Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Provincial Key Laboratory of Biotechnology, College of Life Sciences, Northwest University, 229 Taibai North Road, Xi'an, 710069, People's Republic of China.
Department of Urology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, People's Republic of China.
Angiogenesis. 2024 Nov;27(4):883-901. doi: 10.1007/s10456-024-09947-3. Epub 2024 Sep 2.
The permeability of blood vessels plays a crucial role in the spread of cancer cells, facilitating their metastasis at distant sites. Small extracellular vesicles (sEVs) are known to contribute to the metastasis of various cancers by crossing the blood vessel wall. However, the role of abnormal glycoconjugates on sEVs in tumor blood vessels remains unclear. Our study found elevated levels of fucosyltransferase VII (FUT7) and its product sialyl Lewis X (sLeX) in muscle-invasive bladder cancer (BLCA), with high levels of sLeX promoting the growth and invasion of BLCA cells. Further investigation revealed that sLeX was enriched in sEVs derived from BLCA. sLeX-decorated sEVs increased blood vessel permeability by disrupting the tight junctions of human umbilical vein endothelial cells (HUVECs). Using the glycoproteomics approach, we identified integrin α3 (ITGA3) as a sLeX-bearing glycoprotein in BLCA cells and their sEVs. Mechanically, sLeX modification stabilized ITGA3 by preventing its degradation in lysosomes. sEVs carrying sLeX-modified ITGA3 can be effectively internalized by HUVECs, leading to a decrease in the expression of tight junction protein. Conversely, silencing ITGA3 in sLeX-decorated sEVs restored tight junction proteins and reduced blood vessel permeability by inhibiting the MAPK pathway. Moreover, sLeX-modification of ITGA3 at Asn 265 in HUVECs promoted occludin dephosphorylation at Ser/Thr residues, followed by inducing its importin α1-mediated nuclear translocation, which resulted in the disruption of tight junctions. Our findings suggest a potential strategy for disrupting the formation of a metastatic microenvironment and preventing the spread of malignant bladder cancer.
血管通透性在癌细胞的扩散中起着至关重要的作用，促进其在远处部位转移。已知小细胞外囊泡（sEVs）通过穿过血管壁有助于各种癌症的转移。然而，异常糖缀合物在肿瘤血管中的 sEVs 中的作用仍不清楚。我们的研究发现，在肌肉浸润性膀胱癌（BLCA）中，岩藻糖基转移酶 VII（FUT7）及其产物唾液酸化路易斯 X（sLeX）水平升高，高水平的 sLeX 促进 BLCA 细胞的生长和侵袭。进一步的研究表明，sLeX 在源自 BLCA 的 sEVs 中富集。sLeX 修饰的 sEVs 通过破坏人脐静脉内皮细胞（HUVEC）的紧密连接来增加血管通透性。使用糖蛋白质组学方法，我们鉴定出整合素 α3（ITGA3）作为 BLCA 细胞及其 sEVs 中带有 sLeX 的糖蛋白。在机制上，sLeX 修饰通过防止溶酶体降解来稳定 ITGA3。携带 sLeX 修饰的 ITGA3 的 sEVs 可被 HUVEC 有效内化，导致紧密连接蛋白表达减少。相反，在 sLeX 修饰的 sEVs 中沉默 ITGA3 通过抑制 MAPK 途径恢复紧密连接蛋白并降低血管通透性。此外，HUVECs 中 ITGA3 的 Asn 265 上的 sLeX 修饰促进了封闭蛋白在 Ser/Thr 残基上的去磷酸化，随后诱导其导入蛋白 α1 介导的核转位，导致紧密连接的破坏。我们的研究结果表明了一种破坏转移微环境形成和防止恶性膀胱癌扩散的潜在策略。
