Functional Analysis of Galectin-1 Ligands in Melanoma Progression

描述（由申请方提供）：细胞表面碳水化合物和与之结合的蛋白质（凝集素）在某些恶性肿瘤中显著升高。这些糖结构和凝集素与癌细胞运动、侵袭和/或迁移密切相关，最终引起癌症的致死性。有令人信服的证据表明，β-半乳糖苷结合凝集素，半乳糖凝集素-1（Gal-1），是黑色素瘤进展和转移的主要糖致病介质。研究表明，黑色素瘤来源的Gal-1对T细胞介导的抗黑色素瘤免疫具有重要影响。虽然大多数人都集中在Gal-1和它的功能活性在这些恶性肿瘤相关的事件，很少有集中在功能表达的Gal-1碳水化合物结合决定簇上发现的黑色素瘤细胞的表面。我们有令人兴奋的初步数据显示，人类黑色素瘤细胞表达了一个强大的Gal-1结合碳水化合物的水平，包括显示它们的膜蛋白，令我们惊讶的是，在正常黑色素细胞和良性黑色素细胞中明显缺乏轻度发育异常痣。此外，我们有实验证据表明，黑色素瘤细胞粘附分子（MCAM）是主要的膜糖蛋白显示这些Gal-1结合的碳水化合物，也上调恶性黑色素瘤。因此，这些Gal-1结合碳水化合物在不同糖蛋白上的差异表达，在操作上称为Gal-1配体，可能在功能上与人黑色素瘤的恶性进展相关。我们的中心假设是，Gal-1配体，即MCAM，在黑色素瘤细胞上的表达不仅可以用作黑色素瘤进展的生物标志物，而且可以在功能上与恶性转化相关。本研究项目的总体目标是分析Gal-1配体对人恶性黑色素瘤细胞的特性、调节和功能，并研究Gal-1配体作为人黑色素瘤进展和转移的预测因子的效用。研究人类黑色素瘤中Gal-1配体的身份和功能，以及这些结构是否与黑色素瘤患者的疾病严重程度和长期结局相关，可以由肿瘤生物学家和皮肤病理学家合作提出。本研究利用本实验室开发的新型Gal-1配体结合探针和我们在鉴定凝集素配体和研究黑色素瘤组织病理学方面的集体专业知识，具体目的如下：（1）鉴定和表征人黑色素瘤中的Gal-1配体和（2）研究Gal-1配体的表达作为黑色素瘤进展的预测因子。这些研究将实施来自澳大利亚黑色素瘤研究所的人类黑色素瘤组织的独特队列，以帮助确定Gal-1配体表达是否与黑色素瘤进展和转移相关。此外，我们将采用最先进的糖生物学工具来帮助剖析Gal-1配体的身份和功能。重要的是，我们的研究结果将为黑色素瘤的糖组织病理学提供新的分子见解，同时为预测恶性肿瘤和/或临床结果提供新的糖组学靶点。

DESCRIPTION (provided by applicant): Cell surface carbohydrates and proteins (lectins) that bind them are conspicuously elevated in certain malignancies. These sugar structures and lectins are critically involved in cancer cell motility, invasion and/or migration that ultimately evoke the lethality of cancer. There is a convincing body of evidence suggesting that ss-galactoside-binding lectin, galectin-1 (Gal-1), is a major glycopathogenic mediator of melanoma progression and metastasis. Studies show that melanoma-derived Gal-1 has a major impact on T cell-mediated anti-melanoma immunity. While most have focused on Gal-1 and its functional activity in these malignancy-related events, few have focused on the functional expression of Gal-1 carbohydrate-binding determinants found on the surface of melanoma cells. We have exciting preliminary data showing that human melanoma cells express a robust level of Gal-1-binding carbohydrates, including the membrane protein(s) that display them, that, to our surprise, are conspicuously absent on normal melanocytes and benign melanocytes in mildly dysplastic nevi. Moreover, we have experimental evidence indicating that melanoma cell adhesion molecule (MCAM) is the principal membrane glycoprotein displaying these Gal-1-binding carbohydrates that is also upregulated in malignant melanoma. Differential expression of these Gal-1-binding carbohydrates on distinct glycoproteins, operationally referred to as Gal-1 ligands, could, therefore, functionally correlate with malignant progression of human melanoma. Our central hypothesis is that expression of Gal-1 ligands, namely MCAM, on melanoma cells can not only be used as a biomarker of melanoma progression, but can be functionally associated with malignant transformation. The overall objective of this research project is to analyze the identity, regulation and function of Gal-1 ligands on human malignant melanoma cells and to study the utility of Gal-1 ligands as predictors of human melanoma progression and metastasis. Investigating identity and function of Gal-1 ligands in human melanomas and whether these structures correlate with disease severity and long-term outcome in melanoma patients can be uniquely applied by the tumor biologists and dermato-pathologists collaborating in this proposal. Using new Gal-1 ligand-binding probes developed by our laboratory and our collective expertise in identifying lectin ligands and studying the histopathology of melanomas, the Specific Aims are as follows: (1) To identify and characterize Gal-1 ligands in human melanomas and (2) To study the expression of Gal-1 ligands as predictors of melanoma progression. These studies will implement a unique cohort of human melanoma tissues from the Melanoma Institute of Australia to help determine whether Gal-1 ligand expression correlates with melanoma progression and metastasis. Moreover, we will employ state-of-the-art glycobiological tools to help dissect Gal-1 ligand identity and function. Importantly, our findings will provide novel molecular insights into the glyco-histopathology of melanomas, while offering new glycomic targets for predicting malignancy and/or clinical outcome.