Pancreatic cancer-derived small extracellular vesical Ezrin regulates macrophage polarization and promotes metastasis

Small extracellular vesicles (sEVs) mediate the interaction between tumor and tumor-associated macrophages (TAMs). This study aims to demonstrate that the pancreatic ductal adenocarcinoma (PDAC)-derived sEV Ezrin (sEV-EZR) could modulate macrophage polarization and promote PDAC metastasis. We isolated PDAC-derived sEVs and plasma sEVs from PDAC patients. Human blood mononuclear cell (PBMC)-derived macrophages were treated with PDAC-derived sEVs or the counterpart depleted Ezrin (EZR) with shRNA-mediated knockdown. We used enzyme-linked immunosorbent assays and flow cytometry to monitor macrophages polarization. NOD/SCID/IL2Rγ^null mice were treated with sEVs to study PDAC liver metastasis. The plasma sEV-EZR levels of 165 PDAC patients and 151 high-risk controls were analyzed. The EZR levels are higher in sEVs derived from PDAC cells and PDAC-patient plasma than that of the normal controls. PDAC-derived sEVs modulate the polarization of macrophages to M2 phenotype, while PDAC-shEZR-derived sEVs polarize macrophages into M1 phenotype. We found an increase in M1 TAMs and a decrease in M2 TAMs in orthotropic tumors treated with PDAC-shEZR-derived sEVs. The amount of liver metastasis in PDAC-shEZR-derived sEVs-treated mice was observed to be smaller than that of controls. The mean plasma sEV-EZR levels from PDAC patients were significantly higher than those from the controls (32.43±20.78 vs. 21.88±11.43 pg/ml; P<0.0001). The overall survival in the high-plasma sEV-EZR patients was significantly shorter than that in the low-EZR group (6.94±15.25 vs. 9.63±15.11 months; P=0.0418). sEV-EZR could modulate macrophage polarization and promote metastasis in PDAC. Targeting sEV-EZR can be considered a promising therapeutic strategy to inhibit PDAC metastasis.