Mice fed an experimental anti-inflammatory drug three days before exposure to space-like radiation developed half as many carcinomas as mice that did not get the compound, a finding that has implications for astronauts on long-duration missions, as well as people on Earth receiving radiation treatments for therapeutic reasons, new research shows.
The compound, which is derived from plant moss, belongs to a family of drugs called synthetic triterpenoids, which in addition to easing inflammation appear have powerful antioxidant properties.
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Synthetic triterpenoids already are in clinical trials and appear to be useful in treating kidney disease, diabetes, age-related macular degeneration, pulmonary diseases, Alzheimer's, Parkinson's and various cancers.
The idea to give irradiated mice food laced with a dose of the synthetic triterpenoid CDDO-Me stemmed from a previous series of experiments.
Researchers discovered that mice irradiated over several days developed more cancerous tumors than mice receiving a single hit of radiation, even though the total dosages were identical, Jerry Shaw, with the University of Texas Southwestern Medical Center in Dallas said at the American Society for Gravitational and Space Research conference in Orlando last week.
That got them wondering why.
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The mice had been genetically modified to be susceptible to either lung cancer or colon cancer -- the first and second leading causes of cancer deaths in the United States.
Cells in the lungs tend to be replaced only when damaged, while colon cells turn over about every seven days, giving researchers two different processes to study.
Splitting up the radiation dose had similar effects on both groups. So did varying the type of radiation.
"This suggested that there was something about the fractioned dose of radiation that was leading to more invasive cancers," Shaw said.