Article Written by Jihan Noor for Biomed Middle East
Undoubtedly, the ultimate desire of every human being is to lead a long healthy life. Millions of people spend an appreciable amount of their money on Anti-aging Products, Hair Dyes, Surgery etc just to stay youthful externally.
But are these a solution to slow aging? Have you ever wondered what causes our body to age? How could we slow or possibly stop aging? Exercise has long been viewed as an important factor for maintaining health and vitality in old age.
But how does exercise have an impact on the aging process? The answer to these questions may lie in a tiny portion of our chromosomes known as Telomeres. This article provides an insight into telomere research and its association with aging and cancer.
What are Telomeres?
The long thread-like DNA molecules that carry our genes are packed into chromosomes. A telomere is a region of repetitive DNA at the end of a chromosome which protects the chromosome ends from destruction. In short, they serve as protective caps that prevent chromosomes from fusing with each other or rearranging that would scramble an organisms genetic information and cause cancer, other diseases or death . Telomeres are often compared to aglets (tips) on the ends of shoelaces that keep them from fraying.
Telomere and aging.
Over your lifetime, cells divide over and over to keep the body alive, but with each cell division, the telomeres get shorter. Eventually when they become too short, they potentially unfold from their presumed closed structure. It is thought that the cells detects this uncapping as DNA damage and lapse into a state called cellular senescence or apoptosis depending upon the cells genetic backround.Vital tissues are no longer produced and organs begin to fail.
In other words shorter the telomeres become, the more quickly cells die and therefore the shorter a persons life span.
Advocates of human life extension promote the idea of lengthening the telomeres in certain cells through activation of an enzyme known as ‘telomerase’.
Telomerase is a natural enzyme that repairs and lengthens telomeres. Most of the somatic cells express telomerase in very low levels in a cell cycle dependant manner but it is highly expressed in cells that need to divide regularly, for example in the immune system cells, stem cells, germ cells, hair follicles and in 90% of cancer cells. Telomerase help maintain telomere length thereby delaying cellular senescence. Hence telomerase activity slows aging process. Researchers are now working on temporary activation of telomerase(by drugs) or possibly permanently by gene therapy. They reason that this would extend human life.
A variety of premature aging syndromes are associated with short telomeres. These include Werner syndrome, Ataxia telangiectasia,Bloom syndrome,Fanconi anemia, Nijmegen breakage syndrome etc.The genes that have been mutated in these cases all have roles in the repair of DNA damage, and their precise roles in maintaining telomere length are an active area of investigation.
Telomere and cancer.
Cancer cells possess the property of indefinite proliferation. As a cell begins to become cancerous, it divides more often and its telomeres become very short. If its telomeres get too short, the cells may die. It can escape this fate by activating telomerase enzyme which prevents the telomeres from getting even shorter.
In this way cancer cells achieve cellular immortality. Telomerase is responsible for cellular immortalization in 90% of the cancers. However a sizeable fraction of cancerous cells employ alternating lengthening on telomeres(ALT),a non-conservative telomere lengthening pathway involving the transfer of telomere tandem repeats between sister chromatids.
Studies have found shortened telomeres in many cancers including pancreatic, bone,prostate ,bladder, lung and kidney, and head and neck. Cancer cells show high a high telomerase activity. If scientists can learn how to stop telomerase, they might be able to fight cancer by making cancer cells age and die.
In one experiment, researchers blocked telomerase activity in human breast and prostate cancer cells growing in the laboratory, promoting the tumors cells to die. But there are risks. Blocking telomerase could impair fertility, wound healing and production of blood cells and immune system cells. Experimental drug and vaccine therapies targeting active telomerase have been tested in mouse models, and some have now entered early clinical trials.Geron corporation is currently conducting four human clinical trials involving telomerase inhibition and telomerase vaccination.
The Lasker Award(2006) and the 2009 Nobel prize for Physiology and Medicine was awarded to three American Scientists-Elizabeth H.Blackburn,Carol W.Greider and Jack W.Szostak-for their discovery on how chromosomes are protected by telomeres and the enzyme telomerase.
How does exercise have anti-aging benefits?
A new study published in the journal of the American Heart Association Circulation has found that long term exercise fights the aging process through its effects on chromosomes. Intensive exercise helps prevent shortening of telomeres. The researchers measured the length of telomeres in blood samples from two groups of professional athletes-professional runners with an average age of 20 and middle-aged athletes with a history of continuous endurance exercise since their youth whose average age was 51.
The exercisers were matched by age to two groups who were healthy nonsmokers, but not regular exercisers.”The most significant finding of this study is that physical exercise of the professional athletes leads to activation of the important enzyme telomerase and stabilizes the telomere” according to lead author Dr.Ulrich Laufs of Saarland University in Homburg, Germany.
Physical exercise improves cardiovascular health and helps prevent cancer. Apart from fighting infections White blood cells have another major role which is seek out abnormal cell growths and clear them away. One reason why cancer increases with age could be that WBC themselves age and become less efficient at dealing with the abnormal growths.
If exercise maintains the youthfulness of WBC by preventing the shortening of their telomeres, it can explain why exercise can protect against cancer. Likewise with heart disease, aging WBC (along with high blood pressure and other factors) may allow plaque to accumulate more quickly. By keeping WBC young, exercise may enable them to continue to effectively clear away plaque.
In another study conducted in2008 by Dr. Ornish of the Preventive Medicine Research Institute, Sausalito, California and colleagues at the university of California Sanfrancisco,conducted a study of 30 men with low-risk prostate cancer, on the possible effects of lifestyle changes in telomers.The men were asked to make several social, dietary and exercise-related lifestyle changes.
Telomerase levels were measured at the baseline, and again after three months, when researchers discovered that, in 24 participants telomerase in the blood had increased by 29 percent. The authors commented that” The implications of this study are not limited to men with prostate cancer.
Comprehensive lifestyle changes may cause improvements in telomerase and telomeres that may be beneficial to the general population as well”.
The future prospects of Telomere research may someday aid in developing a longevity pill that will help fight aging and aging related disease and extent life span significantly or perhaps a drug or vaccine that will cure cancer.