title: Co-administration of NVP-AEW541 and dasatinib induces mitochondrial-mediated apoptosis through Bax activation in malignant human glioma cell lines.
abstract: Glioblastoma multiforme represents a largely incurable tumor for which novel therapeutic strategies are required. We report the effect of NVP-AEW541, an inhibitor of insulin-like growth factor-I receptor (IGF-IR) kinase activity on growth and signaling in a panel of glioma cell lines. NVP-AEW541 blocked phosphorylation of IGF-IR in a dose- and time-dependent manner and inhibited proliferation and clonogenicity with median effective concentrations of 2.5-10 microM. NVP-AEW541 also induced loss of mitochondrial membrane potential and release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria. Because concentrations of NVP-AEW541 required to significantly inhibit glioma cell viability and downstream signaling also inhibited non-neoplastic astrocytes, we questioned whether differential efficacy could be enhanced by combination with inhibition of other tyrosine kinases dysregulated in gliomas. Dasatinib was selected as a combination agent based on its distinct inhibitory profile for other relevant signaling targets. Combined treatment with NVP-AEW541 and dasatinib induced significantly more apoptosis than either agent alone in glioma cells, but not non-neoplastic astrocytes, and synergistically inhibited clonogenic survival. Mechanistic studies indicated that combination of NVP-AEW541 and dasatinib significantly reduced pERK and pAkt and markedly increased AIF release, Bax oligomerization and loss of mitochondrial potential compared to each agent alone. Overexpression of Bcl-2 and Akt significantly attenuated NVP-AEW541 and dasatinib-induced Bax activation and cell death. Our data indicate that activation of Bax plays a critical role in mediating NVP-AEW541 and dasatinib-induced apoptosis, and suggest the potential value of combining IGFR inhibition with other classes of tyrosine kinase inhibitors to potentiate therapeutic efficacy.
authors.affiliation: Department of Neurosurgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15201, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Premkumar
authors.forename: Esther P
authors.initials: EP
authors.lastname: Jane
authors.forename: Ian F
authors.initials: IF
authors.lastname: Pollack
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D000069439:Dasatinib; D004357:Drug Synergism; D005455:Fluorescent Antibody Technique; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology*; D011758:Pyrroles / Q000008:administration & dosage / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013844:Thiazoles / Q000008:administration & dosage / Q000494:pharmacology*; D014162:Transfection; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: C494826:BAX protein, human; D018797:Cell Cycle Proteins; C501177:NVP-AEW541; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011758:Pyrroles; D013844:Thiazoles; D051028:bcl-2-Associated X Protein; D000069439:Dasatinib