LDN-57444 sensitizes hepatocellular carcinoma cells to sorafenib by promoting ferroptosis through histone deacetylase 2 (HDAC2) inhibition.

BACKGROUND: Hepatocellular carcinoma (HCC) is still one of the leading causes of cancer-related mortality worldwide. Sorafenib is commonly used as first-line systemic treatment for advanced HCC, but the clinical benefits fall victim to either primary or acquired drug resistance. Modulating ferroptosis, a form of iron-dependent regulated cell death (RCD), has been increasingly explored in order to circumvent this chemoresistance. METHODS: We performed a pharmacogenomic screening analysis using the DepMap database to identify small molecules whose cytotoxicity patterns resemble those of known ferroptosis inducers. Among the candidates, LDN-57444 was selected for further evaluation. Its ability to enhance the anticancer activity of sorafenib was examined in PLC/PRF/5 and Hep3B HCC cell lines using cell viability assays, molecular docking, cellular thermal shift assays (CETSA), and siRNA-mediated gene silencing. RESULTS: In the HCC models tested, sorafenib alone did not induce ferroptosis, unlike some earlier reports. LDN-57444, previously described as an inhibitor of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1), emerged as a strong ferroptosis sensitizer. Co-treatment with LDN-57444 and sorafenib led to pronounced synergistic cytotoxicity, and this effect was completely abolished by the ferroptosis inhibitor ferrostatin-1. Mechanistic analyses showed that the synergy is independent of UCH-L1. Structural modeling and target-engagement experiments indicated that histone deacetylase 2 (HDAC2) is the relevant molecular target. Silencing HDAC2, but not HDAC1, reduced sensitivity to the drug combination, supporting the idea that LDN-57444 enhances sorafenib activity by modulating HDAC2. CONCLUSION: Our findings demonstrate that LDN-57444 potentiates sorafenib-induced ferroptosis in HCC cells through an HDAC2-dependent mechanism. These results highlight the therapeutic potential of combining HDAC2 inhibitors with sorafenib to improve treatment responses in advanced HCC.