The deletion mutant EGFRvIII significantly contributes to stress resistance typical for the tumour microenvironment.
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.
Theys
Jan
J
Maastricht Radiation Oncology (MaastRo) Lab, Grow-School for Oncology and Developmental Biology, University of Maastricht, The Netherlands. jan.theys@maastro.unimaas.nl
Jutten
Barry
B
Dubois
Ludwig
L
Rouschop
Kasper M A
KM
Chiu
Roland K
RK
Li
Younan
Y
Paesmans
Kim
K
Lambin
Philippe
P
Lammering
Guido
G
Wouters
Bradly G
BG
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
C410723:epidermal growth factor receptor VIII; D066246:ErbB Receptors; D004318:Doxycycline