OBJECTIVETo study the effect of macrocalyxin A (MA) on proliferation, differentiation and apoptosis in HL-60 cells and explore its possible mechanisms.

METHODSDifferent concentration of MA were used to treat HL-60 cells. Proliferation inhibition was analyzed by Trypan blue staining and MTT assay, cell apoptosis by cell morphology, DNA content, cell cycle analysis, Annexin-V/PI and Hoechst 33258 fluorescence staining. The differentiation of HL-60 cells was evaluated by cell morphology, NBT tests and expression of CD11b, CD13, CD14. The expressions of bcl-2, bax, Fas, P53, mitochondrial transmembrane-potential (DeltaPsim) and mitochondrial membrane protein were analyzed by flow cytometry.

RESULTSMA could inhibit HL-60 cells proliferation capacity in a time-and dose-effect, with a 24 h IC50 value of 8.76 microg/ml, 48 h of 7.17 microg/ml and 72 h of 7.14 microg/ml. The HL-60 cells apoptosis was confirmed by cell morphology, sub-G1 phase and Annexin-V/PI labeling in a time and dose dependent manner. The more mature HL-60 cells were a with higher positivity of NBT and expressions of CD11b than those cultured without MA. The expression of bax was increased, while bcl-2, P53, Fas were unchanged on the MA treatment. MA could increase the expression of mitochondrial membrane protein in a dose-dependent manner while the DeltaPsim was reduced.

CONCLUSIONMA can inhibit proliferation and induce differentiation and apoptosis of the HL-60 cells. The mechanism may be related with up-regulating bax, opening the mitochondrial permeability transition pore and reducing DeltaPsim.