ABSTRACT
OBJECTIVE: The objective of this study was to investigate the reversal effects of 5,5'-dimethoxylariciresinol-4'-O-ß-D-glucoside (DMAG) extracted from traditional Chinese medicines Mahonia on multidrug resistance (MDR) of human leukemia cells to chemotherapeutic agents. MATERIALS AND METHODS: MTT(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed to determine the effect of DMAG on doxorubicin sensitivity to K562/DOX cells. Propidium iodide /Hoechst 33342 double staining assay was used to investigate the effect of DMAG on doxorubicin-induced cellular apoptosis. Intracellular accumulation of doxorubicin and rhodamine 123 assay were performed to evaluate the effect of DMAG on drugs efflux activity of P-glycoprotein. RESULTS: DMAG significantly enhanced the doxorubicin cytotoxicity to K562/DOX cells. In the presence of 1.0 µM of DMAG, the IC50 of doxorubicin decreased from 34.93 ± 1.37 µM to 12.51 ± 1.28 µM. DMAG of 1.0 µM significantly enhanced doxorubicin-induced cell apoptosis in K562/DOX cells and the enhancement was time-dependent. A significant increase in accumulation of doxorubicin in the presence of DMAG was observed. After treatment of the K562/DOX cells for 1 h with 15.0 µM doxorubicin alone, the fluorescence intensity was 33093.12. With the addition of 1.0 µM of DMAG, the fluorescence intensity of doxorubicin was 2.3-fold higher. A significant increase of accumulation of rhodamine 123 in the presence of DMAG was also observed. With the addition of 1.0 µM of DMAG, the fluorescence intensity was increased by 49.11% compared with rhodamine 123 alone. CONCLUSION: DMAG was shown to effectively enhance chemosensitivity of resistant cells, which makes it might be a suitable candidate for potential MDR-reversing agents.
