Telomerase and Cancer Stem Cells

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Stem cells as well as cancer stem cells are defined as cells able to both extensively self-renew and differentiate into progenitor cell types. Although embryonic stem cells and organ specific somatic stem cells both share the biological properties of self-renew and differentiation, the mechanism(s) to preserve these potential in stem cells are largely obscure. Accumulating evidence indicates that embryonic stem cells as well as undifferentiated-highly proliferating progenitor cells and germline cells express high levels of telomerase activity. As these cells differentiate into mature cells, the telomerase activity decreases. It is widely believed that this constitutive expression of telomerase is merely important for maintaining telomere homeostasis and this function of telomerase may contribute to the maintenance of self-renewal potential of stem cells. However, while telomerase activity and self-renewal potential correlate, recent evidence shows that telomere homeostasis and self-renewal potential are not necessarily linked. These observations suggest that telomerase expression in stem cells may play an important role to preserve self-renewal potential through mechanisms beyond telomere maintenance. We study the potential functional role(s) of telomerase/TERT in maintaining the self-renewal potential of cancer stem cells.