Phenethyl Isothiocyanate Suppresses Hepatocellular Carcinoma Progression and Immune Evasion via ZNF652 Regulation of PD-L1.

The therapeutic efficacy of immune checkpoint inhibitors in hepatocellular carcinoma (HCC) remains limited, with programmed death receptor-1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) blockade effective in only some patients. Here, we report that phenethyl isothiocyanate (PEITC), a bioactive phytochemical, demonstrated promising anticancer potential in HCC by inhibiting cell proliferation and migration, while promoting apoptosis in vitro. We also observed that PEITC significantly suppressed tumorigenesis of HCC in vivo. Importantly, PEITC downregulated PD-L1 expression in a concentration-dependent manner and enhanced the sensitivity of HCC cells to T cell-mediated cytotoxicity. When combined with anti-PD-L1 antibody, PEITC improved the efficacy of immunotherapy. Additionally, bioinformatics and experimental validation revealed that zinc finger protein 652 (ZNF652), a transcription factor, was upregulated and positively correlated with PD-L1 expression in HCC. Mechanistically, ZNF652 bound to the promoter of PD-L1 to activate its transcription. ZNF652 overexpression partially reversed the suppressive effects of PEITC on PD-L1 expression and T cell cytotoxicity, while ZNF652 knockdown enhanced these effects in vitro. These findings indicated that PEITC suppresses HCC progression and immune evasion by downregulating PD-L1 via modulation of ZNF652, providing a basis for its potential use in HCC immunotherapy.