NMR Group Project: Preparation and Properties of Novel M

NMR 课题组项目：Novel M 的制备及性能

• 批准号: 7291828
• 负责人: Joseph John Barchi
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7291828
• 关键词: NMR; Group; Project; Preparation; Properties

An established hallmark of tumorigenesis is the biosynthesis of aberrant glycan chains due to changes in the expression of glycoprocessing enzymes in tumor tissue. These aberrations become more marked as the tumor acquires a more aggressive phenotype. Tumor cell-surface carbohydrates play important roles in the motility and metastasis of many different cancer cells. In addition, many of these aberrant glycans are tumor-associated carbohydrate antigens (TACA) and have been used in the development of tumor vaccines. Since most of the cellular interactions with TACA's are not well understood, there is an urgent need to better characterize the specific molecular interactions that occur during these events. One feature of carbohydrate binding to macromolecules that is well understood is the concept of multivalency: Monomer carbohydrates bind to proteins very weakly while "clustering" of a monomer raises this affinity as much as a million-fold. We have prepared the important Thomsen-Friedenreich (Tf) antigen (Gal?O1-3GalNAc??-O-Ser/Thr) on very specific templates to take advantage of this so-called "cluster glycoside effect". As mentioned in the last report, we have prepared gold self-assembled nanospheres and quantum dots containing sugar derivative and reported preliminary details on their function. The in vivo experiments with our gold nanospheres in mice were repeated twice with varying results. However, these were caused by the use of a tumor cells that had had a different genetic makeup than the original and an error in the amount of tumor used. We are proceeding with a 4th study to confirm the original results along with using particles that contain simply the linker unit used to attach the sugar as a control. Our gold nanospheres containing ?O-galactose can mimic monovalent galactose in HIV cell fusion assays, also confirming the utility of these nano-constructs. We have synthesized biologically important glycopeptides and developed new linker technology to attach these to gold particles. We discovered that we need to add highly water soluble linkers to peptides that are hydrophobic to overcome the physical problems with the creation of multivalency and clustering that causes some constructs to become insoluble. In our quantum dots (qdots) work, we showed that contain Tf antigen-containing Qdots are functional but we needed to develop technology that removed the negative charge on our original design. This was accomplished and we now have a robust linker and luminescent-enhancing technology that we use to create these particles de novo in the lab. Further imaging studies with Chand Khanna at NCI have shown that these particles can label tumor cells that express galectin-3 and possible cause these cells to become apoptotic. We are continuing these studies with several collaborators. In this past year, we spent half of the time without a full time researcher since the original post doc who developed most of the work left the NCI suddenly and the timing to secure another able fellow delayed the work. We are now synthesizing additional particles to supply our collaborators for further biological characterization.

肿瘤发生的一个既定标志是由于肿瘤组织中糖加工酶表达的变化而生物合成异常聚糖链。当肿瘤获得更具侵袭性的表型时，这些畸变变得更加明显。肿瘤细胞表面碳水化合物在许多不同癌细胞的运动和转移中发挥重要作用。此外，许多异常聚糖是肿瘤相关糖抗原（TACA），已用于肿瘤疫苗的开发。由于大多数细胞与 TACA 的相互作用尚不清楚，因此迫切需要更好地表征这些事件期间发生的特定分子相互作用。碳水化合物与大分子结合的一个众所周知的特征是多价概念：单体碳水化合物与蛋白质的结合非常弱，而单体的“聚集”则将这种亲和力提高了数百万倍。我们在非常特异的模板上制备了重要的 Thomsen-Friedenreich (Tf) 抗原 (Gal?O1-3GalNAc??-O-Ser/Thr)，以利用这种所谓的“簇糖苷效应”。正如上一篇报告中提到的，我们制备了金自组装纳米球和含有糖衍生物的量子点，并报告了其功能的初步细节。我们的金纳米球在小鼠体内的体内实验重复了两次，结果各不相同。然而，这些都是由于使用的肿瘤细胞的基因组成与原始细胞不同以及肿瘤细胞用量的错误造成的。我们正在进行第四项研究，以确认最初的结果，并使用仅包含用于连接糖的连接单元的颗粒作为对照。我们的含有 β-半乳糖的金纳米球可以在 HIV 细胞融合测定中模拟单价半乳糖，也证实了这些纳米结构的实用性。我们合成了具有生物学重要意义的糖肽，并开发了新的连接技术，将它们附着在金颗粒上。我们发现，我们需要向疏水性肽添加高度水溶性的连接体，以克服多价和聚类产生的物理问题，从而导致某些构建体变得不溶。在我们的量子点 (qdot) 工作中，我们证明含有 Tf 抗原的 Qdot 是有功能的，但我们需要开发技术来消除我们原始设计上的负电荷。这已经完成，我们现在拥有强大的连接器和发光增强技术，我们可以使用它们在实验室中从头创建这些粒子。 NCI 的 Chand Khanna 进行的进一步成像研究表明，这些颗粒可以标记表达半乳糖凝集素 3 的肿瘤细胞，并可能导致这些细胞凋亡。我们正在与几位合作者继续进行这些研究。在过去的一年里，我们有一半的时间没有全职研究员，因为负责大部分工作的最初博士后突然离开了 NCI，而寻找另一位有能力的研究员的时间推迟了工作。我们现在正在合成更多的颗粒，为我们的合作者提供进一步的生物学表征。