The Only Known Cancerless Animal

Posted on October 28, 2009  Comments (9)

Unlike any other mammal, naked mole rate communities consist of queens and workers more reminiscent of bees than rodents. Naked mole rats can live up to 30 years, which is exceptionally long for a small rodent. Despite large numbers of naked mole-rats under observation, there has never been a single recorded case of a mole rat contracting cancer, says Gorbunova. Adding to their mystery is the fact that mole rats appear to age very little until the very end of their lives.

The mole rat’s cells express p16, a gene that makes the cells “claustrophobic,” stopping the cells’ proliferation when too many of them crowd together, cutting off runaway growth before it can start. The effect of p16 is so pronounced that when researchers mutated the cells to induce a tumor, the cells’ growth barely changed, whereas regular mouse cells became fully cancerous.

“It’s very early to speculate about the implications, but if the effect of p16 can be simulated in humans we might have a way to halt cancer before it starts.” says Vera Gorbunova, associate professor of biology at the University of Rochester and lead investigator on the discovery.

In 2006, Gorbunova discovered that telomerase—an enzyme that can lengthen the lives of cells, but can also increase the rate of cancer—is highly active in small rodents, but not in large ones.

Until Gorbunova and Seluanov’s research, the prevailing wisdom had assumed that an animal that lived as long as we humans do needed to suppress telomerase activity to guard against cancer. Telomerase helps cells reproduce, and cancer is essentially runaway cellular reproduction, so an animal living for 70 years has a lot of chances for its cells to mutate into cancer, says Gorbunova. A mouse’s life expectancy is shortened by other factors in nature, such as predation, so it was thought the mouse could afford the slim cancer risk to benefit from telomerase’s ability to speed healing.

While the findings were a surprise, they revealed another question: What about small animals like the common grey squirrel that live for 24 years or more? With telomerase fully active over such a long period, why isn’t cancer rampant in these creatures?

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Gorbunova sought to answer that question, and in 2008 confirmed that small-bodied rodents with long lifespans had evolved a previously unknown anti-cancer mechanism that appears to be different from any anticancer mechanisms employed by humans or other large mammals.

At the time she was not able to identify just what the mechanism might be, saying: “We haven’t come across this anticancer mechanism before because it doesn’t exist in the two species most often used for cancer research: mice and humans. Mice are short-lived and humans are large-bodied. But this mechanism appears to exist only in small, long-lived animals.”

When Gorbunova and her team began specifically investigating mole rat cells, they were surprised at how difficult it was to grow the cells in the lab for study. The cells simply refused to replicate once a certain number of them occupied a space. Other cells, such as human cells, also cease replication when their populations become too dense, but the mole rat cells were reaching their limit much earlier than other animals’ cells.

“Since cancer is basically runaway cell replication, we realized that whatever was doing this was probably the same thing that prevented cancer from ever getting started in the mole rats,” says Gorbunova.

Like many animals, including humans, the mole rats have a gene called p27 that prevents cellular overcrowding, but the mole rats use another, earlier defense in gene p16. Cancer cells tend to find ways around p27, but mole rats have a double barrier that a cell must overcome before it can grow uncontrollably.

Full press release

9 Responses to “The Only Known Cancerless Animal”

  1. Sihastria
    October 29th, 2009 @ 5:39 am

    So if they could find a way to transfer the defensive system from the p16 gene to humans we would be cancer-proof right? But wouldn’t that interfere with the telomerase that helps us heal our wounds?
    How can they go around that? Seems like a double-edged sword.

  2. Weekend miscellany — The Endeavour
    October 30th, 2009 @ 11:49 pm

    […] The only animal that doesn’t get cancer […]

  3. dieren
    November 7th, 2009 @ 5:34 pm

    Pretty interesting.. I’m not sure if I want mole rat DNA strains to prevent cancer.

  4. Anonymous
    November 16th, 2009 @ 2:42 pm

    This is pretty cool! This should be a headline in Science-related newsletters in educational institutions. This study does not only awakens scientific consciousness on the study of simple organisms but gives further idea that simple creatures can have as many amazing characteristics that have not been discovered yet, but can be useful to human.

  5. Peggy
    November 23rd, 2009 @ 5:00 pm

    Unfortunately it’s likely to be much more complicated than the press release suggested (no big surprise there). Changing the expression of p16 in humans would likely change the expression of dozens of other proteins involved in the cell cycle. There has been a lot of study of p16 (also called Ink4a) in transgenic mice and in human and mouse cells that demonstrate the complexity of the cell cycle – increase the level of one component and the levels of the other factors can turn out to be either good or bad.

    If you read the abstract of the paper (rather than the press release), it’s clear that mole rat cells are regulating cell division in a different way than mouse and human cells. Transferring the same characteristics to humans would require a lot more engineering than just changing the expression pattern of p16.

    That’s not to say it couldn’t be done, just that it won’t be done until cell cycle regulation is much better understood!

  6. Adam Daly
    October 4th, 2010 @ 4:36 pm

    Wow what a diverse blog. From robots to cancer free animals, nice. I was just watching a video from the Ted conference, that covered foods one can eat that are anti-androgenic in nature Really interesting stuff. We may not be able to be immune to cancer just yet (like the naked mole rat) but it appears that there are foods one can eat to decrease chances of getting cancer.

  7. Cancer Cells in Blind Mole Rats ‘commit suicide’ » Curious Cat Science and Engineering Blog
    November 6th, 2012 @ 7:19 pm

    […] They’re also cancer-proof, which was found in 2011 to be down to a gene that stops cancerous cells from forming. The same team thought that two other cancer-proof mole rat species might have similar genes, but instead it turns out that they do develop cancerous cells — it’s just that those cells are programmed to destroy themselves if they become dangerous. […]

  8. Anonymous
    November 7th, 2012 @ 4:14 pm

    This is a remarkable creature this naked mole rat. Immune to cancer and doesn’t feel pain!? Sound like a superhero. I hope this research will eventually lead to a more effective cancer treatment.

  9. Cancer Rates Consistent Across Species Instead of Increasing Due to Body Mass » Curious Cat Science Blog
    October 12th, 2015 @ 7:30 am

    It would seem sensible to think cancer should be more prevalent in species with a huge number of cells, and thus more cells to become cancerous…

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