Arginine Deprivation induces ROS Dependent Autophagic Cell Death in Human Acute Myeloid Leukemia Cells

In this study, we assess the activation of autophagy and its impact on cytotoxicity following [HuArgI (Co)-PEG5000]-induced arginine deprivation in AML cells. We have previously shown that arginine deprivation is selectively cytotoxic to AML cells and that cell death is caspase independent and non-apoptotic, hence the mechanism of cell death remained elusive. We tested a panel of 6 AML cell lines, and we first demonstrated that the cytotoxicity of [HuArgI (Co)-PEG5000] to AML cells is long-term and sustained despite re-expression of overexpression of ASS1 in all cell lines. We also demonstrated that arginine deprivation leads to a prolonged and extensive activation of autophagy starting at 24 and lasting up to 120 hours in all cells. Autophagy was shown to induce cell death since its inhibition using chloroquine (CQ) significantly decreased [HuArgI (Co)-PEG5000]-induced cytotoxicity, indicating autophagic cell death in AML cells following arginine deprivation. Moreover, we showed that arginine deprivation leads to ROS accumulation and that neutralizing ROS using N-acetylcysteine (NAC) does not affect the autophagic response but completely reverses the cytotoxicity of arginine deprivation, demonstrating that death by autophagy is dependent on ROS generation in AML cells.