Noble Gas Research Articles

Enhancing Florida red tilapia aquaculture: biofloc optimization improves water quality, pathogen bacterial control, fish health, immune response, and organ histopathology across varied groundwater salinities.

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250L-1 water) were used to store FRT fry (average weight of 1.73 ± 0.01g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR.

Study of Adhesion Molecules in Diabetes Mellitus Type2 Iraqi Patients with Dyslipidemia

Background: Cell adhesion molecules are protein entities that are located on the cell surface. The vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) expression is related to type 2 diabetes mellitus (T2DM) with dyslipidemia. Objectives: To determine the levels of VCAM-1 and ICAM-1 in T2DM patients with dyslipidemia and to explore the relationship between VCAM-1 and ICAM-1 and the development of dyslipidemia in T2DM patients. Patients and methods: The study included 150 individuals with an age range of (35-55) years. Patients with diabetes for more than 5 years were excluded. Fifty healthy individuals constituted Group 1 (G1), fifty patients with T2DM constituted Group 2 (G2), and fifty T2DM patients with dyslipidemia constituted Group 3 (G3). Whole blood samples were drawn to measure HbA1c based on fluorescence immunoassay technology. The serum was separated to measure fasting blood glucose (FBG), triglycerides (TG), total cholesterol (TC), and high-density lipoproteins (HDL) by manual methods, while VCAM-1, and ICAM-1 were determined using the ELISA test. The study was conducted between November 2022 and April 2023 at the National Center for Diabetes Treatment and Research, Baghdad, Iraq. Results: Significantly higher levels of FSG and HbA1c were detected in G2 and G3 compared to G1, but non-significantly so when G3 was compared to G2. Significant higher levels of TG and TC levels were detected for G3 when compared to G1 and G2, but non-significantly so when G2 was compared to G1. HDL levels were significantly lower in G3 compared to G2 and G1, but non-significantly so when G2 was compared to G1. VCAM-1, and ICAM-1 were significantly higher in G2 compared to G1, and VCAM-1 level was significantly higher in G3 compared to G2. Non-significant differences in ICAM-1 levels were found between G3 and G2. Conclusion: VCAM-1 and ICAM-1 are potentially significant factors in the development of dyslipidemia in diabetes patients. They might serve as biomarkers to accurately predict the progression of cardiovascular disease.

Sublimation of volatiles from H2O:CO2 bulk ices in the context of comet 67P/Churyumov–Gerasimenko

Context. The ROSINA instrument on board the Rosetta spacecraft measured, among others, the outgassing of noble gases from comet 67P/Churyumov–Gerasimenko. The interpretation of this dataset and unravelling underlying desorption mechanisms requires detailed laboratory studies. Aims. We aim to improve our understanding of the desorption patterns, trapping, and fractionation of noble gases released from the H2O:CO2-dominated ice of comet 67P. Methods. In the laboratory, ice films of neon, argon, krypton, or xenon (Ne, Ar, Kr, and Xe) mixed in CO2:H2O were prepared at 15 K. Temperature-programmed desorption mass spectrometry is employed to analyse the desorption behaviour of the noble gases. Mass spectrometric ROSINA data of 67P were analysed to determine the fraction of argon associated with CO2 and H2O, respectively. Results. CO2 has a significant effect on noble gas desorption behaviour, resulting in the co-release of noble gases with CO2, decreasing the amount of noble gas trapped within water, shifting the pure phase noble gas peak desorption temperature to lower temperatures, and prolonging the trapping of neon. These effects are linked to competition for binding sites in the water ice and the formation of crystalline CO2. Desorption energies of the pure phase noble gas release were determined and found to be higher than those previously reported in the literature. Enhancement of the Ar/Kr and Ar/Xe ratios are at best 40% and not significantly influenced by the addition of CO2. Analysis of ROSINA mass spectrometric data shows that the fraction of argon associated with H2O is 0.53 ± 0.30, which cannot be explained by our laboratory results. Conclusions. Multicomponent ice mixtures affect the desorption behaviour of volatiles compared to simple binary mixtures and experiments on realistic cometary ice analogues are vital to understanding comet outgassing.

Constraining the evolutionary stages of a hypogene karst system by combining morphological, geochemical and geochronological data - the example of carbonate breccia-hosted Melnička Peštera

A combination of morphological observations, geochemical data from calcite minerals and geochronology by burial age dating and U-series is used to constrain the geological and geomorphological setting and the evolutionary stages of a hypogene karst system. This methodological suit is applied to Melnička Peštera, a horizontal cave developed in carbonate breccia overlying dolomite marble in Melnica locality (N. Macedonia), where hydrothermal karst development occurred in both dolomite and calcite marble. The passage morphology of the cave, having a reverse triangle, Laughöhle cross-sections, suggests development near the water table by slowly moving waters. Calcite crusts are found throughout the cave, and based on their relationship to passage morphology, appear to pre-date main horizontal passage formation. Their carbonate stable and clumped isotope and fluid inclusion noble gas compositions indicate cooling of the hydrothermal system with an increased contribution of shallower groundwater. U-series data suggests Early Pleistocene deposition of the calcite crusts. Water table notches and convectional features carved into breccia bedrock and calcite crusts point to subsequent development at and above the water table by condensation corrosion. The solutional aggressiveness near the water table was likely related to CO2, that previously degassed from the deeper parts of the system where calcite was depositing, and redissolved in the cooler, shallower waters. Due to poor connection with the surface, the cave air above the water table likely had high pCO2, that further helped to maintain aggressiveness of the groundwater at the water-air contact, and boosted condensation corrosion above it, preventing deposition of related secondary calcite minerals. The cave-hosting carbonate breccia deposited as an alluvial fan filling up a paleovalley cut into Upper Miocene sediments. Cosmogenic nuclide burial age dating of quartz fragments confirms Early Pliocene age for the breccia, and constrains the paleovalley incision to Late Miocene, likely related to base level lowering caused by the Messinian Salinity Crisis.

Annual Effective Dose Estimation from Radon Concentration in Commonly Consumed Bottled Water in Northcentral Nigeria

Radon (222Rn), the heaviest among the noble gas in the periodic table of element, is radioactive nuclide that is naturally available in rocks, soil and water. In this study, a total of ten (10) brands of commonly consumed commercial bottled water in northcentral Nigeria were collected and assigned for their radon concentration using liquid scintillation counter (LSC). The highest radon (222Rn) concentration of 0.073 Bq/l was recorded in C Way bottled water while Mr. V bottled water recorded the lowest 222Rn concentration value of 0.016 Bq/l. These values were below the parametric reference level of 11.1 Bq/l set by United State of America Environmental Protection Agency and lower than the permissible limit of 100 Bq/l by World Health Organization (WHO) and European Union. Computed total annual effective dose due to ingestion and inhalation of waterborne radon recorded the highest mean value of 0.187 μSv/y in C Way Bottled water and lowest value of 0.041 μSv/y in Mr. V bottled water. Mean total annual effective dose recorded for all the bottled water samples were found to be significantly lower than the safety limit of 0.1 mSv/y recommended by WHO. The likelihood of any radiation incidence among the public due to consumption of commercial bottled water is therefore negligible.

Geochemical Signature of Deep Fluids Triggering Earthquake Swarm in the Noto Peninsula, Central Japan

AbstractOn New Year's Day 2024, a magnitude 7.6 event struck the Noto Peninsula in central Japan. Prior to this event, an intense earthquake swarm had persisted beneath the northeastern peninsula for more than five years. Geophysical evidence provides insight into the upwelling of deep fluids from the uppermost mantle that triggers the seismic swarm activity. The noble gases and their isotopes have been used as geochemical indicators to determine the origin of the fluids associated with the swarms and their upwelling. Gas samples collected from boreholes around the seismic source region are characterized by anomalously high 3He/4He ratios (∼3.9 RAcor), indicating infiltration of mantle fluids from the subcrustal lithosphere. Using a steady‐state advection model, we calculated mantle helium fluxes of 1.1–2.4 × 10−15 mol cm−2 a−1, similar to those estimated for other representative fault zones, such as the San Andreas and North Anatolian faults.

Atomistic Insights into Carbon Dioxide Sequestration in Natural Gas Hydrates in the Presence of Mixture of Flue and Noble Gases

AbstractThe exchange of carbon dioxide with methane in natural gas hydrates (NGHs) is one of the sustainable approaches for the sequestration of carbon dioxide in NGHs. However, the formation of mixed CH4─CO2 hydrates during CH4─CO2 exchange in NGHs reduces the rate of CH4─CO2 exchange in NGHs. It is reported that molecular level insights into CH4─CO2 exchange in NGHs using quaternary‐gas systems of CH4, CO2, and a mixture of flue (H2S and N2) and noble (Ne, Ar, Kr, and Xe) gases in heterogeneous medium using molecular dynamics simulation techniques. The sequestration of gases other than CH4 in the new hydrate cages besides the interface is the highest in CO2:H2S:Ar (2:1:1) system among all the reported quaternary‐gas systems. The results show that Ar enhances CO2 sequestration in NGHs in the presence of H2S rather than N2. The hydrate growth occurs due to the formation of dual hydrate cages. Among the methane molecules released from the hydrate slab in a binary‐gas (CH4─CO2) system, > 60 % of the released methane molecules reform new cages beside the interface. On the other hand, only ≈ 50 % of the released methane molecules reform new hydrate cages besides the interface in CO2:H2S:Ar (2:1:1) system.

Influence of energy transfer processes on the rovibrational characteristics of CO2 in low-temperature conversion plasma with Ar and He admixture.

The influence of argon and helium on the rovibrational kinetics of carbon dioxide (CO2) and CO in low-temperature conversion plasma is investigated. With this objective, a combined experimental and computational study is conducted, applying quantum cascade laser infrared absorption spectroscopy to a pulsed DC CO2 glow discharge with varying noble gas admixture and modeling it with a two-term Boltzmann solver. Time-resolved rovibrational temperatures and dissociation fractions are presented, exhibiting an increase in rotational-vibrational non-equilibrium and an increasing CO2 conversion with argon (Ar) and helium (He) admixtures. Results are discussed in the context of energy transfer processes for collisions involving electrons, corroborated by electron-kinetic modeling, and heavy particle collisions. With noble gas addition, an increase in the electron number density, promoting excitation, and the high-energy tail of the electron energy distribution function are found. Penning ionization processes are proposed as an explanation for the increase in conversion, showing higher conversion for Ar due to the lower excitation thresholds and, therefore, larger state population. In the context of rovibrational kinetics, processes leading to the gain or loss of vibrational energy of CO2 are analyzed, pointing out subtle differences in, for example, relaxation rate coefficients between Ar and He. However, the cooling of the gas through conductive heat transfer is identified as the most important influence of the Ar and He admixture, as it keeps the relaxation rate for vibrational quenching low.

Differential enrichment mechanism of helium in the Jinqiu gas field of Sichuan Basin, China

Helium is extensively utilized in aerospace, healthcare, electronics, semiconductors, advanced science, and renewable energy sectors, playing a pivotal role in the advancement of human technology. Presently, helium is primarily extracted from natural gas as an associated resource. The cost of extraction decreases with an increase in the helium concentration within the gases. Therefore, understanding the mechanisms involved in helium generation, migration, and accumulation underground is vital. This article delves into the differential enrichment mechanism of helium in the Jinqiu gas field, situated in the Sichuan Basin of China, by analyzing the molecular and isotopic composition characteristics of the major gases and noble gases, employing gas dissolution and diffusion models. Compared with other Jurassic gas reservoirs in the Sichuan Basin, the Jinqiu gas field contains a significantly higher helium concentration, displaying unique enrichment patterns within its area. The majority of hydrocarbon gases originate from the local underlying Triassic Xujiahe Formation source rocks. Specifically, the western section of the Jinqiu field is primarily supplied by the higher maturity Xujiahe Formation source rocks located in the western Sichuan Basin. Notably, there is no significant contribution of mantle-derived volatile components in the Jinqiu field. Helium and argon are primarily radiogenic, whereas neon primarily originates from atmosphere. The good linear correlation between 4He and 20Ne suggests that their transfer is primarily facilitated through groundwater. The solubility calculation reveals that the helium exsolved from the in-situ pore water of the reservoir, due to stratigraphic uplift during the Himalayan movement, comprises only 0.04%–0.11% of the existing reserves. This suggests that gas desolvation plays a relatively minor role in helium enrichment in the Jinqiu field. Additionally, the calculation results of gas diffusion indicate that diffusion's contribution to helium enrichment in the Jinqiu gas field remains minimal. Finally, our analysis of methane reserve changes suggests that the combined effect of differential loss and dilution of hydrocarbon gases is the primary mechanism for helium's differential enrichment in the Jinqiu field. Notably, methane and carbon dioxide depletion may be a significant factor in helium enrichment within the crustal natural gas system.

Degassing of CO2 triggers large-scale loss of helium from magma oceans

The moon-forming impact caused widespread melting and vaporization of the proto-Earth, leading to the formation of a protolunar disk1,2. Volatile elements trapped in the inner parts of the disk condensed together with heavier elements into a global magma ocean3,4. By subsequent cooling and degassing, volatiles contributed to the formation of the Earth’s secondary atmosphere5. The thermodynamic conditions at the magma ocean-atmosphere interface profoundly impacted the degree of degassing that occurred. Today, our understanding of these conditions remains unclear. Here, we simulate the degassing of carbon and helium from a magma ocean with a bulk silicate Earth composition6 at presumed typical conditions for the early Earth5,7. We employ first-principles molecular dynamics calculations. We find that volatile loss is determined by pressure, temperature, and melt composition. Carbon and helium devolatilize more easily when both elements are present in the melt, leading to pronounced loss from the magma ocean. Our findings suggest that the early Earth atmosphere was carbon-rich, with a high fraction of helium and other noble gases, and thicker and hotter than previously thought. We evaluate the implications for Earth’s composition and thermal evolution, as well as other planets that may undergo similar processes with different chemistries.

3D‐Printed Porous Organic Cages for Gas Filtration: Fabrication and Flow Simulations

AbstractPorous organic cages (POCs) are a class of emerging porous materials with high porosity and selectivity for gas adsorption and separation. As a representative of first‐generation POCs, the cage molecule CC3, has huge potential for separating noble gases and volatile organic compounds (VOCs). 3D printing CC3 using direct ink writing (DIW) offers significant advantages to build complex structures. Through rational design, formulations that are both printable and functional are achieved. Optimised formulations have the elasto‐visco‐plastic behavior required while retaining the functional properties of the cages. The characterization of printed parts evidence that the CC3 structure and adsorption capacity are well preserved. BET surface areas vary with CC3 concentration and can reach up to ≈249 m2 g−1 for 70 wt% CC3. However, high CC3 content leads to a decrease in shrinkage, higher porosity, and low compressive strength ≈0.7 MPa. Computational fluid dynamics (CFD) is used to investigate the gas flow behavior through grid‐type structures with tailored geometric parameters. The results reveal that changing the offset distance and porosity manipulates the flow path, velocity distribution, and pressure drop. This work provides a pathway to design and fabricate structures with multi‐scale porosity that can be widely used for other functional materials and applications.

MDB-107. MINNELIDE, A PROMISING COMPOUND FOR THE TREATMENT OF HIGH-RISK MEDULLOBLASTOMA

Abstract Despite the overall good outcome of children with medulloblastoma (MB), a subset faces the challenge of highly aggressive metastatic tumors. The poor prognosis for these patients underscores the urgent need for advancing therapeutic approaches. Minnelide, an analog of the natural product triptolide, exhibits potent antitumor activity in preclinical and early clinical settings. Despite its efficacy and tolerable toxicity, Minnelide has not been assessed against MB. Using a bioinformatic dataset integrating cellular drug response and gene expression, we predicted sensitivity of Group 3 (G3) MB, characterized by a poor five-year survival, to triptolide/Minnelide. Subsequent experiments confirmed the ability of both triptolide and Minnelide to reduce the viability of G3 MB cells ex vivo. Transcriptomic analyses identified MYC signaling, a crucial driver of G3 MB, as a downstream target of these drugs. We validated the MYC dependency and demonstrated that triptolide affects both MYC transcription and protein stability. Notably, Minnelide acted in vivo on MYC, leading to reduced tumor growth and metastatic spread, resulting in improved survival in mouse and patient-derived G3 MB models. Furthermore, Minnelide enhanced the efficacy of adjuvant chemotherapy, suggesting its potential repurposing for treating MYC-driven G3 MB patients.

MDB-76. ONC201 INHIBITS THE CHARACTERISTICS OF CANCER STEM CELLS IN GROUP 3 MEDULLOBLASTOMA

Abstract BACKGROUND Medulloblastoma (MB), the most frequent childhood brain tumor, originates in the cerebellum. Despite treatment advances, recurrence affects 40%, with a mortality rate of 30%. Cancer stem cells drive tumor initiation, maintenance, and therapy resistance, in several tumors including MB (MBSC). In response to stress, stem cells activate mechanisms like the unfolded protein response (UPR) to maintain homeostasis and survive adverse conditions. The UPR restores endoplasmic reticulum balance, supporting cell function and survival. Recent studies have shown that the UPR plays an important role in tumorigenesis, however, its function in MBSC remains unknown. METHODS To understand the involvement of the UPR in stem cell maintenance, we have investigated the biological effects of its pharmacological inhibition on Group 3 (G3) MBSC. We selected three G3 MB cell lines (D283-Med, D341-Med and Med411), for in vitro studies. Cell line selection was based on their fidelity to the expected methylation class, corresponding to the subgroup of the parental tumors, and were grown in “stem-like” conditions as neurospheres. We evaluated drugs targeting the UPR stress program, identifying ONC201 as the most effective against MBSC. ONC201 is an imipridone compound that activates p53-independent apoptosis causing changes in gene expression similar to those caused by UPR. RESULTS Our findings revealed that ONC201 modulates protein synthesis via ATF4, a pivotal UPR molecule, with stronger induction observed in MB cells cultured under “stem-like” conditions. This ATF4 upregulation triggers the activation of pro-apoptotic programs. Additionaly, ONC201 was effective on reducing the stem-like features of MBSC, including self-renewal, stem cell markers expression, migration, and invasion potential. Notably, ONC201 demonstrates synergy with vincristine and methotrexate chemotherapy. CONCLUSIONS These results propose ONC201 as a promising agent for targeting G3 medulloblastoma by compromising the stem cell compartment. Further investigation is warranted to confirm its efficacy and potential clinical application.

MODL-06. USING HYDROGEL MODELS TO RECAPITULATE THE TUMOUR-IMMUNE MICROENVIRONMENT OF AGGRESSIVE GROUP 4 MEDULLOBLASTOMA TUMOURS

Abstract BACKGROUND Medulloblastoma is the most common malignant childhood brain-tumour, predominantly affecting children between the ages of one and nine. It is divided into four molecular subgroups amongst which, Group 3 (G3) and Group 4 (G4) subgroups have the worst prognosis. Subgroups possess distinct extracellular-matrix (ECM) and tumour immune microenvironments (TIME) directly influencing therapy-response and metastasis. Current models of medulloblastoma fail to precisely recreate the complex, subgroup-specific TIME and do not mimic intricate immune-tumour heterotypic signalling facilitating immune-evasion. Here we use a HyStem-hydrogel which forms a hyaluronan-rich environment mimicking the natural brain architecture. This overcomes several limitations of current MB models, allowing customisation of subgroup matching of ECM components, adjustable ECM-stiffness and co-culturing of immune cells. METHODS HyStem-hydrogels were co-assembled with ECM components (with/without laminin) and G4 medulloblastoma cell line CHLA-01-MED. Hydrogels were imaged every three-days using an EVOS M7000 system and assessed for cell-viability with PrestoBlue every seven days. Co-culture laminin-supplemented HyStem hydrogels were established with M1-like or M2-like resting/activated macrophages and their growth tracked in the same manner. On day twenty-eight, hydrogels were fixed and stained for markers of cellular proliferation (Ki-67), ECM (laminin, vitronectin) and macrophage markers. Media from hydrogel co-cultures was collected and ELISAs permofmed to assess cytokine production. RESULTS Hydrogels with/without laminin both remained viable and stable for 28 days. Laminin-supplemented hydrogels displayed a mixed laminar-nodular phenotype which mirrored the heterogenous nature of G4 patient-tumours. Co-culture of CHLA-01-MED cells with activated-macrophages led to cytokine production and altered growth patterns. CONCLUSION We show that HyStem hydrogels recapitulate biologically relevant behaviour of aggressive G4-MB tumours in vitro and represent a promising model for G4-tumours. Future research will involve inclusion of additional brain relevant cells/ECM components and comparisons to a fully customisable peptide-amphiphile hydrogel.

MDB-01. A POSITIVE FEEDBACK LOOP BETWEENLNC-HLX-2-7, HLX, AND MYC STRONGLY PROMOTES GROUP 3 MEDULLOBLASTOMA

Abstract Recent studies suggest that long non-coding RNAs (lncRNAs) contribute to medulloblastoma formation and progression. We have identified a lncRNA, lnc-HLX-2-7, as a potential therapeutic target in group 3 (G3) medulloblastomas. lnc-HLX-2-7 RNA specifically accumulates in the promoter region of HLX, its host gene, which activates HLX expression by recruiting multiple factors, including enhancer elements. RNA sequencing and chromatin immunoprecipitation reveal that HLX binds to and activates the promoters of several oncogenes, including TBX2, LIN9, HOXM1, and MYC. Intravenous treatment with cerium oxide nanoparticle–coated antisense oligonucleotides targeting lnc-HLX-2-7 (CNP-lnc-HLX-2-7) inhibits tumor growth by 40-50% in an intracranial medulloblastoma xenograft mouse model (p<0.01). Combining CNP-lnc-HLX-2-7 with standard-of-care cisplatin further inhibits tumor growth and significantly prolongs mouse survival compared with CNP-lnc-HLX-2-7 monotherapy (p<0.01). Thus, the lnc-HLX-2-7–HLX–MYC axis is important for regulating G3 medulloblastoma progression, providing a strong rationale for using lnc-HLX-2-7 as a therapeutic target for G3 MBs in children.

MDB-68. DISCOVERING DRUG SENSITIVITIES IN MEDULLOBLASTOMA USING PATIENT- AND PDX-DERIVED TUMOROIDS

Abstract BACKGROUND Medulloblastoma (MB) is one of the most common malignant pediatric brain tumor types and is subdivided into four major types: WNT, SHH, Group 3 and Group 4. Treatment, including resection, cranio-spinal radiotherapy, and chemotherapy, often leads to undesirable long-term side effects. MB prognosis depends on type, subtype, and genetic alterations, reflecting the high level of heterogeneity observed in these tumors and indicating that specific patient populations with particularly poor prognosis require alternative treatment approaches. Therefore, preclinical models are essential for recapitulating MB heterogeneity and developing subtype-specific treatments. METHODS Long-term in vitro MB tumoroid models were developed from patient and PDX tumors and molecularly characterized using DNA methylation and transcriptomic analyses. High-throughput single drug screening (225 compounds) and combination screening were performed to identify (subtype-specific) drug sensitivities. RESULTS Fifteen tumoroid lines were established from TP53-mutated SHH (n=6), Group 3 (G3) MYC-amplified (n=4) and non-amplified (n=5) patient (n=6) and PDX (n=9) tumors. DNA methylation analyses confirmed the maintenance of molecular identity in these tumoroids after long-term culture (>5 passages). Transcriptome analyses reveal a more proliferative, progenitor-like phenotype in these tumoroids compared to patient/PDX tumors. Hight-throughput drug screens identified both common and type-specific drug sensitivities within MB. Notably, drugs targeting CDK7, CDK12, CHECK1, BCL2L, and HDAC demonstrated efficacy in both G3 and TP53-mutated SHH-MB, while TOP1/2 and MDM2 inhibitors were specific for G3-MB. Currently, these drugs are being further investigated to select the most effective synergistic drug combinations for in vivo validation in PDX models. CONCLUSIONS Thus far, we have established already fifteen MB tumoroid models representing SHH-MB and G3-MB and identified several drug targets, including cell cycle kinases and HDACs. Tumoroids closely resemble patient tumors, based on methylome and transcriptome, enhancing their relevance for drug discovery applications in a high-throughput fashion and for prioritizing new treatment strategies for MB patients in clinical trials.

MDB-08. MYC AND TGFΒ PROMOTE GROUP 3 MEDULLOBLASTOMA TUMOR RESISTANCE THROUGH DEREGULATION OF POLYCOMB TARGETS

Abstract Medulloblastoma (MB) is one of the most prevalent malignant brain tumors in children, with tremendous cognitive and neuroendocrine disability among survivors. Group 3 (G3) MBs have poor overall survival at <50%, higher frequency of metastasis, and no targeted therapies. Amplification of MYC and activation of TGFβ signaling are frequent in G3MB. Remarkably, some tumors have no reported mutations, suggesting roles for epigenetic mechanisms in driving disease. We have generated new humanized models for G3MB by transforming neuroepithelial stem cells (NESC) derived from human induced pluripotent stem cells with TGFβ effectors alone and/or in combination with MYC, prioritizing combinations observed in patients. Excitingly, both MYC and TGFβ effectors drove tumor formation in vivo with the combination of TGFβ effectors and MYC leading to more aggressive tumors. Moreover, NESC-derived tumors clustered with human G3/G4MB samples, indicating our models recapitulates human disease. We next found that NESCs expressing MYC with either TGFβR1 or TGFβ1 showed resistance to clinical TGFβR1 inhibitors, compared to cells driven by either TGFβR1 or TGFβ1 alone. To decipher mechanisms of resistance, we integrated CUT&RUN to probe for MYC genomic localization and relevant histone PTMs with RNA-seq analysis and discovered a subset of genes upregulated in MYC and TGFβ-driven lines that are targets of the histone demethylase KDM2B and Polycomb Repressive Complex 2 (PRC2) member SUZ12. Moreover, we found that MYC is bound to regions normally regulated by PRC interactors. We postulate that chromatin remodeling via MYC and recruitment of other MYC-interacting cofactors to PRC targets culminates in transcriptional changes that lead to aggressive disease. Work from others suggests that PRC-mediated chromatin regulation is critical in many adult and pediatric brain tumors, underscoring its significance in MB. Our studies provide important insight on identifying new therapeutic avenues with a focus on the epigenetic landscape for patients with MYC and TGFβ driven G3MB.

MDB-93. A TRANSCRIPTOME-BASED APPROACH TO DRUG REPURPOSING FOR AGGRESSIVE GROUP 3 MEDULLOBLASTOMAS

Abstract BACKGROUND Medulloblastoma (MB) is the most common malignant brain tumor in children, representing 20% of pediatric brain tumors. International consensus has identified molecular subgroups: WNT, SHH, group 3 (G3), and group 4 (G4). Current treatments, guided by histologic tumor grade and stage, do not fully harness these subgroups, resulting in varying prognoses. G3MB particularly faces challenges with rapid recurrence and aggressive disease, necessitating focused intervention. METHODS We conducted differential expression analysis on MB patient datasets (GSE148389, GSE164677) to generate a G3MB gene expression signature. This gene expression signature was analyzed against the LINCS database, yielding candidate antineoplastic compounds. Candidates were filtered for blood-brain barrier permeability and FDA approval. Functional assays evaluated drug effects on cytotoxicity, clonogenicity, wound healing, cell cycle, and apoptosis in G3MB cell lines (HDMB03 and D425). RNA sequencing of treated cells identified differentially regulated pathways to infer mechanism, followed by in vitro validation. Mitochondrial function and membrane potential were measured by Seahorse and TMRM assays, respectively. RESULTS Eighty-one candidates passed filtering. The leading drug class identified was antidepressants. Based on MTT assays, the top four candidates were nortriptyline, simvastatin, fluoxetine, and sertraline. Nortriptyline (NT) emerged as the lead compound, with IC50 values of ~7uM (HDMB03) and ~11uM (D425). Amongst the four drugs, NT induced consistent anti-neoplastic effects on wound healing, colony formation, medullosphere generation, and apoptosis. Mechanistically, NT induced mitochondrial stress, escalated mitochondrial superoxide, and decreased mitochondrial membrane potential. CHRM3, a receptor antagonized by NT and upregulated in G3MB samples was downregulated by NT treatment. Western blotting confirmed the inhibition of CHRM3 downstream effectors. CONCLUSIONS Our pipeline identified cytotoxic compounds against G3MB, including NT, which we hypothesize induces mitochondrial stress via CHRM3 modulation. This approach offers repurposable FDA-approved candidates for high-risk G3MB, potentially reducing current treatment toxicity and improving outcomes.

PHAHST Potential: Modeling Sorption in a Dispersion-Dominated Environment.

PHAHST (potentials with high accuracy, high speed, and transferability) is a recently developed force field that utilizes exponential repulsion, multiple dispersion terms, explicit many-body polarization, and many-body van der Waals interactions. The result is a systematic approach to force field development that is computationally practical. Here, PHAHST is employed in the simulation for rare gas uptake of krypton and xenon in the metal-organic material, HKUST-1. This material has shown promise in use as an adsorptive separating agent and presents a challenge to model due to the presence of heterogeneous interaction sorption surfaces, which include pores with readily accessible, open-metal sites that compete with dispersion-dominated pores. Such environments are difficult to simulate with commonly used empirical force fields, such as the Lennard-Jones (LJ) potential, which perform better when electrostatics are dominant in determining the nature of sorption and alone are incapable of modeling interactions with open-metal sites. The effectiveness of PHAHST is compared to the LJ potential in a series of mixed Kr-Xe gas simulations. It has been demonstrated that PHAHST compares favorably with experimental results, and the LJ potential is inadequate. Overall, we establish that force fields with physically grounded repulsion/dispersion terms are required in order to accurately model sorption, as these interactions are an important component of the energy. Furthermore, it is shown that the simple mixing rules work nearly quantitatively for the true pair potentials, while they are not transferable for effective potentials like LJ.

Triptolide and its prodrug Minnelide target high-risk MYC-amplified medulloblastoma in preclinical models.

Most children with medulloblastoma (MB) achieve remission, but some face very aggressive metastatic tumors. Their dismal outcome highlights the critical need to advance therapeutic approaches that benefit such high-risk patients. Minnelide, a clinically relevant analog of the natural product triptolide, has oncostatic activity in both preclinical and early clinical settings. Despite its efficacy and tolerable toxicity, this compound has not been evaluated in MB. Utilizing a bioinformatic data set that integrates cellular drug response data with gene expression, we predicted that Group 3 (G3) MB, which has a poor 5-year survival, would be sensitive to triptolide/Minnelide. We subsequently showed that both triptolide and Minnelide attenuate the viability of G3 MB cells ex vivo. Transcriptomic analyses identified MYC signaling, a pathologically relevant driver of G3 MB, as a downstream target of this class of drugs. We validated this MYC dependency in G3 MB cells and showed that triptolide exerts its efficacy by reducing both MYC transcription and MYC protein stability. Importantly, Minnelide acted on MYC to reduce tumor growth and leptomeningeal spread, which resulted in improved survival of G3 MB animal models. Moreover, Minnelide improved the efficacy of adjuvant chemotherapy, further highlighting its potential for the treatment of MYC-driven G3 MB.