Arginine Deprivation in AML Cells Induces Ferroptosis, a Type of Autophagy-Mediated Cell Death

Abstract

In this study, we showed for the first time that arginine deprivation using a recombinant human arginase induces ferroptosis, an autophagy-mediated type of cell death in AML cells. Acute Myeloid Leukemia (AML) poses significant challenges due to its unfavorable prognosis and limited treatment options, particularly in elderly patients. The investigation of arginine depleting enzymes, such as [HuArgI(Co)-PEG5000], has shown promise in selectively inducing cytotoxicity in various cancer cells, including AML. This study aims to explore the cell death mechanism induced by [HuArgI(Co)-PEG5000] and its potential association with ferroptosis, a newly identified iron-dependent form of regulated cell death characterized by ROS accumulation and lipid peroxidation. Our results demonstrate that the cytotoxicity of [HuArgI(Co)-PEG5000] in AML cells leads to the generation of reactive oxygen species (ROS). Scavenging ROS using NAC significantly decreases cell death but has minimal effect on autophagy activation, suggesting that the accumulation of ROS is downstream of autophagy activation but upstream of cell death. This involvement of ROS is confirmed with the gradual increase in intracellular ROS levels, reaching a peak at 48 hours after treatment. This is followed by an increase in lipid peroxidation which peaks at later timepoints and varies between different cell lines. Studying expression levels of regulatory proteins involved in iron homeostasis (FTH1, NCOA4 and DMT1/SLC11A2) and oxidative stress defense (NRF2, KEAP1, AIFM2/FSP1, 4f2hc/CD98, xCT/SLC7A11, and GPX4) suggests altered iron distribution and impaired antioxidant system in treated cells. Overall, these findings provide evidence that arginine deprivation induced by [HuArgI(Co)-PEG5000] leads to increased ROS production, lipid peroxidation, and dysregulation of iron metabolism and antioxidant pathways, all of which are hallmarks for the occurrence of ferroptosis in AML cells following arginine deprivation. Understanding the mechanisms underlying this ferroptotic cell death induced by arginine deprivation may have implications for the development of targeted therapies for AML and other cancer types.