title: Apelin-13 induces autophagy in hepatoma HepG2 cells through ERK1/2 signaling pathway-dependent upregulation of Beclin1.
abstract: The aim of the present study was to investigate the effect of Apelin-13 on autophagy in hepatocellular carcinoma HepG2 cells and the underlying mechanism of the effect. The HepG2 cells were treated with Apelin-13 at a final concentration of 0.0001, 0.001, 0.01 and 0.1 µmol/l for 24 h. Cells were also treated with 10 µmol/l PD98059 for 24 h. The expression of the extracellular signal-regulated kinase (ERK)1/2, phosphorylated ERK1/2 (pERK1/2) and Beclin1 proteins were detected by western blot analysis. Beclin1 mRNA expression was also detected by reverse transcription-polymerase chain reaction. Autophagy was observed using fluorescence microscopy subsequent to monodansylcadaverine (MDC) staining. Following treatment with the various concentrations of Apelin-13, the expression of the ERK1/2 protein remained at a similar level, whereas the expression of pERK1/2 increased in a dose-dependent manner. Compared with the control group, the increase was significant (P<0.05). Similarly, Beclin1 expression was upregulated at the protein and mRNA levels by Apelin-13 treatment in a dose-dependent manner and was significantly increased compared with the control group. However, following treatment with the Apelin-13 inhibitor PD98059, the expression of pERK1/2, Beclin1 protein and Beclin1 mRNA were significantly decreased (P<0.05). In addition, Apelin-13 induced the autophagy of HepG2 cells in a dose-dependent manner, as revealed by MDC staining. PD98059 inhibited autophagy of HepG2 cells induced by Apelin-13. Therefore, Apelin-13 may promote autophagy in HepG2 cells by inducing the phosphorylation of ERK1/2 and upregulating the expression of Beclin1.
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Qiulin
authors.initials: Q
authors.lastname: Huang
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Cao
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Junyue
authors.initials: J
authors.lastname: Lei
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Dong
authors.initials: D
authors.lastname: Han
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Jia
authors.initials: J
authors.lastname: Yu
authors.affiliation: Institute of Pharmacy and Pharmacology, University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Linxi
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of General Surgery, First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Deguan
authors.initials: D
authors.lastname: Lv
authors.affiliation: Department of Microbiology, School of Medicine, University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Li
keywords: expression levels; extracellular signal-regulated kinase 1/2; phosphorylation