Cancer in the human body can arise for a variety of reasons, such as the consumption of food carcinogens, smoking, alcohol abuse, polluted air, etc. It is now known that cancer is a very ancient disease. Perhaps dinosaurs also suffered from cancer, at least this is indicated by some fossils of extinct reptiles. But why did cancer arise at all? Did animals really initially evolve in such a way that this deadly disease could appear in the body? Most likely, the reason is not evolution, but ancient viruses that our ancestors once suffered from.
Cancer may be caused by ancient viruses that hide in the human genome. Photo source: www.techinsider.ru
Contents
- 1 How viruses affect the body
- 2 Why cancer occurs
- 3 How ancient viruses help cancer develop
- 4 Why the risk of cancer increases with age
How viruses affect the body
When we get a viral infection, our body immediately begins to fight it and destroys viruses until they disappear completely. However, there are situations when even after recovery, viruses leave particles of themselves in the body in the form of DNA fragments. They do not manifest themselves in any way, so they do not interfere with the body's functioning at all.
Thus, some viruses hide in our genomes and are passed down from generation to generation for many years. For a long time, scientists considered them completely incapable of influencing the body in any way. It was assumed that “junk” DNA was simply some kind of viral trace inherited from our ancient ancestors.
Some viruses leave their mark on the human genome. Image source: theconversation.com
However, scientists have since discovered that these viruses can be “switched on” again, causing certain changes in the body. For example, one recent study found that this “junk” DNA is what gave rise to mammals, as endogenous retroviruses, or ERVs, spurred the evolution of the placenta. This means that without these “zombie viruses,” humans would never have emerged. Now, research has shown that these viruses may be linked to cancer.
Why Cancer Occurs
University of Colorado researchers have discovered that «zombie viruses» can significantly influence various modern diseases. But, most surprisingly, cancer cells can use some parts of these viruses to their advantage.
Cancer development requires “support” at the gene level. Image source: onkotver.ru
As you know, malignant cells are always present in the body, but the immune system suppresses them, so they do not develop into cancer. Oncology occurs only when certain changes occur in the body that contribute to the disease. In particular, it is known that cancer cells express (activate) many genes that should not be turned on.
Scientists for a long time could not understand what exactly “turns on” the genes that help cancer develop. Now, researchers have discovered that many gene “activators” come from zombie viruses.
How Ancient Viruses Help Cancer Grow
In the study, the scientists analyzed data sets from more than 20 different types of cancer and found that a family of ERVs called long terminal repeat 10 (LTR10) is active in these diseases. This virus is known to have infected our primate ancestors about 30 million years ago.
Ancient Virus Infected Primates 30 Million Years Ago. Image Source: www.earth.com
Having discovered the virus's activity, the researchers studied in detail the processes that occur at the gene level in colorectal cancer. As it turned out, LTR10 regulates the expression of genes that play an important role in the development of tumors.
When the researchers knocked out the LTR10 genes in colorectal tumor cells in mice, they also knocked out genes that cause cancer to grow and become resistant to therapy. As a result, after knocking out LTR10, the mice's tumors began to shrink and respond to treatment, the researchers reported in the journal Science Advances.
Why Cancer Risk Increases with Age
Let us recall that several years ago scientists came to the conclusion that ancient viruses are related to cancer, but they did not know what effect they had on the tumor. Now it has been found out that cancer cells use zombie viruses to change gene expression patterns, and this allows tumors to develop and progress. As the study showed, only one family of retroviruses can regulate up to 70 genes associated with cancer. Scientists cannot say how many such retroviruses are contained in human DNA.
After the virus was removed, cancer in mice became treatable. Photo source: spf-animals.ru
Scientists also suggest that as the human body ages, more and more zombie viruses awaken in it, as the natural defense weakens. Perhaps for this reason, the risk of developing cancer increases, as well as other health problems arise. If the scientists' findings are confirmed, this will improve the effectiveness of existing methods of treating cancer and may even lead to the development of methods for preventing cancer.
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Finally, we remind you that new, even more effective technologies for treating cancer are also on the way. For example, one of them is mRNA therapy, which has shown high efficiency even in the treatment of cancer in the last stages.