Analyzing the effect of Lef1 deletion in mouse intestinal adenoma cells with single-cell RNA sequencing

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. Single-cell RNA sequencing was performed on mouse intestinal EpCAM+ epithelial cells. We deleted Apc with and without Lef1 in the Lgr5+ stem cells of Lgr5-EGFP-IRES-CreERT2;Apcfl/fl;Lef1fl/fl (LApcL) or Lgr5-EGFP-IRES-CreERT2;Apcfl/fl (LApc) mice and performed scRNA-seq at time points when they met the criteria for euthanization. WT mouse was used as a control.