A research team peering into the relatively underexplored “junk” DNA of mammals has found more clues as to elephants’ extraordinary ability to evade cancer – and determined that the genes responsible for mitigating damage in elephant cells can also be found in humans.
Most of the world’s mammals are prone to cancer, but elephants are strangely resistant. They’re not completely immune, but compared to humans, they get it surprisingly rarely – especially considering that they have 100 times the number of cells that humans do.
Cancer occurs when a cell randomly mutates during division, so the fact that only around 1 in 20 elephants develops cancer, compared to 1 in 5 humans, is extremely curious.
Researchers had been trying to figure out why this was the case for decades, but it was only a few years ago that a team of researchers narrowed this incredible trait down to an overabundance of a gene called p53, which suppresses tumours. African elephants have 40 copies of p53. Humans have just one.
But now a team of researchers at the University of Utah has found more clues as to how it occurs, and it’s not just down to p53.
They studied what had been known for several decades since the 1960s as “junk DNA” – DNA that does not code for proteins. That doesn’t make it useless, however – recent studies have found that it performs other functions, such as being able to control when and where genes are expressed.
“People used to call the noncoding regions ‘junk DNA’, but I see it as a jungle that has not been explored,” said neurobiologist Christopher Gregg from the University of Utah.
“We are exploring the noncoding regions to try to discover new parts of the genome that might control different diseases.”
The team searched the parts of the elephant genome that are common to all vertebrates, but specifically evolved more rapidly in elephants. They were scanning these regions for elements that help resist mutation – and therefore cancer.
They identified three genes in the elephants’ DNA – FANCL, VRK2 and BCL11A – after exposing the DNA to gamma radiation and observing how it responded to damage. These genes in particular are involved in DNA repair that guards against mutations – and they’re strongly associated with elephant accelerations.