Expression data of GFP-high or low cells of LGR5-GFP or KRT20-GFP knock-in human colorectal tumor organoids.

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.