Research has shown that <5% of elephants succumb to cancer. This is remarkable as elephants are massive, meaning they have more cells to replicate on a regular basis than humans. One would think having so many cells would increase the risk of these cells dividing improperly, especially considering that captive elephants can live for about 70 years.
It has been known for several years that elephants have 20 copies of the gene for p53. This is a gene responsible for detecting and killing cells with misfolded DNA, thereby avoiding the development of cancer. Sadly, we only have one copy of this gene.
New research published in Cell Reports, provides even more clues to cancer resistance in elephants. It turns out that elephant ancestors re-animated a pseudogene called leukemia inhibitory factor 6 (LIF6), which may have allowed them to evolve larger body sizes while avoiding the corresponding increased risk for cancer development. In response to p53, LIF6 functions to kill cells with damaged DNA.
Researchers are now hoping to learn how we might be able to re-activate similar anti-cancer genes in other animals, and perhaps even humans someday.
Vazquez JM, Sulak M, Chigurupati S, Lynch VJ. A Zombie LIF Gene in Elephants Is Upregulated by TP53 to Induce Apoptosis in Response to DNA Damage. Cell Reports. 24 (7): 1765, 2018. DOI: 10.1016/j.celrep.2018.07.042