Recent progress in understanding the relationships among aging, replicative senescence, cell turnover and cancer.

The link between aging and cancer is more than just the increasing accumulation of mutations with time. Recent research provides evidence that senescent cells are not merely passive bystanders, but may promote cancer through degradation of the tissue microenvironment. Another critical factor in the relationship between aging and cancer is p53 function; its activity level is apparently finely tuned to suppress cancer while regulating both apoptosis and the replacement of damaged cells through stem cell proliferation. The deacetylase activity of the sir2 gene product plays a role in longevity regulation in invertebrates, and also regulates p53 function in mammals, implying yet another link between aging and cancer in mammals.