Hirata Tetsuya, Harada Yoichiro, Hirosawa Koichiro M, Tokoro Yuko, Suzuki Kenichi G N, Kizuka Yasuhiko
Laboratory of Glyco-biochemistry, Institute for Glyco-core Research (iGCORE), Gifu University, Gifu 501-1193, Japan.
Department of Glyco-Oncology and Medical Biochemistry, Osaka International Cancer Institute, Osaka 541-8567, Japan.
iScience. 2022 Dec 6;26(1):105747. doi: 10.1016/j.isci.2022.105747. eCollection 2023 Jan 20.
Small extracellular vesicles (sEVs) secreted from cancer cells play pivotal roles in cancer metastasis and malignancy by transferring biomolecules and conditioning future metastatic sites. Studies have elucidated structures and functions of glycans on sEVs; however, whether sEVs remodel glycans in recipient cells remains poorly understood. Here, we examined the enzyme activity of glycosyltransferases for complex -glycan biosynthesis in cancer-derived sEVs and discovered that cancer-related glycosyltransferase, -acetylglucosaminyltransferase-V (GnT-V, a.k.a. MGAT5), is selectively enriched in sEVs among various glycosyltransferases. GnT-V in sEVs is a cleaved form, and cleavage by SPPL3 protease is necessary for loading GnT-V in sEVs. Fractionation experiments and single-particle imaging further revealed that GnT-V was enriched in non-exosomal sEVs. Strikingly, we found that enzymatically active GnT-V in sEVs was transferred to recipient cells and the -glycan structures of recipient cells were remodeled to express GnT-V-produced glycans. Our results suggest GnT-V-enriched sEVs' role in glycan remodeling in cancer metastasis.
癌细胞分泌的小细胞外囊泡（sEVs）通过传递生物分子和调节未来的转移位点，在癌症转移和恶性肿瘤中发挥关键作用。研究已经阐明了sEVs上聚糖的结构和功能；然而，sEVs是否会重塑受体细胞中的聚糖仍知之甚少。在这里，我们检测了癌症来源的sEVs中用于合成复合聚糖的糖基转移酶的酶活性，发现与癌症相关的糖基转移酶——N-乙酰葡糖胺基转移酶-V（GnT-V，又名MGAT5）在各种糖基转移酶中选择性地富集于sEVs中。sEVs中的GnT-V是一种裂解形式，SPPL3蛋白酶的裂解是将GnT-V装载到sEVs中所必需的。分级分离实验和单颗粒成像进一步表明，GnT-V在非外泌体sEVs中富集。引人注目的是，我们发现sEVs中具有酶活性的GnT-V被转移到受体细胞中，并且受体细胞的N-聚糖结构被重塑以表达GnT-V产生的聚糖。我们的结果表明，富含GnT-V的sEVs在癌症转移中的聚糖重塑中发挥作用。
