Logically, elephants should get cancer much more than humans do—elephants have 100 times more cells than we do and live just about as long, providing ample opportunity for cancer-causing mutations to occur. But in fact they have less cancer; an analysis of hundreds of zoo deaths found that only five percent of elephants die of cancer, whereas 11 to 25 percent of humans do, according to the New York Times. Scientists hypothesize that, in order to get so large and biologically complex, elephants’ bodes must have evolved a way to suppress cancer. But they weren’t sure quite how they kept the cancer at bay.
Now, two teams of scientists have figured out the gene that prevents elephants from getting cancer, according to a study published today in theJournal of the American Medical Association and another currently under review at eLife.
In both studies, the researchers turned to elephant genes. They analyzed the DNA of African and Asian elephants and discovered that both species had 20 copies of P53, a gene known to have tumor-suppressing qualities. The team from the University of Utah School of Medicine looked at the DNA of 60 smaller organisms, including humans, and found that most have only one copy of P53. The authors of the other study, led by researchers from the University of Chicago, analyzed the genes of elephants’ smaller ancestors, discovering that they contained fewer copies of P53. That implies that, as elephants evolved to be larger, their genetic code developed more copies of P53. When cancerous mutations occur, the genetic mutation causes them to quickly die, making them less likely to proliferate and form tumors.
The researchers are quick to point out that this discovery doesn’t answer all of scientists’ questions about P53—they still don’t know how it figures in to the genomes of other large mammals, like whales. And though researchers on the clinical side have already been studying P53 for a long time, using it in immunotherapy treatments to combat cancers that have sprung up in the body, other large and long-lived animals may have of their own ways of combatting cancer could be useful in humans. It’ll be decades before these discoveries become clinically useful, the researchers told Motherboard, but it’s not a bad idea to extrapolate some cancer-fighting tactics from other members of the animal kingdom.
source: popsci.com By Alexandra Ossola