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1.
Clin Cancer Res ; 2024 Mar 27.
Article in English | MEDLINE | ID: mdl-38536082

ABSTRACT

PURPOSE: Majority of patients with metastatic prostate cancer who receive androgen deprivation therapy and androgen receptor (AR) signaling inhibitors progress. Activation of the glucocorticoid receptor (GR) is associated with ARSI-resistance. This single-arm phase I trial assessed safety and pharmacokinetic feasibility of combined AR antagonist (enzalutamide) and selective GR modulator (relacorilant) in metastatic castration-resistant prostate cancer (mCRPC) patients. PATIENTS AND METHODS: This was a phase I trial (NCT03674814) of relacorilant and enzalutamide in refractory mCRPC patients enrolled using 6+3 design. Enzalutamide dose was kept constant at 120 mg/day with escalating doses of relacorilant based on safety and pharmacokinetic measures in cohorts of ≥ 6 patients. Primary objective was safety and establishment of pharmacologically active doses. Secondary objectives were related to antitumor activity. RESULTS: Thirty-five mCRPC patients were enrolled. Twenty-three were accrued across 3 dose cohorts in the dose escalation phase and twelve enrolled at the recommended phase 2 dose. The combination was generally well-tolerated and safe and achieved desirable enzalutamide pharmacokinetics. RP2D of 120 mg/day + 150 mg/day respectively was established. Median time on study was 2.2 months with 4 patients remaining on study for longer than 11 months. Four of twelve evaluable patients had a PSA partial response. CONCLUSIONS: This is the first prospective trial combining an AR antagonist and a non-steroidal selective GR modulator. The combination was safe and well tolerated with PSA response and prolonged disease control observed in a limited subset of patients. Further prospective trials are justified to evaluate efficacy and identify predictive biomarkers of response.

2.
Biomedicines ; 12(1)2024 Jan 16.
Article in English | MEDLINE | ID: mdl-38255301

ABSTRACT

NKG2D is an activating receptor expressed by all human NK cells and CD8 T cells. Harnessing the NKG2D/NKG2D ligand axis has emerged as a viable avenue for cancer immunotherapy. However, there is a long-standing controversy over whether soluble NKG2D ligands are immunosuppressive or immunostimulatory, originating from conflicting data generated from different scopes of pre-clinical investigations. Using multiple pre-clinical tumor models, we demonstrated that the impact of the most characterized human solid tumor-associated soluble NKG2D ligand, the soluble MHC I chain-related molecule (sMIC), on tumorigenesis depended on the tumor model being studied and whether the tumor cells possessed stemness-like properties. We demonstrated that the potential of tumor formation or establishment depended upon tumor cell stem-like properties irrespective of tumor cells secreting the soluble NKG2D ligand sMIC. Specifically, tumor formation was delayed or failed if sMIC-expressing tumor cells expressed low stem-cell markers; tumor formation was rapid if sMIC-expressing tumor cells expressed high stem-like cell markers. However, once tumors were formed, overexpression of sMIC unequivocally suppressed tumoral NK and CD8 T cell immunity and facilitated tumor growth. Our study distinguished the differential impacts of soluble NKG2D ligands in tumor formation and tumor progression, cleared the outstanding controversy over soluble NKG2D ligands in modulating tumor immunity, and re-enforced the viability of targeting soluble NKG2D ligands for cancer immunotherapy for established tumors.

3.
Curr Treat Options Oncol ; 25(3): 293-312, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38291265

ABSTRACT

OPINION STATEMENT: Treatment for metastatic hormone-sensitive prostate cancer has undergone significant evolution in recent years, leading to substantial improvements in overall survival. Men are living longer than ever before with a median survival now which is almost 6 years. The timing and extent of metastatic disease combined with individual patient factors helps treatment recommendation of doublet therapy including androgen deprivation (ADT) plus either chemotherapy or androgen receptor signaling inhibition (ARSI) or triplet therapy with ADT+ARSI+chemotherapy. New treatments must continue to be developed to enhance survival with goals of cure. Better biomarkers that allow for more effective treatments will enhance disease control, quality of life, and survival.


Subject(s)
Prostatic Neoplasms , Male , Humans , Prostatic Neoplasms/therapy , Androgen Antagonists/therapeutic use , Quality of Life , Treatment Outcome , Hormones/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/adverse effects
6.
JAMA Oncol ; 9(10): 1441-1446, 2023 Oct 01.
Article in English | MEDLINE | ID: mdl-37651124

ABSTRACT

Importance: Although the combination of nivolumab plus ipilimumab has unquestionable benefit over nivolumab monotherapy in advanced melanoma, currently no summative analyses have compared the combination with nivolumab monotherapy for advanced cancers other than melanoma. Objective: To examine whether the addition of ipilimumab to standard-dose nivolumab safely improves clinical outcomes in patients with advanced cancers other than melanoma. Data Sources: Electronic databases (PubMed, EBSCO Information Services, Embase, and Cochrane Library) were systematically searched for studies of standard-dose nivolumab plus ipilimumab vs nivolumab alone in the treatment of advanced cancers other than melanoma published from database inception to October 31, 2022. Study Selection: Eight studies (total patients, 1727; nivolumab plus ipilimumab group, 854; nivolumab monotherapy group, 873) met the selection criteria. Patients had squamous cell lung cancer, non-small cell lung cancer with programmed death ligand 1 level of 1% or higher, small cell lung cancer, pleural mesothelioma, urothelial carcinoma, esophagogastric carcinoma, sarcoma, or glioblastoma multiforme. Data Extraction and Synthesis: For comparison of overall survival (OS) and progression-free survival (PFS) outcomes, estimation of log(hazard ratios [HRs]) and SEs was initially performed for OS and PFS of each included study based on summary statistics extracted from individual Kaplan-Meier curves. Inverse-variance weighting was then used to compute pooled HRs (95% CIs). For comparison of dichotomous data (treatment-related grade 3 to 4 adverse events and discontinuations), odds ratios (ORs) were used, and the Mantel-Haenszel method was used to estimate pooled ORs (95% CIs). Results: Treatment with nivolumab plus ipilimumab was not associated with improvement in OS over treatment with nivolumab alone (pooled HR, 0.95; 95% CI, 0.85-1.06; P = .36), with 4 of the 8 studies having numerically lower median OS with the combination. Nivolumab plus ipilimumab combination therapy was associated with marginal, but not clinically meaningful, improvement in PFS over nivolumab alone (pooled HR, 0.88; 95% CI, 0.79-0.98; P = .02). The combination was associated with substantially higher treatment-related grade 3 to 4 adverse events (pooled OR, 1.84; 95% CI, 1.47-2.31; P < .001) and treatment-related discontinuations (pooled OR, 1.96; 95% CI, 1.44-2.65; P < .001). This finding was recapitulated in meta-analyses of individual grade 3 to 4 adverse events of hepatotoxicity, gastrointestinal toxicity, pneumonitis, endocrine dysfunction, dermatitis, fatigue. Conclusions and Relevance: In this meta-analysis of 8 advanced cancers other than melanoma, the differences detected in OS and PFS between nivolumab plus ipilimumab and nivolumab were not clinically meaningful (even though statistical significance was detected in PFS). Treatment-related higher-grade toxicity and discontinuations were substantially higher with the combination therapy. The data indicate that investigations of anti-programmed death 1 (PD1) plus anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) therapies in any nonmelanoma advanced cancer should be conducted along with anti-PD1 monotherapy to ensure that the net effect of the addition of anti-CTLA-4 to anti-PD1 can be clearly established for that cancer and setting and that unnecessary CTLA-4 inhibition with related toxic effects (both clinical and financial) can be avoided.

7.
Oncotarget ; 14: 622-636, 2023 06 19.
Article in English | MEDLINE | ID: mdl-37335291

ABSTRACT

BACKGROUND: Androgen deprivation therapy (ADT) can lead to metabolic syndrome (MS) and is implicated in ADT-resistance. Metformin showed antineoplastic activity through mTOR inhibition secondary AMPK-activation. MATERIALS AND METHODS: To investigate whether metformin mitigated ADT-related MS, we conducted a randomized double-blind phase II trial of metformin 500 mg TID or placebo in non-diabetic patients with biochemically-relapsed or advanced PC due for ADT. Fasting serum glucose, insulin, PSA, metformin, weight and waist circumference (WC) were measured at baseline, week 12 and 28. The primary endpoint was a group of MS metrics. Secondary endpoints include PSA response, safety, serum metformin concentrations and analysis of downstream an mTOR target, phospho-S6-kinase. RESULTS: 36 men were randomized to either metformin or placebo. Mean age was 68.4. Mean weight, WC and insulin levels increased in both arms. At week 12 and 28, no statistical differences in weight, WC or insulin were observed in either arm. No significant difference in percentage of patients with PSA <0.2 at week 28 between metformin (45.5%) vs. placebo (46.7%). Analysis in the metformin-arm showed variable down-regulation of phospho-S6 kinase. CONCLUSIONS: In our small study, metformin added to ADT did not show a reduced risk of ADT-related MS or differences in PSA response.


Subject(s)
Insulins , Metabolic Syndrome , Metformin , Prostatic Neoplasms , Male , Humans , Aged , Prostatic Neoplasms/therapy , Androgen Antagonists/adverse effects , Metformin/adverse effects , Androgens , Prostate-Specific Antigen , Metabolic Syndrome/chemically induced , Metabolic Syndrome/prevention & control , Metabolic Syndrome/drug therapy , Insulins/therapeutic use
8.
Eur Urol Focus ; 9(3): 407-408, 2023 05.
Article in English | MEDLINE | ID: mdl-36707276

ABSTRACT

Intermittent androgen deprivation therapy in patients with prostate cancer and biochemical relapse does not prolong survival or improve quality of life.


Subject(s)
Prostatic Neoplasms , Male , Humans , Androgen Antagonists/adverse effects , Androgens , Quality of Life , Neoplasm Recurrence, Local/drug therapy , Chronic Disease
9.
NPJ Breast Cancer ; 8(1): 32, 2022 Mar 14.
Article in English | MEDLINE | ID: mdl-35288585

ABSTRACT

Patients with breast cancer frequently experience financial hardship, often due to the high costs of anti-cancer drugs. We sought to develop alternative trastuzumab dosing strategies, compare their pharmacokinetic effectiveness to standard dosing, and assess the expected financial implications of transitioning to them. We extracted clinical data from the records of 135 retrospectively identified patients with HER2-positive early breast cancer at a single, urban comprehensive cancer center who were treated with trastuzumab between 2017 and 2019. We performed pharmacokinetic simulations on a range of trastuzumab dose levels and frequencies, assessing efficacy by trough trastuzumab concentration (Ctrough) and population and individual likelihoods of Ctrough exceeding trastuzumab minimum effective concentration (MEC). We performed deterministic financial modeling to estimate the treatment-associated financial savings from alternative dosing strategies. Trastuzumab maintenance doses of 4 mg/kg every 3 weeks (Q3W) and 6 mg/kg every 4 weeks (Q4W) had nearly identical probabilities of Ctrough being above MEC as standard of care 6 mg/kg every 3 weeks. In the primary financial analysis, both trastuzumab 4 mg/kg Q3W and 6 mg/kg Q4W were associated with significant drug- and administration-related out-of-pocket cost savings over the duration of therapy, ranging from $765 (neoadjuvant, Q4W) to $2791 (adjuvant, Q4W). In particular, Q4W trastuzumab increased savings related to lost wages and travel cost avoidance. Low-dose and reduced frequency trastuzumab in appropriately selected patients may significantly reduce total drug utilization and meaningfully reduce patient financial toxicity. Prospective clinical trials evaluating low-dose or reduced-frequency administration of therapeutic monoclonal antibodies are warranted and needed.

10.
Clin Cancer Res ; 28(8): 1549-1559, 2022 04 14.
Article in English | MEDLINE | ID: mdl-35110415

ABSTRACT

PURPOSE: Although androgen deprivation therapy (ADT) and androgen receptor (AR) signaling inhibitors are effective in metastatic prostate cancer, resistance occurs in most patients. This phase I/II trial assessed the safety, pharmacokinetic impact, and efficacy of the glucocorticoid receptor (GR) antagonist mifepristone in combination with enzalutamide for castration-resistant prostate cancer (CRPC). PATIENTS AND METHODS: One hundred and six patients with CRPC were accrued. Phase I subjects were treated with enzalutamide monotherapy at 160 mg per day for 28 days to allow steady-state accumulation. Patients then entered the dose escalation combination portion of the study. In phase II, patients were randomized 1:1 to either receive enzalutamide alone or enzalutamide plus mifepristone. The primary endpoint was PSA progression-free survival (PFS), with radiographic PFS, and PSA response rate (RR) as key secondary endpoints. Circulating tumor cells were collected before randomization for exploratory translational biomarker studies. RESULTS: We determined a 25% dose reduction in enzalutamide, when added to mifepristone, resulted in equivalent drug levels compared with full-dose enzalutamide and was well tolerated. However, the addition of mifepristone to enzalutamide following a 12-week enzalutamide lead-in did not delay time to PSA, radiographic or clinical PFS. The trial was terminated early due to futility. CONCLUSIONS: This is the first prospective trial of dual AR-GR antagonism in CRPC. Enzalutamide combined with mifepristone was safe and well tolerated but did not meet its primary endpoint. The development of more specific GR antagonists combined with AR antagonists, potentially studied in an earlier disease state, should be explored.


Subject(s)
Prostatic Neoplasms, Castration-Resistant , Androgen Antagonists/therapeutic use , Androgen Receptor Antagonists/adverse effects , Benzamides , Humans , Male , Mifepristone/adverse effects , Nitriles , Phenylthiohydantoin , Prospective Studies , Prostate-Specific Antigen , Prostatic Neoplasms, Castration-Resistant/pathology , Receptors, Glucocorticoid
11.
Leukemia ; 35(9): 2672-2683, 2021 09.
Article in English | MEDLINE | ID: mdl-33658659

ABSTRACT

Anti-PD-1 monoclonal antibodies yield high response rates in patients with relapsed/refractory classic Hodgkin lymphoma (cHL), but most patients will eventually progress. Allogeneic hematopoietic cell transplantation (alloHCT) after PD-1 blockade may be associated with increased toxicity, raising challenging questions about the role, timing, and optimal method of transplantation in this setting. To address these questions, we assembled a retrospective cohort of 209 cHL patients who underwent alloHCT after PD-1 blockade. With a median follow-up among survivors of 24 months, the 2-year cumulative incidences (CIs) of non-relapse mortality and relapse were 14 and 18%, respectively; the 2-year graft-versus-host disease (GVHD) and relapse-free survival (GRFS), progression-free survival (PFS), and overall survival were 47%, 69%, and 82%, respectively. The 180-day CI of grade 3-4 acute GVHD was 15%, while the 2-year CI of chronic GVHD was 34%. In multivariable analyses, a longer interval from PD-1 to alloHCT was associated with less frequent severe acute GVHD, while additional treatment between PD-1 and alloHCT was associated with a higher risk of relapse. Notably, post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis was associated with significant improvements in PFS and GRFS. While awaiting prospective clinical trials, PTCy-based GVHD prophylaxis may be considered the optimal transplantation strategy for this patient population.


Subject(s)
Drug Resistance, Neoplasm , Hematopoietic Stem Cell Transplantation/mortality , Hodgkin Disease/therapy , Immune Checkpoint Inhibitors/adverse effects , Neoplasm Recurrence, Local/therapy , Programmed Cell Death 1 Receptor/antagonists & inhibitors , Salvage Therapy , Adolescent , Adult , Aged , Female , Follow-Up Studies , Hodgkin Disease/drug therapy , Hodgkin Disease/pathology , Humans , Male , Middle Aged , Neoplasm Recurrence, Local/drug therapy , Neoplasm Recurrence, Local/pathology , Prognosis , Retrospective Studies , Survival Rate , Transplantation, Homologous , Young Adult
12.
Blood Adv ; 5(6): 1648-1659, 2021 03 23.
Article in English | MEDLINE | ID: mdl-33710337

ABSTRACT

Autologous stem cell transplantation (ASCT) can be curative for patients with relapsed/refractory Hodgkin lymphoma (HL). Based on studies suggesting that anti-PD-1 monoclonal antibodies (mAbs) can sensitize patients to subsequent chemotherapy, we hypothesized that anti-PD-1 therapy before ASCT would result in acceptable outcomes among high-risk patients who progressed on or responded insufficiently to ≥1 salvage regimen, including chemorefractory patients who are traditionally considered poor ASCT candidates. We retrospectively identified 78 HL patients who underwent ASCT after receiving an anti-PD-1 mAb (alone or in combination) as third-line or later therapy across 22 centers. Chemorefractory disease was common, including 42 patients (54%) refractory to ≥2 consecutive systemic therapies immediately before anti-PD-1 treatment. Fifty-eight (74%) patients underwent ASCT after anti-PD-1 treatment, while 20 patients (26%) received additional therapy after PD-1 blockade and before ASCT. Patients received a median of 4 systemic therapies (range, 3-7) before ASCT, and 31 patients (41%) had a positive pre-ASCT positron emission tomography (PET) result. After a median post-ASCT follow-up of 19.6 months, the 18-month progression-free survival (PFS) and overall survival were 81% (95% CI, 69-89) and 96% (95% confidence interval [CI], 87-99), respectively. Favorable outcomes were observed for patients who were refractory to 2 consecutive therapies immediately before PD-1 blockade (18-month PFS, 78%), had a positive pre-ASCT PET (18-month PFS, 75%), or received ≥4 systemic therapies before ASCT (18-month PFS, 73%), while PD-1 nonresponders had inferior outcomes (18-month PFS, 51%). In this high-risk cohort, ASCT after anti-PD-1 therapy was associated with excellent outcomes, even among heavily pretreated, previously chemorefractory patients.


Subject(s)
Hematopoietic Stem Cell Transplantation , Hodgkin Disease , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Hodgkin Disease/drug therapy , Humans , Neoplasm Recurrence, Local/drug therapy , Retrospective Studies , Transplantation, Autologous
13.
Cancer J ; 26(4): 330-334, 2020.
Article in English | MEDLINE | ID: mdl-32732676

ABSTRACT

The increasing cost of health care is a major challenge around the world, but particularly in the United States. One reason for increased costs is the rapidly rising cost of oncology drugs. Potential solutions to this problem involve broad changes to health policy. However, an alternative solution is the development of lower-cost off-label treatment regimens, based on pharmacologic rationale, with significant potential economic impact. The pharmacologic and clinical properties of many drugs allow for a variety of different strategies. We describe this approach of interventional pharmacoeconomics and provide multiple individual examples.


Subject(s)
Economics, Pharmaceutical/standards , Humans
14.
Clin Pharmacol Ther ; 108(3): 487-493, 2020 09.
Article in English | MEDLINE | ID: mdl-32298471

ABSTRACT

Cancer care's sustainability is challenged by drug expenditures. In the absence of systemic change, innovation is needed to curtail drug costs. Interventional pharmacoeconomics (IVPE) utilizes clinical research to identify safe, efficacious, cost-conscious dosing regimens to extract maximum value from expensive therapies. Strategies include de-escalation of dosage, treatment duration and administration frequency, and substitution with therapeutic alternatives. In this review, we discuss how IVPE strategies have been successfully used and could be implemented going forward.


Subject(s)
Antineoplastic Agents/economics , Antineoplastic Agents/therapeutic use , Drug Costs , Neoplasms/drug therapy , Neoplasms/economics , Antineoplastic Agents/adverse effects , Antineoplastic Agents/pharmacokinetics , Cost Savings , Cost-Benefit Analysis , Drug Utilization/economics , Economics, Pharmaceutical , Humans , Quality Indicators, Health Care/economics , Value-Based Health Insurance/economics
15.
Thorac Surg Clin ; 30(2): 137-146, 2020 May.
Article in English | MEDLINE | ID: mdl-32327172

ABSTRACT

The treatment of patients with advanced non-small cell lung cancer with anaplastic lymphoma kinase chromosomal rearrangements has been revolutionized by the development of tyrosine kinase inhibitors (TKIs). Excellent progress has been made over the past decade, with 4 TKIs now approved in the front-line setting. Alectinib is the preferred first-line option based on its efficacy and side-effect profile. The central nervous system (CNS) activity of alectinib and brigatinib has allowed for treatment of CNS metastases with TKI therapy. Once resistance inevitably develops, newer therapies such as lorlatinib can be considered.


Subject(s)
Anaplastic Lymphoma Kinase , Carbazoles/pharmacology , Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Piperidines/pharmacology , Anaplastic Lymphoma Kinase/antagonists & inhibitors , Anaplastic Lymphoma Kinase/genetics , Antineoplastic Agents/pharmacology , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/pathology , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Mutation , Pharmacogenomic Testing , Protein Kinase Inhibitors/pharmacology
16.
Schizophr Res ; 176(1): 52-71, 2016 09.
Article in English | MEDLINE | ID: mdl-26589391

ABSTRACT

Oxidative stress is a well-recognized participant in the pathophysiology of multiple brain disorders, particularly neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. While not a dementia, a wide body of evidence has also been accumulating for aberrant reactive oxygen species and inflammation in schizophrenia. Here we highlight roles for oxidative stress as a common mechanism by which varied genetic and epidemiologic risk factors impact upon neurodevelopmental processes that underlie the schizophrenia syndrome. While there is longstanding evidence that schizophrenia may not have a single causative lesion, a common pathway involving oxidative stress opens the possibility for intervention at susceptible phases.


Subject(s)
Inflammation , Oxidative Stress , Psychotic Disorders , Reactive Oxygen Species , Schizophrenia , Humans , Inflammation/immunology , Inflammation/metabolism , Psychotic Disorders/immunology , Psychotic Disorders/metabolism , Schizophrenia/immunology , Schizophrenia/metabolism
17.
Neuron ; 78(4): 623-30, 2013 May 22.
Article in English | MEDLINE | ID: mdl-23719162

ABSTRACT

Cocaine's behavioral-stimulant effects derive from potentiation of synaptic signaling by dopamine and serotonin leading to transcriptional alterations in postsynaptic cells. We report that a signaling cascade involving nitric oxide (NO) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mediates cocaine's transcriptional and behavioral actions. Lower, behavioral-stimulant doses enhance the cAMP response element-binding (CREB) signaling system, while higher, neurotoxic doses stimulate the p53 cytotoxic system. The drug CGP3466B, which potently and selectively blocks GAPDH nitrosylation and GAPDH-Siah binding, prevents these actions as well as behavioral effects of cocaine providing a strategy for anticocaine therapy.


Subject(s)
Behavior, Animal/drug effects , Central Nervous System Stimulants/pharmacology , Cocaine/pharmacology , Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)/metabolism , Nitric Oxide/metabolism , Signal Transduction/physiology , Animals , Dose-Response Relationship, Drug , Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating)/drug effects , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Nitric Oxide Synthase Type I/drug effects , Nitric Oxide Synthase Type I/metabolism , Signal Transduction/drug effects , Transcription, Genetic/drug effects
18.
Biochem Biophys Res Commun ; 409(4): 596-602, 2011 Jun 17.
Article in English | MEDLINE | ID: mdl-21539809

ABSTRACT

Glutamate, the principal excitatory neurotransmitter of the brain, participates in a multitude of physiologic and pathologic processes, including learning and memory. Glutathione, a tripeptide composed of the amino acids glutamate, cysteine, and glycine, serves important cofactor roles in antioxidant defense and drug detoxification, but glutathione deficits occur in multiple neuropsychiatric disorders. Glutathione synthesis and metabolism are governed by a cycle of enzymes, the γ-glutamyl cycle, which can achieve intracellular glutathione concentrations of 1-10mM. Because of the considerable quantity of brain glutathione and its rapid turnover, we hypothesized that glutathione may serve as a reservoir of neural glutamate. We quantified glutamate in HT22 hippocampal neurons, PC12 cells and primary cortical neurons after treatment with molecular inhibitors targeting three different enzymes of the glutathione metabolic cycle. Inhibiting 5-oxoprolinase and γ-glutamyl transferase, enzymes that liberate glutamate from glutathione, leads to decreases in glutamate. In contrast, inhibition of γ-glutamyl cysteine ligase, which uses glutamate to synthesize glutathione, results in substantial glutamate accumulation. Increased glutamate levels following inhibition of glutathione synthesis temporally precede later effects upon oxidative stress.


Subject(s)
Glutamic Acid/biosynthesis , Glutathione/metabolism , Neurons/metabolism , Animals , Buthionine Sulfoximine/pharmacology , Cell Line, Tumor , Enzyme Inhibitors/pharmacology , Hippocampus/cytology , Imidazolines/pharmacology , Isoxazoles/pharmacology , Mice , Pyroglutamate Hydrolase/antagonists & inhibitors , Pyroglutamate Hydrolase/metabolism , Rats , gamma-Glutamyltransferase/antagonists & inhibitors , gamma-Glutamyltransferase/metabolism
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