ZDHHC16-induced GPX2 S-palmitoylation promotes lenvatinib resistance and inhibits lenvatinib-induced immunogenic cell death in hepatocellular carcinoma.

S-palmitoylation is a common and reversible post-translational modification. This study aims to elucidate the functional role and mechanism of S-palmitoylation in lenvatinib resistance and lenvatinib-induced immunogenic cell death (ICD) in hepatocellular carcinoma (HCC). Using small interfering RNA (siRNA) screening in HCC cells, zinc finger DHHC-type palmitoyltransferase 16 (ZDHHC16) was identified as a lenvatinib resistance-associated palmitoyl acyltransferase. ZDHHC16 was abnormally overexpressed in both lenvatinib-resistant tissues and cells. ZDHHC16 knockdown improved the sensitivity of HCC cells to lenvatinib. Furthermore, ZDHHC16 knockdown boosted lenvatinib-induced ICD of HCC cells, characterized by an increase in the release of danger associated molecular patterns (DAMPs), including calreticulin (CRT) exposure on the tumor cell surface, high mobility group box 1 (HMGB1), annexin A1 (ANXA1), and adenosine-5'-triphosphate (ATP), as well as an increase in reactive oxygen species (ROS) production, endoplasmic reticulum (ER) stress, and the secretion of cytotoxic cytokines (tumor necrosis factor (TNF)-α and interferon (IFN)-γ). Mechanistically, ZDHHC16 catalyzed the S-palmitoylation of glutathione peroxidase 2 (GPX2) at C67, which prevented ubiquitination-proteasome degradation of GPX2, thereby enhancing its protein stability. Targeting the ZDHHC16-mediated GPX2 S-palmitoylation improved lenvatinib-induced ICD and antitumor immunity, thereby enhancing the efficacy of lenvatinib. Collectively, our findings reveal that ZDHHC16-induced GPX2 S-palmitoylation plays a crucial role in modulating lenvatinib resistance and lenvatinib-induced ICD in HCC. Targeting this pathway is a promising approach to improve lenvatinib's antitumor activity.