of infectious disease than those with lon -ger telomeres.” 6 Telomeres’ accomplice in aging is the enzyme telomerase. Telomerase, some -times referred to as an immortalizing en -zyme, protects and stabilizes telomeres “similar to plastic tips on shoelaces.” 7 It maintains telomeres in our reproduc -tive and stem cells but not in the rest of the body and is part of a compensa -tory system for the cellular shortening of telomeres. 8 In a recent break-through study, it was found that, as well as help -ing keep telomeres from deteriorating, it also reverses the aging of telomerase-deficient rats. In a transformation the lead researcher described as “akin to a Ponce de León effect,” lies the first compelling evidence of aging reversal in a high-level organism. 9 a faustian Bargain So far, so good. Like all “pact with the dev -il” stories, however, the neat relationship between telomeres and their companion lengthening enzyme comes with a catch. In Christopher Marlowe’s Renaissance play, The Tragicall History of the Life and Death of Doctor Faustus, Faustus deeds his soul to Lucifer in exchange for lim -itless knowledge. The deal includes the services of the sub-devil Mephistophilis, nominally Faustus’s servant but in real -ity his master. In time, Faustus comes to appreciate that the deal fell short of his expectations and that knowledge without wisdom is mortally dangerous. The devil’s fine print here is in the unsettling relationship between telom -erase and cancer. Theoretically, boosting telomerase activity would continuously renew our telomeres and thereby slow aging or stop it altogether. However, ac -tivation of telomerase appears to be re -sponsible for the sustained growth and malignancy of many tumours. It also confers immortality on cancer cells. “In immortal cancer cells, telomeres act ab -normally – they no longer shrink with each cell division,” enabling them to replace lost sequences and divide in -definitely. 10 Although telomerase is not present in most cells, it gets reactivated in cancer cells, so telomerase-enhancing treatments aimed at slowing aging might also increase the risk of cancer. “As with all of our other genes, the DNA that encodes the telo merase enzyme is present in all of our cells – but because 22 • CANADIAN CHIROpRACTOR | DECEMBER 2011 it’s needed only after quite a few cell di -visions have occurred, it’s not needed in most cells for most or all of the time, so it’s turned off. This widespread lack of the need for telomerase is used by evolution as a key component of our defence against cancer, because having a limit to the size and renewal of telomeres prevents our cells from replicating themselves indefi -nitely – the crucial hallmark of cancer.” 11 Studies in mice have shown that elevated telomerase activity leaves the animals more susceptible to skin tumours and breast cancer. Conversely, blocking the enzyme causes “any and all the aspiring cancers we developed to fizzle out before they became life-threatening indeed, be -fore many of them even became actual cancers.” 12 So we are faced with a Faustian bar -gain: enhance telomerase activity and slow aging but potentially heighten our odds of developing cancer. Reduce or eliminate telomerase altogether and maybe do away with cancer as a killer among humans but at the cost of accel -erating our decline with age and possibly cutting short our own modest life span. The deeply interwoven relationship be -tween telomeres and telomerase in aging and cancer promises both will remain the subject of near hypnotic fascination for years to come. balance and other aspects of psycho -logical well-being in health professional education. We will look at some of these questions in the context of quality-of-life issues later in our exploration of aging and longevity. In Part 2, we will examine other factors in the aging and longevity discussion, strate-gies to promote longevity and genetic deter-minants of life span. • BEyonD immortality Telomere-centred research has invited far-reaching speculation around the en -ticing possibility that, by halting the pro -cesses of senescence, we may one day be able to engineer indefinite human life spans with no biologically fixed termini. The role of telomeres in aging and health, however, also has implications across a number of disciplines, not least of which, is chiropractic. At the 2011 Canadian Memorial Chiropractic College Research Symposium, for example, Dr. Aviad Ha -ramati of Georgetown University looked at the place of mind-body medicine in the training of health professionals. His research references factors such as accel -erated telomere shortening in response to life stress, perceived stress and telo -mere length, and possible pathways by which chronic stress impacts telomeres. Research of this kind raises provocative questions about the nature and timing of health-care provider interventions as well as the role of stress management, lifestyle rEfErEnCEs 1. National Institute on Aging, National Institutes of Health (US). Aging under the microscope: a biological quest. 2006. NIH Pub. No. 02-2756: 6. 2. Ibid. 3. Shay, JW. Aging and cancer: are telo-meres and telomerase the connection? Molecular Medicine Today, Reviews. 1995 Nov; 1(8):379. 4. National Institute on Aging, National Institutes of Health (US). Aging under the microscope: a biological quest. 2006. NIH Pub. No. 02-2756: 16. 5. Cawthon RM, Smith KR, O’Brien E, Sivatchenko A, Kerber RA. As-sociation between telomere length in blood and mortality in people aged 60 years or older. Lancet. 2003 Feb 1; 361(9355):393-5. 6. Greenwood, V. What will our telomeres tell us? Discover Magazine. 2011 May 18. Available from: http://discoverma-gazine.com/2011/may/18-what-will-our-telomeres-tell-us 7. Shay, JW. Aging and cancer: are telo-meres and telomerase the connection? Molecular Medicine Today, Reviews. 1995 Nov; 1(8):379. 8. Katrin, Susan. Can a pill keep your DNA young? Discover Magazine. 2010 June 11. Available from: http:// discovermagazine.com/2010/may/20-can-a-pill-keep-your-dna-young 9. Keim, B. Telomere tweaks reverse ag-ing in mice. Wired Science. 2010 Nov 29. Available from: http://www.wired. com/wiredscience/2010/11/mouse-aging-reversal/ 10. National Institute on Aging, National Institutes of Health (US). Aging under the microscope: a biological quest. 2006. NIH Pub. No. 02-2756: 16. 11. De Grey, A, Michael R. A modest proposal: how to stop aging entirely. Discover Magazine. 2009 September 23. 12. Ibid. www.canadianchiropractor.ca
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