Differentiation of promyelocytic leukemia cells HL-60 induced by daidzein in vitro and in vivo.

We have screened more than one thousand synthetic and natural chemicals to explore differentiation inducers and found that daidzein has potent differentiation-inducing activity for human leukemia HL-60 cells, both in vitro and in vivo. In vitro study showed that daidzein at concentrations exceeding 10 micrograms/ml caused inhibition of HL-60 cells; and it induced differentiation of the cells into granulocytic lineage as judged by NBT reduction activity, phagocytic ability and morphological characteristics. Flow cytometry study indicated that daidzein arrested HL-60 cells in the G1 phase. The growth of HL-60 cells in the subrenal capsules of mice and in diffusion chambers implanted into the peritoneal cavities of mice was inhibited by 50 mg/kg daidzein. HL-60 cells treated with daidzein in vivo also exhibited characteristic morphological changes of matured cells. Moreover, the colony forming efficiency of HL-60 cells in diffusion chambers in mice was markedly inhibited by the administration of daidzein.