Bisecting GlcNAc modification diminishes the pro‐metastatic functions of small extracellular vesicles from breast cancer cells

Abstract

Small extracellular vesicles (sEVs) are enriched in glycoconjugates and display specific glycosignatures. Aberrant expression of surface glycoconjugates is closely correlated with cancer progression and metastasis. The essential functions of glycoconjugates in sEVs are poorly understood. In this study, we observed significantly reduced levels of bisecting GlcNAc in breast cancer. Introduction of bisecting GlcNAc into breast cancer cells altered the bisecting GlcNAc status on sEVs, and sEVs with diverse bisecting GlcNAc showed differing functions on recipient cells. Carcinogenesis and metastasis of recipient cells were enhanced by sEVs with low bisecting GlcNAc, and the pro‐metastatic functions of sEVs was diminished by high bisecting GlcNAc modification. We further identified vesicular integrin β1 as a target protein bearing bisecting GlcNAc. Metastasis of recipient cells was strongly suppressed by high bisecting GlcNAc levels on vesicular β1. Our findings demonstrate the important roles of glycoconjugates on sEVs. Modification of sEV glycosylation may contribute to development of novel targets in breast cancer therapy.

Role of Site-Specific Glycosylation in the I-Like Domain of Integrin β1 in Small Extracellular Vesicle-Mediated Malignant Behavior and FAK Activation

“…Notably, N-glycosylation in the I-like and membrane-proximal domains of integrin β1 is critical for integrin-mediated functions [14,23]. Integrin β1 is reported to regulate the migratory ability of recipient cells via sEVs [1,7]. We hypothesized that site-specific N-glycosylation could modulate behaviors of recipient cells via transfer of vesicular integrin β1.…”

“…Previous study revealed that sEVs in soluble compounds from MDA-MB-231 cells enhance the migratory ability of MCF7 cells by addition of GW4869, an N-sMase2 inhibitor that blocks ceramide-mediated release of sEVs [1]. Integrin β1 was documented to be present on sEVs and transferred to recipient cells, resulting in enhanced cell migration [1,20], suggesting that integrin β1 might affect the cell migration and adhesion of recipient cells via sEVs. Given the important role of N-glycosylation in the I-like domain of integrin β1, we focused on the ∆4-6 mutant in the subsequent experiments.…”

“…Previous study revealed the biological function of N-glycosylation in different domains of integrin β1 [13,14]. Our recent study revealed that the migration ability of recipient cells was suppressed by vesicular integrin β1 with high levels of bisecting GlcNAc modification [1]. However, the effect of N-glycosylation in different domains of integrin β1 on biological function of sEVs is not well elucidated.…”

“…Small extracellular vesicles (sEVs), one type of membrane-covered structure (diameter 30-100 nm), originate from the endosomal pathway, are secreted by exocytosis into the surrounding extracellular space, and are present in various body fluids [1,2]. sEVs carry plentiful bioactive materials, including proteins, nuclear acids, and lipids, which mediate various types of cell-to-cell communication [3].…”

“…Recent studies have documented that vesicular epidermal growth factor receptor (vEGFR) from gastric cancer cells would be transferred into liver stromal cells, reprogramming the liver microenvironment and promoting cancer cells' liver-targeted metastasis [6]. Several studies have confirmed the intercellular transfer of integrin by sEVs to modulate the physiology of recipient cells [1,7]. For example, vesicular integrins determine the organ-specific metastasis of derived tumor cells, and blockage of integrin binding with extracellular matrix (ECM) was found to decrease sEV uptake and tumor metastasis [7].…”