Cell fate dynamics in intestinal homeostasis and cancer

Abstract

In conclusion, the studies presented in this thesis contributed to the field of cell fate dynamics in human CRC and its metastasis. We developed novel reporters and strategies to study functional intratumoral heterogeneity and cellular hierarchies in human CRC. One of these reporters is the STem cell ASCL2 Reporter (STAR), which functions as a marker for intestinal stem cells and colorectal cancer stem cells. Focusing on CSC and non-CSC fate, we demonstrated the interdependency between these two cell fates. Future research should determine what kind of biological cues and molecular characteristics influence CSC and non-CSC fate, and how this is changed under therapeutic conditions. PDTO cultures are very important to increase our insights into the basic principles of cell plasticity in healthy intestinal and cancerous tissue. However, we have to take into account that phenotypes can be affected by culture conditions. Validation experiments using orthotopic transplantation in mice is therefore of outmost importance. In contrast, dedicated perturbations of organoid cultures via minor modifications of the culture medium also demonstrate the power of the model system. Especially when large quantities of cellular material is required that precludes FACS, guided differentiation protocols for cell-type enrichment is a valid strategy to obtain high resolution multi-omics data. Studies presented in previous chapters demonstrate that combining techniques, technologies, and strategies will help us to understand the reversibility of phenotypes and its correlation with genotype. In more detail it provides clues about what the causes and consequences are of functional intra-tumor heterogeneity. This eventually paves the way to translate acquired fundamental insights of cellular fate plasticity from patient-derived (colorectal) cancer organoids to investigate whether manipulation of cell fate plasticity can improve cancer therapies.