The hypoxic niche in glioblastoma is maintained by myeloid produced creatine

项目总结/摘要 胶质母细胞瘤（GBM）是成人中最常见的脑肿瘤恶性肿瘤，其特征在于独特的 称为假栅栏状坏死的小凹。这些缺氧区域是该疾病的一个定义特征， 促进化学抗性、放射抗性，并最终驱动疾病进展。了解 这些区域的生成和维持对于了解如何有效治疗该疾病至关重要。 对人类GBM患者的多组学分析揭示，肌酸转运蛋白Slc6a8特异性地 由缺氧和坏死区域的肿瘤细胞表达。围绕这些区域的是肿瘤相关的 骨髓细胞（TAMCs），其是GBM中最丰富的浸润性免疫细胞。令人惊讶的是， 围绕低氧假栅栏区的细胞表达产生肌酸所必需的酶。 因此，我们假设TAMC来源的肌酸促进了假栅栏的产生， 在GBM中的坏死生态位，并且这种代谢串扰促进GBM适应性和治疗抗性。 先前的工作已经确定，缺氧假栅栏状龛含有胶质瘤干细胞（GSC）， 这是由这些区域内的缺氧应激产生的。此外，Slc6a8直接受 缺氧，表明肌酸摄取对GSC表型发挥作用。因此，本建议的第一个目的是 研究肌酸转运如何影响GBM的人类和小鼠模型中的GSC表型。在这 目的，我们还将利用可诱导的GBM模型，概括人类GBM的遗传和病理特征， GBM以确定Slc6a8是否是肿瘤中缺氧假栅栏状小生境形成所必需的。 我们的初步数据表明，从患有GBM的小鼠和人类中分离的TAMCs是熟练的。 肌酸的生产者。此外，我们发现这种代谢表型是肿瘤特有的， 微环境（TME），并诱导细胞外乳酸。因此，本提案的第二个目标将 检查TAMCs如何消除肌酸生物合成控制小鼠肿瘤生长和进展 GBM模型这一目标也将确定乳酸如何诱导TAMCs的肌酸生物合成表型 在GBM。 本建议的第三个目的是检查临床相关的肌酸转运抑制剂是否影响 GBM增长。我们将测试这种抑制剂如何在化疗和放疗的背景下起作用，以确定如何 肌酸摄取影响GBM复发。为了从这项工作中建立可翻译的价值，我们将产生 肿瘤样品和来自患者的患者来源的异种移植物，筛选它们的肌酸代谢酶的表达， 基因，然后评估敏感性肌酸代谢抑制治疗。这一目标的结果将确定， 阻断TAMC与肿瘤的代谢通讯是GBM治疗的可行策略。

PROJECT SUMMARY/ABSTRACT Glioblastoma (GBM) is the most common brain tumor malignancy in adults that is characterized by unique niches termed pseudo-palisading necrosis. These hypoxic regions are a defining feature of the disease which promote chemoresistance, radioresistance, and ultimately drive disease progression. Understanding the generation and sustainment of these regions is critical to understanding how to effectively treat the disease. Multi-omics analysis of human GBM patients reveals that the creatine transporter, Slc6a8 is specifically expressed by tumor cells in hypoxic and necrotic regions. Surrounding these regions are tumor-associated myeloid cells (TAMCs), which are the most abundant infiltrating immune cell in GBM. Surprisingly, the TAMCs that surround the hypoxic pseudo-palisading regions express the enzymes necessary to produce creatine. Therefore, we hypothesize that TAMC-derived creatine promotes the generation of the pseudo-palisading necrotic niche in GBM, and that this metabolic crosstalk promotes both GBM fitness and therapy resistance. Previous work has identified that the hypoxic pseudo-palisading niche contains glioma stem cells (GSC), which are generated by the hypoxic stress within these regions. Furthermore, Slc6a8 is directly regulated by hypoxia, suggesting creatine uptake exerts a role on GSC phenotypes. Thus, the first aim of this proposal is to examine how creatine transport influences GSC phenotypes in both human and mouse models of GBM. In this aim, we will also utilize inducible models of GBM that recapitulate the genetic and pathologic features of human GBM to determine if Slc6a8 is necessary for the formation of the hypoxic pseudo-palisading niche in tumors. Our preliminary data indicate that TAMCs isolated from both mice and humans with GBM are proficient producers of creatine. Furthermore, we found that this metabolic phenotype is specific to the tumor microenvironment (TME) and is induced by extracellular lactate. Thus, the second aim of this proposal will examine how the ablation of creatine biosynthesis by TAMCs controls tumor growth and progression in mouse models of GBM. This aim will also determine how lactate induces the creatine biosynthetic phenotype of TAMCs in GBM. The third aim of this proposal is to examine if a clinically relevant inhibitor of creatine transport influences GBM growth. We will test how this inhibitor works in the context of chemo and radiotherapy to determine how creatine uptake influences GBM recurrence. To establish translatable value from this work, we will generate tumor samples and patient-derived xenografts from patients, screen them for expression of creatine metabolic genes, then assess sensitivity to creatine metabolic inhibitory therapy. The results of this aim will identify if blocking TAMC-to-tumor metabolic communication is a feasible strategy for GBM therapy.