Telomeres as a cause of ageing and cancer?

Are telomeres the cause of ageing and cancer?

The nuclei of our cells contain our genes, which are arranged along twisted, double-stranded DNA molecules called chromosomes. Sections of DNA at the edge of chromosomes are called telomeres, whose job it is to protect our genetic information so that cells can divide. However, they also contain secrets of how we age and get cancer.

Telomeres are sometimes compared to the plastic ends of shoelaces. They protect chromosome ends from fraying and sticking together, which would destroy or alter the organism's genetic information.

However, telomeres shorten with each cell division. If they become too short, the cell can no longer divide, becomes inactive, "ages" or dies. This shortening process is associated with the ageing process, cancer and an increased risk of death. For this reason, telomeres are also compared to the detonator of a bomb. 

What are telomeres?

Like the chromosomes and the genes themselves, telomeres contain sections of DNA - chains of the chemical code. Like all DNA, they consist of four nucleic acids: G stands for guanine, A for adenine, T for thymine and C for cytosine.

Telomeres consist of repeating stretches of TTAGGG on one strand paired with AATCCC on the other strand. So a section of telomeres is a repeating mix of these four base pairs.

In white blood cells, the length of telomeres varies from 8000 base pairs in newborns to 3000 base pairs in adults. Seniors only have 1500 base pairs. (A complete chromosome contains about 150 million base pairs.) With each division, an average cell loses between 30 and 200 base pairs at the end of its telomeres.

Cells normally divide between 50 and 70 times. The telomeres shorten more and more until the cell finally becomes senescent or dies.

Telomeres do not shorten in tissue cells because they do not divide constantly, as in the heart muscle, for example. 

Why do chromosomes contain telomeres?

Without telomeres, the main part of a chromosome - the part that contains vital genes - would shorten with each division. Telomeres enable cells to divide without losing genetic information. Cell division is necessary for the renewal of the skin, the formation of new blood cells, bones and other cells.

Without telomeres, chromosome ends would stick together and change the genetic blueprint of the cells. This would lead to malfunctions, cancer or death of the cell. Since damage to the DNA is so dangerous, cells have the ability to recognize and repair it on the chromosomes. Without telomeres, the chromosome ends would look like damaged DNA and the cell would try to repair damage that is not there at all. This would also result in the cell no longer dividing and dying over time.

Why do telomeres shorten with every cell division?

Before a cell divides, it makes a copy of the chromosomes so that both cells contain the identical genetic material after division. For this "copying process", the two DNA strands must unwind and separate from each other. An enzyme (DNA polymerase) then reads the two strands and builds two new strands. The process is supported by short pieces of RNA. After both new strands are finished, they are a little shorter than the original strands, as there has to be room for this short piece of RNA at the end. It's like someone painting the floor of a room and squeezing themselves into a corner. He can't paint this last piece. 

Telomerase counteracts the shortening of telomeres

An enzyme called telomerase adds bases to the end of the telomeres. In young cells, telomerase prevents the telomeres from wearing out too much. However, as the cells are constantly dividing, there is not enough telomerase, so the telomeres shorten over time and the cell ages.

Telomerase remains active in sperm and eggs, which are passed on from one generation to the next. If the cells required for reproduction did not contain telomerase to maintain the length of the telomeres, the organism would die very quickly.

Telomeres and ageing

Geneticist Richard Cawthon and his colleagues at the University of Utah found that shorter telomeres are associated with a shorter life. In the over-60 age group, those with shorter telomeres were three times more likely to die from heart disease. The risk of death from infectious diseases was even eight times higher.

A shortening of the telomeres has been linked to the ageing process. However, it is currently not known whether shortening telomeres is simply a sign of ageing - such as gray hair - or whether it actively contributes to the ageing process.

If telomerase causes cancer cells to become immortal, could it prevent normal cells from aging? Could we extend our lifespan by preserving or restoring telomere length through telomerase? If so, would this increase our risk of developing cancer?

Scientists do not yet have an answer to these questions. In the laboratory, however, they have already succeeded in maintaining the cell division of human cells far beyond the normal limit without these cells becoming cancerous.

If we could use telomerase to "immortalize" human cells, we might be able to mass produce cells for transplantation, including insulin-producing cells to cure diabetes, muscle cells to cure muscular dystrophy, cartilage cells for certain types of arthritis, and skin cells to treat severe burns and wounds. An unlimited supply of normal human cells - grown in the laboratory - would be a great help in testing new drugs and gene therapies. 

How great is the influence of telomeres on the ageing process? 

Some long-lived species such as humans have much shorter telomeres than mice, for example, and they only live for a few years. Nobody knows why. But it shows that telomeres alone are not responsible for life expectancy.

Cawthon's study came to the conclusion that people can be divided into two groups based on the length of their telomeres: Those with longer telomeres live on average five years longer than those with shorter telomeres. This study suggests that lifespan could be extended by five years by lengthening shorter telomeres.

Even in people with longer telomeres, these shorten as they grow older. How many years could we add to our life expectancy if we could stop telomere shortening completely? Cawthon believes it would be ten, maybe even 30 years.

After the age of 60, the risk of death doubles every eight years. This means that a 68-year-old is twice as likely to die within the next year as a 60-year-old. Cawthon's study comes to the conclusion that telomeres of different lengths are only responsible for four percent of this difference. And of course, intuition already tells us that older people have a higher risk of dying, but only six percent die exclusively due to age. If we add telomere length, age and gender (women live longer than men) together, these factors account for 37 percent of the risk of death in the over-60s. What causes the remaining 63 percent?

One of the main causes of ageing is "oxidative stress". This is damage to DNA, proteins and lipids (fats) caused by oxidants, i.e. highly reactive substances that contain oxygen. These oxidants are normally produced during respiration, but also as a result of inflammation, infections and alcohol and nicotine consumption. In one study, scientists exposed worms to two substances that neutralize oxidants. The life span of the worms then increased by an average of 44 percent.

Another factor in the ageing process is "glycation". Glycation occurs when glucose, our main source of energy, binds to parts of our DNA, proteins and lipids so that they can no longer do their job. The problem gets worse as we get older, leading to dysfunction in body tissues, which in turn leads to disease and death. Glycation is probably the reason why studies have shown that the lifespan of animals can be extended when their calorie intake is restricted.

It is therefore most likely that oxidative stress, glycation, telomere shortening and age - together with various genes - work together to age us.

Telomeres and cancer

If a cell becomes cancerous, it divides even more frequently, causing the telomeres to shorten considerably. If the telomeres are too short, the cell dies. Cells often try to avoid death by producing more telomerase enzymes to prevent further shortening of the telomeres.

Many types of cancer are associated with shortened telomeres, for example in the pancreas, bones, prostate and bladder, lungs, kidneys, head and neck.

Measuring telomerase may be one way to detect cancer. If scientists find a way to stop telomerase, it may be possible to fight cancer by allowing the cancer cells to age and die. In a laboratory experiment, researchers were able to block the activity of telomerase in human breast and prostate cancer cells, causing the tumor cells to die. However, this procedure also harbors risks. There are indications that blocking telomerase has a negative effect on fertility and wound healing as well as the production of blood and immune system cells.

Telomeres and other diseases

Patients suffering from dyskeratosis congenita have telomeres that shorten much faster than is normally the case. Those affected experience premature ageing and death. They have a higher risk of life-threatening infections, leukemia and other blood cancers, intestinal diseases, liver cirrhosis and pulmonary fibrosis, a stiffening of the lung tissue, which is fatal. They also develop gray hair or baldness earlier and suffer from poor wound healing. Age spots form on the skin, they suffer from intestinal diseases, bone softening and learning disorders. There is reason to believe that telomeres play a role in all these diseases, as tissue is affected whose cells divide frequently. There is also some evidence that shortened telomeres are linked to Alzheimer's disease, hardening of the arteries, high blood pressure and type 2 diabetes. 

What are the prospects for human immortality?

Human life expectancy has increased significantly since the early 17th century. The reasons for this significant increase are the construction of sewers and other sanitary measures, the development of antibiotics and the provision of clean water and cooling systems. Vaccinations and other medical advances are saving newborns and children from early death. Improved nutrition and better health care in general also contribute to longer life expectancy.

Some scientists believe that life expectancy will continue to rise, but most doubt that it will far exceed 90 years. However, a few believe that a significantly higher life expectancy is possible.

Cawthon believes that if all ageing processes could be stopped and all damage caused by oxidative stress could be repaired, "one estimate is that people could live to be 1000 years old." 

Lengthen telomeres with the right nutrients:

• B vitamins
• Turmeric
• Vitamin K2
• Magnesium
• Vitamin D
• Astaxanthin
• Ubiquinol Q10
• Probiotics
• Polyphenols

B vitamins (stress control and stress reduction)

Several studies have linked chronic stress to shorter telomeres. In a 2004 study, healthy mothers with healthy children (control group) were compared with those who raised chronically ill children (caregiving mothers). On average, the caring mothers had telomeres that were 10 years shorter than those of the control group. This means that their cells behaved as if they were a whole decade older.

In another study, which looked at African boys, it was found that the telomeres of those who grew up in a stressful environment were 40 percent shorter than those who came from stable backgrounds. 

What is the key point? Chronic stress doesn't just put you in a bad mood; it is an active and real contributor to your ageing process. Regular exercise, sufficient sleep and a little time for yourself every day are simple ways to reduce stress.

Vitamin B12 is commonly known as the "energy vitamin". Your body needs it for a whole range of vital functions. These include energy production, blood formation, DNA synthesis and the production of myelin.

The plasma concentration of vitamin B folate corresponds with telomere length. Folate plays an important role in maintaining the integrity of DNA and DNA methylation - both have an important influence on the length of your telomeres.

Turmeric (naturally against cancer)

Turmeric - the active ingredient in Indian turmeric - influences more than 100 different pathways as soon as it enters the cell. These include key biological pathways that are required for the development of melanoma and other cancers.

Vitamin K2 (blood clotting)

Most people consume enough vitamin K in their diet to maintain adequate blood clotting. However, they do not consume enough to effectively prevent serious diseases, including cardiovascular disease and cancer. Several studies suggest that vitamin K2 plays a key role in protecting against prostate cancer, which is one of the most common cancers in men in the US.

Magnesium (repair of DNA)

Magnesium is thought to influence telomere length because of its effects on DNA integrity and repair - in addition to its potential role in oxidative stress and inflammation.

Vitamin D (sun vitamin)

Researchers found that those with high levels of vitamin D generally have longer telomeres and vice versa. This means that people with high levels of vitamin D actually age more slowly than people with low vitamin D levels.

Astaxanthin (antioxidant)

In a 2009 study on the influence of the use of multivitamins on the length of telomeres, longer telomeres were linked to the use of antioxidants. The researchers wrote that telomeres are particularly sensitive to oxidative stress. In addition, inflammation triggers oxidative stress and reduces the activity of telomerase, the enzyme responsible for maintaining telomeres. Astaxanthin has been shown to be one of the most effective and beneficial antioxidants currently known. It has an anti-inflammatory effect and protects DNA.

Ubiquinol (reactivation of antioxidants)

Premature ageing is one of the main side effects of too little CoQ10 This essential vitamin replenishes other antioxidants such as vitamins C and E. Too little CoQ10 contributes to an acceleration of damage to the DNA. CoQ10 also has a very positive effect on heart health and muscle function. A deficiency leads to fatigue, muscle weakness, pain and ultimately heart failure.

Probiotics (fermented foods)

Processed foods high in sugar and full of chemicals are very effective in destroying your gut flora, which has an immeasurable impact on your immune system. When you destroy your body's natural defense system, you put yourself at risk of disease and premature aging. Ideally, you should make traditionally grown and fermented foods an important part of your diet to keep your gut flora healthy. Fermented vegetables are an excellent alternative to processed foods. Not only are they delicious, they are also easy to prepare at home.

Polyphenols (secondary plant substances)

Polyphenols are effective antioxidants in plant foods. Many of them have proven to be effective in preventing diseases and also have an "anti-ageing effect". Resveratrol is found, for example, in grapes (muscatel), unprocessed organic cocoa beans and green tea. 

 

Sources (in English):

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