NMDA Receptor and Its Emerging Role in Cancer

Advances in Chiral Metabolomic Profiling and Biomarker Discovery

Chiral metabolomics entails the enantioselective measurement of the metabolome present in a biological system. Over recent years, it has garnered significant interest for its potential in discovering disease biomarkers and aiding clinical diagnostics. D-Amino acids and D-hydroxy acids, traditionally overlooked as unnatural, are now emerging as novel signaling molecules and potential biomarkers for a range of metabolic disorders, brain diseases, kidney disease, diabetes, and cancer. Despite their significance, simultaneous measurements of multiple classes of chiral metabolites in a biological system remain challenging. Hence, limited information is available regarding the metabolic pathways responsible for synthesizing D-amino/hydroxy acid and their associated pathophysiological mechanisms in various diseases. Capitalizing on recent advancements in sensitive analytical techniques, researchers have developed various targeted chiral metabolomic methods for the analysis of chiral biomarkers. Here, we highlight the pivotal role of chiral metabolic profiling studies in disease diagnosis, prognosis, and therapeutic interventions. Furthermore, we describe cutting-edge chromatographic and mass spectrometry methods that enable enantioselective analysis of chiral metabolites. These advanced techniques are instrumental in unraveling the complexities of disease biomarkers, contributing to the ongoing efforts in disease biomarker discovery.

Autocrine glutamate signaling drives cell competition in Drosophila

Cell competition is an evolutionarily conserved quality control process that eliminates suboptimal or potentially dangerous cells. Although differential metabolic states act as direct drivers of competition, how these are measured across tissues is not understood. Here, we demonstrate that vesicular glutamate transporter (VGlut) and autocrine glutamate signaling are required for cell competition and Myc-driven super-competition in the Drosophila epithelia. We find that the loss of glutamate-stimulated VGlut>NMDAR>CaMKII>CrebB signaling triggers loser status and cell death under competitive settings via the autocrine induction of TNF. This in turn drives TNFR>JNK activation, triggering loser cell elimination and PDK/LDH-dependent metabolic reprogramming. Inhibiting caspases or preventing loser cells from transferring lactate to their neighbors nullifies cell competition. Further, in a Drosophila model for premalignancy, Myc-overexpressing clones co-opt this signaling circuit to acquire super-competitor status. Targeting glutamate signaling converts Myc "super-competitor" clones into "losers," highlighting new therapeutic opportunities to restrict the evolution of fitter clones.

Glial alterations in the glutamatergic and GABAergic signaling pathways in a mouse model of Lafora disease, a severe form of progressive myoclonus epilepsy

Lafora disease (LD; OMIM#254780) is a rare form of progressive myoclonus epilepsy characterized by the accumulation of insoluble deposits of aberrant glycogen (polyglucosans), named Lafora bodies (LBs), in the brain but also in peripheral tissues. It is assumed that the accumulation of LBs is related to the appearance of the characteristic pathological features of the disease. In mouse models of LD, we and others have reported an increase in the levels of reactive astrocytes and activated microglia, which triggers the expression of the different pro-inflammatory mediators. Recently, we have demonstrated that the TNF and IL-6 inflammatory signaling pathways are the main mediators of the neuroinflammatory phenotype associated with the disease. In this work, we present evidence that the activation of these pathways produces a dysregulation in the levels of different subunits of the excitatory ionotropic glutamatergic receptors (phopho-GluN2B, phospho-GluA2, GluK2) and also an increase in the levels of the GABA transporter GAT1 in the hippocampus of the Epm2b-/- mice. In addition, we present evidence of the presence of activated forms of the Src and Lyn protein kinases in this area. These effects may increase the excitatory glutamatergic signaling and decrease the inhibitory GABAergic tone, leading to hyper-excitability. More importantly, the enhanced production of these subunits occurs in non-neuronal cells such as activated microglia and reactive astrocytes, pointing out a key role of glia in the pathophysiology of LD.

Occult Lung Cancer-Associated Autoimmune Encephalitis Presenting as Acute Psychosis

During deployment, a 52-year-old male developed acute behavioral changes. Though initially considered to have PTSD and related agitation and confusional state, his evaluation was consistent with acute encephalopathy. Magnetic resonance imaging of the brain showed T2 hyperintensities, and CSF analysis was positive for anti-N-methyl-D-aspartate receptor antibody. A nuclear protein in testis carcinoma midline carcinoma was discovered in the lung. Immunotherapy and surgical resection led to steady improvement prior to adjuvant chemotherapy. Autoimmune encephalitis due to anti-N-methyl-D-aspartate receptor antibodies is increasingly being recognized as causal of acute behavioral change.

m6A-YTHDF1 Mediated Regulation of GRIN2D in Bladder Cancer Progression and Aerobic Glycolysis

The modification of N6-methyladenosine (m6A), primarily orchestrated by the reader protein YTHDF1, is a pivotal element in the post-transcriptional regulation of genes. While its role in various biological processes is well-documented, the specific impact of m6A-YTHDF1 on the regulation of GRIN2D, a gene implicated in cancer biology, particularly in the context of bladder cancer, is not thoroughly understood. Utilizing a series of bioinformatics analyses and experimental approaches, including cell culture, transfection, RT-qPCR, and western blotting, we investigated the m6A modification landscape in bladder cancer cells. The relationship between m6A-YTHDF1 and GRIN2D expression was examined, followed by functional assays to assess their roles in cancer progression and glycolytic activity. Our analysis identified a significant upregulation of m6A modification in bladder cancer tissues. YTHDF1 was found to regulate GRIN2D expression positively. Functionally, GRIN2D was implicated in promoting bladder cancer cell proliferation and enhancing aerobic glycolysis. Inhibition of the m6A-YTHDF1-GRIN2D axis resulted in the suppression of cancer progression and metabolic alterations. Through this research, we have elucidated the significant influence of the m6A-YTHDF1 axis on the modulation of GRIN2D expression, which in turn markedly impacts the progression of bladder cancer and its metabolic pathways, particularly aerobic glycolysis. Our findings uncover critical molecular dynamics within bladder cancer cells, offering a deeper understanding of its pathophysiology. Furthermore, the insights gained from this study underscore the potential of targeting the m6A-YTHDF1-GRIN2D pathway for the development of innovative therapeutic strategies in the treatment of bladder cancer.

NMDA receptor-mediated Ca2+ signaling: Impact on cell cycle regulation and the development of neurodegenerative diseases and cancer

NMDA receptors are Ca2+-permeable ligand-gated ion channels that mediate fast excitatory transmission in the central nervous system. NMDA receptors regulate the proliferation and differentiation of neural progenitor cells and also play critical roles in neural plasticity, memory, and learning. In addition to their physiological role, NMDA receptors are also involved in glutamate-mediated excitotoxicity, which results from excessive glutamate stimulation, leading to Ca2+ overload, and ultimately to neuronal death. Thus, NMDA receptor-mediated excitotoxicity has been linked to several neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, dementia, and stroke. Interestingly, in addition to its effects on cell death, aberrant expression or activation of NMDA receptors is also involved in pathological cellular proliferation, and is implicated in the invasion and proliferation of various types of cancer. These disorders are thought to be related to the contribution of NMDA receptors to cell proliferation and cell death through cell cycle modulation. This review aims to discuss the evidence implicating NMDA receptor activity in cell cycle regulation and the link between aberrant NMDA receptor activity and the development of neurodegenerative diseases and cancer due to cell cycle dysregulation. The information presented here will provide insights into the signaling pathways and the contribution of NMDA receptors to these diseases, and suggests that NMDA receptors are promising targets for the prevention and treatment of these diseases, which are leading causes of death and disability worldwide.

Perioperative Ketamine and Cancer Recurrence: A Comprehensive Review

Cancer is a significant global health threat and a leading cause of death worldwide. Effective early-stage interventions, particularly surgery, can potentially cure many solid tumors. However, the risk of postoperative cancer recurrence remains high. Recent research highlights the influence of perioperative anesthetic and analgesic choices on the fate of residual cancer cells, potentially affecting recurrence risks. Among these agents, ketamine-a well-known anesthetic and analgesic-has garnered interest due to its antitumor properties, mainly through inhibiting the N-methyl-D-aspartate (NMDA) receptor found in various cancer tissues. Additionally, ketamine's potential immunomodulatory effects, given the expression of NMDA receptors on immune cells, suggest that it plays a significant role during the perioperative period. This review synthesizes current evidence on ketamine's impact on cancer cell biology, inflammation, immune modulation, and the role of the gut microbiota, proposing ketamine as a promising agent for enhancing oncological outcomes.

DNA Methylation Signatures Correlate with Response to Immune Checkpoint Inhibitors in Metastatic Melanoma

BACKGROUND

DNA methylation profiles have emerged as potential predictors of therapeutic response in various solid tumors.

OBJECTIVE

This study aimed to analyze the DNA methylation profiles of patients with stage IV metastatic melanoma undergoing first-line immune checkpoint inhibitor treatment and evaluate their correlation with a radiological response according to immune-related Response Evaluation Criteria in Solid Tumors (iRECIST).

METHODS

A total of 81 tissue samples from 71 patients with metastatic melanoma (27 female, 44 male) were included in this study. We utilized Illumina Methylation EPIC Beadchips to retrieve their genome-wide methylation profile by interrogating >850,000 CpG sites. Clustering based on the 500 most differentially methylated genes was conducted to identify distinct methylation patterns associated with immune checkpoint inhibitor response. Results were further aligned with an independent, previously published data set.

RESULTS

The median progression-free survival was 8.5 months (range: 0-104.1 months), and the median overall survival was 30.6 months (range: 0-104.1 months). Objective responses were observed in 29 patients (40.8%). DNA methylation profiling revealed specific signatures that correlated with radiological response to immune checkpoint inhibitors. Three distinct clusters were identified based on the methylation patterns of the 500 most differentially methylated genes. Cluster 1 (12/12) and cluster 2 (12/24) exhibited a higher proportion of responders, while cluster 3 (39/45) predominantly consisted of non-responders. In the validation data set, responders also showed more frequent hypomethylation although differences in the data sets limit the interpretation.

CONCLUSIONS

These findings suggest that DNA methylation profiling of tumor tissues might serve as a predictive biomarker for immune checkpoint inhibitor response in patients with metastatic melanoma. Further validation studies are warranted to confirm the efficiency of DNA methylation profiling as a predictive tool in the context of immunotherapy for metastatic melanoma.

MET Oncogene Enhances Pro-Migratory Functions by Counteracting NMDAR2B Cleavage

The involvement of the N-methyl-D-aspartate receptor (NMDAR), a glutamate-gated ion channel, in promoting the invasive growth of cancer cells is an area of ongoing investigation. Our previous findings revealed a physical interaction between NMDAR and MET, the hepatocyte growth factor (HGF) receptor. However, the molecular mechanisms underlying this NMDAR/MET interaction remain unclear. In this study, we demonstrate that the NMDAR2B subunit undergoes proteolytic processing, resulting in a low-molecular-weight form of 100 kDa. Interestingly, when the NMDAR2B and MET constructs were co-transfected, the full-size high-molecular-weight NMDAR2B form of 160 kDa was predominantly observed. The protection of NMDAR2B from cleavage was dependent on the kinase activity of MET. We provide the following evidence that MET opposes the autophagic lysosomal proteolysis of NMDAR2B: (i) MET decreased the protein levels of lysosomal cathepsins; (ii) treatment with either an inhibitor of autophagosome formation or the fusion of the autophagosome and lysosome elevated the proportion of the NMDAR2B protein's uncleaved form; (iii) a specific mTOR inhibitor hindered the anti-autophagic effect of MET. Finally, we demonstrate that MET coopts NMDAR2B to augment cell migration. This implies that MET harnesses the functionality of NMDAR2B to enhance the ability of cancer cells to migrate.

Ligand-Gated Ion Channels: Prognostic and Therapeutic Implications for Gliomas

Gliomas are common primary brain malignancies that remain difficult to treat due to their overall aggressiveness and heterogeneity. Although a variety of therapeutic strategies have been employed for the treatment of gliomas, there is increasing evidence that suggests ligand-gated ion channels (LGICs) can serve as a valuable biomarker and diagnostic tool in the pathogenesis of gliomas. Various LGICs, including P2X, SYT16, and PANX2, have the potential to become altered in the pathogenesis of glioma, which can disrupt the homeostatic activity of neurons, microglia, and astrocytes, further exacerbating the symptoms and progression of glioma. Consequently, LGICs, including purinoceptors, glutamate-gated receptors, and Cys-loop receptors, have been targeted in clinical trials for their potential therapeutic benefit in the diagnosis and treatment of gliomas. In this review, we discuss the role of LGICs in the pathogenesis of glioma, including genetic factors and the effect of altered LGIC activity on the biological functioning of neuronal cells. Additionally, we discuss current and emerging investigations regarding the use of LGICs as a clinical target and potential therapeutic for gliomas.

Calcium Homeostasis, Transporters, and Blockers in Health and Diseases of the Cardiovascular System

Calcium is a highly positively charged ionic species. It regulates all cell types' functions and is an important second messenger that controls and triggers several mechanisms, including membrane stabilization, permeability, contraction, secretion, mitosis, intercellular communications, and in the activation of kinases and gene expression. Therefore, controlling calcium transport and its intracellular homeostasis in physiology leads to the healthy functioning of the biological system. However, abnormal extracellular and intracellular calcium homeostasis leads to cardiovascular, skeletal, immune, secretory diseases, and cancer. Therefore, the pharmacological control of calcium influx directly via calcium channels and exchangers and its outflow via calcium pumps and uptake by the ER/SR are crucial in treating calcium transport remodeling in pathology. Here, we mainly focused on selective calcium transporters and blockers in the cardiovascular system.