GPX4 inhibitors (Hainan University)

Ferroptosis is an iron-dependent mode of cell death that is driven by phospholipid peroxides. Ferroptosis inducers (FINs) are a new paradigm in cancer treatment as several therapy-resistant cancer cells are sensitive to ferroptosis. System x_c^- and glutathione peroxidase 4 (GPX4) are two predominant targets of FINs. Although GPX4 inhibitors prevent the reduction of lipid peroxides, system x_c^- inhibitors block glutathione biosynthesis and indirectly inhibit GPX4. In this review, we provide an updated summary of GPX4 and system x_c^- inhibitors, as well as GPX4 degraders. We also discuss the shortcomings that impede the clinical success of these FINs for cancer treatment.

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.