Quiescent Adult Neural Stem Cells: Developmental Origin and Regulatory Mechanisms.

The existence of neural stem cells (NSCs) in the adult mammalian nervous system, although small in number and restricted to the sub-ventricular zone of the lateral ventricles, the dentate gyrus of the hippocampus, and the olfactory epithelium, is a gift of evolution for the adaptive brain function which requires persistent plastic changes of these regions. It is known that most adult NSCs are latent, showing long cell cycles. In the past decade, the concept of quiescent NSCs (qNSCs) has been widely accepted by researchers in the field, and great progress has been made in the biology of qNSCs. Although the spontaneous neuronal regeneration derived from adult NSCs is not significant, understanding how the behaviors of qNSCs are regulated sheds light on stimulating endogenous NSC-based neuronal regeneration. In this review, we mainly focus on the recent progress of the developmental origin and regulatory mechanisms that maintain qNSCs under normal conditions, and that mobilize qNSCs under pathological conditions, hoping to give some insights for future study.

Downregulation of microRNA-124-3p promotes subventricular zone neural stem cell activation by enhancing the function of BDNF downstream pathways after traumatic brain injury in adult rats.

AIMS: In this study, the effect of intracerebral ventricle injection with a miR-124-3p agomir or antagomir on prognosis and on subventricular zone (SVZ) neural stem cells (NSCs) in adult rats with moderate traumatic brain injury (TBI) was investigated. METHODS: Model rats with moderate controlled cortical impact (CCI) were established and verified as described previously. The dynamic changes in miR-124-3p and the status of NSCs in the SVZ were analyzed. To evaluate the effect of lateral ventricle injection with miR-124-3p analogs and inhibitors after TBI, modified neurological severity scores (mNSSs) and rotarod tests were used to assess motor function prognosis. The variation in SVZ NSC marker expression was also explored. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of predicted miR-124-3p targets was performed to infer miR-124-3p functions, and miR-124-3p effects on pivotal predicted targets were further explored. RESULTS: Administration of miR-124 inhibitors enhanced SVZ NSC proliferation and improved the motor function of TBI rats. Functional analysis of miR-124 targets revealed high correlations between miR-124 and neurotrophin signaling pathways, especially the TrkB downstream pathway. PI3K, Akt3, and Ras were found to be crucial miR-124 targets and to be involved in most predicted functional pathways. Interference with miR-124 expression in the lateral ventricle affected the PI3K/Akt3 and Ras pathways in the SVZ, and miR-124 inhibitors intensified the potency of brain-derived neurotrophic factor (BDNF) in SVZ NSC proliferation after TBI. CONCLUSION: Disrupting miR-124 expression through lateral ventricle injection has beneficial effects on neuroregeneration and TBI prognosis. Moreover, the combined use of BDNF and miR-124 inhibitors might lead to better outcomes in TBI than BDNF treatment alone.

Clinical and Epidemiological Study of Intracranial Tumors in Children and Identification of Diagnostic Biomarkers for the Most Common Tumor Subtype and Their Relationship with the Immune Microenvironment Through Bioinformatics Analysis.

Brain tumors are the second most common pediatric malignancy and have poor prognosis. Understanding the pathogenesis of tumors at the molecular level is essential for clinical treatment. We conducted a retrospective study on the epidemiology of brain tumors in children based on clinical data obtained from a neurosurgical center. After identifying the most prevalent tumor subtype, we identified new potential diagnostic biomarkers through bioinformatics analysis of the public database. All children (0-15 years) with brain tumors diagnosed histopathologically between 2010 and 2020 at the Department of Neurosurgery, Xijing Hospital, were reviewed retrospectively for age distribution, sex predilection, native location, tumor location, symptoms, and histological grade, and identified the most common tumor subtypes. Two datasets (GSE44971 and GSE44684) were downloaded from the Gene Expression Omnibus database, whereas the GSE44971 dataset was used to screen the differentially expressed genes between normal and tumor samples. Gene ontology, disease ontology, and gene set enrichment analysis enrichment analyses were performed to investigate the underlying mechanisms of differentially expressed genes in the tumor. Combined with methylation data in the GSE44684 dataset, we further analyzed the correlation between methylation and gene expression levels. Two algorithms, LASSO and SVM-RFE, were used to select the hub genes of the tumor. The diagnostic value of the hub genes was assessed using the receiver operating characteristic (ROC) curve. Finally, we further evaluated the relationship between the hub gene and the tumor microenvironment and immune gene sets. Overall, 650 children from 18 provinces in China were included in this study. The male-to-female ratio was 1.41:1, and the number of patients reached a peak in the 10-15-year-old group (41.4%).The most common symptoms we encountered in our institute were headache and dizziness 250 (28.2%), and nausea and vomiting 228 (25.7%). The predominant location is supratentorial, with a supratentorial to infratentorial ratio of 1.74:1. Low-grade tumors (WHO I/II) constituted 60.9% of all cases and were predominant in every age group. According to basic classification, the most common tumor subtype is pilocytic astrocytoma (PA). A total of 3264 differentially expressed genes were identified in the GSE44971 dataset, which are mainly involved in the process of neural signal transduction, immunity, and some diseases. Correlation analysis indicated that the expression of 45 differentially expressed genes was negatively correlated with promoter DNA methylation. Next, we acquired five hub genes (NCKAP1L, GPR37L1, CSPG4, PPFIA4, and C8orf46) from the 45 differentially expressed genes by intersecting the LASSO and SVM-RFE models. The ROC analysis revealed that the five hub genes had good diagnostic value for patients with PA (AUC > 0.99). Furthermore, the expression of NCKAP1L was negatively correlated with immune, stromal, and estimated scores, and positively correlated with immune gene sets. This study, based on the data analysis of intracranial tumors in children in a single center over the past 10 years, reflected the clinical and epidemiological characteristics of intracranial tumors in children in Northwest China to a certain extent. PA is considered the most common subtype of intracranial tumors in children. Through bioinformatics analysis, we suggested that NCKAP1L, GPR37L1, CSPG4, PPFIA4, and C8orf46 are potential biomarkers for the diagnosis of PA.

Identification of key methylation differentially expressed genes in posterior fossa ependymoma based on epigenomic and transcriptome analysis.

BACKGROUND: Posterior fossa ependymoma (EPN-PF) can be classified into Group A posterior fossa ependymoma (EPN-PFA) and Group B posterior fossa ependymoma (EPN-PFB) according to DNA CpG island methylation profile status and gene expression. EPN-PFA usually occurs in children younger than 5 years and has a poor prognosis. METHODS: Using epigenome and transcriptome microarray data, a multi-component weighted gene co-expression network analysis (WGCNA) was used to systematically identify the hub genes of EPN-PF. We downloaded two microarray datasets (GSE66354 and GSE114523) from the Gene Expression Omnibus (GEO) database. The Limma R package was used to identify differentially expressed genes (DEGs), and ChAMP R was used to analyze the differential methylation genes (DMGs) between EPN-PFA and EPN-PFB. GO and KEGG enrichment analyses were performed using the Metascape database. RESULTS: GO analysis showed that enriched genes were significantly enriched in the extracellular matrix organization, adaptive immune response, membrane raft, focal adhesion, NF-kappa B pathway, and axon guidance, as suggested by KEGG analysis. Through WGCNA, we found that MEblue had a significant correlation with EPN-PF (R = 0.69, P = 1 × 10-08) and selected the 180 hub genes in the blue module. By comparing the DEGs, DMGs, and hub genes in the co-expression network, we identified five hypermethylated, lower expressed genes in EPN-PFA (ATP4B, CCDC151, DMKN, SCN4B, and TUBA4B), and three of them were confirmed by IHC. CONCLUSION: ssGSEA and GSVA analysis indicated that these five hub genes could lead to poor prognosis by inducing hypoxia, PI3K-Akt-mTOR, and TNFα-NFKB pathways. Further study of these dysmethylated hub genes in EPN-PF and the pathways they participate in may provides new ideas for EPN-PF treatment.

Acute and chronic infection of H. pylori caused the difference in apoptosis of gastric epithelial cells.

Helicobacter pylori (H. pylori) is one of the most important pathogenic bacteria associated with various gastrointestinal diseases. At present, its apoptotic or antiapoptotic mechanism on gastric epithelial cells remains unknown and needs further illustrated. In this study, acute infection model (H. pylori and GES-1 cells were co-cultured for 24 h at a multiplicity of infection MOI of 100:1) and chronic infection model (GES-1 cells were infected repeatedly every 24 h at a multiplicity of infection MOI of 100:1 for approximately 8 weeks) were established, respectively. the chronic H. pylori infected GES-1 cells underwent a typically morphological change and Western Blot results showed that there was slight decrease in expression of E-cadherin, and obvious increase in expression of Vimentin. Apoptosis of these two models were analyzed by flow cytometry compared with the control cells, meanwhile, apoptosis associated markers (Bcl-xL, Bcl-2, Bax, etc) were detected by Western blot, additional in clinical H. pylori-positive gastric cancer tissues. Results showed that compared with the control cells, acute infection of H. pylori significantly accelerated the apoptosis of GES-1, increased the expression of Bax and Cleaved caspase-3, down-regulated expression of Bcl-xL and Bcl-2. Moreover, an opposite result was found in chronic infection of model and clinical gastric cancer tissues, and enhanced expression of NF-κB p65. Taken together, these findings suggest that H. pylori infection plays differential effects on apoptosis of gastric epithelial cells.

Niche Cells Crosstalk In Neuroinflammation After Traumatic Brain Injury.

Traumatic brain injury (TBI) is recognized as the disease with high morbidity and disability around world in spite of the work ongoing in neural protection. Due to heterogeneity among the patients, it's still hard to acquire satisfying achievements in clinic. Neuroinflammation, which exists since primary injury occurs, with elusive duality, appear to be of significance from recovery of injury to neurogenesis. In recent years, studied have revealed that communication in neurogenic niche is more than "cell to cell" communication, and study on NSCs represent it as central role in the progress of neural regeneration. Hence, the neuroinflammation-affecting crosstalk after TBI, and clarifying definitive role of NSCs in the course of regeneration is a promising subject for researchers, for its great potential in overcoming the frustrating status quo in clinic, promoting welfare of TBI patient.

Toll-Like Receptor 2 Attenuates Traumatic Brain Injury-Induced Neural Stem Cell Proliferation in Dentate Gyrus of Rats.

It was not clear how and whether neural stem cells (NSCs) responded to toll-like receptor 2 (TLR2) in the inflammatory environment after traumatic brain injury (TBI). The current study investigated the correlation of TLR2 and NSC proliferation in the dentate gyrus (DG) using the TBI model of rats. Immunofluorescence (IF) was used to observe the expression of BrdU, nestin, and TLR2 in the DG in morphology. Proliferating cells in the DG were labelled by thymidine analog 5-bromo-2-deoxyuridine (BrdU). Three-labelled BrdU, nestin, and DAPI was used for the identification of newly generated NSCs. Western blotting and real-time polymerase chain reaction (PCR) were used to observe the expression of TLR2 from the level of protein and mRNA. We observed that BrdU+/nestin+/DAPI+ cells accounted for 84.30% ± 6.54% among BrdU+ cells; BrdU+ and nestin+ cells in the DG were also TLR2+ cells. BrdU+ cells and the expression of TLR2 (both protein and mRNA levels) both elevated immediately at 6 hours (h), 24 h, 3 days (d), and 7 d posttrauma and peaked in 3 d. Results indicated that TLR2 was expressed on proliferating cells in the DG (NSCs possibly) and there was a potential correlation between increased TLR2 and proliferated NSCs after TBI. Taken together, these findings suggested that TLR2 was involved in endogenous neurogenesis in the DG after TBI.

The different role of YKL-40 in glioblastoma is a function of MGMT promoter methylation status.

Inter- and intratumoral heterogeneity is a hallmark of glioblastoma (GBM) that facilitates recurrence, treatment resistance, and worse prognosis. O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation is a significant prognostic marker for Temozolomide (TMZ) resistance in GBM patients. YKL-40 is a molecular marker for the mesenchymal subtype of GBMs and is responsible for TMZ resistance. However, underlying mechanisms by which MGMT epigenetics impacts patient outcomes and the function of YKL-40 are not fully determined. Herein, we performed in vitro and in vivo experiments, six human IDH1/2 wild-type glioblastoma stem-like cells (GSCs) were established and studied to further determine a potential interaction of YKL-40 and MGMT promoter methylation. We demonstrated that YKL-40 functioned differently in human IDH1/2 wild-type GSCs. In MGMT promoter-methylated (MGMT-m) GSCs, it acted as a tumor suppressor gene. On the other hand, in MGMT promoter-unmethylated (MGMT-um) GSCs, it promoted tumorigenesis. Notably, the reason that YKL-40 played different roles in GSCs could not be interpreted by the molecular classification of each GSCs, but is a function of MGMT promoter methylation status and involves the RAS-MEK-ERK pathway. YKL-40 mediated TMZ sensitivity by activating DNA damage responses (DDRs) in MGMT-m GSCs, and it mediated resistance to TMZ by inhibiting DDRs in MGMT-um GSCs. Our report demonstrated that MGMT promoter methylation status might influence a gene's function in human cancer. Moreover, our data also highlight the point that gene function should be investigated not only according to the molecular tumor classification, but also the epigenetic signature.

The Effect of SPTLC2 on Promoting Neuronal Apoptosis is Alleviated by MiR-124-3p Through TLR4 Signalling Pathway.

To investigate the role and mechanism of microRNA-124-3p (miR-124-3p) and serine palmitoyltransferase long chain base subunit 2 (SPTLC2) in neuronal apoptosis induced by mechanical injury. Transient transfection was used to modify the expression of miR-124-3p and SPTLC2. After transfection, neuronal apoptosis was evaluated in an in vitro injury model of primary neurons using TUNEL staining and western blot. The correlation between miR-124-3p and SPTLC2 was identified through a dual luciferase reporter assay in HEK293 cells. A rescue experiment in primary neurons was performed to further confirm the result. To explore the downstream mechanisms, co-immunoprecipitation was performed to identify proteins that interact with SPTLC2 in toll-like receptor 4 (TLR4) signalling pathway. Subsequently, the relative expression levels of TLR4 pathway molecules were measured by western blot. Our results showed that increased miR-124-3p can inhibit neuronal apoptosis, which is opposite to the effect of SPTLC2. In addition, miR-124-3p was proved to negatively regulate SPTLC2 expression and suppress the apoptosis-promoting effect of SPTLC2 via the TLR4 signalling pathway.

A five-CpG signature of microRNA methylation in non-G-CIMP glioblastoma.

AIMS: DNA methylation has been found to regulate microRNAs (miRNAs) expression, but the prognostic value of miRNA-related DNA methylation aberration remained largely elusive in cancers including glioblastomas (GBMs). This study aimed to investigate the clinical and biological feature of miRNA methylation in GBMs of non-glioma-CpG island methylator phenotype (non-G-CIMP). METHODS: Prognostic miRNA methylation loci were analyzed, with TCGA and Rennes cohort as training sets, and independent datasets of GBMs and low-grade gliomas (LGGs) were obtained as validation sets. Different statistical and bioinformatic analysis and experimental validations were performed to clinically and biologically characterize the signature. RESULTS: We identified and validated a risk score based on methylation status of five miRNA-associated CpGs which could predict survival of GBM patients in a series of training and validation sets. This signature was independent of age and O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. The risk subgroup was associated with angiogenesis and accordingly differential responses to bevacizumab-contained therapy. MiRNA target analysis and in vitro experiments further confirmed the accuracy of this signature. CONCLUSION: The five-CpG signature of miRNA methylation was biologically relevant and was of potential prognostic and predictive value for GBMs. It might be of help for improving individualized treatment.

Incidence and risk of QTc interval prolongation among cancer patients treated with vandetanib: a systematic review and meta-analysis.

BACKGROUND: Vandetanib is a multikinase inhibitor that is under assessment for the treatment of various cancers. QTc interval prolongation is one of the major adverse effects of this drug, but the reported incidence varies substantially among clinical trials. We performed a systematic review and meta-analysis to obtain a better understanding in the risk of QTc interval prolongation among cancer patients administered vandetanib. METHODOLOGY AND PRINCIPAL FINDINGS: Eligible studies were phase II and III prospective clinical trials that involved cancer patients who were prescribed vandetanib 300 mg/d and that included data on QTc interval prolongation. The overall incidence and risk of QTc interval prolongation were calculated using random-effects or fixed-effects models, depending on the heterogeneity of the included studies. Nine trials with 2,188 patients were included for the meta-analysis. The overall incidence of all-grade and high-grade QTc interval prolongation was 16.4% (95% CI, 8.1-30.4%) and 3.7% (8.1-30.4%), respectively, among non-thyroid cancer patients, and 18.0% (10.7-28.6%) and 12.0% (4.5-28.0%), respectively, among thyroid cancer patients. Patients with thyroid cancer who had longer treatment duration also had a higher incidence of high-grade events, with a relative risk of 3.24 (1.57-6.71), than patients who had non-thyroid cancer. Vandetanib was associated with a significantly increased risk of all-grade QTc interval prolongation with overall Peto odds ratios of 7.26 (4.36-12.09) and 5.70 (3.09-10.53) among patients with non-thyroid cancer and thyroid cancer, respectively, compared to the controls. CONCLUSIONS/SIGNIFICANCE: Treatment with vandetanib is associated with a significant increase in the overall incidence and risk of QTc interval prolongation. Different cancer types and treatment durations may affect the risk of developing high-grade QTc interval prolongation.