Reverse effects of saikoside on multidrug resistance of human leukemic cell line K562/ADM in vitro

AIM: To study the reverse effects of saikoside(SS) on the multidrug resistance(MDR) of human leukemic cell line K562/ADM and to investigate the related mechanism.METHODS: K562 cells and K562/ADM cells in the culture were treated with SS at the concentrations of 1~100 mg/L.The inhibitory rate of the cell proliferation was measured by MTT assay.Non-cytotoxic dose of SS was determined.K562/ADM cells were treated with SS at non-cytotoxic doses of 1.25,2.5 and 5.0 mg/L with different concentrations of adriamycin(ADM,0.05~100 mg/L).The 50% inhibitory concentration(IC50) and the reversal index in all groups were determined.The cell morphology was observed after treated with SS+ADM.The effects of SS on ADM accumulation in K562/ADM cells,the cell cycle profile and apoptosis were examined by flow cytometry.RESULTS: The inhibitory rates were significantly increased in a dose-dependent manner when the cells were treated with different doses of SS(1~100 mg/L).The available reversal concentration of SS was 5.0 mg/L and the reversal index was 21.5 folds for K562/ADM cells.After treated with SS+ADM,the number of tumor cells was decreased and apoptotic cells were increased in a dose-response relationship.ADM accumulation in K562/ADM cells treated with SS was significantly higher than that in control cells(P0.05).SS may significantly enhanced the apoptosis of K562/ADM cells treated with ADM(P0.05).K562/ADM cells treated with SS were blocked in the stage of G0/G1.CONCLUSION: SS has effect on proliferation inhibition and MDR reversal in K562/ADM cell line.The reversal mechanisms of SS may be due to increasing the accumulation of chemo therapeutics in the cell,inducing the cell apoptosis and arresting the cells in G0/G1 phase.