bluuebunny/crossref_metadata_2025_split huggingface dataset:
TMIC-76. PRMT5 MODULATES T CELL PROLIFERATION IN GLIOBLASTOMA TUMOR MICROENVIRONMENT
Authors: Walker Erin , Dowling Aimee , Jung Miyeon , Ertekin Celine , Brown Desmond , Banasavadi-Siddegowda Yeshavanth 
Published: November 2024

Abstract

INTRODUCTION
Glioblastoma, the most common malignant brain tumor, presents a significant obstacle because of its immunosuppressive tumor microenvironment, complicating standard treatment approaches. Protein Arginine Methyltransferase 5 (PRMT5) that regulates cellular functions by symmetrically dimethylating arginine residues is dysregulated in glioblastoma. Inhibiting PRMT5 induces apoptosis and senescence in the differentiated and undifferentiated glioblastoma tumor cells respectively. As PRMT5 is known to play an important role in immune cell response and T cell reprogramming, in this study we sought to probe the role of PRMT5 in the modulation of glioblastoma tumor immune response.

METHODS
We inhibited PRMT5 using small molecule inhibitor (LLY283) or PRMT5 target specific siRNA in patient-derived primary GBM neurospheres (GBMNS) and assessed the T-cell proliferation and MDSC induction by flow cytometry. Further, we also probed for PDL-1 and IL-6 expression by ELISA and westernblot assays. RESULT: PRMT5 inhibition significantly increased CD4+ T-cell proliferation but the MDSC induction was suppressed. As PDL-1/IL-6 axis is known to play a significant role in both anti-tumorigenic T-cell proliferation and pro-tumorigenic MDSC induction, we probed for the expression of PDL-1 and IL-6. While PRMT5 blockade reduced PDL-1 expression, IL-6 expression was upregulated.

CONCLUSION
Our results suggests that PRMT5 inhibition increases T-cell proliferation potentially by blocking MDSC induction. Further studies are underway to understand the nexus between PDL-1/IL-6 and modulation of MDSC/T-cell activation in the context of PRMT5 status in glioblastoma and their potential impact on the anti-tumorigenic effect in an in vivo GBM model.
TMIC-77. ELUCIDATING THE ROLE OF PTPRZ1 SIGNALING IN DRIVING GLIOBLASTOMA PROGRESSION USING THE NOVEL HUMAN ORGANOID TUMOR TRANSPLANTATION SYSTEM
Authors: Kan Ryan , Ge Weihong , Yilgor Can , Fazzari Elisa , Nano Patricia , Azizad Daria , Li Matthew , Ito Joyce , Tse Christopher , Tum Hong , Scholes Jessica , Patel Kunal , Nathanson David , Bhaduri Aparna 
Published: November 2024

Abstract
Glioblastoma (GBM), the most malignant and aggressive primary brain tumor, is driven by both intrinsic genetic mutations and extrinsic factors from the tumor microenvironment (TME). GBM manipulates the TME to enhance its survival and proliferation through mechanisms such as forming functional synapses with adjacent normal cells and secreting immunosuppressive factors. Our laboratory has developed a novel human organoid tumor transplantation (HOTT) model, which allows for the interrogation of tumor-normal cell crosstalk at a molecular level and facilitates the dissection of specific signaling pathways that drive tumor progression and maintenance. Using single-cell transcriptomics on human GBM HOTTs, we identified the PTN-PTPRZ1 ligand-receptor interaction as a critical mediator of tumor-microenvironment communication. PTPRZ1, a receptor tyrosine phosphatase, has been previously implicated in glioma cell migration, and our data further elucidate its role in modulating tumor behavior. Specifically, we demonstrated that knockdown of PTPRZ1 within the TME of human cortical organoids significantly enhances glioma cell migration and inhibits differentiation, underscoring the essential role of PTPRZ1 in maintaining the tumor’s invasive phenotype. Further pharmacological inhibition of PTPRZ1’s catalytic activity with a small molecule revealed that these effects on cell fate determination are independent of its phosphatase activity. This suggests that PTPRZ1 exerts critical non-catalytic functions that are pivotal for GBM progression. To further investigate these non-catalytic mechanisms, we propose utilizing single-cell transcriptomics coupled with proximity labeling and proteomics. This approach will allow us to comprehensively map PTPRZ1-mediated signaling networks and elucidate their impact on tumor biology, potentially unveiling novel therapeutic targets. Our findings revealed a novel axis of GBM biology mediated by PTPRZ1 and highlighted the importance of considering microenvironmental interactions in the development of effective therapeutics for GBM.
TMIC-78. CHEMOTHERAPY INDUCED IMMUNOGENIC RESPONSE IN GLIOMA AND IMPLICATIONS FOR THERAPEUTIC STRATEGIES
Authors: Teasley Damian , Dadario Nicholas , Lei Liang , Sperring Colin , Khoury Nadine , Rolfe Nathaniel , Kristt Melanie , Mela Angeliki , Ifedoria Nkechime , Kotidis Corina , Zhao Wenting , Furnari Julia , Mahajan Aayushi , Pereira Brianna , Argenziano Michael , Winans Nathan , Yoh Nina , Humala Nelson , Dovas Athanassios , Karan Charles , Gill Brian , Sims Peter , Bruce Jeffrey , Canoll Peter 
Published: November 2024

Abstract

INTRODUCTION
Many glioblastoma (GBM) treatments fail because they treat tumor cells in isolation and ignore the surrounding microenvironment. In our phase 1b clinical trial of delivery of Topotecan (TPT) via Convection Enhanced Delivery (CED) in glioma, we demonstrated effective tumor cell elimination accompanied by a robust inflammatory response. We hypothesized that TPT induces an immunogenic response resulting in an unfavorable inflammatory landscape.

METHODS
To characterize chemotherapy’s effect on myeloid cells, we analyzed pre- and post-treatment biopsies from our trial using bulk RNA sequencing to measure canonical myeloid markers. We validated survival benefit of CED in vivo in our tumor model and characterized post-treatment tissue using single cell RNA sequencing (scRNA seq) after 7 days of treatment. We treated slice cultures generated from surgical samples of GBM with TPT and performed scRNA seq and histologic analysis to assess microenvironment changes after 24 hours of treatment. We used several in vitro assays to characterize the direct and indirect mechanisms of myeloid activation.

RESULTS
Bulk RNA sequencing of post treatment biopsies demonstrates upregulation of markers associated with activated and exhausted immune cell populations such as IBA1, CD68, MSR1, MARCO and loss of markers associated with homeostatic microglia such as P2RY12 and TMEM119. Similar results are found within 7 days of treatment in vivo, however, are not found in human derived samples treated acutely. Treatment of in vitro mono and co-culture systems demonstrate a tumor cell death dependent activation of myeloid cell populations via immunogenic molecules.

CONCLUSIONS
Chemotherapies eliminate proliferating glioma cells but also induce inflammation. While many investigators have tried to leverage this activation, our results suggest that chronic inflammation contributes to poor prognosis and recurrence. The identification of molecules responsible for this activation point to new therapeutic targets aimed at controlling treatment-induced inflammation, as part of a combinatorial approach to treat GBM.
TMIC-80. HIGH-DIMENSIONAL HISTOPATHOLOGIC EVALUATION OF THE HYPOXIC TUMOR MICROENVIRONMENT IN GLIOBLASTOMA
Authors: Gandhi Shreya , Singh Olivia , Mansouri Sheila , Karimi Shirin , Lombard Phoebe , Dvorkin-Gheva Anna , Velasquez Carlos , Ali Hafsah , Devaraja Kaviya , Wei Qingxia , Wu Ronald , Li Mira , Cheung May , Voisin Mathew , Gao Andrew , Hedley David , Aldape Kenneth , Wouters Bradley , Zadeh Gelareh 
Published: November 2024

Abstract
Gliobastoma (GBM) is a highly aggressive solid tumor of the brain, characterized by a hypoxic tumor microevironment (TME) leading to histopathological features of necrosis, microvascular proliferation and deregulated hypervascularization. The heterogeneous nature of GBM results in a gradient of intra-tumoral hypoxia that causes molecular changes to specific cell populations within the bulk of the tumor. Our study is the first clinical study to utilize the exogenous oxygen-independent marker pimonidazole (PIMO) to identify the hypoxic TME using high-dimensional spatial and single-cell proteomics of specific cell populations within GBM. A cohort of 35 patients with primary GBM, recurrent GBM or IDH-mutant glioma were administered PIMO prior to surgical resection of tumor tissue for downstream bulk proteomic analysis of bulk tissue by serial immunohistochemistry and imaging mass cytometry (IMC) and single-cell analysis of dissociated tissue by Cytometry by time-of-flight (CyTOF). We utilized high-resolution imaging analyses to validate PIMO as a sensitive and stable marker for hypoxia against a panel of transiently expressed HIF-target genes and examine the inter- and intra-tumoral heterogeneity of hypoxia within each tumor subtype. A custom CyTOF marker panel was developed for further single-cell analyses of T-cell subsets and their functional states, myeloid cell subpopulations, natural killer cells, glial cells, and tumor cells in the hypoxic TME. We demonstrate the utility of PIMO to effectively study the hypoxic TME through spatial and single cell methods and further elucidate mechanisms of hypoxia-driven treatment resistance.
TMIC-86. THE ROLE AND THERAPEUTIC RESEARCH OF NETS IN PROMOTING TMZ RESISTANCE IN GLIOBLASTOMA
Authors: Zhao Shiguang 
Published: November 2024

Abstract

OBJECTIVE
This study aims to investigate the issue of resistance to temozolomide (TMZ) treatment in high-grade glioblastoma (GBM), specifically the association between TMZ resistance, the tumor microenvironment (TME), and neutrophil activity. The research hypothesis posits that changes in neutrophils induced by TMZ treatment, particularly the formation of neutrophil extracellular traps (NETs), may lead to TMZ resistance in GBM cells.

METHODS
The study utilized clinical data analysis and animal model research to evaluate changes in neutrophils during TMZ treatment and their impact on treatment efficacy. Proteomics analysis and high-throughput sequencing were employed to investigate the effect of TMZ on cytokine secretion by GBM cells and how these cytokines stimulate the release of NETs. Additionally, gene ontology (GO) analysis and bioinformatics methods were used to study how NETs promote the epithelial-mesenchymal transition (EMT) process and TMZ resistance by activating specific signaling pathways such as Jak-Stat3.

RESULTS
The study found that TMZ treatment led to increased neutrophil infiltration, which was associated with poor prognosis in GBM patients. TMZ treatment altered the levels of cytokines secreted by GBM cells, particularly IL-6, promoting the release of NETs by neutrophils. The formation of NETs was closely related to the activation of Stat3 signaling and the promotion of the EMT process in tumor cells, thereby enhancing TMZ resistance. Magnesium-based micromotors were found to improve TMZ efficacy by scavenging ROS production in neutrophils, inhibiting the release of NETs.

CONCLUSION
This study confirms the association between TMZ resistance and neutrophil activity, particularly the role of NETs in promoting EMT and resistance. These findings provide new insights into the treatment of GBM and offer a theoretical basis for the development of therapeutic strategies targeting NETs, which may improve the response of glioblastoma to TMZ treatment by inhibiting ROS production. The development of this novel therapeutic approach offers new treatment options for postoperative chemotherapy in GBM.
TMIC-87. ICAM-1 REGULATE EXTRACELLULAR VESICLE-MEDIATED IMMUNOSUPPRESSIVE MONOCYTE IN HUMAN GLIOBLASTOMA CELL
Authors: Jung Mi-Yeon , Oishi Masahiro , Walker Erin N , Barnes David , Nusraty Sabrina , Siddegowda Yesh Banasavadi , Parney Ian F , Brown Desmond A 
Published: November 2024

Abstract
Glioblastoma is the most common malignant primary brain tumor and is universally fatal. Treatment involves maximal safe resection with adjuvant chemoradiation. Poor prognosis in glioblastoma is multifactorial, and local and systemic immunosuppression is an important factor. Extracellular vesicles (EVs) are small, membrane-bound particles released by cells into the external environment. They play a key role in intercellular communication. In glioblastomas, EVs regulate immunosuppression through induction of myeloid-derived suppressor cells (MDSCs) in a process dependent on the PD-1/PD-L1 and IL-6 axes. Primary cilia are microtubule-based organelles that play crucial roles in various cellular processes and signal transduction cascades. We recently showed that primary cilia modulate IL-6 expression and consequently, MDSC induction. Comparative proteomic analysis of EVs derived from human glioblastoma cells devoid of cilia showed loss of ICAM-1 expression compared to control glioblastoma cells. ICAM-1 (Intercellular Adhesion Molecule-1) is a cell surface glycoprotein that mediates cell-cell adhesion and immune responses. In this study, we showed that depletion of primary cilia in human glioblastoma cells result in increased PD-L1 but loss of IL-6 and ICAM-1. RNAi-meidated loss of ICAM-1 was synergistic with primary cilia depletion in preventing MDSC inductionn normal human monocytes exposed to glioblastoma-derived EVs. Exogenous IFN-g was sufficient to restore IL-6 levels and MDSC induction despite loss of primary cilia and ICAM-1 suggesting that primary cilia act upstream of IFN-g, IL-6 and ICAM-1 in glioblastoma-mediated MDSC induction. This study is the first to connect primary cilia signal transduction to IL-6 and ICAM-1 expression and to MDSC induction. The evidence suggests a potential parallel primary cilia regulatory cascade independent of the PD-L1 axis that controls tumor-mediated immunosuppression. These results may inform novel therapeutic strategies aimed at increasing efficacy of immunotherapy in the glioblastoma and other neoplastic processes.
TMOD-12. DEFINING THE ROLE OF THE DAAM2 R414W GERMLINE VARIANT IN FAMILIAL GLIOMA
Authors: Choy Tiffany , Ye Qi , Deneen Benjamin , Bondy Melissa , Lee Hyun Kyoung 
Published: November 2024

Abstract
Malignant glioma is the most common primary brain tumor in adults, leading to high morbidity and mortality due to its aggressive nature and limited efficacious treatment options. To improve this prognosis, research has focused on genetic factors that may contribute to glioma. While most glioma cases arise from sporadic somatic mutations, approximately 5-10% are classified as familial glioma, stemming from inherited genetic variations. Although several studies have explored mechanisms behind somatic mutations in glioma, less is known about hereditary variants that promote glioma susceptibility. We recently discovered five germline mutations in Daam2 (Dishevelled associated activator of morphogenesis 2) from familial glioma patients. To examine the role of these mutations in familial glioma, we overexpressed these mutations in patient-derived glioma stem-like cells, which were subsequently orthotopically xenografted into immunodeficient mice. We identified that one of these mutations, Daam2-R414W, promotes tumor cell proliferation both in vitro and in vivo. To further understand the role of the Daam2-R414W mutation in familial glioma, we generated a knock-in immunocompetent mouse model with the Daam2-R414W mutation. In these mutant mice, we found an increased number of proliferating glial progenitor cells in the subventricular zone compared to Daam2 wildtype mice, suggesting the potential of the Daam2-R414W mutation to influence glial progenitor expansion to stimulate glioma initiation. Furthermore, to establish a potential mechanism, we performed proteomic profiling of Daam2 wildtype and Daam2-R414W overexpression tumors and found enrichment of Git1, a GTPase-activating protein involved in cytoskeletal remodeling, suggesting that the Daam2-R414W variant may interact with Git1 to promote tumor invasion. Our findings thus far identify a hereditary genetic variant with the potential to increase the risk of glioma, shedding light on the repercussions of a human developmental gene variant and its potential to disrupt normal cellular machinery to promote malignancy and glioma development.
TMOD-19. GERMLINEELP1 DEFICIENCY SENSITIZES CEREBELLAR GRANULE NEURON PROGENITORS TO SHH MEDULLOBLASTOMA
Authors: Tanveer Ahmad Shiekh , Garcia-Lopez Jesus , Li Yiran , Hadley Jennifer , Paul Leena , Gudenas Brian , Batts Melissa , Soliman Taha , Pitre Aaron , Kojic Marija , Manz Frederik , Zindy Frederique , Jones Alun , Mayasundari Anand , Bianski Brandon , Tinkle Christopher , Shirinifard Abbas , Janke Laura Janke , Lu Meifen , Onar-Thomas Arzu , Pfister Stefan , Gajjar Amar , Baker Suzanne , Roussel Martine , Rankovic Zoran , Robinson Giles , Orr Brent , Wainwright Brandon , Kutscher Lena , Waszak Sebastian , Lin Hong , Northcott Paul 
Published: November 2024

Abstract
Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events observed in medulloblastoma (MB), accounting for 30% of the Sonic Hedgehog 3 subtype (SHH-3). Molecularly, ELP1-associated SHH-MBs acquire somatic PTCH1 mutations in &gt;80% of cases, and universal loss-of-heterozygosity of the wild-type ELP1 and PTCH1 alleles through loss of chromosome-arm 9q, resulting in their biallelic inactivation. Notably, germline ELP1 LOF occurs mutually exclusive with somatic/germline TP53 mutations in the SHH-3 subtype, suggesting that genetic perturbation of either ELP1 or TP53 may promote similar downstream oncogenic consequences in cerebellar granule neuron progenitors (GNPs), the accepted cellular origin of SHH-MB. Despite these findings, the molecular, biochemical, and cellular mechanism(s) by which ELP1-deficiency provokes malignant pathogenesis remain unknown. In this study, we sought to close this knowledge gap and functionally determine why children harboring pathogenic ELP1 germline variants are at an increased risk of developing SHH-MB. Mice were genetically engineered to mimic heterozygous Elp1 LOF (Elp1HET). We studied the effect of loss of ELP1 in GNPs using a combination of molecular profiling, immunophenotyping, and cellular assays. GNPs from Elp1HET exhibited a spectrum of molecular and biochemical hallmarks of malignant transformation including increased DNA replication stress, DNA damage, accelerated cell cycle progression, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs engineered to harbor somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the specificity of ELP1-associated tumors in SHH-3, and their exclusivity with TP53-mutant tumors. Treatment of ELP1-mutant patient-derived xenografts with an FDA-approved MDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Collectively, our findings functionally substantiate the role of ELP1 deficiency in predisposition to SHH-3 MB and nominate therapeutic strategies to overcome p53 inhibition as a rational treatment option.
TMOD-20. RAPID PROCESSING AND BIOBANKING OF RESECTED BRAIN TUMOR TISSUE TO GENERATE PATIENT-DERIVED BRAIN TUMOR EXPLANT ORGANOIDS (GBOS) FOR PRECLINICAL STUDIES
Authors: Palethorpe Helen , Shard Chloe , Ryan Conor , Wenholz Daniel , Truong Quach , Scheer Kaitlin , Skarne Niclas , Patil Ashwini , Ormsby Rebecca , Poonnoose Santosh , Alexander Kimberley , Gan Hui , Day Bryan , Kumar Naresh , Wilkinson John , Gomez Guillermo 
Published: November 2024

Abstract
Improved preclinical tools are urgently needed to translate new brain cancer treatments. Patient-derived brain tumor explant organoids (GBOs) offer promise for studying tumor cells in a relevant human tumor microenvironment and predicting patient responses to therapy. However, generating GBOs is time-consuming, costly, and technically challenging, hindering the creation of comprehensive biobanks covering the spectrum of brain tumor heterogeneity. This work presents a semi-automated method for producing GBOs, involving tumor tissue processing, size selection, and same-day cryopreservation, reducing generation time to less than 1 hour. We established a biobank of 24 GBOs from 33 samples (11 males and 13 females) with primary (n=13, GBO Yield (GY)&gt;90%) and recurrent (n=5, GY&gt;90%) glioblastomas, high-grade gliomas (HGG, n=2, GY≤50%), and low-grade gliomas (LGG, n=2 with GY&gt;90%, n=2 with GY≤50%). Using GBO size and propidium iodide as readouts, we used this biobank to compare anticancer activities of novel idronoxil-conjugated benzopyran compounds (NX786, NX904/904E1) against Bortezomib (100% cell death reference). NX786 and NX904/904E1 reduced GBO growth (≥50%) in all primary glioblastoma and one (of two) recurrent glioblastoma GBOs with milder effects in LGG GBOs. Two (of four) primary glioblastoma, one (of two) recurrent glioblastoma, and one LGG GBOs exhibited significant cell death (&gt;60%) in response to NX904/904E1. In contrast, NX786 induced cell death in one (of three) primary glioblastoma (34% cell death) and one (of two) recurrent glioblastoma (71% cell death) GBOs but not in LGG GBOs, together showcasing varied responses across different brain tumors. Highly-passaged GBOs lacking the non-malignant tumor microenvironment were more susceptible to these treatments, underlining the tumor microenvironment’s critical role in responses to anticancer agents. We provide a new method for efficient processing and cryopreserving GBOs, enabling the establishment of large biobanks for patient-specific preclinical drug testing across brain tumor subgroups in a clinically relevant human 3D model.
TMOD-21. MOUSE MODEL TO CONDITIONALLY EXPRESS A DIFFUSE MIDLINE GLIOMA DERIVED MUTATION IN THE ONCOGENIC PHOSPHATASE PPM1D
Authors: Valentine Vennesa , Liu Harrison , Groth Abby , Maingi Spencer , Saravanapavan Avneesh , Tolliver Joshua , Williams Nerissa , Luo Lixia , Kirsch David , Reitman Zachary 
Published: November 2024

Abstract
Diffuse Midline Gliomas (DMGs) are incurable brain tumors of children and adults, and there is an urgent need for new therapeutic approaches. Their location within critical areas of the brain precludes complete surgical removal. While current treatment mainly relies on radiation therapy, its efficacy remains palliative. DMGs commonly harbor truncating mutations in the Mn2+/Mg2+-dependent protein phosphatase 1D (PPM1D), leading to a gain-of-function in PPM1D by enhancing protein stability and activity. Thus, investigating PPM1D protein expression and its regulatory mechanisms is crucial for understanding its oncogenic role and identifying therapeutic targets. To address this, we developed a Ppm1d-loxP-exon6-loxP-exon6-E518X-tag mouse allele (Ppm1d-FL). This allele allows conditional expression of DMG-derived truncating mutations from the endogenous Ppm1d locus when the loxP sites are recombined in the presence of Cre recombinase. Tosimulate primary gliomas, we utilized the RCAS/tv-a retrovirus system and Cre/loxP recombination platforms. Mouse pups were injected with RCAS retroviruses bearing oncogenic platelet-derived growth factor B, Cre recombinase, and luciferase reporter genes into the brainstem. We confirmed that Cre leads to expected recombination of Ppm1d-FL, leading to expression of DMG-derived truncated Ppm1d-E518X-Tag mRNA. We examined tumor-free survival data, which indicates accelerated tumor formation with Ppm1d-FL compared to littermate controls with wildtype Ppm1d. The tumors demonstrated expression of molecular biomarkers commonly found in DMGs. Single-cell RNA sequencing has identified pathways activated or inactivated upon Ppm1d mutation. These data shed light on the complex interplay between PPM1D mutations and glioma pathogenesis and may guide the design of therapies that target PPM1D molecular pathways.