New Research Sheds Light on Tumor Formation

By Sheril Kirshenbaum | November 1, 2010 10:14 am

journal.pone.0012900.g001The sea turtle to the left has fibropapillomatosis, a tumor-forming disease linked to a herpes virus. While these tumors can appear grotesque, not all are malignant. Fibropapillomatosis has been around since the 1980s, but the cause has been unknown. A new paper in PLoS ONE by Van Houtan, Hargrove, and Balazs analyzed clusters of the virus in locations with high nutrient runoff. And here’s where the story gets interesting…

The authors discovered a relationship between eutrophication (excess nitrogen), an invasive species of algae, sea turtles, and the disease. It goes like this:

  1. The invasive algae stores excess nutrients in a particular amino acid
  2. Turtles eat that algae
  3. The metabolized amino acid promotes the herpes virus infection and, in turn, tumor formation

So it turns out that the root cause of the whole chain of events–leading to the large tumors we’re observing in sea turtles–is not the result of one of the usual suspects (i.e. carcinogens such as PCBs or 3-Nitrobenzanthrone).

When I spoke to lead author Kyle Van Houtan, he explained, “To me what is really fascinating about the whole argument is how it all begins with simple nitrogen [inputs from runoff] and how that travels through the physical watershed, the ecosystem, and ends up promoting tumors.”

The paper identifies the amino acid arginine as being involved in this process and, coincidentally, clinical trials for cancer drugs for human liver cancers are specifically targeting and destroying arginine. So as Van Houten points out, “There is perhaps more to this than simply sea turtle tumors. After all, 15-20% of human cancers are viral in origin.” In other words, understanding the cause of tumors in sea turtles may help researchers understand why they form in our species too.

CATEGORIZED UNDER: Marine Science, Media and Science

Comments (6)

  1. Douglas Fairburn

    That’s interesting; if they ever do find a cure for cancer it would be like finding the secret to the fountain of youth as I believe I heard once that cancer in one form or another is the cause of most cellular breakdown.

  2. Kelvin S

    this research is truly an “Intersection” piece, lots of things coming together. Shows we need to work together and collaborate between departments and disciplines. Does this happen is white lab coat geeks don’t talk to binocular-wielding bird nerds?

  3. Matt B

    “That’s interesting; if they ever do find a cure for cancer it would be like finding the secret to the fountain of youth as I believe I heard once that cancer in one form or another is the cause of most cellular breakdown.”

    I’m no biologist, and that could very well be true, but my understanding was that some cancers are the result of normal cellular breakdown, and not the cause. Specifically, during DNA transcription/replication, occasionally some amino acid pairings get messed up by the transcription enzymes, leading to incorrect/faulty codons. To rectify this, our DNA contains long chains of amino acids that essentially ‘don’t code’ for anything: they’re sort of like spare parts that can be swapped in by another enzyme when the first enzyme mucks up the pairings.

    Since our cells’ DNA is pretty much continuously replicating, those spare parts eventually start to run out. When they do, any further transcription errors that crop up don’t have replacements, and we end up just trying to live with them. These errors can cause all kinds of problems, including cancer. In some sense, this seems like it would explain why some cancers have a higher incidence rate among elderly people.

  4. -during DNA transcription/replication, occasionally some amino acid pairings get messed up by the transcription enzymes
    -our DNA contains long chains of amino acids

    You mean nucleotides, not amino acids.

  5. The relationship between eutrophication (excess nitrogen), invasive species of algae Hypnea musciformis and Ulva fasciata , sea turtles, and the disease will certainly open the door to understand the complete process of tumor formation and its treatment. This discovery also shows the important link between the foods and diseases. This is an important discovery. Best wishes to all respected scientists for the future Nobel Prize.

  6. Max Klein

    @Matt B “I’m no biologist”

    Damn right you’re not. Points to Wavefunction on his corrections.

    Most of your DNA cannot recombine at all, much less in the way that you describe, aside from a few fun exceptions like your antibody coding genes. Rather, there is simply a very low rate of errors durring replication. Your DNA is copied almost perfectly, and you get something like 3 errors out of 3 billion base pairs. Also, since most of your DNA is stuff like simple repeats and transposons, which do not (as far as folks have been able to tell) play a role in the survival of any given individual, most of these errors won’t even cause a ripple.

    However, after ~50 divisions those errors start to pile up, and the chances of something going wrong start to rise exponentially. If something goes wrong enough to change the cell’s behavior, but not wrong enough to actually kill the cell, you potentially end up with a malignant cancer.

    In terms of running out of spare parts, the only thing you have in your DNA that even vaguely fits that description are the telomeres, which do get shorter with every division in most of your cells. However, the telomeres act as a kind of fuse, causing the cell to die once it’s gone through enough divisions, helping to prevent, not cause, the kind of cancer-causing events I described above.

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About Sheril Kirshenbaum

Sheril Kirshenbaum is a research scientist with the Webber Energy Group at the University of Texas at Austin's Center for International Energy and Environmental Policy where she works on projects to enhance public understanding of energy issues as they relate to food, oceans, and culture. She is involved in conservation initiatives across levels of government, working to improve communication between scientists, policymakers, and the public. Sheril is the author of The Science of Kissing, which explores one of humanity's fondest pastimes. She also co-authored Unscientific America: How Scientific Illiteracy Threatens Our Future with Chris Mooney, chosen by Library Journal as one of the Best Sci-Tech Books of 2009 and named by President Obama's science advisor John Holdren as his top recommended read. Sheril contributes to popular publications including Newsweek, The Washington Post, Discover Magazine, and The Nation, frequently covering topics that bridge science and society from climate change to genetically modified foods. Her writing is featured in the anthology The Best American Science Writing 2010. In 2006 Sheril served as a legislative Knauss science fellow on Capitol Hill with Senator Bill Nelson (D-FL) where she was involved in energy, climate, and ocean policy. She also has experience working on pop radio and her work has been published in Science, Fisheries Bulletin, Oecologia, and Issues in Science and Technology. In 2007, she helped to found Science Debate; an initiative encouraging candidates to debate science research and innovation issues on the campaign trail. Previously, Sheril was a research associate at Duke University's Nicholas School of the Environment and has served as a Fellow with the Center for Biodiversity and Conservation at the American Museum of Natural History and as a Howard Hughes Research Fellow. She has contributed reports to The Nature Conservancy and provided assistance on international protected area projects. Sheril serves as a science advisor to NPR's Science Friday and its nonprofit partner, Science Friday Initiative. She also serves on the program committee for the annual meeting of the American Association for the Advancement of Science (AAAS). She speaks regularly around the country to audiences at universities, federal agencies, and museums and has been a guest on such programs as The Today Show and The Daily Rundown on MSNBC. Sheril is a graduate of Tufts University and holds two masters of science degrees in marine biology and marine policy from the University of Maine. She co-hosts The Intersection on Discover blogs with Chris Mooney and has contributed to DeSmogBlog, Talking Science, Wired Science and Seed. She was born in Suffern, New York and is also a musician. Sheril lives in Austin, Texas with her husband David Lowry. Interested in booking Sheril Kirshenbaum to speak at your next event? Contact Hachette Speakers Bureau 866.376.6591 info@hachettespeakersbureau.com For more information, visit her website or email Sheril at srkirshenbaum@yahoo.com.

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