Mechanism of matrine-induced apoptosis in NB4 cells

Objective To study apoptosis effect of matrine (Mat) on acute promyelocytic leukemia cells (NB4) and its mechanism.Methods NB4 cells were treated with Mat of different concentrations (0.25,0.5,and 1.0 mg·mL^-1) for 24,48,and 72 hours.The morphologic changes of the cells were observed with Hoechst 33258 staining and proliferation inhibition of NB4 cells was determined with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay.Cell cycle and apoptosis rate were analyzed by flow cytometry with annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI) double staining.The relative activity of caspase-3 and caspase-8 were examined with spectrophotometry assay.Results Mat could significantly inhibit the proliferation and induce apoptosis of NB4 cells in a dose- and time-dependent manner compared with the normal control (P < 0.05).Morphology change observation revealed characteristics of cell apoptosis.Mat at the doses of 0.5 and 1.0 mg·mL^-1 could block NB4 cell cycle at G₀/G₁ stage (57.91% and 83.00%) and reduce the proportion of the cells at S stage (40.95% and 16.10%),and significantly increase the activity of caspase-3(77.41±4.01 and 111.78±4.05).Further analysis indicated that Mat at the does of 1.0 mg·mL^-1 could increase the activity of caspase-8(44.98±7.63)(P < 0.05).Conclusion Mat could inhibit the proliferation and induce apoptosis of NB4 cells; the mechanism of the effects may be related to the arrest of G₀/G₁ phase,inhibition of DNA synthesis,and activation of caspase-3 and caspase-8 pathway.