Role of amino acids in regulation of ROS balance in cancer.

Cancer cells display increased oxidative stress from reactive oxygen species (ROS) and constantly have to counteract them below a tolerable threshold to avoid any toxicity due to overload of ROS. The involvement of ROS in cancer progression from precursor lesions to aggressive tumor and metastasis formation is still debated, but it is recognized that cancer cells succeed to use ROS for their own benefit in circumstances that are tumor cell-type specific. In this review, we focus on amino acids' metabolic pathways that tumor cells activate as antioxidants including cysteine, methionine metabolisms and their connection with the folate, transulfuration pathways and ferroptosis. We discuss how the tumor context definitively dictates the impact of ROS on tumor progression towards a metastatic disease as well as the therapeutic approaches that target ROS to abrogate tumors or limit their aggressiveness.