Lauren Archibald, Brigham Young University
Life Sciences
Increased intake of selenium (Se) and soy have both been shown to reduce risk for prostate cancer, especially if these dietary treatments are combined. The purpose of this project is to determine how the timing of Se supplementation of either a low- or high-soy diet affects prostate cancer risk. [C57BL/6 X FVB] F1 TRAMP (TRansgenic Adenocarcinoma of Mouse Prostate) male mice were fed stock diets low or high in soy. Half of the mice received Se supplementation (4.0 mg Se/kg BW as Se-methylselenocysteine) by gavage 5 d/wk in a 2 X 2 factorial design. Se supplementation began at conception, 6 weeks, 12 weeks, or 18 weeks of age. The mice were then sacrificed at different stages of maturation (4, 12, 18, and 24 weeks). Our results showed that, at 12 weeks of age, urogenital tract weights, a measure of prostate proliferation and tumor volume, were significantly reduced by Se supplementation (p<0.001) and by soy (p=0.044), independent of time of dietary intervention. Histological scores of prostate cancer progression also showed a protective effect of Se supplementation (p=0.030). At this writing, statistical analysis of data from mice sacrificed at 18 weeks is in process. Data derived from 18-week mice, combined with our previous findings from 12-week animals, will allow us to chart the progress of prostate cancer in this model. In addition, results will show how dietary Se and soy may alter disease progression and how the timing of dietary intervention may determine its effects.