Genistein Arrests Cell Cycle Progression at G₂-M

Abstract

Genistein, an isoflavone, is a specific inhibitor of tyrosine kinase and topoisomerase II. However, its effect on cell growth is unknown. Therefore, we examined the effects of genistein on cell growth and cell cycle progression and compared its effects with other flavonoids. Genistein inhibited in a dose-dependent manner the growth of HGC-27 cells derived from human gastric cancer. Flow-cytometric analysis showed that genistein almost completely arrested the cell cycle progression at G₂-M. This effect was reversible when genistein was removed from the culture medium. In contrast, other flavonoids such as flavone, luteolin, and the structurally similar daidzein arrested the cell cycle at G₁. Consistent with the flow-cytometric analysis, microscopic observation showed that genistein did not increase the mitotic index, which supposes that genistein may arrest the cell cycle at G₂ or early M. These results suggest that the G₂-M arrest by genistein is a unique effect among flavonoids.