bluuebunny/crossref_metadata_2025_split huggingface dataset:
CNSC-34. BAF60C/SMARCD3 MODULATES CEREBELLUM DEVELOPMENT AND MEDULLOBLASTOMA METASTASIS
Authors: Zou Han , Patel, Yash , Sneiderman Chaim , Talluru Anjali , Zheng Allen , Pearce Thomas , Agnihotri Sameer , Kohanbash Gary , Pollack Ian , Hu Baoli 
Published: November 2023

Abstract
Medulloblastoma (MB), the most common type of embryonal tumor in children, is a fast-growing and heterogeneous brain tumor arising in the cerebellum. The molecular characterization of MB reveals four major subgroups (WNT, SHH, Group 3, and Group 4) and Group 3 is the most aggressive and malignant, characterized by frequent metastasis at diagnosis and the worst prognosis. We have recently found that BAF60C/SMARCD3 is highly expressed in Group 3 MB and associated with poor prognosis. Mechanistically, BAF60C/SMARCD3 hijacks a neurodevelopmental epigenetic program mediated by Disabled1 (DAB1)-Reelin signaling to promote metastatic dissemination in MB. Using single-cell RNA sequencing data of developing mouse and human cerebellum, we found that BAF60C/SMARCD3 expression in Purkinje cells (PCs) is upregulated during embryonic and early postnatal stages, but downregulated during the late postnatal stage of cerebellar development. To examine the effect of BAF60C/SMARCD3 depletion on PC migration and positioning during embryonic and postnatal stages of cerebellar development, we generated targeted knockout mice by crossing the PC-specific Cre mouse (L7Cre-2 and FoxP2-Cre) with the Smarcd3flox/flox mouse. We found that BAF60C/SMARCD3 depletion significantly influences embryo development in FoxP2-Cre; Smarcd3flox/flox but not in L7Cre-2; Smarcd3flox/flox mice, further supporting the expression of BAF60C/SMARCD3 in early stage (Foxp2 +) but not in the late stage (L7/Pcp2+) during cerebellum development. To determine whether BAF60C/SMARCD3 contributes to MB development, we injected lentivirus-carrying constitutively active MYCS62D with/without BAF60C/SMARCD3 in C57BL/6J mice. Interestingly, we found that MYCS62D with BAF60C/SMARCD3 can induce a spontaneous Group3-like MB with strong metastatic dissemination compared to MYCS62D without BAF60C/SMARCD3. These results demonstrate that BAF60C/SMARCD3 plays a pivotal role in PC biology and cerebellar development, and tumor cells hijack BAF60C/SMARCD3-Reelin signaling to promote tumor metastasis in MB.
STEM-04. FATE-BASED CONVERSION FOR IN SITU VACCINATION IN GLIOBLASTOMA
Authors: Tran David , Liu Tianyi , Jin Dan , Le Son , Chen Dongjiang 
Published: November 2023

Abstract

BACKGROUND
Although immune checkpoint inhibitors have shown high benefit for other solid tumors, their efficacy is limited in GBM due in large part to the “cold” tumor microenvironment (TME) of the GBM tumor. New approaches are necessary to overcome these challenges. We propose a shift in the scientific and treatment paradigm of cancer immunotherapy, calling for tumor cells to take on a central, active role in initiating their own immunity right in the TME.

METHODS
Using AI, we identified cell fate determinants (CFDs) to convert GBM cells directly into induced dendritic cells (iDC) inside the TME. CFDs were delivered using a viral vector and conversion assessed by immunophenotyping, scRNA-seq, and functional assays for classical DC properties.

RESULTS
A four-CFD subnetwork anchored by PU.1 was sufficient to convert mouse GBM cells to iDCs (CD45+MHCII+CD80/86+MHCI+). iDCs are growth arrested, exhibit 3-fold higher phagocytic activity and upregulate the canonical antigen processing and presenting machineries by 10-40-fold, resulting in 100-fold greater efficiency at processing ovalbumin and cross-presenting SIINFEKL to naive OTI-CD8+ cytotoxic T lymphocytes (CTL). In addition, iDCs efficiently cross-present exogenous antigens to naïve CD8+ CTLs and elicit &gt;30-fold higher activation and cytotoxicity in tumor-specific T cells compared to native GBM cells, confirming their DC-like properties. Lastly, intratumoral GBM-DC conversion in a syngeneic orthotopic GBM model resulted in significant reduction in tumor burden and increase in survival compared to controls (Log-rank, p = 0.01) with synergistic efficacy with ICIs and classical DC-based tumor vaccination. We have also successfully converted human GBM cells to iDCs with similar properties using a 2-CFD combination also anchored by PU.1.

CONCLUSIONS
GBM-derived iDCs acquired DC-like functions and were capable of eliciting robust intratumor immune activation, thereby overcoming many current limitations of immunotherapy in GBM. Our goal is to develop a low cost, off-the-shelf gene therapy-based fate conversion tumor immunotherapy.
STEM-08. OVERCOMING GLIOBLASTOMA STEM CELL RESISTANCE TO RADIATION THROUGH TARGETING THIOREDOXIN REDUCTASE 1
Authors: Jamali Fatemeh , Lan Katherine , Sabri Siham , Abdulkarim Bassam 
Published: November 2023

Abstract
Glioblastoma, the most aggressive primary tumor of the central nervous system, presents challenges due to its resistance to standard treatment, including radiation therapy (RT). Glioblastoma stem cells (GSCs), known for their chemo-radioresistance, employ adaptive mechanisms to counteract therapy-induced reactive oxygen species (ROS) levels. This includes modulating the activity of thioredoxin (Trx), a key player in the redox system. Furthermore, GSCs exhibit enhanced DNA repair capacity by upregulating DNA repair proteins, such as RAD51 to survive following ROS-induced DNA damage in response to radiation. Our TCGA analysis revealed elevated expression of thioredoxin reductase 1 (TrxR1) in patients diagnosed with GBM and a significant positive correlation between TrxR1 and RAD51. We hypothesized that GSCs might enhance their antioxidant capacity following RT to suppress RT-induced ROS elevation. Hence, combining RT with TrxR1 inhibitors might overcome GSCs radioresistance while reducing RAD51 expression. Auranofin (Au), a drug FDA-approved for rheumatoid arthritis inhibits TrxR1 activity with subsequent ROS increase. We assessed Au cytotoxicity on GSCs with and without ionizing radiation using Alamar Blue and neutrosphere formation assays and ROS assay for quantitative analysis of ROS levels. We evaluated the molecular mechanisms associated with Au and IR-induced cell death in GSCs using western blotting analysis. Our findings suggest that resistance of GSCs to IR was accompanied with increased expression of TrxR1 and RAD51. On the other hand, Au alone significantly decreased GSC viability and neurosphere formation and sensitized GSCs to IR within the nanomolar range (significantly lower than the corresponding IC50s). Au alone and combined with IR increased ROS, while expression of both RAD51 and TrxR1 was decreased. Our study provides insights into repurposing the TrxR1 inhibitor, Au and its combination with RT as a novel therapeutic strategy to overcome GSC radioresistance and ultimately improve the dismal outcome of patients diagnosed with GBM.
STEM-09. EXPLORING THE ROLE OF TP53 IN REDOX REGULATION AND RESPONSE OF GLIOBLASTOMA STEM CELLS TO ROS-INDUCING AGENTS
Authors: Jamali Fatemeh , April Vincent , Sabri Siham , Abdulkarim Bassam 
Published: November 2023

Abstract
Glioblastoma, the most malignant primary tumor of the central nervous system in adults presents a major therapeutic challenge due to the presence of chemo-radioresistant glioblastoma stem cells (GSCs). These GSCs adapt the thioredoxin (Trx) and glutathione (GSH) antioxidant systems to counteract treatment-induced reactive oxygen species (ROS) and promote their survival. The tumor suppressor gene wild-type (wt)TP53 regulates the expression of pro-oxidant or antioxidant genes in response to chemoradiotherapy based on p53 DNA-binding activity in a reducing microenvironment. Given the importance of p53 as a redox-sensitive protein, we hypothesized that p53 might protect GSCs against ROS-inducing agents. Auranofin (Au), a FDA-approved gold(I)-containing compound inhibits thioredoxin reductase 1 (TrxR1), a key antioxidant protein. We investigated the effects of Au on different GSCs including wtp53 GSC line and its counterpart p53-knockdown. We assessed viability, neurosphere formation, ROS levels and expression of p53 and TrXR1 to evaluate the cytotoxicity of Au, alone and in combination with L-buthionine sulfoximine (L-BSO), a GSH-depleting agent. We conducted TCGA analysis to explore the correlation between TrxR1 and p53. Our findings revealed a positive significant correlation between p53 and TrxR1 expression, consistent with lower levels of TrxR1 in p53-knockdown GSCs compared to their wt-p53 counterparts. P53-knockdown GSCs displayed a higher basal level of ROS, which further increased upon treatment with Au. P53-knockdown significantly increased the sensitivity of cells to Au, with pronounced effects for Au/L-BSO combination. Our findings reveal that expression levels of wtp53 affect the role of p53 in TrxR1-redox regulation and sensitivity to ROS-inducing agents in GSCs.
STEM-11. A GLIOBLASTOMA SINGLE-CELL META-ATLAS IDENTIFIES NOVEL NEUROVASCULAR PROGENITOR IN TUMORS
Authors: Fazzari Elisa , Azizad Daria , Li Matthew , Ge Weihong , Bayley Nicholas , Tse Christopher , Tum Andrew , Raleigh David , Patel Kunal , Crouch Elizabeth , Nathanson David , Bhaduri Aparna 
Published: November 2023

Abstract
Glioblastomas (GBM) are defined by cell type heterogeneity that underlies treatment resistance and brain invasion. Recent studies have identified reactivation of neurodevelopmental cells and gene expression programs in GBM. Here, we leverage a neurodevelopmental perspective to identify novel gene signatures in GBM. To do so, we assembled a glioblastoma meta-atlas comprised of 73,376 single-cell transcriptomes from 7 published studies. With these data, we developed a novel module generation strategy to mitigate batch effects, enabled analysis of signatures in each tumors, and emphasized modules observed across multiple tumors. Using this approach, we validated known tumor cell types and axes of variation, and also identified novel stemness programs that were uniquely expressed across distinct progenitor populations. Within progenitor subtypes, we identified a neurovascular progenitor (NVP) of cells expressing a mixed vascular signature including genes characteristic of mural and endothelial identity as well as transcriptional programs reminiscent of neural stem cells. Although tumor associated or glioma stem cell derived vasculature has been described as important for tumor formation and progression, the NVP appears to be stem-like. To our knowledge, this population has not been described in GBM. We validated the existence of this NVP with immunofluorescence and fluorescent activated cell sorting from patient tumors followed by single-cell RNA-sequencing. Using a novel organoid transplantation model, we employed single-cell lineage barcoding to identify the progeny of patient-derived NVP cells, determining that they result in various cell types with diverse morphologies. Exploration of data from more traditional model systems including gliomaspheres and mouse GBM models indicate preservation of this NVP identity across systems. We hypothesize that NVP cells may play important roles in tumor plasticity, and thus may be a valuable therapeutic target to explore.
STEM-18. HYPOXIA-REGULATED EXPRESSION OF CD44 AND OSTEOPONTIN CAN CHANGE THE PHENOTYPE OF GLIOMA STEM-LIKE CELLS FROM HIGHLY INVASIVE TO LESS INVASIVE/PROLIFERATIVE TUMORS IN GLIOBLASTOMA
Authors: Nishikawa Masahiro , Inoue Akihiro , Ohnishi Takanori , Ozaki Saya , Kanemura Yonehiro , Suehiro Satoshi , Kohno Shohei , Ohue Shiro , Shigekawa Seiji , Watanabe Hideaki , Kunieda Takeharu 
Published: November 2023

Abstract

BACKGROUND
The poor prognosis of glioblastoma multiforme (GBM) is primarily due to highly invasive and highly migratory glioma stem-like cells(GSCs) in tumors. Upon GBM recurrence or progression, the highly invasive phenotype of GSCs changes to a less-motile, proliferative phenotype, thus generating tumor mass. Elucidating the molecular mechanism underlying this phenotypic transition could lead to the identification of effective molecular targets for treating GBM.

METHODS
We examined the effects of hypoxia (1% O2: severe or 5% O2: moderate) on the expression and functions of hypoxia-inducible factor(HIF), CD44 and osteopontin (OPN) to clarify the role of these molecules in GBM tumor invasion and proliferation. We also investigated the anti-tumor effects of CD44 knockdown in vitro and in vivo using a GSC-transplantation mouse model.

RESULTS
Severe Hypoxia upregulates CD44 expression via activation of HIF-1α, inducing GSCs to assume a highly invasive phenotype. In contrast, moderate hypoxia upregulates OPN expression via activation of HIF-2α. OPN inhibits CD44-promoted GSC migration and invasion and stimulates GSC proliferation, resulting in GSCs assuming a less-invasive, highly proliferative phenotype. CD44 knockdown significantly inhibited GSC migration and invasion both in vitro and in vivo, and the mice survived significantly longer than control mice.

CONCLUSION
The highly invasive phenotype of GSCs can be reversed by switching from severe to moderate hypoxia, leading to less-invasive and proliferative tumors. CD44 and OPN play a central role in regulating GSC invasion and proliferation by inducing a phenotypic transition, suggesting that these molecules could be effective targets for treating GBM.
STEM-23. TARGETING SOX2 IN GLIOBLASTOMA CELLS REVEALS HETEROGENEITY IN SOX2 DEPENDENCY
Authors: Dalmo Erika , Rosén Gabriela , Niklasson Mia , Bergström Tobias , Miletic Hrvoje , Lindskog Cecilia , Forsberg-Nilsson Karin , Nelander Sven , Uhrbom Lene , Swartling Fredrik , Westermark Bengt 
Published: November 2023

Abstract
The malignant primary brain tumor glioblastoma (GBM) has a dismal prognosis and current treatment options are insufficient to cure patients. The stem cell transcription factor SOX2 has been indicated as vital for GBM stem cell maintenance in vitro and GBM tumor formation in vivo, rendering it a putative therapeutic target for GBM. However, a few studies, including previous work from our lab, suggest a dichotomy in SOX2 dependence between different patients. To elucidate whether SOX2 independent GBMs exist and if so, how they are distinguished, we have investigated how altered SOX2 expression affects a panel of primary human GBM lines cultured under stem cell conditions. We found that elevated SOX2 expression inhibited proliferation in a dose-dependent manner in three out of four GBM cell lines. Global gene expression analysis showed that cells representing proliferation-inhibited and refractory cell lines end up on different ends of the developmental- to injury response GBM stem cell axis, were resistance to SOX2 overexpression was connected to an injury response expression profile. CRISPR/Cas9 mediated SOX2 knockout revealed a SOX2 independence in the refractory cell line, where cells lacking SOX2 could be propagated both in vitro and in vivo, implicating SOX2 as a non-essential gene for injury response-driven GBM stem cells. In current work, SOX2-dependent cell lines are engineered to express inducible exogenous SOX2 with concomitant endogenous SOX2 knockout, providing a system where SOX2 can be turned off at any time point. This system will be used in further studies elucidating the nature of SOX2 dependence and independence in GBM stem cells.
STEM-24. WDR5 REPRESENTS A THERAPEUTICALLY EXPLOITABLE TARGET FOR CANCER STEM CELLS IN GLIOBLASTOMA
Authors: Mitchell Kelly , Sprowls Samuel , Shakya Sajina , Arora Sonali , Silver Daniel , Goins Christopher , Wallace Lisa , Roversi Gustavo , Schafer Rachel , Kay Kristen , Miller Tyler , Lauko Adam , Bassett John , Kashyap Anjali , D'Amato Kass J , Mulkearns-Hubert Erin , Johnson Sadie , Alvarado Joseph , Rich Jeremy , Paddison Patrick , Patel Anoop , Stauffer Shaun , Hubert Christopher , Lathia Justin 
Published: November 2023

Abstract
Glioblastomas (GBMs) are heterogeneous, treatment-resistant tumors that are driven by populations of cancer stem cells (CSCs). In this study, we perform an epigenetic-focused functional genomics screen in GBM organoids and identify WDR5 as an essential epigenetic regulator in the SOX2-enriched, therapy resistant cancer stem cell niche. Despite their importance for tumor growth, few molecular mechanisms critical for CSC population maintenance have been exploited for therapeutic development. We developed a spatially resolved loss-of-function screen in GBM patient-derived organoids to identify essential epigenetic regulators in the SOX2-enriched, therapy resistant niche. Our niche-specific screens identified WDR5, an H3K4 histone methyltransferase responsible for activating specific gene expression, as indispensable for GBM CSC growth and survival. In GBM CSC models, WDR5 inhibitors blocked WRAD complex assembly and reduced H3K4 trimethylation and expression of genes involved in CSC-relevant oncogenic pathways. H3K4me3 peaks lost with WDR5 inhibitor treatment occurred disproportionally on POU transcription factor motifs, required for stem cell maintenance and including the POU5F1(OCT4)::SOX2 motif. We incorporated a SOX2/OCT4 motif driven GFP reporter system into our CSC cell models and found that WDR5 inhibitor treatment resulted in dose-dependent silencing of stem cell reporter activity. Further, WDR5 inhibitor treatment altered the stem cell state, disrupting CSC in vitro growth and self-renewal as well as in vivo tumor growth. Our results unveiled the role of WDR5 in maintaining the CSC state in GBM and provide a rationale for therapeutic development of WDR5 inhibitors for GBM and other advanced cancers. This conceptual and experimental framework can be applied to many cancers, and can unmask unique microenvironmental biology and rationally designed combination therapies.
CCRG-06. PP2A DEFICIENCY INDUCES CELLULAR SENESCENCE AND SENSITIZES P53 MUTANT TUMORS TO SENOLYTIC THERAPY
Authors: Mondal Isha , Das Oishika , Lu Rongze Olivia , Ho Winson 
Published: November 2023

Abstract
Loss of p53 can promote tumor progression by preventing induction of senescence, a critical tumor-suppressive mechanism that limits tumor proliferation. Promotion of senescence in a p53-independent manner can be a novel strategy to overcome treatment resistance in p53-mutant brain tumors. Protein-Phosphatase-2A (PP2A), a ubiquitous serine/threonine phosphatase, regulates various cellular processes including cell-cycle progression. We hypothesize that PP2A-deficiency can induce tumor senescence independent of p53-mutational-status and sensitize tumors to senolytic therapy. CRISPR-KO of PP2A was generated in multiple p53-mutant tumor cell lines: D425 (human medulloblastoma), SB28 and GL261 (murine glioma). Hallmarks of senescence such as b-galactosidase, p21, and p16 were assessed via flow cytometry, RT-PCR and Western-Blot. Secretion of senescence-associated secretory phenotype (SASP), such as IL8, was assessed through ELISA. b-galactosidase, p21, p16 and IL8 were dramatically increased in PP2A-KO compared to WT at baseline. The effect was further enhanced when combined with radiation therapy (RT), a known inducer of senescence, demonstrating PP2A-deficiency synergizes with RT and significantly increases cellular senescence. Expression of CD1d, a MHC1-like molecule associated with senescence and required for invariant NKT cell-activation (iNKT), was dramatically increased in PP2A-KO in comparison to WT via flow-cytometry. In-vitro, sensitivity to WT and PP2A-KO cells to senolytic treatments, such as ABT-737 and iNKT-cell therapy, was tested using an XCelligence-assay system and flow-cytometry-based cytotoxicity assay. PP2A-deficient cells were sensitized to ABT-737, a BCL-xL inhibitor that preferentially targets and kills senescent cells. Co-culture revealed increased cytotoxicity of iNKT-cells against PP2A-deficient tumors compared to WT. In vivo, D425 WT or PP2A-KO cells were injected intracranially into nude NU/J mice, radiated 2 days post-injection, and monitored till endpoint. At baseline, PP2A-KO mice survived longer than WT, and those with PP2A-KO and RT survived the longest. In conclusion, we report that PP2A-deficiency in tumor cells can induce p53-independent senescence and sensitize brain tumors to senolytic therapy.
CSIG-03. SHH PATHWAY ACTIVATION IN DEDIFFERENTIATION DURING TUMOUR PROGRESSION IN MPNST
Authors: Yakubov Rebeca , Bunda Severa , Zadeh Gelareh 
Published: November 2023

Abstract

BACKGROUND
Malignant peripheral nerve sheath tumours (MPNST) are highly aggressive sarcomas with little progress on outcomes and treatment strategies. Previous work conducted in our lab used unsupervised analyses of methylome and transcriptome profiles of 108 peripheral nerve sheath tumours to uncover two subgroups of MPNSTs that predict progression-free survival, MPNST-G1 (characterized by SHH pathway activation) and MPNST-G2 (characterized by WNT/ß-catenin/CCND1 pathway activation). Further, single nuclear RNA-sequencing revealed that MPNST-G1 and MPNST-G2 cells resemble neural crest-like and Schwann cell precursor-like cells, respectively.

PURPOSE & HYPOTHESIS
To examine the expression of transcription factors (TWIST1, SOX9, SNAI2, OTX2, PAX3, and PAX6) known to play canonical roles in the early neural crest cell specification in MPNST-G1 cells. We speculate that MPNST-G1 cells will display overexpression of these transcription factors compared to MPNST-G2 cells and that Sonidegib (SMO inhibitor) will revert dedifferentiation by decreasing activation of the SHH pathway.

METHODS
Dedifferentiation transcription factor expression and the effects of SMO activation and inhibition in MPNST-G1 and MPNST-G2 cells were analyzed using RT-PCR and western blotting. Alamar blue and Trypan blue assays were used to determine the effect of SMO inhibition on proliferation.

RESULTS
Compared to MPNST-G2 cells, MPNST-G1 cells displayed elevated expression of dedifferentiation transcription factors, SMO inhibition was able to reverse these effects. Conversely SMO activation induced the expression of these factors and induced an increase in proliferation.

CONCLUSIONS
The SHH pathway activation promotes the expression of important transcription factors in dedifferentiation. This finding provides insights into the transformation process of MPNST and novel therapeutic options for these lethal cancers.
CSIG-04. INTEGRATED MOLECULAR AND FUNCTIONAL CHARACTERIZATION OF THE INTRINSIC APOPTOTIC MACHINERY IDENTIFIES A DIAGNOSTICALLY INFORMED THERAPEUTIC APPROACH FOR MALIGNANT GLIOMA
Authors: Fernandez Elizabeth , Mai Wilson , Song Kai , Bayley Nicholas , Kim Jiyoon , Zhu Henan , Liau Linda , Li Gang , Yong William , Souers Andrew , Li Jingyi Jessica , Graeber Thomas , Cloughesy Timothy , Nathanson David 
Published: November 2023

Abstract
Molecular profiling often fails to predict therapeutic outcomes in cancer. This failure is, in part, due to myriad of genetic alterations and the plasticity of cancer signaling networks. Functional profiling, which ascertains signaling dynamics, has emerged as an alternative method to anticipate drug responses. Here we performed combined molecular and functional characterization (via BH3 profiling) of the intrinsic apoptotic machinery in glioma patient samples and derivative models. We identified that standard of care treatment rewires the apoptotic machinery in a genotype specific manner, revealing targetable vulnerabilities in gliomas containing specific molecular features (e.g., TP53 WT). However, integration of BH3 profiling uncovered that high mitochondria priming was also required to induce tumor apoptosis. Accordingly, a composite molecular and functional signature best predicted responses of diverse intracranial glioma models to standard of care combined with a new clinical drug targeting the intrinsic apoptotic machinery. This work demonstrates how complementary functional and molecular data can robustly predict therapy-induced cell death.