News / Health

    Gene Study Uncovers Origins of Many Common Cancers

    Lab officer cuts DNA fragment under UV light from an agarose gel for DNA sequencing as part of research to determine genetic mutation in a blood cancer patient, Singapore, file photo.
    Lab officer cuts DNA fragment under UV light from an agarose gel for DNA sequencing as part of research to determine genetic mutation in a blood cancer patient, Singapore, file photo.
    Reuters
    Researchers in Britain have set out the first comprehensive map of mutational processes behind the development of tumors — work that should in future lead to better ways to treat and prevent a wide range of cancers.
     
    In a study published in the journal Nature on Wednesday, researchers who analyzed more than 7,000 genomes, or genetic codes, of common forms of cancer uncovered 21 so-called "signatures" of processes that mutate DNA.
     
    "[This] is an important step to discovering the processes that drive cancer formation," said Serena Nik-Zainal of the Wellcome Trust Sanger Institute who worked on the research.
     
    "Through detailed analysis, we can start to use the overwhelming amounts of information buried deep in the DNA of cancers to our advantage in terms of understanding how and why cancers arise."
     
    All cancers are caused by mutations in DNA occurring in cells of the body during someone's lifetime.
     
    Scientists are clear about some things, such as that chemicals in tobacco smoke cause mutations in lung cells that lead to lung cancers, or that ultraviolet light triggers mutations in skin cells that lead to skin cancers.
     
    But they have yet to figure out the biological processes that cause mutations behind most common cancers.
     
    "We're beginning to know quite a lot about what the consequences of those mutations are. But actually we have a really rudimentary understanding of what is causing the mutations in the first place," said Mike Stratton, the Sanger Institute's director and the lead researcher on this study.
     
    "And after all, the things that are causing those mutations are the causes of cancer."
     
    The team analyzed the genetic codes of 7,042 cases of cancer in people from around the world, covering 30 different types of the disease, to see if they could find patterns, or signatures, of mutational processes.
     
    They discovered that all the cancers contained two or more signatures — a finding that shows the variety of processes that work together when a cancer develops.
     
    They also found that different cancers have different numbers of mutational processes. While two mutational processes underlie the development of ovarian cancer, there are six behind the development of liver cancer, the researchers said.
     
    And some signatures are found in multiple cancer types, while others are only found in one type. Out of the 30 cancers, 25 had signatures from mutational processes linked to aging.
     
    In a suggestion of what might be behind many common cancers, the team also discovered that a family of enzymes called APOBECs, known to mutate DNA, was linked to more than half of the cancer types studied.
     
    APOBECs can be activated when the body is responding to a viral infection. The researchers said it may be that the resulting “signatures” are collateral damage on the human genome caused by the enzymes acting to protect cells from viruses.
     
    Stratton described the results as like uncovering the "archeological traces" of the many mutational processes that lead to most cancers.
     
    "This compendium of mutational signatures and the consequent insights into the mutational processes underlying them has profound implications for the understanding of cancer."

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    by: Jonathan from: USA
    August 14, 2013 4:42 PM
    The headline, "Gene Study Uncovers Origins of Many Common Cancers," is completely untrue. The article mentions only one cancer cause: smoking, which was identified long ago without the need for genetic investigations.

    Lifestyle factors cause most cancers and focusing on genes is a red herring. It will not identify the actual cause. For example, the cause of breast cancer is chronic constriction, due to the perverse custom of wearing bras. This is explained at http://www.isisboston.com/assets/PDF-Files/Bras-and-Breast-Cancer.pdf

    The cause of colon cancer is the unnatural method of defecation used in western society. Humans were designed to squat for bodily functions. The sitting position results in incomplete emptying of the colon, leading to fecal stagnation, bacterial overgrowth, and inflammation. Chronic inflammation causes malignant mutations. This is explained at http://www.naturesplatform.com/health_benefits.html . Both breast cancer and colon cancer are confined to the "western" world or to countries that have adopted the above-mentioned western customs.
    In Response

    by: Jonathan from: usa
    August 15, 2013 12:13 PM
    They are present in the urban areas of the East, because the residents, wanting to appear "progressive", have adopted western toilets and western undergarments like bras. Genetics-based therapies include prophylactic mastectomies and heavy use of drugs. These treatments do not address the cause of the disease. Those profiting from the treatments strongly oppose research into the lifestyle causes.
    In Response

    by: Ramnarayan from: Florida, USA
    August 15, 2013 6:49 AM
    This is too simplistic view a out the etiology of colon and breast cancers. These two cancers are not just restricted to the western world, but have also been present in the East and other countries. However, the writter raises interesting scenarios. A detailed epidiomological study is needed before a strong correlation s established. Regardless, the cancer signatures hold promise for the diagnosis and therapy. In that sense, this study is very exciting.

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