Small Extracellular Vesicle-TLN1 Modulates Gastric Cancer Cells and Remodels Lymphatic Endothelial Cells Through AKT Activation to Potentiate Lymphatic Metastasis.

Lymph node metastasis is a pivotal determinant of poor prognosis of gastric cancer, but the molecular orchestrators of lymphatic dissemination remain poorly characterized. Recent research highlights the pivotal role of small extracellular vesicles (sEVs) with specific cargo during the process. Herein, TLN1 was identified as being selectively enriched within sEVs from highly lymph-metastatic gastric cancer cells and in the serum of gastric cancer patients with lymph node metastasis, as identified through proteomic screening and confirmed by western blotting. sEVs act as key autocrine signals that influence gastric cancer cell behaviors such as proliferation, migration, invasion, and adhesion. TLN1 protein levels in cells correlate with their lymphatic metastatic potential and determine TLN1 content in sEVs. Inhibiting TLN1 reduces these cancer cell malignant behaviors and leads to TLN1-depleted sEVs. TLN1 could be transferred to gastric cancer cells and human lymphatic endothelial cells (HLECs) via sEVs. Without TLN1, sEVs cannot enhance cancer cell malignancy or induce HLEC proliferation, tube formation, adhesion, permeability in vitro, or lymphatic metastasis in vivo. Mechanistically, AKT activation was identified as a mediator of the effects exerted by sEV-TLN1 on both gastric cancer cells and HLECs. In conclusion, TLN1 orchestrates lymphatic metastasis in gastric cancer by dual-modulating tumor cell malignancy and lymphatic vessel remodeling via AKT activation. This discovery offers new perspectives on the mechanisms driving lymphatic metastasis in gastric cancer and proposes a promising target for the detection and therapeutic intervention of lymph node metastasis.