| Through epidemical studies, it is known that Asian men, whose diets are high in soy products, have a much lower incident of hormone-dependent disease such as prostate cancer. Vitamins are essential for normal metabolism, growth, development and general health. Recent research has shown that vitamins might have important roles in cancer prevention or even treatment as antioxidants and hormones. This study was designed to investigate the effect of the vitamin E, soy isoflavones and a combination of the two on PC-3 prostate cancer cells in vivo and in vitro. For the in vivo studies, 24 nude mice were injected with PC-3 cells and randomly assigned to 1 of 4 diets including; control, high vitamin E, high soy-isoflavone, and high soy-isoflavone high vitamin E. There were no significant differences in tumor growth between the groups in the study. For the in vitro studies, PC-3 cells were treated with various concentrations of soy isoflavones, vitamin E (alpha-Tocopherol) alone or in combination. Cell proliferation was then measured using 3H-Thymidine Incorporation Assays. Unexpectedly, the isoflavones increased cell proliferation of PC-3 cells, especially at the higher concentrations; however, both vitamin E and isoflavone genistein in combination with vitamin E reduced PC-3 proliferation at concentrations of 10-5 M. In conclusion, these results suggest that vitamin E alone or in combination with the soy isoflavone genistein may prove to be a potential dietary therapy for prostate cancer. However, the observation that soy isoflavones alone do not reduce PC-3 growth in vitro or in vivo, and stimulate proliferation in vitro requires further investigation and raises some concerns over the use of soy in the treatment prostate cancer. |
