Tracing oncogene-driven remodelling of the intestinal stem cell niche

Interactions between tumour cells and the surrounding microenvironment contribute to tumour progression, metastasis and recurrence 1 – 3 . Although mosaic analyses in Drosophila have advanced our understanding of such interactions 4 , 5 , it has been difficult to engineer parallel approaches in vertebrates. Here we present an oncogene-associated, multicolour reporter mouse model—the Red2Onco system—that allows differential tracing of mutant and wild-type cells in the same tissue. By applying this system to the small intestine, we show that oncogene-expressing mutant crypts alter the cellular organization of neighbouring wild-type crypts, thereby driving accelerated clonal drift. Crypts that express oncogenic KRAS or PI3K secrete BMP ligands that suppress local stem cell activity, while changes in PDGFR lo CD81 + stromal cells induced by crypts with oncogenic PI3K alter the WNT signalling environment. Together, these results show how oncogene-driven paracrine remodelling creates a niche environment that is detrimental to the maintenance of wild-type tissue, promoting field transformation dominated by oncogenic clones.