TIM-3/Galectin-9 interaction and glutamine metabolism in AML cell lines, HL-60 and THP-1.

BACKGROUND: T cell immunoglobulin and mucin-domain containing-3 (TIM-3) is a cell surface molecule that was first discovered on T cells. However, recent studies revealed that it is also highly expressed in acute myeloid leukemia (AML) cells and it is related to AML progression. As, Glutamine appears to play a prominent role in malignant tumor progression, especially in their myeloid group, therefore, in this study we aimed to evaluate the relation between TIM-3/Galectin-9 axis and glutamine metabolism in two types of AML cell lines, HL-60 and THP-1. METHODS: Cell lines were cultured in RPMI 1640 which supplemented with 10% FBS and 1% antibiotics. 24, 48, and 72 h after addition of recombinant Galectin-9 (Gal-9), RT-qPCR analysis, RP-HPLC and gas chromatography techniques were performed to evaluate the expression of glutaminase (GLS), glutamate dehydrogenase (GDH) enzymes, concentration of metabolites; Glutamate (Glu) and alpha-ketoglutarate (α-KG) in glutaminolysis pathway, respectively. Western blotting and MTT assay were used to detect expression of mammalian target of rapamycin complex (mTORC) as signaling factor, GLS protein and cell proliferation rate, respectively. RESULTS: The most mRNA expression of GLS and GDH in HL-60 cells was seen at 72 h after Gal-9 treatment (p = 0.001, p = 0.0001) and in THP-1 cell line was observed at 24 h after Gal-9 addition (p = 0.001, p = 0.0001). The most mTORC and GLS protein expression in HL-60 and THP-1 cells was observed at 72 and 24 h after Gal-9 treatment (p = 0.0001), respectively. MTT assay revealed that Gal-9 could promote cell proliferation rate in both cell lines (p = 0.001). Glu concentration in HL-60 and α-KG concentration in both HL-60 (p = 0.03) and THP-1 (p = 0.0001) cell lines had a decreasing trend. But, Glu concentration had an increasing trend in THP-1 cell line (p = 0.0001). CONCLUSION: Taken together, this study suggests TIM-3/Gal-9 interaction could promote glutamine metabolism in HL-60 and THP-1 cells and resulting in AML development.

PD-L1 stimulation can promote proliferation and survival of leukemic cells by influencing glucose and fatty acid metabolism in acute myeloid leukemia.

BACKGROUND: Leukemic cell metabolism plays significant roles in their proliferation and survival. These metabolic adaptations are under regulation by different factors. Programmed Death Ligand -1 (CD-274) is one of the immune checkpoint ligands that do not only cause the immune escape of cancer cells, but also have some intracellular effects in these cells. PD-L1 is overexpressed on leukemic stem cells and relates with poor prognosis of AML. In this study, we investigated effects of PD-L1 stimulation on critical metabolic pathways of glucose and fatty acid metabolisms that have important roles in proliferation and survival of leukemic cells. METHODS: After confirmation of PD-L1 expression by flow cytometry assay, we used recombinant protein PD-1 for stimulation of the PD-L1 on two AML cell lines, HL-60 and THP-1. Then we examined the effect of PD-L1 stimulation on glucose and fatty acid metabolism in cells at the genomic and metabolomic levels in a time dependent manner. We investigated expression changes of rate limiting enzymes of theses metabolic pathways (G6PD, HK-2, CPT1A, ATGL1 and ACC1) by qRT-PCR and also the relative abundance changes of free fatty acids of medium by GC. RESULTS: We identified a correlation between PD-L1 stimulation and both fatty acid and glucose metabolism. The PD-L1 stimulated cells showed an influence in the pentose phosphate pathway and glycolysis by increasing expression of G6PD and HK-2 (P value = 0.0001). Furthermore, PD-L1 promoted fatty acid ß-oxidation by increasing expression of CPT1A (P value = 0.0001), however, their fatty acid synthesis was decreased by reduction of ACC1 expression (P value = 0.0001). CONCLUSION: We found that PD-L1 can promote proliferation and survival of AML stem cells probably through some metabolic changes in leukemic cells. Pentose phosphate pathway that has a critical role in cell proliferation and fatty acids ß-oxidation that promote cell survival, both are increased by PD-L1 stimulation on AML cells.

TIM-3/Gal-9 interaction affects glucose and lipid metabolism in acute myeloid leukemia cell lines.

Introduction: T-cell immunoglobulin and mucin domain-3 (TIM-3) is a transmembrane molecule first identified as an immunoregulator. This molecule is also expressed on leukemic cells in acute myeloid leukemia and master cell survival and proliferation. In this study, we aimed to explore the effect of TIM-3 interaction with its ligand galectin-9 (Gal-9) on glucose and lipid metabolism in AML cell lines. Methods: HL-60 and THP-1 cell lines, representing M3 and M5 AML subtypes, respectively, were cultured under appropriate conditions. The expression of TIM-3 on the cell surface was ascertained by flow cytometric assay. We used real-time PCR to examine the mRNA expression of GLUT-1, HK-2, PFKFB-3, G6PD, ACC-1, ATGL, and CPT-1A; colorimetric assays to measure the concentration of glucose, lactate, GSH, and the enzymatic activity of G6PD; MTT assay to determine cellular proliferation; and gas chromatography-mass spectrometry (GC-MS) to designate FFAs. Results: We observed the significant upregulated expression of GLUT-1, HK-2, PFKFB-3, ACC-1, CPT-1A, and G6PD and the enzymatic activity of G6PD in a time-dependent manner in the presence of Gal-9 compared to the PMA and control groups in both HL-60 and THP-1 cell lines (p > 0.05). Moreover, the elevation of extracellular free fatty acids, glucose consumption, lactate release, the concentration of cellular glutathione (GSH) and cell proliferation were significantly higher in the presence of Gal-9 compared to the PMA and control groups in both cell lines (p < 0.05). Conclusion: TIM-3/Gal-9 ligation on AML cell lines results in aerobic glycolysis and altered lipid metabolism and also protects cells from oxidative stress, all in favor of leukemic cell survival and proliferation.