They've also been nicknamed 'sand puppies.' Smithsonian's National Zoo/Flickr CC BY-NC-ND 2.0

There’s plenty more to naked mole-rats than their humorously phallic appearance. Neither a mole nor a rat, these saber-toothed sausages have remarkably long lifespans, living for up to 30 years – five times longer than what you’d expect for an animal of that size. Not only that, but the bratwursts-on-legs seem to be uniquely impervious to age-related diseases, most notably cancer. Or so we thought.

For the first time, cancer has been documented in this weird and wonderful species, in not one but two animals living in U.S. zoos. While these cases don’t call into question their cancer-fighting abilities, say the study authors, they do perhaps suggest that resistance in these animals may not be as broad as once thought.

Described in the journal Veterinary Pathology, the first rodent was a 22-year-old male born in Brookfield Zoo, Chicago that was taken to vets because of a lump under its right armpit. After surgically removing the mass and examining it in the lab, scientists could see clear evidence of abnormal cells showing signs of aberrant cell division. After staining the cells to look for particular cancer markers, the researchers were able to conclude that the tumor was likely a type of cancer called an adenocarcinoma, which probably had its origins in either mammary or salivary glands.

The second animal, a 20-year-old male from Washington’s National Zoological Park, had actually been suffering progressive weight loss and skin problems before the cancer was diagnosed and unfortunately had to be put down. Upon examination of the animal’s stomach, the team discovered a mass of abnormal cells which had their origins in the neuroendocrine system – the body’s nervous and hormonal systems. The researchers suspect that the mole-rat’s weight problems were probably related to the cancer.

The report is interesting because it tells us that, contrary to long-standing belief, naked mole-rats can actually succumb to cancer. That’s important, because these rodents were and still are considered valuable models for the study of cancer. For instance, scientists have already begun to reveal what appears to be the secret to their unique ability to stave off cancer.

A couple of years ago, researchers discovered that naked mole-rats produce an extra-large version of a sugar called hyaluronan, which appears to prevent cells from overcrowding and thus forming tumors. Interestingly, its synthesis is more robust in these animals compared with other mammals, and it’s also broken down less because the enzymes responsible for degrading it are less active in naked mole-rats. This allows the sugar to accumulate in their tissues to a greater extent than other animals, giving their skin its characteristic elasticity. Interestingly, that likely evolved as an adaptation to their burrowing lifestyle, helping them crawl around tight tunnels in Africa, but has then had the added bonus of increasing cancer-resistance. 

Main image credit: Naked Mole-Rat 20th Anniversary at the Smithsonian’s National Zoo, Smithsonian's National Zoo/Flickr CC BY-NC-ND 2.0

Image in text: No, that's not a penis with teeth. Credit: Naked mole-rat from Africa. Juha Ristolainen/Flickr CC BY-NC-ND 2.0

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