Effects of soy supplementation on gene expression in breast cancer. Homo sapiens

Background There are conflicting reports on the impact of soy on breast carcinogenesis. This study examines the effects of soy supplementation on breast cancer-related genes and pathways. Methods Women (n = 140) with early-stage breast cancer were randomized to soy protein supplementation (n = 70) or placebo (n = 70) for 7 to 30 days, from diagnosis until surgery. Adherence was determined by plasma isoflavones: genistein and daidzein. Gene expression changes were evaluated by NanoString inin pre- and post-treatment tumor tissue. Genome-wide expression analysis was performed on post-treatment tissue. Proliferation (Ki67) and apoptosis (Cas3) were assessed by immunohistochemistry. Results Plasma isoflavones rose in the soy group (two-sided Wilcoxon rank-sum test, P 2 fold) of cell cycle transcripts, including those which promote cell proliferation, such as FGFR2, E2F5, BUB1, CCNB2, MYBL2, CDK1, and CDC20 (P < .01). Soy intake did not result in statistically significant changes in Ki67 or Cas3. Conclusions Gene expression associated with soy intake and high plasma genistein define a signature characterized by overexpression of FGFR2 and genes that drive cell cycle and proliferation pathways. These findings raise the concerns that in a subset of women soy could adversely affect gene expression in breast cancer. Overall design: Genome-wide expression analysis was performed on breast cancer tissue from women following treatment with soy (n=28) or placebo (n=23).