FHL2 silencing reduces Wnt signaling and osteosarcoma tumorigenesis in vitro and in vivo

PLoS One. 2013;8(1):e55034. doi: 10.1371/journal.pone.0055034. Epub 2013 Jan 28.

Abstract

Background: The molecular mechanisms that are involved in the growth and invasiveness of osteosarcoma, an aggressive and invasive primary bone tumor, are not fully understood. The transcriptional co-factor FHL2 (four and a half LIM domains protein 2) acts as an oncoprotein or as a tumor suppressor depending on the tissue context. In this study, we investigated the role of FHL2 in tumorigenesis in osteosarcoma model.

Methodology/principal findings: Western blot analyses showed that FHL2 is expressed above normal in most human and murine osteosarcoma cells. Tissue microarray analysis revealed that FHL2 protein expression is high in human osteosarcoma and correlates with osteosarcoma aggressiveness. In murine osteosarcoma cells, FHL2 silencing using shRNA decreased canonical Wnt/β-catenin signaling and reduced the expression of Wnt responsive genes as well as of the key Wnt molecules Wnt5a and Wnt10b. This effect resulted in inhibition of osteosarcoma cell proliferation, invasion and migration in vitro. Using xenograft experiments, we showed that FHL2 silencing markedly reduced tumor growth and lung metastasis occurence in mice. The anti-oncogenic effect of FHL2 silencing in vivo was associated with reduced cell proliferation and decreased Wnt signaling in the tumors.

Conclusion/significance: Our findings demonstrate that FHL2 acts as an oncogene in osteosarcoma cells and contributes to tumorigenesis through Wnt signaling. More importantly, FHL2 depletion greatly reduces tumor cell growth and metastasis, which raises the potential therapeutic interest of targeting FHL2 to efficiently impact primary bone tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / genetics
  • Bone Neoplasms / drug therapy
  • Bone Neoplasms / genetics
  • Bone Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Cell Proliferation
  • Cell Transformation, Neoplastic / genetics*
  • Female
  • Gene Expression Regulation, Neoplastic / genetics
  • Gene Silencing*
  • Humans
  • LIM-Homeodomain Proteins / deficiency*
  • LIM-Homeodomain Proteins / genetics*
  • Lung Neoplasms / secondary
  • Mice
  • Molecular Targeted Therapy
  • Muscle Proteins / deficiency*
  • Muscle Proteins / genetics*
  • Neoplasm Invasiveness
  • Osteosarcoma / drug therapy
  • Osteosarcoma / genetics
  • Osteosarcoma / pathology*
  • RNA, Small Interfering / genetics
  • Signal Transduction / genetics*
  • Transcription Factors / deficiency*
  • Transcription Factors / genetics*
  • Wnt Proteins / metabolism*
  • beta Catenin / metabolism

Substances

  • FHL2 protein, human
  • LIM-Homeodomain Proteins
  • Muscle Proteins
  • RNA, Small Interfering
  • Transcription Factors
  • Wnt Proteins
  • beta Catenin

Grants and funding

Julia Brun is a recipient of a Ph.D. Award from the DIM Stem Pôle Ile de France (Paris, France). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.