Cancer stem cells: characteristics and their potential role for new therapeutic strategies.

With the cancer stem cell (CSC) hypothesis many questions regarding cancer development and drug resistance can be answered more coherently than with the traditional model based on clonal evolution. CSCs are a small subset of cancer cells within the tumour that show stem cell characteristics like self-renewal, the capability to develop into multiple lineages and the potential to proliferate extensively, and are characterised by a typical profile of different markers like CD44 and CD133. In the CSC model, the role of embryonic pathways like Wnt, Hedgehog and Notch is of special interest. This review presents current scientific knowledge on this topic and discusses the potential role of CSC in the resistance against chemotherapy or radiation and presents challenging options for therapeutic interventions.