Why elephants do not get cancer? Scientists have learned their secret
The researchers estimate that 17 percent. humans suffer from cancer, but among elephants this rate is as low as 5 percent., despite the fact that these animals have a much higher body weight, and thus more cells in which mutations can occur, which in turn can initiate cancer.
Scientists have wondered for years why elephants so rarely develop cancer. Humans, like other animals, have one copy of the suppressor gene p53. This gene controls the division of comórec, but it also recognizes DNA damage, whichóre may initiate cancer. When it recognizes defective comórki leads to their death.
A few years ago, researchers discovered that elephants have 20 copies of the p53 gene. This makes their comórk cells are much more sensitive to DNA damage and more quickly lead to the death of damaged comórek. Now researchers from the University of Chicago at the „Cell Reports” They described the second element of this process – an anti-cancer gene, whichóry researchers called the „zombie gene”.
– Genes duplicate all the time. Sometimes they make mistakes, creating non-functional versions known as pseudogenes. These are often called dead genes – said Vincent Lynch of the University of Chicago, head of theówny author of the publication.
While studying p53 in elephants, Lynch and colleagues found a former pseudogene called leukemia inhibitory factor 6 (LIF6), whichóry in some wayób has developed new functions. Activated by p53, it responds to DNA damage by killing defective comórki. The LIF6 gene produces a protein thatóre fairly quickly transferred to the mitochondriaów, headów of a common source ofódgs of comórki and stops their work, causing the death of the defective comórki.
– This dead gene powróciliated to life. Hence „zombie gene”. When activated by damaged DNA, it kills a cell very quicklyórka. This is beneficial because it acts in response to genetic mistakes made in DNA repair. Getting rid of such a comórki can prevent póof cancer – explained Lynch.
Elephants have eight geneóin LIF, but only LIF6 is known to be functional. – We can use the tricks of evolution to sprób to find out when this dead gene znóin began to function – stated Lynch. Researchers, based on the fossil record, concluded that this happened around 25-30 millionów years ago. This complementary method of tumor suppressionów may have been a key element in enabling tremendous growth, whichóry ultimately led to the creation of wspómodern elephants.
In the animal world, having large sizeów carries benefits. Small animals, such as mice, hogsórks or marmots, are devoured headównie by these larger. – If you’re huge, like an elephant or a whale, no one will mess with you,” Lynch pointed out.
But there are also downsides to such a situation. Larger animals have significantly more comórek and live longer, which means they have more time and opportunity to accumulate cancer-causing mutations. When the cellórks divide, there may be a mistakeóIn the Andes, and their repair process may simply not be up to the task.
– Large, long-lived animals, they must have developed robust mechanisms to suppress or eliminate comórks of cancer. These mechanisms allow them to live so long and reach considerable size – emphasized by Juan Manuel Vazquez, et alóLynch and co-workersórouter of publications.
Large animals are therefore more likely to developój comótumor rec. This can róalso happen on a smaller scale. The same is true in humans. Taller humans have a slightly higher incidence of several types ofóin cancerów than those of average height.
As the study authors point out, LIF6 has been „animated”, before there was even a need to maintain a larger body. This helped the development of large animals. However, the exact sposób, how LIF6 induces apoptosis (programmed cell deathórek), remains unclear. This will be the subject of further research.