title: The deletion mutant EGFRvIII significantly contributes to stress resistance typical for the tumour microenvironment.
abstract: OBJECTIVE
  The epidermal growth factor receptor (EGFR) is overexpressed or mutated in many tumour types. The truncated, constitutively active EGFRvIII variant has not been detected in normal tissues but is found in many malignancies. In the current study, we have investigated the hypothesis that EGFRvIII contributes to a growth and survival advantage under tumour microenvironment-related stress conditions.
  
  
  METHODS
  U373MG doxycycline-regulated isogenic cells expressing EGFRwt or EGFRvIII were created and validated using Western blot, FACS and qRT-PCR. In vitro proliferation was evaluated with standard growth assays. Cell survival was assayed using clonogenic survival. Animal experiments were performed using NMRI-nu-xenografted mice.
  
  
  RESULTS
  Inducible isogenic cell lines were created and showed high induction of EGFRwt and EGFRvIII upon doxycycline addition. Overexpression of EGFRvIII but not of EGFRwt in this model resulted in a growth and survival advantage upon different tumour microenvironment-related stress conditions in vitro. Induction of EGFRvIII increased tumour growth in vivo, which was reversible upon loss of expression.
  
  
  CONCLUSIONS
  Under conditions where nutrients are limited and stress is apparent, as in the tumour microenvironment, expression of EGFRvIII leads to a growth and survival advantage. These data indicate a potential selection of EGFRvIII-expressing tumour cells under such stress conditions.
authors.affiliation: Maastricht Radiation Oncology (MaastRo) Lab, Grow-School for Oncology and Developmental Biology, University of Maastricht, The Netherlands. jan.theys@maastro.unimaas.nl
authors.forename: Jan
authors.initials: J
authors.lastname: Theys
authors.forename: Barry
authors.initials: B
authors.lastname: Jutten
authors.forename: Ludwig
authors.initials: L
authors.lastname: Dubois
authors.forename: Kasper M A
authors.initials: KM
authors.lastname: Rouschop
authors.forename: Roland K
authors.initials: RK
authors.lastname: Chiu
authors.forename: Younan
authors.initials: Y
authors.lastname: Li
authors.forename: Kim
authors.initials: K
authors.lastname: Paesmans
authors.forename: Philippe
authors.initials: P
authors.lastname: Lambin
authors.forename: Guido
authors.initials: G
authors.lastname: Lammering
authors.forename: Bradly G
authors.initials: BG
authors.lastname: Wouters
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D004318:Doxycycline / Q000494:pharmacology*; D004777:Environment; D066246:ErbB Receptors / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D005434:Flow Cytometry; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D005909:Glioblastoma / Q000188:drug therapy / Q000235:genetics; D006801:Humans; D016014:Linear Models; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D011336:Probability; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D013312:Stress, Physiological; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: C410723:epidermal growth factor receptor VIII; D066246:ErbB Receptors; D004318:Doxycycline