Abstract
Protein S-palmitoylation, a dynamic and reversible post-translational modification involving the attachment of palmitate to cysteine residues, is a key regulator of protein functionality and cellular signalling. Dysregulation of this modification has emerged as a critical driver of cancer progression. Among the 23 DHHC palmitoyl transferases responsible for catalysing S-palmitoylation, aberrant expression of specific members is linked to tumorigenesis and development, underscoring their potential as promising therapeutic targets. However, the cancer-specific roles and substrates of individual DHHC enzymes remain poorly characterised. In this study, we identified DHHC9 as a crucial regulator of adenocarcinoma progression, including colorectal and lung cancers. Functional studies demonstrated that DHHC9 knockdown profoundly inhibited cell migration in vitro and tumour metastasis in vivo. Proteomic and functional analyses revealed that STRN4, a core component of the STRIPAK complex, was palmitoylated by DHHC9 at cysteine 701. The STRN4 palmitoylation reduced YAP phosphorylation, promoted nuclear translocation of YAP and activated downstream Hippo pathway transcriptional targets-including CCN1, CCN2 and ANKRD1-thereby driving cancer cell migration. Notably, we discovered two small molecules, Treprostinil and 10-HCPT, as potent DHHC9 inhibitors that effectively suppressed adenocarcinoma cell migration. Our findings define the DHHC9-STRN4-YAP axis as a novel mechanism linking palmitoylation to phosphatase regulation and Hippo pathway dysregulation, unveiling DHHC9 as a highly promising therapeutic target in cancer treatment.