Why are some species of animals more prone to developing cancers than others? This question has intrigued scientists for decades, especially since in the 1970s a British epidemiologist enunciated the so-called “Peto paradox” , in honor of his name. According to him, if all living cells have the same probability of developing a tumor, it should be the largest and longest-lived animals that suffer a higher incidence of the disease.
However, nature seems to go other ways, as animals such as elephants and whales develop fewer cancers than other smaller species. Elephants, in particular, can survive for more than 60 years: “Animals with such a long life and with so many cells should suffer from many more cancers. But if it were, they would have become extinct ”, explains Joshua Schiffman, from the Huntsman Cancer Institute (Utah, USA), and one of the authors of the latest study that sheds light on the Peto paradox.
Using data from the Encyclopedia of Elephants, which collects the births and deaths of all captive elephants in the world, the researchers concluded that less than 5% of these animals die of cancer, a very small number. if compared to other animals such as wild dogs (8%) or humans (25%).
The answer is in the genes
The key, according to the results of this work published in the Journal of the American Medical Association , could be in the genes. And it is that the African elephant genome contains 40 copies of the TP53 gene, which codes for a protein known to be one of the most important mechanisms in the body to prevent cancer. Specifically, the protein prevents cancer cells from dividing until they are repaired, or it drives them to suicide.
In contrast, humans have only two copies of the TP53 gene, as does the Cape daman, a curious mammal that has been considered by some zoologists to be the closest living relative of elephants. The researchers suggest that the gene was probably accidentally duplicated several times in the ancestors of elephants.
Schiffman’s team will dedicate their future research to looking for ways to make human cells more like those of elephants , for example by inserting additional copies of the gene, or by identifying compounds that duplicate the effects of these copies.
