Targeting Ceramide Glycosylation in AML

鞘脂神经酰胺是一种有效的肿瘤抑制剂，有助于促进细胞凋亡， 自噬癌细胞中这些反应的管理取决于以下因素之间的动态平衡： 神经酰胺，其是促凋亡的及其代谢物，其可以促进细胞存活。上调 神经酰胺的糖基化是神经酰胺解毒的主要途径， 神经酰胺的抑制作用。该提案将重点关注减少神经酰胺糖基化，目标是 设计新的神经酰胺疗法用于治疗急性髓性白血病（AML）， 成人白血病上调神经酰胺激动剂与白血病多药耐药相关。在 我们的研究将以短链、细胞可渗透的C6-神经酰胺（C6-cer）的形式外源性使用神经酰胺。 纳米脂质体，一种提供优于其它递送系统或使用天然神经酰胺的优点的系统， 其由于溶解度和运输限制而不能外源性给药。我们的目标是 开发治疗AML的创新方法，这将通过提供C6-cer与 与将减弱代谢并由此放大神经酰胺驱动的细胞死亡的佐剂一起使用。以衰减 C6-cer代谢，我们将采用P-糖蛋白（P-gp）拮抗剂作为佐剂。我们假设 由于其在糖脂运输中作用，细胞内P-gp将是一种非常有效的靶点， C6-cer代谢我们还假设，P-gp拮抗剂将增加细胞内的水平， C6-cer和长链神经酰胺并放大终点反应（凋亡、自噬、细胞周期停滞）。 由于P-gp在调节短链神经酰胺代谢中的主要作用，本项目 通过引入P-gp拮抗剂作为神经酰胺调节剂，标志着临床策略的转变 代谢和神经酰胺细胞毒性的增强剂，一个活动脱离了许多研究 化疗流出/多药耐药蛋白，我们都知道。为了使纳米脂质体C6-cer 作为AML的有效治疗剂，将追求以下目标：1）确定P-gp的影响 AML细胞模型中C6-cer细胞毒性和代谢的表达。理解P的关系- gp和细胞对C6-cer的应答对于优化基于神经酰胺的治疗是至关重要的。2)确定 抑制C6-cer催化剂对确定AML细胞系和患者中对C6-cer的细胞毒性应答的影响 细胞我们假设阻断C6-cer催化剂，包括转化为鞘磷脂， 协同增强细胞毒性。3)阐明细胞死亡的机制和信号事件 与AML细胞中C6-cer/P-gp拮抗剂组合的细胞毒性相关。4)确定影响的 佐剂抑制剂对体内AML小鼠模型中C6-cer治疗的反应。功能障碍性神经酰胺 代谢促进对细胞凋亡的抗性。我们希望发现，纳米脂质体C6-cer 与P-gp拮抗剂（阻断神经酰胺激动剂）联合使用将是一种新颖、创新、无毒的治疗方法， 急性髓细胞白血病 相关性（参见说明）： 急性骨髓性白血病（AML）是成人中最常见的白血病类型，是一种侵袭性癌症， 只有约25%的经历化疗缓解的患者保持无病。有 因此，公共卫生迫切需要开发有效的治疗方法， 一种情况下，提供治疗。这个项目将通过评估新的药物组合来解决这个问题 旨在加强和增强杀死白血病细胞而不伤害正常细胞的生化信号。

The sphingolipid ceramide is a potent tumor suppressor that contributes to the promotion of apoptosis and autophagy. Management of these responses in cancer cells is dependent on the dynamic balance between ceramide which is pro-apoptotic and its metabolites, which can promote cell survival. Upregulated glycosylation of ceramide, a major pathway contributing to ceramide detoxification, limits the valuable tumor suppressor effects of ceramide. This proposal will focus on reducing ceramide glycosylation with the goal of devising novel ceramide therapies for treatment of acute myeloid leukemia (AML), the most common type of leukemia in adults. Upregulated ceramide catabolism is associated with multidrug resistance in leukemia. In our study we will use ceramide exogenously in the form of short-chain, cell-permeable C6-ceramide (C6-cer) nanoliposomes, a system that offers advantages over other delivery systems or the use of natural ceramide, which due to solubility and transport limitations, cannot be administered exogenously. Our objective is to develop innovative approaches for treating AML, and this will be achieved by delivering C6-cer in conjunction with adjuvants that will attenuate metabolism and thereby amplify ceramide-driven cell death. To attenuate C6-cer metabolism, we will employ P-glycoprotein (P-gp) antagonists as adjuvants. We hypothesize that intracellular P-gp, because of its role in glycolipid trafficking, will be a highly effective target for attenuating C6-cer metabolism.. We also hypothesize that P-gp antagonists will increase the intracellular levels of both C6-cer and long-chain ceramides and magnify end-point responses (apoptosis, autophagy, cell cycle arrest). Because of the major role that P-gp plays in regulating the metabolism of short-chain ceramides, this project hallmarks a shift in clinical strategy by introducing the use of P-gp antagonists as modulators of ceramide metabolism and enhancers of ceramide cytotoxicity, an activity divorced from the much investigated chemotherapy effluxing/multidrug resistance protein we all know. To make nanoliposomal C6-cer more effective as a therapeutic in AML, the following aims will be pursued: 1) Determine the influence of P-gp expression on C6-cer cytotoxicity and metabolism in AML cell models. Understanding the relationship of P- gp and cellular response to C6-cer is critical for optimizing ceramide-based therapeutics. 2) Determine the effect of inhibiting C6-cer catabolism on cytotoxic response to C6-cer in defined AML cell lines and patient cells. We hypothesize that blocking C6-cer catabolism, including conversion to sphingomyelin, will synergistically amplify cytotoxicity. 3) Elucidate the mechanism of cell death and the signaling events associated with cytotoxicity of combination C6-cer/P-gp antagonists in AML cells. 4) Determine the effect of adjuvant inhibitors on response to C6-cer therapy in in vivo AML mouse models. Dysfunctional ceramide metabolism promotes resistance to apoptosis. We expect to discover that partnering nanoliposomal C6-cer with P-gp antagonists (that block ceramide catabolism) will be a novel, innovative, non-toxic treatment for AML. RELEVANCE (See instructions): Acute myelogenous leukemia (AML), the most common type of leukemia in adults, is an aggressive cancer, and only about 25% of patients who experience remission with chemotherapy remain disease-free. There is thus a pressing need in public health to develop effective therapies that can extend remission and in the best case scenario, offer cure. This project will address this issue by evaluating novel combinations of agents designed to reinforce and potentiate biochemical signals that kill leukemia cells without harm to normal cells.