Inamdar Shashikala R, Eligar Sachin M, Ballal Suhas, Belur Shivakumar, Kalraiya Rajiv D, Swamy Bale M
Department of Studies in Biochemistry, Karnatak University, Dharwad, -580 003, India.
Advanced Centre for Treatment, Research and Education in Cancer, Kharghar, Navi Mumbai, 410210, India.
Glycoconj J. 2016 Feb;33(1):19-28. doi: 10.1007/s10719-015-9628-0. Epub 2015 Oct 29.
Lectins are carbohydrate binding proteins that are gaining attention as important tools for the identification of specific glycan markers expressed during different stages of the cancer. We earlier reported the purification of a mitogenic lectin from human pathogenic fungus Cephalosporium curvulum (CSL) that has complex sugar specificity when analysed by hapten inhibition assay. In the present study, we report the fine sugar specificity of CSL as determined by glycan array analysis. The results revealed that CSL has exquisite specificity towards core fucosylated N-glycans. Fucosylated trimannosyl core is the basic structure required for the binding of CSL. The presence of fucose in the side chain further enhances the avidity of CSL towards such glycans. The affinity of CSL is drastically reduced towards the non-core fucosylated glycans, in spite of their side chain fucosylation. CSL showed no binding to the tested O-glycans and monosaccharides. These observations suggest the unique specificity of CSL towards core fucosylated N-glycans, which was further validated by binding of CSL to human colon cancer epithelial and hepatocarcinoma cell lines namely HT29 and HepG2, respectively, that are known to express core fucosylated N-glycans, using AOL and LCA as positive controls. LCA and AOL are fucose specific lectins that are currently being used clinically for the diagnosis of hepatocellular carcinomas. Most of the gastrointestinal markers express core fucosylated N-glycans. The high affinity and exclusive specificity of CSL towards α1-6 linkage of core fucosylated glycans compared to other fucose specific lectins, makes it a promising molecule that needs to be further explored for its application in the diagnosis of gastrointestinal cancer.
凝集素是一类碳水化合物结合蛋白，作为鉴定癌症不同阶段表达的特定聚糖标志物的重要工具，正受到广泛关注。我们之前报道了从人类致病真菌弯孢头孢霉中纯化出一种促有丝分裂凝集素（CSL），通过半抗原抑制试验分析发现其具有复杂的糖特异性。在本研究中，我们报告了通过聚糖阵列分析确定的CSL的精细糖特异性。结果显示，CSL对核心岩藻糖基化的N -聚糖具有极高的特异性。岩藻糖基化的三聚甘露糖核心是CSL结合所需的基本结构。侧链中岩藻糖的存在进一步增强了CSL对此类聚糖的亲和力。尽管非核心岩藻糖基化聚糖的侧链有岩藻糖基化，但CSL对其亲和力大幅降低。CSL对测试的O -聚糖和单糖无结合作用。这些观察结果表明CSL对核心岩藻糖基化N -聚糖具有独特的特异性，通过分别使用AOL和LCA作为阳性对照，CSL与已知表达核心岩藻糖基化N -聚糖的人结肠癌上皮细胞系HT29和肝癌细胞系HepG2的结合进一步验证了这一点。LCA和AOL是岩藻糖特异性凝集素，目前临床上用于肝细胞癌的诊断。大多数胃肠道标志物表达核心岩藻糖基化的N -聚糖。与其他岩藻糖特异性凝集素相比，CSL对核心岩藻糖基化聚糖的α1 - 6键具有高亲和力和独特特异性，这使其成为一个有前景的分子，需要进一步探索其在胃肠道癌诊断中的应用。
