RRx-001 inhibits G6PD to deplete NADPH and trigger disulfidptosis coupled with DAMP-mediated immunogenic cell death in hepatocellular carcinoma

Abstract

Disulfidptosis is a recently identified form of programmed cell death driven by NADPH metabolic imbalance and disulfide stress, but its therapeutic relevance in hepatocellular carcinoma (HCC) remains poorly understood. RRx-001, a clinical-stage small-molecule agent known for its epigenetic modulatory and radiosensitizing effects, has yet to be explored for its potential to induce disulfidptosis and immunogenic cell death (ICD). This study investigated the mechanism by which RRx-001 triggers disulfidptosis in HCC through NADPH metabolic dysregulation and evaluated its capacity to elicit ICD and antitumor immunity. Using Huh-7 and Hepa1-6 HCC cell lines and a murine subcutaneous xenograft model, we assessed drug sensitivity (CCK-8), apoptosis (flow cytometry), metabolic parameters (NADPH, GSH/GSSG, ROS), and ultrastructural changes (transmission electron microscopy). Protein expression was analyzed by immunofluorescence and Western blotting. In vivo antitumor efficacy was evaluated, and immune microenvironment dynamics were characterized via transcriptomic sequencing, immunohistochemistry, and flow cytometry, with all animal experiments randomized and blinded. RRx-001 markedly reduced NADPH levels by downregulating G6PD, leading to redox imbalance (decreased GSH/GSSG ratio, elevated ROS) and F-actin cytoskeletal contraction—hallmarks of disulfidptosis. This process was partially reversed by the disulfide reductant TCEP, confirming disulfidptosis dependency; quantitative F-actin fluorescence intensity showed significant contraction in RRx-001-treated cells that was mitigated by TCEP co-treatment (
p
 < 0.01). Additionally, RRx-001 promoted the release of damage-associated molecular patterns (DAMPs), including CRT, HMGB1, and HSP70/90, activating ICD, as confirmed by ELISA of extracellular HSP70/90. In vivo, RRx-001 significantly suppressed tumor growth (
p
 < 0.001), reduced tumor weight, enhanced infiltration of CD4+ and CD8+T cells, increased M1 macrophage polarization, and downregulated PD-L1 expression. Transcriptomic analysis implicated enhanced antitumor immunity via T-cell receptor signaling and T-helper cell differentiation pathways. These findings demonstrate that RRx-001 triggers disulfidptosis in HCC by targeting the G6PD–NADPH axis while concurrently inducing ICD, achieving dual metabolic and immunomodulatory effects. This mechanistic insight provides a scientific foundation for developing novel disulfidptosis-based HCC therapies with high translational potential and suggests that future studies should explore the synergistic efficacy of RRx-001 with immune checkpoint inhibitors.