MicroRNA-181a Inhibits Autophagy By Targeting ATG5 In Hepatocellular Carcinoma

Background:Hepatocellular cancer(HCC)is the most common primary malignancy of hepatocytes which accounts for about 90%of primary liver cancers,and is a leading cause of death from cancer in global.In the development of HCC,a defective autophagy response contribute to this process.However,other researchers thought autophage-deficiency may promote the HCC.Thus,it's still needed to elucidate the role of autophage in HCC,and how autophagy is regulated in HCC.Interestingly,microRNA-181a(miR-181a)was found to inhibiting autophagy in several tumors,such as breast cancer,gastric cancer,and neuroblastoma.However,the role of miR-181a in the autophagy of HCC remains unclear.Recent study found that in HCC,miR-181a was up-regulated,which may be related with HCC pathogenesis.Thus,we will investigate the role of miR-181a in the autophagy of HCC in this study.Methods:The expression of miRl-181a was detected by QPCR in human hepatocellular carcinoma tissues and hepatic hemangioma tissues.The expression of autophagy was detected by WB.Double luciferase reporter assay was used to analyze the target gene of miR-181a acting on HCC.The effect of miR-181a on early apoptosis of HCC cells by flow cytometry.The effect of miR-181a on the proliferation of HCC was further verified by subcutaneous tumor formation in nude mice.Results:We found that the expression of miR-181a was increased in HCC.By detecting the expression levels of LC3,p62 and Atg5 protein in liver cancer tissues,we found that the expression of autophagy was decreased in HCC.miR-181a inhibition up-regulates autophagy in HepG2 cells.The targeting of miR-181a was validated by Luciferase assay.This result suggests that mir-181a can bind to 3'-UTR of ATG5 and the ATG5 is the target gene of miR181a in HepG2 cells.The apoptosis of HepG2 cells was assessed by flow cytometry.This result suggests that miR-181a inhibition could promote the apoptosis of HepG2 cells.In mice of injecting miR-181a sponge-transfected HepG2 cells,the tumor volume and weight was significantly lower than that in controls.These results suggested that miR-181a inhibition could inhibit tumor growth.Conclusions:We study found that miR-181a could inhibit autophagy of HCC by targeting on ATG5,resulting in a decreased apoptosis of HCC cells and an increased tumor growth in xenograft.These findings may provide a novel target on HCC treatment.