Cancer Stem Cells in Tumour Evolution

Abstract

It is hypothesised that the cells making up a cancer can be subdivided into two functional types: cancer stem cells (CSCs) that are capable of self-renewal and so are responsible for the driving the growth of the cancer, and non-CSCs that have a restricted life-span and so do not propagate the cancer in the long term. Here we critically assess the evidence for a population of CSCs in primary tumours, making particular note of the limitations of current methodologies used to study CSCs. We consider how clonal evolution occurs in cancers with CSC architecture and ask how evolution would shape the balance of CSCs to non-CSCs in a tumour. We also deliberate implications of the CSC hypothesis for understanding the evolutionary response of a cancer to therapy. We propose a series of questions to address the uncertainties that undermine the CSC hypothesis.