- The Tale of the Telomere
- June 1998
- Dear Friends
Telomeres, are structures within the cells of all living plants and animals that control the aging process. Telomeres are also involved in cell alterations which result in cancer. The length of life of our body's cells has something to do with how many times the basic cells can divide and replace themselves. The number of cell divisions has been believed to be controlled by a biological clock, so that after so many divisions, let's say, around fifty, cells die, even though they have the same nutrients. By contrast, cancer cells never die. Thus, the price of cellular immortality is malignancy. The problem in cancer is that normal cell death and replacement does not occur. The concepts of senescence and malignancy appear to be contradictory, since similar fundamental biological processes control both. Can telomeres be both altered so that sequence can be delayed, i.e., length of life extended, and at the same time, cancer avoided? No one knows the answer to this question, but the understanding of fundamental biological processes now taking place in many laboratories suggests that this may be the case.
The longest anyone has ever lived is 122 years. How anyone can live this long has baffled scientists. Is length of life increasing? In large populations, the answer is no. Careful data has been kept in Scandinavian countries since the beginning of this century. The same number of people, approximately one in 100,000, live to be 100. But in this century, the average age of death has increased about twenty years. So what we are doing in medicine, is preventing premature morbidity and mortality, rather than extending the boundaries of life.
Fundamental factors in the aging process is the creation of free radicals, or oxidants, produced in the process of energy production as food is oxidized. Energy is necessary for the sustenance of life of cells and organs. Antioxidants, available through food and vitamins, may postpone this process. The most important ways to prevent premature aging of critical organs such as in emphysema and atherosclerosis, is to stop smoking and to lower cholesterol. Thus, we must also consider the interrelationship between environmental and behavioral factors in the process of aging and death.
When I fish in the Northwest Territories for giant lake trout, I marvel at the fact that each fish is two years old for each pound weighed. So, a twenty-five pounder is fifty years old. Naturally, I want to return these magnificent trout to the water. You can tell the age of the trout by counting the growth rate on the scales, just as one counts the rings of a tree. In this cold environment, these fish do not grow for a large part of the season, in the deep freeze of their environment. Growth is at the cost of free radical production, which in turn relates to age. We humans, being warm-bodied, do not enter a annual deep freeze. Thus, we must begin to understand how we age via cruise control and what we can do to extend the frontier of our lives. The genes that control our cellular functions have been given us at the moment of conception. How we can modify our allotted time is partly up to us.
I will be in touch next month.
- Thomas Petty, MD