ABSTRACT
Background and purpose: AMP-activated protein kinase (AMPK) plays an important role in the regulation of cell metabolism and energy balance and is associated with cell proliferation, survival and multiple signaling pathways. Recent reports found that AMPK is involved in tumor suppression and drug resistance. The aim of this study was to explore the effect of AMPK on the anti-tumor effect of adriamycin and underlying mechanism in breast cancer MCF-7/adr cells. Methods:The anti-proliferative effects of adriamycin was detected by methyl thiazolyl tetrazolium (MTT) assay in MCF-7/adr, MCF-7/adr-vector and MCF-7/adr-AMPKαcells. The cell morphology in each group was stained with the lfuorescent dye Hoechst 33528, and the effects on apoptosis induction were examined by lfow cytometry (FCM). The intracellular concentration of adriamycin was detected by lfuorescence assay. The resis-tance-and apoptosis-related proteins were analyzed by Western blot. Results:The growth of breast cancer MCF-7/adr cells was inhibited by adriamycin in a dose-and time-dependent manner. The IC50 values at 24 and 48 h were (36.8±2.1) and (28.8±1.3) μg/mL, respectively. AMPKαover-expression enhanced the cytotoxic effect of adriamycin in MCF-7/adr-AMPKαcells in a dose-and time-dependent manner. Its IC50 values at 24 and 48 h were (16.0±0.7) and (4.2±0.2) μg/mL, respectively. Fluorescent morphological assay showed that AMPKαoverexpression contributed to adriamycin induced apoptosis in MCF-7/adr-AMPKαcells. After treatment with 1.0 μg/mL adriamycin for 48 h, the apoptosis rates of MCF-7/adr, MCF-7/adr-vector and MCF-7/adr-AMPKα cells were (12.0±1.4)%, (12.7±1.6)% and (32.0±4.2)%, respectively, indicating that overexpression of AMPKα enhanced the adriamycin-induced apoptosis in MCF-7/adr cells. Fluorescence microplate assay showed that over expression of AMPKαsigniifcantly increased the intracellular accumulation of adriamycin, in a concentration dependent manner. Western blot analysis showed that, compared with MCF-7/adr and MCF-7/adr-vector cells, the expressions of Bax, caspase-3 and cleaved PARP proteins were increased. Meanwhile, Bcl-2 and P-gp protein expressions were decreased in MCF-7/adr-AMPKαcells. Furthermore, the release of cytochrome c from mitochondria into the cytosol was also observed in MCF-7/adr-AMPKαcells. Conclusion:AMP-Kαoverexpression can enhance the chemosensitivity of breast cancer MCF-7/adr cells to adriamycin through inhibiting the drug effux transporter and regulating the expression of apoptosis-related proteins.