Implications of Metabolic Regulation of BCL-2 Dependence for Myeloma Therapy

项目总结 多发性骨髓瘤(MM)是一种浆细胞恶性肿瘤，占所有血液系统恶性肿瘤的13%， 在美国，每年有11,000人死亡，其中大多数死于疾病，原因是 抵抗。逃避细胞凋亡是肿瘤发生和耐药的核心。一个关键组件， 在大多数癌症中耐药的形成是由于bcl2家族的无效结合 细胞凋亡调节剂。诱导细胞凋亡的内在途径是由促凋亡因子的释放决定的 BH3-Only激活蛋白(BIM，PUMA，BID)来自抗凋亡的bcl2家族成员(bcl2，bclxl， MCL-1、BCL-w和A1)，进而激活Bax和BAK，导致线粒体膜通透性 和释放细胞色素C.BH3激活蛋白是通过减少一种抗 它们所结合的或致敏剂(如NOXA、BAD或BH3模拟物)所结合的凋亡性bcl2蛋白 释放BH3激活蛋白，使其与抗凋亡剂结合。当一个细胞在很大程度上具有抗凋亡剂时 受支持凋亡者的束缚(使其更接近凋亡者的临界值)，它“已做好死亡的准备”。抵抗的MM， 急性髓细胞性和淋巴细胞性白血病和各种实体肿瘤较不容易死亡。 这导致了阻力。从而找到替代策略来有效地使bcl2蛋白重新参与 增加启动状态可能会绕过阻力。葡萄糖和谷氨酰胺是关键的营养素 通过对bcl2蛋白的离散调控促进细胞增殖，更重要的是逃避细胞凋亡 如PUMA、BIM、NOXA、BAX、BAD和MCL-1。我们已经确定营养缺乏会导致 BCL-2家族的改变，有效地降低了凋亡阈值，即增加了“启动状态”。 比较代谢组学使识别具有潜在调节作用的代谢物的子集成为可能 BCL-2蛋白的表达及相互作用。抑制这一代谢途径的子集会敏化 多发性骨髓瘤细胞系和复发/难治患者样本的遗传多样性与BH3模拟类 小分子。此外，MM患者的基因表达谱检测显示上调 参与产生这些特定代谢物的酶，并隔离出较低水平的患者 总体存活率。我们将研究的中心问题之一是这些酶的表达如何升高 与实际代谢流量相关，以告知我们可操作的目标。这些观察结果构成了 我们描述了调控bcl2依赖的非冗余限速代谢酶的基本原理 揭示强大的代谢驱动的合成杀伤力策略，在给定较低的肿瘤细胞选择性的情况下 Bcl2对正常细胞的依赖性。因此，我们的长期目标是1)了解特定的新陈代谢 酶调节bcl-2蛋白家族和2)证明了 靶向多发性骨髓瘤的代谢途径以规避耐药性。

PROJECT SUMMARY Multiple myeloma (MM) is a plasma cell malignancy accounting for 13% of all hematological malignancies and 11,000 deaths annually in the US, with the majority succumbing to disease due to the development of resistance. Evasion of apoptosis is central to tumor development and resistance. A key component to the development of resistance across most cancers lies in the ineffective engagement of the BCL-2 family of apoptosis regulators. Induction of the intrinsic pathway of apoptosis is dictated by the release of pro-apoptotic BH3-only activator proteins (BIM, PUMA, BID) from anti-apoptotic BCL-2 family members (BCL-2, BCL-xL, MCL-1, BCL-w and A1) that in turn activate BAX and BAK leading to mitochondrial membrane permeabilization and release of cytochrome C. BH3 activator proteins are released either by reduction in expression of an anti- apoptotic BCL-2 protein to which they are bound or if a sensitizer (such as NOXA, BAD or a BH3 mimetic) releases the BH3 activator protein from binding the anti-apoptotic. When a cell has its anti-apoptotics largely bound by pro-apoptotics (bringing it closer to the apoptotic threshold) it is “primed for death”. Resistant MM, acute myelogenous and lymphocytic leukemia and various solid tumors are found to be less primed for death that contributes to resistance. Thus finding alternative strategies to effectively re-engage BCL-2 proteins to increase the primed state can potentially circumvent resistance. Glucose and glutamine are key nutrients promoting proliferation and importantly, evasion of apoptosis through discrete regulation of BCL-2 proteins such as PUMA, BIM, NOXA, BAX, BAD and MCL-1. We have determined that nutrient deprivation leads to BCL-2 family alterations that effectively lower the apoptotic threshold i.e. increase the “primed state”. Comparative metabolomics enabled identification of a subset of metabolites with potential roles in regulating BCL-2 protein expression and interactions. Inhibition of this subset of metabolic pathways sensitized a genetically diverse panel of MM cell lines and relapse/refractory patient samples to the BH3 mimetic class of small molecules. Furthermore, examination of gene expression profiles of MM patient's revealed upregulation of the enzymes involved in generation of these specific metabolites and segregated out patients with lower overall survival. One of the central questions we will investigate is how elevated expression of these enzymes correlates with actual metabolic flux to inform us of actionable targets. These observations form the basis of our rationale that delineating non-redundant rate-limiting metabolic enzymes regulating BCL-2 dependence will reveal strategies of potent metabolically-driven synthetic lethality with selectivity for tumor cells given the lower BCL-2 dependence of normal cells. Therefore, our long-term goals are to 1) understand how specific metabolic enzymes regulate the BCL-2 family of proteins and 2) demonstrate the feasibility and therapeutic promise of targeting metabolic pathways in MM to circumvent resistance.