Phenotypic plasticity: the emergence of cancer stem cells and collective cell migration

In this chapter, we discuss recent advances on the plasticity of cancer cells, focusing on their relevance for the metastatic process. We fist discuss the how cancer cells can switch back into cancer stem cells, breaking the strict hierarchy of cancer cell populations that was postulated earlier. In particular, the depletion of cancer stem cells compartment induces other tumor cells to switch back into cancer stem cells. We also discuss the phenotypic switching of senescent cells in cancer cell populations and the transition between epithelial and mesenchymal phenotypes. Our computational analysis combined with the analysis of transcriptomic data shows the presence of an infinite hierarchy of intermediate hybrid states with epithelial and mesenchymal character. Finally, we discuss phenotypic transformations induced by environmental and physical cues that lead to states of collective cell migration.