Lgr5-negative cancer cells seed metastases in colorectal cancerÂ

Cancer stem cells (CSCs) are a minority population of cancer cells that display stem cell-like multipotent and self-renewal properties. They give rise to the bulk of cancer cells with limited replicative potential. In colorectal cancer (CRC), CSCs are marked by expression of the leucine-rich repeat-containing G-protein receptor 5 (Lgr5). Since CSCs display multipotent and self-renewal properties, this population is thought to seed metastases. Here, we used a mouse model and human xenografts to investigate the cell-of-origin of metastases. Surprisingly, we found that most CRC cells that disseminated and entered the blood circulation were Lgr5-. Lgr5- cancer cells arriving at the metastatic site formed lesions in which Lgr5+ CSCs appeared. This plasticity could occur independently of stemness-inducing factors, and was an indispensable event for the outgrowth of metastases, since neutralization of this plasticity prevented metastatic outgrowth. Combined, our study shows that most metastases are seeded by Lgr5- cancer cells, and that these cells have a niche-independent and intrinsic capacity to become CSCs and restore epithelial hierarchy.Â