Small chromosome tips indicate that you are older than you
WWe all know how old we are chronologically. But do we know how old we are biologically? Everyone ages at different rates. Lifestyle, genetics, stress, and other factors contribute to keeping us younger than we look or ageing beyond our years. A tell-tale sign of the internal aging process can be found deep in each one of us, in minute strands of DNA proteins at the ends of each chromosome. For years, scientists have been studying the role that these chromosomal tips, called telomeres, play in measuring our biological age and how they affect the development of diseases, including cancer. One of the insights his research gained is that telomeres fuel cellular health and allow cells to grow. “They’re like little fingers on the end of DNA,” says Stephen Lynch, MD, a receptionist and primary care physician at our hospital near Phoenix. “It protects the cells and allows the cells to correct errors in the DNA during the process of cell division.
What are telomeres?
Telomeres have been likened to agate, the plastic or metal tips at the end of shoelaces that prevent fraying. When the thread is damaged or frayed, the rope begins to break. Telomeres shrink with each cell division or replication. As we age, telomeres become too small to protect the chromosome, and no longer prevent cell damage from occurring, and this can create a breeding ground for cancer cells. “Cancer is the end result of an evolutionary process called aging,” says Murray Markman, MD, chief of medicine and science at Cancer Treatment Centers of America. ® (CTCA). “It’s the end result of all the cell divisions, duplications, and mutations that occur over many years.”
So if telomeres shrink with age, and age is a major cancer risk factor, do longer telomeres reduce cancer risk? Researchers at the Dana-Farber Cancer Institute in Boston believe the answer may be yes, because they hypothesize that telomere length “may influence the rate of aging and the onset of age-related diseases.” Meanwhile, scientists at MD Anderson Cancer Center in Houston have concluded that short telomeres appear more frequently in cancer patients. Researchers studied telomere length in dozens of patients diagnosed with a variety of cancers. Their conclusion: “Shorter telomeres appear to be associated with an increased risk of bladder, head and neck, lung and kidney cell cancers.”
- Telomeres replicate the DNA sequences located on the ends of human chromosomes.
- Telomeres are made of base pairs, which are identical groups of nucleotides that make up the rungs of the ladder in the DNA helix. Telomeres can be up to 15,000 base pairs long.
- Each time a cell divides, its DNA loses up to 200 base pairs. The number of base pairs lost can depend on stress and other lifestyle influences.
Just as shorter telomeres have been linked to aging, disease and poor health, longer telomeres have been linked to a healthier lifestyle, which may reduce the risk of cancer. “Studies show that people who go a lot of miles tend to have longer telomeres,” says Dr. Lynch. “We know exercise is good and keeps you healthy. Well, maybe one of the reasons is that telomeres can help you keep your DNA healthy.” A study from the University of California, San Francisco (UCSF) concluded that lifestyle changes, including more exercise and an improved diet, can lengthen telomeres. “These findings suggest that telomeres can lengthen when people change their way of life,” author Dean Ornish, MD, professor of clinical medicine at the University of California, San Francisco, says in an article about the study. “
Unsurprisingly, this science has led to theories that telomeres can be manipulated to reverse aging. In a 2010 article published in the Harvard Gazette , scientists said they used telomerase, the enzyme that feeds telomeres, to reverse the aging process in mice. According to the researchers, the mice became significantly healthier when the enzyme was administered. Organs regenerated, brain cells became more active, and males regained their fertility. “What really surprised us was the dramatic reversal of the effects we saw on these animals,” says Ronald DePinho, a Harvard researcher and former president of MD Anderson.
In addition to feeding telomeres, telomerase is a powerful enzyme that can be found in many cells, including embryonic cells and active immune cells. But this enzyme is also present in cancer cells, raising concerns that rather than preventing age-related cancer, it may stimulate tumors. Despite research supporting the role of telomeres in healthy living, and despite multiple clinical trials exploring their role in cancer and other diseases, no evidence has been found to suggest that telomere research will lead to immortality or miracle cures. To date, the Fountain of Youth remains elusive. “We are not designed to last forever,” says Dr. Lynch. “Father Time is still undefeated.”