Short hairpin RNA-mediated fibronectin knockdown delays tumor growth in a mouse glioma model

Neoplasia. 2010 Oct;12(10):837-47. doi: 10.1593/neo.10662.


Glioblastoma multiforme is the most common and lethal primary brain tumor. Glioma progression depends on the rapid proliferation of tumor cells accompanied by an acute immunosuppressive environment, facilitated mainly by tumor infiltration of regulatory T cells (Tregs). In this study, we characterize the role of fibronectin, a high-molecular weight extracellular matrix glycoprotein secreted by tumor cells, in controlling glioma progression and in mediating immunosuppression. Fibronectin binds to membrane-spanning integrin receptors and plays an important role in cell signaling, in defining cellular shape, in mobility, and in regulating the cell cycle. We found that inhibition of fibronectin expression in glioma cells, using short hairpin RNA-mediated silencing of gene expression, delayed cell proliferation in vitro. This delayed growth is explained, in part, by the observed reduced expression of integrin β(1) fibronectin receptor, which was restored by the inhibition of proteosomal activity. In our analysis of the downstream signaling targets of integrin β(1), we demonstrated reduced phosphorylation of Src kinase and STAT-3. We also observed reduced survivin expression that induced a three-fold increased accumulation of fibronectin-knockdown cells in the G(2)/M phase. In an experimental animal model, the fibronectin knockdown tumors had a mean survival advantage of 23 days over wild-type tumors. Moreover, brain samples of animals bearing fibronectin-knockdown tumors showed delayed Treg recruitment. Collectively, we propose that fibronectin is a key mediator of glioma progression because its inhibition delays both tumor progression and immunosuppression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Blotting, Western
  • Brain Neoplasms / genetics
  • Brain Neoplasms / metabolism
  • Brain Neoplasms / therapy*
  • Cell Division / physiology
  • Cell Proliferation
  • Cysteine Proteinase Inhibitors / pharmacology
  • Disease Models, Animal*
  • Fibronectins / genetics*
  • Fibronectins / metabolism*
  • Flow Cytometry
  • G2 Phase / physiology
  • Glioma / genetics
  • Glioma / metabolism
  • Glioma / therapy*
  • Humans
  • Immunoenzyme Techniques
  • Inhibitor of Apoptosis Proteins / genetics
  • Inhibitor of Apoptosis Proteins / metabolism
  • Integrin beta1 / genetics
  • Integrin beta1 / metabolism
  • Leupeptins / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Phosphorylation / drug effects
  • RNA, Messenger / genetics
  • RNA, Small Interfering / genetics*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT3 Transcription Factor / genetics
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Survivin
  • T-Lymphocytes, Regulatory
  • Tumor Cells, Cultured
  • src-Family Kinases / genetics
  • src-Family Kinases / metabolism


  • Birc5 protein, mouse
  • Cysteine Proteinase Inhibitors
  • Fibronectins
  • Inhibitor of Apoptosis Proteins
  • Integrin beta1
  • Leupeptins
  • RNA, Messenger
  • RNA, Small Interfering
  • Repressor Proteins
  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Survivin
  • src-Family Kinases
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde