The role of adult stem cells in carcinogenesis

The role of adult stem cells in tissue regeneration has attracted much interest because of its enormous therapeutic potential. Adult stem cells reside in every tissue of the body and have the ability to self-renew and to give rise to a high number of differentiated progeny. These are indeed the essential steps in tissue regeneration, which in some cases occurs constitutively, whereas in other cases happens in response to an injury. The identification of the key factors involved in self-renewal and differentiation pathways is at the top of the agenda of stem cell biologists. Interestingly, a number of factors that govern the fate of adult stem cells also play a role in malignant cell transformation, such as the Wnt cascade, Oct-4, Bmi-1 and Evi1. In addition, rare subpopulations of cancer stem cells were identified for leukemia and other solid tumors. These rare fractions of cancer stem cells are in large part responsible for maintaining the tumor mass, as they have the capacity to self-renew and to generate a high number of progeny via differentiation program. These findings can be considered a major breakthrough in cancer research. Currently, oncologists and stem cell biologists have two main goals: i) the assessment of the consistency of the line that divides adult stem cells and carcinogenesis; ii) to better characterize the biology of cancer stem cells. This new line of investigation may allow for the development of novel therapeutics and cancer diagnostics.