Soy isoflavones exert differential effects on androgen responsive genes in LNCaP human prostate cancer cells

Author: Rice L, Handayani R, Cui Y, Medrano T, Samedi V, Baker H, Szabo NJ, Rosser CJ, Goodison S, Shiverick KT
Publication: J Nutr. 2007 Apr;137(4):964-72

Epidemiological studies indicate that Asian populations with a high intake of soy products have relatively low rates of prostate cancer. It is generally believed that soy isoflavones are the component responsible for this protective effect. Previous studies have already demonstrated the antiproliferative effect of the genistein, the main soy isoflavone, on prostate cancer cells. Genistein regulates the expression of many proteins involved in progression of prostate cancer.

Lori Rice and her co-workers at the University of Florida investigated the effects of NovaSoy, a commercial isoflavone concentrate extracted from soy, on growth and gene expression profiles in LNCaP cells, an androgen-sensitive human prostate cancer cell line commonly used in the field of oncology. They found that treatment with isoflavones resulted in a dose-dependent decrease in viability and DNA synthesis. The cells also accumulation in G2/M and G0/G1 phases of the cell cycle compared with controls. Treatment with isoflavones upregulated 80 genes and downregulated 33 genes. It was involved androgen-regulated genes and pathways controlling cell cycle, metabolism and intracellular trafficking. More specifically they found that genes that encode for PSA, a major marker of prostate cancer proliferation, were downregulated, whereas for p21CIP1, a protein involved growth arrest, was significantly increased.

The researchers concluded that Novasoy inhibits the growth of the prostate cancer cells through the modulation of cell cycle progression and the differential expression of androgen-regulated genes.