An Untested Approach: Biomarkers for Colon Cancer

癌症研究中最苛刻的领域之一是寻找生物标记物来早期检测癌症 癌症。众所周知，癌症与糖偶联物糖基化模式的改变有关。 包括糖脂和糖蛋白。基于这一观察，该项目的目标是确定 用于结肠癌早期检测和预后评估的新型粘液生物标志物。我们的方法 与识别癌症相关多糖的传统方法不同之处在于，我们检查了 并利用这一信息和我们对甘氨酸生物合成途径的知识来 预测可能的候选生物标记物。这项研究的总体假设是“大脑结构的变化 癌症相关的多糖是由细胞表达的根本性变化驱动的 参与其生物合成的糖基转移酶。癌细胞表达不同的糖基转移酶 导致了明显的幸灾乐祸的签名。 为了支持上述概念，我们进行了研究，以测定岩藻糖基-，(3-N- 不同结肠癌细胞系中乙酰半乳糖氨基、唾液酸基和磺基转移酶，以及正常和 癌变的结肠组织。这些研究集中在那些能产生细胞外端的酶。 糖链中的低聚糖链。在这些研究中，我们一致地观察到两种截然不同的 癌组织中GAL：3-O-磺酸转移酶。其中一种酶介导了SE3-的形成。 Gal|3GalNAca型结构和其他介导的SE3-Gal|31？4GlcNAc末端单元的形成 在粘蛋白核心2四糖Gal(31，4GlcNAc(31，6)Gal(31，3)GalNAca-.这些组织还展示了 (1，3)岩藻酰基转移酶和(2，3)唾液酸基转移酶的显著水平。基于对癌症的这些研究 细胞系和组织，我们选择了独特表达的新型硫酸盐碳水化合物表位，这些表位 可能存在于结肠癌，但不存在于正常细胞。我们认为这些硫酸化的多糖提供了新的 结肠癌治疗和检测的靶点。为了确认这一可能性，我们建议 合成选定的硫酸盐碳水化合物抗原，并将其与KLH连接。单抗将会是 针对这些目标结构开发的。最后，这些抗体将应用于结肠细胞系和 临床标本，以评估其在识别新的结肠相关抗原方面的有效性。我们的合成材料 Capability还提供了一系列寡糖来确定新抗体的特异性 试剂，因此这些试剂可能不仅对结肠癌的研究有用，而且对其他 癌症和血管生物学领域的问题。独有的单抗的产生 结肠癌细胞的硫酸葡聚糖可导致新的诊断策略。目前没有血清 结肠癌的标志物，因此我们的项目也将研究血清中的硫酸多糖是否在 结肠癌。这个项目的成功结果将把我们引向未来的结肠癌项目， 包括使用癌细胞上表达的葡聚糖作为癌症治疗的靶点。

One of the most demanding areas of cancer research is finding biomarkers for the early detection of cancer. It is known that cancer is associated with alterations in the glycosylation patterns of glycoconjugates including glycolipids and glycoproteins. Based on this observation, the objective of this project is to identify novel mucinous biomarkers for the early detection and prognostic evaluation of colon cancer. Our approach differs from conventional methods of identifying cancer-associated glycans in that we examine the level of cellular glycosylation and use this information along with our knowledge of glyean biosynthetic pathways to predict likely candidate biomarkers. The overall hypothesis of the study is that "Changes in the structures of cancer-associated glycans are driven by fundamental changes in the cellular expression of the glycosyltransferases involved in their biosynthesis. Cancer cells express different glycosyltransferases leading to disticnt glyean signatures." In support of the above concept, we performed studies to assay the activity of fucosyl-,(3-N- acetylgalactosaminyl-, sialyl- and sulfotransferases in different colon cancer cell lines, and normal and cancerous colon tissue. These studies focused on those enzymes that generate the outer ends of the oligosaccharide chains in glycans. In these studies, we consistently observed elevated levels of two distinct Gal:3-O-sulfotransferases in cancerous tisue. One of these enzymes mediated formation of SE3- Gal|31¿>3GalNAca- type structure and the other mediated formation of SE3-Gal|31¿>4GlcNAc terminal units in the mucin core 2 tetrasaccharide Gal(31,4GlcNAc(31,6(Gal(31,3)GalNAca-. These tissues also exhibited appreciable levels of a(1,3)fucoyltranferase and a(2,3)sialyltranferase. Based on these studies from cancer cell lines and tissues, we have selected uniquely expressed novel sulfated carbohydrate epitopes that are likely present on colon cancer but not normal cells. We propose that these sulfated glycans provide novel targets for treatment and detection of colon cancer. In order to confirm this possibility, we propose to synthesize selected sulfated carbohydrate antigens and link them to KLH. Monoclonal antibodies will be developed against these target structures. Finally, these antibodies will be applied to colon cell lines and clinical specimens to assess their efficacy in identifying novel colon associated antigens. Our synthetic capability also provides a series of oligosaccharides to determine the specificity of the new antibody reagents, and thus these reagents are likely to be useful not only for studies of colon cancer.but also other problems in the fields of cancer and vascular biology. Generation of monoclonal antibodies unique to sulfated glycans of colon cancer cells can lead to new diagnosis strategies. There are currently no serum markers of colon cancer, and thus our project will also study if sulfated glycans in serum are elevated during colon cancer. The successful outcome of this program will lead us to a future program on colon cancer that includes the use of glycans expressed on cancer cells as targets for cancer therapy.