glutaminase and Triple-Negative-Breast-Neoplasms

Aggressive cancers such as triple-negative breast cancer (TNBC) avidly metabolize glutamine as a feature of their malignant phenotype. The conversion of glutamine to glutamate by the glutaminase enzyme represents the first and rate-limiting step of this pathway and a target for drug development. Indeed, a novel glutaminase inhibitor (GLSi) has been developed and tested in clinical trials but with limited success, suggesting the potential for a biomarker to select patients who could benefit from this novel therapy. Here, we studied a nonmetabolized amino acid analog,

Topics: Animals; Biomarkers; Carboxylic Acids; Cyclobutanes; Glutaminase; Glutamine; Humans; Kinetics; Mice; Positron-Emission Tomography; Triple Negative Breast Neoplasms

Tumor growth is mediated in part by glutamine, and glutaminase is an enzyme necessary for glutamine catabolism. We studied glutaminase (GLS1) gene expression in primary breast cancer to determine correlations with clinical and tumor characteristics, and gene associations in publicly available databases. A better understanding of glutaminase gene expression may help guide further exploration of glutaminase inhibitors in breast cancer.. GLS1 mRNA levels were evaluated in The Cancer Genome Atlas (n = 817) and METABRIC (n = 1992) datasets. Associations between GLS1 and tumor subtype (ANOVA followed by post-hoc Tukey test for pairwise comparisons) and selected genes involved in the pathogenesis of breast cancer (Pearson's correlations) were determined in both datasets. In METABRIC, associations with overall survival (Cox proportional hazard model) were determined. For all analyses, p < 0.05 was the threshold for statistical significance.. GLS1 expression was significantly higher in triple negative breast cancer (TNBC) than hormone receptor (HR) +/HER2- and HER2+ breast cancer (p < 0.001) and basal versus luminal A, luminal B, and HER2 enriched breast cancer (p < 0.001) in both datasets. In METABRIC, higher GLS1 expression was associated with improved overall survival (HR 0.91, 95% CI: 0.85-0.97, p = 0.005) and this association remained significant in the TNBC subset (HR 0.83, 95% CI: 0.71-0.98, p = 0.032). GLS1 had significant positive gene correlations with immune, proliferative, and basal genes, and inverse correlations with luminal genes and genes involved in metabolism.. GLS1 expression is highest in TNBC and basal breast cancer, supporting ongoing clinical investigation of GLS1 inhibition in TNBC. GLS1 may have prognostic implications but further research is needed to validate this finding. GLS1 had significant positive gene correlations with immune genes, which may have implications for potential combinations of glutaminase inhibition and immunotherapy.

Topics: Breast Neoplasms; Female; Gene Expression; Glutaminase; Glutamine; Humans; Prognosis; Triple Negative Breast Neoplasms

The enzyme glutaminase-1 (GLS-1) has shown a clear and coherent implication in the progression and exacerbation of different aggressive tumors such as glioblastoma, hepatocarcinoma, pancreas, bone, and triple-negative breast cancer. Few chemotypes are currently available as selective GLS-1 inhibitors, and still, fewer of them are at the clinical stage. In the present paper, starting from a naturally-inspired antitumor compound library, metabolomics has been used to putatively identify the molecular mechanism underlying biological activity. GLS-1 was identified as a potential target. Biochemical analysis confirmed the hypothesis leading to the identification of a new hit compound acting as a GLS-1 selective inhibitor (IC

Topics: Cell Line, Tumor; Glutaminase; Humans; Metabolomics; Phenotype; Triple Negative Breast Neoplasms

Glutaminase (GLS) serves a critical bioenergetic role for malignant tumor growth and has become a valuable therapeutic target for cancer treatment. Herein, we performed a structure-based virtual screening to discover novel GLS inhibitors and provide information for developing new GLS inhibitors. We identified critical pharmacological interactions in the GLS1 binding site by analyzing the known GLS1 inhibitors and selected potential inhibitors based on their docking score and pharmacological interactions. The inhibitory effects of compounds were further confirmed by enzymatic and cell viability assays. We treated colorectal cancer and triple-negative breast cancer cells with the selected candidates and measured the inhibitory efficacy of hit compounds on cell viability. In total, we identified three GLS1 inhibitors. The compounds identified from our structure-based virtual screening methodology exhibited great anticancer potential as a lead targeting glutamine metabolism.

Topics: Cell Line, Tumor; Cell Survival; Glutaminase; Glutamine; Humans; Kidney; Triple Negative Breast Neoplasms

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Discovery; Drug Screening Assays, Antitumor; Enzyme Inhibitors; Glutaminase; Humans; Molecular Structure; Pregnenes; Structure-Activity Relationship; Triple Negative Breast Neoplasms

The eukaryotic elongation factor-2 kinase, eEF2K, which restricts protein translation elongation, has been identified as a potential therapeutic target for diverse types of malignancies including triple negative breast cancer (TNBC). However, the contexts in which eEF2K inhibition is essential in TNBC and its consequences on the proteome are largely unknown. Here we show that genetic or pharmacological inhibition of eEF2K cooperated with glutamine (Gln) starvation, and synergized with glutaminase (GLS1) inhibitors to suppress growth of diverse TNBC cell lines. eEF2K inhibition also synergized with depletion of eukaryotic translation initiation factor 4E-binding protein 1 (eIF4EBP1; 4EBP1), a suppressor of eukaryotic protein translation initiation factor 4E (eIF4E), to induce c-MYC and Cyclin D1 expression, yet attenuate growth of TNBC cells. Proteomic analysis revealed that whereas eEF2K depletion alone uniquely induced Cyclin Dependent Kinase 1 (CDK1) and 6 (CDK6), combined depletion of eEF2K and 4EBP1 resulted in overlapping effects on the proteome, with the highest impact on the 'Collagen containing extracellular matrix' pathway (e.g. COL1A1), as well as the amino-acid transporter, SLC7A5/LAT1, suggesting a regulatory loop via mTORC1. In addition, combined depletion of eEF2K and 4EBP1 indirectly reduced the levels of IFN-dependent innate immune response-related factors. Thus, eEF2K inhibition triggers cell cycle arrest/death under unfavourable metabolic conditions such as Gln-starvation/GLS1 inhibition or 4EBP1 depletion, uncovering new therapeutic avenues for TNBC and underscoring a pressing need for clinically relevant eEF2K inhibitors.

Topics: Adaptor Proteins, Signal Transducing; Antineoplastic Combined Chemotherapy Protocols; Benzeneacetamides; Cell Cycle Proteins; Cell Line, Tumor; Cyclin D1; Cyclopentanes; Drug Synergism; Elongation Factor 2 Kinase; Female; Gene Silencing; Glutaminase; Humans; Protein Kinase Inhibitors; Proteins; Proto-Oncogene Proteins c-myc; Sulfides; Thiadiazoles; Triple Negative Breast Neoplasms

Triple-negative breast cancer (TNBC) is a highly metastatic and deadly disease. TNBC tumors lack estrogen receptor (ERα), progesterone receptor (PR), and HER2 (ErbB2) and exhibit increased glutamine metabolism, a requirement for tumor growth. The G protein-coupled kisspeptin receptor (KISS1R) is highly expressed in patient TNBC tumors and promotes malignant transformation of breast epithelial cells. This study found that TNBC patients displayed elevated plasma kisspeptin levels compared with healthy subjects. It also provides the first evidence that in addition to promoting tumor growth and metastasis in vivo, KISS1R-induced glutamine dependence of tumors. In addition, tracer-based metabolomics analyses revealed that KISS1R promoted glutaminolysis and nucleotide biosynthesis by increasing c-Myc and glutaminase levels, key regulators of glutamine metabolism. Overall, this study establishes KISS1R as a novel regulator of TNBC metabolism and metastasis, suggesting that targeting KISS1R could have therapeutic potential in the treatment of TNBC.

Topics: Adult; Aged; Animals; Carcinogenesis; Case-Control Studies; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cellular Reprogramming; Energy Metabolism; Female; Gene Expression Regulation, Neoplastic; Glutaminase; Glutamine; Humans; Mice, Inbred NOD; Mice, SCID; Middle Aged; Neoplasm Invasiveness; Nucleotides; Proto-Oncogene Proteins c-myc; Receptors, Kisspeptin-1; Signal Transduction; Triple Negative Breast Neoplasms; Tumor Burden; Young Adult

Glutamine serves as an important nutrient with many cancer types displaying glutamine dependence. Following cellular uptake glutamine is converted to glutamate in a reaction catalysed by mitochondrial glutaminase. This glutamate has many uses, including acting as an anaplerotic substrate (via alpha-ketoglutarate) to replenish TCA cycle intermediates. CB-839 is a potent, selective, orally bioavailable inhibitor of glutaminase that has activity in Triple receptor-Negative Breast Cancer (TNBC) cell lines and evidence of efficacy in advanced TNBC patients.. A panel of eleven breast cancer cell lines was used to investigate the anti-proliferative effects of the glutaminase inhibitors CB-839 and BPTES in different types of culture medium, with or without additional pyruvate supplementation. The abundance of the TCA cycle intermediate fumarate was quantified as a measure if TCA cycle anaplerosis. Pyruvate secretion by TNBC cultures was then assessed with or without AZD3965, a monocarboxylate transporter 1 (MCT1) inhibitor. Finally, two dimensional (2D) monolayer and three dimensional (3D) spheroid assays were used to compare the effect of microenvironmental growth conditions on CB-839 activity.. The anti-proliferative activity of CB-839 in a panel of breast cancer cell lines was similar to published reports, but with a major caveat; growth inhibition by CB-839 was strongly attenuated in culture medium containing pyruvate. This pyruvate-dependent attenuation was also observed with a related glutaminase inhibitor, BPTES. Studies demonstrated that exogenous pyruvate acted as an anaplerotic substrate preventing the decrease of fumarate in CB-839-treated conditions. Furthermore, endogenously produced pyruvate secreted by TNBC cell lines was able to act in a paracrine manner to significantly decrease the sensitivity of recipient cells to glutaminase inhibition. Suppression of pyruvate secretion using the MCT1 inhibitor AZD3965, antagonised this paracrine effect and increased CB-839 activity. Finally, CB-839 activity was significantly compromised in 3D compared with 2D TNBC culture models, suggesting that 3D microenvironmental features impair glutaminase inhibitor responsiveness.. This study highlights the potential influence that both circulating and tumour-derived pyruvate can have on glutaminase inhibitor efficacy. Furthermore, it highlights the benefits of 3D spheroid cultures to model the features of the tumour microenvironment and improve the in vitro investigation of cancer metabolism-targeted therapeutics.

Topics: Benzeneacetamides; Cell Proliferation; Drug Resistance, Neoplasm; Female; Glutaminase; Glutamine; Humans; Pyruvic Acid; Thiadiazoles; Triple Negative Breast Neoplasms; Tumor Cells, Cultured; Tumor Microenvironment

Triple-negative breast cancers (TNBCs) lack progesterone and estrogen receptors and do not have amplified human epidermal growth factor receptor 2, the main therapeutic targets for managing breast cancer. TNBCs have an altered metabolism, including an increased Warburg effect and glutamine dependence, making the glutaminase inhibitor CB-839 therapeutically promising for this tumor type. Accordingly, CB-839 is currently in phase I/II clinical trials. However, not all TNBCs respond to CB-839 treatment, and the tumor resistance mechanism is not yet fully understood. Here we classified cell lines as CB-839-sensitive or -resistant according to their growth responses to CB-839. Compared with sensitive cells, resistant cells were less glutaminolytic and, upon CB-839 treatment, exhibited a smaller decrease in ATP content and less mitochondrial fragmentation, an indicator of poor mitochondrial health. Transcriptional analyses revealed that the expression levels of genes linked to lipid metabolism were altered between sensitive and resistant cells and between breast cancer tissues (available from The Cancer Genome Atlas project) with low

Topics: Benzeneacetamides; Carnitine O-Palmitoyltransferase; Cell Movement; Cell Proliferation; Drug Resistance, Neoplasm; Female; Glutaminase; Glutamine; Humans; Oxidation-Reduction; Thiadiazoles; Triple Negative Breast Neoplasms; Tumor Cells, Cultured

Altered glycolytic flux in cancer cells (the "Warburg effect") causes their proliferation to rely upon elevated glutamine metabolism ("glutamine addiction"). This requirement is met by the overexpression of glutaminase C (GAC), which catalyzes the first step in glutamine metabolism and therefore represents a potential therapeutic target. The small molecule CB-839 was reported to be more potent than other allosteric GAC inhibitors, including the parent compound bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl (BPTES), and is in clinical trials. Recently, we described the synthesis of BPTES analogs having distinct saturated heterocyclic cores as a replacement for the flexible chain moiety, with improved microsomal stability relative to CB-839 and BPTES. Here, we show that one of these new compounds, UPGL00004, like CB-839, more potently inhibits the enzymatic activity of GAC, compared with BPTES. We also compare the abilities of UPGL00004, CB-839, and BPTES to directly bind to recombinant GAC and demonstrate that UPGL00004 has a similar binding affinity as CB-839 for GAC. We also show that UPGL00004 potently inhibits the growth of triple-negative breast cancer cells, as well as tumor growth when combined with the anti-vascular endothelial growth factor antibody bevacizumab. Finally, we compare the X-ray crystal structures for UPGL00004 and CB-839 bound to GAC, verifying that UPGL00004 occupies the same binding site as CB-839 or BPTES and that all three inhibitors regulate the enzymatic activity of GAC via a similar allosteric mechanism. These results provide insights regarding the potency of these inhibitors that will be useful in designing novel small-molecules that target a key enzyme in cancer cell metabolism.

Topics: Allosteric Site; Amino Acid Substitution; Antineoplastic Agents; Benzeneacetamides; Binding, Competitive; Cell Line, Tumor; Cell Proliferation; Crystallography, X-Ray; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Enzyme Inhibitors; Glutaminase; Glutamine; Humans; Hydrogen Bonding; Models, Molecular; Molecular Conformation; Mutation; Neoplasm Proteins; Recombinant Proteins; Sulfides; Thiadiazoles; Triple Negative Breast Neoplasms

Tumor cells display fundamental changes in metabolism and nutrient uptake in order to utilize additional nutrient sources to meet their enhanced bioenergetic requirements. Glutamine (Gln) is one such nutrient that is rapidly taken up by tumor cells to fulfill this increased metabolic demand. A vital step in the catabolism of glutamine is its conversion to glutamate by the mitochondrial enzyme glutaminase (GLS). This study has identified GLS a potential therapeutic target in breast cancer, specifically in the basal subtype that exhibits a deregulated glutaminolysis pathway. Using inducible shRNA mediated gene knockdown, we discovered that loss of GLS function in triple-negative breast cancer (TNBC) cell lines with a deregulated glutaminolysis pathway led to profound tumor growth inhibition in vitro and in vivo. GLS knockdown had no effect on growth and metabolite levels in non-TNBC cell lines. We rescued the anti-tumor effect of GLS knockdown using shRNA resistant cDNAs encoding both GLS isoforms and by addition of an α-ketoglutarate (αKG) analog thus confirming the critical role of GLS in TNBC. Pharmacological inhibition of GLS with the small molecule inhibitor CB-839 reduced cell growth and led to a decrease in mammalian target of rapamycin (mTOR) activity and an increase in the stress response pathway driven by activating transcription factor 4 (ATF4). Finally, we found that GLS inhibition synergizes with mTOR inhibition, which introduces the possibility of a novel therapeutic strategy for TNBC. Our study revealed that GLS is essential for the survival of TNBC with a deregulated glutaminolysis pathway. The synergistic activity of GLS and mTOR inhibitors in TNBC cell lines suggests therapeutic potential of this combination for the treatment of vulnerable subpopulations of TNBC.

Topics: Cell Line, Tumor; Female; Glutaminase; Glutamine; Humans; TOR Serine-Threonine Kinases; Triple Negative Breast Neoplasms

Glutamine metabolism is emerging as one aspect of dysregulated metabolism of tumors. Triple-negative breast cancer (TNBC) cells are glutamine dependent, whereas luminal-type cells tend to be glutamine independent. Therefore, TNBC patients might benefit from therapies targeting glutamine metabolism. To investigate the clinical significance of glutamine metabolism, we examined expression and prognostic significance of glutaminase in tumor cells and tumor-infiltrating lymphocytes (TILs) in TNBC. We retrieved 658 surgically resected TNBCs and analyzed glutaminase expression in tumor cells and TILs by immunohistochemical staining. Glutaminase expression was observed in 237 cases (36.0%) in tumor cells and 104 cases (15.5%) in TILs. Although glutaminase expression in tumor cells was significantly associated with a low level of TILs (p = 0.018), glutaminase expression in TILs was significantly higher in cases with a high level of TILs (p = 0.031). Glutaminase expression in tumor cells was significantly associated with poor disease-free survival in patients with lymph node metastasis and high levels of TILs (p = 0.020). In addition, it was an independent poor prognostic factor (hazard ratio = 10.643, 95% confidence interval = 1.999-56.668; p = 0.006). Glutaminase expression in tumor cells was observed in a subset of TNBC patients. It was significantly associated with a low level of TILs and poor disease-free survival in TNBCs presenting with lymph node metastasis and high levels of TILs.

Topics: Adult; Aged; Biomarkers, Tumor; Disease-Free Survival; Female; Glutaminase; Humans; Immunohistochemistry; Lymphatic Metastasis; Lymphocytes, Tumor-Infiltrating; Middle Aged; Prognosis; Proportional Hazards Models; Tissue Array Analysis; Triple Negative Breast Neoplasms

Glutamine provides cancer cells with the energy required to synthesize macromolecules. Methods which block glutamine metabolism in treatment of breast cancer inhibit oncogenic transformation and tumor growth. We investigated whether inhibiting glutamine metabolism produces effects that are synergistic with those produced by drugs which damage DNA in triple-negative breast cancer cells. HCC1937 and BT-549 breast cancer cells were co-treated with either cisplatin or etoposide in combination with BPTES (a specific inhibitor of glutaminase 1) or exposure to a glutamine-free medium, and the cell proliferation and cell apoptosis were measured by flow cytometry, immunoblotting studies, and CCK-8 assays. The results showed that both glutamine deprivation and BPTES pretreatments increased the toxic effects of cisplatin and etoposide on HCC1937 cells, as demonstrated by their reduced proliferation, increased expression of apoptosis-related proteins (cleaved-PARP, cleaved-caspase 9, and cleaved-caspase 3) and decreased Bcl-2/BAX ratio. However, in BT-549 cells, glutamine deprivation and BPTES treatment increased etoposide-induced apoptosis only when used with higher concentrations of etoposide, and the effect on cisplatin-induced apoptosis was minimal. These results suggest that the anti-cancer effects produced by a combined approach of inhibiting glutamine metabolism and administering common chemotherapeutic agents correlate with the tumor cell type and specific drugs being administered.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Cell Line, Tumor; Cell Survival; Cisplatin; Culture Media; Dose-Response Relationship, Drug; Etoposide; Female; Glutaminase; Glutamine; Humans; Immunoblotting; Sulfides; Thiadiazoles; Triple Negative Breast Neoplasms

Glutamine serves as an important source of energy and building blocks for many tumor cells. The first step in glutamine utilization is its conversion to glutamate by the mitochondrial enzyme glutaminase. CB-839 is a potent, selective, and orally bioavailable inhibitor of both splice variants of glutaminase (KGA and GAC). CB-839 had antiproliferative activity in a triple-negative breast cancer (TNBC) cell line, HCC-1806, that was associated with a marked decrease in glutamine consumption, glutamate production, oxygen consumption, and the steady-state levels of glutathione and several tricarboxylic acid cycle intermediates. In contrast, no antiproliferative activity was observed in an estrogen receptor-positive cell line, T47D, and only modest effects on glutamine consumption and downstream metabolites were observed. Across a panel of breast cancer cell lines, GAC protein expression and glutaminase activity were elevated in the majority of TNBC cell lines relative to receptor positive cells. Furthermore, the TNBC subtype displayed the greatest sensitivity to CB-839 treatment and this sensitivity was correlated with (i) dependence on extracellular glutamine for growth, (ii) intracellular glutamate and glutamine levels, and (iii) GAC (but not KGA) expression, a potential biomarker for sensitivity. CB-839 displayed significant antitumor activity in two xenograft models: as a single agent in a patient-derived TNBC model and in a basal like HER2(+) cell line model, JIMT-1, both as a single agent and in combination with paclitaxel. Together, these data provide a strong rationale for the clinical investigation of CB-839 as a targeted therapeutic in patients with TNBC and other glutamine-dependent tumors.

Topics: Administration, Oral; Animals; Antineoplastic Agents; Benzeneacetamides; Cell Line, Tumor; Dose-Response Relationship, Drug; Enzyme Inhibitors; Female; Glutaminase; Humans; Mammary Neoplasms, Experimental; Mice; Mice, SCID; Middle Aged; Neoplasms, Basal Cell; Sulfides; Thiadiazoles; Triple Negative Breast Neoplasms; Xenograft Model Antitumor Assays