Cancer stem cell

Cancer stem cells (CSCs) are cancer cells (found within tumours) that possess characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer. Although, the concept that cancer arises from ‘stem cells’ or ‘germ cells’ was first proposed some 150 years back, it is only recently that advances in stem cell biology has given new impetus to “cancer stem cell hypothesis”. Two important related concepts of this hypothesis are that I) tumours originate either in tissue stem cells or their immediate progeny through dysregulation of the normally tightly regulated process of self-renewal. As a result of this, II) tumours contain cellular sub-component that retains key stem cell properties. These properties include self-renewal, which drive tumourigenesis, and differentiation albeit aberrant that contributes to cellular heterogeneity. At the molecular level, the alteration of stem cell self-renewal pathway(s) has been recognized as an essential step for CSC transformation. Better understanding of CSC will no doubt lead to a new era of both basic and clinical cancer research, re-classification of human and animal tumours and development of novel therapeutic strategies specifically targeting CSCs.