SEVs-carried ENPP1 regulates DCs' activation and inhibits the formation of tertiary lymphoid structures in gastric cancer.

BACKGROUND

Ectonucleotide pyrophosphatase/phosphodiesterase 1(ENPP1) is a potential immune checkpoint, but the role and mechanism of small extracellular vesicles (sEVs)-carried ENPP1 in the formation of tertiary lymphoid structures (TLS) in gastric cancer (GC) are still unclear.

METHODS

GEO database, prognostic analysis, immune and single-cell analysis were used to explore the potential role of ENPP1 in GC. Electron microscopy, nanoparticle-tracking analysis identification and WB detection of marker proteins were used to verify the sEVs. Immunohistochemical staining, immunofluorescence staining, cell co-culture and flow cytometry were used to investigate the relationship among GC-derived sEVs-carried ENPP1 and dendritic cells (DCs) activation and TLS formation. Mice xenograft tumor model was used to explore the influence of sEVs-carried ENPP1 on vivo changes.

RESULTS

ENPP1 was highly expressed in GC tissues and cell lines and was associated with immune regulation. Immunohistochemistry showed that sEVs-carried ENPP1 expression was negatively correlated with the infiltration of DCs and CD8+ T cells and the number of TLS in GC. Co-culture experiment showed that sEVs-carried ENPP1 could hydrolyze 2'3'-cGAMP and could be taken up by DCs. Inhibiting sEVs-carried ENPP1 expression promoted DCs' activation. Inhibition of sEVs-carried ENPP1 expression reduced the growth volume and weight of transplanted tumors in 615 mice, while increasing the activation of DCs, CD8+ T cells, TLS and the formation of high endothelial venules.

CONCLUSIONS

SEVs-carried ENPP1 regulates DCs' activation to inhibit TLS formation in GC. Our study illumes a new interaction mechanism between tumor cells and the immune microenvironment in GC.