Abstract
This study aimed to investigate the relationship between interleukin-6 (IL-6) and NS5ATP9 in autophagy of liver cancer cells. Autophagy is one of the important regulators of the replication of hepatitis C virus and the survival of tumors. IL-6 is a multifunctional cytokine that plays an important role in autophagy and development of many kinds of tumors. However, the role of IL-6 in autophagy has not been fully explored. A previous study had shown that a novel gene, NS5ATP9, could modulate autophagy. The present study demonstrated that human IL-6 recombinant protein induced autophagy of HepG2 cells. Conversely, autophagy decreased after IL-6 was silenced or neutralized with monoclonal antibody against human IL-6. In addition, NS5ATP9 was upregulated by IL-6 via nuclear factor-kappaB activation, as detected by Western blot. Further studies indicated that the induction of autophagy by IL-6 could be attenuated by silencing NS5ATP9. Interestingly, the expression of NS5ATP9, in turn, resulted in the upregulation of IL-6. In conclusion, IL-6 could induce autophagy by expressing NS5ATP9, while NS5ATP9 upregulated IL-6 levels in turn, which further induced autophagy.