ZDHHC3-mediated SCAP S-acylation promotes cholesterol biosynthesis and tumor immune escape in hepatocellular carcinoma

Cholesterol metabolism reprogramming plays essential roles in hepatocellular carcinoma (HCC). However, precisely how cholesterol metabolism is dysregulated is not clear. Here, we show that the palmitoyltransferase ZDHHC3 and depalmitoylase ABHD17A regulate HCC cell cholesterol biosynthesis by dynamically S-acylating SREBP cleavage-activating protein (SCAP). SCAP S-acylation by ZDHHC3 at C264 antagonizes HACE1-mediated SCAP ubiquitination. Intriguingly, SREBP2 transcriptionally upregulates ZDHHC3 to form a positive feedback loop, which explains why negative feedback regulation of SCAP/SREBP2 signaling fails in HCC. Increased cholesterol in the tumor microenvironment (TME) restrains CD4