bluuebunny/crossref_metadata_2025_split huggingface dataset:
TAMI-57. INDUCTION OF FERROPTOSIS PROMOTES IMMUNOGENIC CELL DEATH AND ACTIVATION OF THE IMMUNE MICROENVIRONMENT IN GLIOMA
Authors: Argenziano Michael , Banu Matei , Dovas Athanassios , Zhao Wenting , Furnari Julia , Higgins Dominique , Upadhyayula Pavan , Mahajan Aayushi , Humala Nelson , Sims Peter , Bruce Jeffrey N , Canoll Peter 
Published: November 2021

Abstract
Gliomas are immune cold tumors. Effective therapeutic strategies capable of inducing an immune response are lacking.Here we present evidence that ferroptosis, a form of iron-mediated lipid peroxidation-based cell death, may promote anti-tumor immunity via stimulation of phagocytosis and pro-inflammatory activities in microglia. While ferroptosis has shown promise in induction of glioma cell death, the immunogenic and microenvironmental effects of glioma ferroptosis are poorly understood. First, we tested the in vitro effects of the glutathione peroxidase 4 (GPX4) inhibitor RSL3, a ferroptosis inducer, on murine glioma cell lines. Using flow cytometry, we discovered that RSL3 treatment led to membrane translocation of the pro-phagocytic antigen calreticulin, known hallmark of immunogenic cell death, by an average log2-fold-change of 2.53 (p= 0.03) compared to DMSO-treated controls. This effect correlated with lipid peroxidation, as assessed by BODIPY-C11 staining. To further test the effects of ferroptosis on glioma cell-microglia crosstalk, we prepared acute brain tumor slices from both mouse and human glioma samples, and treated them with RSL3. Quantification of immunofluorescent staining from three independent human slice cultures after RSL3 treatment demonstrated a significant increase in calreticulin abundance as compared to control (p &lt; 0.001). Importantly, this effect was significantly diminished with addition of ferrostatin, an inhibitor of ferroptosis, demonstrating that ferroptosis induction was directly responsible for calreticulin translocation. Single-cell RNAseq on mouse and human acute glioma slice cultures treated with RSL3 demonstrated significant overexpression of calreticulin in the tumor population, and positive enrichment of interferon signaling, antigen presentation, and phagocytosis ontologies in both tumor and myeloid compartments. These findings suggest that ferroptosis-induced translocation of calreticulin on the surface of glioma cells promotes activation of the local immune microenvironment by increasing tumor antigen presentation and pro-inflammatory cytokine release by tumor-associated microglia. Thus, ferroptosis-inducing drugs may promote anti-tumor immunity through the activation of immunogenic cell death signals.
TAMI-63. INHIBITION OF LINEAGE STATES WITHIN GBM OVERCOMES CHEMO-RESISTANCE
Authors: Joseph Kevin , Maier Julian , Ravi Vidyha , Beck Jürgen , Hofmann Ulrich , Heiland Dieter Henrik , Schnell Oliver 
Published: November 2021

Abstract

OBJECTIVE
Novel insights into the developmental trajectory exhibited by glioblastoma (GBM) have shown that it has the capability to respond to its microenvironment by clonal selection of specific transcriptional phenotypes. Using the same mechanisms, malignant GBM develop intrinsic mechanisms to resist chemotherapeutic treatments. In this study, we determine the role of the metabotropic glutamate receptor 3 (mGluR3) in chemoresistance and show that inhibition of mGluR3 leads to significant loss of tumor growth volume when concomitantly treated with Temozolomide.

METHODS
Transcriptomic analysis was carried out post mGlur3 receptor inhibition using LY341495 (100nM), to study loss of transcriptional programs. Morphological and cellular kinetic analysis was carried out post inhibition, to determine apoptosis/necrosis rate, when combined with Temozolomide. The efficacy of the treatment within a human like environment was assessed using our novel human cortical GBM model.

RESULTS
We present transcriptional and morphological evidence that mGluR3 inhibition using LY341495 leads to loss of both lineage (FDR&lt; 0.01) and reactive (FDR&lt; 0.01) transcription programs. This leads to a loss of ability to evade cytotoxicity when combined with Temozolomide treatment, validated using kinetic apoptosis (p&lt; 0.01). When our cortical GBM model was used to study the effect of treatment within the appropriate microenvironment, we see that the combination therapy leads to a significant reduction in tumor growth (p&lt; 0.01) over the course of 10 days.

CONCLUSION
Through the integration of diversified molecular-biological analyses, we illustrate a new picture of how glutamate signaling via mGluR3 interacts with phenotypical GBM transcriptional programs to evade effective therapy, the inhibition of which leads to loss of chemo-resistance.
TAMI-67. INVESTIGATION OF THE COMPLEMENT SYSTEM IN THE IRRADIATED BRAIN TUMOR MICROENVIRONMENT
Authors: Rosberg Rebecca , Smolag Karolina , Pantazopoulou Vasiliki , Blom Anna , Pietras Alexander 
Published: November 2021

Abstract
Glioblastoma is the most common and aggressive primary brain tumor in adults. Despite treatment through surgery, irradiation and chemotherapy all patients suffer recurrence of treatment-resistant tumors and the survival prognosis remains poor. The recurrence of tumors is driven by the invasive nature of the tumor and appears to be related to cells with stem like characteristics that are present in perivascular and hypoxic niches. Previous studies from our lab showed that astrocytes grown in hypoxic or irradiated conditions increase the stemness of glioma cells. The altered behavior of the astrocytes leads to increased cell size and a change in secreted cytokines. Reactive astrocytes are important in other central nervous system (CNS) diseases involved in tissue repair such as traumatic brain injury and Alzheimer’s disease. Interestingly, in several neurological diseases, reactive astrocytes upregulate complement proteins, especially complement component 3 (C3). However, it remains relatively unexplored how these complement proteins in stromal astrocytes are expressed in glioblastoma. Tissue sections from our glioma mouse model shows presence of C3 around hypoxic areas where there is an abundance of astrocytes. We have also shown that astrocytes grown at 21%, 1% and 0.1% oxygen upregulate complement protein C3 as well as other proteins associated with a more extensive infiltrative phenotype of glioblastoma. Datasets with human patients showed that C3 expression was correlated with higher grade tumors and that patients with tumors expressing C3 had more risk to get new tumors after primary treatment (including but not limited to radiotherapy). In this ongoing project, we are investigating whether activation of the complement system in the tumor microenvironment contributes to tumor progression. The upregulation of C3 in astrocytes in hypoxic conditions could therefore through local complement activation possibly led to tumor promoting signaling leading to beneficial survival of therapies of nearby glioma cells.
TAMI-72. DIVERSITY OF CELLULAR COMMUNICATION IN GLIOBLASTOMA
Authors: Joseph Kevin , Vollmer Lea , Ravi Vidyha , Beck Jürgen , Hofmann Ulrich , Schnell Oliver , Heiland Dieter Henrik 
Published: November 2021

Abstract

OBJECTIVE
Owing to recent advances in understanding of the active functional states exhibited within glioblastoma (GBM), intra-tumoral cellular signaling has moved into focus of neuro-oncology. In this study, we aim to explore the diversity of transcellular signaling and investigate correlations between transcriptional dynamics and functional signaling.

METHODS
Electrophysiological characterization of GBM was carried out using planar microelectrodes and Ca2+ imaging, in both 2D cell culture as well as in our novel human cortical GBM model. Exposure to physiologically relevant conditions present within the tumor was carried out to identify specific signaling cells of interest and capture the signaling diversity in response to environmental conditions. Transcriptional dynamics and plasticity were examined by means of scRNA-sequencing with CRISPR based perturbation, spatial transcriptomics and deep long-read RNA-sequencing.

RESULTS
Electrophysiological profiles of multiple primary GBM cell lines revealed characteristics of scale-free networks (R2=0.875), confirmed in both 2D culture as well as a human neocortical GBM model. When GBM was cultured in a “in-vivo” like environment, basal activity was significantly higher (50%, p=0.01). Cellular signaling was directly correlated to changes in the environment, like hypoxia or glutamatergic activation, and total inhibition of electrical signaling required the usage of synaptic inhibitors. Using single-cell RNA sequencing and proteomics, several synaptogenesis related genes were identified to play a crucial role in the lineage states present in GBM. CRISPR based perturbation of these genes resulted in alterations in cellular morphology and decreased cellular connectivity (p&lt; 0.01), with loss of scale free features (R2=0.35), and transcriptomic loss of developmental lineages (FDR&lt; 0.01), leading to significant inhibition of GBM stress response.

CONCLUSION
Our findings highlight the role of electrical signaling in glioblastoma. Cellular stressors induce intercellular signaling, leading to transcriptional adaptation suggesting that there exists a highly complex and powerful mechanism for dynamic transcriptional state adaptation.
TAMI-74. SPATIOTEMPORAL MULTI-OMIC LANDSCAPE OF HUMAN MEDULLOBLASTOMA AT SINGLE CELL RESOLUTION
Authors: Liu Hailong , Qiu Xiaoguang , Jiang Tao 
Published: November 2021

Abstract
Medulloblastoma is the most common malignant childhood tumor type with distinct molecular subgroups. While advances in the comprehensive treatment have been made, the mortality in the high-risk group is still very high, driven by an incomplete understanding of cellular diversity. Here we use single-nucleus RNA expression, chromatin accessibility and spatial transcriptomic profiling to generate an integrative multi-omic map in 40 human medulloblastomas spanning all molecular subgroups and human postnatal cerebella, which is supplemented by the bulk whole genome and RNA sequences across 300 cases. This approach provides spatially resolved insights into the medulloblastoma and cerebellum transcriptome and epigenome with identification of distinct cell-type in the tumor microenvironment. Medulloblastoma exhibited three tumor subpopulations including the quiescent, the differentiated, and a stem-like (proliferating) population unique to cancer, which localized to an immunosuppressive-vascular niche. We identified and validated mechanisms of stem-like to differentiated process among the malignant cells that drive tumor progression. Integration of single-cell and spatial data mapped ligand-receptor networks to specific cell types, revealing stem-like malignant cells as a hub for intercellular communication. Multiple features of potential immunosuppression and angiogenesis were observed, including Treg cells and endothelial cells co-localization in compartmentalized tumor stroma. Collectively, our study provides an integrative molecular landscape of human medulloblastoma and represents a reference to advance mechanistic and therapeutic studies of pediatric neuro-oncological disease.
TMOD-01. AN IN VIVO FUNCTIONAL GENOMICS SCREEN TO IDENTIFY NOVEL DRIVERS OF LUNG-TO-BRAIN METASTASIS
Authors: Aghaei Nikoo , Lam Fred C , Kasper Ekkhard , Venugopal Chitra , Singh Sheila K 
Published: November 2021

Abstract

INTRODUCTION
Brain metastases, the most common tumors of the central nervous system, occur in approximately 20% of primary adult cancers. In particular, 40% of patients with non-small cell lung cancer develop brain metastasis. As systemic therapies for the treatment of non-small cell lung cancer become increasingly effective at controlling primary disease, patients are ironically succumbing to their brain metastases. This highlights a large unmet need to develop novel targeted therapies for the treatment of lung-to-brain metastases (LBM). We hypothesize that an in vivo functional genomic screen can identify novel genes that drive LBM.

METHODS
To do this, we developed a patient-derived xenograft (PDX) mouse model of LBM using patient lung cancer cell lines. This PDX model of LBM enables the use of fluorescent and bioluminescent in vivo imaging to track the progression of lung tumor and brain metastases.

RESULTS
We have performed an in vivo genome-wide CRISPR activation screening to identify novel drivers of LBM. We will derive candidate genes through mouse brain and lung tissue sequencing after mice reach endpoint.

EXPECTED AREA OF FINDINGS
This platform will lead to potential therapeutic targets to prevent the formation of LBM and prolong the survival of patients with non-small cell lung cancer.

LIMITATIONS
There may be limitations in getting candidate hits that overlap in all mice in our first replicate. This can be remedied by conducting the in vivo screen in at least three biological replicates.

CONCLUSION
To the best of our knowledge, this is the first genome-wide in vivo CRISPR activation screen searching for drivers of LBM using a PDX animal model. This study can provide a framework to gain a deeper understanding of the regulators of BM formation which will hopefully lead to targeted drug discovery.
TMOD-25. LATENT SOX9-POSITIVE CELLS BEHIND MYC-DRIVEN MEDULLOBLASTOMA RELAPSE
Authors: Borgenvik Anna , Bolin Sara , Savov Vasil , Holmberg Karl O , Zhao Miao , Rosén Gabriela , Hutter Sonja , Garancher Alexandra , Rahmanto Aldwin Suryo , Bergström Tobias , Mainwaring Oliver , Sattanino Damiana , Verbaan Annemieke D , Rusert Jessica , Sundström Anders , Dang Yonglong , Wenz Amelie , Richardson Stacey , Fotaki Grammatiki , Giraud Geraldine , Hill Rebecca , Dubuc Adrian , Kalushkova Antonia , Remke Marc , Cancer Matko , Jernberg-Wiklund Helena , Chen xingqi , Taylor Michael D , Sangfelt Olle , Clifford Steven , Schüller Ulrich , Wechsler-Reya Robert , Weishaupt Holger , Swartling Fredrik 
Published: November 2021

Abstract
Tumor recurrence developing from therapy resistance, immune escape and metastasis is the leading cause of death in medulloblastoma, the most frequent malignant pediatric brain tumor. Amplification of MYC genes is the most common genetic alteration in Group 3 and Group 4 subgroups that constitute two thirds of medulloblastoma. SOX9 is a transcription factor present in stem cells in the normal brain but is limited to rare, quiescent cells in medulloblastoma patients with MYC gene amplifications. By studying paired primary-recurrent patient samples and patient-derived xenografts we here identified significant accumulation of SOX9-positive cells in Group 3 and Group 4 relapses. To follow relapse at the single cell level we developed an inducible dual Tet model of MYC-driven MB, where MYC was re-directed from the treatment-sensitive bulk cells to resistant, dormant SOX9-positive cells by doxycycline. In this model, distant recurrent tumors and spinal metastases developed. SOX9 promoted immune escape, DNA repair suppression and was essential for recurrence. Tumor cell dormancy was non-hierarchical, migratory and depended on MYC suppression by SOX9 to promote relapse. By using computational modeling and treatment we also showed how doxorubicin and MGMT inhibitors were specifically targeting recurrent cells that could be of potential use in future treatments for patients affected by these fatal relapses.
TMOD-31. AN ORGANOTYPIC TISSUE PLATFORM TO BRIDGE IN VITRO AND IN VIVO ASSAYS FOR BRAIN CANCER TREATMENT
Authors: Mann Breanna , Bell Noah , Dunn Denise , Floyd Scott , Hingtgen Shawn , Satterlee Andrew 
Published: November 2021

Abstract
Brain cancers remain one of the greatest medical challenges. The lack of experimentally tractable models that recapitulate brain structure/function represents a major impediment. Platforms that enable functional testing in high-fidelity models are urgently needed to accelerate the identification and translation of therapies to improve outcomes for patients suffering from brain cancer. In vitro assays are often too simple and artificial while in vivo studies can be time-intensive and complicated. Our live, organotypic brain slice platform can be used to seed and grow brain cancer cell lines, allowing us to bridge the existing gap in models. These tumors can rapidly establish within the brain slice microenvironment, and morphologic features of the tumor can be seen within a short period of time. The growth, migration, and treatment dynamics of tumors seen on the slices recapitulate what is observed in vivo yet is missed by in vitro models. Additionally, the brain slice platform allows for the dual seeding of different cell lines to simulate characteristics of heterogeneous tumors. Furthermore, live brain slices with embedded tumor can be generated from tumor-bearing mice. This method allows us to quantify tumor burden more effectively and allows for treatment and retreatment of the slices to understand treatment response and resistance that may occur in vivo. This brain slice platform lays the groundwork for a new clinically relevant preclinical model which provides physiologically relevant answers in a short amount of time leading to an acceleration of therapeutic translation.
CNTM-01. Evaluating Traditional and Non-Traditional Eloquent Areas in Patients with Brain Tumors: Large-scale Network Analysis Using a Machine Learning-Based Platform
Authors: Morell Alexis , Eichberg Daniel , Shah Ashish , Luther Evan , Lu Victor , Komotar Ricardo , Ivan Michael 
Published: November 2021

Abstract

BACKGROUND
Developing mapping tools that allow identification of traditional or non-traditional eloquent areas is necessary to minimize the risk of postoperative neurologic deficits. The objective of our study is to evaluate the use of a novel cloud-based platform that uses machine learning to identify cerebral networks in patients with brain tumors.

METHODS
We retrospectively included all adult patients who underwent surgery for brain tumor resection or thermal ablation at our Institution between the 16th of February and the 15th of May of 2021. Pre and postoperative contrast-enhanced MRI with T1-weighted and high-resolution Diffusion Tensor Imaging (DTI) sequences were uploaded into the Quicktome platform. After processing the data, we categorized the integrity of seven large-scale brain networks: sensorimotor, visual, ventral attention, central executive, default mode, dorsal attention and limbic. Affected networks were correlated with pre and postoperative clinical data, including neurologic deficits.

RESULTS
Thirty-five (35) patients were included in the study. The average age of the sample was 63.2 years, and 51.4% (n=18) were females. The most affected network was the central executive network (40%), followed by the dorsal attention and default mode networks (31.4%), while the least affected were the visual (11%) and ventral attention networks (17%). Patients with preoperative deficits showed a significantly higher number of altered networks before the surgery (p=0.021), compared to patients without deficits. In addition, we found that patients without neurologic deficits had an average of 2.06 large-scale networks affected, with 75% of them not being related to traditional eloquent areas as the sensorimotor, language or visual circuits.

CONCLUSIONS
The Quicktome platform is a practical tool that allows automatic visualization of large-scale brain networks in patients with brain tumors. Although further studies are needed, it may assist in the surgical management of traditional and non-traditional eloquent areas.
ITVT-01. 5-ALA PDT and Targeting MEK/ERK Signaling Elicits Synergistic Antitumor Effects in Diffuse Midline Glioma
Authors: Price Gabrielle , Rivera Daniel , Bouras Alexandros 
Published: November 2021

Abstract
Diffuse midline gliomas are highly invasive, unresectable tumors in children. To date, there is no effective treatment for DMG. Concurrent radiotherapy (RT) and systemic therapies, the standard of care, has only been successful in providing limited disease control. The major obstacle to therapy is the selectively permeable blood brain barrier (BBB) that limits systemic drug delivery. Given the unmet need for penetrant and minimally invasive DMG treatments, photodynamic therapy (PDT), with the precursor photosensitizing agent 5-aminolevulinic acid (5-ALA), is an oncologic treatment that holds promise. 5-ALA PDT of tumors occurs by targeting tumor cells that accumulate the 5-ALA metabolite, protoporphyrin IX (PPIX), with 635 nm light to create deadly reactive oxygen species (ROS). We explore the synergism of 5-ALA PDT with the MEK inhibitor, trametinib, since the RAS/MEK signaling pathway regulates tumor cell proliferation and survival and has been shown to therapeutically enhance PDT in select carcinoma models. We demonstrated that sub-micromolar levels of 5-ALA PDT and nanomolar levels of trametinib successfully decrease cell proliferation and induce apoptosis in DMG cell lines. Cell viability assays revealed that drug response differs based on the histone mutation (H3.1 or H3.3) of the line. Mechanisms of decreased cell survival involves the generation of reactive oxygen species that induces programmed cell death. Through the use of a DMG genetically engineered mouse model, we also found 5-ALA PDT to induce apoptosis in vivo. The synergistic effects of MEK inhibition and 5-ALA PDT in vitro and apoptotic effects of 5-ALA PDT in vivo, highlights the potential therapeutic efficacy of this treatment modality.
ITVT-10. Using functional Ultrasound (fUS) for real-time, depth-resolved functional and vascular delineation of brain tumors with micrometer-millisecond precision
Authors: Soloukey Sadaf , Verhoef Luuk , Mastik Frits , Generowicz Bastian , Bos Eelke , Schouten Joost , Harhangi Biswadjiet , Collée Ellen , Satoer Djaina , Smits Marion , Dirven Clemens , De Zeeuw Chris , Koekkoek Sebastiaan , Vincent Arnaud , Kruizinga Pieter 
Published: November 2021

Abstract

BACKGROUND
Neurosurgical practice still relies heavily on pre-operatively acquired images to guide tumor resections, a practice which comes with inherent pitfalls such as registration inaccuracy due to brain shift, and lack of real-time functional or morphological feedback. Here we describe functional Ultrasound (fUS) as a new high-resolution, depth-resolved, MRI/CT-registered imaging technique able to detect functional regions and vascular morphology during awake and anesthesized tumor resections.

MATERIALS AND METHODS
fUS relies on high-frame-rate (HFR) ultrasound, making the technique sensitive to very small motions caused by vascular dynamics (µDoppler) and allowing measurements of changes in cerebral blood volume (CBV) with micrometer-millisecond precision. This opens up the possibility to 1) detect functional response, as CBV-changes reflect changes in metabolism of activated neurons through neurovascular coupling, and 2) visualize in-vivo vascular morphology of pathological and healthy tissue with high resolution at unprecedented depths. During a range of anesthetized and awake neurosurgical procedures we acquired vascular and functional images of brain and spinal cord using conventional ultrasound probes connected to a research acquisition system. Building on Brainlab’s Intra-Operative Navigation modules, we co-registered our intra-operative Power Doppler Images (PDIs) to patient-registered MRI/CT-data in real-time.

RESULTS
During meningioma and glioma resections, our co-registered PDIs revealed fUS’ ability to visualize the tumor’s feeding vessels and vascular borders in real-time, with a level of detail unprecedented by conventional MRI-sequences. During awake resections, fUS was able to detect distinct, ESM-confirmed functional areas as activated during conventional motor and language tasks. In all cases, images were acquired with micrometer-millisecond (300 µm, 1.5–2.0 ms) precision at imaging depths exceeding 5 cm.

CONCLUSION
fUS is a new real-time, high-resolution and depth-resolved imaging technique, combining favorable imaging specifications with characteristics such as mobility and ease of use which are uniquely beneficial for a potential image-guided neurosurgical tool.