Research ArticleCancer

Antioxidants Accelerate Lung Cancer Progression in Mice

Science Translational Medicine  29 Jan 2014:
Vol. 6, Issue 221, pp. 221ra15
DOI: 10.1126/scitranslmed.3007653

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The Dark Side of Antioxidants

Antioxidants, or chemical compounds that prevent oxidation of other molecules, are widely marketed as dietary supplements with a variety of health claims. One particular characteristic that was frequently attributed to antioxidants is an ability to decrease the risk of cancer. However, a number of studies have shed doubt on this claim in recent years, as emerging evidence has suggested that antioxidants may actually increase the risk of some forms of cancer.

Now, a study by Sayin and coauthors sheds new light on this issue and suggests that antioxidants may have a particularly detrimental effect in lung cancer development. When mice carrying mutations that increase their risk of lung cancer were treated with antioxidants, their early precancerous lesions progressed more quickly, and the mice developed more tumors and at more advanced stages. The antioxidants did reduce oxidative stress and DNA damage as expected, but at the same time, they also reduced the expression of p53, a key tumor suppressor protein.

This work was done in cells and in mice, but the authors took care to make it as relevant to humans as possible. Thus, the mice were treated with types and doses of antioxidants (vitamin E and acetylcysteine) that healthy humans use, and the results were confirmed in human lung cancer cell lines. Although the current study does not show what would happen to wild-type mice or healthy people using antioxidants, it provides evidence for a procarcinogenic role of antioxidants in people who are already at a higher risk of cancer, such as smokers.