Human breast and melanoma cancer stem cells biomarkers

Cancer progression in humans is difficult to infer because we do not routinely sample patients at multiple stages of their disease. The identification cancer stem cell (CSC) subpopulations inside tumor opens a new view of cancer development, since it implies that tumors can only be eradicated by targeting CSCs. Several markers have been proposed in the literature to identify CSCs both in breast and melanoma but no consensus has been reached, leading to the hypothesis that the CSC phenotype might be dynamically switched. Herein we provide a critical discussion of the biological markers described in the literature for breast cancer and melanoma. Due to its complexity the field would benefit from an interdisciplinary approach to investigate tumor heterogeneity and its progression. Similar considerations could also be relevant for normal tissue stem cells.