bluuebunny/crossref_metadata_2025_split huggingface dataset:
TAMI-21. MALIGNANT GLIOMAS REMODEL FUNCTIONAL NEURAL CIRCUITS THROUGH PARACRINE SIGNALING WHICH CONFERS A NEGATIVE PROGNOSIS
Authors: Krishna Saritha , Choudhury Abrar , Ni Lijun , Seo Kyounghee , Kakaizada Sofia , Findlay Anne , Lee Anthony , Sudharshan Rasika , Cao Caroline , Venkatesh Humsa , Vogel Hannes , Phillips Joanna , Almeida Nyle , Nagarajan Srikantan , Berger Mitchel , Raleigh David , Brang David , Monje Michelle , Hervey-Jumper Shawn 
Published: December 2020

Abstract

BACKGROUND
Unlike cancers affecting many solid organs, gliomas exist within the context of complex neural circuitry. It remains unknown whether glioma-neuron interactions play a role in maintaining functional circuits underlying cognition. We test the hypothesis that malignant gliomas remodel functional circuits through glioma-neuron interactions.

METHODS
Using language processing as a model for functional circuit dynamics, we enrolled 53 patients with dominant hemisphere IDH-wild-type glioblastoma. Task related circuit dynamics were measured using electrocorticography. Magnetoencephalography measures of functional connectivity identified intratumoral connectivity (HFC) and suppressed connectivity (LFC) regions. Primary patient samples and cultures from HFC and LFC-sites were assessed by single-cell RNA sequencing, pre/post-synaptic marker expression, cocultured with murine hippocampal neurons, and induced neuron organoids. Hippocampal tumor xenografts were created. Language/survival statistics were performed to correlate with functional connectivity measures.

RESULTS
Speech production evokes neuronal population spikes within the entire area of tumor-infiltrated cortex, far beyond the cortical territory normally involved in expressive language. Primary patient samples from HFC-regions are enriched for glioblastoma cells with a synaptogenic profile as characterized by pre-and post-synaptic marker expression at both tissue and cellular levels. RNA-sequencing and proteomic analyses from HFC samples revealed a neurogenic signature including thrombospondin-1 originating from glioma cells in HFC-regions and non-tumor astrocytes in LFC-regions. HFC xenografts demonstrated increased total number of synapses. Importantly, when compared with gliomas without intratumoral functional connectivity, connected gliomas have worse language task performance (r= -0.54,p=0.03) and shorter OS (medianOS-64 weeks compared with 107-weeks,p=0.04).

CONCLUSION
Glioma infiltrated regions generate task-relevant neural responses, with speech production evoking neuronal activity throughout tumor-involved cortex in the dominant hemisphere. An enriched population of synaptogenic glioma cells are organized within functionally connected intratumoral regions and this confers negative functional and survival outcomes. Together, these findings indicate that malignant gliomas can functionally remodel neural circuitry, thereby impairing neurological function and promoting tumor progression.
TAMI-26. SINGLE-CELL TRANSCRIPTOME ANALYSIS REVEALS THAT ENDOTHELIAL TRANSFORMATION DRIVES GLIOBLASTOMA CHEMORESISTANCE VIA Wnt/β-CATENIN/MRP-1
Authors: Huang Menggui , Zhang Duo , Fan Yi 
Published: December 2020

Abstract
Therapeutic resistance remains a persistent challenge for patients with glioblastoma (GBM). Here, we report that endothelial cells (ECs) acquire transformation into mesenchymal stem cell (MSC)-like cells in GBM, driving tumor resistance to cytotoxic treatment. Single-cell transcriptome analysis identified an EC-derived cell population that robustly expresses mesenchymal genes and stem cell-associated markers, suggesting that ECs undergo mesenchymal transformation and stemness-like activation in GBM microenvironment. Furthermore, we identified a c-Met-mediated axis that induces β-catenin phosphorylation at Ser675 and Wnt signaling activation, inducing multidrug resistance-associated protein-1 (MRP-1) expression and leading to EC stemness-like activation and chemoresistance. Last, genetic ablation of β-catenin in ECs overcome GBM tumor resistance to temozolomide (TMZ) chemotherapy in vivo. Combination of Wnt inhibition and TMZ chemotherapy eliminated tumor-associated ECs, inhibited GBM growth, and increased mouse survival. These findings identified a cell plasticity-based, microenvironment-dependent mechanism that controls tumor chemoresistance, and suggest that targeting Wnt/β-catenin-mediated EC transformation and stemness activation may overcome therapeutic resistance in GBM.
TAMI-28. DIFFERENTIAL MIGRATION MECHANICS AND IMMUNE RESPONSES OF GLIOMA SUBTYPES
Authors: Shamsan Ghaidan , Liu Chao , Braman Brooke , Rathe Susan , Sarver Aaron , Ghaderi Nima , McMahon Mariah , Klank Rebecca , Tschida Barbara , McFarren Joey , Sarkaria Jann , Clark H Brent , Rosenfeld Steven , Largaespada David , Odde David 
Published: December 2020

Abstract
In Glioblastoma (GBM), tumor spreading is driven by tumor cells’ ability to infiltrate healthy brain parenchyma, which prevents complete surgical resection and contributes to tumor recurrence. GBM molecular subtypes, classical, proneural and mesenchymal, were shown to strongly correlate with specific genetic alterations (Mesenchymal: NF1; Classical: EGFRVIII; Proneural: PDGFRA). Here we tested the hypothesis that a key mechanistic difference between GBM molecular subtypes is that proneural cells are slow migrating and mesenchymal cells are fast migrating. Using Sleeping Beauty transposon system, immune-competent murine brain tumors were induced by SV40-LgT antigen in combination with either NRASG12V (NRAS) or PDGFB (PDGF) overexpression. Cross-species transcriptomic analysis revealed NRAS and PDGF-driven tumors correlate with human mesenchymal and proneural GBM, respectively. Similar to human GBM, CD44 expression was higher in NRAS tumors and, consistent with migration simulations of varying CD44 levels, ex vivo brain slice live imaging showed NRAS tumors cells migrate faster than PDGF tumors cells (random motility coefficient = 30µm2/hr vs. 2.5µm2/hr, p &lt; 0.001). Consistent with CD44 function as an adhesion molecule, migration phenotype was independent of the tumor microenvironment. NRAS and human PDX/MES tumor cells were found to migrate faster and have larger cell spread area than PDGF and human PDX/PN tumors cells, respectively, in healthy mouse brain slices. Furthermore, traction force microscopy revealed NRAS tumor cells generate larger traction forces than PDGF tumors cells which further supports our theoretical mechanism driving glioma migration. Despite increased migration, NRAS cohort had better survival than PDGF which was attributed to enhanced antitumoral immune response in NRAS tumors, consistent with increased immune cell infiltration found in human mesenchymal GBM. Overall our work identified a potentially actionable difference in migration mechanics between GBM subtypes and establishes an integrated biophysical modeling and experimental approach to mechanically parameterize and simulate distinct molecular subtypes in preclinical models of cancer.
TAMI-36. CONNEXIN 43 BLOCKADE INHIBITS PROLIFERATION IN IDH1-MUTANT GLIOMA CELLS
Authors: Melamed Lisa , Lee Christine , Nagashima Hiroaki , Miller Julie , Wakimoto Hiroaki , Cahill Daniel 
Published: December 2020

Abstract
IDH1-mutant gliomas are characteristically sensitive to NAD+ depletion. It is known that NAD+ can move between cells through gap junctions, which provides an opportunity for treatments that prevent NAD+ sharing across tumor cells, effectively decreasing available NAD+. Previous studies have also shown the role of connexin 43 (Cx43) in mediating communication in glioma cell networks and have identified Cx43 as a potential mediator of temozolomide resistance in glioma. We hypothesized that blocking Cx43 would prevent intercellular NAD+ sharing in IDH-mutant gliomas, causing tumor cells to be more vulnerable to metabolic NAD+ depletion via nicotinamide phosphoribosyltransferase (NAMPT) inhibitors and temozolomide (TMZ) treatment. Here, we show that blockade of Cx43 with α-connexin carboxyl-terminal (ACT1) is able to inhibit growth of patient-derived IDH1-mutant tumor cells. ACT1 sensitizes cells to TMZ and inhibits growth of IDH1-mutant gliomas via an NAD-dependent mechanism. We also found that ACT1 can be used in combination with other NAD-depleting drugs, such as NAMPT inhibitors, to enhance its effect and provide a viable therapeutic window. Overall, our results suggest that ACT1 may enhance the efficacy of treatments for IDH1-mutant tumors by blocking metabolic buffering through tumor cell gap junctions.
TAMI-41. PI3K-GAMMA INHIBITION SUPPRESSES ACCUMULATION OF GLIOBLASTOMA-ASSOCIATED MICROGLIA TO RECAPITULATE THE MICROENVIRONMENT OF EXCEPTIONAL RESPONDERS
Authors: Li Jie , Kaneda Megan , Ma Jun , Li Ming , Patel Kunal , Koga Tomoyuki , Sarver Aaron , Furnari Frank , Xu Beibei , Dhawan Sanjay , Ning Jianfang , Zhu Hua , Wu Anhua , You Gan , Jiang Tao , Venteicher Andrew , Glass Christopher , Varner Judith , Chen Clark 
Published: December 2020

Abstract

INTRODUCTION
Exceptional responders refer to the rare subset of patients who derive extraordinary benefits from a therapy compared to most treated patients. Understanding the basis for such responses represents a key pillar in the framework of precision medicine.

OBJECTIVE
Here, we examine the molecular basis underlying exceptional responses in glioblastoma patients who underwent concurrent radiation and temozolomide (TMZ) therapy.

METHODS
mRNA profiles derived from clinically annotated glioblastoma specimens were analyzed by Single sample gene set enrichment (ssGSEA) and Gene Cluster Expression Summary Score (GCESS). Key results were confirmed using cell-based assays and murine glioblastoma models.

RESULTS
Integrated, multi-platform analyses of RNA profiles derived from clinically annotated glioblastoma samples revealed decreased accumulation of microglia/macrophages in the tumor microenvironment of exceptional responders. Further analysis revealed that glioblastoma-associated microglia/macrophages secreted interleukin 11 (IL11) activate a STAT3-MYC signaling axis in glioblastoma cells. This signaling facilitated glioblastoma transition into stem cell states that confer enhanced tumorigenicity as well as resistance to the TMZ. Pharmacologic inhibition or genetic inactivation of a myeloid cell restricted isoform of PI3K, PI3K-gamma, disrupted this signaling axis by suppressing microglia/macrophage accumulation and IL11 secretion in the glioblastoma microenvironment. Mirroring the clinical outcome of exceptional responders, PI3K-gamma inhibition synergistically enhanced the anti-neoplastic effects of TMZ in orthotopic murine glioblastoma models. Moreover, inhibition or genetic inactivation of PI3K-gamma in murine glioblastoma models recapitulated expression profiles observed in clinical specimens isolated from exceptional responders.

CONCLUSIONS
Our results suggest key contributions from tumor-associated microglia/macrophages in exceptional responses and highlight the translational potential for PI3K-gamma inhibition as a glioblastoma therapy.
TAMI-42. H3K27M MUTANT GLIOMAS HIJACK A CONSERVED AND CRITICAL METABOLIC PATHWAY USED BY IDH1 MUTANT GLIOMAS TO MAINTAIN THEIR PREFERRED EPIGENETIC STATE
Authors: Chung Chan , Sweha Stefan , Pratt Drew , Tamrazi Benita , Panwalkar Pooja , Banda Adam , Bayliss Jill , Hawes Debra , Yang Fusheng , Lee Ho-Joon , Shan Mengrou , Cieslik Marcin , Qin Tingting , Werner Christian , Wahl Daniel , Lyssiotis Costas , Yadav Viveka Nand , Koschmann Carl , Chinnaiyan Arul , Blumul Stefan , Judkins Alexander , Venneti Sriram 
Published: December 2020

Abstract
H3K27M-midline gliomas are fatal tumors that mainly harbor H3.3K27M mutations resulting in global H3K27me3 reduction that impacts neuroglial-differentiation. However, the exact mechanisms by which H3.3K27M mutations promote cancer are poorly understood. Metabolic reprogramming is a hallmark of cancer and we hypothesized that H3.3K27M mutations can reprogram metabolism to support uncontrolled growth. We demonstrate that H3.3K27M-mutant cells show elevated levels of critical enzymes related to glycolysis and TCA cycle metabolism including hexokinase-2, isocitrate dehydrogenase (IDH)-1 and glutamate dehydrogenase. H3.3K27M cells also demonstrated enhanced glycolysis, glutamine and TCA-cycle metabolism accompanied by increased alpha-ketoglutarate (α-KG) production. Mutant IDH (mIDH)1/2 converts α-KG to D-2-hydroxyglutarate (D-2HG). D-2HG increases H3K27me3 by inhibiting α-KG’s function to drive H3K27-demethylases. We discovered that H3.3K27M cells use α-KG in an opposing manner to maintain low H3K27me3. Inhibiting enzymes related to α-KG generation including hexokinase-2, glutamate-dehydrogenase and wild type-IDH1 increased global H3K27me3, altered chromatin accessibility at neuroglial-differentiation factors and lowered tumor cell proliferation. In vivo inhibition of glutamine metabolism and/ or wild type-IDH1 using blood-brain barrier penetrant small molecule inhibitors increased overall survival in vivo in two independent H3.3K27M animal models (p&lt; 0.0001). H3K27M and mIDH1 were mutually exclusive in patient tumor samples and D-2HG treatment or forced-mIDH1 expression in H3.3K27M cells increased global H3K27me3 and cell death. Finally H3.3K27M and mIDH1 were synthetic lethal in vitro. Our data suggest that H3.3K27M and mIDH1 hijack a critical and conserved metabolic pathway in opposing manners to regulate global H3K27me3. These results have implications for understanding the pathogenesis of fatal H3K27M-gliomas and for developing therapeutic strategies by disruption of an integrated metabolic/epigenetic-axis.
TAMI-55. THE EVOLUTIONARY ENIGMA OF FATTY ACID DESATURATION IN GLIOBLASTOMA
Authors: Oatman Nicole , Reisz Julie , D’Alessandro Angelo , Dasgupta Biplab 
Published: December 2020

Abstract
Fatty acid desaturation is an enzymatic reaction in which a double bond is introduced into an acyl chain. Of the four functionally distinct desaturase subfamilies, the First Desaturase Family of enzymes introduce the first double bond into a saturated fatty acid, resulting in the synthesis of monounsaturated fatty acids (MUFA). MUFA are essential components of membrane and storage lipids and exert a profound influence on the fluidity of biological membranes. A disequilibrium in saturated to unsaturated fatty acid ratio alters cell growth, differentiation and response to external stimuli, and thus affects a range of pathologies including cancer. The most abundant and key First Desaturase Family enzyme is the delta 9 desaturate called Stearoyl Co-A Desaturase (SCD and SCD5 in humans, and SCD1-4 in mice). SCD desaturates Stearoyl-CoA (C18) and palmitoyl-CoA (C16) to oleoyl-CoA (C18:1) and palmitoyl-CoA (C16:1), respectively. Besides SCD, the only known First Desaturase in mammals with dual function is FADS2 which desaturates palmitate to Sapienate (C16:1, a positional isomer of palmitoleate) in skin cells. A recent study showed that some cancer cells can use FADS2 to bypass the SCD reaction. SCD and SCD5 are by far the most abundant desaturases expressed in the human brain. We made an unexpected discovery that SCD undergoes monoallelic codeletion with PTEN on chromosome 10, and is also highly methylated in glioblastoma (GBM). More surprisingly, all GBM cell lines with SCD codeletion/methylation (that expressed very little SCD protein) are completely resistant to SCD/SCD5 inhibition, yet their phospholipids contained abundant oleic acid. It is unknown if GBMs bypassed SCD, but retained the delta 9 desaturation reaction through a novel enzymatic activity. Our targeted and untargeted metabolomics studies revealed unexpected findings that cannot be explained by conventional wisdom, and may lead to identification of novel lipogenic targets in GBM.
TAMI-56. HYPOXIA-DRIVEN NECROSIS DRIVES DYNAMIC TUMOR PROGRESSION IN GLIOBLASTOMA
Authors: Markwell Steven , Olson Cheryl , Ross James , Nunez-Santana Felix , Brat Daniel 
Published: December 2020

Abstract
The onset of necrosis correlates with aggressive malignant progression in solid tumors. Whether necrosis arises from or promotes accelerated tumor proliferation and progression remains unknown, primarily due to inadequate models systems that fail to induce or capture these dynamic changes as they develop. In glioblastoma (GBM; WHO grade IV), the most malignant primary brain tumor, vascular pathology and central necrosis precedes rapid, radial expansion resulting in patient mortality. While genetic alterations in GBM have been highly characterized, biological adaptations arising from sustained hypoxia/anoxia require further mechanistic investigation. This sustained nutrient deprivation leads to necrosis which dramatically changes the tumor microenvironment (TME). To reveal the dynamic temporal and spatial changes promoting expansive progression, we are generating mouse models that more appropriately capture events found in human gliomas, accounting for unique microenvironmental stressors often lacking in GBM animal models, specifically central necrosis. Combining hypoxia-induced focal necrosis within high grade gliomas with intravital microscopy captures TME restructuring to understand its impact on glioma progression. Our studies use both genetically characterized patient-derived orthotopic GBM xenografts, alongside an immunocompetent RCAS/tv-a model, to determine how antagonizing these processes impacts disease progression and outcomes across multiple GBM subtypes. Complementary to this, we are investigating how increasing hypoxia and necrosis-driven signaling events promotes tumor-associated macrophages (TAMs) influx and reprogramming during glioma progression. Our preliminary data indicate substantial differences pre- and post-necrosis regarding TAM enrichment, immunosuppressive phenotypic conversion and their biological impact, however these mechanisms have not yet been elucidated. Our models capture glioma growth dynamics, reactive neuroinflammation and therapeutic resistance, facilitating innovative pre-clinical interventions to improve patient outcome.
TAMI-61. TUMOR-ASSOCIATED MACROPHAGES ARE INDEPENDENT PROGNOSTIC MARKERS IN MENINGIOMAS
Authors: Liu Fang , Jungwirth Gerhard , Warta Rolf , Unterberg Andreas , Herold-Mende Christel 
Published: December 2020

Abstract
Tumor-associated macrophages (TAMs) play an emerging role in tumor progression by creating an immunosuppressive tumor microenvironment. Therefore, we investigated TAM numbers and their activation (M1/2) in primary (p-) and recurrent (r-) meningiomas and evaluated their impact on survival. Presence of TAMs was analyzed in 195 clinically well-annotated cases (WHO°I n = 43, WHO°II n = 95, WHO°III n = 57; pMGM n = 120, rMGM n = 75). TAMs were quantified by a semiautomated analysis on whole tissue sections stained by multicolor immunofluorescence for CD68 as general TAM marker, and for CD163 and CD204 as M2 marker. CD68+ macrophages positive for either CD163 or CD204 were regarded as M2-polarized TAMs. Furthermore, concentration of 27 immune-relevant cytokines and chemokines from meningioma tissue samples (n = 46) were assessed by Luminex analysis. Median TAM infiltration accounted for 2.47% per total cell count in pMGM and 3.22% in rMGMs. Although no significant WHO°-dependent changes regarding TAM numbers were observed, high numbers of TAMs were associated with shorter progression-free survival (PFS) independent of prognostic confounding variables such as WHO, sex and age. In pMGMs, proportion of M2-polarized TAMs was significantly increased in WHO°II and WHO°III tumors compared to WHO°I (P = 0.001 and P = 0.03, respectively). Luminex data revealed a WHO°-dependent increase of IL-8, IL-10, and IL-12p70. Tissue samples containing higher numbers of TAMs demonstrated significant elevated concentrations of interleukin-1 family members (IL-1β, IL-1Ra), and G-CSF. Furthermore, upregulation of IL-1β and IL-1Ra resulted in shorter overall survival of patients (P = 0.049, P = 0.006, respectively). Taken together, we identified higher numbers of TAMs as an independent prognostic factor for shorter progression-free survival in meningioma patients. This was associated with increased levels of the interleukin-1 family members IL-1β and IL-1Ra and a shorter overall survival, indicating an important function in the tumor microenvironment.
TMOD-05. EXTRACRANIAL TUMORS INFLUENCE INTRACRANIAL RESPONSE TO IMMUNE CHECKPOINT INHIBITORS IN PRE-CLINICAL MODELS OF MELANOMA BRAIN METASTASIS
Authors: Nayyar Naema , Singh Mohini , Stocking Jackson , Brehm Michael , Brastianos Priscilla 
Published: December 2020

Abstract
Melanomas frequently spread to the brain, with up to 75% of patients developing brain metastases. Treatment of metastatic melanoma has been revolutionized by the advent of immune checkpoint inhibitors (ICI) targeting PD-1 and CTLA-4. However, responses to ICI within the immune-specialized brain environment are not well understood owing to the lack of immunocompetent animal models for the investigation of intracranial responses to checkpoint blockade. We studied the effect of ICI in a syngeneic mouse model of melanoma brain metastasis with concurrent intracranial and subcutaneous tumors. Either D3UV3 cells, derived from a UVB irradiated clone of D4M.3A melanoma cell line, or vehicle were subcutaneously injected into the flank of C57BL/6 mice. 3 days later, D3UV3 cells tagged with firefly luciferase were implanted into the striatum using stereotactic injection. Mice were then treated with anti-PD-1 antibody, anti-CTLA-4 antibody, a combination of anti-PD-1 and anti-CTLA-4 antibodies, or isotype controls. We observed striking differences in survival between mice with concurrent intracranial and subcutaneous tumors compared to intracranial tumors alone. Mice with intracranial tumors alone experienced no benefit in survival following monotherapy with anti-PD-1 (p=1) or anti-CTLA-4 (p=0.1) compared to isotype-treated mice, and only a slight benefit with combination treatment (p=0.049). In contrast, mice with concurrent tumors experienced a significant increase in overall survival with anti-CTLA-4 monotherapy (p=0.01) and combination anti-CTLA-4 and anti-PD-1 treatment (p=0.01) compared to isotype-treated mice, although treatment with anti-PD-1 alone did not increase survival (p=0.28). These results indicate that the presence of extracranial disease can modulate intracranial immune responses following checkpoint blockade. We have therefore established a pre-clinical model with concurrent intracranial and extracranial tumors to better recapitulate the clinically observed context of brain metastases. We hope this model will lead to a better understanding of the setting in which ICI is effective for patients with melanoma brain metastases.