GPX4-AUTAC induces ferroptosis in breast cancer by promoting the selective autophagic degradation of GPX4 mediated by TRAF6-p62

Abstract

Emerging evidence indicates that activation of ferroptosis by inhibition of glutathione peroxidase 4 (GPX4) may be exploited as a therapeutic strategy to suppress tumor growth and progression. However, application of GPX4 inhibitors in cancer treatment is hampered by their poor selectivity, which results in unfavorable toxicity. Herein, we identified GPX4 as a candidate for the autophagy pathway. We showed that GPX4 is ubiquitinated by TNF receptor-associated factor 6 (TRAF6), which promotes its recognition by p62 and leads to its selective autophagic degradation. Utilizing targeted protein degradation (TPD) approach, we developed a GPX4-targeted AUTAC and demonstrated that GPX4-AUTAC promoted the ubiquitination of GPX4, and enhanced the binding with GPX4 and p62, leading to the selective autophagy-dependent degradation of GPX4. Furthermore, GPX4-AUTAC treatment strongly induced ferroptosis and exhibited potent anti-cancer activity against breast cancer in vitro, in vivo, and patient-derived organoids (PDOs). Combination treatment of GPX4-AUTAC with sulfasalazine, a ferroptotic inducer, or chemotherapy drugs showed a synergistic anti-cancer effect against breast cancer. These results uncover a new targeted degradation strategy for GPX4 by inducing selective autophagy and provide a rationale for the use of GPX4-AUTAC as a novel therapeutic approach to treatment of breast cancer.