The Role of GABA Transaminase ABAT in Pediatric Brain Tumor Medulloblastoma Development and Spread

GABA 转氨酶 ABAT 在小儿脑肿瘤髓母细胞瘤发展和扩散中的作用

• 批准号: 10716956
• 负责人: ANAT ERDREICH-EPSTEIN
• 金额: $ 57.96万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10716956
• 关键词: 4-Aminobutyrate aminotransferase; ATAC-seq; Amino Acid Sequence; BARHL1 gene; Biological; Biological Assay; Blood - brain barrier anatomy; Brain; Cell Nucleus; Cells; Cerebellum; Cerebrospinal Fluid; Cessation of life; Characteristics; Child; Childhood Brain Neoplasm; Childhood Malignant Brain Tumor; Chromatin Structure; Cisplatin; Competence; Control Animal; Cytoplasmic Granules; Data; Development; Disease; Energy-Generating Resources; Enzymes; Epigenetic Process; Foundations; Gene Activation; Genetic Transcription; Goals; Growth; Histone Acetylation; Histone Deacetylase; Histone H3; Human; Immunoprecipitation; In Vitro; Leptomeninges; Lesion; Life; Lysine; Malignant Neoplasms; Maximum Tolerated Dose; Metabolic; Metabolism; Metastatic Neoplasm to the Leptomeninges; Mitochondria; Modification; Mus; Neoplasm Metastasis; Nervous System; Neurobiology; Neuroglia; Neurons; Neurosciences; Neurotransmitters; Nuclear; Nutrient; Oncogenes; Outcome; Paper; Pathogenesis; Patients; Pharmaceutical Preparations; Phenotype; Primary Neoplasm; Proliferating; Publishing; Receptor Activation; Reporting; Research; Role; Route; Shunt Device; Signal Transduction; Site; Spectrum Analysis; Therapeutic; Toxic effect; Transgenic Mice; Vincristine; Xenograft procedure; blood-brain barrier crossing; blood-brain barrier permeabilization; comparison control; gamma-Aminobutyric Acid; in vivo; induced pluripotent stem cell; inducible gene expression; inhibitor; knock-down; medulloblastoma; mortality; mouse model; neoplastic cell; nerve stem cell; neural; neurodevelopment; novel; novel therapeutic intervention; overexpression; protein H(3); radiation resistance; receptor; small molecule; standard of care; stem cell differentiation; therapeutic target; transcriptome; transcriptome sequencing; tumor; tumor microenvironment; tumorigenic

Medulloblastoma (MB), is the most common pediatric brain tumor originating in the GABA-rich cerebellum. 40% of MB patients present as both cerebellar and cerebral spinal fluid (CSF) leptomeningeal metastases which results in having dismal outcomes. The project’s long-term goal is to determine how MB become life-threatening leptomeningeal metastases by studying the tumor and brain microenvironment from a neurodevelopment and cancer neuroscience perspective. Although abnormal GABAergic receptor activation has been described in group 3 MB, no studies until ours recently had yet to elucidate the contribution of receptor-independent GABA metabolism to MB pathogenesis and metastasis. Overall, we were the first to identify GABA metabolic shunt enzyme GABA Transaminase (ABAT) expression is correlated with cerebellar development and is used by MB to survive in the cerebrospinal fluid microenvironment and promote leptomeningeal dissemination. Specifically, we show proliferative MB cells at the primary cerebellar site have low ABAT. However, a sub-population of ABAT positive MB cells at the primary cerebellar site display neuron-like characteristics (including metabolism) and are the seeds of MB metastasis. In addition to being a GABA metabolic enzyme, we determined that expression of ABAT induces epigenetic modification by significantly reducing histone acetylation at the 4th lysine residue of the histone H3 protein (H3K4ac) and significantly increase in histone deacetylase activity. Furthermore, ABAT expression fluctuates depending on metabolite changes in the tumor microenvironment, with nutrient-poor conditions upregulating ABAT expression. We found metastatic MB cells require ABAT to maintain viability in the metabolite-scarce CSF by using GABA through the GABA metabolic shunt as an energy source substitute, thereby facilitating leptomeningeal metastasis formation. Therefore, we hypothesize ABAT has a dual-biological role: lack of its expression during normal cerebellar development contributes to proliferation leading to group 3 medulloblastoma formation; While its overexpression after MB development results in tumor dormancy leading to survival benefit in disseminated cells in leptomeningeal metastasis. Utilizing foundations of neurobiology by using: a) human and mouse-derived neural stem cells, neurons and glial cells, b) unique strengths of patient-xenografts, c) BarTeL transgenic mice, d) novel small molecule ABAT inhibitor which crosses the blood-brain barrier, we will: 1st interrogate the role of ABAT in cerebellar neurodevelopment and Group 3 MB initiation, 2nd contribution of nuclear ABAT to transcription through histone acetylation modification in metastases, 3rd investigate ABAT as a potential therapeutic target for MB metastases. The current proposal will shed further light on understanding how metastatic MB cells develop and adapt to their neural niche opening avenues for novel therapeutic interventions for children that have this devastating disease.

髓母细胞瘤 (MB) 是最常见的儿童脑肿瘤，起源于富含 GABA 的小脑，占 MB 的 40%。 患者表现为小脑和脑脊液 (CSF) 软脑膜转移，导致预后不良 该项目的长期目标是确定 MB 如何成为危及生命的软脑膜转移瘤。 从神经发育和癌症神经科学的角度研究肿瘤和大脑微环境。 异常 GABA 受体激活已在第 3 MB 组中描述，直到我们最近还没有研究 阐明受体独立的 GABA 代谢对 MB 发病机制和转移的贡献。 我们首先发现 GABA 代谢分流酶 GABA 转氨酶 (ABAT) 的表达与 MB 利用其在脑脊液微环境中生存并促进小脑发育 具体来说，我们发现小脑原发部位的增殖性 MB 细胞 ABAT 较低。 然而，初级小脑部位的 ABAT 阳性 MB 细胞亚群表现出神经元样特征 （包括代谢）并且是MB转移的种子除了是GABA代谢酶之外，我们确定。 ABAT 的表达通过显着降低第 4 个赖氨酸的组蛋白乙酰化来诱导表观遗传修饰 组蛋白 H3 蛋白 (H3K4ac) 残基和组蛋白脱乙酰酶活性显着增加。此外，ABAT 在营养不良的情况下，表达会根据肿瘤微环境中代谢物的变化而波动 我们发现转移性 MB 细胞需要 ABAT 来维持代谢物稀缺的活力。 CSF通过使用GABA通过GABA代谢分流作为能源替代品，从而促进软脑膜 因此，我们认为ABAT具有双重​​生物学作用：正常情况下其表达缺乏。 小脑发育有助于增殖，导致第 3 组髓母细胞瘤形成； MB 发育后的过度表达导致肿瘤休眠，从而导致播散细胞的生存获益 利用神经生物学基础：a) 人类和小鼠来源的神经干细胞， 神经元和神经胶质细胞，b) 患者异种移植物的独特优势，c) BarTeL 转基因小鼠，d) 新型小分子 ABAT 穿过血脑屏障的抑制剂，我们将： 1st 探究 ABAT 在小脑神经发育中的作用 和第 3 组 MB 起始，核 ABAT 通过组蛋白乙酰化修饰对转录的第二贡献 转移，第三研究 ABAT 作为 MB 转移的潜在治疗靶点当前的提案将进一步阐明。 有助于了解转移性 MB 细胞如何发育并适应其神经生态位，为新的研究开辟了途径 对患有这种毁灭性疾病的儿童进行治疗干预。