Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract only
Publication Acceptance Date: 11/15/2010
Publication Date: 3/17/2011
Citation: Holmstrom, A., Li, X., Wu, R.T., Xiao, Z., Zeng, H., Lei, K.Y., Cheng, W. 2011. Effect of dietary selenium on T cell immunity and cancer xenograft in nude mice. Federation of American Societies for Experimental Biology Conference. 25:110.5. Interpretive Summary:
Technical Abstract: Selenium is known to regulate carcinogenesis and immunity at nutritional and supranutritional levels. Because the immune system provides one of the main body defenses against cancer, we asked whether T cell immunity can modulate selenium chemoprevention. Twenty-four homozygous NU/J nude mice were fed a seleniumdeficient, Torula yeast basal diet alone or supplemented with 0.15 or 1 mg Se/kg (as Na2SeO4) for 8 months in Experiment 1 and 11 weeks in Experiment 2. Mice were injected with PC-3 prostate cancer cells (8-20 x 105 cells/site, 2 sites/mouse), followed by a 7-week tumor development. The athymic, immune-deficient nude mice are known to gradually develop CD8 killer, but not CD4 helper, T cells. Here we show that, prior to xenograft, CD4 and CD8 T cell titers are greater in 28-week old nude mice fed a high selenium diet than the other two diets. Tumor development in adult nude mice (Experiment 1) was suppressed whereas in young nude mice (Experiment 2) was promoted by feeding a high selenium diet. Dietary selenium deficiency does not affect tumor weight. After xenograft, dietary selenium status does not affect levels of CD4 and CD8 T cells in adult nude mice in Experiment 1, while high selenium resulted in significant decrease in CD4 T cells in young nude mice in Experiment 2. Taken together, there is an opposing role of excessive selenium on tumor xenograft development in adult and young nude mice carrying differential T cell profiles.