How Tumours Survive

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Increased levels of certain antioxidants may actually help cancers grow.
Posted On: March 06, 2015
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The Canadian Cancer Society recommends eating unprocessed and fresh foods that are rich in antioxidants rather than taking high-dose antioxidant supplements

The role of antioxidants in cancer is highly controversial. Some studies show that an antioxidant-rich diet is important for health, while others indicate that antioxidants taken in pill form can be harmful. New findings from PM Cancer Centre Senior Scientist Dr. Tak Mak add to the controversy by revealing that tumour growth may be enhanced by the presence of high levels of antioxidants.

Dr. Mak explains, "When cells grow and divide, they produce harmful oxidative byproducts. Cancer cells, which grow very quickly and therefore produce high levels of harmful oxidative byproducts, may increase the production of antioxidants to support their survival."
In a recent article published in the journal Cancer Cell, Dr. Mak and his team revealed that turning off two key antioxidant pathways in an experimental cancer model delays the development and reduces the severity of a variety of cancers.

The two pathways that the researchers targeted were glutathione (GSH) and theoredoxin (TXN). Drugs capable of turning these pathways off are currently being used to treat rheumatoid arthritis. Because the drugs are approved for use in humans, they could help to fast track these findings towards new, effective treatments for cancer patients.

This work was supported by the Natural Sciences and Engineering Council of Canada, the German Research Foundation, the ATTRACT program of the Luxembourg National Research Fund, the Canadian Institutes of Health Research and the Princess Margaret Cancer Foundation. T Mak holds a Tier 1 Canada Research Chair in Inflammation Responses and Traumatic Injury.

Glutathione and thioredoxin antioxidant pathways synergize to drive cancer initiation and progression. Harris IS, Treloar AE, Inoue S, Sasaki M, Gorrini C, Lee KC, Yung KY, Brenner D, Knobbe-Thomsen CB, Cox MA, Elia A, Berger T, Cescon DW, Adeoye A, Brüstle A, Molyneux SD, Mason JM, Li WY, Yamamoto K, Wakeham A, Berman HK, Khokha R, Done SJ, Kavanagh TJ, Lam CW, Mak TW.Cancer Cell. 2015 January 21. [Pubmed abstract]