Background: Deguelin is an natural rotenoid extraction from leguminous plants and has potent antitumor effects in vitro and in vivo.It has been demonstrated that deguelin restrains cell proliferation,induces cell apoptosis,causes cell cycle arrest and inhibits tumor angiogenesis by regulating many molecular pathways,but the specific anti-tumor mechanism remains unclear.Objective: Our study aimed to investigate the role of Deguelin for regulation of CyclinD1 expression in Zebrafish embryos and related cancer cells.Methods: In this study,cell growth inhibition of deguelin on MCF-7 breast cancer cell and H1299 lung cancer cell was studied by MTT.Apoptosis induction and cell cycle arresting effect of deguelin on cancer cells was detected by flow cytometry on cell level.In vivo experiment,we do research on the development effect of deguelin on zebrafish embryos,expression of CylinD1 by the whole amount in situ hybridization.For further study,the expression changes of CyclinD1 mRNA in MCF-7、H1299 cells and zebrafish embryos were tested by real-time PCR to provide a theoretical basis for the mechanism of the antitumor effects of deguelin.Results: Deguelin can inhibit the proliferation of breast cancer cells MCF-7 and lung cancer cells H1299,arrest the cell cycle in G2/M phase and induce cell apoptosis.Low concentrations of 1deguelin significantly inhibited the development of zebrafish embryos in a dose-dependentmanner.400nM deguelin treatment caused the embryo developmental stagnation after dosingperiod of 6-7h.600nM deguelin treatment make embryos developmental stagnation after dosing period of 3-4h.400nM deguelin almost completely inhibited the expression of CyclinD1 in shield phase zebrafish embryos(about 0.75 hour post fertilization).Expression of CyclinD1 in brain,retina area,trunk,somites and tail of the 24hpf zebrafish embryos were significantly reduced after 100nM deguelin treatment.By real-time PCR analysis,deguelin significantly reduced CyclinD1 mRNA expression levels in zebrafish embryos and MCF-7,H1299 cells(P <0.05).Conclusions: Deguelin can down-regulate the expression of CyclinD1 mRNA significantly in MCF-7 、H1299 cells and zebrafish embryos,However,at the same concentrations,the normal cell has little effect on the growth.