Abstract 2991: Targeting glutamine metabolism leads to terminal differentiation in acute myeloid leukemia (AML)
Authors: Leone Robert , Sun Im-Meng , Chikarmane Roshan , Viswanathan Radhika , Patwari Sanjeda , Arwood Matthew , Ghiaur Gabriel , Powell Jonathan 
Published: August 2019

Abstract
The ability of All Trans Retinoic Acid (ATRA) to induce terminal differentiation in Acute Promyelocytic Leukemia (APL) has revolutionized treatment for this deadly subset of AML. Unfortunately, identifying targets that induce differentiation in non-APL cases of AML has met with limited success. Our lab has been interested in the role of glutamine metabolism in cellular differentiation programs. As such, we have investigated the degree to which glutamine contributes to the maintenance of an undifferentiated state in AML. Herein, we report that in vitro incubation with the glutamine blocking agent, 6-diazo-5-oxo-L-norleucine (DON) robustly induces differentiation in the human AML cell line, U937. DON treatment induces phenotypic and molecular changes indicative of differentiation, including increased granularity and vacuolization, and upregulation of differentiation markers CD11b and CD14. The differentiation of these cells was confirmed by their highly abrogated growth in methylcellulose-based colony-forming assays. Differentiated AML cells were not exposed to DON during colony-forming assays, suggesting an irreversible change in cellular differentiation triggered by short-term pretreatment. We have demonstrated that DON-induced cellular differentiation is active in other AML cell lines as well. Importantly, the differentiating effect of DON can be abrogated by the addition of a cell permeable form of α-ketoglutarate (αKG), dimethyl-2-ketoglutarate (DMK). αKG is a key metabolite in glutamine metabolism and is also a critical cofactor for a range of demethylase enzymes involved in epigenetic remodeling. Indeed, we have noted a robust increase in histone methylation marks, such as H3K27Me3, during DON-induced differentiation. Further, we have observed a dramatic increase in the transcription of critical transcription factors (CEBPA, FLT3, MYB, SOX4) twenty-four hours after DON treatment, a time point immediately preceding observed phenotypic differentiation changes. In light of these findings, experiments are currently underway to use DON differentiation therapy as a means of treating mouse models of AML. Taken as a whole, these data support the use of glutamine blockade as a novel differentiating therapy in AML. Given the remarkable curative potential of differentiation therapy and the poor survival rates of adults with AML (particularly older patients), our findings represent a particularly novel approach to treating this deadly disease.
Citation Format: Robert Leone, Im-Meng Sun, Roshan Chikarmane, Radhika Viswanathan, Sanjeda Patwari, Matthew Arwood, Gabriel Ghiaur, Jonathan Powell. Targeting glutamine metabolism leads to terminal differentiation in acute myeloid leukemia (AML) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2991.