Cancer Stem Cells and Macrophages: Implications in Tumor Biology and Therapeutic Strategies

Figure 1

The CSC model. Over time, CSCs acquire phenotypes and characteristics of normal stem cells such as unlimited self-renewal and the capacity to divide indefinitely and at the same time maintain the ability to generate multiple cell lineages, including differentiated progenies. A CSC can thus divide (1) asymmetrically (differentiation) giving rise to one CSC and a specialized differentiated cell or (2) symmetrically (self-renewal) giving rise to two identical CSCs. In both cases, the capacity of self-renewal remains intact and ensures the survival of the CSC pool and supports the hierarchical model of tumor cell heterogeneity.