bluuebunny/crossref_metadata_2025_split huggingface dataset:
STEM-03. Oct4/Sox2 DRIVE AN IMMUNOSUPPRESSIVE GSC PHENOTYPE BY INDUCING T-REG EFFECTOR GENES VIA TGFBR2 SIGNALING
Authors: Johnson Amanda , Korleski Jack , Laterra John , Lopez-Bertoni Hernando 
Published: November 2021

Abstract
Solid malignancies, including GBM, contain small subsets of cells that display stem-like properties (i.e. glioma stem cells or GSCs) and act as key determinants of therapeutic resistance and tumor recurrence. Mechanisms of GSC immune escape are considered fundamental to clinical GBM growth and recurrence. GBM cells escape antitumor immunity by modifying the tumor microenvironment by secreting immune-suppressive factors and recruiting anti-inflammatory/pro-oncogenic cells (e.g. T-regulatory cells, M2-like macrophages). However, whether subsets of GSCs can mimic T-reg-like functions by expressing proteins associated with T-reg immune-suppression remains unknown. Single-cell RNA sequencing analysis of GBM neurospheres revealed a previously unrecognized Oct4/Sox2high/FOXP3- cell subpopulation with high expression of TGFb1, CD39, CD73, PD-L1, and Galectin-1, a gene expression fingerprint typically associated with T-reg cells and their immune suppressive functions within the tumor microenvironment. Bioinformatics analysis of public databases shows that the above-mentioned genes are enriched in the mesenchymal GBM subtype and highly correlated with CD44 and TGFb type II receptor (TGFBR2) expression in both clinical GBM and primary GSCs. Mechanistically, Oct4 and Sox2 were found to directly induce TGFBR2 transcription concurrent with chromatin architectural changes (i.e. heterochromatin-to-euchromatin transition) involving the TGFBR2 gene. Transgenic TGFBR2 expression increased neurosphere cell growth capacity, upregulated expression of T-reg-like effector genes and enriched for CD44+ GSCs. Functionally, neurospheres expressing transgenic Oct4/Sox2 or transgenic TGFBR2 possess increased immunosuppressive capacity, and pharmacological inhibition of TGFBR2 depleted CD44+ GSCs and reduced immunosuppression in Jurkat cell co-cultures. Taken together, we show that reprogramming events initiated by Oct4 and Sox2 induce a CD44+/FOX3P- GSC cell subset with a T-reg-like immunosuppressive transcriptional profile via a TGFBR2-dependent mechanism. This research provides the first description of such neoplastic cells in any malignancy and has high potential translational impact since targeting these tumor cell subsets and their immunosuppressive mechanisms may be critical to the successful development of GBM immunotherapies.
STEM-04. PD-1 INDEPENDENT OF PD-L1 LIGATION PROMOTES GLIOBLASTOMA GROWTH THROUGH THE NFkB PATHWAY
Authors: Mirzaei Reza , Yong Wee 
Published: November 2021

Abstract
Brain tumor-initiating cells (BTICs) drive glioblastoma growth through not fully understood mechanisms. Here, we found that a proportion of human and murine BTICs expressed programmed cell death protein (PD-1). Gain- or loss-of-function studies revealed that tumor-intrinsic PD-1 promoted proliferation, and self-renewal of BTICs. Mechanistically, site-directed mutagenesis, RNA sequencing and pharmacological inhibitors implicated SHP-2-mediated activation of NFkB downstream of PD-1 in BTICs. Notably, the tumor-intrinsic promoting effects of PD-1 did not require PD-L1 ligation; thus, the therapeutic blocking antibodies inhibiting PD-1/PD-L1 interaction which failed in glioblastoma trials could not overcome the growth advantage of PD-1 in BTICs. Finally, mice with intracranial Pdcd1 over- or underexpressing BTICs had shorter or longer survival, respectively, and this occurred in mice lacking T and B cells. These findings point to a critical role for PD-1 in BTICs and uncover a non-immune resistance mechanism of GBM patients to PD-1 or PD-L1 blocking therapies.
STEM-05. FUNCTIONAL MAPPING REVEALS WIDESPREAD REMODELLING AND UNRECOGNIZED PATHWAY DEPENDENCIES IN RECURRENT GLIOBLASTOMA
Authors: Chokshi Chirayu R , Tieu David , Brown Kevin R , Venugopal Chitra , Liu Lina , Kuhlmann Laura , Rossotti Martin A , Chan Katherine , Tong Amy H Y , Savage Neil , McKenna Dillon , Aghaei Nikoo , Subapanditha Minomi , Vaseem Shaikh Muhammad , Tatari Nazanin , Brakel Benjamin , Nachmani Omri , Ignatchenko Vladimir , Salamoun Joseph M , Wipf Peter , Sharlow Elizabeth , Provias John P , Lu Jian-Qiang , Murty Naresh K , Lazo John S , Kislinger Thomas , Henry Kevin A , Lu Yu , Moffat Jason , Singh Sheila K 
Published: November 2021

Abstract
Resistance to genotoxic therapies and tumor recurrence are hallmarks of glioblastoma (GBM), an aggressive brain tumor. Here, we explore the functional drivers of post-treatment recurrent GBM. By conducting genome-wide CRISPR-Cas9 screens in patient-derived GBM models, we uncover distinct genetic dependencies in recurrent tumor cells that were absent in their patient-matched primary predecessors, accompanied by increased mutational burden and differential transcript and protein expression. These analyses support parallel tumor-intrinsic mechanisms of treatment resistance which rely on acquisition of immunosuppressive capacity, including a defective mismatch repair pathway, ablation of PTEN activity, and a novel combination of de novo mutations in SWI/SNF components. We map a multilayered genetic and functional response to resist chemoradiotherapy and drive tumor recurrence, identifying protein tyrosine phosphatase 4A2 (PTP4A2) as a novel driver of self-renewal, proliferation and tumorigenicity at GBM recurrence. Mechanistically, genetic perturbation and a small molecule inhibitor of PTP4A2 repress axon guidance activity through a dephosphorylation axis with roundabout guidance receptor 1 (ROBO1) and exploit a genetic dependency on ROBO signaling. Importantly, engineered anti-ROBO1 single-domain antibodies also mimic the effects of PTP4A2 inhibition. We conclude that functional reprogramming drives tumorigenicity and present a dependence on a PTP4A2-ROBO1 signaling axis at GBM recurrence.
STEM-08. ST6Gal1-MEDIATED SILALYLATION IS CRITICAL FOR GLIOBLASTOMA GROWTH
Authors: GC Sajina , Tuy Kaysaw , Rickenbacker Lucas , Jones Brent , Chakraborty Asmi , Miller Ryan , Liu Xiaoguang , Mobley James , Bellis Susan , Hjelmeland Anita 
Published: November 2021

Abstract
Although altered cell surface glycosylation was one of the earliest modifications observed in neoplastic progression, this facet of cancer cell biology has received meager attention, particularly in brain tumors. Among the various glycosyltransferases present in human cells, golgi sialyltransferase ST6Gal1 [beta-galactoside alpha-2,6-sialyltransferase 1] adds sialic acid residues in α2-6 linkage to membrane-bound and secreted N-glycans. ST6Gal1 is known to be pro-tumorigenic in epithelial cancers where it can promote epithelial to mesenchymal transformation, tumor-initiating cell (TIC) phenotypes, and survival of cells exposed to stressors such as chemo- and radiotherapy, hypoxia, or serum starvation. However, roles for this potent TIC regulator have not been well explored in GBM as experiments in standard cell lines suggested ST6Gal1 was epigenetically silenced. To explore our hypothesis that ST6Gal1-mediated α2,6 sialylation is elevated in Brain Tumor Initiating Cells (BTICs) and promotes GBM growth, we utilized GBM patient-derived xenografts (PDXs). ST6Gal1 is expressed in GBM PDX tissue sections and elevated in stem-like BTICs in comparison to differentiated GBM cells or astrocytes. Knockdown of ST6Gal1 in BTICs decreased growth and neurosphere formation capacity in vitro, suggesting that ST6Gal1 regulates BTIC maintenance. Similarly, cells isolated directly from PDXs that were sorted for high and low expression of α2,6 sialylation showed that α2,6 sialylationhigh GBM PDX have elevated neurosphere formation capacity and growth. Further, immunocompromised mice injected with sorted α2,6 sialylationhigh PDX cells had significantly lower survival compared to mice injected with α2,6 sialylationlow cells. Using proteomic analysis of ST6Gal1 KD vs NT PDX, we identified novel regulators of cancer stem cell biology directly modulated by ST6Gal1. As we identified a small subset of IDHwt GBMs with ST6Gal1 and SOX2 amplification, we are generating a novel gliomagenesis model with conditional ST6Gal1 overexpression. Together, our data strongly implicates ST6Gal1 as a regulator of GBM BTIC maintenance and GBM growth.
STEM-09. DEFINING THE ROLE OF CD97 IN GLIOBLASTOMA STEM CELL SELF-RENEWAL
Authors: Ravn-Boess Niklas , Bhowmick Nainita , Hattori Takamitsu , Corrado Alexis , Koide Akiko , Karimkhan Afreen , Koide Shohei , Park Christopher , Placantonakis Dimitris 
Published: November 2021

Abstract
Glioblastoma (GBM) is the most common and aggressive primary brain malignancy. Despite multimodal therapy, resistant GBM stem-like cells (GSCs) inevitably mediate disease recurrence. To identify novel vulnerabilities of GSCs, we performed an arrayed CRISPR/Cas9 screen against select adhesion G protein-coupled receptors (aGPCRs), many of which we found to be de novo expressed in GBM. Knockout of CD97 (ADGRE5), previously implicated in GBM cell migration, produced the most striking proliferative disadvantage in patient-derived GBM cultures (PDGC) among aGPCRs tested. We found high CD97 surface expression in all our PDGCs, while levels remained nearly undetectable in non-neoplastic brain cells, confirming that CD97 is de novo expressed in GBM. Upon shRNA-mediated knockdown of CD97 in PDGCs from all three TCGA transcriptional subtypes, we observed significantly reduced proliferation, as measured by Ki67 and Hoechst cell cycle analysis, and significantly diminished surface expression of CD133, a GSC marker. Notably, CD97 knockdown also significantly reduced tumorsphere initiation capacity in six PDGCs, as measured by extreme limiting dilution assays. These findings suggest that CD97 regulates GSC self-renewal in vitro. RNA-sequencing and GSEA pathway analysis from PDGCs following CD97 knockdown indicate an enrichment of aerobic respiratory gene sets, suggesting one of the major regulatory roles of CD97 is metabolic regulation. Indeed, metabolic assays show that CD97 knockdown alters oxygen consumption and glycolysis rates in PDGCs. Lastly, we have developed human synthetic antibodies to target CD97 in order to investigate its therapeutic potential. We have observed internalization of some of these antibodies, thus identifying candidates for the development of antibody-drug conjugates. In addition, other clones reduced GBM cell proliferation and elicited expression of various differentiation markers. Overall; our studies identify novel roles of CD97 in regulating the cellular hierarchy in GBM and tumor cell metabolism, and provide a strong scientific rationale for developing biologics to target CD97 in GBM.
STEM-14. THE WRAD COMPLEX REPRESENTS A THERAPEUTIC TARGET FOR CANCER STEM CELLS IN GLIOBLASTOMA
Authors: Mitchell Kelly , Alvarado Joseph , Goins Christopher , Martinez Steven , Macdonald Jonathan , Silver Daniel J , Roversi Gustavo , Kay Kristen , Schafer Rachel , Kashyap Anjali , Lauko Adam , Mulkearns-Hubert Erin E , Johnson Sadie , Rich Jeremy N , Stauffer Shaun , Hubert Christopher , Lathia Justin 
Published: November 2021

Abstract
Glioblastoma (GBM) progression and resistance to conventional therapies is driven in part by cells within the tumor with stem cell properties including quiescence, self-renewal and drug efflux potential. It is thought that eliminating these cancer stem cells (CSCs) is a key component to successful clinical management of GBM. However, currently, few known molecular mechanisms driving CSCs can be exploited for therapeutic development. Core transcription factors such as SOX2, OLIG2, OCT4 and NANOG maintain the CSC state in GBM. Our laboratory recently uncovered a self-renewal signaling axis involving RBBP5 that is necessary and sufficient for CSC maintenance through driving expression of these core stem cell maintenance transcription factors. RBBP5 is a component of the WRAD complex, which promotes Lys4 methylation of histone H3 to positively regulate transcription. We hypothesized that targeting RBBP5 could be a means to disrupt epigenetic programs that maintain CSCs in stemness transcriptional states. We found that genetic and pharmacologic inhibition of the WRAD complex reduced CSC growth, self-renewal and tumor initiation potential. WRAD inhibitors partially dissembled the WRAD complex and reduced H3K4 trimethylation both globally and at the promoters of key stem cell maintenance transcription factors. Using a CSC reporter system, we demonstrated that WRAD complex inhibition decreased growth of SOX2/OCT4 expressing CSCs in a concentration-dependent manner as quantified by live imaging. Overall, our studies assess the function of the WRAD complex and the effect of WRAD complex inhibitors in preclinical models and specifically on the stem cell state for the first time in GBM. Studying the functions of the WRAD complex in CSCs may improve understanding of GBM pathogenesis and elucidate how CSCs survive despite aggressive chemotherapy and radiation. Our ongoing studies aim to develop brain penetrant inhibitors targeting the WRAD complex as an anti-CSC strategy that could potentially synergize with standard of care treatments.
STEM-21. INHIBITING ADENINE SYNTHESIS ATTENUATES GLIOBLASTOMA CELL STEMNESS AND TEMOZOLOMIDE RESISTANCE
Authors: Singh Simranjit , Hansen Landon , Du Changzheng , Roso Kristen , Yang Rui , Greer Paula , He Yiping 
Published: November 2021

Abstract
Glioblastoma (GBM) is a lethal brain cancer that exhibits high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work has shown that homozygous MTAP deletion, a frequent genetic alteration in GBM, promotes the stemness of GBM cells. Here, exploiting the MTAP loss-conferred deficiency in adenine salvage, we demonstrated that subtle levels of adenine blockade via treatment with Alanosine, an inhibitor of de novo adenine synthesis, attenuate the stemness of MTAP-null GBM cells. Transcriptomic profiling performed on Alanosine-treated GBM cells revealed a reduction of mitochondrial DNA-encoded gene expression. Furthermore, Seahorse XF analysis showed that Alanosine treatment led to a reduction in mitochondrial respiration and eliminated GBM cells’ spare respiratory capacity, an important metabolic measure of cell fitness that is representative of their ability to respond to oxidative stress. Importantly, long term adenine shortage via treatment with low doses of Alanosine resulted in similarly compromised mitochondria functionality and attenuated GBM cells’ stemness. In further supporting this adenine blockade – compromised mitochondria – reduced stemness cascade, treatment with a mitochondrial respiration inhibitor attenuated the stemness of GBM cells, suggesting the importance of mitochondrial function in maintaining GBM stemness. Finally, in agreement with the diminished stemness and compromised mitochondrial function, we showed that Alanosine sensitized GBM cells to temozolomide (TMZ) in both in vitro cultures and in an orthotopic GBM model. Collectively, these results identify critical roles of adenine supply in maintaining stemness and mitochondrial function in GBM cells, suggest a targeted method of abrogating stemness and chemoresistance in GBMs, and support targeting adenine synthesis as a complementary approach for treating the half of GBMs harboring MTAP deletions.
STEM-23. LncRNA HOTAIR SPONGES miR301a-3p TO PROMOTE GLIOMA’S PROLIFERATION AND INVASION THROUGH THE ACTIVATION OF FosL1
Authors: King Pendelton , Guo Alyssa , Wan Jingwei , Liu Mingli 
Published: November 2021

Abstract

BACKGROUND
Non-coding RNAs, including LncRNAs, function in regulating glioblastomas’ numerous oncogenic phenotypes, such as invasiveness and stemness of glioblastoma stem cells. These LncRNAs contain long non-encoding RNA transcripts &gt;200 nucleotides in length, many of which show cell type-specific expression. In this project, we investigated how TRPM7, a promoter for glioma’s proliferation and invasion, regulates LncRNA and contributes to glioma tumorigenesis.

METHODS
1) Total RNA, from either with A172 glioma cells or A172 glioma cells with TRPM7 knocked out (A172 KO), were extracted and then parallelly subjected to Human Cancer Pathway Finder, RT2 LncRNA PCR Array. 2) We then analyzed the prognostic role of LncRNAs using a publicly available bioinformatics data set (www.Oncolanc.org). 3) We examined the effects of TRPM7-regulated LncRNA, and its downstream molecules miR301a-3p and FosL1 oncogene, on the proliferation and invasion of glioma cells in A172 and PDX-L12 cells by either inhibition or activation of the above molecules.

RESULTS
1) Data analysis from RT2 data resulted in a list of 10 downregulated and 7 upregulated LncRNAs whose transcripts are statistically significant with fold changes greater than 2.0 by TRPM7 knockout. 2) The results showed that TRPM7 functions as a positive regulator of LncRNA, HOTAIR, which is an unfavorable prognostic factor of 7-year overall survival in glioma patients. 3) In addition, we found that LncRNA HOTAIR sponges miR-301a-3p to promote proliferation, invasion, and stemness of glioma through upregulating the oncogene FosL1. 4) Furthermore, we identified that FosL1 is a novel prognostic marker of glioma patients.

CONCLUSION
Our results demonstrated the role of TRPM7-regulated LncRNA HOTAIR as a miRNA sponge in glioma, which shed new light on LncRNA-directed therapeutics in glioma.
STEM-26. BLOOD-TUMOR BARRIER IS COMPOSED OF MECHANOSENSING TUMOR CELLS THAT MASK THERAPEUTIC VULNERABILITY
Authors: Momin Ali , Chen Xin , Wang Gousiyi , Wang Xian , Min Hyun-Kee , Dou Wenkun , Gong Zheyuan , Chan Jade , Chen Yuki , Veerasammy Kelly , Dong Weifan , Fan Jerry , Fekete Adam , Dou Zhengchao , Hu Malini , Pardis Parnian , Kumar Sachin , Juraschka Kyle , Donovan Laura , Dirks Peter , Taylor Michael D , Wang Lu-Yang , Hui Chi-chung , Abzalimov Rinat , He Ye , Sun Yu , Li Xuejun , Huang Xi 
Published: November 2021

Abstract
Two major obstacles in brain cancer treatment are the blood-tumor barrier (BTB), which restricts delivery of most therapeutic agents, and the quiescent brain tumor-initiating cells (BTICs), which evade cell cycle-targeting chemotherapy. Mechanosensation, the transduction of mechanical cues into cellular signaling, underlies physiological processes such as touch, pain, proprioception, hearing, respiration, epithelial homeostasis, and vascular and lymphatic development. We report that medulloblastoma (MB) BTICs are mechanosensing, a property conferred by force-activated ion channel Piezo2. In contrast to the prevailing view that astrocytes function as a physical barrier in BTB, BTICs project endfeet to ensheathe capillaries. MB develops a tissue stiffness gradient as a function of distance to capillaries. Piezo2 senses substrate stiffness to sustain local intracellular calcium, actomyosin tension, and adhesion at BTIC growth cones, which allow BTICs to mechanically interact with their substrate and sequester β-Catenin to prevent WNT/β-Catenin signaling in BTICs. Our single cell analysis uncovers a two-branched BTIC trajectory that progresses from a deep quiescent state to two cycling states. Tumor cell-specific Piezo2 knockout reverses the off-on WNT/β-Catenin signaling states in BTICs and endothelial cells, collapses the BTB, reduces quiescence depth of BTICs, and markedly enhances MB response to chemotherapy. Our study reveals that BTICs co-opt astrocytic mechanism to contribute to the BTB and provides the first evidence that BTB depends on mechanochemical signaling to mask tumor chemosensitivity. Targeting Piezo2 addresses BTB and BTIC properties that underlie therapy failures in brain cancer.
CBIO-01. INHIBITION OF EXTRACELLULAR CARBONIC ANHYDRASES INHIBITS GLIOBLASTOMA CELL INVASION
Authors: Proescholdt Martin , Qiu Zhenwei , Falter Johannes , Lohmeier Anette , Schmidt Nils-Ole 
Published: November 2021

Abstract

BACKGROUND
Malignant gliomas metabolize glucose preferably by glycolysis which is in accordance with the Warburg effect. This induces a high demand of glucose combined with a significant lactic acid load. The hypoxia-inducible carbonic anhydrase (CA) IX has been shown to moderate the extrusion of hydrogen ions into the extracellular space. Since the acidification of the extracellular environment contributes to host tissue invasion due to activation of proteolytic enzymes, we hypothesized that CA IX plays an important role in malignant glioma Recently, specific small molecule inhibitors of this enzyme have been developed and may provide an innovative strategy for anti – invasive treatment.

METHODS
Two established and 4 primary GBM cell lines (2 with mesenchymal and 2 with proneural transcriptional profile) were exposed to the CAIX inhibitor U104 under normoxic and hypoxic conditions. Cell toxicity was measured by ATP and crystal violet assay. For invasion assessment, a matrigel invasion chamber system with 8 µm pore size polycarbonate filter was used. CAIX expression was analyzed by quantitative RTPCR and Western Blot.

RESULTS
Hypoxia significantly induced CAIX expression in all cell lines. Invasiveness increased significantly under hypoxic conditions in the mesenchymal cells (p &lt; 0.01). Regardless of oxygenation status, the mesenchymal group displayed significantly higher invasiveness compared to the proneural group (p = 0.006). Looking at all cell lines, invasion is significantly inhibited by U104, both under normoxic and hypoxic conditions (p &lt; 0.01). However, while the mesenchymal group showed the highest susceptibility to CAIX inhibition followed by the proneurally differentiated group, the established cell lines were entirely refractory to CAIX inhibition.

CONCLUSION
Our data demonstrate that CAIX inhibition can effectively inhibit invasion in malignant glioma cells independent from oxygenation status, however the effects are significantly influenced by cell type specific biological features.
CBIO-03. A COMPREHENSIVE CHARACTERIZATION OF THE GBM LIPIDOME REVEALS A MOLECULARLY-DEFINED SUB-GROUP WITH HEIGHTENED SENSITIVITY TO FERROPTOSIS
Authors: Morrow Danielle , Minami Jenna , Bayley Nicholas , Williams Kevin , Prins Robert , Liau Linda , Cloughesy Timothy , Bensinger Steven , Nathanson David 
Published: November 2021

Abstract
Cancers, including the universally lethal glioblastoma (GBM), have reprogrammed lipid metabolism to fuel tumor growth. However, the molecular alterations responsible for aberrant lipid metabolism, and the potential for identifying new therapeutic opportunities are not fully understood. To systematically investigate the GBM lipidome, we performed integrated transcriptomic, genomic and shotgun lipidomic analysis of an extensive library of molecularly diverse patient-derived GBM tumors and model systems. Using this comprehensive approach, we discovered two GBM sub-groups defined by their combined molecular and lipidomic profile. Among the most significant differences between the two groups were lipid length and desaturation. As a consequence of this signature, a subset was more sensitive to lipid peroxidation and ferroptosis. Our findings suggest a novel association between specific molecular signatures of GBM, lipid metabolism and lipid peroxidation-induced cell death. This relationship may present a new therapeutic opportunity to target reprogrammed lipid metabolism in a molecularly-defined subset of GBMs.