B7-H6 promotes the killing activity of NK cells against cervical cancer through the downstream ERK pathway of NKp30

Abstract

OBJECTIVE As a ligand of NKp30, B7 homolog 6 (B7-H6) is involved in the immune regulation of various tumors. The aim of this study was to clarify the effect of B7-H6 expressed in HeLa cells on NK cell killing function. METHODS The expression of B7H6 was changed in HeLa cells using short hairpin RNA. Furthermore the effect of B7-H6 on the killing function of NK cell was analyzed after cell co-culture. Flow cytometry was used to detect NKp30 expression, degranulation function, perforin (PFP) and Granzyme B (GZMB) secretion function of NK cells. Enzyme-linked immunosorbent assay (ELISA) was used to detect interferon-γ (INF-γ) production function. The cytotoxicity of NK-92 cells was determined using the CytoTox 96 Non-Radio active Cytotoxicity Assay. Western blotting (WB) detection was used to detect the ERK phosphorylation level in NK cells. RESULTS When NK-92 cells co-cultivated with HeLa cells with different expression levels of B7-H6, the expression of NKp30, NK-92 cell killing rate, PFP and INF-γ production, and degranulation function were correspondingly changed in NK cells, but there is no effcet on GZMB production. After cell co-culture, ERK phosphorylation level in NK cells was increased gradually with the up-regulation of B7-H6 expression. CONCLUSIONS B7-H6 can enhance the killing function of NK cells to HeLa cells by activating the NKp30 downstream ERK signaling pathway.