OBJECTIVETo study the effect of embelin on proliferation, differentiation and apoptosis of HL-60 cells and explore its possible mechanism.

METHODSDifferent concentration of embelin were used to treat HL-60 cells. Cell growth curve was analysed by MTT assay, cell apoptosis by Annexin V/PI double staining and JC-1 dye. The differentiation of HL-60 cells was evaluated by expression of CD33, CD34, CD11b and CD14. Bone marrow cells (BMC) from nine patients with acute nonlymphocytic leukemia (ANML) were also studied.

RESULTSEmbelin induced differentiation of HL-60 cells with significant increase of CD14 and CD11b expression at 33.97µmol/L for 3 days (P < 0.01). Embelin induced apoptosis of HL-60 cells in a time- and dose-dependent manner, the apoptosis rates were (9.23 ± 0.05)%, (25.86 ± 0.30)% and (39.03 ± 0.07)% respectively at 339.67 µmol/L of embelin for 12-, 24- and 48-hours treatment (P < 0.05); the apoptosis rates were (0.07 ± 0.03)%, (7.43 ± 0.30)%, (14.01 ± 0.01)%, (25.52 ± 0.03)% and (39.15 ± 0.01)% respectively at 10.19, 33.97, 101.90, 339.67 and 1019.02 µmol/L of embelin for 24-hours culture (P < 0.05). Clusters of differentiation antigen on BMC from three acute promyelocytic leukemia patients showed significant changes at 33.97 µmol/L of embelin treatment for 3 days. Embelin induced apoptosis of BMCs from all the nine ANML patients at 33.97 µmol/L for 24 hour.

CONCLUSIONEmbelin can inhibit proliferation and induce differentiation and apoptosis of HL-60 cells. The mechanism may be related to mitochondrial apoptosis pathway. Embelin at subtoxic concentration doesn't promote leukemia BMC differentiation, but at 339.67 µmol/L induces apoptosis of these cells.