Anticancer effects of methylated and nonmethylated soy isoflavones in precancerous prostate cells
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Human Nutrition Honors Theses; 2009
Prostate cancer is the most frequently diagnosed form of cancer and the second leading cause of cancer related deaths in the United States. Increased consumption of soy is thought to reduce the risk for this disease. More specifically, the isoflavones found in soy are responsible, in part, for these anticancer effects. Isoflavones are organic compounds found in soy and other legumes and it is thought that methylated isoflavones (glycitein, biochanin A, formononetin) may have greater anticancer activity than those without methyl groups (genistein, daidzein, equol). However, the majority of studies, to date, have focused primarily on the nonmethylated isoflavones, genistein and daidzein. Epidemiological evidence also suggests that the anticancer effects of soy may be greatest during the precancerous stages of prostate cancer. Few studies, however, have examined the impact of soy isoflavones during this precancerous stage. This study examined the antiproliferative effects of methylated and nonmethylated soy isoflavones using a precancerous prostate cell line (WPE1-NB14). The precancerous prostate cells were treated with the six different soy isoflavones, three methylated and three nonmethylated, in different concentrations (0-50µM). Cell viability was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. This assay uses MTT to color the living cells in order to determine the cell viability. The results of this study suggest that methylated isoflavones reduced precancerous cell viability to a greater extent than nonmethylated isoflavones and indicate that the methyl group does contribute to the anticancer effects of soy isoflavones in precancerous prostate cells. While most studies focus on nonmethylated isoflavones because they are the most abundant, they are not necessarily the most bioactive. This study demonstrates the positive impact methylated isoflavones can have on prostate cancer prevention.