and plays essential roles in maintaining tissue homeostasis. LGR5-positive stem cells have been shown to be responsible for the intestinal adenoma initiated by some mutations in APC . Furthermore, it has recently been reported that Lgr5, which is associated with the Frizzled/Lrp Wnt receptor complex, interacts with R-spondins and thereby activates Wnt signaling. However, the function of LGR5 in colorectal tumorigenesis has been unclear. Here we show that LGR5 is required for the tumorigenicity of colorectal cancer cells. We also show that the transcription factor GATA6 directly enhances the expression of LGR5. DLD1 cells were infected with a lentivirus expressing an shRNA targeting GATA6 or LGR5.
Project description:Mutations in APC or β-catenin that cause aberrant activation of Wnt signaling are responsible for the initiation of colorectal tumor development. LGR5 is specifically expressed in stem cells of the intestine, stomach and hair follicle, and plays essential roles in maintaining tissue homeostasis. LGR5-positive stem cells have been shown to be responsible for the intestinal adenoma initiated by some mutations in APC . Furthermore, it has recently been reported that Lgr5, which is associated with the Frizzled/Lrp Wnt receptor complex, interacts with R-spondins and thereby activates Wnt signaling. However, the function of LGR5 in colorectal tumorigenesis has been unclear. Here we show that LGR5 is required for the tumorigenicity of colorectal cancer cells. We also show that the transcription factor GATA6 directly enhances the expression of LGR5.
Project description:This study has two components: (1) Human colon adenoma organoids (n=4 patients) were dissociated into single cells. Cells were incubated with a magnetic bead bound to an LGR5 antibody and run through a magnetic column. Magnet bound cells and flow through negative (FTN) cells were obtained. Magnet bound and FTN cells were incubated with an APC-check reagent (which binds to the magnetic bead on the LGR5 antibody) and DAPI, before being sorted by flow cytometry. 3 populations of live (DAPI-) cells were collected: FTN: Flow through negative. LGR5 negative by magnet and by flow cytometry SortedNeg: Magnet bound cells that were negative for LGR5 by flow cytometry SortedPos: Magnet bound cells that were positive for LGR5 by flow cytometry (2) Human colon organoids, as well as the tissue the organoid was derived from and adjcacent normal tissue (from n=19) were also profiled for known colorectal cancer associated mutations using the Qiagen Qiaseq Colorectal Cancer Panel, which provides targeted sequencing information for 71 genes.
Project description:We wanted to assess the role of Lef1 in ex vivo organoids using genetic mouse models of intestinal adenomas and scRNA-seq technology. Tumorigenesis was initiated by inducing Apc mutation in Lgr5+ stem cells. Intestinal cells of Lgr5-CreERT;Apc fl/fl (LApc) mouse and Lgr5-CreERT;Apc fl/fl; Lef1 fl/fl (LApcL) mouse were used to generate adenoma organoids. Organoids were cultured without growth factors for three passages and dissociated with Tryple express. We used WT mice as a control to distinguish adenoma cells. WT organoids were cultured with growth factors.
Project description:Somatic mutations in APC or CTNNB1 genes lead to aberrant Wnt signaling and colorectal cancer (CRC) initiation and progression. Activation of Wnt pathway leads to the formation of beta-catenin-T-cell factor/Lymphoid enhancer binding factor 1 (Tcf/Lef1) complexes that activate transcription of oncogenic target genes. Lef1 is the only member of the Tcf gene family that is not expressed in the normal intestine, but is induced during intestinal tumorigenesis. Thus, we wanted to assess the role of Lef1 using genetic mouse models of intestinal adenomas and scRNA-seq technology. Tumorigenesis was initiated by inducing Apc mutation in Lgr5+ stem cells. Intestinal EpCAM+ epithelial cells of Lgr5-CreERT;Apc fl/fl (LApc) mouse and Lgr5-CreERT;Apc fl/fl; Lef1 fl/fl (LApcL) mouse were used to analyze the effects of Lef1 deletion in intestinal adenoma cells. We used WT mice as a control to distinguish adenoma cells.
Project description:The generation of the Lgr5_EGFP_ires_CreERT2 knock-in mouse allows marking of Lgr5 positive cells of different tissues. Here we use these mice to sort Lgr5 positive cells and their daughter cells form intestinal adenomas and describe the expression profile of these two cell populations.
Project description:We isolated and selected intestinal adenoma organoids from Lgr5-EGFP-IRES-CreER; Apcflox/flox mice and added tamoxifen to induce the deletion of the Apc gene in the intestinal stem cells. Gene expressions on day7 and day20 after the addition of tamoxifen were compared, representing two stages with different colorectal cancer stem cell content. Total RNA obtained from Lgr5-EGFP-IRES-CreER; Apcflox/flox organoids were compared 7 days and 20 days after the addition of tamoxifen, cultured without the Wnt-agonist R-Spondin1.