Targeting Glutathione Metabolism Enhances Tumor Radiosensitization by Intensifying Oxidative Stress

Radiotherapy is a foundational treatment for cancer, primarily inducing tumor cell death via reactive oxygen species (ROS) generation. However, high levels of glutathione (GSH) within tumor cells act as potent ROS scavengers, significantly compromising radiotherapy efficacy and fostering radioresistance. This metabolic adaptation represents a critical therapeutic gap, as current standard-of-care often struggles against tumors with robust antioxidant defenses. Understanding and modulating redox regulation in cancer, specifically targeting GSH metabolism, is therefore paramount for improving clinical outcomes.

This comprehensive review systematically described the mechanisms through which glutathione (GSH) metabolism contributes to tumor radioresistance. It surveyed a broad range of novel therapeutic approaches aimed at inhibiting GSH synthesis or promoting its depletion. The review encompassed both pharmacological compounds and advanced nanotechnology-enabled delivery systems. The primary focus was on strategies demonstrating the ability to intensify oxidative stress specifically in tumors characterized by high GSH content, thereby enhancing their susceptibility to radiation.

The review elucidated that elevated intracellular glutathione (GSH) levels are a primary driver of tumor radioresistance, acting by efficiently scavenging radiation-induced ROS. This protective mechanism allows cancer cells to evade oxidative damage and survive therapeutic doses. Several strategies to overcome this were identified: inhibition of GSH synthesis, often by targeting enzymes like γ-glutamylcysteine ligase (GCL), and direct GSH depletion through agents that oxidize or conjugate GSH. Pharmacological compounds, such as buthionine sulfoximine (BSO), were highlighted for their ability to sensitize tumors by reducing GSH. Furthermore, advanced nanotechnology platforms, including nanoparticles loaded with GSH inhibitors or ROS generators, demonstrated enhanced tumor specificity and reduced systemic toxicity. > The most impactful finding is that by strategically reducing tumor GSH, either through synthesis inhibition or direct depletion, the oxidative stress induced by radiotherapy is significantly amplified, leading to enhanced tumor cell death.