Nitric oxide shown to cause colon cancer

January 20, 2009 by Anne Trafton

(PhysOrg.com) -- Researchers long ago established a link between inflammation, cancer and the compound nitric oxide, which may be produced when the immune system responds to bacterial infections, including those of the colon. However, the exact nature of the relationship was unknown -- until now.

Scientists from MIT's Division of Comparative Medicine and Department of Biological Engineering have found that nitric oxide produced by inflammatory cells during bacterial infection can cause colon cells to become cancerous. The finding suggests that blocking the compound may help prevent or treat colon cancer, the third most common form of cancer in the United States.

The researchers, led by James Fox, director of the Division of Comparative Medicine (DCM), report their findings in the Jan. 19 online edition of the Proceedings of the National Academy of Sciences.

Many years ago it was discovered that gastrointestinal infection by H. pylori is often linked to cancer in humans; a related bacteria called H. hepaticus has similar effects in mice.

Nitric oxide is produced during the inflammatory response to such bacterial infection, but it has been unclear whether it was damaging cells or protecting them. By studying mice, the MIT team found that nitric oxide produced by different types of cells has different effects.

"Nitric oxide delivered by inflammatory cells, in particular, is important in causing changes in intestinal epithelial cells, setting the stage for cancer development," said Susan Erdman, principal research scientist in the Division of Comparative Medicine and lead author of the PNAS paper.

In mice infected with H. hepaticus, the researchers found that blocking an enzyme needed to produce nitric oxide reduced colon cancer rates. More work is needed to study the exact effects of nitric oxide and develop potential clinical therapies for colon cancer, Erdman said.

"Therapies will need to be targeted to inhibit the damaging effects of nitric oxide while preserving as many of the protective elements of nitric oxide as possible," she said.

"This study is a wonderful example of the value and final product that results from an interdisciplinary team effort," said Fox.

Provided by MIT

• deatopmg - Jan 20, 2009
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  how sure are they that it's NO and not superoxide or ozone, both of which are produced and cause inflammation
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• barakn - Jan 20, 2009
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  Didn't read the article, obviously.
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• E_L_Earnhardt - Jan 20, 2009
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  Inflammation = accelerated electron speed & spin = "Heat". hypertherapy causes cancer, hypOtherapy can CURE it! Rate of mitosis directly related to temp.!
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• JayDub - Jan 22, 2009
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  So should people not be taking suppliments that promote the production of NO? There are a lot of those out there right now. If the body is producing it naturally as a response to inflamation...
  I though NO had anti-cancer properties.
  I know there is NOS, Nitric Oxide Synthases too. Ugh, could someone please break it down for the "lay person"? Thanks.
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