Metabolic Resistance to Hypoxia in Glioblastoma Multiforme

摘要 恶性脑肿瘤胶质母细胞瘤(GBM)是患者和家庭因贫困而患的悲剧性疾病 预后，仅9.8%的患者存活超过5年。在生存方面只取得了一定的进步。 因此，尽管进行了几十年的研究，但仍需要更好地了解这种疾病的基本生物学。 改善患者的预后。低氧是基底膜和许多其他肿瘤的特征， 抗血管生成药物贝伐单抗，通常用于复发的GBM肿瘤。代谢变化 有助于适应肿瘤缺氧，并有可能成为降低治疗耐药性的靶向药物。我们的 初步数据显示，甘油三酯水平升高，超长链脂肪酸水平下降 高度缺氧性肿瘤。这表明使用了过氧异构体脂肪酸氧化，它主要是分解非常 长链脂肪酸，作为高度缺氧肿瘤的燃料来源。此外，此前的研究表明，缺氧 诱导前列腺癌细胞分泌载甘油三酯的胞外小泡。富含甘油三酯 细胞外小泡可能是缺氧时向GBM细胞输送燃料来源的一种潜在机制。我们 假设肾小球系膜细胞依赖过氧化脂肪酸氧化和甘油三酯负载的胞外小泡 低氧时促进肿瘤生长的分泌物。我们将通过我们的具体目标来研究这一假设：1) 过氧化脂肪酸氧化在抗血管生成药物诱导的低氧适应中的作用 基底膜肿瘤的治疗，以及2)确定细胞外囊泡形成和脂肪分泌在适应中的作用 抗血管生成治疗引起的基底膜肿瘤的低氧。为了达到这两个具体目标，我们将 1)体外测定低氧对细胞和细胞外小泡脂代谢的影响 代谢组学和信使核糖核酸分析，以及2)测试针对过氧酶体脂肪的联合抑制剂的有效性 体外和体内抗血管生成治疗的酸氧化或甘油三酯合成。在使用这些工具时 抑制剂，我们期望看到1)抑制暴露在低氧下的细胞的体外生长，以及2)抑制 抗血管生成治疗对肿瘤生长和生存期的影响及我们的抑制作用 与任何一种单独治疗相比。这些研究具有重要意义，因为它们将阐明机制 用于肿瘤生长和对治疗的耐药性。已确定的机制可以有针对性地纳入 针对GBM患者的创新治疗方案，可能会大幅提高存活率和 病人的幸福。

Abstract The malignant brain tumor Glioblastoma (GBM) is a tragic illness for patients and families due to poor patient prognosis, with only 9.8% of patients surviving past 5 years. Only modest gains in survival have been made despite decades of research, therefore, a better understanding of the basic biology of this disease is needed to improve patient outcomes. Hypoxia is characteristic of GBM and many other tumors, and is increased by the anti-angiogenic agent bevacizumab, which is commonly used for recurrent GBM tumors. Metabolic changes contribute to adaptation to tumor hypoxia, and can be potentially targeted to reduce treatment resistance. Our preliminary data shows elevated levels of triglycerides and decreased levels of very long chain fatty acids in highly hypoxic tumors. This suggests the use of peroxisomal fatty acid oxidation which primarily catabolizes very long chain fatty acids, as a fuel source in highly hypoxic tumors. In addition, previous studies show that hypoxia induces secretion of triglyceride-loaded extracellular vesicles in prostate cancer cells. Triglyceride-loaded extracellular vesicles may be a potential mechanism for delivering fuel sources to GBM cells during hypoxia. We hypothesize that GBM cells rely on peroxisomal fatty acid oxidation and triglyceride-loaded extracellular vesicle secretion to fuel tumor growth during hypoxia. We will investigate this hypothesis through our specific aims: 1) determine the effect of peroxisomal fatty acid oxidation in adaptation to hypoxia induced by anti-angiogenic treatment in GBM tumors, and 2) define the role of extracellular vesicle formation and lipid secretion in adaptation to hypoxia induced by anti-angiogenic treatment in GBM tumors. To address both of these specific aims, we will 1) determine the lipid metabolism effects of hypoxia on cells and extracellular vesicles in vitro using metabolomics and mRNA analysis, and 2) test the efficacy of combining inhibitors targeting peroxisomal fatty acid oxidation or triglyceride synthesis with anti-angiogenic treatment both in vitro and in vivo. When using these inhibitors, we expect to see 1) inhibition of cell growth in vitro in cells exposed to hypoxia, and 2) inhibition of tumor growth and extension of survival for tumors treated with anti-angiogenic treatment and our inhibitory agents, compared to either treatment alone. These studies are significant in that they will elucidate mechanisms for tumor growth and resistance to treatment. The identified mechanisms can be targeted and incorporated into innovative treatment regimens for GBM patients, potentially leading to substantial increases in survival and patient well-being.