English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

vi45 NEURO-ONCOLOGY • NOVEMBER 2016 CSIG-20. IDENTIFICATION OF A NAMPT-E2F2-ID1 SIGNALING AXIS IN GLIOBLASTOMA Amit  Gujar1, Alice  Turski1, Son  Le2, Diane  Mao1, David  Dadey3, Diane Aum1, Jingqin Luo4, Dennis Hallahan3, David Tran2, Hiroko Yano1 and Albert  Kim1; 1Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO, USA, 2Preston A. Wells, Jr. Center for Brain Tumor Therapy, Gainesville, FL, USA, 3Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA, 4Siteman Cancer Center Biostatistics Core, Washington University School of Medicine, St Louis, MO, USA Emerging evidence shows that nicotinamide adenine dinucleotide (NAD+)dependent signaling plays a critical role in a variety of biological contexts including cancer. The rate-limiting enzyme of the mammalian NAD+ synthesis pathway, nicotinamide phosphoribosyltransferase (NAMPT), governs NAD+-dependent processes by catalyzing production of nicotinamide mononucleotide (NMN), a key NAD+ precursor. However, the role and molecular mechanisms of NAMPT in the biology of human glioblastoma have remained poorly understood. Here, we demonstrate that NAMPT is highly expressed in glioblastoma tumor specimens and patient-derived glioblastoma stem-like cells (GSCs). High NAMPT expression in glioblastoma tumors correlates with poor prognosis in patients. NAMPT inhibition using FK866 as well as RNA interference (RNAi) depleted NAD+ levels in GSCs and substantially decreased GSC self-renewal. Importantly, NAMPT knockdown diminished the in vivo tumorigenicity of GSCs and prolonged the survival of animals in an orthotopic xenograft model. Bioinformatic analysis of RNA-sequencing data derived from FK866-treated GSCs revealed E2F family transcription factor E2F2 as a potential hub of the NAD+-dependent transcriptome. Accordingly, E2F2 knockdown decreased the self-renewal capacity of GSCs. Downstream, we find that E2F2 directly controls the transcription of helix-loop-helix protein inhibitor of differentiation 1 (ID1), a known regulator of self-renewal. Finally, we show that NAMPT promotes radiation resistance of GSCs in culture, highlighting the potential therapeutic relevance of this pathway. The identification of a NAMPT-E2F2-ID1 signaling pathway, which regulates GSC maintenance, has ramifications for the development of novel therapeutic strategies for glioblastoma patients. CSIG-21. CELL DEATH MECHANISMS OF ANTI-TUMOR THIOBARBITURIC ACID COMPOUND FOR CANCERS Sang Lee and James Connor; The Pennsylvania State University College of Medicine, Hershey, PA, USA Previously, we reported that a derivative of thiobarbituric acid compound (CC-I) is an effective agent for chemotherapy resistant gliomas and neuroblastoma. In this study, we studied the mechanism of action of this compound. CC-I induced apoptosis in a dose dependent manner in CCF-STTG1 GBM cell lines, but CC-I induced necrotic cell death in a dose dependent manner in neuroblastoma cells. CC-I exposure was also associated with cell cycle arrest in S and G2/M phase in GBM and neuroblastoma cells. The Human Apoptosis Microarray revealed that tumor necrosis factor (TNF) pathway genes have the greatest changes in gene expression in the CCF-STTG1 cells compared to the vehicle treated cells. Among caspase pathway genes, caspase 10 and caspase 14 but not caspase 3 were over 16 fold induced. Moreover, CC-I activated AKT in a dose and time dependent manner in glioma cells. According to Human Phospho-Kinase array, in addition to the activation of AKT, all three MAPKs (ERK, JNK, p38) were activated by CC-I. While phospho-AKT (S473) increased 2 fold, phospho c-jun (S63) was elevated 38 fold and phospho JNK (p-JNK) (T183/Y185, T221/Y223) was increased 8 fold compared to vehicle treated controls. The western blot and Kinase array data also indicated that CC-I mediated apoptosis is p53 independent, at least in CCF-STTG1 GBM cells. In summary, the present results and our previous findings provide compelling evidence that CC-I induced cell death in GBM cells occur via a TNF-JNK mediated cell death mechanism. CSIG-22. MUTATIONAL HETEROGENEITY OF THE EGFR EXTRACELLULAR DOMAIN PROMOTES AN ONCOGENIC UNTETHERED TRANSITIONAL CONFORMATION AND THE POTENTIAL FOR GREATER THERAPEUTIC TARGETING IN GBM PATIENTS Amy Haseley  Thorne1,2, Laura  Orellana3, Alison  Parisian1,2, Webster  Cavenee2 and Frank  Furnari1,2; 1University of California San Diego, San Diego, CA, USA, 2Ludwig Institute, San Diego, CA, USA, 3Theoretical and Computational Biophysics Laboratory, Science for Life Laboratory, Stockholm, Sweden The epidermal growth factor receptor (EGFR) is both amplified and frequently mutated in glioblastoma (GBM). While downstream inhibition of EGFR signaling through small molecule tyrosine kinase inhibitors (TKIs) has shown little clinical efficacy, monoclonal antibody targeting is proving to be a promising alternative. The monoclonal antibody 806 (mAb806) specifically binds the most common EGFR mutant, EGFRvIII, as well as amplified WTEGFR, but not EGFR expressed at low levels. The selectivity of mAb806 is thought to be due to its targeting a tumor-specific epitope of EGFR which is only accessible as the receptor transitions between an inactive tethered conformation to an active ligand-bound dimer. To address this question, we modeled several point mutations of the EGFR ectodomain (ECD) which naturally occur in GBM patients. Using molecular dynamics simulations we show that G63R and R108K expose the mAb806 epitope by way of their extreme flexibility at the domain I-II hinge region. In vitro analyses of these mutants reveals an increased ability to bind mAb806 in glioma cell lines. Furthermore, these point mutations and others were found to increase tumorigenicity in vivo. Examining downstream signaling pathways revealed similarities in signaling between the ECD deletion mutants EGFRvIII and EGFRvII while the individual point mutants R108K, G63R, A289V and G598V signal similarly to WT-EGFR. We go on to show that although treatment with a TKI before mAb806 increases binding to U87 parental and WT-EGFR expressing cells, and thus will likely prove to have increased toxicity in patients, forcing the kinase domain of EGFR into an active vs. inactive state had surprisingly different effects on mAb806 exposure based on its mutational status. Thus, the ECD mutants may be used as a tool to increase the understanding of how EGFR structure affects function and ultimately oncogenicity. CSIG-23. CYTOPLASMIC RNA STRESS GRANULES: A PUTATIVE TRANSLATIONAL MECHANISM OF mTOR REGULATION IN GLIOBLASTOMA Adrienne Weeks1, Scott Whitehouse1, Aaron Robichaud1, Sameer Agnihotri2, Christian Smith2 and James Rutka2; 1Dalhousie, Halifax, NS, Canada, 2The Hospital for Sick Children, Toronto, ON, Canada We performed RNA immunoprecipitation followed by microarray profiling of mRNAs pulled down by Stress Granule (SG) markers TIAR and G3BP1 in normal and oxidative stress conditions to enrich for mRNA contained in SGs during stress in Glioblastoma cell lines. Interestingly, components of the mTOR Ragulator, RRAGD and LAMTOR were enriched in G3BP1 precipitates in stress conditions. We confirmed localization of RRAGD mRNA to SGs utilizing single molecule RNA FISH in arsenite stressed Glioblastoma cell lines. We therefore hypothesized that perhaps Ragulator mRNAs are sheltered in SG for rapid translation after stress release. We confirmed that protein levels of RRAGD and LAMTOR increase at 25-35 minutes postrelease from arsenite induced stress concomitant with a 50% decrease in SGs. We also observed similar increases in protein levels of other Ragulator components (RRAGA/B/C). This increase differed from protein levels of other mRNAs identified in our screen, which showed no increase in protein levels after stress release (TIAM1, WAVE1/2, FOXK2, FOXN3). The increase in protein levels of the Ragulator complex components remained despite the addition of actinomycin D, suggesting that the increase protein levels are a result of translation of a stabilized cohort of mRNA and not de novo transcription. Interestingly, preliminary data utilizing a mCherry-LAMP construct suggests that mTOR colocalizes to the lysosome at 25-35 minutes post release from stress, a necessary step for mTOR activation. Utilizing Glioblastoma cells that we have engineered to display a delay in SG dissolution, we aim to demonstrate impaired SG release of mRNA results in a shift in the Ragulator protein spike after stress release. Taken together this data suggests a novel translational control mechanism of mTOR activation by SGs. CSIG-24. REGULATION OF Fn14 EXPRESSION BY EGFRvIII-STAT SIGNALING ENHANCES GLIOBLASTOMA CELL INVASION AND SURVIVAL Alison  Roos1, Zachary  Mayo2, Heather  Sonnemann2, Gil  Lambert2, Harshil  Dhruv1, Jeffrey  Winkles3, Michael  Berens1, Nhan  Tran4 and Marya Sabir2; 1TGen, Phoenix, AZ, USA, 2Translational Genomics Institute, Phoenix, AZ, USA, 3University of Maryland, School of Medicine, Baltimore, MD, USA, 4Translational Genomics Research Institute (TGEN), Phoenix, AZ, USA Glioblastoma Multiforme (GBM) is the most common malignant brain tumor in adults. Most GBM patients succumb to the disease less than one-year post diagnosis due to the highly invasive nature of the tumor, which prevents complete surgical resection and gives rise to tumor recurrence. The invasive phenotype also confers radio-and chemoresistant properties to the tumor cells; therefore, there is a need to develop new therapeutics that target drivers of GBM invasion. Amplification of EGFR is observed in over 50% of GBM tumors, of which half concurrently overexpress the variant EGFRvIII, and expression of both receptors confers a worse prognosis. EGFR and EGFRvIII cooperate to promote tumor progression and invasion, in part, through activation of the STAT-signaling pathway. Here we report that GBM cells expressing EGFRvIII show increased expression of a previously