Mechanism of autophagy in enhanced effects on epirubicin-based chemotherapy by rapamycin in HepG2 cells

Abstract

Objective To explore the effects of rapamycin combined with epirubicin on proliferation of HepG2 cells and the roles of autophagy.Methods HepG2 cells were given rapamycin combined with epirubicin or alone,and divided into four groups.The inhibitory effects of rapamycin combined with epirubicin or alone on proliferation of HepG2 cells were assessed.Mitochondrial membrane was tested by using flow cytometry.The autophagic bodies were observed by using fluorescence staining,and the protein expression levels of p62,LC-3 Ⅰ,LC3 Ⅱ and Beclin1 were detected by using Western blotting.Results The viability of HepG2 cells in rapamycin + epimbicin group was increased significantly as compared with single group [(67.00 ± 2.456) ％ vs.(23.00 ± 1.85) ％,P ＜ 0.05].Mitochondrial membrane in rapamycin + epirubicin group was decreased significantly as compared with single group [green fluorescence ratio (61.14％) vs.(25.73％),P ＜ 0.05].In rapamycin + epirubicin group,the expression of p62 and LC3 Ⅱ was up-regulated.Conclusion Blocking the mammalian target of rapamycin (mTOR) pathway can induce death of cancer cells through autohagic mechanisms,and combined use of rapamycin and epirubicin may synergically enhance the effects of activating autophagy. Key words: Carcinoma, hepatocellular; Mammalian target of rapamycin; Autophagy