Scientists investigated why elephants have a high resistance against cancer and discovered the genetic mechanism that enables these animals to fight tumor growth. The findings of their study could help in the development of cancer treatment in humans, according to Live Science.
In the first part of the study, the researchers looked at 14 years worth of necropsy data from the San Diego Zoo. They found that the cancer risk - which usually increases with body size and longer life span - for elephants was low; only 4.8 percent of elephants die from cancer. On the other hand, 11 to 25 percent of humans die from cancer.
Next, the scientists investigated how the TP53 gene protected against cancer. TP53 is a gene that suppresses tumor growth. In most cases of human cancers, this gene is mutated, leading to increased cell reproduction and genome mutations.
Humans usually get a pair of TP53 gene copies - one copy from each parent. Sometimes, only one copy works, a case known as the Li-Fraumeni syndrome. People with this syndrome are 90 percent more likely to develop cancer compared to those who don't.
Elephants, the researchers found, receive 20 copies of the TP53 gene from each parent.
"We think that making more TP53 is nature's way of keeping this species alive," Dr. Joshua Schiffman, lead study author and pediatric oncologist at the Huntsman Cancer Institute, University of Utah, said in a press release.
The researchers took blood samples from people with Li-Fraumeni syndrome, people without Li-Fraumeni syndrome and elephants. The blood samples were then exposed to radiation.
Normally, TP53 would attack and kill cells that are exposed to radiation. After radiation exposure, the researchers found that in people with Li-Fraumeni syndrome, only 2.7 percent of the cells died, while in those who did not have the syndrome, 7.2 percent of the cells died. In elephants, 14.6 percent of the cells died - twice as much as those in healthy humans.
"These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression," the study authors wrote.
The study was published in the Oct. 8 online issue of the journal JAMA.
