Lineage Tracing Reveals Lgr5 + Stem Cell Activity in Mouse Intestinal Adenomas

Cancer Stem Cells in Color One of the liveliest debates in contemporary cancer research centers on whether cancer stem cells (CSCs) exist and, if so, how these cells are defined phenotypically. CSCs are hypothesized to be a small population of cells within a tumor that are endowed with the unique capacity to drive tumor growth—a scenario that in principle would offer important therapeutic opportunities. By studying mice expressing multicolor reporter genes, Schepers et al. (p. 730 , published online 1 August) were able to visualize and monitor the fate of a candidate stem cell for intestinal adenomas, an early stage of cancer. This “lineage tracing” analysis suggests that tumor cells expressing the intestinal crypt stem cell marker Lgr5 (leucine-rich repeat containing G protein–coupled receptor 5) are the cells that fuel the growth of intestinal adenomas.