Synergistic chemoprotective mechanisms of dietary phytoestrogens in a select combination against prostate cancer

J Nutr Biochem. 2011 Aug;22(8):723-31. doi: 10.1016/j.jnutbio.2010.06.003. Epub 2010 Nov 9.


Combination of dietary phytoestrogens with diverse molecular mechanisms may enhance their anticancer efficacy at physiological concentrations, as evidenced in epidemiological studies. A select combination of three dietary phytoestrogens containing 8.33 μM each of genistein (G), quercetin (Q) and biochanin A (B) was found to be more potent in inhibiting the growth of androgen-responsive prostate cancer cells (LNCaP) as well as DU-145 and PC-3 prostate cancer cells in vitro than either 25 μM of G, B or Q or 12.5+12.5 μM of G+Q, Q+B or G+B. Subsequent mechanistic studies in PC-3 cells indicated that the action of phytoestrogens was mediated both through estrogen receptor (ER)-dependent and ER-independent pathways as potent estrogen antagonist ICI-182780 (ICI, 5 μM) could not completely mask the synergistic anticancer effects, which were sustained appreciably in presence of ICI. G+Q+B combination was significantly more effective than individual compounds or their double combinations in increasing ER-β, bax (mRNA expression); phospho-JNK, bax (protein levels); and in decreasing bcl-2, cyclin E, c-myc (mRNA expression); phospho-AKT, phospho-ERK, bcl-2, proliferating cell nuclear antigen (protein levels) in PC-3 cells. Phytoestrogens also synergistically stimulated caspase-3 activity. Our findings suggest that selectively combining anticancer phytoestrogens could significantly increase the efficacy of individual components resulting in improved efficacy at physiologically achievable concentrations. The combination mechanism of multiple anticancer phytochemicals may be indicative of the potential of some vegetarian diet components to elicit chemopreventive effects against prostate cancer at their physiologically achievable concentrations, in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caspase 3 / genetics
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Cyclin E / genetics
  • Cyclin E / metabolism
  • Diet*
  • Down-Regulation
  • Drug Synergism
  • Estradiol / analogs & derivatives
  • Estradiol / pharmacology
  • Estrogen Antagonists / pharmacology
  • Estrogen Receptor alpha / metabolism
  • Fulvestrant
  • Genistein / pharmacology*
  • Humans
  • Male
  • Mitogen-Activated Protein Kinase 3 / genetics
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Phytoestrogens / pharmacology*
  • Prostatic Neoplasms / drug therapy
  • Quercetin / pharmacology*
  • Signal Transduction
  • Up-Regulation
  • bcl-2-Associated X Protein / genetics
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Cyclin E
  • ESR1 protein, human
  • Estrogen Antagonists
  • Estrogen Receptor alpha
  • Phytoestrogens
  • bcl-2-Associated X Protein
  • Fulvestrant
  • Estradiol
  • Quercetin
  • Genistein
  • Mitogen-Activated Protein Kinase 3
  • p38 Mitogen-Activated Protein Kinases
  • CASP3 protein, human
  • Caspase 3
  • biochanin A