Reactive oxygen species (ROS) act as double-edged swords in cancer biology—facilitating tumor growth, survival, and metastasis at moderate levels while inducing oxidative damage and cell death when exceeding cellular buffering capacity. To survive under chronic oxidative stress, cancer cells rely on robust antioxidant systems such as the glutathione (GSH) and thioredoxin (Trx), and superoxide dismutases (SODs). These systems maintain redox homeostasis and sustain ROS-sensitive signaling pathways including MAPK/ERK, PI3K/Akt/mTOR, NF-κB, STAT3, and HIF-1α. Targeting the antioxidant defense mechanisms of cancer cells has emerged as a promising therapeutic strategy. Inhibiting the glutathione system induces ferroptosis, a non-apoptotic form of cell death driven by lipid peroxidation, with compounds like withaferin A and altretamine showing strong preclinical activity. Disruption of the Trx system by agents such as PX-12 and dimethyl fumarate (DMF) impairs redox-sensitive survival signaling. Trx reductase inhibition by auranofin or mitomycin C further destabilizes redox balance, promoting mitochondrial dysfunction and apoptosis. SOD1 inhibitors, including ATN-224 and disulfiram, selectively enhance oxidative stress in tumor cells and are currently being tested in clinical trials. Mounting preclinical and clinical evidence supports redox modulation as a cancer-selective vulnerability. Pharmacologically tipping the redox balance beyond the threshold of cellular tolerance offers a rational and potentially powerful approach to eliminate malignant cells while sparing healthy tissue, highlighting novel strategies for targeted cancer therapy at the interface of redox biology and oncology.

Cells constantly face the challenge of managing oxidants. In aerobic organisms, oxygen (O₂) is used for energy production, generating reactive oxygen species (ROS) as byproducts of enzymatic reactions. To protect against oxidative damage, cells possess an intricate system of redox scavengers and antioxidant enzymes, collectively forming the antioxidant defense system. This system maintains the redox equilibrium and enables the generation of localized oxidative signals that regulate essential cellular functions. One key component of this defense is the thioredoxin (Trx) system, which includes Trx, thioredoxin reductase (TrxR), and NADPH. The Trx system reverses oxidation of macromolecules and indirectly neutralizes ROS via peroxiredoxin (Prx). This dual function protects cells from damage accumulation and supports physiological cell signaling. However, the Trx system also shields tumors from oxidative damage, aiding their survival. Due to elevated ROS levels from their metabolism, tumors often rely on the Trx system. In addition, the Trx system regulates critical pathways such as proliferation and neoangiogenesis, which tumors exploit to enhance growth and optimize nutrient and oxygen supply. Consequently, the Trx system is a potential target for cancer therapy. The challenge lies in selectively targeting malignant cells without disrupting the redox equilibrium in healthy cells. The aim of this review article is threefold: first, to elucidate the function of the Trx system; second, to discuss the Trx system as a potential target for cancer therapies; and third, to present the possibilities for inhibiting key components of the Trx system, along with an overview of the latest clinical studies on these inhibitors.

Reactive oxygen species (ROS) are versatile determinants of cell fate, tipping the balance between survival and death. By exceeding critical thresholds or perturbing compartment-specific signaling, ROS can initiate, modulate, or suppress regulated cell death (RCD). Importantly, their influence extends across the full spectrum of currently characterized RCD modalities. 19 distinct forms of cell death—including both long-established and recently described entities—are shaped by ROS, either as triggers, modulators, or inhibitors. Beyond pathway-specific effects, ROS promote crosstalk between death programs, enabling switches from one mode to another and determining whether outcomes are inflammatory or non-inflammatory. By systematically integrating 19 RCD types, the unifying role of ROS emerges as both gatekeeper and connector of diverse death pathways. Such a comprehensive perspective underscores the centrality of redox imbalance in cell fate control and highlights its broader implications for inflammation and disease.

Reactive oxygen species (ROS) are widely recognized as intracellular signaling mediators and contributors to oxidative damage. Increasing evidence indicates that redox processes in the extracellular space constitute a distinct and functionally relevant layer of immune regulation. Extracellular ROS are generated in a spatially and temporally controlled manner by immune and non-immune cells and are shaped by local antioxidant buffering, redox-active metabolites, and tissue architecture. Rather than acting as diffuse by-products of inflammation, extracellular redox conditions modulate immune cell activation, migration, and intercellular communication by influencing surface-associated signaling events and receptor responsiveness. Physiological redox control in the extracellular compartment supports host defense, tissue repair, and coordinated immune responses. In contrast, disruption of spatial redox regulation promotes chronic inflammation, immune dysfunction, cancer-associated immune suppression, and systemic inflammatory states such as sepsis. Loss of redox confinement and insufficient extracellular buffering uncouple redox signaling from its regulatory function and contribute to endothelial dysfunction, immune dysregulation, and tissue injury. Together, these observations identify the extracellular redox balance as an integral component of immune regulation with important implications for understanding inflammatory pathology and for the development of strategies that preserve localized redox control rather than globally suppressing ROS.