bluuebunny/crossref_metadata_2025_split huggingface dataset:
DDRE-02. SMOOTHENED-ACTIVATING LIPIDS DRIVE RESISTANCE TO CDK4/6 INHIBITION IN HEDGEHOG-ASSOCIATED MEDULLOBLASTOMA
Authors: Daggubati Vikas , Hochstelter Jordan , Bommireddy Ani , Choudhury Abrar , Krup Alexis , Kaur Pervinder , Tong Pakteema , Li Amy , Xu Libin , Reiter Jeremy , Raleigh David 
Published: March 2021

Abstract

BACKGROUND
Medulloblastoma is an aggressive pediatric brain tumor that is associated with misactivation of the Hedgehog (HH) pathway. Our lab has shown that CDK6, a critical activator of the cell cycle, is a direct transcriptional target of oncogenic HH signaling, and that inhibiting CDK6 blocks the growth of HH-associated medulloblastoma in mice. A clinical trial exploring the efficacy of CDK6 inhibition in medulloblastoma patients is underway, but prior attempts to target the HH pathway in medulloblastoma have been encumbered by resistance to molecular monotherapy. Thus, we sought to identify mechanisms of resistance to CDK6 inhibition in HH-associated medulloblastoma.

METHODS
We performed orthogonal CRISPR and CRISPR interference screens in HH-associated medulloblastoma cells treated with pharmacologic inhibitors of CDK6 in vitro, and RNA-sequencing of HH-associated medulloblastomas with genetic deletion of CDK6 in vivo. Mechanistic and functional validation of resistance pathways was performed using CRISPR interference, immunoblotting, immunofluorescence, genetics, and pharmacology. Lipid quantification was carried out by ultra-high performance liquid chromatography-tandem mass spectrometry.

RESULTS
Our results reveal that decreased ribosomal protein expression underlies resistance to CDK6 inhibition in HH-associated medulloblastoma, leading to endoplasmic reticular (ER) stress and activation of the unfolded protein response (UPR). We show that ER stress and the UPR increase the activity of enzymes producing Smoothened-activating sterol lipids that sustain oncogenic HH signaling in medulloblastoma despite CDK6 inhibition. These discoveries suggest that combination molecular therapy against CDK6 and HSD11ß2, an enzyme producing Smoothened-activating lipids, may be an effective treatment for HH-associated medulloblastoma. In support of this hypothesis, we demonstrate that concurrent genetic deletion or pharmacological inhibition of CDK6 and HSD11ß2 additively blocks the growth of multiple models of HH-associated medulloblastoma in mice.

CONCLUSIONS
Smoothened-activating lipid biosynthesis underlies resistance to CDK6 inhibition in HH-associated medulloblastoma, revealing a novel combination therapy to treat the most common malignant brain tumor in children.
DDRE-04. THE COMBINED TREATMENT OF L-ASPARAGINASE AND 6-DIAZO-5-OXO-L-NORLEUCINE INHIBIT THE PROLIFERATION OF TEMOZOLOMIDE-SENSITIVE OR RESISTANT GLIOBLASTOMA CELLS
Authors: Ohba Shigeo , Hirose Yuichi 
Published: March 2021

Abstract
Glioblastoma is one of the aggressive brain tumors with a 5-year survival rate of &lt; 10%. The standard treatment is maximal safe resection, followed by radiation therapy and temozolomide (TMZ). Clinically, the resistance to TMZ is a big problem. Cancer cells have been revealed to show different metabolism from normal cells. The object of this study is to evaluate whether cancer metabolism, especially asparagine, could be a new target of treatment in primary and recurrent glioblastoma. Glioblastoma cells (U251 and U87) were treated with L-asparaginase and/or 6-diazo-5-oxo-L-norleucine (DON). L-asparaginase converts asparagine into aspartate and depletes asparagine. DON is a glutamine analog that inhibits several glutamine-utilizing enzymes, including asparagine synthetase. L-asparaginase or DON suppressed the proliferation of U251, and U87 cells in a dose-dependent manner. Combined treatment with these drugs had a synergistic antiproliferative effect in these cell lines. The effect was counteracted by exogenous asparagine. The combined treatment induced greater apoptosis and autophagy than did single-drug treatment. Several clones of TMZ-resistant U251 were obtained after long treatment of TMZ to U251. The expression of MSH6, one of the mismatch repair proteins, was suppressed in these resistant clones. The synergistic effect of L-asparaginase and DON was detected in these U251-derived TMZ-resistant clones. These results suggest that the combination of L-asparaginase and DON could be a new therapeutic option for patients with primary and recurrent glioblastoma.
DDRE-07. FATTY ACID SYNTHESIS IS REQUIRED FOR BREAST CANCER BRAIN METASTASIS
Authors: Ferraro Gino , Ali Ahmed , Luengo Alba , Kodack David , Deik Amy , Abbott Keene , Bezwada Divya , Blanc Landry , Prideaux Brendan , Jin Xin , Possada Jessica , Chen Jiang , Chin Christopher , Amoozgar Zohreh , Ferreira Raphael , Chen Ivy , Naxerova Kamila , Ng Christopher , Westermark Anna , Duquette Mark , Roberge Sylvie , Lyssiotis Costas , Duda Dan , Golub Todd , Cantley Lewis , Asara John , Davidson Shawn , Fukumura Dai , Dartois Véronique , Clish Clary , Heiden Matthew Vander , Jain Rakesh 
Published: March 2021

Abstract
Brain metastases are refractory to therapies that otherwise control systemic disease in patients with human epidermal growth factor receptor 2 (HER2+) breast cancer, and the unique brain microenvironment contributes to this therapy resistance. Nutrient availability can vary across tissues, therefore metabolic adaptations required for breast cancer growth in the brain microenvironment may also introduce liabilities that can be exploited for therapy. Here, we assessed how metabolism differs between breast tumors growing in the brain versus extracranial sites and found that fatty acid synthesis is elevated in breast tumors growing in the brain. We determine that this phenotype is an adaptation to decreased lipid availability in the brain relative to other tissues, which results in a site-specific dependency on fatty acid synthesis for breast tumors growing at this site. Genetic or pharmacological inhibition of fatty acid synthase (FASN) reduces HER2+ breast tumor growth in the brain, demonstrating that differences in nutrient availability across metastatic sites can result in targetable metabolic dependencies.
DDRE-10. METABOLIC TARGETING OF HUMAN GLIOBLASTOMA USING 5-AMINOLEVULINIC ACID (ALA)-MEDIATED SONODYNAMIC THERAPY: A FIRST-IN-HUMAN STUDY
Authors: Marcus Stuart , Sanai Nader 
Published: March 2021

Abstract
Heme biosynthesis is altered in glioblastoma (GBM). Systemic dosing with ALA, the first committed molecule in the heme pathway, results in accumulation of the fluorescent intermediate, protoporphyrin IX (PpIX) only within tumor tissue (Gleolan label, 2019). PpIX is a photosensitizer that is effective in photodynamic therapy (PDT); in recurrent GBM patients, the safety and feasibility of ALA PDT has been demonstrated (Johansson A, et al. Lasers Surg Med 2013;45:225), although the practicality of this strategy in clinical care remains uncertain. Importantly, preclinical models of GBM show that PpIX is also a sonosensitizer and, in combination with transcranial MRI-guided focused ultrasound (MRgFUS), leads to non-ablative cytotoxic effects in vivo (Jeong EJ et al, Ultrasound in Medicine and Biology 2013:38;2143, Suehiro S et al, J Neurosurg 2018: 1377, Wu et al Nature Sci Reports 2019: 9;10465). The Ivy Brain Tumor Center is conducting a first-in-human study of 5-ALA sonodynamic therapy (SDT) for recurrent GBM (NCT 04559685). In this Phase 0/1 clinical trial, nontherapeutic, single-treatment SDT is administered prior to planned tumor resection. A Dose-Escalation Arm varies the power/energy of the MRgFUS while using a fixed time-interval from exposure to surgery. A subsequent Time-Escalation Arm varies the interval between MRgFUS and surgical resection, but fixes the power/energy of the delivered ultrasound. In both Arms, patient tumor tissue is assessed for sonodynamic and pharmacodynamic effects. In each patient, half of the tumor volume is not targeted with SDT and serves as an internal control. This first-in-human study will demonstrate the safety and feasibility of ALA sonodynamic therapy in GBM and may provide the first-ever biological evidence of sonosensitization in a brain tumor patient. If successful, this Phase 0 trial will introduce a new, metabolically-driven, GBM treatment modality that may be applicable to any brain tumor that selectively accumulates PpIX after ALA administration.
DDRE-17. A PHASE I CLINICAL TRIAL OF DOSE-ESCALATED METABOLIC THERAPY COMBINED WITH CONCOMITANT RADIATION THERAPY IN HIGH-GRADE GLIOMA
Authors: Porper Keren , Shpatz Yael , Plotkin Luba , Pechthold Ronit Goldman , Talianski Alisa , Hemi Rina , Mardor Yael , Jan Elisheva , Genssin Hili , Symon Zvi , Yair Anikster , Zach Leor , Lawrence Yaacov R 
Published: March 2021

Abstract

BACKGROUND
Animal brain-tumor models have demonstrated a synergistic interaction between radiation therapy and a ketogenic diet (KD). Metformin has in-vitro anti-cancer activity, through AMPK activation and mTOR inhibition. We sought to assess the feasibility of combined radiation, KD and metformin in adults with high grade gliomas.

METHODS
A prospective single-institution phase I clinical trial of combined metabolic therapy and radiotherapy. Radiotherapy was either 60Gy over six weeks or 35Gy over two weeks for newly diagnosed and recurrent gliomas, respectively. The dietary intervention consisted of a KD supplemented with medium chain triglycerides (MCT). There were three cohorts 1) dietary intervention alone, 2) low-dose metformin combined with dietary intervention and 3) high-dose metformin combined with dietary intervention. Clinicaltrials.gov NCT02149459.

RESULTS
A total of 13 patients were accrued, median age 61 years, of whom 6 had newly diagnosed and 7 with recurrent disease. All completed radiation therapy; 5 patients stopped the metabolic intervention early. Metformin 850mg three-times daily was poorly tolerated. There were no grade 4 / 5 adverse events, and only one grade 3 event (nausea). The median level of ketones during the intervention was 0.5 mM. Ketone levels were associated with dietary factors (high fat, low carbohydrates, MCT intake), use of metformin and low insulin levels. Median progression free survival was 10 months for newly diagnosed disease and 4 months for recurrent disease.

CONCLUSIONS
The intervention was fairly well tolerated, however only moderate ketones levels were obtained. Metformin use and dietary intake were associated with higher serum ketone levels. The recommended phase II dose is the 8 weeks of a low-carbohydrate diet combined with 850mg metformin twice daily.
DDRE-18. THE MITOCHONDRIAL PYRUVATE CARRIER—A METABOLIC TARGET OF MALIGNANT GLIOMA
Authors: Tiburcio Patricia , Murnyak Balazs , Coffman Kimberly , Huang Eric 
Published: March 2021

Abstract
Metabolic reprogramming has been recognized as crucial to the survival and proliferation of cancer cells through the reduction of glucose oxidation (the Warburg effect) and diversion of pyruvate and glycolytic metabolites to fuel anabolic processes. The mitochondrial pyruvate carrier (MPC) protein complex, consisting of MPC1 and MPC2, has been identified as essential for pyruvate transport into mitochondria. In most human cancers, MPC1 is frequently deleted or downregulated and, therefore, the MPC activity is low. Restoration of MPC levels increases pyruvate oxidation and markedly inhibits tumor growth. Despite being tumor suppressive in general, the role of MPC in malignant glioma seems complex. We reported previously that unlike MPC1 in IDH-mutant glioma, MPC2 expression correlated with worsened survival. Interestingly, MPC2 homo-oligomers have been identified recently as an efficient autonomous pyruvate transporter, which can be inhibited by an insulin sensitizer rosiglitazone but not by the MPC heterotypic oligomer inhibitor UK-5099. In this study, we report that glioma cells show low MPC1 expression but much higher MPC2 expression. Analysis of glioma patient data revealed that the mean MPC2 expression increased in a grade-dependent fashion whereas the mean MPC1 expression remained essentially low, thereby resulting in an increased MPC2/MPC1 ratio in association with glioma progression. Importantly, we show that malignant glioma cells are extremely sensitive to the mitochondrion-specific, PPARγ-sparing insulin sensitizer mitoglitazone but not UK-5099 whereas MPC-proficient glial cells are highly responsive to the latter, indicating MPC2 as an alternative pyruvate transporter in glioma. Furthermore, the addition of glutamate fully rescues the growth arrest of Mpc1-/- murine glial cells, suggesting the involvement of cerebral cortex-specific microenvironment in glioma growth. We are employing newly developed RCAS/tva Mpc1fl/fl mouse models to test therapeutic targeting of Mpc2 in spontaneously developed glioma.
DDRE-25. INVESTIGATING MITOCHONDRIAL SLC25A TRANSPORTERS INVOLVED IN SUPPORTING BRAIN TUMOUR METABOLISM AND SURVIVAL UNDER HYPOXIC CONDITIONS
Authors: Eales Katherine , Finch Alina , Wykes Victoria , Watts Colin , Tennant Daniel 
Published: March 2021

Abstract
Advancements in prevention, detection and treatment over the last 40 years have significantly transformed cancer healthcare however there are a few cancers, such as brain tumours, which are consistently lagging behind. The most common adult brain tumour is glioma; a highly aggressive cancer that invades deep into the surrounding brain consequently making treatment challenging. The severe hypoxic nature of glioma adds further complications to therapeutic efficacy as hypoxia limits efficient drug delivery as well as increasing treatment resistance. Therapies that therefore target both the hypoxic tumour microenvironment and metabolic pathways that sustain growth have significant potential to improve patient prognosis. It is well known that cancer cells demonstrate an abnormal metabolism, resulting in an altered requirement for amino acids to aid uncontrolled proliferation. Furthermore, tumour metabolism can also be influenced by this hostile hypoxic microenvironment, leading to a more malignant phenotype. We are therefore interested in a family of mitochondrial transporters, SLC25A, which translocate numerous solutes across the mitochondrial membrane and are crucial for many metabolic reactions. TCGA analysis has shown that many of these amino acid carriers are upregulated in glioma. Remarkably however, around 23 of the 53 mammalian SLC25A members lack defined substrate selectivity and so we are interested in identifying which transporters are particularly important in the metabolic adaptation to hypoxia. Using CRISPR and siRNA technologies we have identified transporters that are functionally required to maintain cell proliferation of glioma cell lines and patient tumour cells. Furthermore, using stable isotope-enriched nutrients, we have identified novel means by which glioma cell metabolism can be perturbed by inhibition of these transporters. Characterising which SLC25A transporters are important for hypoxic tumour metabolism could therefore expose a way to exploit these hypoxic areas subsequently making them more vulnerable to treatment and thus impacting patient survival.
DDRE-26. THE IMMUNO-METABOLIC ENZYME FASN PREVENTS CANCER-CELL INTRINSIC TYPE I INTERFERON RESPONSES IN GLIOBLASTOMA
Authors: De Martino Mara , Daviaud Camille , Vanpouille-Box Claire 
Published: March 2021

Abstract
Glioblastoma (GBM) is a devastating primary brain cancer with a median survival of 11–15 months. Radiation therapy (RT), the standard of care for GBM, can generate type I interferon responses (IFN-I) to jumpstart antitumor immunity. However, these effects are sometimes mitigated by inhibitory mechanisms that are exacerbated by RT. RT can modify GBM metabolism to promote de novo lipogenesis via the fatty acid synthase (FASN). Because FASN was found to impair IFN-I in antiviral immunity, we hypothesize that FASN is preventing RT-induced IFN-I responses to promote GBM survival and evade immune recognition. We first defined RT-induced metabolic changes in the GL261 murine GBM model. We observed an increase in mitochondrial respiration, glycolysis and in lipid metabolism-related pathways in 10 gray (Gy) irradiated GL261 cells. Additionally, we found upregulation of FASN by western blot and lipid accumulation by BODIPY staining in 10 Gy-GL261 cells. RT-induced lipid accumulation was reverted when GL261 cells were incubated with a FASN inhibitor. Next, to ask whether FASN was impairing IFN-I, GL261 cells were engineered to express an inducible shRNA silencing FASN (GL261shFASN) or its non-silencing control (GL261shNS). As expected, irradiation of GL261shNS cells enhanced the secretion of IFN-beta and CXCL10. This effect was more pronounced when FASN was abrogated in GL261 independently from the presence of RT. Finally, GL261shNS and GL261shFASN cells were orthotopically implanted in mice and IFN-I signaling was blocked by anti-IFN-I receptor antibody (a-IFNAR). Mice bearing GL261shFASN tumors presented a median survival of 51 days vs. 35 days for GL261shNS tumors, a significant prolongation of mice survival that was completely abrogated with a-IFNAR treatment. Overall, our findings suggest that FASN-mediated lipogenesis prevents RT-induced cancer cell intrinsic IFN-I to promote GBM survival. Consequently, it is possible that FASN acts as an immuno-metabolic checkpoint capable to regulate the immune system upon metabolic cues generated by RT.
DDRE-34. TARGETING RESISTANCE IN MEDULLOBLASTOMA
Authors: Chang Simone , Meiman Evan , Telang Sucheta 
Published: March 2021

Abstract
Medulloblastoma is the most commonly diagnosed pediatric brain tumor. Although therapeutic advances have improved survival from this cancer, they result in devastating sequelae and, additionally, have proven inadequate in metastatic disease and recurrence where survival remains &lt;5%. Effective therapies are urgently needed to improve outcomes in medulloblastoma. Medulloblastoma development is driven by dysregulation of normal cerebellar proliferation. Mutations in the sonic hedgehog (Shh) pathway are found in ~30% of these tumors and responsible for their aggressive growth. The poor outcomes in Shh-driven medulloblastoma have prompted the evaluation of Shh-targeting agents in their treatment – with limited success likely attributable in part to the upregulation of alternate survival pathways (e.g. Ras/MAPK and HIF-1α). These alternate mechanisms stimulate glycolysis, in part by increasing the activity of the 6-phosphofructo-2-kinase/fructose-2,6 bisphosphatases (PFKFB1-4) to produce fructose-2,6-bisphosphate (F26BP), a potent activator of the rate-limiting glycolytic enzyme, 6-phosphofructo-1-kinase. In recent studies, we have determined that the PFKFB4 enzyme is highly expressed in patient-derived Shh medulloblastomas. We have found that hypoxia, through HIF-1α, strongly induced PFKFB4 expression in Shh-driven medulloblastoma cells and that silencing PFKFB4 suppressed F26BP, glycolysis and proliferation in normoxia and, more markedly, in hypoxia, indicating that PFKFB4 may be required for growth under hypoxia. We found that simultaneously silencing PFKFB4 and Shh pathway effectors significantly reduced cell survival and that co-targeting PFKFB4 (with a novel inhibitor) and Shh effectors synergistically decreased cell viability. In order to simulate Shh antagonist resistance, we have now subjected Shh medulloblastoma cells to prolonged Shh inhibitor exposure and found that these cells exhibit increased proliferation, glycolysis and PFKFB4. Studies are underway to delineate their metabolic alterations. Taken together, our data indicate that targeting PFKFB4 may be a valid therapeutic option in aggressive, treatment-resistant medulloblastoma and strongly support the further examination of PFKFB4 inhibitors in these tumors.
ETMM-05. LACTIC ACID FACILITATES GLIOBLASTOMA GROWTH THROUGH MODULATION OF THE EPIGENOME
Authors: Torrini Consuelo , Nguyen Trang , Shu Chang , Mela Angeliki , Humala Nelson , Mahajan Aayushi , Karpel-Massler Georg , Bruce Jeffrey , Canoll Peter , Siegelin Markus 
Published: March 2021

Abstract
Glioblastoma (GBM) is the most common primary malignant brain tumor with an unfavorable prognosis. While GBMs utilize glucose, there are other carbon sources at their disposal. Lactate accumulates to a significant amount in the infiltrative margin of GBMs. In the current study, we demonstrated that lactate rescued patient-derived xenograft (PDX) GBM cells from nutrient deprivation mediated cell death and inhibition of growth. Transcriptome analysis, ATAC-seq and CHIP-seq. showed that lactic acid exposure entertained a signature of cell cycle progression and oxidative phosphorylation (OXPHOS) /tricarboxylic acid (TCA)-cycle. LC/MS analysis demonstrated that U-13C-Lactate elicited substantial labeling of TCA-cycle metabolites, acetyl-CoA and histone protein acetyl-residues in PDX derived GBM cells. Given that acetyl-CoA is pivotal for histone acetylation we observed a dose-dependent elevation of histone marks (e.g. H3K27ac), which was rescued by genetic and pharmacological inhibition of lactic acid-uptake, ATP-citrate lyase, p300 histone-acetyl-transferase and OXPHOS, resulting in reversal of lactate mediated protection from cell death. CHIP-seq. analysis demonstrated that lactic acid facilitated enhanced binding of H3K27ac to gene promoters and cis-regulatory elements. Consistently, ATAC-seq. analysis highlighted enhanced accessibility of the chromatin by lactic acid. In a combined tracer experiment (U-13C-glucose and 3-C13-lactate), we made the fundamental observation that lactic acid carbons were predominantly labeling the TCA cycle metabolites over glucose, implying a critical role of lactic acid in GBMs. Finally, pharmacological blockage of the TCA-cycle, using a clinically validated drug, extended overall survival in an orthotopic PDX model in mice without induction of toxicity, implying a critical role of lactic acid in GBMs and establishing lactic acid metabolism as a novel drug target for GBM.