Objective To investigate the mechanism of(-)-epicatechin(EC)in improving the radiosensitivity of non-small cell lung cancer cells by combining radiotherapy(RT).Methods A549 human non-small cell lung cancer cells were cul-tured in vitro to construct a radiotherapy-resistant cell line A549R.Cell proliferation activity was detected by Cell Counting Kit-8(CCK-8).The cell apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labe-ling(TUNEL)staining.Transwell assay was used to detect cell migration ability.The expressions of apoptosis-related proteins(Bcl-2,Bax,Cleaved Caspase-3)and autophagy-related proteins(Beclin,LC3Ⅱ/Ⅰ)were detected by Western blot.The ex-pressions of Cleaved Caspase-3 and LC3 were detected by immunofluorescence staining.Monodansylcadaverine(MDC)staining was used to detect the formation of autophagosomes.Results EC combined with RT inhibited cell proliferation and migration,in-duced cell apoptosis and autophagy,down-regulated the expression of Bcl-2,up-regulated the expressions of Bax,Cleaved Caspase-3,Beclin and LC3Ⅱ/Ⅰ,while the effect of EC combined with RT was partially attenuated by the treatment with autoph-agy inhibitor(chloroquine,CQ)or mTOR signaling pathway activator MHY1485.Conclusion EC can be used as a radiosensitizer to improve the radiosensitivity of A549R cells by inhibiting mTOR signaling pathway to induce autophagy and apoptosis.
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