Figure 3.

Gene editing applications in organoids. (a) Genetic knock-in of a rainbow reporter construct and a Cre-recombinase under the control of a stem-cell-specific promotor enables genetic tagging of individual stem cells and their descendants (b) Tumor development can be recapitulated in vitro by introducing oncogenic mutations to normal organoids, for instance by CRISPR/Cas9. Starting with non-malignant organoids, the step-wise addition of oncogenic alterations results in a panel of gradually more malignant organoids, enabling the study of tumorigenesis with its intermediate states. (c) Pooled genome-wide lentiviral CRISPR knockout screens in organoids are invaluable tools to identify candidate genes involved in complex biological processes driving carcinogenesis and/or resistance development. *: oncogenic mutations.