Integrin α6‐containing extracellular vesicles promote lymphatic remodelling for pre‐metastatic niche formation in lymph nodes via interplay with CD151

Abstract

Abstract Heterogeneous extracellular vesicles (EVs) from various types of tumours are acknowledged for inducing the formation of pre‐metastatic “niches” in draining lymph nodes (LNs) to promote lymphatic metastasis. In order to identify the specific subpopulations of EVs involved, we performed high‐resolution proteomic analysis combined with nanoflow cytometry of bladder cancer (BCa) tissue‐derived EVs to identify a novel subset of tumour‐derived EVs that contain integrin α6 (ITGA6+EVs) and revealed the positive correlation of ITGA6+EVs with the formation of pre‐metastatic niche in draining LNs and lymphatic metastasis in multicentre clinical analysis of 820‐case BCa patients. BCa‐derived ITGA6+EVs induced E‐selectin (SELE)‐marked lymphatic remodelling pre‐metastatic niche and promoted metastasis in draining LNs through delivering cargo circRNA‐LIPAR to lymphatic endothelial cells in vivo and in vitro. Mechanistically, LIPAR linked ITGA6 to the switch II domain of RAB5A and sustained RAB5A GTP‐bound activated state, thus maintaining the production of ITGA6+EVs loaded with LIPAR through endosomal trafficking. ITGA6+EVs targeted lymphatic vessels through ITGA6‐CD151 interplay and released LIPAR to induce SELE overexpression‐marked lymphatic remodelling pre‐metastatic niche. Importantly, we constructed engineered‐ITGA6 EVs to inhibit lymphatic pre‐metastatic niche, which suppressed lymphatic metastasis and prolonged survival in preclinical models. Collectively, our study uncovers the mechanism of BCa‐derived ITGA6+EVs mediating pre‐metastatic niche and provides an engineered‐EV‐based strategy against BCa lymphatic metastasis.

Keywords

• bladder cancer
• extracellular vesicles
• ITGA6
• lymphatic metastasis
• pre‐metastatic niche