Why Don't Elephants Get Cancer?

Elephants' Extraordinary Cancer-Protective Mechanism: The Role of TP53 Gene

For many years, scientists have been intrigued by the fact that elephants are much less likely to get cancer compared to humans and other animals. Despite having 100 times more cells than humans, elephants have a remarkably low incidence of cancer, with a rate of only 5 percent compared to humans' 25 percent. This phenomenon, known as the Peto Paradox, challenges the accepted notion that cancer risk increases with increasing body size in animals.

Recent research has uncovered the reason for elephants' advanced cancer-protective mechanism. The study published in October revealed that elephants have extra genes in their genetic structure, which play a crucial role in stopping the growth of tumors. The focus of the study was on the TP53 gene, a cancer-critical tumor suppressor gene that is found in humans and other animals.

While humans have two copies of the TP53 gene inherited from the mother and father, elephants were discovered to have 40 copies of this gene. The p53 gene's primary function is to prevent tumor growth by stopping cell division and initiating mechanisms to repair damage to genetic information in cells. If the damage is beyond repair, p53 causes the cell to disappear through programmed cell death called apoptosis.

In more than 50 percent of human cancers, the p53 gene is mutated, rendering it unable to function correctly. To be effective, both copies of the TP53 gene must be intact, inherited from the mother and father. If one of the two copies is damaged, as a result of a mutation, p53 cannot fulfill its function. This syndrome is known as Li Fraumeni Syndrome, and people with this condition have a very high risk of developing cancer.

To test the TP53 gene's role in elephants' cancer resistance, researchers exposed blood samples taken from healthy people, people with Li Fraumeni Syndrome, and elephants to radiation to determine the death rate in cells. As expected, the most cell death was observed in blood cells taken from elephants with 14.6 percent, whereas 7.2 percent of cells in healthy people and 2.7 percent of cells in people with Li Fraumeni Syndrome died. These results demonstrated that elephants eliminate their damaged cells before they become cancerous, thanks to the extra TP53 genes they have.

In conclusion, the study sheds light on the mystery behind elephants' low cancer rates and their remarkable cancer-protective mechanism. The TP53 gene's critical role in preventing tumor growth and eliminating damaged cells highlights the importance of studying elephant biology to understand cancer's fundamental biology in humans and other animals.