NETRIN-4 protects glioblastoma cells FROM temozolomide induced senescence

PLoS One. 2013 Nov 12;8(11):e80363. doi: 10.1371/journal.pone.0080363. eCollection 2013.

Abstract

Glioblastoma multiforme is the most common primary tumor of the central nervous system. The drug temozolomide (TMZ) prolongs lifespan in many glioblastoma patients. The sensitivity of glioblastoma cells to TMZ is interfered by many factors, such as the expression of O-6-methylguanine-DNA methyltransferase (MGMT) and activation of AKT signaling. We have recently identified the interaction between netrin-4 (NTN4) and integrin beta-4 (ITGB4), which promotes glioblastoma cell proliferation via activating AKT-mTOR signaling pathway. In the current work we have explored the effect of NTN4/ITGB4 interaction on TMZ induced glioblastoma cell senescence. We report here that the suppression of either ITGB4 or NTN4 in glioblastoma cell lines significantly enhances cellular senescence. The sensitivity of GBM cells to TMZ was primarily determined by the expression of MGMT. To omit the effect of MGMT, we concentrated on the cell lines devoid of expression of MGMT. NTN4 partially inhibited TMZ induced cell senescence and rescued AKT from dephosphorylation in U251MG cells, a cell line bearing decent levels of ITGB4. However, addition of exogenous NTN4 displayed no significant effect on TMZ induced senescence rescue or AKT activation in U87MG cells, which expressed ITGB4 at low levels. Furthermore, overexpression of ITGB4 combined with exogenous NTN4 significantly attenuated U87MG cell senescence induced by TMZ. These data suggest that NTN4 protects glioblastoma cells from TMZ induced senescence, probably via rescuing TMZ triggered ITGB4 dependent AKT dephosphorylation. This suggests that interfering the interaction between NTN4 and ITGB4 or concomitant use of the inhibitors of the AKT pathway may improve the therapeutic efficiency of TMZ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents, Alkylating / pharmacology*
  • Cell Line, Tumor
  • Cellular Senescence / drug effects*
  • Cellular Senescence / genetics*
  • Dacarbazine / analogs & derivatives*
  • Dacarbazine / pharmacology
  • Dose-Response Relationship, Drug
  • Gene Expression
  • Gene Silencing
  • Glioblastoma / genetics*
  • Glioblastoma / metabolism*
  • Humans
  • Integrin beta4 / genetics
  • Integrin beta4 / metabolism
  • Nerve Growth Factors / genetics*
  • Nerve Growth Factors / metabolism*
  • Netrins
  • Phosphorylation / drug effects
  • Proto-Oncogene Proteins c-akt / metabolism
  • Temozolomide

Substances

  • Antineoplastic Agents, Alkylating
  • ITGB4 protein, human
  • Integrin beta4
  • NTN4 protein, human
  • Nerve Growth Factors
  • Netrins
  • Dacarbazine
  • Proto-Oncogene Proteins c-akt
  • Temozolomide

Grants and funding

This research was supported by grants from the Finnish Cultural Foundation; the Academy of Finland (grant number 139236); the Finnish Cancer Foundation; the Sigrid Juselius Foundation; Finska Läkaresällskapet; the Finnish Society of Sciences and Letters; Biocentrum Helsinki; Helsinki University Hospital Fund and the University of Helsinki; Helsinki Biomedical Graduate Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.