bluuebunny/crossref_metadata_2025_split huggingface dataset:
CBMT-12. FOCAD LOSS IMPACTS MICROTUBULE ASSEMBLY, G2/M PROGRESSION AND PATIENT SURVIVAL IN ASTROCYTIC GLIOMAS
Authors: Brand Frank , Förster Alisa , Kosfeld Anne , Bucher Martin , Thomé Carina , Raab Marc , Westphal Manfred , Pietsch Torsten , von Deimling Andreas , Reifenberger Guido , Claus Peter , Hentschel Bettina , Weller Michael , Weber Ruthild 
Published: November 2019

Abstract
In search of novel genes associated with glioma pathogenesis, we have previously shown that KIAA1797/FOCAD is frequently deleted in malignant gliomas and that the encoded focadhesin functions as a tumor suppressor impacting proliferation and migration of glioma cells in vitro and in vivo. Here, we examine an association of FOCAD copy number loss with overall survival of patients with astrocytic gliomas, and address the molecular mechanisms that govern the suppressive effect of focadhesin on glioma growth. FOCAD loss was associated with inferior outcome in patients with isocitrate dehydrogenase 1 or 2 (IDH)-mutant astrocytic gliomas of WHO grades II-IV. Multivariate analysis considering age at diagnosis, IDH mutation and MGMT promoter methylation status confirmed FOCAD loss as a prognostic factor for overall survival. Using a yeast two-hybrid screen and pull-down assays, we identified tubulin beta-6 and other tubulin family members as novel focadhesin-interacting partners. We demonstrate that tubulins and focadhesin co-localize at the centrosome and that focadhesin is enriched in proximity to centrioles. Focadhesin is recruited to microtubules via its interaction partner SLAIN motif family member 2 and reduces microtubule assembly rates, possibly explaining why focadhesin decreases cell migration. During the cell cycle, focadhesin levels peak in G2/M phase and influence time-dependent G2/M progression possibly via polo like kinase 1 phosphorylation, providing an explanation for focadhesin-dependent cell growth reduction. We conclude that FOCAD loss may promote biological aggressiveness and worsen clinical outcome of diffuse astrocytic gliomas by enhancing microtubule assembly and accelerating G2/M phase progression.
CBMT-19. THE ALTERNATIVE LENGTHENING OF TELOMERE (ALT) MECHANISM PROVIDES COLLATERAL SENSITIVITY TO LETHAL TELOMERIC FUSION INDUCED BY TRAPPING PARP INHIBITORS
Authors: Mukherjee Joydeep , Dalle-Ore Cecelia , Johanessen Tor-Christian , Pandita Ajay , Ohba Shigeo , Cahill Daniel , Pieper Russell O 
Published: November 2019

Abstract
A subset of human tumors, including all IDH1-mutant astrocytomas, use a homologous recombination-based alternative lengthening of telomere (ALT) pathway to resolve telomeric dysfunction in the absence of TERT. Because ALT is not used by normal cells, targeting of the process may provide new therapeutic options for patients with ALT-dependent tumors. We here report that reliance on the ALT mechanism makes tumors collaterally hypersensitive to clinically-available trapping PARPi (t-PARPi). Specifically we noted that astrocytoma cells dependent on the ALT-mechanism (IDH1-mutant and ATRX-deficient genetically-modified human astrocytes and MGG119 PDX) were significantly more sensitive to trapping PARPi than matched ALT-independent isogenic ATRXWT astrocytes and MGG152 PDX cells, respectively) both in vitro and in vivo. Surprisingly this hypersensitivity was not associated with BRCA-ness, the extent of PARP inhibition, or with t-PARPi-created genomic DNA damage as is the case in most PARPi-sensitive populations. Rather the enhanced activity of t-PARPi in ALT-dependent cells was associated with a novel t-PARPi-induced, lethal telomere fusion. Furthermore, the extent of chromosomal fusion was proportional to the PARP-trapping ability of the five PARP inhibitors tested, and could be prevented by exogenous expression of TERT, which eliminated reliance on ALT but did not alter levels of PARPi-induced genomic DNA damage. The extent of tPARPi-induced telomeric fusion in ALT-dependent cells, which could be directly measured in small amounts of DNA using a q-PCR approach, was also directly proportional to tPARPi-induced cell death in vitro and to prolonged survival of tumor-bearing mice in vivo. These results therefore identify clinically available tPARPi as a new treatment modality for a select and easily genetically definable group of ALT tumors, and also define telomeric fusion as a biomarker of drug action in these tumors.
CBMT-29. PROMOTING FATTY ACID STORAGE BY DIACYLGLYCEROL-ACYLTRANSFERASE 1 PROTECTS GLIOBLASTOMA AGAINST OXIDATIVE STRESS AND MAINTAINS LIPID HOMEOSTASIS FOR RAPID TUMOR GROWTH
Authors: Cheng Xiang , Geng Feng , Zhong Yaogang , Tian Zhihua , Pan Meixia , Cheng Chunming , Horbinski Craig , Mo Xiaokui , Han Xianlin , Guo Deliang 
Published: November 2019

Abstract
Fatty acids are essential building blocks and energy substrates of lipids in cells. They constitute the major structural components of membrane lipids, i.e., glycerophospholipids and sphingolipids, and also serve as an important energy resource. Whereas excess fatty acids or dysregulation of fatty acid metabolism causes lipotoxicity, leading to severe cell damage. We previously identified that lipid metabolism is dramatically altered in glioblastoma (GBM), especially fatty acid synthesis, which is greatly elevated in various types of cancers. However, how tumor cells prevent excessive fatty acids accumulation from inducing lipotoxicity has rarely been studied. We recently identified that GBM greatly upregulates diacylglycerol-acyltransferase 1 (DGAT1) to direct excess fatty acids into triglycerides and lipid droplets to prevent oxidative stress. Inhibiting DGAT1 disrupts lipid homeostasis and shifts excessive fatty acids moving into mitochondria for oxidation, resulting in a high level of reactive oxygen species (ROS), mitochondrial damage, cytochrome c release and apoptosis. Inhibiting carnitine palmitoyltransferase to reduce fatty acids shuttling into mitochondria significantly decreases ROS and rescues cell death caused by DGAT1 inhibition. Xenograft models show that genetic or pharmacological inhibition of DGAT1 blocks lipid droplet formation, induces tumor cell apoptosis and markedly suppresses GBM tumor growth. Together, our study demonstrates that DGAT1 upregulation protects GBM from oxidative damage and maintains lipid homeostasis by facilitating excess fatty acids storage. Our data further show that targeting DGAT1 specifically induces lipotoxicity in tumor cells, while sparing normal brain, which is a very promising therapeutic strategy antagonizing GBM and has a high potential to shift current paradigm in treating GBM.
CBMT-32. EGFR SUPPRESSES p53 FUNCTION THROUGH DNA-PKcs BINDING TO p53: NOVEL CROSSTALK BETWEEN EGFR AND TP53 IN GLIOBLASTOMA
Authors: Ding Jie , Li Xiaolong , Zhang Chen , Gao Feng , Wu Shaofang , Wasylishen Amanda , Baggerly Keith , Lozano Guillermina , Koul Dimpy , Yung Alfred 
Published: November 2019

Abstract
Comprehensive analysis of the TCGA Glioblastoma database has identified 3 prognostically relevant subgroups (Proneural, Classical and Mesenchymal). Interestingly, it has also revealed a near mutual exclusivity of EGFR amplification and TP53 mutations. There are only a few tumors with both amplified EGFR and mutant TP53. We decided to investigate the functional relationship between EGFR and TP53 relative to tumorigenesis and tumor proliferation. We selected from our molecularly characterized GSC bank a series of EGFR amplified+TP53wt/TP53mut lines for this study. Here we report that EGFR amplification overrides the effect of p53wt but co-regulates tumorigenesis with TP53R175H mutation. We show that CRISPR EGFR knockout in TP53wt cells leads to complete loss of cell growth suggesting that EGFR is essential for cell survival, providing growth signal and suppression of p53wt function. We further show that EGFR induces physical binding between p53wt and DNA-PKcs, which suppresses p53wt by inhibiting p53 phosphorylation at S15. The knockdown of DNA-PKcs restores p53wt anti-tumor function. In contrast, GSC262 harboring TP53R175H mutation is the only GSC that survives after EGFR knockout, suggesting that this specific mutation has a gain of function (GOF) to sustain growth without EGFR. This is confirmed by dual knockout of EGFR and TP53R175H showing no surviving cells. Further investigation shows both EGFR and p53R175H induce tumor glycolysis, the major energy metabolism and heightened growth signal for this group. We further show that EGFR mediated suppression of p53R175H is through DNA-PKcs binding to p53R175H and reduced S15 phosphorylation. Taken together, this study reveals 1) EGFR amplification is essential for tumor growth in TP53wt GSCs; 2) novel crosstalk between EGFR and p53 through DNA-PKcs. 3) EGFR suppresses p53wt function by providing the energy required for tumor growth through inducing glycolysis, and 4) TP53R175H is a GOF mutation that sustains life without EGFR by inducing glycolysis.
CSIG-04. PAN-RTK INHIBITION OF sLRIG1 MEDIATES AXL DOWNREGULATION IN GLIOBLASTOMA
Authors: Neirinckx Virginie , Hau Ann-Christin , Schuster Anne , Fritah Sabrina , Chevigné Andy , Schmidt Mirko H , Niclou Simone 
Published: November 2019

Abstract

INTRODUCTION
Aberrant regulation of receptor tyrosine kinase (RTK) activity is characteristic of Glioblastoma (GBM). However, RTK-based targeted therapies have been largely unsuccessful in GBM patients, partially due to the complexity and redundance of RTK signaling. LRIG1 (Leucine-rich Repeats and ImmunoGlobulin-like domains 1) is an important endogenous inhibitor of epidermal growth factor receptor (EGFR) during health and disease, however its mechanism of action is poorly understood. We previously showed that the soluble form of LRIG1 potently inhibits GBM growth in vivo, irrespective of EGFR expression level and status, suggesting the involvement of other RTKs. Here, we aimed to shed light on the molecular mechanisms underlying its anti-cancer activity.

MATERIAL AND METHODS
We generated a recombinant human soluble LRIG1 protein (rh-sLRIG1) by expressing LRIG1 ectodomain in insect cells via baculovirus infection and subsequent His-tag purification. rh-sLRIG1 was used to treat patient-derived GBM stem-like cells, classical GBM cell lines and patient-derived 3D tumor organoids. Using different cell-based assays, cell proliferation, invasion, cell morphology, as well as protein expression and protein-protein interactions were investigated.

RESULTS
We find that recombinant sLRIG1 efficiently reduced proliferation, invasion and viability of GBM cells and patient-derived organoids, and modulated cytoskeleton proteins and cell shape. In line with previous data, the effect of recombinant sLRIG1 was independent of EGFR expression. Interestingly sLRIG1 impacted multiple RTKs including AXL, by direct protein downregulation, while EGFR expression was not affected. At the molecular level, we find that sLRIG1 interfereed with AXL dimerization, while no protein interaction with EGFR was detected.

CONCLUSION
We identify AXL as a novel LRIG1 target and provide evidence that sLRIG1-mediated RTK downregulation requires direct protein-protein interaction. These data pave the way for a potential therapeutic application of recombinant sLRIG1 in the inhibition of growth factor signaling in GBM.
CSIG-10. ROLE OF c-Met/β1 INTEGRIN COMPLEX IN THE ESTABLISHMENT OF BRAIN METASTASES
Authors: Wadhwa Harsh , Lau Darryl , Chandra Ankush , Nguyen Alan , Shah Sumedh , Spatz Jordan , Safaee Michael , Sudhir Sweta , Patel Akshar , Cheng Justin , Aghi Manish 
Published: November 2019

Abstract

INTRODUCTION
Metastases cause 90% of human cancer deaths. The metastatic cascade involves five steps: invasion, intravasation, extravasation, colonization, and proliferation. While individual mediators of these processes have been investigated, their interactions remain undefined. We previously demonstrated increased formation of a structural complex between receptor tyrosine kinase c-Met and β1 integrin in metastases compared to primary tumors. We used novel cell culture models and in vivo assays to define the role of this complex in individual steps of the metastatic cascade.

METHODS
The iDimerize heterodimer system was inserted into MDA-MB-231 breast adenocarcinoma cells, allowing c-Met/β1 heterodimerization induction via A/C heterodimerizer treatment. Scratch assays and novel transwell assay modifications were used to measure migration, invasion, intravasation, and extravasation. Proximity ligation assay was performed to measure c-Met/β1 complex. Nanostring panel was used to transcriptionally profile cells.

RESULTS
c-Met/β1 complex induction promotes breast cancer invasion (p< 0.001), migration (p< 0.05), intravasation (p< 0.01), and adhesion to the vessel wall (p< 0.01). However, it does not increase extravasation in culture or in vivo. These effects may be driven by the ability of c-Met/β1 to increase mesenchymal character (p< 0.05) and stem cell population (p< 0.001). Nanostring analysis revealed upregulated Wnt and hedgehog pathways after c-Met/β1 complex induction, particularly WNT7B (p< 0.05). OS2966, an antibody preventing c-Met/β1 binding, decreased invasion (p< 0.05), intravasation (p< 0.05), and mesenchymal morphology (p< 0.001) and gene expression (p< 0.001). Brain- and bone-seeking breast cancer cells have higher c-Met/β1 complex than controls (p< 0.05) and preferentially adhere to tissue-specific matrix (p< 0.01).

CONCLUSIONS
The c-Met/β1 complex drives breast cancer cell intravasation. While extravasation is not affected by the complex, preferential affinity for tissue-specific matrix enables the c-Met/β1 complex to drive breast cancer metastases to brain and bone. Pharmacological targeting of the complex may prevent metastases, particularly to the brain and bone.
CSIG-15. INHIBITION OF THE bHLH TRANSCRIPTIONAL NETWORKS BY A MUTATED E47 PROTEIN LEADS TO A STRONG ANTI-GLIOMA ACTIVITY IN VITRO AND IN VIVO
Authors: Koch Marilin , Czemmel Stefan , Lennartz Felix , Beyeler Sarah , Przystal Justyna , Govindarajan Parameswari , Canjuga Denis , Neumann Manfred , Rizzu Patrizia , Tatagiba Marcos , Nahnsen Sven , Heutink Peter , Raineteau Olivier , Tabatabai Ghazaleh 
Published: November 2019

Abstract

OBJECTIVE
The transcription factor E47 heterodimerizes with helix-loop-helix (HLH) and basic helix-loop-helix transcription (bHLH) factors like ID-1 and Olig2 that are overexpressed in glioblastoma. A dominant-negative variant of the E47 (dnE47) lacking the nuclear translocation signal, leads to cytoplasmatic sequestration of HLH and bHLH transcription factors. Here, we investigated combinations of dnE47-mediated inhibition of the bHLH transcriptional network with temozolomide and irradiation and explored the underlying molecular mechanisms.

METHODS
Long-term and stem cell glioma lines were transduced with a Doxycycline-inducible dnE47 lentivirus. Functional characterizations included immunocytochemistry, immunoblots, cytotoxicity and clonogenicity assays in vitro and latency until the onset of symptoms in vivo. CAGE and RNASeq were conducted for analyzing the dnE47-induced molecular profile.

RESULTS
The induction of dnE47 led to cytoplasmatic sequestration of HLH/bHLH transcription, reduced proliferation, increased cytotoxicity and reduced clonogenic survival in vitro and a prolonged latency until the onset of neurological symptoms in vivo. CAGE and RNASeq data revealed alterations in several cancer-relevant pathways.

CONCLUSIONS
A dnE47-mediated inhibition of the bHLH transcription network induced actionable molecular alterations in glioma cells that could be exploited for the design of novel therapies.
CSIG-19. CYTOMEGALOVIRUS INFECTION LEADS TO NF-kB DEPENDENT UPREGULATION OF c-MET AND MGMT IN GLIOBLASTOMA AND RESISTANCE TO TEMOZOLOMIDE IN VIVO
Authors: Zdioruk Mykola , Krenzlin Harald , Oskar Nowicki M , Cook Charles H , Chiocca Ennio , Lawler Sean 
Published: November 2019

Abstract

INTRODUCTION
Cytomegalovirus (CMV), a member of the betaherpesvirinae subfamily widespread in human populations has been reported to be detectable in glioblastoma (GBM). We have recently shown that CMV latent infection promotes GBM growth in a mouse model. The mechanisms involved are not well-defined and treatment responses have not been evaluated.

METHODS
To investigate the effects of CMV on GBM cells we performed an RNAseq study. Differentially expressed genes were identified and validated in vitro and in vivo.

RESULTS
RNAseq analysis showed multiple alterations induced by CMV infection of GBM cells including significant upregulation of c-MET (8.2 log2 fold change) and MGMT (3.9 log2 fold change) transcripts after CMV infection. c-MET is a tyrosine kinase receptor known to promote GBM growth, and MGMT expression leads to resistance to the alkylating agent temozolomide (TMZ). These findings were validated in vitro in both mouse and human GBM cells, and shown to be dependent on CMV-induced upregulation of NF-kB by siRNA knockdown of the essential RelA NF-kB subunit. The c-MET co-receptor CD44 was also upregulated suggesting a role for the c-MET signalling axis in CMV induced tumor progression. CMV-infected tumor cells were resistant to TMZ treatment as expected due to MGMT upregulation. Treatment of our murine GBM model with TMZ led to a significant increase in survival in control mock-infected mice (median survival 38 days control, 48 days TMZ), whereas the CMV infected mice did not respond (median survival 35 days control, 35 days TMZ; p value between TMZ treated groups = 10–4).

CONCLUSIONS
Our results define novel and relevant mechanisms by which CMV may influence both GBM growth and resistance to treatment. Further therapeutic and mechanistic studies are underway to investigate these pathways in the context of CMV in GBM. These data support further study of CMV targeting in GBM.
CSIG-23. NOTCH ACTIVATION INDUCED BY HSV-1 ENCODED miRNA-H16 SENSITIZES oHSV-TREATED TUMORS TO NOTCH INHIBITOR
Authors: Otani Yoshihiro , Young Yoo Ji , Chao Samantha , Liu Joseph , Cristina Jaime-Ramirez Alena , Jin Lee Tae , Hurwitz Brian , Yan Yuanqing , Dai Hongsheng , Glorioso Joseph C , Caligiuri Michael A , Yu Jianhua , Kaur Balveen 
Published: November 2019

Abstract

INTRODUCTION
Glioblastomas (GBMs) are resistant to traditional therapies, and new treatment is urgently needed. NOTCH signaling is highly activated in glioma and activated NOTCH signaling is associated with increased tumor growth and therapeutic resistance. Effect of oncolytic virus therapy on NOTCH signaling activation has not been reported to our knowledge.

METHODS
Western blotting, real time Q-PCR, reporter assay, and bioluminescence mice imaging were used to evaluate oHSV-mediated activation of NOTCH signaling. High throughput analysis of HSV-1-encoded microRNAs and genes were performed to identify the activator of NOTCH signaling, and in silico analysis, 3’ untranslated region (3’UTR) assay, and immunoprecipitation were used to uncover the down-stream signaling. Anti-tumor efficacy of NOTCH inhibitor, gamma-secretase inhibitor (GSI) combined with oHSV was evaluated using intracranial glioma-bearing mouse xenografts.

RESULTS
oHSV infection induced NOTCH activity in glioma PDX cells. High throughput analysis uncovered this to be due to HSV-1-encoded miR-H16 (miR-H16). 3’UTR analysis of Factor Inhibiting HIF-1 (FIH-1) indicated miR-H16 directly target FIH-1 and repress its protein expression. Immunoprecipitation analysis also uncovered that FIH-1 reduction liberated Mild bomb 1 (Mib1) from FIH-1 mediated sequestration, permitting it to activate NOTCH signaling by ubiquitination of NOTCH ligands. Forced expression of either antago-miR-H16 or FIH-1 attenuated the oHSV-induced NOTCH activation. Furthermore, oHSV therapy-induced activation of NOTCH signaling sensitized tumors to GSI, resulting in significantly improved therapeutic response to oHSV therapy and prolonged the survival in several intracranial GBM xenografts.

CONCLUSION
In this study, we identified the mechanism of oHSV therapy-mediated activation of NOTCH signaling, and showed the therapeutic benefit of combining oHSV with GSI.
CMET-01. IMMUNE CHECKPOINT INHIBITORS FOR NON-SMALL CELL LUNG CANCER WITH BRAIN METASTASIS: THE ROLE OF GAMMA KNIFE RADIOSURGERY
Authors: Ho Lee Min , Cho Kyung-Rae , Lee Jung-Il 
Published: November 2019

Abstract

PURPOSE
Immune checkpoint inhibitors (ICIs) are approved for the treatment of non-small cell lung cancer (NSCLC), but the safety and efficacy of the combined treatment with ICIs and gamma knife radiosurgery (GKS) remain undefined.

METHODS
We retrospectively reviewed the medical records of patients with brain metastases from NSCLC who were treated with ICIs between January 2015 and December 2017 at our institute. Of the 134 patients identified, 77 who were assessable for brain responses were categorized into three groups based on the medication administered and GKS: Group A, ICI alone; Group B, ICI with concurrent GKS within 14 days; and Group C, ICI with non-concurrent GKS.

RESULTS
The median follow-up duration after the diagnosis of brain metastases was 19.1 (range, 1–68.7) months. At the last follow-up, 48 patients (62.3%) died. The overall survival was shorter in Group A than in Groups B and C (P=0.001). There were no statistically significant differences in the intracranial disease progression-free survival (P=0.514), local progression-free survival (P=0.358), and complication rates among the three groups. Twelve patients presented with leptomeningeal seeding (LMS) during follow-up. There was a significant difference in the LMS-free duration from the time of administering ICIs (P=0.011) and the diagnosis of metastasis (P< 0.001).

CONCLUSION
GKS in combination with ICI showed no favorable overall survival outcome in the treatment of brain metastasis from NSCLC. However, GKS with ICI did not increase the risk of complications. Furthermore, compared with ICI alone, GKS with ICI may be associated with a reduced incidence of LMS.