The Role of Iron in DNA and Genomic Instability in Cancer, a Target for Iron Chelators That Can Induce ROS

Iron is a key metal involved in several biological processes such as DNA replication and repair, cellular proliferation and cell cycle regulation. Excess volumes of labile iron are toxic and can lead to the production of ROS (reactive oxygen species) via Fenton chemistry. Due to this reactive nature, it can contribute to DNA damage and genomic instability. Therefore, excess iron in the labile iron pool is associated with cancer, which has made the labile iron pool a crucial target for anticancer therapy by targeting iron. This iron can be incorporated into essential enzymes such as ribonucleotide reductase (RnR). Over several decades of research, iron chelators function as more than just RnR inhibitors. Indeed, a plethora of iron chelator mechanisms can result in therapeutic properties that can target critical steps of cancer cells’ aberrant biological abilities such as proliferation, migration and metastasis. One such mechanism is the production of redox-active complexes that can produce toxic levels of ROS in cancer cells. Cancer cells are potentially more susceptible to ROS production or modulation of antioxidant levels. Understanding iron metabolism is vital in targeting cancer. For instance, Fe-S clusters have recently been shown to play crucial roles in cell signalling by ROS through their incorporation into essential DNA replication and repair enzymes. ROS can also degrade Fe-S clusters. Iron chelators that produce toxic levels of ROS, therefore, could also target Fe-S centres. Thus, the design of iron chelators is important, as this can determine if it will participate in redox cycling and produce ROS or if it is solely used to remove iron. This review focuses on alterations in cancer iron metabolism, iron’s role in genomic stability and how the design of chelators can use Fenton chemistry to their advantage to cause DNA damage in cancer cells and potentially inhibit Fe-S centres.