Visualization and targeting of LGR5+ human colon cancer stem cells

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 targeting of LGR5(+) CSCs. These data provide insights into the plasticity of CSCs and their potential as a therapeutic target in human colorectal cancer.

癌症干细胞（CSC）理论强调了癌细胞中一个能自我更新的亚群，它推动了肿瘤的生长。人类癌症干细胞的存在主要通过对前瞻性分离细胞的异种移植得到支持，但其克隆动态和可塑性仍不清楚。在此，我们表明人类LGR5（+）结直肠癌细胞在生长的癌组织中充当癌症干细胞。利用他莫昔芬诱导的LGR5 Cre敲入等位基因进行的谱系追踪实验揭示了LGR5（+）肿瘤细胞的自我更新和分化能力。在LGR5 - iCaspase9敲入类器官中选择性清除LGR5（+）癌症干细胞会导致肿瘤消退，随后由重新出现的LGR5（+）癌症干细胞驱动肿瘤再生长。KRT20敲入报告基因标记了在肿瘤组织中不断减少的分化癌细胞，而在LGR5（+）癌症干细胞清除后，这些分化癌细胞会恢复为LGR5（+）癌症干细胞并促进肿瘤再生长。我们还表明联合化疗增强了对LGR5（+）癌症干细胞的靶向作用。这些数据为癌症干细胞的可塑性及其作为人类结直肠癌治疗靶点的潜力提供了见解。