Carcinoma-associated fibroblasts (CAFs) are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix (ECM). The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase (LOX). Small extracellular vesicles (sEVs) mediate cell-cell communication. However, the interactions between sEVs and the ECM remain unclear. Here, we demonstrated that sEVs released from oral squamous cell carcinoma (OSCC)-derived CAFs induce collagen crosslinking, thereby promoting epithelial-mesenchymal transition (EMT). CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking, and a LOX inhibitor or blocking antibody suppressed this effect. Active LOX (αLOX), but not the LOX precursor, was enriched in CAF sEVs and interacted with periostin, fibronectin, and bone morphogenetic protein-1 on the surface of sEVs. CAF sEV-associated integrin α2β1 mediated the binding of CAF sEVs to collagen I, and blocking integrin α2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I. CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway. Taken together, these findings reveal a novel role of CAF sEVs in tumor ECM remodeling, suggesting a critical mechanism for CAF-induced EMT of cancer cells.

癌相关成纤维细胞（CAF）是肿瘤微环境的主要细胞成分，通过改变细胞外基质（ECM）促进癌症进展。肿瘤相关 ECM 的特点是赖氨酰氧化酶 (LOX) 催化的胶原交联。小细胞外囊泡 (sEV) 介导细胞间通讯。然而，sEV 和 ECM 之间的相互作用仍不清楚。在这里，我们证明口腔鳞状细胞癌（OSCC）衍生的 CAF 释放的 sEV 会诱导胶原交联，从而促进上皮间质转化（EMT）。CAF sEV 优先与 ECM 结合，而不是被成纤维细胞吸收并诱导胶原交联，而 LOX 抑制剂或封闭抗体可抑制这种效应。活性 LOX (αLOX)，而非 LOX 前体，在 CAF sEV 中富集，并与 sEV 表面的骨膜素、纤连蛋白和骨形态发生蛋白 1 相互作用。CAF sEV相关整合素α2β1介导CAF sEV与胶原蛋白I的结合，阻断整合素α2β1通过干扰CAF sEV与胶原蛋白I的结合来抑制胶原蛋白交联。CAF sEV诱导的胶原蛋白交联通过FAK/paxillin/YAP促进OSCC的EMT途径。总而言之，这些发现揭示了 CAF sEV 在肿瘤 ECM 重塑中的新作用，表明 CAF 诱导癌细胞 EMT 的关键机制。