Modulation of NRF2: Biological Dualism in Cancer, Targets and Possible Therapeutic Applications

The nuclear factor erythroid 2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) system is a master regulator of redox homeostasis and cell adaptation to a variety of exogenous and endogenous stressors. Accumulating evidence from the last decade indicates that the impairment of the redox balance leads to oxidative stress (OS), a common alteration occurring in many human acute and chronic inflammatory diseases, such as cancer, diabetes, neurodegeneration, and metabolic disorders, and aging. Being located at the intersection of crucial signaling pathways, NRF2 can influence several cellular functions, which extend beyond the maintenance of the redox balance and include cellular metabolism, proteostasis, mitochondrial function and inflammation. For this reason, there is a growing interest in the pharmacologic manipulation of NRF2 for therapeutic purposes, which requires the accurate knowledge of the cell context and the specific time frame both of NRF2 activation and inhibition. This appears to be an important prerequisite and reflects the extreme complexity of the NRF2 signaling, characterized by an intrinsic dualism that mediates beneficial or detrimental effects even in the same biological process. Of crucial importance will be to understand whether the NRF2 activity modulation might be exploited to exert beneficial outcomes in patients suffering from pathological conditions, in which the OS and the deregulation of inflammatory processes play a crucial role. In this review, we discuss the dual involvement of NRF2 in aging, neurodegeneration, metabolic diseases, long-COVID-19, and carcinogenesis and we present an overview of the most recent therapeutic modulators of NRF2, particularly emphasizing on those selected for clinical trials. Antioxid. Redox Signal. 40, 636-662.