Assistant to the "defenders of the genome"
Scientists have learned the secret of protecting elephants from cancer
Cell division, or mitosis, is a natural part of the life cycle of any cell, while daughter cells must receive exact copies of the maternal DNA in order to continue performing its functions. However, errors are not alien to anything alive, and even failures can creep into the DNA, which can lead to the appearance of a cancerous tumor.
Fortunately, most of these errors are quickly corrected by the cell itself, but this process of "genetic correction" strongly depends on many factors. Age, the level of stress experienced or the quality of nutrition — all this can lead to the preservation of errors in our genes.
However, it seems that elephants have learned to minimize the impact of their age on the risk of cancer. Although these huge animals are not inferior to humans in terms of life span, only five percent of elephants die from cancer, while in some human populations this figure reaches 25 percent. Scientists have found that the high resistance of elephants to cancer may be due to the presence of 20 copies of the p53 gene — the "keeper of the genome" — compared with a single copy found in other mammals.
The p53 protein plays a key role in regulating DNA repair mechanisms and suppresses uncontrolled cell growth. It is activated when DNA is damaged, and helps to stop copying DNA and start correcting it. When cell division is completed, p53 is inactivated by another protein, ubiquitin ligase MDM2, which triggers the destruction of p53. The interaction of these two proteins is an important element of any cell division, as well as the processes of restoration or final destruction of damaged cells.
Curiously, in elephants, 20 copies of the p53 gene are only called copies, although in fact they are slightly different from each other, and as a result, many similar proteins can work simultaneously in the animal's body. Even if some mistake in the DNA is missed by one molecule, others will be able to detect it, and in some cases changes in the structure of the p53 gene itself lead to the fact that the protein is not inactivated by ubiquitin ligase MDM2 and continues to work even after the end of cell division.
Perhaps, using the data obtained, scientists will be able to artificially start the preservation of the activity of p53 proteins in the body of people with a tendency to cancer, which will allow their cells to prevent a fatal mistake in the copied DNA.
The study is published in the journal Molecular Biology and Evolution (Padariya et al., The Elephant Evolved p53 Isoforms that Escape MDM2-Mediated Repression and Cancer).
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