bluuebunny/crossref_metadata_2025_split huggingface dataset:
TMIC-32. IMPACT OF LOW-INTENSITY TRANSCRANIAL DIRECT-CURRENT STIMULATION (TDCS) IN GLIOBLASTOMA
Authors: Das Arabinda , McDonald Daniel G , Yazdani Milad , Welsh Cynthia A , Infinger Libby Kosnik , Vandergrift III William A , Varma Abhay K , Patel Sunil J , Cachia David , Zukas Alicia M , Lindhorst Scott M 
Published: November 2023

Abstract
The prognosis of glioblastoma (GBM) remains poor despite multiple attempts over the years to develop better treatment options for patients with this disease. Various challenges include an immunosuppressive tumor microenvironment, poor knowledge of the neuroimmune system, and the presence of the blood−brain barrier amongst others. To try and overcome some of these barriers, we used a low-intensity non-invasive transcranial direct current stimulation (tDCS) to suppress tumor growth and enhance the immune response in preclinical glioblastoma cell culture and animal model. This study reports for the first time that treatment of GBM and rGBM (recurrent GBM) cells with tDCS (50 mV/mm for 30 min), can modulate the expression of human leukocyte antigen (HLA) class II molecules such as HLA-DR alpha, HLA-DR complex, invariant chain (Ii), and HLA-DM (an important catalyst of the class II-peptide loading). Furthermore, we demonstrated in vivo that tDCS [350 μA (1 x 30 min/day) treatment 7 times (within 14 Days) showed a significant (~30%) decrease in GBM tumor growth in an orthotopic allograft GL261 GBM mouse model (at Day 41). Following tDCS treatment, our results demonstrated the downregulation of Ki-67 in treated tumors. Also, we observed the upregulation of CD38 (M1 macrophages) and CD8+ T cells in treated cells in vivo. Based on our preliminary data from in vitro and in vivo studies, we believe that this study suggests that induction of immune components of the HLA class II pathway by tDCS may be a promising therapeutic strategy for the treatment of human GBM.
TMIC-33. UNDERSTAND AND TARGET ASTROCYTE REACTIVITY IN BRAIN TUMORS TO PREVENT RADIORESISTANCE
Authors: Jeannot Pauline , Berg Tracy , Dawson John , Eliott Richard , Carragher Neil , Pietras Alexander 
Published: November 2023

Abstract
Glioblastoma multiforme (GBM) is the most aggressive type of glioma and deadliest brain tumor. Despite aggressive treatments including surgery, chemo-, and radiotherapy, tumors invariably recur as incurable lesions, and the median survival is approximately 15 months after diagnosis. Recurrence is tightly linked to tumor cell resistance to ionizing radiation (IR), a feature that in turn is linked to stem cell characteristics of tumor cells. Previous results from our lab indicate that stromal astrocytes respond to IR with a reactive phenotype that in turn promotes therapeutic resistance of neighboring tumor cells. Our objectives were to i) identify pathways involved in IR-induced astrocyte reactivity; ii) identify compounds able to inhibit IR-induced astrocyte reactivity. We used two complementary approaches to meet our objectives. Using an antibody array we found that JNK and ABL pathways were activated following IR in primary human astrocytes. To validate their involvement in the induction of astrocyte reactive phenotype we used an image-based readout combining the changes in the expression of reactivity markers and in the morphology of astrocytes. For the second approach, we used a similar readout to perform an image-based drug screen which aimed to identify compounds able to inhibit IR-induced astrocyte reactivity. The drug libraries used consisted of approved drugs to get candidates with potential for drug repurposing. We identified 20 compounds inhibiting IR-induced astrocyte reactivity and amongst them, 10 are brain-penetrant compounds that could make them good candidates for repurposing in GBM. An in vivo test is now ongoing with 2 of these compounds in a PDGFA/PDGFB-driven mouse model of GBM to validate their efficiency to increase radiosensitivity of the tumor cell by inhibiting astrocyte reactivity
TMIC-34. SKULL-DERIVED MYELOID CELLS AUGMENT T CELL RESPONSES AND SUPPRESS GLIOBLASTOMA GROWTH
Authors: Lad Meeki , Kalistratova Venina , Young Jacob , Gill Sabraj , Saha Atul , Rios Jennifer , Salha Diana , Lui Austin , Aghi Manish 
Published: November 2023

Abstract
While recent studies have implicated the skull marrow as a functional immune reservoir in CNS pathology, its contribution to malignancy remains unexplored. To that end, we transplanted fluorescently-labeled calvarial flaps into syngeneic glioblastoma-bearing mice and cytometrically characterized tumor-infiltrative immune cells, observing a robust population of skull-derived myeloid cells (SDMCs; 40.3% of all intratumoral myeloid cells) in a Balb/C mouse tumor model (CMFDA-stained flaps, 72h). These SDMCs were robust, remaining viable for 3 weeks in an alternative longitudinal model (C57BL/6 mice, GFP+ flaps). As MHCII+ leukocytes were disproportionately enriched among SDMCs (87.9% vs 67.3%, n=3, p=0.012), we interrogated the immunogenicity of these cells through targeted skull ablation, achieved via 13 Gy irradiation of body-shielded mice prior to orthotopic glioblastoma implantation. Indeed, skull-ablated mice had reduced infiltration by antigen-presenting cells than controls (cDCs: 1.1% vs 4.5%, p=0.002; macrophages: 14.4% vs 36.6%, n=10/group, p&lt; 0.001) and 6-fold greater necrosis (67.7% vs 13.5% apoptotic, p&lt; 0.001), suggesting an impaired ability to mount a controlled, adaptive immune response. To clarify the role of SDMCs in mediating secondary immune function, we administered the CXCR4 antagonist AMD3100 between the inner and outer tables of the skull, inhibiting marrow homing signals and promoting myeloid precursor egress (0.26% vs 0.02% of intratumoral myeloid cells, n=10/group, p&lt; 0.001). This yielded cDC2 expansion (10.4% vs 3.0%, p=0.003) and consequent CD4+ T effector memory differentiation (92.3% vs 60.0%, p=0.007). These differences were clinically meaningful, as skull irradiation accelerated tumor growth and attenuated survival compared to controls, while AMD3100 treatment accomplished the opposite (median OS: 17d vs 22d, p&lt; 0.001; 26.5d vs 22d, p=0.006). Concurrent αCD4/CD8/Thy1.2 administration abrogated the therapeutic effect of AMD3100 entirely, confirming the dependency of SDMC-mediated tumor suppression on T cells. Together, our work clarifies the antitumoral role of skull marrow and represents the first-ever therapeutic modulation of this space.
TMIC-35. TUMOR CELL-DERIVED SPERMIDINE ACCELERATES GLIOBLASTOMA PROGRESSION VIA LYMPHOCYTE DEPLETION
Authors: Kay Kristen , Bayik Defne , Wang Zeneng , Miska Jason , Brown J Mark , Hazen Stanley L , Lathia Justin 
Published: November 2023

Abstract
Therapeutic resistance in glioblastoma (GBM) is partly due to a highly immunosuppressive environment resulting in ineffective anti-tumor immune response. This likely underlies the lack of success of immunotherapies that are successful in other cancers; novel ways to target this environment are needed. Naturally occurring polyamines (PAs) have been identified as a putative therapeutic target in other cancers based on their increased presence and correlation to poorer prognosis. Under normal conditions, spermidine (SPD) – a member of the PA family – is critical for cell growth. While PAs are increased in GBM patients, little is known about their impact on GBM growth. In syngeneic immunocompetent mouse glioma models, mass spectrometry revealed that SPD increases in the tumor microenvironment and circulation as compared to non-tumor-bearing mice. We treated the same models with exogenous SPD, which significantly decreased survival. However, in immunocompromised mice, no survival difference was observed, suggesting SPD drives GBM progression through immune interaction. Immune profiling the mouse models treated with SPD showed peripheral reduction of CD4+ and CD8+ T cells. Due to the observed T cell changes, we repeated the exogenous SPD paradigm in RAG1 knockout mice that do not have circulating B/ T cells. Similar to NSG mice, we see no survival difference, indicating that SPD drives GBM by affecting lymphoid cells. To investigate the origin of SPD in our models, we knocked down the rate limiting enzyme of the PA biosynthesis pathway in glioma cells in immunocompetent mice. Mice implanted with knockdown cells showed a robust survival extension, suggesting that tumor cells produce SPD which affects the tumor microenvironment. Ongoing studies are evaluating uptake from the environment on the progression of GBM using pharmacological inhibitors. Understanding the interactions of PAs and the immune response as a whole will allow us to alter the environment to enhance immunotherapeutic efficacy.
TMIC-37. AN ADVANCED PHAGOCYTOSIS GLIOMA THERAPY BASED ON MICROGLIA: INSIGHT FROM AD THERAPY
Authors: Lu Jie , Mou Yonggao 
Published: November 2023

Abstract

INTRODUCTION
Alzheimer's disease (AD) has an inverse correlation with glioma incidence. AD brain present a suppressive environment for glioma initiation and progression caused by amyloid β42 (Aβ42) activation of microglia. However, the underlying mechanisms remain elusive.

METHODS
Public database of patients with AD and brain cancer were collected and analyzed for the correlation between the two distinct diseases. The level of Aβ42 expression was examined by IHC staining in lower-grade glioma (LGG) and higher-grade glioma (HGG). Glioma-bearing mice were applied to evaluate the tumor suppressive effect induced by oligomer Aβ42 (OAβ42) in vivo. The co-culture system was applied to study the mechanism of OAβ42 activated microglia and enhanced tumor cell phagocytosis. RNA sequencing was performed to identify the underlying molecular mechanism involved in OAβ42 potentiated microglial phagocytosis.

RESULTS
OAβ42 is an innate peptide and a favorable prognostic biomarker of glioma with a prolonged OS in LGG than HGG (P=0.04). Injection of OAβ42 could inhibit the growth of glioma (P=0.0003) through enhancing microglial phagocytosis in the allogeneic mouse model. And the overall survival of the OAβ42 treated mice was longer than the vehicle group (P=.037). The OAβ42 primed microglia phagocytized more glioma cells than vehicle control in a co-culture system (P=0.0007). Autocrine of insulin-like growth factor 1(IGF-1) from OAβ42 activated microglia is essential for engulfing tumor cells.

CONCLUSIONS
Our findings proved OAβ42 modulated microglia could serve as a cellular target for treatment of glioma. Furthermore, our study provides a novel conceptual therapeutic strategy through modulating the function of existing immune cells in the microenvironment.
TMIC-40. BIOPHYSICAL ANALYSIS OF GLIOBLASTOMA CORE AND RIM REVEAL UNIQUE MECHANICAL AND ULTRASTRUCTURAL SIGNATURES
Authors: Mahaffey Bradley , Fowler Zachary , Lung Zoe , Dang Vivien , Frieboes Hermann , Williams Brian , Chen Joseph 
Published: November 2023

Abstract
Glioblastoma (GBM) is a highly aggressive and invasive brain cancer, carrying a median survival of 15 months. This poor prognosis is due, in part, to its resistance to therapy through tumor adaptations mediated by the tumor microenvironment (TME). Efforts to describe the tumor-protective cues in the TME may aid in the development of strategies to combat resistance. Emerging work has indicated that GBM biophysical properties are significant modulators of tumor progression; however, these parameters are poorly described. Here, we investigate the mechanical, extracellular matrix (ECM), and ultrastructural characteristics of tumors in patient matched GBM core and rim tissue. Using atomic force microscopy, immunohistochemistry, and scanning electron microscopy techniques, we find that GBM core is abnormally stiff and dense with large amounts of ECM, while the rim is softer and more porous. The GBM core is uniquely rich in hyaluronic acid and Tenascin-C, ECM proteins known to correlate with tumor stiffness and tumor supportive function. Additionally, dense matrix along with increased levels of hyaluronic acid and Tenascin-C correlate with decreased progression free survival. These data suggest that the stiff core provides increased pro-malignant mechanotransductive cues while the rim presents more permissive routes for GBM invasion. These results reveal a biophysical basis for tumor progression and provides a novel framework for diagnostic strategies and therapeutic intervention.
TMIC-41. LATERAL VENTRICLE PROXIMITY OF GLIOBLASTOMA IS ASSOCIATED WITH LOCALIZED MALIGNANCY-PROMOTING MOLECULAR SIGNATURES IN IMAGE-GUIDED BIOPSIES
Authors: Norton Emily , Ramos-Fresnedo Andres , Cherukuri Yesesri , Whaley Lauren , Schiapparelli Paula , Asmann Yan , Chaichana Kaisorn , Quiñones-Hinojosa Alfredo , Guerrero-Cazares Hugo 
Published: November 2023

Abstract
Glioblastoma (GBM) is the most devastating and common form of primary brain cancer in adults. Tumor location plays a significant role in patient prognosis; in particular, GBM tumors contacting the lateral ventricles (LVs) are more aggressive than LV-distal counterparts. This may be due to interaction of tumors with unique features of the LV microenvironment, including the cerebrospinal fluid (CSF) and neural progenitor cells (NPCs) of the subventricular zone. Despite LV contact having a role on tumor malignancy, studies using bulk tumor samples to identify molecular contributors to LV-contacting prognosis have been only moderately successful, in large part due to intratumoral heterogeneity. Here, we leverage intraoperative surgical navigation to collect matched biopsies of adult LV-contacting primary GBM at locations proximal (&lt; 2 cm) and distal ( &gt; 2 cm) from the LV. Matched samples were collected from ten patients with equal sex distribution and an age range of 46 to 81 years. RNA sequencing of biopsies revealed a localized transcriptional signature of gene expression in LV-proximal locations. These genes include those identified to be associated with GBM malignancy and upregulated in primary GBM cells by CSF exposure or co-culture with NPCs, such as SERPINA3, CD44, and CTSB, as well as many newly identified genes. Implicated biological pathways involved in this transcriptional signature involve inflammation, chemotaxis, Notch signaling, angiogenesis, integrin signaling, and more. The top 50 upregulated genes by LV-proximity of GBM were used to cluster patient transcriptomes from the TCGA GBM database and evaluate the contribution to patient outcome. This analysis revealed a cluster with significantly extended overall survival that displayed a general downregulation of LV-proximity genes. Ultimately, these studies provide evidence that regional tumoral analysis is essential in identifying molecular signatures associated with microenvironmental influence, and that LV-contacting GBM has regional gene expression changes in many genes associated with malignancy.
TMIC-43. THE IMPACT OF MICROGLIA MODULATION ON THE IMMUNE TUMOR MICROENVIRONMENT IN SYNGENEIC GLIOBLASTOMA MOUSE MODELS
Authors: Kaymak Deniz , Shekarian Tala , Ritz Marie-Françoise , Ferrari Nicoletta , Kälin Roland , Glass Rainer , Hutter Gregor 
Published: November 2023

Abstract

BACKGROUND
Glioblastoma is exceptionally resistant to immunotherapies for which the immunosuppressive myeloid compartment is held responsible. As influencer and instructor of T-cell-immunity this compartment mainly consists of Monocyte-derived Cells (MdCs) and tissue-resident (TR) macrophages called microglia (MG). Since the response to immunotherapies depends on antigen presenting cells, we investigate this compartment and its individual role in tumor progression by genetically depleting/activating the TR MG.

METHODS
We made use of two MG-specific and tamoxifen inducible knockout mouse models in which 1) we activate MG by excision of the activation-repressing transcription factor Sall1 and 2) deplete MG by deleting Csf1r on MG. To investigate the effect of MG activation/depletion on the immune tumor microenvironment (iTME), immunocompetent mice were engrafted with syngeneic glioma cells and the iTME subsequently characterized by scRNAseq, spectral flow cytometry and immunofluorescence imaging.

RESULTS
Upon Sall1-KO, MG demonstrate a morphologically reactive phenotype. The deletion of Csf1r depletes the brain parenchyma of MG which rapidly gets repopulated by a morphologically distinct microglia-(like) population. Genetic activation of MG leads to a survival benefit in Gl261-engrafted mice compared to Cre- littermates. In contrast, depletion of MG significantly reduces the survival in Gl261 and CT-2A engrafted mice. ScRNAseq confirms the effective depletion of MG and the subsequent emergence of a MG-like cell cluster that transcriptionally remains distinct. The iTME in MG-depleted mice is characterized by a decreased abundance of exhausted and naïve CD8-Tcells and an increased infiltration of MdCs. GSEA demonstrates a dampened inflammatory profile of infiltrating MdCs.

CONCLUSION
The presence of MG orchestrates the development towards a more antitumorigenic iTME by shaping the antitumoral response of incoming myeloid cells and furthermore directly or indirectly influencing T-cell immunity. Understanding this interplay of MG and MdCs and its impact on instruction of antitumoral T-cell immunity could help guiding the development of novel immunotherapeutic strategies.
TMIC-44. THY1 CONFERS PROLIFERATIVE ADVANTAGES AND THERAPY RESISTANCE WITHIN LOCALIZED NICHES OF GLIOMA
Authors: Ravikumar Visweswaran , Shankar Sunita , Ji Sunjong , Hassan Zainab , Haydin Yacoub , Huang Dah-Luen , Fehmi Ziad , Rehemtulla Alnawaz , Rao Arvind , Al-holou Wajd 
Published: November 2023

Abstract
Resistance to therapy is a hallmark of Glioblastoma (GBM), making it a deadly disease. Earlier, using a longitudinal mouse model, we reported that the immunoglobulin-like cell surface receptor THY1, was significantly upregulated in recurrent GBM tumors. Here, we used single cell and spatial transcriptomics data to track THY1 expression through treatment resistance. Single cell analysis of primary and recurrent GBM shows that THY1 expression is significantly associated with multiple tumor cell states, namely, the NPC-like (Neuronal precursor-like), OPC-like (oligodendrocyte precursor-like) and MES-like (mesenchymal-like) cellular states. Further, spatial analysis of primary GBM shows that tumor cells resident in highly vascularized regions and at invasive edges express significantly high levels of THY1. Specifically, high THY1 levels at the invasive edge is associated with NPC-like state, known to migrate through white matter tracts in vascular regions. In contrast, THY1 expression is high in MES-like cells within recurrent GBM tumor cells. Single cell analysis of a matched primary and recurrent tissue shows a remarkable increase in THY1 expression upon recurrence coincident with a switch to predominantly MES-like state. Using protein markers that define different cellular states we performed immunofluorescence analyses to track the expression of THY1 across both primary and recurrent tumors. We show evidence of high THY1 protein expression associated with NPC-like cells in different niches within primary tumors. In recurrent GBM tissues, THY1 protein expression is significantly higher and present along the palisading regions surrounding necrosis. Finally, we show that dox inducible knockout of THY1 completely abrogates the ability of a patient derived organoid to establish tumors in mice. We are currently exploring this model to study the role of THY1 in therapy resistance. Together, these data suggest that THY1 is critical for tumor growth and upon therapeutic stress can contribute towards shift in tumor cell identity to generate therapy-resistant clonal populations.
TMIC-47. INHIBITION OF MIR-146A-5P DECREASES PROGRESSION OF MELANOMA BRAIN METASTASIS VIA NOTCH PATHWAY DYSREGULATION IN ASTROCYTES
Authors: Rigg Emma , Wang Jiwei , Xue Zhiwei , Lunavat Taral , Liu Guowei , Hoang Tuyen , Parajuli Himalaya , Han Mingzhi , Bjerkvig Rolf , Nazarov Petr , Nicot Nathalie , Kreis Stephanie , Margue Christiane , Nomigni Miléne Tetsi , Utikal Jochen , Miletic Hrvoje , Ystaas Lars , Sundstrøm Terje , Li Xingang , Thorsen Frits 
Published: November 2023

Abstract
Melanoma has a high propensity for brain metastasis, occurring in 40% of late-stage patients. The progression of secondary tumors in the brain depends on the support of the surrounding microenvironment, emphasizing the importance of modulating neighboring cells for successful metastasis. Tumor-derived extracellular vesicles (EVs) play a crucial role in creating a pre-metastatic niche for tumor growth by transferring proteins, RNA, and DNA. This study aims to explore the involvement of melanoma brain metastasis (MBM)-derived EVs in MBM development and identify a target miRNA for potential therapeutic intervention. In an in vivo metastatic model, MBM-EV pre-treated mice exhibited significantly increased MBM tumor burden compared to non-primed mice. In vitro co-cultures of MBM-derived EVs with astrocytes led to astrocyte activation characterized by enhanced proliferation, invasion, cytokine production, and upregulation of GFAP. Microarray analysis revealed significant upregulation of miR-146a-5p in MBM-EVs compared to healthy astrocyte and melanocyte EVs. In situ hybridization of clinical MBM samples showed significantly elevated miR-146a-5p expression compared to healthy brain controls. Sequencing of NHA after co-culture with miR-146a-5p mimic revealed NUMB, a Notch signaling pathway inhibitor, as a miR-146a-5p target. Expression levels of Numb and other downstream Notch proteins were significantly altered in NHA in the presence of MBM-derived EVs and miR-146a. Deserpidine was identified as a potential inhibitor of miR-146a-5p through a drug docking study, and qPCR analysis confirmed reduced miR-146a-5p expression in deserpidine-treated MBM cells and EVs in vitro. In an MBM in vivo model, deserpidine-treated mice exhibited significantly increased survival, reduced tumor burden, and decreased astrocyte activation in both tumor and non-tumor brain tissues. In conclusion, EVs are important regulators of MBM and establish tumor-supporting reactive astrocytes by delivery of miR-146a. Elevated miR-146a levels in patients suggests a potential clinical intervention, and our results indicate deserpidine as a promising candidate for adjuvant therapy.
TMIC-48. SYNAPTIC PROTEINS BASSOON, DLG4, DLG1, MAGI2, SHANK1, AND HOMER1 IN GLIOMA
Authors: Timmer Marco , Lauer Nina , Kuhl Saskia , Goldbrunner Roland 
Published: November 2023

Abstract
To thrive, glioma cells exploit pathways that are active in normal CNS cells, as well as in normal neurotransmitter signaling. In healthy excitatory synapses the postsynaptic submembrane space consists of multiprotein complexes called the postsynaptic density (PSD). The PSD is responsible for the structural organization, the functioning, and the regulation of neuronal signaling. The five MAGUK Proteins DLG4, DLG1, Magi2, Shank1, and Homer1 are part of the healthy PSD complex and play a crucial role not only in NMDA and AMPA receptor signaling. Investigating the role of these MAGUK proteins in glioma biology could bring further insight into which principal neurobiological features, including organization in communicating networks, are recapitulated by tumor cells of different stages in gliomas. qPCR was used to determine expression levels of DLG4, DLG1, Magi2, Shank1, and Homer1 in 7 different glioma groups (GII, GIII, primary GBM before and after chemotherapy, secondary glioblastoma recurrence with and without chemotherapy). Western Blot was done for DLG4, DLG1, and Homer1. Immunohistochemical staining of frozen sections, paraffin sections and in vitro cells was performed. The expression levels of DLG4, DLG1, Magi2, Shank1, and Homer1 were reduced especially in high grade glioma compared to control tissue. A tendency of decreasing protein levels with increasing malignancy is visible for the majority of proteins. In cell culture all proteins were also present. siRNA experiments are ongoing. The presence of these synaptic proteins in glioma tissue and moreover also primary cell culture could indicate a role in tumor biology and the connection of glioma cells with neuronal tissue.