Telomeres at the nexus of aging, tumor suppression, and inflammation: toward an understanding beyond senescence.

Aging is the greatest risk factor for most diseases. We propose that aging manifests as disease as a function of tumor-suppressive capabilities. Adequate tumor suppression results in cell death or an accumulation of damaged cells leading to inflammation and tissue dysfunction that underlies diseases such as cardiovascular disease, neurodegenerative diseases, or type 2 diabetes. Conversely, inadequate tumor suppression leads to cancer. Telomeres are central to this process because they oppose hyperproliferation that is required for cancer initiation by enforcing two potent tumor suppressor mechanisms: senescence and crisis. Although senescent cells promote age-related diseases via inflammatory signaling, crisis cells have lost the p53 and RB pathways, have more unstable genomes, and harbor shorter telomeres, all of which could increase inflammation to a greater degree than is seen in senescence. This model emphasizes the intimate relationship between aging, telomeres, tumor suppression, and inflammation and suggests that crisis cells may represent an unexplored driver of inflammation in advanced age.