Hepatoblastoma‐Derived Exosomal <scp>FASN</scp> Affected the Differentiation of Hepatic Stellate Cells Into Cancer‐Associated Fibroblasts by Regulating the Stability of <scp>HK2</scp> and Mediating Histone Lactylation

Cancer-associated fibroblasts (CAFs) interact with tumor cells in the tumor microenvironment (TME), enhancing glycolysis in CAFs and tumor malignancy. However, the regulatory mechanisms between hepatoblastoma (HB) cells and CAFs are unclear. This study aimed to elucidate the crosstalk mechanism between HB cells and CAFs and identify a new therapeutic target for HB. Exosomes were successfully extracted from Huh-6/HepG2 cells, and hepatic stellate cells (LX2) were treated with conditioned medium or exosomes from these cells. We found that HB cells may stimulate the differentiation of LX2 cells into CAFs through exosomes and enhance histone lactylation. Additionally, HB cell exosome-derived fatty acid synthase (FASN) promoted the transformation of LX2 cells into CAFs and histone lactylation. Mechanistically, FASN affected the transformation of LX2 cells into CAFs and histone lactylation by regulating hexokinase 2 (HK2). FASN regulated HK2 stability by competitively combining with MARCHF1. Activated fibroblasts promoted HB progression by secreting CXCL1/CXCL5. In vivo experiments have demonstrated that HB cell exosome-derived FASN affected the transformation of LX2 cells into CAFs and histone lactylation. Clinical sample analysis revealed that FASN protein expression was significantly positively correlated with the levels of HK2, lactate, and H3K18la, thereby validating the clinical relevance of this regulatory pathway. In conclusion, HB-derived exosomal FASN affected the transformation of LX2 cells into CAFs by regulating the stability of HK2 and mediating histone lactylation, providing novel insights into the crosstalk between HB cells and CAFs and highlighting exosomal FASN as a potential therapeutic target for HB.