Telomere dysfunction suppresses cancer through the p53 tumor suppressor pathway but also contributes to aging. A new study suggests that these effects of dysfunctional telomeres may be separable, such that aging—but not cancer suppression—depends on the p21 cell cycle inhibitor.
Introduction
The 'cancer-aging hypothesis' proposes that neoplastic disease and the age-induced degeneration of many organs are closely linked by the failure or success of tumor suppressor mechanisms such as cellular senescence. For example, activation of the p16 tumor suppressor in self-renewing compartments such as hematopoietic stem cells (HSCs) seems to contribute to aging1, yet inactivation of p16 is an early step in the formation of many cancers2. An important prediction of the cancer-aging hypothesis is that certain well-intended efforts to prevent aging (growth hormone replacement to retard muscle loss, for example) may accelerate cancer formation, and vice versa. Work from Aaheli Roy Choudhury and colleagues on page 99 of this issue3 is therefore surprising in that it shows that deficiency of the p53 effector p21 extends longevity and rescues stem cell function in mice with dysfunctional telomeres, without sacrificing tumor suppression.