Researchers discovered that in mouse models, low doses of radiation increase p53 mutations in cells, which is a genetic change associated with cancer. To combat this negative effect, the investigators found that giving mice an antioxidant prior to radiation stimulated proliferation of healthy cells that replaced the p53-mutant cells.
For this study, published in Cell Stem Cell, the scientists tracked mouse cells during low-dose ionizing radiation (LDIR) and discovered that this procedure promotes cell differentiation—the process of a cell changing from one cell type to another—and mitigates cell proliferation in normal cells in the esophagus. However, p53-mutant cells are immune to LDIR and outcompete normal cells. It was found that LDIR causes redox stress but doesn't activate the DNA repair pathway, giving p53-mutant cells an advantage over healthy cells.
This effect was reversed if an antioxidant was given to mice prior to receiving LDIR. Antioxidant plus radiation allowed healthy cells to proliferate and caused p53-mutant cells to differentiate, giving the healthy cells a competitive advantage over the mutated cells.
Despite this evidence, antioxidants are not a solution for preventing cancer. One of the study authors, Kasumi Murai, PhD, Senior Staff Scientist at the Wellcome Trust Sanger Institute, explained, "Giving mice an antioxidant before exposing them to low doses of radiation gave healthy cells the extra boost needed to fight against the mutant cells in the esophagus and make them disappear. However, we don't know the effect this therapy would have in other tissues—it could help cancer-capable cells elsewhere become stronger. What we do know is that long term use of antioxidants alone is not effective in preventing cancer in people, according to other studies."
Lead study author, Philip H. Jones, PhD, of the Wellcome Trust Sanger Institute, concluded, "Medical imaging procedures using radiation, such as CT scans and x-rays, have a very low level of risk—so low that it's hard to measure. This research is helping us understand more about the effects of low doses of radiation and the risks it may carry. More research is needed to understand the effects in people."
For More Information
Fernandez-Antoran D, Piedrafita G, Murai K, et al (2019). Outcompeting p53-mutant cells in the normal esophagus by redox manipulation. Cell Stem Cell. [Epub ahead of print] DOI:10.1016/j.stem.2019.06.011
Image Courtesy of the Food Revolution Network