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引起的异常聚糖链的生物合成。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多种肿瘤细胞的运动和转移中起着重要作用。此外，许多这些异常聚糖是肿瘤相关碳水化合物抗原（TACA），并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在这些事件中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很好理解的特征是多价性的概念：单体碳水化合物与蛋白质的结合非常弱，而单体的“聚类”将这种亲和力提高了一百万倍。我们制备了重要的Thomsen-Friedenreich （Tf）抗原（Gal?O1-3GalNAc??）-O-Ser/Thr)来利用这种所谓的“簇糖苷效应”。如上一篇报道所述，我们制备了含糖衍生物的金自组装纳米球和量子点，并报道了其功能的初步细节。我们的金纳米球在小鼠体内的实验重复了两次，结果不同。然而，这是由于使用的肿瘤细胞具有与原始细胞不同的基因组成以及使用的肿瘤数量错误造成的。我们正在进行第四项研究，以确认最初的结果，并使用仅含有用于连接糖的连接单元的颗粒作为对照。我们的金纳米球含有？o-半乳糖可以在HIV细胞融合实验中模拟单价半乳糖，也证实了这些纳米结构的实用性。我们已经合成了生物学上重要的糖肽，并开发了新的连接技术将它们连接到金颗粒上。我们发现，我们需要在疏水肽中添加高水溶性的连接物，以克服产生多价和聚类的物理问题，这些物理问题会导致一些结构变得不可溶。在我们的量子点（qdots）工作中，我们证明了含有Tf抗原的量子点是功能性的，但我们需要开发一种技术来去除我们原始设计中的负电荷。这已经完成了，我们现在有了一个强大的连接体和发光增强技术，我们用它来在实验室里重新创造这些粒子。NCI的Chand Khanna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人员，因为负责大部分工作的原博士后突然离开了NCI，而寻找另一位有能力的研究员的时机推迟了工作。我们现在正在合成额外的粒子，为我们的合作者提供进一步的生物学表征。