Apart from their hairless appearance, naked mole rats are known for several distinguishing characteristics: They have an unusually long life span for a rodent, and they seem to be protected from developing cancer. Now, researchers have pinpointed a natural substance found between the rodents' tissues that may explain their cancer resistance.
Understanding how this substance, known as hyaluronan, protects naked mole rats from developing cancerous tumors could lead to novel cancer-prevention techniques for humans, said study lead author Vera Gorbunova, a professor in the department of biology at the University of Rochester in New York.
In animals, hyaluronan is a component of the extracellular matrix (the noncellular part of tissue) and is known to hold cells and tissues together. The substance also acts as a signal to control the growth of certain cells, said Andrei Seluanov, an assistant professor in the department of biology at the University of Rochester, and co-author of the new study.
The researchers studied tissue cultures from naked mole rats and found these small, subterranean rodents produce a unique, high-molecular-mass form of hyaluronan, which they referred to as HMW-HA. When this substance was removed, Gorbunova and her colleagues found that naked mole rat cells became susceptible to tumor growth, suggesting HMW-HA plays an important role in the rodents' resistance to cancer. [10 Amazing Things You Didn't Know About Animals]
"This is unique to this species, so it's pretty amazing," Seluanov said. "We were able to focus on the anti-cancer mechanism in naked mole rats."
Hyaluronan also keeps tissues flexible, he added, something that would be beneficial for the burrowing rodents.
"Naked mole rats need good elasticity in their skin, because they don't have any fur," Seluanov said. "When they move through their tunnels, it's important that they do not rupture their skin."
The demands of their subterranean lifestyle may explain why naked mole rats developed higher levels of hyaluronan in their skin in the first place, the researchers said.
"What excites me is that this is just one component of a whole mosaic of strange characteristics that these animals have produced due to extreme adaptations to living underground," said Chris Faulkes, a molecular ecology researcher at the Queen Mary University of London, who was not involved with the study.
In this way, natural selection may have influenced the cell biology of naked mole rats, he added.
"This high-molecular-mass hyaluronan may have been produced to give naked mole rats highly elastic skin so they don't get stuck in burrows, and it's almost a side consequence that it seems to be useful in preventing cancer as well," Faulkes said.
Whereas humans also produce hyaluronan naturally, it is in much smaller quantities, and the physical properties are different, according to the researchers. Still, determining the anti-cancer mechanism in naked mole rats could have far-reaching clinical applications for humans.
"By looking at this completely weird and unusual organism, we can find some novel mechanisms that apply across mammals," Faulkes said. "Understanding some of these amazing things could have broad applicability for human health."
Because of its elastic properties, hyaluronan injections are already used in clinical settings, most notably in dermatology and as a pain reliever for people with arthritis in knee joints, Seluanov explained. So far, no significant side effects have been reported, the researchers said.
In the future, the researchers plan to investigate whether HMW-HA can effectively protect human cells from cancer.
"We are very optimistic that the anticancer mechanism we found in the naked mole rat can be translated to humans," Gorbunova said.
The detailed results of the study were published online June 19 in the journal Nature.
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