Monosaccharide Analogs, Sialic Acid Metabolism and Apoptosis

描述（由申请人提供）：外源性单糖补充糖基化途径对从罕见先天性疾病（CDGs）到癌症等人类疾病具有潜在的治疗价值。特别是，调节细胞表面唾液酸显示的n -乙酰甘露糖胺（ManNAc）类似物是解决在各种癌症中发现的糖基化缺陷的有希望的候选者。糖类似物从目前的实验室工具到临床应用的转变最近得到了我们实验室最近的发现的推动，糖类似物诱导的毒性是通过用羟基保护基团修饰单糖来改善其药理特性引起的，这是由于细胞凋亡。这一观察结果，结合细胞凋亡刺激剂作为控制癌症的关键靶点的出现，支持加强研究唾液酸与细胞凋亡之间联系的努力：具体目标#1是表征ManNAc类似物在人类癌细胞凋亡中的作用，重点是n -酰基“R1”组的作用。这一目标将通过(A)测试类似物对O-GlcNAc蛋白修饰的影响；(B)逐步评估执行细胞凋亡的各种细胞通路对类似物的反应；(C)测试类似物对细胞“生物合成机制”的影响，细胞利用类似物构建一组参与凋亡的唾液糖缀合物，包括Fas、TNFalphaR2、IGF和CD43；(D)评估通过唾液酸生物合成途径抑制代谢通量是否是引起类似物诱导的细胞凋亡的原因或下游反应。Aim #1中概述的一系列实验旨在全面评估甘露聚糖类似物对唾液酸代谢的影响，并将这些反应与细胞凋亡联系起来。这些化合物还通过o -羟基“R2”基团修饰引起细胞范围的反应。在这个项目中，r2组的细胞反应（在摄入时将短链脂肪酸（SCFA）输送到细胞）将在Aim #2中进行测试：特定的Aim #2是通过(a)分析细胞对类似物提供的SCFA的反应，(B)表征SCFA“载体”分子的作用，(C)分析神经酰胺和神经节苷脂在类似物处理的细胞中的代谢，以及(D)测试r2组的代谢“携带”来表征r2组在细胞凋亡中的作用。

DESCRIPTION (provided by applicant): The supplementation of glycosylation pathways with exogenously-supplied monosaccharide has potential therapeutic value for human diseases ranging from rare congenital disorders (CDGs) to cancer. In particular, N-acetylmannosamine (ManNAc) analogs that modulate cell surface sialic acid display are promising candidates for addressing glycosylation defects found in a wide range of cancers. The transition of sugar analogs from their current status as laboratory tools to clinical applications has recently been given a boost by our laboratory's recent finding that sugar analog-induced toxicity observed upon modification of monosaccharide with hydroxyl-protecting groups designed to improve their pharmacological properties is due to apoptosis. This observation, combined with the emergence of apoptosis stimulators as key targets for the control of cancer, support enhanced efforts to investigate the connections between sialic acid and apoptosis: Specific Aim #1 is to characterize the role of ManNAc analogs in apoptosis in human cancer cells, with a focus on the effects of the N-acyl "R1" group. This goal will be pursued by (A) testing the impact of the analogs on O-GlcNAc protein modification; (B) performing a step by step evaluation of the response of the various cellular pathways that execute apoptosis to analogs; (C) testing the effects of analogs on the 'biosynthetic machinery' used by cells to construct a set of the sialoglycoconjugates involved in apoptosis that include Fas, TNFalphaR2, IGF, and CD43; and (D) evaluating whether inhibition of metabolic flux through the sialic acid biosynthetic pathway is the cause, or a downstream response, to analog-induced apoptosis. The set of experiments outlined in Aim #1 are designed to comprehensively evaluate the effects of ManNAc analogs on sialic acid metabolism and link these responses to apoptosis. These compounds also elicit cell-wide responses by virtue of O-hydroxyl "R2" group modifications. In this project, cellular responses of R2-groups, which deliver short chain fatty acids (SCFAs) to a cell upon intake, will be tested in Aim #2: Specific Aim #2 is to characterize the role of R2-groups in apoptosis by (A) analyzing cellular response to analog-supplied SCFAs, (B) characterizing the effects of the SCFA 'carrier' molecule, (C) analyzing ceramide and ganglioside metabolism in analog-treated cells and (D) testing metabolic 'carry-through' of R2-groups.