CS-36 * IkappaB ZETA OVEREXPRESSION DRIVES HUMAN GLIOMA RESISTANCE TO NECROPTOSIS
摘要
BACKGROUND: The objective was to analyze the role of IkappaB-zeta in the cell death resistance and growth of glioblastomas. METHODS: The CNV, mRNA and protein expression of NFKBIZ/IKB-zeta were assessed in low grade and high grade glioma samples from the TCGA, the Rembrandt and proprietary cohorts of tumors, totaling 1195 samples. Data were correlated to histological grade and patient survival. IKBzeta expression was knocked down using inducible sh-RNA technology in GBM cultures, and clonogenic assays, MTT counts, caspase activation and LDH release assays, Western blotting, FACS and DNA damage assays and in situ xenograft models of malignant gliomas in nude mice were analyzed in these conditions. IKB-zeta interacting proteins were defined using immunoprecipitation, mass spectroscopy and proximity ligation assays, and protein localization was identified using selective compartmental protein extractions methods. RESULTS: NFKBIZ was amplified in 2.3% of LGG and 10% of GBM (P < 0.0001, Chi-Sqare), and its mRNA and protein expression increased with grade. NFKBIZ mRNA expression significantly associated with poor survival in a multivariate continuous Cox model (465 tumors) that also included patient age and molecular subclass (classical, mesenchymal, neural, proneural) : p = 0.030, HR: 1.12, 95%-CI: 1.01-1.24. IKB-zeta knock-down allows the translocation of STAT proteins to the mitochondria, induces a massive necroptotic cell death through a transcription-independent, TNF-related mechanism, and prevents tumor growth in xenograft models of human GBM. CONCLUSIONS: NFKBIZ is overexpressed in malignant gliomas, protects them from necroptotic cell death via a transcription-independent mechanism and constitutes a promising therapeutic target for these tumors.