Isocitrate dehydrogenase 1 mutant R132H sensitizes glioma cells to BCNU-induced oxidative stress and cell death

• Published in: Apoptosis (London) 2013-11, Vol.18 (11), p.1416-1425
• Main Authors: Mohrenz, Isabelle Vanessa, Antonietti, Patrick, Pusch, Stefan, Capper, David, Balss, Jörg, Voigt, Sophia, Weissert, Susanne, Mukrowsky, Alicia, Frank, Jan, Senft, Christian, Seifert, Volker, von Deimling, Andreas, Kögel, Donat
• Format: Article
• Language: English
• Subjects: Aminooxyacetic Acid - pharmacology; Antineoplastic Agents, Alkylating - pharmacology; Apoptosis; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cancer Research; Carmustine - pharmacology; Cell Biology; Cell death; Cell Death - drug effects; Cell Line, Tumor; Dacarbazine - analogs & derivatives; Dacarbazine - pharmacology; Dehydrogenase; Drug Resistance, Neoplasm - drug effects; Drug Resistance, Neoplasm - genetics; Enzyme Inhibitors - pharmacology; Gene Expression Regulation, Neoplastic; Glutamine - deficiency; HEK293 Cells; Humans; Isocitrate Dehydrogenase - antagonists & inhibitors; Isocitrate Dehydrogenase - genetics; Isocitrate Dehydrogenase - metabolism; Mortality; Mutants; Mutation; Oncology; Original Paper; Oxidative Stress; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Signal Transduction; Virology
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1007/s10495-013-0877-8

Isocitrate dehydrogenase 1 (IDH1) decarboxylates isocitrate to α-ketoglutarate (α-KG) leading to generation of NADPH, which is required to regenerate reduced glutathione (GSH), the major cellular ROS scavenger. Mutation of R132 of IDH1 abrogates generation of α-KG and leads to conversion of α-KG to 2-hydroxyglutarate. We hypothesized that glioma cells expressing mutant IDH1 have a diminished antioxidative capacity and therefore may encounter an ensuing loss of cytoprotection under conditions of oxidative stress. Our study was performed with LN229 cells stably overexpressing IDH1 R132H and wild type IDH1 or with a lentiviral IDH1 knockdown. Quantification of GSH under basal conditions and following treatment with the glutathione reductase inhibitor BCNU revealed significantly lower GSH levels in IDH1 R132H expressing cells and IDH1 KD cells compared to their respective controls. FACS analysis of cell death and ROS production also demonstrated an increased sensitivity of IDH1-R132H-expressing cells and IDH1 KD cells to BCNU, but not to temozolomide. The sensitivity of IDH1-R132H-expressing cells and IDH1 KD cells to ROS induction and cell death was further enhanced with the transaminase inhibitor aminooxyacetic acid and under glutamine free conditions, indicating that these cells were more addicted to glutaminolysis. Increased sensitivity to BCNU-induced ROS production and cell death was confirmed in HEK293 cells inducibly expressing the IDH1 mutants R132H, R132C and R132L. Based on these findings we propose that in addition to its established pro-tumorigenic effects, mutant IDH1 may also limit the resistance of gliomas to specific death stimuli, therefore opening new perspectives for therapy.