The effect of CMTM6 on the anti-HCC efficacy of iNKT cells via stabilizing PD-L1 in an experimental investigation

Abstract

Abstract Background CMTM6 is a key regulator of PD-L1. The purpose of this study is to see whether CMTM6 impacts iNKT cells infiltration into hepatocellular carcinoma (HCC) and whether CMTM6 knockout promotes iNKT cells activation via the PD-1/PD-L1 signaling axis, hence impacting anti-HCC efficacy. Methods Immunohistochemistry and multiplex fluorescence immunohistochemistry were conducted to evaluate the expression of CMTM6, PD-1, PD-L1, and iNKT (CD3+CD56+) cells. Flow cytometry (FCM), enzyme-linked immunosorbent assay (ELISA), cell proliferation, killing, colony formation assay, and wound healing assay were applied to investigate the effect of CMTM6 knockout on the anti-HCC efficacy of iNKT cells. Results In HCC tumor tissues, there's far more CMTM6, PD-L1, and PD-1 expression. PD-L1 and PD-1 were both positively associated with CMTM6. iNKT cells infiltration was reduced, whereas PD-1 expression was increased. Infiltration of iNKT cells was reduced by increased CMTM6 expression. CMTM6 knockout inhibited the proliferation, invasion, and migration of HepG2 cells by downregulating the PD-1/PD-L1 signaling axis and promoting the secretion of IFN-γ, Perforin, and Granzyme B of iNKT cells, boosting their killing effect, and inhibiting the proliferation, invasion, and migration of HepG2 cells. Conclusions Our findings showed that CMTM6 was more abundant in HCC tumor tissues than adjacent tissues. Knocking out CMTM6 could boost iNKT cells activation and improve anti-HCC efficacy by blocking the PD-1/PD-L1 signaling axis, which may serve as a potential therapeutic target for HCC