A glial blueprint for gliomagenesis

Lipid metabolic rewiring in glioma‑associated microglia/macrophages (Review)

Gliomas are the most prevailing brain malignancy in both children and adults. Microglia, which are resident in the central nervous system (CNS), are distributed throughout the brain and serve an important role in the immunity of the CNS. Microglial cells exhibit varying phenotypic and metabolic properties during different stages of glioma development, making them a highly dynamic cell population. In particular, glioma‑associated microglia/macrophages (GAMs) can alter their metabolic characteristics and influence malignancies in response to the signals they receive. The significance of macrophage metabolic reprogramming in tumor growth is becoming increasingly acknowledged in recent years. However, to the best of our knowledge, there is currently a scarcity of data from investigations into the lipid metabolic profiles of microglia/macrophages in the glioma setting. Therefore, the present review aims to provide a thorough review of the role that lipid metabolism serves in tumor‑associated macrophages. In addition, it outlines potential targets for therapy based on lipid metabolism. The present review aims to serve as a reference source for future investigations into GAMs.

Single-cell and spatial transcriptome assays reveal heterogeneity in gliomas through stress responses and pathway alterations

Background

Glioma is a highly heterogeneous malignancy of the central nervous system. This heterogeneity is driven by various molecular processes, including neoplastic transformation, cell cycle dysregulation, and angiogenesis. Among these biomolecular events, inflammation and stress pathways in the development and driving factors of glioma heterogeneity have been reported. However, the mechanisms of glioma heterogeneity under stress response remain unclear, especially from a spatial aspect.

Methods

This study employed single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) to explore the impact of oxidative stress response genes in oligodendrocyte precursor cells (OPCs). Our analysis identified distinct pathways activated by oxidative stress in two different types of gliomas: high- and low- grade (HG and LG) gliomas.

Results

In HG gliomas, oxidative stress induced a metabolic shift from oxidative phosphorylation to glycolysis, promoting cell survival by preventing apoptosis. This metabolic reprogramming was accompanied by epithelial-to-mesenchymal transition (EMT) and an upregulation of stress response genes. Furthermore, SCENIC (Single-Cell rEgulatory Network Inference and Clustering) analysis revealed that oxidative stress activated the AP1 transcription factor in HG gliomas, thereby enhancing tumor cell survival and proliferation.

Conclusion

Our findings provide a novel perspective on the mechanisms of oxidative stress responses across various grades of gliomas. This insight enhances our comprehension of the evolutionary processes and heterogeneity within gliomas, potentially guiding future research and therapeutic strategies.

PTBP1-mediated repression of neuron-specific CDC42 splicing constitutes a genomic alteration-independent, developmentally conserved vulnerability in IDH-wildtype glioblastoma

Gene co-expression networks may encode hitherto inadequately recognized vulnerabilities for adult gliomas. By identifying evolutionally conserved gene co-expression modules around EGFR (EM) or PDGFRA (PM), we recently proposed an EM/PM classification scheme, which assigns IDH-wildtype glioblastomas (GBM) into the EM subtype committed in neural stem cell compartment, IDH-mutant astrocytomas and oligodendrogliomas into the PM subtype committed in early oligodendrocyte lineage. Here, we report the identification of EM/PM subtype-specific gene co-expression networks and the characterization of hub gene polypyrimidine tract-binding protein 1 (PTBP1) as a genomic alteration-independent vulnerability in IDH-wildtype GBM. Supervised by the EM/PM classification scheme, we applied weighted gene co-expression network analysis to identify subtype-specific global gene co-expression modules. These gene co-expression modules were characterized for their clinical relevance, cellular origin and conserved expression pattern during brain development. Using lentiviral vector-mediated constitutive or inducible knockdown, we characterized the effects of PTBP1 on the survival of IDH-wildtype GBM cells, which was complemented with the analysis of PTBP1-depedent splicing pattern and overexpression of splicing target neuron-specific CDC42 (CDC42-N) isoform.  Transcriptomes of adult gliomas can be robustly assigned into 4 large gene co-expression modules that are prognostically relevant and are derived from either malignant cells of the EM/PM subtypes or tumor microenvironment. The EM subtype is associated with a malignant cell-intrinsic gene module involved in pre-mRNA splicing, DNA replication and damage response, and chromosome segregation, and a microenvironment-derived gene module predominantly involved in extracellular matrix organization and infiltrating immune cells. The PM subtype is associated with two malignant cell-intrinsic gene modules predominantly involved in transcriptional regulation and mRNA translation, respectively. Expression levels of these gene modules are independent prognostic factors and malignant cell-intrinsic gene modules are conserved during brain development. Focusing on the EM subtype, we identified PTBP1 as the most significant hub for the malignant cell-intrinsic gene module. PTBP1 is not altered in most glioma genomes. PTBP1 represses the conserved splicing of CDC42-N. PTBP1 knockdown or CDC42-N overexpression disrupts actin cytoskeleton dynamics, causing accumulation of reactive oxygen species and cell apoptosis. PTBP1-mediated repression of CDC42-N splicing represents a potential genomic alteration-independent, developmentally conserved vulnerability in IDH-wildtype GBM.

TCAF2 drives glioma cellular migratory/invasion properties through STAT3 signaling

Glioma is an intracranial tumor characterized by high mortality and recurrence rates. In the present study, the association of TRPM8 channel-associated factor 2 (TCAF2) in glioma was investigated using bioinformatics, showing significant relationships with age, WHO grade, IDH, and 1p/19q status, as well as being an independent predictor of prognosis. Immunohistochemistry of a glioma sample microarray showed markedly increased TCAF2 expression in glioblastoma relative to lower-grade glioma, with elevated expression predominating in the tumor center. Raised TCAF2 levels promote glioma cell migratory/invasion properties through the epithelial-to-mesenchymal transition-like (EMT-like) process, shown by Transwell and scratch assays and western blotting. It was further found that the effects of TCAF2 were mediated by the activation of STAT3. These results suggest that TCAF2 promotes glioma cell migration and invasion, rendering it a potential drug target in glioma therapy.

PRAMEF12, a novel cancer/testis gene, regulates proliferation and apoptosis to promote progression of glioma

Aim: To evaluate whether PRAMEF12 can serve as a diagnostic biomarker for glioma. Methods: We examined PRAMEF12 expression in multiple normal and glioma tissues. The diagnostic value of PRAMEF12 was evaluated using receiver operating characteristic curve analysis. The effect of PRAMEF12 ablation on proliferation, cell cycle and apoptosis was investigated. Database analyses were utilized for functional enrichment analysis. Results: PRAMEF12 expression in normal tissue was restricted to the human testis. PRAMEF12 displayed significant diagnostic value in glioma. PRAMEF12 knockdown inhibited cell proliferation, induced apoptosis and resulted in induction of S-phase cell cycle arrest. Pathway enrichment analysis indicated that PRAMEF12 may participate in cancer. Conclusion: PRAMEF12, a novel cancer/testis gene, may be a potential new diagnostic biomarker for glioma.

Enhancing Surface Hydroxyl Group Modulation on Carbon Nitride Boosts the Effectiveness of Photodynamic Treatment for Brain Glioma

The effectiveness of photodynamic therapy (PDT) in treating brain gliomas is limited by the solubility of photosensitizers and the production of reactive oxygen species (ROS), both of which are influenced by the concentration of photosensitizers and catalyst active sites. In this study, we developed a controllable surface hydroxyl concentration for the photosensitizer CN11 to address its poor water solubility issue and enhance PDT efficacy in tumor treatment. Compared to pure g-C3N4 (CN), CN11 exhibited 4.6 times higher hydrogen peroxide production under visible light, increased incidence of the n → π* electron transition, and provided more available reaction sites for cytotoxic ROS generation. These findings resulted in a 2.43-fold increase in photodynamic treatment efficacy against brain glioma cells. Furthermore, in vivo experiments conducted on mice demonstrated that CN11 could be excreted through normal cell metabolism with low cytotoxicity and high biosafety, effectively achieving complete eradication of tumor cells.

Two Mixed-Ligand Co(II) Complexes as Luminescent Materials and Loaded with Temozolomide-gel Particles in Nursing Against Glioma

By employing a mixed-ligand strategy, we synthesized two new coordination polymers (CPs) featuring Co(II): {Co(H2L)(bib)]·2H2O}n (1) and {Co(L)(bib)2]·2H2O}n (2), where H4L represents 5-(3,5-dicarboxybenzyloxy) isophthalic acid, and bib denotes 1,4-bis(1-imidazolyl)benzene. These CPs were obtained through the reaction of H4L, a flexible carboxylic acid ligand, with Co(NO3)2·6H2O in various solvent mixtures, along with the N-donor co-ligand bib. Complexes 1 and 2 are formed through distinct coordination modes, resulting in their distinct structural features and excellent fluorescent properties. Based on ligand-centered fluorescence emission and the blue shift (CP 1) along with red shift (CP 2) characteristics, both complexes show promise for applications in fields such as blue fluorescence sensing materials and luminescent materials. After successfully synthesizing two CPs, CP 1 was chosen as the carrier for loading temozolomide (TMZ). Subsequently, leveraging the unique advantages of hydrogels, we developed a novel metal gel formulation loaded with TMZ. The inhibitory effect of this formulation on the growth of glioblastoma was evaluated. Our results demonstrate a significant suppression of glioblastoma cell proliferation by this system, providing an effective avenue for glioblastoma treatment.

Endoplasmic Reticulum Stress in Gliomas: Exploiting a Dual-Effect Dysfunction through Chemical Pharmaceutical Compounds and Natural Derivatives for Therapeutical Uses

The endoplasmic reticulum maintains proteostasis, which can be disrupted by oxidative stress, nutrient deprivation, hypoxia, lack of ATP, and toxicity caused by xenobiotic compounds, all of which can result in the accumulation of misfolded proteins. These stressors activate the unfolded protein response (UPR), which aims to restore proteostasis and avoid cell death. However, endoplasmic response-associated degradation (ERAD) is sometimes triggered to degrade the misfolded and unassembled proteins instead. If stress persists, cells activate three sensors: PERK, IRE-1, and ATF6. Glioma cells can use these sensors to remain unresponsive to chemotherapeutic treatments. In such cases, the activation of ATF4 via PERK and some proteins via IRE-1 can promote several types of cell death. The search for new antitumor compounds that can successfully and directly induce an endoplasmic reticulum stress response ranges from ligands to oxygen-dependent metabolic pathways in the cell capable of activating cell death pathways. Herein, we discuss the importance of the ER stress mechanism in glioma and likely therapeutic targets within the UPR pathway, as well as chemicals, pharmaceutical compounds, and natural derivatives of potential use against gliomas.

Tumour Size and Overall Survival in a Cohort of Patients with Unifocal Glioblastoma: A Uni- and Multivariable Prognostic Modelling and Resampling Study

Published models inconsistently associate glioblastoma size with overall survival (OS). This study aimed to investigate the prognostic effect of tumour size in a large cohort of patients diagnosed with GBM and interrogate how sample size and non-linear transformations may impact on the likelihood of finding a prognostic effect. In total, 279 patients with a IDH-wildtype unifocal WHO grade 4 GBM between 2014 and 2020 from a retrospective cohort were included. Uni-/multivariable association between core volume, whole volume (CV and WV), and diameter with OS was assessed with (1) Cox proportional hazard models +/- log transformation and (2) resampling with 1,000,000 repetitions and varying sample size to identify the percentage of models, which showed a significant effect of tumour size. Models adjusted for operation type and a diameter model adjusted for all clinical variables remained significant (p = 0.03). Multivariable resampling increased the significant effects (p < 0.05) of all size variables as sample size increased. Log transformation also had a large effect on the chances of a prognostic effect of WV. For models adjusted for operation type, 19.5% of WV vs. 26.3% log-WV (n = 50) and 69.9% WV and 89.9% log-WV (n = 279) were significant. In this large well-curated cohort, multivariable modelling and resampling suggest tumour volume is prognostic at larger sample sizes and with log transformation for WV.

A network pharmacology- and transcriptomics-based investigation reveals an inhibitory role of β-sitosterol in glioma via the EGFR/MAPK signaling pathway

Glioma is characterized by rapid cell proliferation, aggressive invasion, altered apoptosis and a poor prognosis. β-Sitosterol, a kind of phytosterol, has been shown to possess anticancer activities. Our current study aims to investigate the effects of β-sitosterol on gliomas and reveal the underlying mechanisms. Our results show that β-sitosterol effectively inhibits the growth of U87 cells by inhibiting proliferation and inducing G2/M phase arrest and apoptosis. In addition, β-sitosterol inhibits migration by downregulating markers of epithelial-mesenchymal transition (EMT). Mechanistically, network pharmacology and transcriptomics approaches illustrate that the EGFR/MAPK signaling pathway may be responsible for the inhibitory effect of β-sitosterol on glioma. Afterward, the results show that β-sitosterol effectively suppresses the EGFR/MAPK signaling pathway. Moreover, β-sitosterol significantly inhibits tumor growth in a U87 xenograft nude mouse model. β-Sitosterol inhibits U87 cell proliferation and migration and induces apoptosis and cell cycle arrest in U87 cells by blocking the EGFR/MAPK signaling pathway. These results suggest that β-sitosterol may be a promising therapeutic agent for the treatment of glioma.

Effect of gold-conjugated resveratrol nanoparticles on glioma cells and its underlying mechanism

BACKGROUND

 Glioblastoma is the most aggressive brain tumor with poor prognosis. Although Resveratrol (Rsv) is known to have therapeutic effects on glioma, the effects of gold-conjugated resveratrol nanoparticles (Rsv-AuNPs) on glioma cells are rarely reported.

OBJECTIVE

We aimed to investigate the effects of Rsv-AuNPs on glioma cells and its underlying mechanism.

METHOD

Human glioma cell line U87 was treated with different concentrations of Rsv-AuNPs. CCK-8, transwell, and wound healing assay were performed to measure the effects of Rsv-AuNPs on cell proliferation, invasion, and migration ability, respectively. Flow cytometry assay was used to detect the effects of Rsv-AuNPs on apoptosis. Changes of protein expressions related to proliferation, invasion, migration, and apoptosis were measured by Western blot assay. In addition, the inhibitory role of Rsv-AuNPs in the PI3K/AKT/mTOR signaling pathway was verified by using PI3K inhibitor LY294002.

RESULTS

Rsv-AuNPs treatment significantly suppressed proliferation, migration, and invasion of U87 cells (all P < 0.05) and increased the apoptosis rate (P < 0.05). The changes of proteins related to proliferation, migration, invasion and apoptosis were consistent (all P < 0.05). Moreover, Rsv-AuNPs treatment significantly inhibited the phosphorylation of PI3K, AKT and mTOR proteins in U87 cells (P < 0.05).

CONCLUSION

The present study found that Rsv-AuNPs inhibited the proliferation, migration, and invasion of U87 cells and induced apoptosis by inhibiting the activation of PI3K/AKT/mTOR signaling pathway. In the future, Rsv-AuNPs might be applied to the clinical treatment of glioma through more in-depth animal and clinical research.

From signalling to form: the coordination of neural tube patterning

The development of the vertebrate spinal cord involves the formation of the neural tube and the generation of multiple distinct cell types. The process starts during gastrulation, combining axial elongation with specification of neural cells and the formation of the neuroepithelium. Tissue movements produce the neural tube which is then exposed to signals that provide patterning information to neural progenitors. The intracellular response to these signals, via a gene regulatory network, governs the spatial and temporal differentiation of progenitors into specific cell types, facilitating the assembly of functional neuronal circuits. The interplay between the gene regulatory network, cell movement, and tissue mechanics generates the conserved neural tube pattern observed across species. In this review we offer an overview of the molecular and cellular processes governing the formation and patterning of the neural tube, highlighting how the remarkable complexity and precision of vertebrate nervous system arises. We argue that a multidisciplinary and multiscale understanding of the neural tube development, paired with the study of species-specific strategies, will be crucial to tackle the open questions.

Celecoxib Suppresses NF-κB p65 (RelA) and TNFα Expression Signaling in Glioblastoma

BACKGROUND

Glioblastoma (GBM) harbors significant genetic heterogeneity, high infiltrative capacity, and patterns of relapse following many therapies. The expression of nuclear factor kappa-B (NF-κB p65 (RelA)) and signaling pathways is constitutively activated in GBM through inflammatory stimulation such as tumor necrosis factor-alpha (TNFα), cell invasion, motility, abnormal physiological stimuli, and inducible chemoresistance. However, the underlying anti-tumor and anti-proliferative mechanisms of NF-κB p65 (RelA) and TNFα are still poorly defined. This study aimed to investigate the expression profiling of NF-κB p65 (RelA) and TNFα as well as the effectiveness of celecoxib along with temozolomide (TMZ) in reducing the growth of the human GBM cell line SF-767.

METHODS

genome-wide expression profiling, enrichment analysis, immune infiltration, quantitative expression, and the Microculture Tetrazolium Test (MTT) proliferation assay were performed to appraise the effects of celecoxib and TMZ.

RESULTS

demonstrated the upregulation of NF-κB p65 (RelA) and TNFα and celecoxib reduced the viability of the human glioblastoma cell line SF-767, cell proliferation, and NF-κB p65 (RelA) and TNFα expression in a dose-dependent manner. Overall, these findings demonstrate for the first time how celecoxib therapy could mitigate the invasive characteristics of the human GBM cell line SF-767 by inhibiting the NF-κB mediated stimulation of the inflammatory cascade.

CONCLUSION

based on current findings, we propose that celecoxib as a drug candidate in combination with temozolomide might dampen the transcriptional and enzymatic activities associated with the aggressiveness of GBM and reduce the expression of GBM-associated NF-κB p65 (RelA) and TNFα inflammatory genes expression.

Advances in glioma models using in vivo electroporation to highjack neurodevelopmental processes

Glioma is the most prevalent type of neurological malignancies. Despite decades of efforts in neurosurgery, chemotherapy and radiation therapy, glioma remains one of the most treatment-resistant brain tumors with unfavorable outcomes. Recent progresses in genomic and epigenetic profiling have revealed new concepts of genetic events involved in the etiology of gliomas in humans, meanwhile, revolutionary technologies in gene editing and delivery allows to code these genetic "events" in animals to genetically engineer glioma models. This approach models the initiation and progression of gliomas in a natural microenvironment with an intact immune system and facilitates probing therapeutic strategies. In this review, we focus on recent advances in in vivo electroporation-based glioma modeling and outline the established genetically engineered glioma models (GEGMs).

Advanced Temporally-Spatially Precise Technologies for On-Demand Neurological Disorder Intervention

Temporal-spatial precision has attracted increasing attention for the clinical intervention of neurological disorders (NDs) to mitigate adverse effects of traditional treatments and achieve point-of-care medicine. Inspiring steps forward in this field have been witnessed in recent years, giving the credit to multi-discipline efforts from neurobiology, bioengineering, chemical materials, artificial intelligence, and so on, exhibiting valuable clinical translation potential. In this review, the latest progress in advanced temporally-spatially precise clinical intervention is highlighted, including localized parenchyma drug delivery, precise neuromodulation, as well as biological signal detection to trigger closed-loop control. Their clinical potential in both central and peripheral nervous systems is illustrated meticulously related to typical diseases. The challenges relative to biosafety and scaled production as well as their future perspectives are also discussed in detail. Notably, these intelligent temporally-spatially precision intervention systems could lead the frontier in the near future, demonstrating significant clinical value to support billions of patients plagued with NDs.

Assessment and prediction of glioblastoma therapy response: challenges and opportunities

Glioblastoma is the most aggressive type of primary adult brain tumour. The median survival of patients with glioblastoma remains approximately 15 months, and the 5-year survival rate is <10%. Current treatment options are limited, and the standard of care has remained relatively constant since 2011. Over the last decade, a range of different treatment regimens have been investigated with very limited success. Tumour recurrence is almost inevitable with the current treatment strategies, as glioblastoma tumours are highly heterogeneous and invasive. Additionally, another challenging issue facing patients with glioblastoma is how to distinguish between tumour progression and treatment effects, especially when relying on routine diagnostic imaging techniques in the clinic. The specificity of routine imaging for identifying tumour progression early or in a timely manner is poor due to the appearance similarity of post-treatment effects. Here, we concisely describe the current status and challenges in the assessment and early prediction of therapy response and the early detection of tumour progression or recurrence. We also summarize and discuss studies of advanced approaches such as quantitative imaging, liquid biomarker discovery and machine intelligence that hold exceptional potential to aid in the therapy monitoring of this malignancy and early prediction of therapy response, which may decisively transform the conventional detection methods in the era of precision medicine.

Stalled oligodendrocyte differentiation in IDH-mutant gliomas

BACKGROUND

Roughly 50% of adult gliomas harbor isocitrate dehydrogenase (IDH) mutations. According to the 2021 WHO classification guideline, these gliomas are diagnosed as astrocytomas, harboring no 1p19q co-deletion, or oligodendrogliomas, harboring 1p19q co-deletion. Recent studies report that IDH-mutant gliomas share a common developmental hierarchy. However, the neural lineages and differentiation stages in IDH-mutant gliomas remain inadequately characterized.

METHODS

Using bulk transcriptomes and single-cell transcriptomes, we identified genes enriched in IDH-mutant gliomas with or without 1p19q co-deletion, we also assessed the expression pattern of stage-specific signatures and key regulators of oligodendrocyte lineage differentiation. We compared the expression of oligodendrocyte lineage stage-specific markers between quiescent and proliferating malignant single cells. The gene expression profiles were validated using RNAscope analysis and myelin staining and were further substantiated using data of DNA methylation and single-cell ATAC-seq. As a control, we assessed the expression pattern of astrocyte lineage markers.

RESULTS

Genes concordantly enriched in both subtypes of IDH-mutant gliomas are upregulated in oligodendrocyte progenitor cells (OPC). Signatures of early stages of oligodendrocyte lineage and key regulators of OPC specification and maintenance are enriched in all IDH-mutant gliomas. In contrast, signature of myelin-forming oligodendrocytes, myelination regulators, and myelin components are significantly down-regulated or absent in IDH-mutant gliomas. Further, single-cell transcriptomes of IDH-mutant gliomas are similar to OPC and differentiation-committed oligodendrocyte progenitors, but not to myelinating oligodendrocyte. Most IDH-mutant glioma cells are quiescent; quiescent cells and proliferating cells resemble the same differentiation stage of oligodendrocyte lineage. Mirroring the gene expression profiles along the oligodendrocyte lineage, analyses of DNA methylation and single-cell ATAC-seq data demonstrate that genes of myelination regulators and myelin components are hypermethylated and show inaccessible chromatin status, whereas regulators of OPC specification and maintenance are hypomethylated and show open chromatin status. Markers of astrocyte precursors are not enriched in IDH-mutant gliomas.

CONCLUSIONS

Our studies show that despite differences in clinical manifestation and genomic alterations, all IDH-mutant gliomas resemble early stages of oligodendrocyte lineage and are stalled in oligodendrocyte differentiation due to blocked myelination program. These findings provide a framework to accommodate biological features and therapy development for IDH-mutant gliomas.

Kynureninase Promotes Immunosuppression and Predicts Survival in Glioma Patients: In Silico Data Analyses of the Chinese Glioma Genome Atlas (CGGA) and of the Cancer Genome Atlas (TCGA)

Kynureninase (KYNU) is a kynurenine pathway (KP) enzyme that produces metabolites with immunomodulatory properties. In recent years, overactivation of KP has been associated with poor prognosis of several types of cancer, in particular by promoting the invasion, metastasis, and chemoresistance of cancer cells. However, the role of KYNU in gliomas remains to be explored. In this study, we used the available data from TCGA, CGGA and GTEx projects to analyze KYNU expression in gliomas and healthy tissue, as well as the potential contribution of KYNU in the tumor immune infiltrate. In addition, immune-related genes were screened with KYNU expression. KYNU expression correlated with the increased malignancy of astrocytic tumors. Survival analysis in primary astrocytomas showed that KYNU expression correlated with poor prognosis. Additionally, KYNU expression correlated positively with several genes related to an immunosuppressive microenvironment and with the characteristic immune tumor infiltrate. These findings indicate that KYNU could be a potential therapeutic target for modulating the tumor microenvironment and enhancing an effective antitumor immune response.

Glioblastoma Multiforme: Probing Solutions to Systemic Toxicity towards High-Dose Chemotherapy and Inflammatory Influence in Resistance against Temozolomide

Temozolomide (TMZ), the first-line chemotherapeutic drug against glioblastoma multiforme (GBM), often fails to provide the desired clinical outcomes due to inflammation-induced resistance amid inefficient drug delivery across the blood-brain barrier (BBB). The current study utilized solid lipid nanoparticles (SLNPs) for targeted delivery of TMZ against GBM. After successful formulation and characterization of SLNPs and conjugation with TMZ (SLNP-TMZ), their in-vitro anti-cancer efficacy and effect on the migratory potential of cancer cells were evaluated using temozolomide-sensitive (U87-S) as well as TMZ-resistant (U87-R) glioma cell lines. Elevated cytotoxicity and reduction in cell migration in both cell lines were observed with SLNP-TMZ as compared to the free drug (p < 0.05). Similar results were obtained in-vivo using an orthotopic xenograft mouse model (XM-S and XM-R), where a reduction in tumor size was observed with SLNP-TMZ treatment compared to TMZ. Concomitantly, higher concentrations of the drug were found in brain tissue resections of mice treated with SLNP-TMZ as compared to other vital organs than mice treated with free TMZ. Expression of inflammatory markers (Interleukin-1β, Interleukin-6 and Tumor Necrosis factor-α) in a resistant cell line (U87-R) and its respective mouse model (XM-R) were also found to be significantly elevated as compared to the sensitive U87-S cell line and its respective mouse model (XM-S). Thus, the in-vitro and in-vivo results of the study strongly support the potential application of SLNP-TMZ for TMZ-sensitive and resistant GBM therapy, indicatively through inflammatory mechanisms, and thus merit further detailed insights.

Understanding the Epitranscriptome for Avant-Garde Brain Tumour Diagnostics

RNA modifications are diverse, dynamic, and reversible transcript alterations rapidly gaining attention due to their newly defined RNA regulatory roles in cellular pathways and pathogenic mechanisms. The exciting emerging field of 'epitranscriptomics' is predominantly centred on studying the most abundant mRNA modification, N6-methyladenine (m⁶A). The m⁶A mark, similar to many other RNA modifications, is strictly regulated by so-called 'writer', 'reader', and 'eraser' protein species. The abundance of genes coding for the expression of these regulator proteins and m⁶A levels shows great potential as diagnostic and predictive tools across several cancer fields. This review explores our current understanding of RNA modifications in glioma biology and the potential of epitranscriptomics to develop new diagnostic and predictive classification tools that can stratify these highly complex and heterogeneous brain tumours.

Temporal and spatial stability of the EM/PM molecular subtypes in adult diffuse glioma

Detailed characterizations of genomic alterations have not identified subtype-specific vulnerabilities in adult gliomas. Mapping gliomas into developmental programs may uncover new vulnerabilities that are not strictly related to genomic alterations. After identifying conserved gene modules co-expressed with EGFR or PDGFRA (EM or PM), we recently proposed an EM/PM classification scheme for adult gliomas in a histological subtype- and grade-independent manner. By using cohorts of bulk samples, paired primary and recurrent samples, multi-region samples from the same glioma, single-cell RNA-seq samples, and clinical samples, we here demonstrate the temporal and spatial stability of the EM and PM subtypes. The EM and PM subtypes, which progress in a subtype-specific mode, are robustly maintained in paired longitudinal samples. Elevated activities of cell proliferation, genomic instability and microenvironment, rather than subtype switching, mark recurrent gliomas. Within individual gliomas, the EM/PM subtype was preserved across regions and single cells. Malignant cells in the EM and PM gliomas were correlated to neural stem cell and oligodendrocyte progenitor cell compartment, respectively. Thus, while genetic makeup may change during progression and/or within different tumor areas, adult gliomas evolve within a neurodevelopmental framework of the EM and PM molecular subtypes. The dysregulated developmental pathways embedded in these molecular subtypes may contain subtype-specific vulnerabilities.

Contrasting patterns of somatic mutations in neurons and glia reveal differential predisposition to disease in the aging human brain

Characterizing the mechanisms of somatic mutations in the brain is important for understanding aging and disease, but little is known about the mutational patterns of different cell types. We performed whole-genome sequencing of 71 oligodendrocytes and 51 neurons from neurotypical individuals (0.4 to 104 years old) and identified >67,000 somatic single nucleotide variants (sSNVs) and small insertions and deletions (indels). While both cell types accumulate mutations with age, oligodendrocytes accumulate sSNVs 69% faster than neurons (27/year versus 16/year) whereas indels accumulate 42% slower (1.8/year versus 3.1/year). Correlation with single-cell RNA and chromatin accessibility from the same brains revealed that oligodendrocyte mutations are enriched in inactive genomic regions and are distributed similarly to mutations in brain cancers. In contrast, neuronal mutations are enriched in open, transcriptionally active chromatin. These patterns highlight differences in the mutagenic processes in glia and neurons and suggest cell type-specific, age-related contributions to neurodegeneration and oncogenesis.

The Network of Tumor Microtubes: An Improperly Reactivated Neural Cell Network With Stemness Feature for Resistance and Recurrence in Gliomas

Gliomas are known as an incurable brain tumor for the poor prognosis and robust recurrence. In recent years, a cellular subpopulation with tumor microtubes (TMs) was identified in brain tumors, which may provide a new angle to explain the invasion, resistance, recurrence, and heterogeneity of gliomas. Recently, it was demonstrated that the cell subpopulation also expresses neural stem cell markers and shares a lot of features with both immature neurons and cancer stem cells and may be seen as an improperly reactivated neural cell network with a stemness feature at later time points of life. TMs may also provide a new angle to understand the resistance and recurrence mechanisms of glioma stem cells. In this review, we innovatively focus on the common features between TMs and sprouting axons in morphology, formation, and function. Additionally, we summarized the recent progress in the resistance and recurrence mechanisms of gliomas with TMs and explained the incurability and heterogeneity in gliomas with TMs. Moreover, we discussed the recently discovered overlap between cancer stem cells and TM-positive glioma cells, which may contribute to the understanding of resistant glioma cell subpopulation and the exploration of the new potential therapeutic target for gliomas.

Sox9 directs divergent epigenomic states in brain tumor subtypes

Epigenetic dysregulation is a universal feature of cancer that results in altered patterns of gene expression that drive malignancy. Brain tumors exhibit subtype-specific epigenetic alterations; however, the molecular mechanisms responsible for these diverse epigenetic states remain unclear. Here, we show that the developmental transcription factor Sox9 differentially regulates epigenomic states in high-grade glioma (HGG) and ependymoma (EPN). Using our autochthonous mouse models, we found that Sox9 suppresses HGG growth and expands associated H3K27ac states, while promoting ZFTA-RELA (ZRFUS) EPN growth and diminishing H3K27ac states. These contrasting roles for Sox9 correspond with protein interactions with histone deacetylating complexes in HGG and an association with the ZRFUS oncofusion in EPN. Mechanistic studies revealed extensive Sox9 and ZRFUS promoter co-occupancy, indicating functional synergy in promoting EPN tumorigenesis. Together, our studies demonstrate how epigenomic states are differentially regulated in distinct subtypes of brain tumors, while revealing divergent roles for Sox9 in HGG and EPN tumorigenesis.

A brain precursor atlas reveals the acquisition of developmental-like states in adult cerebral tumours

Human cerebral cancers are known to contain cell types resembling the varying stages of neural development. However, the basis of this association remains unclear. Here, we map the development of mouse cerebrum across the developmental time-course, from embryonic day 12.5 to postnatal day 365, performing single-cell transcriptomics on >100,000 cells. By comparing this reference atlas to single-cell data from >100 glial tumours of the adult and paediatric human cerebrum, we find that tumour cells have an expression signature that overlaps with temporally restricted, embryonic radial glial precursors (RGPs) and their immediate sublineages. Further, we demonstrate that prenatal transformation of RGPs in a genetic mouse model gives rise to adult cerebral tumours that show an embryonic/juvenile RGP identity. Together, these findings implicate the acquisition of embryonic-like states in the genesis of adult glioma, providing insight into the origins of human glioma, and identifying specific developmental cell types for therapeutic targeting.

Elevated GIGYF2 expression suppresses tumor migration and enhances sensitivity to temozolomide in malignant glioma

Glioma is a common type of malignant and aggressive tumor in the brain. Despite progress on mechanistic studies, current understanding of the initiation and progression of glioma remains incomplete. GIGYF2 is a critical regulator in neural development and degeneration, however, its contribution in glioma is not yet elucidated. In this study, using an integrative approach spanning bioinformatic analysis and functional approaches, we explored the potential contribution of GIGYF2 in glioma. Bioinformatic data from public database and our cohort showed that GIGYF2 expression was closely associated with low glioma malignancy and better patient survival. Elevation of GIGYF2 expression impaired cell migration and enhanced temozolomide sensitivity of human glioma cells. We further establish its molecular mechanism by demonstrating that GIGYF2 inhibits MMP-9 mediated cell migration pathway and pro-survival AKT/Bax/Caspase-3 signaling. Our work identifies the suppressive role of GIGYF2 in gliomas, and clarifies the relationship between GIGYF2 expression and glioma malignancy, which may provide a potential target for future interventions.

Identification of hub genes and biological pathways in glioma via integrated bioinformatics analysis

OBJECTIVE

Glioma is the most common intracranial primary malignancy, but its pathogenesis remains unclear.

METHODS

We integrated four eligible glioma microarray datasets from the gene expression omnibus database using the robust rank aggregation method to identify a group of significantly differently expressed genes (DEGs) between glioma and normal samples. We used these DEGs to explore key genes closely associated with glioma survival through weighted gene co-expression network analysis. We then constructed validations of prognosis and survival analyses for the key genes via multiple databases. We also explored their potential biological functions using gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA).

RESULTS

We selected DLGAP5, CDCA8, NCAPH, and CCNB2, as four genes that were abnormally up-regulated in glioma samples, for verification. They showed high levels of isocitrate dehydrogenase gene mutation and tumor grades, as well as good prognostic and diagnostic value for glioma. Their methylation levels were generally lower in glioma samples. GSEA and GSVA analyses suggested the genes were closely involved with glioma proliferation.

CONCLUSION

These findings provide new insights into the pathogenesis of glioma. The hub genes have the potential to be used as diagnostic and therapeutic markers.

Bioinformatics analysis of LMAN1 expression, clinical characteristics, and its effects on cell proliferation and invasion in glioma

Glioma is the most common primary central nervous system malignant tumor with high heterogeneity and poor prognosis. So far, the complex pathological process of glioma has not been fully elucidated, and there is a lack of effective biomarkers for the diagnosis and molecular targeted therapy of glioma. Using bioinformatics methods, 77 upregulated and 89 downregulated differentially expressed genes (DEGs) were detected by intersection analysis in different gene expression datasets of glioma cases from public databases. Then, GO and KEGG pathway analysis revealed that the biological functions of these upregulated DEGs were mainly focused on immune response, and the signaling pathways were mainly enriched in integrin family cell surface interactions. The overexpression of the LMAN1 gene of interest was then confirmed using the TCGA dataset and further verified by qRT-PCR in 29 clinical samples and 5 glioma cell lines. Furthermore, high expression of LMAN1 was found to be associated with higher WHO grade, IDH status, and 1p/19q co-deletion. Survival analysis showed that high expression of LMAN1 was associated with poor prognosis in glioma. Gene set enrichment analysis (GSEA) indicated that many cancer-related pathways were associated with LMAN1-high phenotype. Protein-protein interaction (PPI) analysis revealed significant interaction between LMAN1 and MCFD2, F8, and TMED10. Finally, cell experiments showed that LMAN1 knockdown significantly inhibited the proliferation, migration and invasion and promoted apoptosis in glioma cells. This study highlighted the malignant role of LMAN1 in gliomas and provided a potentially valuable biomarker for prognosis evaluation and molecular targeted therapy of glioma.

A Pyroptosis-Related Gene Signature Associated with Prognosis and Tumor Immune Microenvironment in Gliomas

Background

Pyroptosis is a novel form of cell death that plays a significant role in cancer, while the prognostic values of pyroptosis-related genes in gliomas have not been revealed.

Methods

We analyzed the RNA-seq and clinical data of gliomas from the University of California Santa Cruz (UCSC) Xena database to determine differentially expressed pyroptosis-related genes. Based on these genes, a pyroptosis genes signature was constructed after univariate Cox analysis and Lasso Cox analyses. The sensitivity and specificity of pyroptosis genes signature were verified by the Chinese Glioma Genome Atlas (CGGA) dataset. Finally, we explored the association of risk signatures with tumor microenvironment and immune cell infiltration.

Results

Of 15 differentially expressed pyroptosis-related genes, three genes of BCL2 associated X (BAX), caspase 3 (CASP3), and caspase 4 (CASP4) were used to construct the risk signature. The effectiveness of risk signature for predicting survival at 1, 3, 5 years was performed by the receiver operating characteristic curve (ROC), and the area under curves (AUC) was 0.739, 0.817, and 0.800, respectively. Functional enrichment results showed signal transduction, cell adhesion, immune response, and inflammatory response were enriched. The immune analysis revealed that pyroptosis had a remarkable effect on the immune microenvironment.

Conclusion

In this study, we constructed a pyroptosis-related gene signature, which can serve as a potential biomarker for predicting the survival of glioma patients. Additionally, we suggested that pyroptosis may promote gliomas development by inducing chronic inflammation microenvironment.

Regulation of Neural Differentiation of ADMSCs using Graphene-Mediated Wireless-Localized Electrical Signals Driven by Electromagnetic Induction

Although adipose-derived mesenchymal stem cells (ADMSCs) isolated from patients' fat are considered as the most important autologous stem cells for tissue repair, significant difficulties in the neural differentiation of ADMSCs still impede stem cell therapy for neurodegenerative diseases. Herein, a wireless-electrical stimulation method is proposed to direct the neural differentiation of ADMSCs based on the electromagnetic effect using a graphene film as a conductive scaffold. By placing a rotating magnet on the top of a culture system without any inducer, the ADMSCs cultured on graphene differentiate into functional neurons within 15 days. As a conductive biodegradable nanomaterial, graphene film acts as a wireless electrical signal generator driven by the electromagnetic induction, and millivolt-level voltage generated in situ provokes ADMSCs to differentiate into neurons, proved by morphological variation, extremely high levels of neuron-specific genes, and proteins. Most importantly, Ca2+ intracellular influx is observed in these ADMSC-derived neurons once exposure to neurotransmitters, indicating that these cells are functional neurons. This research enhances stem cell therapy for neurodegenerative diseases using autologous ADMSCs and overcomes the lack of neural stem cells. This nanostructure-mediated physical-signal simulation method is inexpensive, safe, and localized, and has a significant impact on neural regeneration.

LINC00883 Promotes Drug Resistance of Glioma Through a microRNA-136/NEK1-Dependent Mechanism

Objective

Accumulating evidence has highlighted the roles of long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) of microRNAs (miRNAs) through their binding sites in the progression of glioma. Hereby, we aim to explore the role of LINC00883 as a regulator of miR-136 and its target, NIMA-related kinase 1 (NEK1), thus, its involvement in the drug resistance of glioma cells.

Methods and Results

Mechanistic investigations by dual-luciferase reporter, RNA pull-down, and RNA-binding protein immunoprecipitation (RIP) assays indicated that LINC00883 bound to miR-136, thereby blocking miR-136-induced downregulation of NEK1. Through gain-of-function experiments in U251 cells that presented a high drug resistance, we found that ectopic expression of LINC00883 resulted in increased MRP (encoding multidrug resistance-associated protein), limited cell apoptosis, and increased proliferation. Expectedly, depleting LINC00883 yielded tumor-suppressive and anti-chemoresistance effects on U251 cells by increasing miR-136 and inhibiting NEK1. Next, drug-resistant glioma cell line SOWZ1, drug-sensitive glioma cell line SOWZ2, and drug-resistant glioma cell line SOWZ2-BCNU (SOWZ2 cultured in BCNU) were applied to validate the roles of LINC00883 in the regulation of multidrug resistance. LINC00883 knockdown suppressed the viability of SWOZ1, SWOZ2, and SWOZ2-BCNU cells.

Conclusion

In conclusion, LINC00883 knockdown reduces drug resistance in glioma. Hence, our study provides a future strategy to prevent drug resistance-induced therapeutic failure in glioma.

Long noncoding RNA KB-1460A1.5 inhibits glioma tumorigenesis via miR-130a-3p/TSC1/mTOR/YY1 feedback loop

Long noncoding RNAs (lncRNAs) have been shown to be closely related to cancer progression and therapy. However, the clinical significance of lncRNAs and the mechanisms by which they function in glioma are largely unknown. In this study, using online data sets combined with collected clinical glioma tissues, we determined that the lncRNA KB-1460A1.5 is downregulated and positively correlated with prognosis in glioma. Functional experiments showed that overexpression of KB-1460A1.5 inhibits glioma cell proliferation, migration and invasion in vitro and in vivo, while downregulation of KB-1460A1.5 has the opposite effects. Mechanistically, tandem mass tag (TMT)-based quantitative proteomic analysis revealed that KB-1460A1.5 preferentially affects the Akt/TSC1/mTOR pathway. KB-1460A1.5 was found to function as a competing endogenous RNA (ceRNA) to regulate the expression of TSC1, a key regulatory component of the mTOR pathway, by sponging miR-130a-3p in glioma cells. Furthermore, our data demonstrate that the mTOR pathway regulates the expression of the transcription factor Yin Yang 1 (YY1), which in turn binds directly to the KB-1460A1.5 promoter and affects the expression of KB-1460A1.5. Untargeted metabolomics and quantitative real-time PCR (qRT-PCR) analysis further confirmed the effects of KB-1460A1.5 on amino acid metabolism. In conclusion, this study revealed that lncRNA KB-1460A1.5 inhibits glioma tumorigenesis via miR-130a-3p/TSC1/mTOR/YY1 feedback loop.

Circular RNA circFGFR1 Functions as an Oncogene in Glioblastoma Cells through Sponging to hsa-miR-224-5p

Recently, increased studies have shown the important regulatory role of circular RNA (circRNA) in cancer progression and development, including glioblastoma (GBM). However, the function of circRNAs in glioblastoma is still largely unclear. Here, we state that circFGFR1 is elevated in glioma cells, resulting in aggravated glioma aggravated malignancy. The upregulation of circFGFR1 also promotes glioma growth in mouse xenograft models. Furthermore, CXCR4 level in glioma cells is positively correlated with circFGFR1 level, and higher CXCR4 expression is found in circFGFR1 overexpression groups. The effect of circFGFR1 on glioma malignancy is abolished in CXCR4 knockout cells. Then, RIP, RNA pull-down, and luciferase reporter assay results showed that hsa-miR-224-5p directly binds to circFGFR1 and CXCR4 mRNA. The CXCR4 3′-untranslated region (UTR) activated luciferase activity was reduced with hsa-miR-224-5p transfection, while it is reversed when cotransfected with circFGFR1, indicating that circFGFR1 acts as a hsa-miR-244-5p sponge to increase CXCR4 expression. The hsa-miR-224-5p expression is negatively corrected with the glioma malignancy through inhibiting CXCR4 level. Besides, the circFGFR1-induced regulation in glioma malignancy is also abrogated in hsa-miR-224-5p knockout cells. Taken together, our findings suggest that circFGFR1 plays a critical role in the tumorigenic behaviors in glioma cells by upregulating CXCR4 expression via sponging to hsa-miR-224-5p. These findings provide a new perspective on circRNAs during GBM development.

Unraveling unique and common cell type-specific mechanisms in glioblastoma multiforme

Glioblastoma multiforme persists to be an enigmatic distress in neuro-oncology. Its untethering capacity to thrive in a confined microenvironment, metastasize intracranially, and remain resistant to the systemic treatments, renders this tumour incurable. The glial cell type specificity in GBM remains exploratory. In our study, we aimed to address this problem by studying the GBM at the cell type level in the brain. The cellular makeup of this tumour is composed of genetically altered glial cells which include astrocyte, microglia, oligodendrocyte precursor cell, newly formed oligodendrocyte and myelinating oligodendrocyte. We extracted cell type-specific solid tumour as well as recurrent solid tumour glioma genes, and studied their functional networks and contribution towards gliomagenesis. We identified the principal transcription factors that are found to be regulating vital tumorigenic processes. We also assessed the protein-protein interaction networks at their domain level to get a more microscopic view of the structural and functional operations that transpire in these cells. This yielded the eminent protein regulators exhibiting their regulation in signaling pathways. Overall, our study unveiled regulatory mechanisms in glioma cell types that can be targeted for a more efficient glioma therapy.

Glutaredoxin 2 promotes SP-1-dependent CSPG4 transcription and migration of wound healing NG2 glia and glioma cells: Enzymatic Taoism

Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasingly being recognized as an important signaling pathway. Here, we demonstrate that the cytosolic isoform of the vertebrate-specific oxidoreductase Glutaredoxin 2 (Grx2c) regulates the redox state of the transcription factor SP-1 and thereby its binding affinity to both the promoter and an enhancer region of the CSPG4 gene encoding chondroitin sulfate proteoglycan nerve/glial antigen 2 (NG2). This leads to an increased number of NG2 glia during in vitro oligodendroglial differentiation and promotes migration of these wound healing cells. On the other hand, we found that the same mechanism also leads to increased invasion of glioma tumor cells. Using in vitro (human cell lines), ex vivo (mouse primary cells), and in vivo models (zebrafish), as well as glioblastoma patient tissue samples we provide experimental data highlighting the Yin and Yang of redox signaling in the central nervous system and the enzymatic Taoism of Grx2c.

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CSPG4 promoter binding of the transcription factor SP-1 depends on glutaredoxin 2

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Cytosolic glutaredoxin 2 promotes oligodendrocyte differentiation into NG2 glia

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Migration and wound healing capacity of NG2 glia is increased by glutaredoxin 2

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Glutaredoxin 2 increases invasion of human glioblastoma cells in vitro and in vivo

ATRX regulates glial identity and the tumor microenvironment in IDH-mutant glioma

BACKGROUND

Recent single-cell transcriptomic studies report that IDH-mutant gliomas share a common hierarchy of cellular phenotypes, independent of genetic subtype. However, the genetic differences between IDH-mutant glioma subtypes are prognostic, predictive of response to chemotherapy, and correlate with distinct tumor microenvironments.

RESULTS

To reconcile these findings, we profile 22 human IDH-mutant gliomas using scATAC-seq and scRNA-seq. We determine the cell-type-specific differences in transcription factor expression and associated regulatory grammars between IDH-mutant glioma subtypes. We find that while IDH-mutant gliomas do share a common distribution of cell types, there are significant differences in the expression and targeting of transcription factors that regulate glial identity and cytokine elaboration. We knock out the chromatin remodeler ATRX, which suffers loss-of-function alterations in most IDH-mutant astrocytomas, in an IDH-mutant immunocompetent intracranial murine model. We find that both human ATRX-mutant gliomas and murine ATRX-knockout gliomas are more heavily infiltrated by immunosuppressive monocytic-lineage cells derived from circulation than ATRX-intact gliomas, in an IDH-mutant background. ATRX knockout in murine glioma recapitulates gene expression and open chromatin signatures that are specific to human ATRX-mutant astrocytomas, including drivers of astrocytic lineage and immune-cell chemotaxis. Through single-cell cleavage under targets and tagmentation assays and meta-analysis of public data, we show that ATRX loss leads to a global depletion in CCCTC-binding factor association with DNA, gene dysregulation along associated chromatin loops, and protection from therapy-induced senescence.

CONCLUSIONS

These studies explain how IDH-mutant gliomas from different subtypes maintain distinct phenotypes and tumor microenvironments despite a common lineage hierarchy.

miR‑497/MIR497HG inhibits glioma cell proliferation by targeting CCNE1 and the miR‑588/TUSC1 axis

Emerging evidence has shown that microRNA (miR)-497 serves pivotal roles in tumorigenesis, cancer progression, metastasis and chemotherapy resistance in several types of cancer. In the present study, the expression and biological functions of miR-497 host gene (MIR497HG) were investigated in glioma tissue. The expression levels of miR-497 and MIR497HG were measured in glioma, adjacent non-cancerous and normal brain tissue and their association with the prognosis of patients with glioma were analyzed. The biological roles of miR-497 and MIR497HG were investigated in glioma cell lines. In addition, bioinformatics analysis, luciferase reporter assay and functional experiments were performed to identify and validate the downstream targets of miR-497 or MIR497HG. The expression levels of miR-497 and MIR497HG were downregulated in glioma tissue and cell lines compared with those in adjacent non-cancerous and normal brain tissue and normal human cortical neuron cell line. Patients with low miR-497 or MIR497HG expression levels exhibited a poor prognostic outcome. In addition, forced overexpression of miR-497 or MIR497HG significantly inhibited the proliferation and cell cycle progression of glioma cell lines. Furthermore, the results indicated that miR-497 and MIR497HG exerted their biological functions by direct targeting of cyclin E1 and miR-588/tumor suppressor candidate 1. In summary, the data indicated that miR-497 and MIR497HG served as tumor suppressors and may be used as potential therapeutic targets and prognostic biomarkers in glioma.

A Calcium-Related Immune Signature in Prognosis Prediction of Patients With Glioma

Background: Immune checkpoint inhibitors have been successfully used in a variety of tumors, however, the efficacy of immune checkpoint blockade therapy for patients with glioma is limited. In this study, we tried to clarify gene expression signatures related to the prognosis of gliomas and construct a signature to predict the survival of patients with gliomas.

Methods: Calcium-related differential expressed genes (DEGs) between gliomas and normal brain tissues were comprehensively analyzed in two independent databases. Univariate, multivariate Cox regression analysis and proportional hazards model were used to identify the prognostic of calcium-related risk score signature. The CIBERSORT algorithm and association analysis were carried out to evaluate the relationship between calcium-related signature and characteristic clinical features, tumor-infiltrating immune cell signatures as well as immune checkpoint molecules in glioma. A nomogram model was developed for predicting the overall survival for patients with gliomas.

Results: We found the intersection of 415 DEGs between gliomas and normal brain tissues, and identified that an eighteen calcium-related gene panel was significantly enriched in these DEGs. A calcium-related signature derived risk score was developed to divide patients into high- and low-risk groups. Low levels of calcium-related gene expression in high-risk score cases were accompanied with worse outcomes of patients. Calcium-related risk scores were significantly associated with characteristic clinical features, immune infiltrating signatures of tumor microenvironment, and exhausted T cell markers including programmed cell death 1 (PD-1), lymphocyte activating 3 (LAG3), and T cell membrane protein 3 (TIM-3), which contribute to an adverse therapeutic effect of immunotherapy. Calcium-related signature risk score was considered as an independent prognostic parameter to predict the of overall survival of patients with gliomas in nomogram model.

Conclusion: Our study demonstrated that calcium signaling pathway is highly associated with immunosuppression of gliomas and overall survival of patients. Targeting the calcium signaling pathway might be a new strategy to reverse the immunosuppressive microenvironment of gliomas and improve the efficacy of glioma immunotherapy.

Increasing astrogenesis in the developing hippocampus induces autistic-like behavior in mice via enhancing inhibitory synaptic transmission

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized primarily by impaired social communication and rigid, repetitive, and stereotyped behaviors. Many studies implicate abnormal synapse development and the resultant abnormalities in synaptic excitatory–inhibitory (E/I) balance may underlie many features of the disease, suggesting aberrant neuronal connections and networks are prone to occur in the developing autistic brain. Astrocytes are crucial for synaptic formation and function, and defects in astrocytic activation and function during a critical developmental period may also contribute to the pathogenesis of ASD. Here, we report that increasing hippocampal astrogenesis during development induces autistic‐like behavior in mice and a concurrent decreased E/I ratio in the hippocampus that results from enhanced GABAergic transmission in CA1 pyramidal neurons. Suppressing the aberrantly elevated GABAergic synaptic transmission in hippocampal CA1 area rescues autistic‐like behavior and restores the E/I balance. Thus, we provide direct evidence for a developmental role of astrocytes in driving the behavioral phenotypes of ASD, and our results support that targeting the altered GABAergic neurotransmission may represent a promising therapeutic strategy for ASD.

Knockdown of long non-coding RNA SLC8A1-AS1 attenuates cell invasion and migration in glioma via suppression of Wnt/β-catenin signaling pathways

As the most common aggressive malignant tumor in the central nervous system, glioma is still an insurmountable disease in the neural system. The mechanism of carcinogenesis in glioma remains largely unclear. In the present study, we identified a dysregulated long non-coding RNA (lncRNA) solute carrier family 8 member A1 antisense RNA 1 (SLC8A1-AS1) associated with glioma based on The Cancer Genome Atlas (TCGA) data. A validation experiment was conducted to confirm a high expression level of lncRNA SLC8A1-AS1 in glioma tissues. Down-regulation of lncRNA SLC8A1-AS1 suppressed the proliferation, colony formation, migration, and invasion of glioma cells in vitro and in vivo. Moreover, lncRNA SLC8A1-AS1 silencing decreased the activity of the Wnt/β-catenin pathway and suppressed the epithelial to mesenchymal transition (EMT) in glioma cells. These findings collectively provide novel insights into the function and mechanism of lncRNA SLC8A1-AS1 in the pathogenesis of glioma and highlight its potential as a therapeutic target for glioma intervention.

Rates and patterns of clonal oncogenic mutations in the normal human brain

While oncogenic mutations have been found in non-diseased, proliferative non-neural tissues, their prevalence in the human brain is unknown. Targeted sequencing of genes implicated in brain tumors in 418 samples derived from 110 individuals of varying ages, without tumor diagnoses, detected oncogenic somatic single-nucleotide variants (sSNVs) in 5.4% of the brains, including IDH1 R132H. These mutations were largely present in subcortical white matter and enriched in glial cells, and surprisingly, were less common in older individuals. A depletion of high-allele frequency sSNVs representing macroscopic clones with age was replicated by analysis of bulk RNAseq data from 1,816 non-diseased brain samples ranging from fetal to old age. We also describe large clonal copy number variants, and that sSNVs show mutational signatures resembling those found in gliomas, suggesting that mutational processes of the normal brain drive early glial oncogenesis. This study helps understand the origin and early evolution of brain tumors.

Hydroxyapatite Nanorods Function as Safe and Effective Growth Factors Regulating Neural Differentiation and Neuron Development

Neural stem cell (NSC) transplantation is one of the most promising therapeutic strategies for neurodegenerative diseases. However, the slow spontaneous differentiation of NSCs often hampers their application in neural repair. Although some biological growth factors accelerate the differentiation of NSCs, their high cost, short half-life, and unpredictable behavior in vivo, as well as the complexity of the operation, hinder their clinical use. In this study, it is demonstrated that hydroxyapatite (HAp), the main component of bone, in the form of nanorods, can regulate the neural differentiation of NSCs and maturation of the newly differentiated cells. Culturing NSCs with HAp nanorods leads to the differentiation of NSCs into mature neurons that exhibit well-defined electrophysiological behavior within 5 days. The state of these neurons is much better than when culturing the cells without HAp nanorods, which undergo a 2-week differentiation process. Furthermore, RNA-sequencing data reveal that the neuroactive ligand-receptor interaction pathway is dominant in the enriched differentiated neuronal population. Hence, inorganic growth factors like HAp act as a feasible, effective, safe, and practical tool for regulating the differentiation of NSCs and can potentially be used in the treatment of neurodegenerative diseases.

Rare germline variants in the E-cadherin gene CDH1 are associated with the risk of brain tumors of neuroepithelial and epithelial origin

The genetic basis of brain tumor development is poorly understood. Here, leukocyte DNA of 21 patients from 15 families with ≥ 2 glioma cases each was analyzed by whole-genome or targeted sequencing. As a result, we identified two families with rare germline variants, p.(A592T) or p.(A817V), in the E-cadherin gene CDH1 that co-segregate with the tumor phenotype, consisting primarily of oligodendrogliomas, WHO grade II/III, IDH-mutant, 1p/19q-codeleted (ODs). Rare CDH1 variants, previously shown to predispose to gastric and breast cancer, were significantly overrepresented in these glioma families (13.3%) versus controls (1.7%). In 68 individuals from 28 gastric cancer families with pathogenic CDH1 germline variants, brain tumors, including a pituitary adenoma, were observed in three cases (4.4%), a significantly higher prevalence than in the general population (0.2%). Furthermore, rare CDH1 variants were identified in tumor DNA of 6/99 (6%) ODs. CDH1 expression was detected in undifferentiated and differentiating oligodendroglial cells isolated from rat brain. Functional studies using CRISPR/Cas9-mediated knock-in or stably transfected cell models demonstrated that the identified CDH1 germline variants affect cell membrane expression, cell migration and aggregation. E-cadherin ectodomain containing variant p.(A592T) had an increased intramolecular flexibility in a molecular dynamics simulation model. E-cadherin harboring intracellular variant p.(A817V) showed reduced β-catenin binding resulting in increased cytosolic and nuclear β-catenin levels reverted by treatment with the MAPK interacting serine/threonine kinase 1 inhibitor CGP 57380. Our data provide evidence for a role of deactivating CDH1 variants in the risk and tumorigenesis of neuroepithelial and epithelial brain tumors, particularly ODs, possibly via WNT/β-catenin signaling.

ERBB3 overexpression due to miR-205 inactivation confers sensitivity to FGF, metabolic activation, and liability to ERBB3 targeting in glioblastoma

In glioblastoma (GBM), the most frequent and lethal brain tumor, therapies suppressing recurrently altered signaling pathways failed to extend survival. However, in patient subsets, specific genetic lesions can confer sensitivity to targeted agents. By exploiting an integrated model based on patient-derived stem-like cells, faithfully recapitulating the original GBMs in vitro and in vivo, here, we identify a human GBM subset (∼9% of all GBMs) characterized by ERBB3 overexpression and nuclear accumulation. ERBB3 overexpression is driven by inheritable promoter methylation or post-transcriptional silencing of the oncosuppressor miR-205 and sustains the malignant phenotype. Overexpressed ERBB3 behaves as a specific signaling platform for fibroblast growth factor receptor (FGFR), driving PI3K/AKT/mTOR pathway hyperactivation, and overall metabolic upregulation. As a result, ERBB3 inhibition by specific antibodies is lethal for GBM stem-like cells and xenotransplants. These findings highlight a subset of patients eligible for ERBB3-targeted therapy.

NFIA and NFIB function as tumour suppressors in high-grade glioma in mice

Nuclear factor one (NFI) transcription factors are implicated in both brain development and cancer in mice and humans and play an essential role in glial differentiation. NFI expression is reduced in human astrocytoma samples, particularly those of higher grade, whereas over-expression of NFI protein can induce the differentiation of glioblastoma cells within human tumour xenografts and in glioblastoma cell lines in vitro. These data indicate that NFI proteins may act as tumour suppressors in glioma. To test this hypothesis, we generated complex mouse genetic crosses involving six alleles to target gene deletion of known tumour suppressor genes that induce endogenous high-grade glioma in mice, and overlaid this with loss of function Nfi mutant alleles, Nfia and Nfib, a reporter transgene and an inducible Cre allele. Deletion of Nfi resulted in reduced survival time of the mice, increased tumour load and a more aggressive tumour phenotype than observed in glioma mice with normal expression of NFI. Together, these data indicate that NFI genes represent a credible target for both diagnostic analyses and therapeutic strategies to combat high-grade glioma.

The inverse paradigm and the ancestral cell of IDH-wildtype glioblastoma

Rethinking IDH-wildtype glioblastoma through its unique features can help researchers find innovative and effective treatments. It is currently emerging that, after decades of therapeutic impasse, some traditional concepts regarding IDH-wildtype glioblastoma need to be supplemented and updated to overcome therapeutic resistance. Indeed, multiple clinical aspects and recent indirect and direct experimental data are providing evidence that the supratentorial brain parenchyma becomes entirely and quiescently micro-infiltrated long before primary tumor bulk growth. Furthermore, they are indicating that the known micro-infiltration that occurs during the IDH-wildtype glioblastoma growth and evolution is not at the origin of distant relapses. It follows that the ubiquitous supratentorial brain parenchyma micro-infiltration as a source for the development of widespread distant recurrences is actually due to the silent stage that precedes tumor growth rather than to the latter. All this implies that, in addition to the heterogeneity of the primary bulk, there is a second crucial cause of therapeutic resistance that has never hitherto been identified and challenged. In this regard, the ancestral founder cancer stem cell (CSC) appears as the key cell that can link the two causes of resistance.

SOX9-induced Generation of Functional Astrocytes Supporting Neuronal Maturation in an All-human System

Astrocytes, the main supportive cell type of the brain, show functional impairments upon ageing and in a broad spectrum of neurological disorders. Limited access to human astroglia for pre-clinical studies has been a major bottleneck delaying our understanding of their role in brain health and disease. We demonstrate here that functionally mature human astrocytes can be generated by SOX9 overexpression for 6 days in pluripotent stem cell (PSC)-derived neural progenitor cells. Inducible (i)SOX9-astrocytes display functional properties comparable to primary human astrocytes comprising glutamate uptake, induced calcium responses and cytokine/growth factor secretion. Importantly, electrophysiological properties of iNGN2-neurons co-cultured with iSOX9-astrocytes are indistinguishable from gold-standard murine primary cultures. The high yield, fast timing and the possibility to cryopreserve iSOX9-astrocytes without losing functional properties makes them suitable for scaled-up production for high-throughput analyses. Our findings represent a step forward to an all-human iPSC-derived neural model for drug development in neuroscience and towards the reduction of animal use in biomedical research.

TRIM24 promotes stemness and invasiveness of glioblastoma cells via activating Sox2 expression

BACKGROUND

Glioblastoma stem cells (GSCs) are a subpopulation of glioblastoma (GBM) cells that are critical for tumor invasion and treatment resistance. However, little is known about the function and mechanism of tripartite motif-containing 24 (TRIM24) in GSCs.

METHODS

Immunofluorescence, flow cytometry, and western blot analyses were used to evaluate TRIM24 and cluster of differentiation (CD)133 expression profiles in GBM surgical specimens and GSC tumorspheres. Different TRIM24 expression levels in patients' tumors, as measured by both immunohistochemistry and western blot, were related to their corresponding MRI data. Wound healing, Matrigel invasion, and xenograft immunohistochemistry were conducted to determine GBM cell invasion.

RESULTS

We identified that TRIM24 was coexpressed with CD133 and Nestin in GBM tissues and tumorsphere cells. Limiting dilution assays and xenotransplantation experiments illustrated that knockdown of TRIM24 expression reduced GSC self-renewal capacity and invasive growth. TRIM24 expression levels were positively associated with the volumes of peritumoral T2 weighted image abnormality. Rescue experiments indicated TRIM24 participation in GBM infiltrative dissemination. Chromatin immunoprecipitation, reporter gene assay, PCR, western blot, and immunohistochemistry demonstrated that TRIM24 activated the expression of the pluripotency transcription factor sex determining region Y-box 2 (Sox2) to regulate GBM stemness and invasion in vitro and in vivo. Finally, the close relationship between TRIM24 and Sox2 was validated by testing samples enrolled in our study and exploring external databases.

CONCLUSIONS

Our findings uncover essential roles of the TRIM24-Sox2 axis in GBM stemness and invasiveness, suggesting TRIM24 as a potential target for effective GBM management.

Distinguishing Pseudoprogression From True Early Progression in Isocitrate Dehydrogenase Wild-Type Glioblastoma by Interrogating Clinical, Radiological, and Molecular Features

Background: Pseudoprogression (PsP) mimics true early progression (TeP) in conventional imaging, which poses a diagnostic challenge in glioblastoma (GBM) patients who undergo standard concurrent chemoradiation (CCRT). This study aimed to investigate whether perioperative markers could distinguish and predict PsP from TeP in de novo isocitrate dehydrogenase (IDH) wild-type GBM patients.

Methods: New or progressive gadolinium-enhancing lesions that emerged within 12 weeks after CCRT were defined as early progression. Lesions that remained stable or spontaneously regressed were classified as PsP, otherwise persistently enlarged as TeP. Clinical, radiological, and molecular information were collected for further analysis. Patients in the early progression subgroup were divided into derivation and validation sets (7:3, according to operation date).

Results: Among 234 consecutive cases enrolled in this retrospective study, the incidences of PsP, TeP, and neither patterns of progression (nP) were 26.1% (61/234), 37.6% (88/234), and 36.3% (85/234), respectively. In the early progression subgroup, univariate analysis demonstrated female (OR: 2.161, P = 0.026), gross total removal (GTR) of the tumor (OR: 6.571, P < 001), located in the frontal lobe (OR: 2.561, P = 0.008), non-subventricular zone (SVZ) infringement (OR: 10.937, P < 0.001), and methylated O-6-methylguanine-DNA methyltransferase (MGMT) promoter (mMGMTp) (OR: 9.737, P < 0.001) were correlated with PsP, while GTR, non-SVZ infringement, and mMGMTp were further validated in multivariate analysis. Integrating quantitative MGMTp methylation levels from pyrosequencing, GTR, and non-SVZ infringement showed the best discriminative ability in the random forest model for derivation and validation set (AUC: 0.937, 0.911, respectively). Furthermore, a nomogram could effectively evaluate the importance of those markers in developing PsP (C-index: 0.916) and had a well-fitted calibration curve.

Conclusion: Integrating those clinical, radiological, and molecular features provided a novel and robust method to distinguish PsP from TeP, which was crucial for subsequent clinical decision making, clinical trial enrollment, and prognostic assessment. By in-depth interrogation of perioperative markers, clinicians could distinguish PsP from TeP independent from advanced imaging.

A Novel Six-mRNA Signature Predicts Survival of Patients With Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is a devastating brain tumor and displays divergent clinical outcomes due to its high degree of heterogeneity. Reliable prognostic biomarkers are urgently needed for improving risk stratification and survival prediction. In this study, we analyzed genome-wide mRNA profiles in GBM patients derived from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases to identify mRNA-based signatures for GBM prognosis with survival analysis. Univariate Cox regression model was used to evaluate the relationship between the expression of mRNA and the prognosis of patients with GBM. We established a risk score model that consisted of six mRNA (AACS, STEAP1, STEAP2, G6PC3, FKBP9, and LOXL1) by the LASSO regression method. The six-mRNA signature could divide patients into a high-risk and a low-risk group with significantly different survival rates in training and test sets. Multivariate Cox regression analysis confirmed that it was an independent prognostic factor in GBM patients, and it has a superior predictive power as compared with age, IDH mutation status, MGMT, and G-CIMP methylation status. By combining this signature and clinical risk factors, a nomogram can be established to predict 1-, 2-, and 3-year OS in GBM patients with relatively high accuracy.