Inohara H, Akahani S, Koths K, Raz A
Tumor Progression and Metastasis Program, Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA.
Cancer Res. 1996 Oct 1;56(19):4530-4.
Galectin-3 is a beta-galactoside-specific lectin implicated in diverse processes involved in cellular interactions. Recently, the Mac-2-binding protein, a heavily N-glycosylated secreted protein with a subunit Mr of 97,000, was identified as its ligand. The present study characterizes the interaction between galectin-3 and Mac-2-binding protein in whole cells and measures their relative expression levels. Incubation of A375 cells with affinity-purified Mac-2-binding protein resulted in its binding to galectin-3 on the cell surface in a specific carbohydrate-dependent manner. Mac-2-binding protein also induced homotypic cell aggregation, which was inhibited by lactose or Fab' fragments of an anti-galectin-3 antibody. Northern blotting analysis revealed differences in the transcriptional regulation of galectin-3 and Mac-2-binding protein. These results provide the first direct evidence for a Mac-2-binding protein function and suggest that it may play a role in tumor cell embolization during metastasis through interaction with galectin-3.
半乳糖凝集素-3是一种β-半乳糖苷特异性凝集素，参与细胞间相互作用的多种过程。最近，Mac-2结合蛋白被鉴定为其配体，该蛋白是一种高度N-糖基化的分泌蛋白，亚基分子量为97,000。本研究表征了全细胞中半乳糖凝集素-3与Mac-2结合蛋白之间的相互作用，并测定了它们的相对表达水平。用亲和纯化的Mac-2结合蛋白孵育A375细胞，导致其以特定的碳水化合物依赖性方式与细胞表面的半乳糖凝集素-3结合。Mac-2结合蛋白还诱导同型细胞聚集，这被乳糖或抗半乳糖凝集素-3抗体的Fab'片段所抑制。Northern印迹分析揭示了半乳糖凝集素-3和Mac-2结合蛋白转录调控的差异。这些结果为Mac-2结合蛋白的功能提供了首个直接证据，并表明它可能通过与半乳糖凝集素-3相互作用在转移过程中的肿瘤细胞栓塞中发挥作用。
