Interleukin-6-stimulated progranulin expression contributes to the malignancy of hepatocellular carcinoma cells by activating mTOR signaling

Sci Rep. 2016 Feb 16:6:21260. doi: 10.1038/srep21260.

Abstract

This study aimed to determine the expression of progranulin (PGRN) in hepatocellular carcinoma (HCC) cells in response to interleukin 6 (IL-6), a non-cellular component of the tumor microenvironment, and the molecular mechanism of PGRN oncogenic activity in hepatocarcinogenesis. Levels of IL-6 and PGRN were increased and positively correlated in HCC tissues. IL-6 dose- and time-dependently increased PGRN level in HCC cells. IL-6-driven PGRN expression was at least in part mediated by Erk/C/EBPβ signaling, and reduced expression of PGRN impaired IL-6-stimulated proliferation, migration and invasion of HepG2 cells. PGRN activated mammalian target of rapamycin (mTOR) signaling, as evidenced by increased phosphorylation of p70S6K, 4E-BP1, and Akt-Ser473/FoxO1. Inhibition of mTOR signaling with rapamycin, an mTOR signaling inhibitor, disturbed PGRN- or IL-6-mediated proliferation, migration and invasion of HCC cells in vitro. Persistent activation of mTOR signaling by knockdown of TSC2 restored PGRN-knockdown-attenuated pro-proliferation effects of IL-6 in HepG2 cells. In addition, rapamycin treatment in vivo in mice slowed tumor growth stimulated by recombinant human PGRN. Our findings provide a better understanding of the biological activities of the IL-6/PGRN/mTOR cascade in the carcinogenesis of HCC, which may suggest a novel target in the treatment of HCC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoma, Hepatocellular / genetics*
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Proliferation
  • Cell Survival
  • Disease Models, Animal
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Heterografts
  • Humans
  • Intercellular Signaling Peptides and Proteins / genetics*
  • Interleukin-6 / metabolism*
  • Liver Neoplasms / genetics*
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology
  • Mice
  • Progranulins
  • Signal Transduction*
  • Sirolimus / pharmacology
  • TOR Serine-Threonine Kinases / metabolism*
  • Tumor Burden / drug effects

Substances

  • GRN protein, human
  • Intercellular Signaling Peptides and Proteins
  • Interleukin-6
  • Progranulins
  • TOR Serine-Threonine Kinases
  • Extracellular Signal-Regulated MAP Kinases
  • Sirolimus