Tracking the cells of tumor origin in breast organoids by light sheet microscopy

How tumors arise from individual transformed cells within an intact epithelium is a central, yet unanswered question. Here, we developed a new methodology that combines breast tissue organoids, where oncogenes can be switched on in single cells, with light-sheet imaging that allows us to track cell fates using a big-image-data analysis workflow. The power of this integrated approach is illustrated by our finding that small local groups of transformed cells form tumors while isolated transformed cells do not.