glutaminase and Melanoma

To evaluate the in vitro activity of polyethylene glycol-conjugated L-asparaginase (PEG-Lasparaginase) against fresh human tumor specimens, using the human tumor clonogenic assay (HTCA), and to perform a phase I dose-escalation clinical trial of PEG-L-asparaginase. The goal of the clinical study was to determine the toxicity and optimum biologic dose of PEG-L-asparaginase based on depletion of serum L-asparagine in patients with advanced solid tumors.. A modified method for determination of serum L-asparagine is described. PEG-L-asparaginase was administered by intramuscular injection every 2 weeks to 28 patients with various types of advanced solid tumor malignancies. At least 3 patients were evaluated at each dose level: 250 IU/m2, 500 IU/m2, 1,000 IU/m2, 1,500 IU/m2, 2,000 IU/m2.. The in vitro HTCA studies suggested good antitumor activity against malignant melanoma and multiple myeloma. Serum L-asparagine was most consistently and profoundly depleted (up to 4 weeks) in patients treated with 2,000 IU/m2. Patients receiving this dose level also showed more frequent grade 1, grade 2, and occasional grade 3 toxicities of fatigue/weakness, nausea/vomiting, and anorexia/ weight loss. Three patients developed hypersensitivity reactions, but these were not dose related. Two patients developed deep vein thromboses. We saw no episodes of clinical pancreatitis, but there were minor fluctuations of serum amylase and lipase. We saw no partial or complete responses in patients treated in this study, including 11 patients with malignant melanoma.. We conclude that PEG-L-asparaginase is generally well tolerated in patients with advanced solid tumors, and a dosage of 2,000 IU/m2 by intramuscular injection every 2 weeks results in significant depletion of serum L-asparagine.

Topics: Adult; Antineoplastic Agents; Asparaginase; Asparagine; Carcinoma, Non-Small-Cell Lung; Drug Screening Assays, Antitumor; Glutaminase; Humans; Lung Neoplasms; Melanoma; Neoplasm Proteins; Neoplasms; Polyethylene Glycols; Skin Neoplasms

STAG2, an important subunit in cohesion complex, is involved in the segregation of chromosomes during the late mitosis and the formation of sister chromatids. Mutational inactivation of STAG2 is a major cause of the resistance of BRAF-mutant melanomas to BRAF/MEK inhibitors. In the present study, we found that STAG2 was frequently down-regulated in thyroid cancers compared with control subjects. By a series of in vitro and in vivo studies, we demonstrated that STAG2 knockdown virtually had no effect on malignant phenotypes of BRAF-mutant thyroid cancer cells such as cell proliferation, colony formation and tumorigenic ability in nude mice compared with the control. In addition, unlike melanoma, STAG2 knockdown also did not affect the sensitivity of these cells to MEK inhibitor. However, we surprisingly found that STAG2-knockdown cells exhibited more sensitive to glutamine deprivation or glutaminase inhibitor BPTES compared with control cells. Mechanistically, knocking down STAG2 in BRAF-mutant thyroid cancer cells decreases the protein stability of c-Myc via the ERK/AKT/GSK3β feedback pathway, thereby impairing glutamine metabolism of thyroid cancer cells by down-regulating its downstream targets such as SCL1A5, GLS and GLS2. Our data, taken together, demonstrate that STAG2 inactivation reprograms glutamine metabolism of BRAF-mutant thyroid cancer cells, thereby improving their cellular response to glutaminase inhibitor. This study will provide a potential therapeutic strategy for BRAF-mutant thyroid cancers.

Topics: Animals; Cell Cycle Proteins; Cell Line, Tumor; Glutaminase; Glutamine; Humans; Melanoma; Mice; Mice, Nude; Mitogen-Activated Protein Kinase Kinases; Mutation; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; Thyroid Neoplasms

Melanoma is a kind of aggressive skin neoplasms with high mortality. The purpose of this present research was to investigate the effects and potential mechanisms of long-noncoding RNA (lncRNA) MSC antisense RNA 1 (MSC-AS1) in melanoma. MSC-AS1, miR-330-3p and YAP1 expression levels in melanoma tissues and cells were assessed by quantitative real-time polymerase chain reaction. Melanoma cells were evaluated using cell count kit-8, clone formation and ELISA in vitro . The relationship among MSC-AS1, YAP1 and miR-330-3p was validated by pull-down and luciferase reporter assays. Finally, the role of MSC-AS1 in vivo was determined by the xenograft model. Results showed that lncRNA MSC-AS1 was upregulated in melanoma tissues and cells. High expression of MAS-AS1 was positively correlated with a poor prognosis. Pull-down and luciferase reporter demonstrated that miR-330-3p specifically binds directly to YAP1 and MSC-AS1, respectively. MSC-AS1 promoted the expression of YAP1 by downregulating miR-330-3p. Functional experiments suggested that knockdown of MSC-AS1 suppressed the proliferation of melanoma cells and decreased the levels of glutamine, glutamate and α-ketoglutarate, glutaminase and glutamine transporter alanine-serine-cysteine transporter 2. Upregulation of miR-330-3p alleviated the promotion effect of MSC-AS1 overexpression on the proliferation and glutaminolysis of melanoma cells. The above changes could be reversed by YAP1 overexpression. In addition, knockdown of MSC-AS1 dramatically restrained the growth of melanoma cells in xenograft model. In conclusion, our results revealed that MSC-AS1 facilitated the proliferation and glutaminolysis of melanoma cells by regulating miR-330-3p/ YAP1 pathway, suggesting that MSC-AS1 could provide a new idea for the treatment of melanoma.

Topics: Alanine; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cysteine; Gene Expression Regulation, Neoplastic; Glutamates; Glutaminase; Glutamine; Humans; Ketoglutaric Acids; Melanoma; MicroRNAs; Oncogenes; RNA, Long Noncoding; Serine; YAP-Signaling Proteins

Immune-checkpoint inhibitors and adoptive tumor-infiltrating lymphocyte (TIL) therapies have profoundly improved the survival of patients with melanoma. However, a majority of patients do not respond to these agents, and many responders experience disease relapse. Although numerous innovative treatments are being explored to offset the limitations of these agents, novel therapeutic combinations with immunotherapies have the potential to improve patient responses. In this study, we evaluated the antimelanoma activity of immunotherapy combinations with Telaglenastat (CB-839), a potent glutaminase inhibitor (GLSi) that has favorable systemic tolerance. In

Topics: Animals; Glutaminase; Humans; Immune Checkpoint Inhibitors; Immunotherapy; Melanoma; Mice; T-Lymphocytes; Tumor Microenvironment

Vascular endothelial growth factor receptor 2 (VEGFR2) activating mutations are emerging as important oncogenic driver events. Understanding the biological implications of such mutations may help to pinpoint novel therapeutic targets. Here we show that activated VEGFR2 via the pro-oncogenic R1051Q mutation induces relevant metabolic changes in melanoma cells. The expression of VEGFR2

Topics: Adenosine Triphosphate; Antineoplastic Agents; Cell Line, Tumor; Energy Metabolism; Enzyme Inhibitors; Gain of Function Mutation; Glutaminase; Glutamine; Humans; Melanoma; Signal Transduction; Skin Neoplasms; Vascular Endothelial Growth Factor Receptor-2

Aberrant glutamatergic signaling has been implicated in altered metabolic activity in many cancer types, including malignant melanoma. Previously, we have illustrated the role of metabotropic glutamate receptor 1 (GRM1) in neoplastic transformation of melanocytes

Topics: Animals; Apoptosis; Benzeneacetamides; Biological Availability; Cell Proliferation; Drug Therapy, Combination; Female; Glutamic Acid; Glutaminase; Humans; Melanoma; Mice; Mice, Hairless; Neuroprotective Agents; Receptors, Metabotropic Glutamate; Riluzole; Signal Transduction; Thiadiazoles; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Glutamine catabolism is considered to be an important metabolic pathway for cancer cells. Glutaminase (GLS) is the important rate-limiting enzyme of glutamine catabolism. miR-137 functions as a tumor suppressor in many human malignant tumors. However, the role and molecular mechanism of miR-137 and GLS in malignant melanoma has not been reported. In this study, we showed that miR-137 was decreased in melanoma tissue, and the low miR-137 level and high GLS expression are independent risk factor in melanoma. miR-137 suppressed the proliferation and glutamine catabolism of melanoma cells. GLS is crucial for glutamine catabolism and growth of malignant melanoma. We also demonstrated that miR-137 acts as a tumor suppressor in melanoma by targeting GLS. This result elucidates a new mechanism for miR-137 in melanoma development and provides a survival indicator and potential therapeutic target for melanoma patients.

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Glutaminase; Glutamine; Heterografts; Humans; Melanoma; Mice; Mice, Nude; MicroRNAs; Prognosis; Skin Neoplasms

Malignant melanoma (MM) is an aggressive malignancy, which accounts for 80% of skin cancer-related deaths and is notably resistant to conventional chemotherapeutic agents. One of the most common treatments for melanoma is surgery, followed by various combinations of chemotherapy drugs.. To investigate the role of microRNA (miR)-203 in sensitivity of MM cells to the chemotherapy drug temozolomide (TMZ).. Using quantitative reverse transcription PCR, we measured the expression of miR-203 in an MM cell line. Cell viability of MM cells in response to TMZ treatment was measured by MTT assay. Glutamine metabolism and level of glutaminase (GLS) were assessed.. We found that miR-203 was significantly downregulated by TMZ treatment in human MM cells. In addition, miR-203 expression was lower in TMZ-resistant MM cells compared with parental cells. Interestingly, glutamine metabolism and GLS expression were higher in TMZ-resistant cells, and TMZ-resistant cells exhibited more glutamine dependency than TMZ-sensitive MM cells. We also identified GLS as a downstream target gene of miR-203, which binds directly to the 3' untranslated region of GLS. Overexpression of miR-203 was associated with decreased GLS expression and sensitization to TMZ in vitro. Re-expression of GLS in miR-203 overexpressing MM cells markedly rescued miR-203-mediated suppression of these events. Finally, we found a significant negative correlation between miR-203 and GL, with downregulation of miR-203 and upregulation of GLS in tissues from patients with MM.. Taken together, our results demonstrate that overexpression of miR-203 sensitizes MM cells to TMZ by targeting GLS, providing new insights into the development of anti-tumour agents for patients with chemotherapy-resistant MM.

Topics: Antineoplastic Agents, Alkylating; Cell Line, Tumor; Dacarbazine; Down-Regulation; Drug Resistance, Neoplasm; Glutaminase; Glutamine; Humans; Melanoma; MicroRNAs; Temozolomide

Tumours display different cell populations with distinct metabolic phenotypes. Thus, subpopulations can adjust to different environments, particularly with regard to oxygen and nutrient availability. Our results indicate that progression to metastasis requires mitochondrial function. Our research, centered on cell lines that display increasing degrees of malignancy, focused on metabolic events, especially those involving mitochondria, which could reveal which stages are mechanistically associated with metastasis. Melanocytes were subjected to several cycles of adhesion impairment, producing stable cell lines exhibiting phenotypes representing a progression from non-tumorigenic to metastatic cells. Metastatic cells (4C11+) released the highest amounts of lactate, part of which was derived from glutamine catabolism. The 4C11+ cells also displayed an increased oxidative metabolism, accompanied by enhanced rates of oxygen consumption coupled to ATP synthesis. Enhanced mitochondrial function could not be explained by an increase in mitochondrial content or mitochondrial biogenesis. Furthermore, 4C11+ cells had a higher ATP content, and increased succinate oxidation (complex II activity) and fatty acid oxidation. In addition, 4C11+ cells exhibited a 2-fold increase in mitochondrial membrane potential (ΔΨmit). Consistently, functional assays showed that the migration of cells depended on glutaminase activity. Metabolomic analysis revealed that 4C11+ cells could be grouped as a subpopulation with a profile that was quite distinct from the other cells investigated in the present study. The results presented here have centred on how the multiple metabolic inputs of tumour cells may converge to compose the so-called metastatic phenotype.

Topics: Animals; Cell Line, Tumor; Cell Movement; Glucose; Glutaminase; Glutamine; Lactates; Melanocytes; Melanoma; Membrane Potentials; Metabolism; Mice; Oxidation-Reduction; Oxidative Phosphorylation; Oxygen Consumption; Phenotype

(V600) BRAF mutations drive approximately 50% of metastatic melanoma which can be therapeutically targeted by BRAF inhibitors (BRAFi) and, based on resistance mechanisms, the combination of BRAF and MEK inhibitors (BRAFi + MEKi). Although the combination therapy has been shown to provide superior clinical benefits, acquired resistance is still prevalent and limits the overall survival benefits. Recent work has shown that oncogenic changes can lead to alterations in tumor cell metabolism rendering cells addicted to nutrients, such as the amino acid glutamine. Here, we evaluated whether melanoma cells with acquired resistance display glutamine dependence and whether glutamine metabolism can be a potential molecular target to treat resistant cells.. Isogenic BRAFi sensitive parental (V600) BRAF mutant melanoma cell lines and resistant (derived by chronic treatment with vemurafenib) sub-lines were used to assess differences in the glutamine uptake and sensitivity to glutamine deprivation. To evaluate a broader range of resistance mechanisms, isogenic pairs where the sub-lines were resistant to BRAFi + MEKi were also studied. Since resistant cells demonstrated increased sensitivity to glutamine deficiency, we used glutaminase inhibitors BPTES [bis-2-(5 phenylacetamido-1, 2, 4-thiadiazol-2-yl) ethyl sulfide] and L-L-DON (6-Diazo-5-oxo-L-norleucine) to treat MAPK pathway inhibitor (MAPKi) resistant cell populations both in vitro and in vivo.. We demonstrated that MAPKi-acquired resistant cells uptook greater amounts of glutamine and have increased sensitivity to glutamine deprivation than their MAPKi-sensitive counterparts. In addition, it was found that both BPTES and L-DON were more effective at decreasing cell survival of MAPKi-resistant sub-lines than parental cell populations in vitro. We also showed that mutant NRAS was critical for glutamine addiction in mutant NRAS driven resistance. When tested in vivo, we found that xenografts derived from resistant cells were more sensitive to BPTES or L-DON treatment than those derived from parental cells.. Our study is a proof-of-concept for the potential of targeting glutamine metabolism as an alternative strategy to suppress acquired MAPKi-resistance in melanoma.

Topics: Animals; Cell Line, Tumor; Cellular Reprogramming; Drug Resistance, Neoplasm; Enzyme Inhibitors; Gene Knockdown Techniques; Glutaminase; Glutamine; GTP Phosphohydrolases; Humans; Indoles; Melanoma; Membrane Proteins; Mice, Inbred NOD; Mice, SCID; Sulfonamides; Vemurafenib

The protein content and the activity and type of phosphate-dependent glutaminase were determined in freshly pigmented lesions obtained from human melanoma and adjacent skin. Significant phosphate-dependent glutaminase activity was found in both the melanoma and non-pigmented adjacent skin areas. A comparison between the pigmented and adjacent skin areas suggests the occurrence of gradual metabolic changes that result in an increased protein content in the centre of the neoplasia. The presence of a kidney-type glutaminase (K(m) of 2-5 mm) indicates a high sensitivity of the melanoma to variations in glutamine plasma levels (0.6 to 1 mm). These data lead us to postulate that glutamine supply is an important factor for melanoma cell proliferation, being a source of nitrogen for DNA and RNA synthesis. The intense neovascularization observed in melanoma ensures the oxygen supply that is required for glutamine oxidation. These findings support the proposition that glutamine is an important fuel for melanoma.

Topics: Glutaminase; Humans; Melanoma; Prognosis; Skin Neoplasms