A distinct role for Lgr5 + stem cells in primary and metastatic colon cancer

Cancer stem cells are thought to maintain tumour growth, but evidence for their functional relevance is limited. Felipe de Sousa e Melo et al. study the role of Lgr5+ cancer stem cells in intestinal tumours in mice. Unexpectedly, they find that ablation of Lgr5+ cells prevents further growth of primary tumours, but tumours can continue to develop when Lgr5+ cell deletion is reversed. Metastasis of colon cancer to the liver is greatly impaired upon deletion of Lgr5+ cells. These findings shed new light on the role of cancer stem cells in the development of primary tumours and metastases.