Overexpression of deletion-mutant epidermal growth factor receptor is associated with altered genotoxic stress-provoked p53 mRNA induction in a humanglioblastoma cell line
Me. Halatsch et al., Overexpression of deletion-mutant epidermal growth factor receptor is associated with altered genotoxic stress-provoked p53 mRNA induction in a humanglioblastoma cell line, ANTICANC R, 21(1A), 2001, pp. 189-195
A distinct 801-bp deletion mutation of the epidermal growth factor receptor
(EGFR) gene is frequently present in primary glioblastoma multiforme (GBM)
, confers enhanced tumorigenicity in vivo and is prognostic of a shorter in
terval to clinical relapse. This study sought to investigate whether overex
pression of deletion-mutant (Delta) EGFR affects genotoxic stress-provoked
mRNA inductions of p53 and murine double minute 2 (MDM2), two other genes s
trongly involved in the pathogenesis of GBM. In a set of human wild-type (w
t) p53 CBM cell lines (U-87MG and U-87MC.Delta EGFR) that exclusively diffe
r in EGFR expression (endogenous wt EGFR expression and exogenous Delta EGF
R overexpression, respectively), ultraviolet (UV) light irradiation-mediate
d EGFR, p53 and MDM2 genotoxic stress-provoken mRNA inductions were assesse
d by semiquantitative reverse transcription-polymerase chain reaction (RT-P
CR) and densitometry of electrophoretically separated and stained RT-PCR pr
oducts. Although baseline (at 0 J/m(2)) p53 mRNA expression in U-87MG.Delta
EGFR was 42-fold reduced, maximum p53 induction (at 8 J/m(2)) amounted to
130% compared to U-87MG. Thus, ultimate UV light-mediated p53 mRNA inductio
n was 131.5-fold in U-87MG.Delta EGFR and 2.8-fold in U-87MG. In contrast,
neither wt/Delta EGFR not MDM2 mRNA expressions were significantly inducibl
e, and MDM2 mRNA profiles were essentially the same among U-87MG and U-87MG
.Delta EGFR. These data suggest that in human GBM overexpression of Delta E
GFX is associated with differential genotoxic stress-provoked p53 mRNA indu
ction whereas MDM2 mRNA expression is apparantly not directly affected by E
GFR status.