CANCER. A word that no one ever wants to hear. Well guess what – your body doesn’t want to hear it either. From as early as birth your body does everything it can to prevent uncontrolled cell growth and the formation of mutations within cells. A tumor suppressor protein called p53 is responsible for such regulation. One of its roles in the body is to prevent tumor formation as its name suggests. More specifically, p53 responds to cellular damage in one of three ways: transient cell cycle arrest, cell death or permanent cell cycle arrest. Transient cell cycle arrest occurs when a slightly damaged cell is ‘stopped’ momentarily until the damage is fixed; at this time the cell may re-enter the cell cycle and continue dividing to form new cells. Cell death, or apoptosis, occurs when a cell is severely damaged beyond repair; the cell is destroyed so that it may never re-enter the cell cycle. Permanent cell cycle arrest, or cellular senescence, occurs when certain cell types are severely damaged; senescence differs from apoptosis in that the cells are not destroyed but rather permanently ‘stopped’ in the cell cycle. Senescent cells are also capable of acquiring abnormal functions which alter the environment of the tissue.
A tumor may form a) if p53 does not properly repair any damaged DNA within a cell and the mutations continue to accumulate, b) if p53 is itself defective and does not make proper decisions for the cells, or occasionally c) if cells take on unusual functions and alter the tissue environment. Each of these three situations are avoided by p53 for as long as possible. However, this is not a perfect process. Due to the fact that apoptosis and senescence permanently remove cells from the cell cycle they therefore deplete renewable tissues. If cells that are normally dividing to produce new cells are removed from the specific tissue, that tissue will slowly waste away. This depletion is what we term ‘aging’.
Although we generally view aging as an unwelcome process, it definitely beats having cancer. The longer that p53’s apoptosis and senescence mechanisms are working, the longer we can prevent the accumulation of mutated cells; the longer we prevent this accumulation, the longer we prevent cancer. So, my advice? Next time you notice that you are aging and you want to make a disgruntled comment – stop and take a moment to thank your body for putting off cancer for another day.
Pick Your Poison: Aging or Cancer
