Abstract:【Abstract】Objective To examine the antitumor effect of BBR on rectal cancer cell lines SW480 in vitro and explored the mechanism.Methods SW480 cell lines were treated with varying BBR concentrations (025μmol/L, 25μmol/L, 50μmol/L, 100μmol/L, 150μmol/L and 200μmol/L). MTT assay was adopted to observe the optimal conceration and cell proliferation. The treatment group SW480 cell was treated with 150μmol/L BBR, and the control group was treated with RPMI1640 medium. Cell cycle of SW480 cell lines was measured with flow cytometry and apoptpsis of SW480 cell was examined by the Annexin V apoptosis assay. The expression of Livin, Ykl40, AKT and Cyclin D1 in SW480 cells were determined by Western blot analysis. Linked immunosorbent assay(ELISA) was used to measure Angiopoietin2 (Ang2) expression level in SW480 cells.Results Cell proliferation in SW480 cell lines was inhibited. The associated with the cell cycle was arrested in G1 phase and BBRtreated SW480 cells showed a significantly greater proportion of apoptosis. The expression levels of Livin, Ykl40, AKT and Cyclin D1 were notably decreased and BBR significantly reduced Ang2 expression level in SW480 cells.Conclusion This results showed that proliferation of rectal cancer SW480 cells was reduced upon BBR treatment. The mechanism involves arresting cell cycle in G1 phase by supressing YKL40/AKT/ Cyclin D1 signaling pathway, inducing apoptosis through decreased expression of Livin, and inhibits angiogenesis via downregulation of Ang2