Novel Approaches for Structural Determination of Cancer Stem Cell Glycans

描述(申请人提供)：胰腺癌预计今年将在美国造成32,000人死亡。如此高的死亡率在很大程度上是由于缺乏可靠的早期肿瘤检测方法，以及缺乏产生治愈的治疗选择。传统癌症治疗的一个并发症是，他们很容易错过被称为干细胞的一小部分细胞，而干细胞已被证明与肿瘤的增殖能力有关。蛋白糖基化异常与癌症的发生和发展有关。具体地说，含有唾液酸基和硫酸盐基团的酸性多糖经常被改变。有趣的是，最近发现的胰腺癌干细胞的细胞表面标志是糖蛋白。然而，由于与确定不稳定的、非均相的和分支的多糖的结构相关的巨大的分析挑战，用于产生新的诊断和治疗方法(包括癌症疫苗)所需的详细的癌症相关多糖结构是稀缺的。质谱仪(MS)可以提供灵敏、准确的多糖分析。然而，酸性分子MS的一个主要挑战是电离效率低。第二个挑战是确定糖的分支和特定的连接。此外，唾液酸和硫酸盐基团极不稳定，进一步影响了电离，使硫酸盐难以定位。这一应用侧重于开发新的MS方法来鉴定和结构表征由胰腺癌干细胞(潜在的生物标记物)唯一表达的多糖。具体地说，氧化锆和二氧化钛表面化学将被用来从复杂的混合物中富集唾液酸化和硫酸化的葡聚糖，从而大大改进它们对纳米级正相液相色谱傅里叶变换离子回旋共振(FTICR)MS的检测。为了确定这些葡聚糖的结构，我们将分别利用金属辅助电子捕获解离、电子解离和真空紫外光解离来增加糖的跨环裂解，这提供了连接信息，从而可以确定支化结构，并确定硫酸盐的位置。 与公共卫生相关：胰腺癌是美国的主要死亡原因，五年存活率为5%。这项研究致力于开发新的方法来改进存在于胰腺癌干细胞表面的碳水化合物(糖分子)的检测和结构确定，即肿瘤内负责其生长和繁殖能力的细胞子集。众所周知，碳水化合物在癌症中会发生变化，因此成为癌症疫苗开发的有希望的靶点。

DESCRIPTION (provided by applicant): Pancreatic cancer is expected to cause >32,000 deaths in he United States this year. This high mortality is largely due to lack of reliable methods for early tumor detection, and lack of treatment options that produce a cure. One complication with traditional cancer treatments is that they can easily miss the small subset of cells, termed stem cells, which have been shown to be responsible for a tumor's ability to proliferate. Aberrant protein glycosylation is linked to the onset and progression of cancer. Particularly, acidic glycans with sialic acid and sulfate groups are often altered. Interestingly, recently identified cell surface markers of pancreatic cancer stem cells are glycoproteins. However, due to tremendous analytical challenges associated with structural determination of labile, heterogeneous and branched glycans, detailed cancer-associated glycan structures, which are required for generation of novel diagnostics and therapeutics, including cancer vaccines, are scarce. Mass spectrometry (MS) can provide sensitive and accurate glycan analysis. However, a major challenge in acidic molecule MS is low ionization efficiency. A second challenge is the determination of saccharide branching and specific linkage. Also, sialic acids and sulfate groups are extremely labile, further compromising ionization and rendering sulfate localization difficult. This application focuses on developing novel MS approaches for identifying and structurally characterizing glycans uniquely expressed by pancreatic cancer stem cells (potential biomarkers). Specifically, zirconia and titania surface chemistry will be utilized to enrich sialylated and sulfated glycans from complex mixtures, thereby greatly improving their detection by nano-scale normal phase liquid chromatography Fourier transform ion cyclotron resonance (FTICR) MS. For structural determination of these glycans, we will utilize metal-assisted electron capture dissociation, electron detachment dissociation, and vacuum ultraviolet photodissociation, respectively, to increase sugar cross-ring cleavage, which provides linkage information and therefore allows determination of branched structures, and to determine sulfate location. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is a major death cause in the United States with a five-year survival rate of <5%. This research focuses on developing novel approaches for improved detection and structural determination of carbohydrates (sugar molecules) present on the surface of pancreatic cancer stem cells, that is, a subset of cells within a tumor that is responsible for its ability to grow and propagate. Carbohydrates are known to be altered in cancer and therefore constitute promising targets for cancer vaccine development.