title: BH3 mimetics reactivate autophagic cell death in anoxia-resistant malignant glioma cells.
abstract: Here, we investigated the specific roles of Bcl-2 family members in anoxia tolerance of malignant glioma. Flow cytometry analysis of cell death in 17 glioma cell lines revealed drastic differences in their sensitivity to oxygen withdrawal (<0.1% O(2)). Cell death correlated with mitochondrial depolarization, cytochrome C release, and translocation of green fluorescent protein (GFP)-tagged light chain 3 to autophagosomes but occurred in the absence of caspase activation or phosphatidylserine exposure. In both sensitive and tolerant glioma cell lines, anoxia caused a significant up-regulation of BH3-only genes previously implicated in mediating anoxic cell death in other cell types (BNIP3, NIX, PUMA, and Noxa). In contrast, we detected a strong correlation between anoxia resistance and high expression levels of antiapoptotic Bcl-2 family proteins Bcl-xL, Bcl-2, and Mcl-1 that function to neutralize the proapoptotic activity of BH3-only proteins. Importantly, inhibition of both Bcl-2 and Bcl-xL with the small-molecule BH3 mimetics HA14-1 and BH3I-2' and by RNA interference reactivated anoxia-induced autophagic cell death in previously resistant glioma cells. Our data suggest that endogenous BH3-only protein induction may not be able to compensate for the high expression of antiapoptotic Bcl-2 family proteins in anoxia-resistant astrocytomas. They also support the conjecture that BH3 mimetics may represent an exciting new approach for the treatment of malignant glioma.
authors.affiliation: Department of Neurosurgery, Johann Wolfgang Goethe University Clinics, Frankfurt, Main, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hetschko
authors.forename: Valerie
authors.initials: V
authors.lastname: Voss
authors.forename: Christian
authors.initials: C
authors.lastname: Senft
authors.forename: Volker
authors.initials: V
authors.lastname: Seifert
authors.forename: Jochen H M
authors.initials: JH
authors.lastname: Prehn
authors.forename: Donat
authors.initials: D
authors.lastname: Kögel
mesh_terms: D001549:Benzamides / Q000494:pharmacology*; D001578:Benzopyrans / Q000494:pharmacology*; D040761:Biomimetic Materials / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008856:Microscopy, Fluorescence; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009570:Nitriles / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism*; D034622:RNA Interference / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000187:drug effects / Q000378:metabolism; D051020:bcl-X Protein / Q000187:drug effects / Q000378:metabolism
chemical_list: C474172:3-iodo-5-chloro-N-(2-chloro-5-((4-chlorophenyl)sulphonyl)phenyl)-2-hydroxybenzamide; C494826:BAX protein, human; C494811:BCL2L1 protein, human; D001549:Benzamides; D001578:Benzopyrans; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; D020169:Caspases