Inhibition of epidermal growth factor receptor signaling protects human malignant glioma cells from hypoxia-induced cell death.
Epidermal growth factor receptor (EGFR) signaling has become an important target for drug development because EGFR signaling enhances tumor cell proliferation, migration, and invasion and inhibits apoptosis. However, the results of clinical trials using EGFR inhibitors in patients with solid tumors have been disappointing. Here, we report a protective effect of the EGFR inhibitors AG1478 and PD153035 against cell death induced by acute hypoxia, which contrasts with their proapoptotic effects under normoxia. Under hypoxic conditions, both agents reduced glucose consumption, delayed ATP depletion, and preserved the mitochondrial membrane potential. Exposure either to hypoxia or the EGFR inhibitors under normoxic conditions resulted in the dephosphorylation of ribosomal protein S6, a player in the energy and nutrient-sensing pathway governed by mammalian target-of-rapamycin (mTOR). Combined inhibition of phosphatidylinositol 3'-kinase (PI3K) and extracellular signal-regulated kinase-1/2 (ERK1/2) mimicked the protective effects of EGFR inhibition on hypoxia-induced cell death and protein S6 dephosphorylation. These results caution that therapies targeting EGFR signaling pathways can protect tumor cells from acute hypoxia.
Department of Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, School of Medicine, Tübingen, Germany. joachim.steinbach@uni-tuebingen.de
Joachim P
JP
Steinbach
Andrea
A
Klumpp
Hartwig
H
Wolburg
Michael
M
Weller
D000255:Adenosine Triphosphate / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia; D004261:DNA Replication / Q000187:drug effects; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D005910:Glioma / Q000188:drug therapy / Q000473:pathology*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011799:Quinazolines; D015398:Signal Transduction / Q000187:drug effects*; D020032:Tyrphostins / Q000494:pharmacology
D000081082:Phosphoinositide-3 Kinase Inhibitors; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; D000255:Adenosine Triphosphate; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D005947:Glucose