The naked mole rat is a longevity enigma wrapped in a mystery wrapped in a gross, wrinkly, loose skin bag. Research has well established that the little African critter has a unique ability to live much longer than its rodent peers and can naturally ward off cancer. But a new study published today in Biology Letters comparing the genetics of the naked mole rat to other mammals—even its closest relatives—shows just how unique this ability really is.
For years, scientists have studied naked mole rats in captivity in an attempt to gain better understanding of their unique social structures. But close observation revealed something unexpected: naked mole rats live a really long time without getting cancer.
Naked mole rats can live as long as 32 years—ten times longer than a mouse, and five times longer than science would predict given its body size, according to the study. And not only do they live to a ripe old age, naked mole rats manage to do so without ever getting getting cancer, or showing much sign of aging (other than the fact that they kind of always look like an old man).
"They live into this remarkable old age, up to 32 years, yet they maintain a really healthy phenotype until they are really, really old," Chris Faulkes, an evolutionary ecologist at Queen Mary University of London and lead author of the study, told me over the phone.
Research in 2013 showed that the naked mole rat's fountain of youth could at least partly be attributed to its HAS2 gene, which has a mutation that causes it to produce large amounts of high molecular mass hyaluronan in the rat's skin. Hyaluronon is a kind of gooey, sugary molecule that prevent tumors from forming when in this high-mass state, Faulkes said.
After seeing this research, Faulkes and his colleagues wanted to see whether the naked mole rat's closest relatives (or any other mammals, for that matter) had similar mutations in their HAS2 genes. They compared HAS2 gene sequences in dozens of mammals, from rats to humans.
"I expected that some of the other African mole rats might have the same gene sequence but, in fact, they don't," Faulkes said.
And while the researchers did find a host of other kinds of mutations in the HAS2 gene in different species, they don't yet know what those mutations do, or whether they too might help other species ward off cancer and live longer.
There's actually not a ton of data on the longevity of other kinds of mole rats and small rodent, Faulkes said, so he's itching to do more tests to see what these mutations do and whether or not they have a similar effect. In particular, Faulkes mentioned that the elephant shrew had the most mutations out of all of the animals they sequenced, and he's curious to find out what those substitutions do.
The long list of newly discovered mutations could mean there is not just one way of genetic cancer-proofing—as seen in the naked mole rat—but multiple gene mutations that could help prevent tumor growth in mammals. It could one day open the door for new cancer treatments in humans, too.
"If research uncovers new mechanisms whereby tumor formation can be resisted, then I'm sure drug companies are looking really closely at possible ways that you might exploit that," Faulkes said. "It potentially opens up a whole new way of looking at that kind of tumor formation, so I don't think it's a big stretch of the imagination to say these could have some impact in understanding human cancers and working out a new treatment."