Laboratory of Glycobiology, The Noguchi Institute, 1-9-7, Kaga, Itabashi, Tokyo 173-0003, Japan.
Laboratory of Glyco-organic Chemistry, The Noguchi Institute, 1-9-7, Kaga, Itabashi, Tokyo 173-0003, Japan.
Glycobiology. 2024 Aug 30;34(10). doi: 10.1093/glycob/cwae064.
Peritoneal metastasis frequently accompanies metastatic and/or recurrent gastric cancer, leading to a poor prognosis owing to a lack of effective treatment. Hence, there is a pressing need to enhance our understanding of the mechanisms and molecules driving peritoneal metastasis. In a previous study, galectin-4 inhibition impeded peritoneal metastasis in a murine model. This study examined the glycan profiles of cell surface proteins and glycosphingolipids (GSLs) in cells with varying tumorigenic potentials to understand the intricate mechanisms underlying galectin-4-mediated regulation, particularly glycosylation. Detailed mass spectrometry analysis showed that galectin-4 knockout cells exhibit increased expression of lacto-series GSLs with β1,3-linked galactose while showing no significant alterations in neolacto-series GSLs. We conducted real-time polymerase chain reaction (PCR) analysis to identify candidate glycosyltransferases that synthesize increased levels of GSLs. Subsequently, we introduced the candidate B3GALT5 gene and selected the clones with high expression levels. B3GALT5 gene-expressing clones showed GSL glycan profiles like those of knockout cells and significantly reduced tumorigenic ability in mouse models. These clones exhibited diminished proliferative capacity and showed reduced expression of galectin-4 and activated AKT. Moreover, co-localization of galectin-4 with flotillin-2 (a raft marker) decreased in B3GALT5-expressing cells, implicating GSLs in galectin-4 localization to lipid rafts. D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (a GSL synthase inhibitor) also affected galectin-4 localization in rafts, suggesting the involvement of GSL microdomains. We discovered that B3GALT5 plays a crucial role in regulating peritoneal metastasis of malignant gastric cancer cells by suppressing cell proliferation and modulating lipid rafts and galectin-4 via mechanisms that are yet to be elucidated.
腹膜转移常伴有转移性和/或复发性胃癌，由于缺乏有效治疗方法，预后较差。因此，迫切需要提高我们对驱动腹膜转移的机制和分子的理解。在之前的研究中，半乳糖凝集素-4 抑制可阻止小鼠模型中的腹膜转移。本研究检查了具有不同致瘤潜力的细胞表面蛋白和糖脂（GSL）的聚糖谱，以了解半乳糖凝集素-4 介导的调节的复杂机制，特别是糖基化。详细的质谱分析表明，半乳糖凝集素-4 敲除细胞表现出增加的具有β1,3-连接的半乳糖的乳酰系列 GSL 的表达，而在新乳糖系列 GSL 中没有明显变化。我们进行了实时聚合酶链反应（PCR）分析，以鉴定合成增加水平 GSL 的候选糖基转移酶。随后，我们引入了候选 B3GALT5 基因，并选择了高表达水平的克隆。B3GALT5 基因表达克隆表现出与敲除细胞相似的 GSL 聚糖谱，并显著降低了小鼠模型中的致瘤能力。这些克隆表现出增殖能力降低，并显示出半乳糖凝集素-4 表达减少和 AKT 激活减少。此外，B3GALT5 表达细胞中半乳糖凝集素-4 与 flotillin-2（筏标记物）的共定位减少，表明 GSL 参与半乳糖凝集素-4 向脂质筏的定位。D-threo-1-苯基-2-癸酰氨基-3-吗啉-1-丙烷（一种 GSL 合酶抑制剂）也影响了筏中的半乳糖凝集素-4 定位，表明 GSL 微区的参与。我们发现 B3GALT5 通过抑制细胞增殖以及通过尚待阐明的机制调节脂质筏和半乳糖凝集素-4，在恶性胃癌细胞的腹膜转移中发挥关键作用。
