Metabolic Regulators of Tumor Cell Growth

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）是成人中最致命的脑癌形式。尽管最近关于这种疾病的遗传原因的信息激增，但GBM患者的平均生存期只有15个月，并且肿瘤往往对所有已知的疗法具有抗性。GBM的破坏性强调了对新的治疗靶点的迫切需要，以及对驱动这些肿瘤生长和维持的分子机制的更好理解。与其他侵袭性肿瘤一样，GBM显示出高度的细胞增殖，这是通过激活一组选定的代谢活动来产生细胞生长和分裂所需的能量和大分子（脂质、核酸、蛋白质）而实现的。这些代谢活性是有吸引力的治疗靶点，因为它们位于GBM中细胞转化的不同分子驱动因素和最终杀死患者的快速肿瘤生长表型之间。本提案的主要目的是确定体外和体内GBM细胞生长的代谢调节剂。该提案建立在我们开发的新分析方法的基础上，该方法用于测量培养物中GBM细胞的代谢，并首次在小鼠中生长的完整人类GBM肿瘤中进行。这些方法导致了令人惊讶的观察结果，即GBM细胞具有高度活性的线粒体，其使用两种代谢途径中的任一种将营养物质转化为大分子合成和生长所需的前体。具体目标1提出了RNA干扰的功能丧失实验，以确定关键的代谢调节因子，使GBM细胞使用氨基酸谷氨酰胺作为首选的线粒体底物。具体目标2提出了类似的实验，以确定替代代谢途径中的关键代谢调节因子，该途径不需要谷氨酰胺，但仍允许肿瘤细胞在培养物和体内快速生长。具体目标3提出研究仅在小鼠脑中生长的20个独立的人GBM肿瘤的代谢，以了解肿瘤突变如何影响代谢活性，以及特定突变是否定义了对体内代谢活性抑制的敏感性。所有三个特定目标都使用核磁共振光谱和质谱对活肿瘤进行了广泛的代谢分析，并将以前所未有的详细程度和生物准确性对GBM代谢进行独特的观察。总之，这些实验将确定一组新的代谢活动，将GBM肿瘤与正常大脑区分开来，将定义将恶性转化与细胞代谢联系起来的机制，并将确定代谢靶点，这些靶点将导致GBM和潜在的其他侵袭性癌症的新治疗方法。

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM) is the most lethal form of brain cancer in adults. Despite a recent explosion of information on the genetic causes of this disease, the average survival of GBM patients is only 15 months and the tumors tend to be resistant to all known therapies. The devastating nature of GBM underscores a dire need for novel therapeutic targets and a better understanding of the molecular mechanisms that drive the growth and maintenance of these tumors. Like other aggressive tumors, GBMs display a high degree of cell proliferation made possible by the activation of a select set of metabolic activities required to generate the energy and macromolecules (lipids, nucleic acids, proteins) needed for cell growth and division. These metabolic activities are attractive therapeutic targets because they lie between the diverse molecular drivers of cellular transformation in GBM and the phenotype of rapid tumor growth that ultimately kills the patient. The main objective of this proposal is to define the metabolic regulators of GBM cell growth in vitro and in vivo. The proposal builds on our novel analytical methods developed to measure metabolism of GBM cells in culture and, for the first time, in intact human GBM tumors grown in the mouse. These methods led to the surprising observation that GBM cells have highly active mitochondria that use either of two metabolic pathways to convert nutrients into precursors required for macromolecular synthesis and growth. Specific Aim 1 proposes loss-of-function experiments with RNA interference to identify key metabolic regulators that allow GBM cells to use the amino acid glutamine as the preferred mitochondrial substrate. Specific Aim 2 proposes similar experiments to define the key metabolic regulators in an alternative metabolic pathway that does not require glutamine but still allows tumor cells to grow rapidly in culture and in vivo. Specific Aim 3 proposes to study metabolism in twenty independent human GBM tumors grown exclusively in the mouse brain to understand how tumor mutations influence metabolic activity, and whether particular mutations define sensitivity to the suppression of metabolic activities in vivo. All three Specific Aims feature extensive metabolic analysis of live tumors using nuclear magnetic resonance spectroscopy and mass spectrometry, and will produce a unique view of GBM metabolism with an unprecedented level of detail and biological accuracy. Together, these experiments will pinpoint a new set of metabolic activities that distinguish GBM tumors from normal brain, will define mechanisms that connect malignant transformation to cellular metabolism, and will identify metabolic targets that should lead to novel therapeutic approaches in GBM and potentially other aggressive cancers.