Abstract
Esophageal squamous cell carcinoma (ESCC) is a highly aggressive malignancy with limited therapeutic options and a high incidence in East Asia. Gain-of-function mutations in nuclear factor erythroid 2-related factor 2 (Nrf2) are a major driver of ESCC progression, however, pharmacological interventions capable of effectively suppressing mutant Nrf2 signaling are currently lacking. Here, we conducted a high-throughput screen of 2141 natural products using Nrf2 reporter assays, fluorescence polarization, and Nrf2-dependent assays, and identified gambogenic acid (GNA) as a Nrf2-targeted inhibitor that preferentially attenuates oncogenic signaling driven by Nrf2 gain-of-function mutations in ESCC. GNA exhibited preferential anti-tumor activity in Nrf2-mutant ESCC cells compared with wild-type controls, both in vitro and in vivo. GNA also enhanced the chemosensitivity of Nrf2-mutant ESCC to cisplatin. Mechanistically, GNA suppressed the expression of Nrf2-driven ARE genes and modulated amino acid metabolism and mRNA translation by promoting cysteine oxidation in translational regulatory proteins within Nrf2-mutant cells. Importantly, GNA induced polymerization of the Nrf2/MafG protein complex and promoted its ubiquitin-mediated proteasomal degradation, thereby uncovering a previously uncharacterized mechanism of inhibition targeting the Nrf2/MafG axis. Collectively, our study identifies GNA as a promising therapeutic candidate that preferentially suppresses mutant Nrf2 signaling and shows therapeutic potential in Nrf2-driven ESCC.