Lactate Transport as a Therapeutic Target in Glioma

描述（由申请人提供）：糖酵解速率异常高，即，快速消耗葡萄糖并代谢为乳酸，是所有恶性肿瘤的标志。 我们的长期目标是阐明这种异常行为的分子基础，并利用这些知识开发针对多形性胶质母细胞瘤（GBM）的治疗策略，GBM是最恶性和致命的脑肿瘤。 我们假设这些肿瘤对乳酸流出的抑制将削弱它们的代谢并导致它们的死亡，基于我们的观察：1]乳酸被GBM大量流出到肿瘤微环境中，2]与正常脑组织相比，特异性乳酸转运蛋白同种型在GBM中高度表达，3]在GBM衍生的细胞系中抑制乳酸转运蛋白表达或其功能，无论是在体外还是在体内，都停止了它们排出乳酸的能力，并导致它们的快速破坏。 具体目标是：1.确定调节GBM中乳酸转运蛋白表达的关键信号通路。 MCT 2的启动子（主要在GBM中表达的乳酸转运蛋白）将用作区分所涉及的初级代谢产物和反式激活因子的模型。 2.研究乳酸外排如何影响GBM的侵袭潜力。 最近发现乳酸影响肿瘤细胞外基质的重塑。 我们将通过器官型脑切片培养来查询神经胶质瘤微环境，以通过乳酸诱导关键基质和肿瘤衍生的蛋白酶，并将其对侵袭过程的影响关联起来。 3.检查红细胞生成常见的信号通路如何与MCT 2启动子相互作用。 在红细胞生成基因中常见的顺式作用元件在近端MCT2启动子上最多产。 我们将研究这些基序和它们的反式作用因子如何调节GBM中的MCT 2表达，以及它们存在的理由。 4.开发一种用于快速筛选小分子药物的体外细胞测定法，以鉴定新型乳酸转运蛋白抑制剂。 肉桂酸的衍生物是唯一已知的乳酸转运蛋白的竞争性抑制剂。 我们将利用基于凝胶微囊化细胞的技术来设计用于筛选小分子化学文库的体外测定，以鉴定靶向乳酸转运的新药。 在美国，每年有超过17，000人，大多数是3至12岁的儿童和40至70岁的成年人，发现他们患有恶性脑癌。 不幸的是，90%的人仍然在6到12个月内死亡，即使在手术，放射治疗和化疗之后。 因此，我们需要新的方法来靶向这种致命的癌症。 我们计划测试一种新的方法来“腌制肿瘤致死”，同时保持健康的脑细胞完好无损。

DESCRIPTION (provided by applicant): An abnormally high rate of glycolysis, i.e., rapid consumption of glucose and metabolism to lactic acid, is a hallmark of all malignant tumors. Our long-term goal is to elucidate the molecular basis for this aberrant behavior, and harness that knowledge towards development of therapeutic strategies against glioblastoma multiforme (GBM), the most malignant and lethal of brain tumors. We hypothesize that inhibition of lactate efflux by these tumors will debilitate their metabolism and cause their death, based on our observations that 1] lactic acid is effluxed to the tumor microenvironment in large quantities by GBMs, 2] specific lactate transporter isoforms are highly expressed in GBMs in contrast to normal brain tissue, 3] inhibition of lactate transporter expression or their function in GBM derived cell lines, both in vitro and in vivo, halted their ability to efflux lactic acid, and resulted in their rapid destruction. The specific aims are to: 1. Identify the key signaling pathways that regulate lactate transporter expression in GBMs. Promoter of MCT2, the lactate transporter predominantly expressed in GBMs, will be used as the model to distinguish the primary metabolites and trans-activating factors that are involved. 2. Investigate how lactate efflux affects the invasive potential of GBMs. Lactic acid was recently identified to influence the remodeling of extracellular matrix by tumors. We will query the glioma micro-environment via organotypic brain-slice cultures for induction of key stromal and tumor-derived proteases by lactic acid, and correlate the effects on the invasive process. 3. Examine how signaling pathways common to erythropoiesis interact with the MCT2 promoter. Cis-acting elements common in erythropoietic genes are the most prolific on the proximal MCT2 promoter. We will investigate how these motifs and their trans-acting factors regulate MCT2 expression in GBMs, and the rationale for their presence. 4. Develop an in vitro cellular assay for rapid screening of small molecule drugs to identify novel lactate transporter inhibitors. Derivatives of cinnamic acid are the only known competitive inhibitors of lactate transporters. We will utilize gel micro-encapsulated-cell based techniques to design an in vitro assay for screening of small molecule chemical libraries to identify new drugs to target lactate transport. Every year more than 17,000 people in the US, mostly children 3 to 12 years old, and adults 40 to 70 years old, find out they have malignant brain cancer. Tragically, 90% of them still die within 6 to 12 months, even after surgery, radiation treatment, and chemotherapy. Thus, we need new ways to target this deadly cancer. We plan to test a novel method to "pickle-the-tumor-to-death," while leaving healthy brain cells intact.