ABSTRACT
The cancer stem cell (CSC) model was fi rst described in blood cancer, acute myeloid leukemia (AML) (Bonnet and Dick, 1997; Lapidot et al., 1994), and since then has evolved in complexity with descriptions of CSCs in other tumors (Al-Hajj et al., 2003; Ricci-Vitiani et al., 2007; Schatton et al., 2008; Singh et al., 2004). The cancer stem cell hypothesis proposes that cancer is propagated by a subpopulation of cells with stem cell properties, namely the ability to proliferate while balancing self-renewal with differentiation, to maintain the cancer. The presence of CSCs provides an explanation for the biological heterogeneity of cells within a cancer.
