This alters cholesterol homeostasis in HCC, increasing 27HC levels, which leads to increased GPX4 and protects cells from ferroptosis in HCC cells; furthermore, it can also be discharged into the TME, activating the PPAR/CPTA1 pathway, causing lipid accumulation in macrophages, resulting in TAM metabolic reprogramming, and consequently promoting M2 polarization. The gene discussed is PPARA; the disease is hepatocellular carcinoma.