glutaminase and Multiple-Myeloma

Cancer is associated with metabolic changes from increased cell proliferation and growth. Compared to normal differentiated cells, MM cells use the glycolytic pathway even when adequate oxygen is present triggering "Glutamine addiction".. To investigate the single and combined effects of epigallocatechin-3-gallate (EGCG) and telaglenastat, a glutaminase inhibitor, on the proliferation and apoptosis of the multiple myeloma cell line KM3/BTZ.. KM3/BTZ cells were treated with different concentrations of telaglenastat and EGCG alone or in combination to investigate their effect on proliferation and apoptosis using the CCK8 assay, flow cytometry, and western blotting. The Chou-Talalay combination index analysis was used to explore the effect of telaglenastat combined with EGCG, while the Combination Index (CI) was calculated to analyze whether the combination of the two drugs had a synergistic effect.. Telaglenastat and EGCG alone as well as in combination (5 μmol/L telaglenastat + 120 μmol/L EGCG) significantly inhibited the proliferation of KM3/BTZ cells compared to the inhibition effect of the control. Additionally, the combined treatment increased the proportion of KM3/BTZ cells in the G2 phase and decreased the proportion of cells in the G1 phase. The apoptosis rate of EGCG alone and the combined treatment was significantly higher than that of the control group. Bax protein expression was highest in the combined treatment group, whereas Bcl-2 expression was lowest, with the combined treatment group having the highest ratio of Bax/Bcl-2.. Telaglenastat and EGCG act synergistically to inhibit cell proliferation and promote apoptosis in KM3/BTZ cells, possibly by targeting glutamine metabolism and glycolysis.

Topics: Apoptosis; Catechin; Cell Line, Tumor; Cell Proliferation; Glutaminase; Glutamine; Humans; Multiple Myeloma; Proto-Oncogene Proteins c-bcl-2

Curative responses in the treatment of multiple myeloma (MM) are limited by the emergence of therapeutic resistance. To address this problem, we set out to identify druggable mechanisms that convey resistance to proteasome inhibitors (PIs; e.g., bortezomib), which are cornerstone agents in the treatment of MM. In isogenic pairs of PI sensitive and resistant cells, we observed stark differences in cellular bioenergetics between the divergent phenotypes. PI resistant cells exhibited increased mitochondrial respiration driven by glutamine as the principle fuel source. To target glutamine-induced respiration in PI resistant cells, we utilized the glutaminase-1 inhibitor, CB-839. CB-839 inhibited mitochondrial respiration and was more cytotoxic in PI resistant cells as a single agent. Furthermore, we found that CB-839 synergistically enhanced the activity of multiple PIs with the most dramatic synergy being observed with carfilzomib (Crflz), which was confirmed in a panel of genetically diverse PI sensitive and resistant MM cells. Mechanistically, CB-839 enhanced Crflz-induced ER stress and apoptosis, characterized by a robust induction of ATF4 and CHOP and the activation of caspases. Our findings suggest that the acquisition of PI resistance involves adaptations in cellular bioenergetics, supporting the combination of CB-839 with Crflz for the treatment of refractory MM.

Topics: Aged; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzeneacetamides; Biomarkers; Cell Line, Tumor; Cell Respiration; Cell Survival; Drug Resistance, Neoplasm; Drug Synergism; Endoplasmic Reticulum Stress; Energy Metabolism; Glutaminase; Humans; Mitochondria; Multiple Myeloma; Oligopeptides; Proteasome Inhibitors; Thiadiazoles

The importance of glutamine (Gln) metabolism in multiple myeloma (MM) cells and its potential role as a therapeutic target are still unknown, although it has been reported that human myeloma cell lines (HMCLs) are highly sensitive to Gln depletion. In this study, we found that both HMCLs and primary bone marrow (BM) CD138(+) cells produced large amounts of ammonium in the presence of Gln. MM patients have lower BM plasma Gln with higher ammonium and glutamate than patients with indolent monoclonal gammopathies. Interestingly, HMCLs expressed glutaminase (GLS1) and were sensitive to its inhibition, whereas they exhibited negligible expression of glutamine synthetase (GS). High GLS1 and low GS expression were also observed in primary CD138(+) cells. Gln-free incubation or treatment with the glutaminolytic enzyme l-asparaginase depleted the cell contents of Gln, glutamate, and the anaplerotic substrate 2-oxoglutarate, inhibiting MM cell growth. Consistent with the dependence of MM cells on extracellular Gln, a gene expression profile analysis, on both proprietary and published datasets, showed an increased expression of the Gln transporters SNAT1, ASCT2, and LAT1 by CD138(+) cells across the progression of monoclonal gammopathies. Among these transporters, only ASCT2 inhibition in HMCLs caused a marked decrease in Gln uptake and a significant fall in cell growth. Consistently, stable ASCT2 downregulation by a lentiviral approach inhibited HMCL growth in vitro and in a murine model. In conclusion, MM cells strictly depend on extracellular Gln and show features of Gln addiction. Therefore, the inhibition of Gln uptake is a new attractive therapeutic strategy for MM.

Topics: Adult; Aged; Aged, 80 and over; Amino Acid Transport System ASC; Ammonium Compounds; Animals; Asparaginase; Biological Transport; Cell Line, Tumor; Cell Proliferation; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gene Silencing; Glutamate-Ammonia Ligase; Glutaminase; Glutamine; Humans; Male; Membrane Transport Proteins; Mice, Inbred NOD; Mice, SCID; Middle Aged; Minor Histocompatibility Antigens; Molecular Targeted Therapy; Monoclonal Gammopathy of Undetermined Significance; Multiple Myeloma; Syndecan-1