GSH-Related Enzymes GPx4, Chac1, and GSTs and Redox Regulation of Ferroptosis in Cancer

The tripeptide glutathione (GSH) is the most abundant cellular non-enzymatic antioxidant. The GSH system plays a crucial role in antioxidant defense against oxidative stress and in supporting cellular redox homeostasis, regulating the reduction of lipid peroxides, and protecting cells from ferroptosis depending on the GSH level, which is maintained in a state of dynamic equilibrium not only by the activities of GSH synthesis enzymes, transporters of GSH precursor amino acids, and GSH transporters, but also by the actions of GSH-related enzymes. Some GSH-related enzymes are key enzymes with antioxidant functions such as glutathione peroxidases (GPxs), especially GPx4, and glutathione S-transferases (GSTs), which use GSH as a co-substrate for the reduction of hydroperoxides to alcohols, whereas glutathione-specific gamma-glutamyl cyclotransferase 1 (ChaC1) degrades intracellular GSH, so they can correspondingly lead to suppression or induction of ferroptosis. Ferroptosis is characterized by a buildup of lipid peroxides due to excessive lipid peroxidation and iron accumulation, which results from redox imbalance between ferroptosis's drivers and defense systems, including impaired cellular antioxidant systems, particularly disruptions of GSH metabolism. It appears pertinent to assess the influence on ferroptosis regulation by GSH-dependent enzymes that utilize the GSH pool in diverse ways. This review offers an updated exploration of the roles of GPx4, ChaC1, and GSTs in redox regulation of ferroptosis in cancer cells, with a focus on both the regulation of each enzyme's activity and their possible interactions, considering the impact on the risk of ferroptosis induction.