Astronauts on long-duration space flights are exposed to higher levels and different types of radiation than are found on Earth. This radiation exposure can damage genetic material, DNA, and lead to cancer. However, certain diets high in n-3 fatty acids (fish oil) are thought to eliminate some of the DNA damage and prevent the onset of cancer. Through human and animal studies, Dr. Joanne Lupton is exploring whether diets high in dietary fiber and fish oil can reduce an astronaut’s potential risk for colon cancer.
Overview
Nutritional Countermeasures to Radiation Exposure
Principal Investigator:
Joanne R. Lupton, Ph.D.
Organization:
Texas A&M University
Technical Summary
Original Aims:
The overall goal of this research program was to develop nutrition countermeasures to radiation-induced colon tumorigenesis, using male Sprague Dawley rats as a model system. Superimposed on the background of irradiation with Fe-ions or no irradiation was the injection of a known colon specific carcinogen, azoxymethane (AOM) in order to simulate the potential exposure to environmental contaminants. The diet interventions tested were combinations of a lipid component (fish oil vs corn oil) and a fiber component (pectin vs cellulose). At the end of the three-year period, we anticipated knowing:
The overall goal of this research program was to develop nutrition countermeasures to radiation-induced colon tumorigenesis, using male Sprague Dawley rats as a model system. Superimposed on the background of irradiation with Fe-ions or no irradiation was the injection of a known colon specific carcinogen, azoxymethane (AOM) in order to simulate the potential exposure to environmental contaminants. The diet interventions tested were combinations of a lipid component (fish oil vs corn oil) and a fiber component (pectin vs cellulose). At the end of the three-year period, we anticipated knowing:
- if radiation exposure synergistically enhances colon tumor induction by AOM;
- which diet combination(s) are protective against colon cancer and if this effect is due to less DNA damage, greater removal of DNA-adducted cells by apoptosis or greater repair of DNA-adducted cells;
- if short-term studies (e.g. initiation or aberrant crypt formation) are predictive of later tumor development, and;
- if noninvasive technology can be used to detect specific mRNAs that are predictive for radiation exposure and/or response to that exposure, which would have later application to humans.
Key Findings:
The preliminary project results demonstrated that our selected radiation dose and sampling times were appropriate for the proposed experimental design. We discovered that prior exposure to radiation before exposure to a chemical carcinogen increased the severity of the preneoplastic lesions formed during colon tumorigenesis. Expression of genes associated with response to carcinogen exposure as well as control of cell cycle kinetics, is influenced by radiation exposure above and beyond that observed with the chemical carcinogen. The dietary manipulations demonstrate that fermentable fiber and n-3 fatty acids:
- influence the redox state of colonocytes in irradiated rats and alter the redox response to subsequent carcinogen exposure;
- affect the level of oxidative adducts present in DNA after carcinogen exposure;
- are able to reduce the formation of preneoplastic lesions of colon cancer through changes in cell cytokinetics regulated by altered gene expression, and;
- reduced the incidence of colon tumor incidence.
Impact of Findings on Project Goals:
The findings from our experiment indicate diet is capable of influencing the initiation, promotion and final tumor stage in colon cancer. Therefore, diet may serve as a viable countermeasure to help protect against radiation-enhanced colon cancer.
Earth Applications
Earth-Based Applications of Research Project
Information generated from our research project will easily extend to Earth medical research. Individuals exposed to radiation on Earth, either through their profession or for diagnostic or therapeutic radiation procedures, will benefit from the knowledge gained. Our results - and the questions derived from them - should provide avenues for research to address the types of diets that might enhance the risk associated with professional exposure to radiation. It will also determine if there are dietary recommendations that would protect individuals from the increased risk occurring from radiation exposure when it is used for diagnostic techniques. Another area of potential application includes developing dietary recommendations that would benefit individuals undergoing radiotherapy as a cancer treatment by increasing the susceptibility of the cancer cells to the treatment while helping to protect the normal cells.
Information generated from our research project will easily extend to Earth medical research. Individuals exposed to radiation on Earth, either through their profession or for diagnostic or therapeutic radiation procedures, will benefit from the knowledge gained. Our results - and the questions derived from them - should provide avenues for research to address the types of diets that might enhance the risk associated with professional exposure to radiation. It will also determine if there are dietary recommendations that would protect individuals from the increased risk occurring from radiation exposure when it is used for diagnostic techniques. Another area of potential application includes developing dietary recommendations that would benefit individuals undergoing radiotherapy as a cancer treatment by increasing the susceptibility of the cancer cells to the treatment while helping to protect the normal cells.
This project's funding ended in 2004