Mechanism of synergistic antitumor effects of EBB and doxorubicin on multidrug resistant MCF-7/ADR / 中国药理学通报

ABSTRACT

Aim To study the mechanism of synergistic antitumor of EBB and doxorubicin in doxorubicin-resistant MCF-7/ADR breast carcinoma cells.Methods The antitumor activity of doxorubiein alone and its combination with EBB were measured by MTT assay in MCF-7/ADR and MCF-7cells. The rate of doxorubicin-induced apoptosis and the protein and mRNA levels of P-glycoprotein(P-gp) were determined in MCF-7/ADR treated with EBB by flow cytometry (FACS), respectively.Laser scanning confocal microscopy was used to detect the intracellular accumulation of drug in EBB-treated MCF-7 and MCF-7/ADR cells.Results EBB had antitumor effects for MCF-7 and MCF-7/ADR.It could potentiate the antitumor effect of dororubicin with CDI of 0.73 and 0.49 for MCF-7 and MCF-7/ADR,respectively.EBB and doxorubicin acted synergistically in elevating apoptosis of MCF-7/ADR and downregulating the expression of P-gp in a dose-dependent manner in MCF-7/ADR.EBB restored the intracellular accumulation of doxorubicin in MCF-7/ADR cells in a dose-dependent manner.After pretreatment with EBB for 24 h and 48 h,the intracellular accumulation of doxorubicin and Rh123 was obviousely restored in MCF-7/ADR cells compared with control in a time-dependent manner.Conclusion EBB is a potential agent which has strong inhibitory effect on both multidrug resistant cells and their parental cells.EBB can significantly potentiate the antitumor effects of dororubicin in MCF-7/ADR cells by blocking the function of P-glycoprotein and inhibiting the expression of P-glycoprotein.