Targeting amino acid transport in acute myeloid leukemia

Details

Supervisors

Van Gastel, Nick ; Morsomme, Pierre

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

Acute myeloid leukemia (AML) is the most common acute leukemia in adults and occurs when malignant hematopoietic stem cells undergo clonal expansion due to the acquisition of genetic abnormalities. Characterized by its aggressive nature, high mortality rate and relapse occurrence, research on AML has been focused on various aspects to further understand the complexity of this heterogenous malignancy. In recent years, one of the promising strategies has been to better understand the unique metabolic dependencies of AML cells in order to identify and target potential metabolic vulnerabilities. Amino acids play an important role in the anabolism of AML and a better characterization of their transport and metabolism could provide opportunities for developing new therapeutic strategies against AML. The aim of this Master thesis is triple: (i) to investigate the impact of different amino acid transporter inhibitors on AML cell metabolism and proliferation, (ii) to develop models to study the roles of key amino acid transporters by knocking them down in AML cell lines, and (iii) to explore single-cell multi-omics analytical tools to investigate the expression levels of amino acid transporters in clonal hematopoiesis, a pre-leukemic state, using data from patients carrying one of the most common mutations found in AML. By measuring metabolic activity and conducting cell proliferation and viability assays, this study suggests that L-glutamic acid gamma-monohydroxamate (GAH), a system N amino acid transporter inhibitor, decreases metabolic activity in human AML cell lines at relatively low concentrations. Both GAH and alpha-(methylamino) isobutyric acid (MeIAB), a system A amino acid transporter inhibitor, reduced cell proliferation of different AML cell lines while 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), a system L amino acid transporter inhibitor, showed a synergizing effect with chemotherapeutic agents on cell number in the U937 AML cell line. Metabolomics analysis showed that MeIAB depletes the intracellular levels of nearly all the amino acids while GAH and BCH were more selective revealing the importance of different amino acid transporter families for AML metabolism. The second aim was to generate SLC38A1 and SLC38A2 knock-down AML cell lines by using target-specific shRNAs. Although several shRNAs allowed for relatively efficient and specific knockdown of their targets at the mRNA levels, this could not be confirmed at the protein level, likely due to the use of non-specific antibodies, which should be further investigated. Finally, a previously published single-cell multi-omics dataset from patients with clonal hematopoiesis was re-analyzed for amino acid transporter expression. Although statistical significance was not reached, several amino acid transporters appear to be expressed more in mutant hematopoietic stem cells, suggesting that the role of these transporters in the clonal outgrowth of mutant stem cells should be further investigated. Globally, this Master thesis highlights the importance of amino acid transporters for several aspects of AML cell biology, but also underscores a potential redundancy between them.