Compelling evidence supports a tight link between oxidative stress and protein aggregation processes, which are noticeably involved in the development of proteinopathies, such as Alzheimer’s disease, Parkinson’s disease, and prion disease. The literature is tremendously rich in studies that establish a functional link between both processes, revealing that oxidative stress can be either causative, or consecutive, to protein aggregation. Because oxidative stress monitoring is highly challenging and may often lead to artefactual results, cutting-edge technical tools have been developed recently in the redox field, improving the ability to measure oxidative perturbations in biological systems. This review aims at providing an update of the previously known functional links between oxidative stress and protein aggregation, thereby revisiting the long-established relationship between both processes.

Fe‐S centers exhibit strong electronic plasticity, which is of importance for insuring fine redox tuning of protein biological properties. In accordance, Fe‐S clusters are also highly sensitive to oxidation and can be very easily altered in vivo by different drugs, either directly or indirectly due to catabolic by‐products, such as nitric oxide species (NOS) or reactive oxygen species (ROS). In case of metal ions, Fe‐S cluster alteration might be the result of metal liganding to the coordinating sulfur atoms, as suggested for copper. Several drugs presented through this review are either capable of direct interaction with Fe‐S clusters or of secondary Fe‐S clusters alteration following ROS or NOS production. Reactions leading to Fe‐S cluster disruption are also reported. Due to the recent interest and progress in Fe‐S biology, it is very likely that an increasing number of drugs already used in clinics will emerge as molecules interfering with Fe‐S centers in the near future. Targeting Fe‐S centers could also become a promising strategy for drug development.

Auranofin (Ridaura^®, AUF) is a gold complex originally approved as an antirheumatic agent that has emerged as a potential candidate for multiple repurposed therapies. The best-studied anticancer mechanism of AUF is the inhibition of thioredoxin reductase (TrxR). However, a number of reports indicate a more complex and multifaceted mode of action for AUF that could be cancer cell type- and dose-dependent. In this study, we observed that AUF displayed variable cytotoxicity in five triple-negative breast cancer cell lines. Using representative MDA-MB-231 cells treated with moderate and cytotoxic doses of AUF, we evidenced that an AUF-mediated TrxR inhibition alone may not be sufficient to induce cell death. Cytotoxic doses of AUF elicited rapid and drastic intracellular oxidative stress affecting the mitochondria, cytoplasm and nucleus. A “redoxome” proteomics investigation revealed that a short treatment with a cytotoxic dose AUF altered the redox state of a number of cysteines-containing proteins, pointing out that the cell proliferation/cell division/cell cycle and cell–cell adhesion/cytoskeleton structure were the mostly affected pathways. Experimentally, AUF treatment triggered a dose-dependent S-phase arrest and a rapid disintegration of the actin cytoskeleton structure. Our study shows a new spectrum of AUF-induced early effects and should provide novel insights into the complex redox-based mechanisms of this promising anticancer molecule.

B-type eukaryotic polymerases contain a [4Fe-4S] cluster in their C-terminus domain, whose role is not fully understood yet. Among them, DNA polymerase delta (Polδ) plays an essential role in chromosomal DNA replication, mostly during lagging strand synthesis. Previous in vitro work suggested that the Fe-S cluster in Polδ is required for efficient binding of the Pol31 subunit, ensuring stability of the Polδ complex. Here, we analyzed the in vivo consequences resulting from an impaired coordination of the Fe-S cluster in Polδ. We show that a single substitution of the very last cysteine coordinating the cluster by a serine is responsible for the generation of massive DNA damage during S phase, leading to checkpoint activation, requirement of homologous recombination for repair, and ultimately to cell death when the repair capacities of the cells are overwhelmed. These data indicate that impaired Fe-S cluster coordination in Polδ is responsible for aberrant replication. More generally, Fe-S in Polδ may be compromised by various stress including anti-cancer drugs. Possible in vivo Polδ Fe-S cluster oxidation and collapse may thus occur, and we speculate this could contribute to induced genomic instability and cell death, comparable to that observed in pol3-13 cells.

During their inevitable evolution towards acquired resistance to anti-cancer targeted therapies, cancer cells adopt distinct gene expression profiles that allow them to transiently adapt to and tolerate the treatment. Cancer cells surviving therapy can increase their mutation rate, enhancing the likelihood of acquiring resistance-conferring mutations and evolving into resistant cells. Here we show that translational control mediates the adaptive mutability of melanoma drug-tolerant cells by regulating the translation of the error-prone non-homologous end joining (NHEJ) component 53BP1 . The specific inhibition of 5’UTR-driven 53BP1 mRNA translation was sufficient to impair NHEJ and mutability. We found that the eIF4A RNA helicase, regulates 53BP1 mRNA translation. Consequently, targeting the eIF4A with two small molecule inhibitors significantly delays the acquisition of resistance to combination of BRAF and MEK inhibitors in BRAF ^V600 -mutant melanoma xenograft models and cell lines by reducing the mutability of drug-tolerant cells. Our results demonstrate that a standard-of-care therapy for melanoma, by engaging non-genetic adaptation driven at the translational level, contributes to the evolution of drug-tolerant melanoma cells toward acquired resistance.