Studies on the anti-tumor activities of the soy isoflavone daidzein on murine neuroblastoma cells

Daidzein (4′,7-dihydroxyisoflavone) and genistein (4′,5,7-trihydroxyisoflavone) are two major isoflavones found predominantly in soy beans, as well as in certain traditional Chinese medicinal herbs and tea leaves. In the past decade, there have been extensive studies on the anti-tumor effects of genistein on cancers of the breast, prostate and colon in humans. However, the anti-tumor effects of daidzein on neuronal cancer cells and its action mechanisms remain poorly understood. In this study, daidzein was shown to inhibit the proliferation of a number of murine and human neuroblastoma cell lines in vitro. Using the murine neuroblastoma Neuro-2a (BU-1) cells as the cell model, daidzein was also found to prevent the cell cycle progression to G₂/M phase and induced apoptosis of the neuronal tumor cells, as measured by flow cytometry and gel electrophoresis for fragmented DNA respectively. Taken together, our results showed that daidzein could exert pleiotropic effects on the murine neuroblastoma cells, including inhibition of cell proliferation, modulation of cell cycle check point regulation, and triggering of neuronal cell apoptosis.