Dual Targeting of EZH2 and LSD1 Suppresses Hepatocellular Carcinoma via Disruption of Sonic Hedgehog Signaling

Hepatocellular carcinoma (HCC) is a highly aggressive malignancy with poor prognosis and limited therapeutic options. Although epigenetic dysregulation is a hallmark of HCC, rational combinatorial targeting strategies remain incompletely defined. Here, we identify cooperative oncogenic functions of the chromatin modifiers enhancer of zeste homolog 2 (EZH2) and lysine-specific demethylase 1 (LSD1) in HCC. Analysis of the TCGA-LIHC cohort revealed that co-elevated EZH2 and LSD1 expressions are significantly associated with reduced overall survival. Gene set enrichment analysis demonstrated enrichment of Sonic Hedgehog (SHH) signaling and stress-responsive transcriptional programs in tumors with high EZH2/LSD1 expression. Functionally, dual pharmacological inhibition of EZH2 (GSK126) and LSD1 (SP2509) suppressed HCC cell proliferation, induced G1-phase arrest, and enhanced apoptosis, as evidenced by increased caspase-3/7 activity and decreased pro-caspase levels. Dual inhibition also impaired migration, invasion, tumor sphere formation, and stemness-associated gene expression. Mechanistically, co-targeting disrupted SHH signaling through the suppression of GLI1 expression. Chromatin immunoprecipitation revealed reduced EZH2, LSD1, and STAT3 occupancy at the GLI1 promoter following dual inhibition, leading to the repression of GLI1 and its downstream targets. Collectively, these findings demonstrate that EZH2 and LSD1 cooperatively sustain GLI1-dependent SHH signaling in HCC, and that dual epigenetic inhibition represents a mechanistically defined therapeutic strategy.