Abstract 7201: Targeting SLC38A1 non-conventional glutamine transporter in high risk MDS/AML

Abstract Introduction: Myelodysplastic syndrome (MDS) is a malignant clonal hematopoietic disorder characterized by ineffective hematopoiesis, bone marrow dysplasia, and a tendency to transform into acute myeloid leukemia (AML) in about 30% of cases. Cancer cells are known to rely on glutamine as a source of energy. We have reported that inhibition of glutaminase (GLS), a key enzyme in glutaminolysis, with CB-839 combined with 5-azacytidine has synergistic activity in AML/MDS in vitro and in vivo models and is associated with durable responses in patients with advanced MDS (DiNardo et al., Nat Cancer 2024). Glutamine uptake is tightly regulated by members of the large solute carrier (SLC) superfamily. We found that SLC38A1, a non-canonical glutamine transporter, is significantly and selectively overexpressed in long-term hematopoietic stem cells (LT-HSCs) in patients with MDS and AML and associated with reduced overall survival. Based on these findings, we hypothesize that SLC38A1 represents a promising therapeutic target and that inhibiting critical tumor-specific metabolic pathways will selectively target MDS stem cells responsible for AML transformation. Methods: Intracellular metabolites were extracted using a modified Bligh-Dyer procedure and analyzed by ultra-high-performance liquid chromatography tandem ultra high-resolution mass spectrometry (UHPLC-HRMS) technology. SiRNA and CRISPR mediated knockdown of SLC38A1 were done in cell lines and patient samples using Amaxa nucleofection. Colony forming assay was done using human methylcellulose enriched media. Results: Functional relevance of SLC38A1 was shown by metabolic flux analysis of siRNA-mediated SLC38A1 depletion in HEL cells and knockdown of OCI-AML-3 with CRISPR guide RNAs which demonstrated reduced glutamine transport with corresponding reduction of glutamate and aspartate levels. MeAiB (α-(methylamino)-isobutyric acid), a non-metabolized amino acid analogue and competitive inhibitor of system “A” SNAT family transporters including SLC38A1, reduced AML cell viability in MOLM14 and MV4-11 cell lines. Knock-down of SLC38A1 reduced the number of surviving colonies by 37%, 42% and 43% in MOLM13, THP-1 and MDS-L cells, respectively. SLC38A1 KO in MOLM13 and THP-1 cells attenuated cell proliferation and reduced cell viability compared to control cells. SLC38A1 KO in primary AML and high risk MDS patient samples (n=4) reduced cell viability and colony formation. Additional primary samples are being tested and will be reported. Conclusion: These findings suggest that inhibition of the import function of glutamine transporter SLC38A1 may be therapeutically beneficial to target the metabolic reprogramming in high risk MDS/AML. Chemical library screening is ongoing and has identified initial tool SLC38A1 inhibitors. Citation Format: Akansha Jalota, Anna Skwarska, Divij Verma, Kith Pradhan, Sovira Chaudhry, Gowri Poigaialwar, Vijaya Shukla, Yaxia Yuan, Elvin Wagenblast, Daohong Zhou, Stefano Tiziani, Amit Verma, Marina Konopleva. Targeting SLC38A1 non-conventional glutamine transporter in high risk MDS/AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7201.