Phosphorylated Heat Shock Protein 20 (HSPB6) Regulates Transforming Growth Factor-α-Induced Migration and Invasion of Hepatocellular Carcinoma Cells

PLoS One. 2016 Apr 5;11(4):e0151907. doi: 10.1371/journal.pone.0151907. eCollection 2016.

Abstract

Human hepatocellular carcinoma (HCC) is one of the major malignancies in the world. Small heat shock proteins (HSPs) are reported to play an important role in the regulation of a variety of cancer cell functions, and the functions of small HSPs are regulated by post-translational modifications such as phosphorylation. We previously reported that protein levels of a small HSP, HSP20 (HSPB6), decrease in vascular invasion positive HCC compared with those in the negative vascular invasion. Therefore, in the present study, we investigated whether HSP20 is implicated in HCC cell migration and the invasion using human HCC-derived HuH7 cells. The transforming growth factor (TGF)-α-induced migration and invasion were suppressed in the wild-type-HSP20 overexpressed cells in which phosphorylated HSP20 was detected. Phospho-mimic-HSP20 overexpression reduced the migration and invasion compared with unphosphorylated HSP20 overexpression. Dibutyryl cAMP, which enhanced the phosphorylation of wild-type-HSP20, significantly reduced the TGF-α-induced cell migration of wild-type HSP20 overexpressed cells. The TGF-α-induced cell migration was inhibited by SP600125, a c-Jun N-terminal kinases (JNK) inhibitor. In phospho-mimic-HSP20 overexpressed HuH7 cells, TGF-α-stimulated JNK phosphorylation was suppressed compared with the unphosphorylated HSP20 overexpressed cells. Moreover, the level of phospho-HSP20 protein in human HCC tissues was significantly correlated with tumor invasion. Taken together, our findings strongly suggest that phosphorylated HSP20 inhibits TGF-α-induced HCC cell migration and invasion via suppression of the JNK signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracenes / pharmacology
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism*
  • Carcinoma, Hepatocellular / pathology
  • Cell Line, Tumor
  • Cell Movement*
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / genetics
  • HSP27 Heat-Shock Proteins / biosynthesis*
  • HSP27 Heat-Shock Proteins / genetics
  • Humans
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism*
  • Liver Neoplasms / pathology
  • MAP Kinase Kinase 4 / antagonists & inhibitors
  • MAP Kinase Kinase 4 / genetics
  • MAP Kinase Kinase 4 / metabolism
  • Neoplasm Invasiveness
  • Neoplasm Proteins / antagonists & inhibitors
  • Neoplasm Proteins / biosynthesis*
  • Neoplasm Proteins / genetics
  • Phosphorylation / genetics
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Transforming Growth Factor alpha / biosynthesis*
  • Transforming Growth Factor alpha / genetics

Substances

  • Anthracenes
  • HSP27 Heat-Shock Proteins
  • HSPB7 protein, human
  • Neoplasm Proteins
  • Transforming Growth Factor alpha
  • pyrazolanthrone
  • MAP Kinase Kinase 4

Grants and funding

This work was supported in part by a Grant-in-Aid for Scientific Research (25460989 to O.K.) from the Ministry of Education, Science, Sports and Culture of Japan. https://www.jsps.go.jp/english/index.html. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.