Circulating glioma biomarkers

Serum beta2-microglobulin acts as a biomarker for severity and prognosis in glioma patients: a preliminary clinical study

BACKGROUND

Gliomas are the deadliest malignant tumors of the adult central nervous system. We previously discovered that beta2-microglobulin (B2M) is abnormally upregulated in glioma tissues and that it exerts a range of oncogenic effects. Besides its tissue presence, serum B2M levels serve as biomarkers for various diseases. This study aimed to explore whether serum B2M levels can be used in the diagnosis and prognosis of gliomas.

METHODS

Medical records from 246 glioma patients were retrospectively analyzed. The relationship between preoperative serum B2M levels and clinicopathological features was examined. Kaplan-Meier analysis, alongside uni- and multivariate Cox regression, assessed the association between B2M levels, systemic inflammatory markers, and glioma patient prognosis. Receiver operating characteristic (ROC) curve analysis evaluated the diagnostic significance of these biomarkers specifically for glioblastoma (GBM).

RESULTS

Patients with malignant gliomas exhibited elevated preoperative serum B2M levels. Glioma patients with high serum B2M levels experienced shorter survival times. Multivariate Cox analysis determined the relationship between B2M levels (hazard ratio = 1.92, 95% confidence interval: 1.05-3.50, P = 0.034) and the overall survival of glioma patients. B2M demonstrated superior discriminatory power in distinguishing between GBM and non-GBM compared to inflammation indicators. Moreover, postoperative serum B2M levels were lower than preoperative levels in the majority of glioma patients.

CONCLUSIONS

High preoperative serum B2M levels correlated with malignant glioma and a poor prognosis. Serum B2M shows promise as a novel biomarker for predicting patient prognosis and reflecting the therapeutic response.

Role of Alpha-Fetoprotein in the Pathogenesis of Cancer

Alpha-fetoprotein (AFP) belongs to the albuminoid protein family and is considered as the fetal analog of serum albumin. This plasma protein is initially synthesized in the fetal liver and yolk sac and shows a maximum peak near the end of the first trimester. Later, concentrations begin to decline prenatally and drop precipitously after birth. This protein has three key ligand-binding pockets for interactions with various biomolecules. It contains multiple phosphorylation and acetylation sites for the regulation of physiological and pathophysiological states. High serum AFP titer is an established biomarker for yolk sac, embryonal and hepatocellular carcinoma. The present review critically analyzes the chemical nature, receptors, clinical implications, and therapeutic aspects of AFP, underpinning the development of different types of cancer.

An untapped window of opportunity for glioma: targeting therapy-induced senescence prior to recurrence

High-grade gliomas are primary brain tumors that are incredibly refractory long-term to surgery and chemoradiation, with no proven durable salvage therapies for patients that have failed conventional treatments. Post-treatment, the latent glioma and its microenvironment are characterized by a senescent-like state of mitotic arrest and a senescence-associated secretory phenotype (SASP) induced by prior chemoradiation. Although senescence was once thought to be irreversible, recent evidence has demonstrated that cells may escape this state and re-enter the cell cycle, contributing to tumor recurrence. Moreover, senescent tumor cells could spur the growth of their non-senescent counterparts, thereby accelerating recurrence. In this review, we highlight emerging evidence supporting the use of senolytic agents to ablate latent, senescent-like cells that could contribute to tumor recurrence. We also discuss how senescent cell clearance can decrease the SASP within the tumor microenvironment thereby reducing tumor aggressiveness at recurrence. Finally, senolytics could improve the long-term sequelae of prior therapy on cognition and bone marrow function. We critically review the senolytic drugs currently under preclinical and clinical investigation and the potential challenges that may be associated with deploying senolytics against latent glioma. In conclusion, senescence in glioma and the microenvironment are critical and potential targets for delaying or preventing tumor recurrence and improving patient functional outcomes through senotherapeutics.

Tissue and plasma free amino acid detection by LC-MS/MS method in high grade glioma patients

PURPOSE

The changes in serum amino acid profiles are evaluated in different types of cancers and screening tests were developed for estimating the risk of cancer by rapid analysis of plasma free amino acid (PFAA) levels. There is scarce evidence about the metabolomics analysis of PFAA in malignant gliomas. The aim of the present study was to identify the most promising diagnostic amino acid biomarkers that could be objectively measured for high-grade glioma and to compare their level with the tissue counterpart.

METHODS

In this prospective study, we collected serum samples from 22 patients with the pathological diagnosis of high-grade diffuse glioma according to WHO 2016 classification and 22 healthy subjects, and brain tissue from 22 controls. Plasma and tissue amino acid concentrations were analyzed applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

RESULTS

Serum alanine, alpha-aminobutyric acid (AABA), lysine (Lys) and cysteine concentrations were significantly higher in high-grade glioma patients despite low levels of alanine and Lys in the tumor tissue. Aspartic acid, histidine and taurine were significantly decreased in both serum and tumors of glioma patients. A positive correlation was detected between tumor volumes and serum levels of latter three amino acids.

CONCLUSION

This study demonstrated potential amino acids which may have diagnostic value for high-grade glioma patients by utilizing LC-MS/MS method. Our results are preliminary to compare serum and tissue levels of amino acids in patients with malignant gliomas. The data presented here may provide feature ideas about the metabolic pathways in the pathogenesis of gliomas.

The Role of Liquid Biopsy in the Diagnosis and Prognosis of WHO Grade 4 Astrocytoma

Liquid biopsy, as a non-invasive diagnostic tool, has recently gained significant attention in the field of oncology. It involves the analysis of various biomarkers present in bodily fluids, such as blood or cerebrospinal fluid, to provide information about the underlying cancer. In the case of WHO grade 4 astrocytomas, liquid biopsy has the potential to significantly impact the diagnosis and prognosis of this aggressive malignant brain tumor. By detecting specific genetic mutations, such as IDH1 or EGFR, and monitoring levels of circulating tumor DNA, liquid biopsy can aid in the early detection and monitoring of disease progression. This innovative approach is gradually being acknowledged as a less invasive and cost-effective procedure for cancer diagnosis and management to improve patient outcomes and quality of life. Various kinds of biomarkers circulating in cerebrospinal fluid (CSF), such as circulating tumor cells (CTC) and different types of nucleic acids like cell-free DNA (cfDNA), cell-free RNA (ctRNA), and microRNAs (miRNA), have been identified. These biomarkers, which require dependable detection methods, are comparatively simple to obtain and allow for repeated measurements, making them significantly superior for disease monitoring. This review aims to compare the latest liquid biopsy analysis tools for both CSF and plasma in the central nervous system.

Exosomes to control glioblastoma multiforme: Investigating the effects of mesenchymal stem cell-derived exosomes on C6 cells in vitro

Glioblastoma multiforme (GBM) is a common, aggressive, fast-growing tumor of the central nervous system that currently has no effective treatment. Although stem cell therapy has shown promising in vitro achievements, the blood-brain barrier (BBB) has always been a major hurdle to clinical success. To overcome this challenge, exosomes have been targeted as attractive drug delivery agents in numerous studies since they are small enough to enter the BBB. Furthermore, exosomes' characteristics and compositions are directly determined by the parent cell and these heritable traits affect their cell interactions. This article focuses on exosomes as an alternative to stem cell therapy to regulate glioma cell activity. Exosomes were isolated from rat bone marrow mesenchymal stem cells (rBMMSCs) by ultracentrifugation method and then characterized via western blot, dynamic light scattering, scanning, and transmission electron microscopy. Next, various concentrations of the exosomes were incubated with C6 cells and their effects at different time points were evaluated in vitro. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Annexin/Pi assay results confirmed that the isolated exosomes cause cell death mostly through apoptosis, and a linear correlation was observed between exosomes' concentration and their cytotoxicity. Following that, the scratch test, colony formation test, and Transwell assay confirmed exosomes' significant impact on the migration and invasion behavior of C6 cells. For the first time, rBMMSC-derived exosomes have been used as a single treatment for GBM rather than in combination with other treatments or as a pharmaceutical carrier.

Non‐hematogenic circulating aneuploid cells confer inferior prognosis and therapeutic resistance in gliomas

Aneuploidy is the hallmark of malignancy. Our previous study successfully detected nonhematogenic circulating aneuploidy cells (CACs) in types of gliomas. The current prospective clinical study aims to further precisely subcategorize aneuploid CACs, including CD31⁻ circulating tumor cells (CTCs) and CD31⁺ circulating tumor endothelial cells, and thoroughly investigate the clinical utilities of these different subtypes of cells. Co‐detection and analysis of CTCs and circulating tumor‐derived endothelial cells (CTECs) expressing CD133, glial fibrillary acidic protein (GFAP), or epidermal growth factor receptor variant III (EGFR vIII) were performed by integrated subtraction enrichment and immunostaining fluorescence in situ hybridization (SE‐iFISH) in 111 preoperative primary diffuse glioma patients. Aneuploid CACs could be detected in most de novo glioma patients. Among detected CACs, 45.6% were CD31⁻/CD45⁻ aneuploid CTCs and the remaining 54.4% were CD31⁺/CD45⁻ aneuploid CTECs. Positive detection of CTECs significantly correlated with disruption of the blood–brain barrier. The median number of large CTCs (_LCTCs, >5 μm, 2) in low‐grade glioma (WHO grade 2) was less than high‐grade glioma (WHO grades 3 and 4) (3, p = 0.044), but this difference was not observed in small CTCs (_SCTCs, ≤5 μm), CTECs or CACs (CTCs + CTECs). The numbers of CTCs, CTECs, or CACs in patients with contrast‐enhancing (CE) lesions considerably exceeded that of non‐CE lesions (p < 0.05). Receiver operating characteristic curves demonstrated that CD31⁺ CTECs, especially _LCTECs, exhibited a close positive relationship with CE lesions. Survival analysis revealed that the high number of CD31⁻ CTCs could be an adverse factor for compromised progression‐free survival and overall survival. Longitudinal surveillance of CD31⁻ CTCs was suitable for evaluating the therapeutic response and for monitoring potential emerging treatment resistance.

Molecular and Circulating Biomarkers in Patients with Glioblastoma

Glioblastoma is the most aggressive malignant tumor of the central nervous system with a low survival rate. The difficulty of obtaining this tumor material represents a major limitation, making the real-time monitoring of tumor progression difficult, especially in the events of recurrence or resistance to treatment. The identification of characteristic biomarkers is indispensable for an accurate diagnosis, the rigorous follow-up of patients, and the development of new personalized treatments. Liquid biopsy, as a minimally invasive procedure, holds promise in this regard. The purpose of this paper is to summarize the current literature regarding the identification of molecular and circulating glioblastoma biomarkers and the importance of their integration as a valuable tool to improve patient care.

Glioma extracellular vesicles for precision medicine: prognostic and theragnostic application

EV produced by tumour cells carry a diverse population of proteins, lipids, DNA, and RNA molecules throughout the body and appear to play an important role in the overall development of the disease state, according to growing data. Gliomas account for a sizable fraction of all primary brain tumours and the vast majority of brain malignancies. Glioblastoma multiforme (GBM) is a kind of grade IV glioma that has a very dismal prognosis despite advancements in diagnostic methods and therapeutic options. The authors discuss advances in understanding the function of extracellular vesicles (EVs), in overall glioma growth, as well as how recent research is uncovering the utility of EVs in glioma diagnostics, prognostic and therapeutics approaches.

Calcium-Related Gene Signatures May Predict Prognosis and Level of Immunosuppression in Gliomas

Gliomas are the most common primary brain cancer. While it has been known that calcium-related genes correlate with gliomagenesis, the relationship between calcium-related genes and glioma prognosis remains unclear. We assessed TCGA datasets of mRNA expressions with differentially expressed genes (DEGs) and enrichment analysis to specifically screen for genes that regulate or are affected by calcium levels. We then correlated the identified calcium-related genes with unsupervised/supervised learning to classify glioma patients into 2 risk groups. We also correlated our identified genes with immune signatures. As a result, we discovered 460 calcium genes and 35 calcium key genes that were associated with OS. There were 13 DEGs between Clusters 1 and 2 with different OS. At the same time, 10 calcium hub genes (CHGs) signature model were constructed using supervised learning, and the prognostic risk scores of the 3 cohorts of samples were calculated. The risk score was confirmed as an independent predictor of prognosis. Immune enrichment analysis revealed an immunosuppressive tumor microenvironment with upregulation of checkpoint markers in the high-risk group. Finally, a nomogram was generated with risk scores and other clinical prognostic independent indicators to quantify prognosis. Our findings suggest that calcium-related gene expression patterns could be applicable to predict prognosis and predict levels of immunosuppression.

Liquid biopsy: early and accurate diagnosis of brain tumor

Noninvasive examination is an emerging area in the field of neuro-oncology. Liquid biopsy captures the landscape of genomic alterations of brain tumors and revolutionizes the traditional diagnosis approaches. Rapidly changing sequencing technologies and more affordable prices put the screws on more application of liquid biopsy in clinical settings. In the past few years, extensive application of liquid biopsy has been seen throughout the whole diagnosis and treatment process of brain tumors, including early and accurate detection, characterization and dynamic monitoring. Here, we summarized and compared the most advanced techniques and target molecules or macrostructures related to brain tumor liquid biopsy. We further reviewed and emphasized recent progression in different clinical settings for brain tumors in blood and CSF. The preferred protocol, potential novel biomarkers and future development are discussed in the last part.

Glioblastoma Microenvironment and Cellular Interactions

Simple Summary

This paper summarizes the crosstalk between tumor/non-tumor cells and other elements of the glioblastoma (GB) microenvironment. In tumor pathology, glial cells result in the highest number of cancers, and GB is considered the most lethal tumor of the central nervous system (CNS). The tumor microenvironment (TME) is a complex peritumoral hallo composed of tumor cells and several non-tumor cells (e.g., nervous cells, stem cells, fibroblasts, vascular and immune cells), which might be a key factor for the ineffective treatment since the microenvironment modulates the biologic status of the tumor with the increase in its evasion capacity. A deeper understanding of cell–cell interactions in the TME and with the tumor cells could be the basis for a more efficient therapy.

Abstract

The central nervous system (CNS) represents a complex network of different cells, such as neurons, glial cells, and blood vessels. In tumor pathology, glial cells result in the highest number of cancers, and glioblastoma (GB) is considered the most lethal tumor in this region. The development of GB leads to the infiltration of healthy tissue through the interaction between all the elements of the brain network. This results in a GB microenvironment, a complex peritumoral hallo composed of tumor cells and several non-tumor cells (e.g., nervous cells, stem cells, fibroblasts, vascular and immune cells), which might be the principal factor for the ineffective treatment due to the fact that the microenvironment modulates the biologic status of the tumor with the increase in its evasion capacity. Crosstalk between glioma cells and the brain microenvironment finally inhibits the beneficial action of molecular pathways, favoring the development and invasion of the tumor and its increasing resistance to treatment. A deeper understanding of cell–cell interactions in the tumor microenvironment (TME) and with the tumor cells could be the basis for a more efficient therapy.

Cell-free DNA technologies for the analysis of brain cancer

Survival for glioma patients has shown minimal improvement over the past 20 years. The ability to detect and monitor gliomas relies primarily upon imaging technologies that lack sensitivity and specificity, especially during the post-surgical treatment phase. Treatment-response monitoring with an effective liquid-biopsy paradigm may also provide the most facile clinical scenario for liquid-biopsy integration into brain-tumour care. Conceptually, liquid biopsy is advantageous when compared with both tissue sampling (less invasive) and imaging (more sensitive and specific), but is hampered by technical and biological problems. These problems predominantly relate to low concentrations of tumour-derived DNA in the bloodstream of glioma patients. In this review, we highlight methods by which the neuro-oncological scientific and clinical communities have attempted to circumvent this limitation. The use of novel biological, technological and computational approaches will be explored. The utility of alternate bio-fluids, tumour-guided sequencing, epigenomic and fragmentomic methods may eventually be leveraged to provide the biological and technological means to unlock a wide range of clinical applications for liquid biopsy in glioma.

Blood Inflammatory Cytokines as Predictors of Depression in Patients With Glioma

BACKGROUND

Depression commonly develops as a comorbid disorder related to glioma, which affects the patients' physical function and prognosis. Circulating inflammatory cytokines are potential predictors of depression in disparate cancers. However, less research has specifically investigated this aspect within the context of glioma.

STUDY OBJECTIVES

The objective of this study was to investigate the occurrence of depression in patients with glioma and draw a comparison of the ability to predict it through diverse inflammatory cytokines.

METHODS

A total of 203 patients with stage I-IV glioma were enrolled in this study. Depression was evaluated according to the Hamilton Depression Scale, and the plasma inflammatory cytokines levels were simultaneously measured. We performed the receiver operating characteristic (ROC) analysis to confirm the abilities of identified inflammatory cytokines to predict depression.

RESULTS

Among the 203 patients with glioma, 135 (66.5%) showed obvious depressive symptoms. Proinflammatory cytokines, including interleukin (IL)-6 (area under the curve (AUC) = 0.76) and tumor necrosis factor (TNF)-α (AUC = 0.75), showed good performance in accurately predicting depression in patients with glioma. These inflammatory cytokines indicated great potential to be depression biomarkers regardless of the patients' disparate treatment experience.

CONCLUSION

With their relatively simple and time-saving measurement procedures, inflammatory cytokines should be seriously considered effective clinical screening and diagnostic tools, as well as potential biomarkers for depression in patients with glioma.

Current landscape of tumor-derived exosomal ncRNAs in glioma progression, detection, and drug resistance

Glioma is the most common and fatal tumor of the central nervous system in humans. Despite advances in surgery, radiotherapy, and chemotherapeutic agents, glioma still has a poor prognosis. The tumor microenvironment (TME) of glioma is of highly complex heterogeneity, which relies on a network-based communication between glioma cells and other stromal cell types. Exosomes are the most common type of naturally occurring extracellular vesicles, ranging in size from 40 to 160 nm, and can serve as carriers for proteins, RNAs, and other biologically active molecules. Recent evidence has shown that glioma-derived exosomes (GDEs) can be integrally detected in the local tissue and circulatory blood samples, and also can be transferred to recipient cells to mediate transmission of genetic information. Non-coding RNAs (ncRNAs) mainly including microRNA, long non-coding RNA, and circular RNA, account for a large portion of the human transcriptome. A broad range of ncRNAs encapsulated in GDEs is reported to exert regulatory functions in various pathophysiological processes of glioma. Herein, this review summarizes the latest findings on the fundamental roles of GDE ncRNAs that have been implicated in glioma behaviors, immunological regulation, diagnosis potential, and treatment resistance, as well as the current limitations and perspectives. Undoubtedly, a thorough understanding of this area will provide comprehensive insights into GDE-based clinical applications for combating gliomas.

Myelin-associated proteins are potential diagnostic markers in patients with primary brain tumour

INTRODUCTION

Taking into account the possibility of myelin-associated proteins having a role in brain tumour development, the study aimed to evaluate the diagnostic usefulness of myelin-associated proteins (Nogo-A, MAG, OMgp) released into extracellular space in patients with brain tumours.

PATIENTS AND METHODS

Protein concentration in primary brain tumour (n = 49) and non-tumoural subjects (n = 24) was measured in cerebrospinal fluid (CSF) and serum by means of ELISA. Immunohistochemistry for IDH1-R132H was done on 5-μm thick formalin-fixed, paraffin-embedded tumour sections with the use of an antibody specific for the mutant IDH1-R132H protein.

RESULTS

The receiver operator characteristic curve analysis showed that CSF Nogo-A and serum MAG were useful in differentiating patients with primary brain tumour from non-tumoural individuals. This was also true in the case of the separate analysis of the astrocytic tumour versus non-tumoural groups and the meningeal tumour versus non-tumoural groups. Neither Nogo-A nor MAG or OMgp concentrations were significantly different, in serum or CSF, between IDH1 wild-type astrocytic brain tumour patients compared to IDH1 mutant patients.

CONCLUSIONS

Our results indicated the potential usefulness of CSF Nogo-A and serum MAG evaluation as circulating biomarkers of primary brain tumours. Because blood is relatively easy to obtain, future research should be conducted to explicitly indicate the value of serum MAG concentration evaluation as a brain tumour biomarker.Key messagesMyelin-associated proteins may be circulating brain tumour biomarkers.Nogo-A and MAG proteins seem to be the most useful in brain tumour diagnosis.Decreased CSF Nogo-A concentration is an adverse prognostic factor for patients' survival.

Fragmentation patterns and personalized sequencing of cell-free DNA in urine and plasma of glioma patients

Glioma-derived cell-free DNA (cfDNA) is challenging to detect using liquid biopsy because quantities in body fluids are low. We determined the glioma-derived DNA fraction in cerebrospinal fluid (CSF), plasma, and urine samples from patients using sequencing of personalized capture panels guided by analysis of matched tumor biopsies. By sequencing cfDNA across thousands of mutations, identified individually in each patient's tumor, we detected tumor-derived DNA in the majority of CSF (7/8), plasma (10/12), and urine samples (10/16), with a median tumor fraction of 6.4 × 10-3 , 3.1 × 10-5 , and 4.7 × 10-5 , respectively. We identified a shift in the size distribution of tumor-derived cfDNA fragments in these body fluids. We further analyzed cfDNA fragment sizes using whole-genome sequencing, in urine samples from 35 glioma patients, 27 individuals with non-malignant brain disorders, and 26 healthy individuals. cfDNA in urine of glioma patients was significantly more fragmented compared to urine from patients with non-malignant brain disorders (P = 1.7 × 10-2 ) and healthy individuals (P = 5.2 × 10-9 ). Machine learning models integrating fragment length could differentiate urine samples from glioma patients (AUC = 0.80-0.91) suggesting possibilities for truly non-invasive cancer detection.

Micro-Raman Characterization of Structural Features of High-k Stack Layer of SOI Nanowire Chip, Designed to Detect Circular RNA Associated with the Development of Glioma

The application of micro-Raman spectroscopy was used for characterization of structural features of the high-k stack (h-k) layer of "silicon-on-insulator" (SOI) nanowire (NW) chip (h-k-SOI-NW chip), including Al₂O₃ and HfO₂ in various combinations after heat treatment from 425 to 1000 °C. After that, the NW structures h-k-SOI-NW chip was created using gas plasma etching optical lithography. The stability of the signals from the monocrine phase of HfO₂ was shown. Significant differences were found in the elastic stresses of the silicon layers for very thick (>200 nm) Al₂O₃ layers. In the UV spectra of SOI layers of a silicon substrate with HfO₂, shoulders in the Raman spectrum were observed at 480-490 cm^-1 of single-phonon scattering. The h-k-SOI-NW chip created in this way has been used for the detection of DNA-oligonucleotide sequences (oDNA), that became a synthetic analog of circular RNA-circ-SHKBP1 associated with the development of glioma at a concentration of 1.1 × 10^-16 M. The possibility of using such h-k-SOI NW chips for the detection of circ-SHKBP1 in blood plasma of patients diagnosed with neoplasm of uncertain nature of the brain and central nervous system was shown.

An integrative analysis of genome-wide 5-hydroxymethylcytosines in circulating cell-free DNA detects noninvasive diagnostic markers for gliomas

Background

Gliomas, especially the high-grade glioblastomas (GBM), are highly aggressive tumors in the central nervous system (CNS) with dismal clinical outcomes. Effective biomarkers, which are not currently available, may improve clinical outcomes through early detection. We sought to develop a noninvasive diagnostic approach for gliomas based on 5-hydroxymethylcytosines (5hmC) in circulating cell-free DNA (cfDNA).

Methods

We obtained genome-wide 5hmC profiles using the 5hmC-Seal technique in cfDNA samples from 111 prospectively enrolled patients with gliomas and 111 age-, gender-matched healthy individuals, which were split into a training set and a validation set. Integrated models comprised 5hmC levels summarized for gene bodies, long noncoding RNAs (lncRNAs), cis-regulatory elements, and repetitive elements were developed using the elastic net regularization under a case-control design.

Results

The integrated 5hmC-based models differentiated healthy individuals from gliomas (area under the curve [AUC] = 84%; 95% confidence interval [CI], 74-93%), GBM patients (AUC = 84%; 95% CI, 74-94%), WHO II-III glioma patients (AUC = 86%; 95% CI, 76-96%), regardless of IDH1 (encoding isocitrate dehydrogenase) mutation status or other glioma-related pathological features such as TERT, TP53 in the validation set. Furthermore, the 5hmC biomarkers in cfDNA showed the potential as an independent indicator from IDH1 mutation status and worked in synergy with IDH1 mutation to distinguish GBM from WHO II-III gliomas. Exploration of the 5hmC biomarkers for gliomas revealed relevance to glioma biology.

Conclusions

The 5hmC-Seal in cfDNA offers the promise as a noninvasive approach for effective detection of gliomas in a screening program.

Circulating Tumor Cells for Glioma

Liquid biopsy has entered clinical applications for several cancers, including metastatic breast, prostate, and colorectal cancer for CTC enumeration and NSCLC for EGFR mutations in ctDNA, and has improved the individualized treatment of many cancers, but relatively little progress has been made in validating circulating biomarkers for brain malignancies. So far, data on circulating tumor cells about glioma are limited, the application of circulating tumor cells as biomarker for glioma patients has only just begun. This article reviews the research status and application prospects of circulating tumor cells in gliomas. Several detection methods and research results of circulating tumor cells about clinical research in gliomas are briefly discussed. The wide application prospect of circulating tumor cells in glioma deserves further exploration, and the research on more sensitive and convenient detection methods is necessary.

KRAS gene polymorphisms are associated with the risk of glioma: a two-center case-control study

BACKGROUND

Glioma, also known as neuroglioma, is the most common primary tumors of the central nervous system. Many previous studies have reported associations between RAS gene polymorphisms and multiple tumors. However, the role of RAS gene polymorphisms on glioma risk has not been investigated.

METHODS

We conducted a two-center case-control study to investigate whether the RAS gene polymorphisms predispose individuals to gliomas in 248 healthy controls and 191 glioma patients. RAS gene polymorphisms (rs12587 G>T, rs7973450 A>G, rs7312175 G>A in KRAS, rs2273267 A>T in NRAS) were genotyped by the TaqMan assay. The relationship between RAS gene functional single nucleotide polymorphisms (SNPs) and the risk of glioma was evaluated based on odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Individuals with KRAS rs7312175 GA genotype were more likely to develop glioma than those with GG genotype (adjusted OR =1.66, 95% CI: 1.05-2.64, P=0.030). However, the other three SNPs could not affect glioma risk. In stratified analysis of age, gender, subtypes, and clinical stages, rs7312175 GA carriers were more likely to develop glioma in the following subgroups: children less than 60 months, tumor derived from the astrocytic tumors, and clinical stages I.

CONCLUSIONS

The study showed that polymorphism rs7312175 GA in the KRAS gene was associated with increased glioma susceptibility. Further investigation is warranted to confirm these findings and to better elucidate the involved biological pathways.

Putting Proteomics Into Immunotherapy for Glioblastoma

In glioblastoma, the most aggressive brain cancer, a complex microenvironment of heterogeneity and immunosuppression, are considerable hurdles to classify the subtypes and promote treatment progression. Treatments for glioblastoma are similar to standard therapies for many other cancers and do not effectively prolong the survival of patients, due to the unique location and heterogeneous characteristics of glioblastoma. Immunotherapy has shown a promising effect for many other tumors, but its application for glioma still has some challenges. The recent breakthrough of high-throughput liquid chromatography-mass spectrometry (LC-MS/MS) systems has allowed researchers to update their strategy for identifying and quantifying thousands of proteins in a much shorter time with lesser effort. The protein maps can contribute to generating a complete map of regulatory systems to elucidate tumor mechanisms. In particular, newly developed unicellular proteomics could be used to determine the microenvironment and heterogeneity. In addition, a large scale of differentiated proteins provides more ways to precisely classify tumor subtypes and construct a larger library for biomarkers and biotargets, especially for immunotherapy. A series of advanced proteomic studies have been devoted to the different aspects of immunotherapy for glioma, including monoclonal antibodies, oncolytic viruses, dendritic cell (DC) vaccines, and chimeric antigen receptor (CAR) T cells. Thus, the application of proteomics in immunotherapy may accelerate research on the treatment of glioblastoma. In this review, we evaluate the frontline applications of proteomics strategies for immunotherapy in glioblastoma research.

Circulating MicroRNAs as Promising Diagnostic Biomarkers for Patients With Glioma: A Meta-Analysis

Backgrounds and Purpose: Currently, circulating microRNAs (miRNAs) are considered to be non-invasive diagnostic biomarkers in a broad range of tumors. Nevertheless, so far, miRNAs have not been fully applied to the clinic for routine screening in glioma patients. Thus, our goal is to evaluate the diagnostic performance of circulating miRNAs for gliomas via a meta-analysis. The present study is registered on the PROSPERO website, with the number CRD42020195883. Methods: Literature retrieval was implemented in the PubMed, Embase, and Web of Science databases using the established search strategy. We pooled the sensitivity, specificity, and its 95% confidence intervals (CIs) for the included studies using the Stata 14.0 software. In addition, the heterogeneity between studies was assessed via the Q statistics and I ² values calculated by a Chi-square test. A bivariate random effects model was selected due to significant heterogeneity. Specifically, for exploring the factors influencing the heterogeneity, we implemented subgroup and meta-regression analyses. Ultimately, a Deek's funnel plot asymmetry test was used to estimate the potential publication bias. Results: A total of 18 articles covering 24 studies were included, containing 2,170 glioma patients and 1,456 healthy participants. The overall pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were 0.84 (95%CI: 0.79-0.87), 0.84 (95%CI: 0.80-0.88), 5.3 (95%CI: 4.1-6.8), 0.19 (95%CI: 0.15-0.25), 27 (95%CI: 18-41), and 0.91 (95%CI: 0.88-0.93), respectively. Additionally, the findings revealed that serum miRNAs and miRNA panels presented superior diagnostic performance. Conclusion: Thus, circulating miRNAs have the potential to serve as diagnostic biomarkers for gliomas, but need to be verified via a large pool of prospective studies. Additionally, specific miRNAs still need to be elucidated in the diagnosis of a glioma, especially in the early screening stage. The findings may provide diagnostic and therapeutic strategies for the glioma population.

Tumor-Educated Platelet RNA for the Detection and (Pseudo)progression Monitoring of Glioblastoma

Tumor-educated platelets (TEPs) are potential biomarkers for cancer diagnostics. We employ TEP-derived RNA panels, determined by swarm intelligence, to detect and monitor glioblastoma. We assessed specificity by comparing the spliced RNA profile of TEPs from glioblastoma patients with multiple sclerosis and brain metastasis patients (validation series, n = 157; accuracy, 80%; AUC, 0.81 [95% CI, 0.74–0.89; p < 0.001]). Second, analysis of patients with glioblastoma versus asymptomatic healthy controls in an independent validation series (n = 347) provided a detection accuracy of 95% and AUC of 0.97 (95% CI, 0.95–0.99; p < 0.001). Finally, we developed the digitalSWARM algorithm to improve monitoring of glioblastoma progression and demonstrate that the TEP tumor scores of individual glioblastoma patients represent tumor behavior and could be used to distinguish false positive progression from true progression (validation series, n = 20; accuracy, 85%; AUC, 0.86 [95% CI, 0.70–1.00; p < 0.012]). In conclusion, TEPs have potential as a minimally invasive biosource for blood-based diagnostics and monitoring of glioblastoma patients.

TEP RNA enables blood-based brain tumor diagnostics

TEP RNA is dynamic throughout anti-tumor treatment

TEP RNA may be employed for therapy monitoring

Analysis of Serum miRNA in Glioblastoma Patients: CD44-Based Enrichment of Extracellular Vesicles Enhances Specificity for the Prognostic Signature

Glioblastoma is a devastating disease, for which biomarkers allowing a prediction of prognosis are urgently needed. microRNAs have been described as potentially valuable biomarkers in cancer. Here, we studied a panel of microRNAs in extracellular vesicles (EVs) from the serum of glioblastoma patients and evaluated their correlation with the prognosis of these patients. The levels of 15 microRNAs in EVs that were separated by size-exclusion chromatography were studied by quantitative real-time PCR, followed by CD44 immunoprecipitation (SEC + CD44), and compared with those from the total serum of glioblastoma patients (n = 55) and healthy volunteers (n = 10). Compared to total serum, we found evidence for the enrichment of miR-21-3p and miR-106a-5p and, conversely, lower levels of miR-15b-3p, in SEC + CD44 EVs. miR-15b-3p and miR-21-3p were upregulated in glioblastoma patients compared to healthy subjects. A significant correlation with survival of the patients was found for levels of miR-15b-3p in total serum and miR-15b-3p, miR-21-3p, miR-106a-5p, and miR-328-3p in SEC + CD44 EVs. Combining miR-15b-3p in serum or miR-106a-5p in SEC + CD44 EVs with any one of the other three microRNAs in SEC + CD44 EVs allowed for a prognostic stratification of glioblastoma patients. We have thus identified four microRNAs in glioblastoma patients whose levels, in combination, can predict the prognosis for these patients.

The Involvement of Exosomes in Glioblastoma Development, Diagnosis, Prognosis, and Treatment

Brain tumours are a serious concern among both physicians and patients. The most feared brain tumour is glioblastoma (GBM) due to its heterogeneous histology, substantial invasive capacity, and rapid postsurgical recurrence. Even in cases of early management consisting of surgery, chemo-, and radiotherapy, the prognosis is still poor, with an extremely short survival period. Consequently, researchers are trying to better understand the underlying pathways involved in GBM development in order to establish a more personalised approach. The latest focus is on molecular characterisation of the tumour, including analysis of extracellular vesicles (EVs), nanostructures derived from both normal and pathological cells that have an important role in intercellular communication due to the various molecules they carry. There are two types of EV based on their biogenesis, but exosomes are of particular interest in GBM. Recent studies have demonstrated that GBM cells release numerous exosomes whose cargo provides them the capacity to facilitate tumour cell invasion and migration, to stimulate malignant transformation of previously normal cells, to increase immune tolerance towards the tumour, to induce resistance to chemotherapy, and to enhance the GBM vascular supply. As exosomes are specific to their parental cells, their isolation would allow a deeper perspective on GBM pathogenesis. A new era of molecular manipulation has emerged, and exosomes are rapidly proving their value not only as diagnostic and prognostic markers, but also as tools in therapies specifically targeting GBM cells. Nonetheless, further research will be required before exosomes could be used in clinical practice. This review aims to describe the structural and functional characteristics of exosomes and their involvement in GBM development, diagnosis, prognosis and treatment.

A Panel of Synapse-Related Genes as a Biomarker for Gliomas

Gliomas are the most common primary brain cancers. In recent years, IDH mutation and 1p/19q codeletion have been suggested as biomarkers for the diagnosis, treatment, and prognosis of gliomas. However, these biomarkers are only effective for a part of glioma patients, and thus more biomarkers are still emergently needed. Recently, an electrochemical communication between normal neurons and glioma cells by neuro-glioma synapse has been reported. Moreover, it was discovered that breast-to-brain metastasis tumor cells have pseudo synapses with neurons, and these synapses were indicated to promote tumor progression and metastasis. Based on the above observations, we first curated a panel of 17 synapse-related genes and then proposed a metric, synapse score to quantify the "stemness" for each sample of 12 glioma gene expression datasets from TCGA, CGGA, and GEO. Strikingly, synapse score showed excellent predictive ability for the prognosis, diagnosis, and grading of gliomas. Moreover, being compared with the two established biomarkers, IDH mutation and 1p/19q codeletion, synapse score demonstrated independent and better predictive performance. In conclusion, this study proposed a quantitative method, synapse score, as an efficient biomarker for monitoring gliomas.

Identification of KIF15 as a potential therapeutic target and prognostic factor for glioma

Glioma is the most commonly diagnosed primary intracranial malignant tumor with rapid growth, easy recurrence and thus poor prognosis. In the present study, the role of kinesin‑12 (KIF15) in glioma was revealed. Immunohistochemical staining and western blot analysis were used to detect the protein expression. An MTT assay was performed to evaluate cell proliferation. Flow cytometric analysis was utilized to assess cell apoptosis and the cell cycle. A mouse xenograft model was constructed for in vivo study. The results indicated that KIF15 was significantly upregulated in glioma tumor tissues and positively correlated with pathological staging, recurrence risk and poor prognosis. Silencing of KIF15 could inhibit cell proliferation and stemness of glioma cells, arrest cells in the G2 phase and induce cell apoptosis. The in vivo study verified the inhibitory effect of KIF15 knockdown on tumor growth. The mechanism study demonstrated the regulation of apoptosis‑ and cycle‑related proteins in the KIF15 KD‑induced inhibition of glioma. KIF15 was revealed to function as a tumor promoter in the development and progression of glioma. KIF15 also served as a prognostic indicator for glioma and may be a therapeutic target for glioma therapy.

Circulating biomarkers in patients with glioblastoma

Gliomas are the most common tumours of the central nervous system and the most aggressive form is glioblastoma (GBM). Despite advances in treatment, patient survival remains low. GBM diagnosis typically relies on imaging techniques and postoperative pathological diagnosis; however, both procedures have their inherent limitations. Imaging modalities cannot differentiate tumour progression from treatment-related changes that mimic progression, known as pseudoprogression, which might lead to misinterpretation of therapy response and delay clinical interventions. In addition to imaging limitations, tissue biopsies are invasive and most of the time cannot be performed over the course of treatment to evaluate 'real-time' tumour dynamics. In an attempt to address these limitations, liquid biopsies have been proposed in the field. Blood sampling is a minimally invasive procedure for a patient to endure and could provide tumoural information to guide therapy. Tumours shed tumoural content, such as circulating tumour cells, cell-free nucleic acids, proteins and extracellular vesicles, into the circulation, and these biomarkers are reported to cross the blood-brain barrier. The use of liquid biopsies is emerging in the field of GBM. In this review, we aim to summarise the current literature on circulating biomarkers, namely circulating tumour cells, circulating tumour DNA and extracellular vesicles as potential non-invasively sampled biomarkers to manage the treatment of patients with GBM.

Measure Twice: Promise of Liquid Biopsy in Pediatric High-Grade Gliomas

Purpose

To review and critique the current state of liquid biopsy in pHGG.

Materials and Methods

Published literature was reviewed for articles related to liquid biopsy in pediatric glioma and adult glioma with a focus on high-grade gliomas.

Results

This review discusses the current state of liquid biomarkers of pHGG and their potential applications for liquid biopsy development.

Conclusions

While nascent, the progress toward identifying circulating analytes of pHGG primes the field of neuro-oncoogy for liquid biopsy development.

Identification of Astrocytoma Blood Serum Protein Profile

High-grade astrocytomas are some of the most common and aggressive brain cancers, whose signs and symptoms are initially non-specific. Up to the present date, there are no diagnostic tools to observe the early onset of the disease. Here, we analyzed the combination of blood serum proteins, which may play key roles in the tumorigenesis and the progression of glial tumors. Fifty-nine astrocytoma patients and 43 control serums were analyzed using Custom Human Protein Antibody Arrays, including ten targets: ANGPT1, AREG, IGF1, IP10, MMP2, NCAM1, OPN, PAI1, TGFβ1, and TIMP1. The decision tree analysis indicates that serums ANGPT1, TIMP1, IP10, and TGFβ1 are promising combinations of targets for glioma diagnostic applications. The accuracy of the decision tree algorithm was 73.5% (75/102), which correctly classified 79.7% (47/59) astrocytomas and 65.1% (28/43) healthy controls. The analysis revealed that the relative value of osteopontin (OPN) protein level alone predicted the 12-month survival of glioblastoma (GBM) patients with the specificity of 84%, while the inclusion of the IP10 protein increased model predictability to 92.3%. In conclusion, the serum protein profiles of ANGPT1, TIMP1, IP10, and TGFβ1 were associated with the presence of astrocytoma independent of its malignancy grade, while OPN and IP10 were associated with GBM patient survival.

A Non-invasive Radiomic Method Using 18F-FDG PET Predicts Isocitrate Dehydrogenase Genotype and Prognosis in Patients With Glioma

Purpose: We aimed to analyze ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) images via the radiomic method to develop a model and validate the potential value of features reflecting glioma metabolism for predicting isocitrate dehydrogenase (IDH) genotype and prognosis.

Methods: PET images of 127 patients were retrospectively analyzed. A series of quantitative features reflecting the metabolic heterogeneity of the tumors were extracted, and a radiomic signature was generated using the support vector machine method. A combined model that included clinical characteristics and the radiomic signature was then constructed by multivariate logistic regression to predict the IDH genotype status, and the model was evaluated and verified by receiver operating characteristic (ROC) curves and calibration curves. Finally, Kaplan-Meier curves and log-rank tests were used to analyze overall survival (OS) according to the predicted result.

Results: The generated radiomic signature was significantly associated with IDH genotype (p < 0.05) and could achieve large areas under the ROC curve of 0.911 and 0.900 on the training and validation cohorts, respectively, with the incorporation of age and type of tumor metabolism. The good agreement of the calibration curves in the validation cohort further validated the efficacy of the constructed model. Moreover, the predicted results showed a significant difference in OS between high- and low-risk groups (p < 0.001).

Conclusions: Our results indicate that the ¹⁸F-FDG metabolism-related features could effectively predict the IDH genotype of gliomas and stratify the OS of patients with different prognoses.

Cerebrospinal fluid VEGF levels and angiogenic capacity as potential prognostic markers in patients with gliomas: a pilot study

INTRODUCTION

Gliomas are tumors of the central nervous system. Despite new classifications, they are still divided in low and high-grade gliomas, being the latter of greater malignancy. The degree of malignancy is directly related with the angiogenic activity in tumoral tissues. We measured VEGF concentrations and angiogenic capacity in cerebrospinal fluid (CSF) from patients with high and low-grade gliomas. The purpose of this study was to find a biomarker that contributes in the differential diagnosis and prognosis of gliomas.

METHODS

CSF was obtained from 19 individuals: 8 with low-grade gliomas, 6 with high-grade gliomas and 5 controls. VEGF concentration in CSF was measured by ELISA and the angiogenic capacity was measured by chick chorioallantoic membrane (CAM) test.

RESULTS

The VEGF concentration was higher in patients with high-grade gliomas, compared to patients with low-grade gliomas and controls (2860 pg/mL ± 975 vs. 182.6 ± 37.1 and 47.4 ± 0.4, respectively). On the other hand, CSF from patients with high-grade gliomas generated a higher microvascular density (MVD) than patients with low-grade gliomas and controls (13.23 ± 0.6 vessels/9000μm² vs. 9.3 ± 0.3 and 7.92 ± 0.2, respectively). Interestingly, there was not statistical differences in both VEGF levels and angiogenic capacity in patients with low-grade gliomas and controls.

CONCLUSION

Together VEGF levels and angiogenic capacity in CSF can be used as a biological marker of gliomas malignancy.

Mapping of genomic EGFRvIII deletions in glioblastoma: insight into rearrangement mechanisms and biomarker development

Background

Epidermal growth factor receptor (EGFR) variant III (vIII) is the most common oncogenic rearrangement in glioblastoma (GBM), generated by deletion of exons 2 to 7 of EGFR. The proximal breakpoints occur in variable positions within the 123-kb intron 1, presenting significant challenges in terms of polymerase chain reaction (PCR)-based mapping. Molecular mechanisms underlying these deletions remain unclear.

Methods

We determined the presence of EGFRvIII and its breakpoints for 29 GBM samples using quantitative PCR, arrayed PCR mapping, Sanger sequencing, and whole genome sequencing (WGS). Patient-specific breakpoint PCR was performed on tumors, plasma, and cerebrospinal fluid (CSF) samples. The breakpoint sequences and single nucleotide polymorphisms (SNPs) were analyzed to elucidate the underlying biogenic mechanism.

Results

PCR mapping and WGS independently unveiled 8 EGFRvIII breakpoints in 6 tumors. Patient-specific primers yielded EGFRvIII PCR amplicons in matched tumors and in cell-free DNA (cfDNA) from a CSF sample, but not in cfDNA or extracellular-vesicle DNA from plasma. The breakpoint analysis revealed nucleotide insertions in 4 samples, an insertion of a region outside of the EGFR locus in 1, microhomologies in 3, as well as a duplication or an inversion accompanied by microhomologies in 2, suggestive of distinct DNA repair mechanisms. In the GBM samples that harbored distinct breakpoints, the SNP compositions of EGFRvIII and amplified non-vIII EGFR were identical, suggesting that these rearrangements arose from amplified non-vIII EGFR.

Conclusion

Our approach efficiently "fingerprints" each sample's EGFRvIII breakpoints. Breakpoint sequence analyses suggest that independent breakpoints arose from precursor amplified non-vIII EGFR through different DNA repair mechanisms.

Immune factors preceding diagnosis of glioma: a Prostate Lung Colorectal Ovarian Cancer Screening Trial nested case-control study

Background

Epidemiological studies of adult glioma have identified genetic and environmental risk factors, but much remains unclear. The aim of the current study was to evaluate anthropometric, disease-related, and prediagnostic immune-related factors for relationship with glioma risk.

Methods

We conducted a nested case–control study among the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial. One hundred and twenty-four glioma cases were identified and each matched to four controls. Baseline characteristics were collected at enrollment and were evaluated for association with glioma status. Serum specimens were collected at yearly intervals and were analyzed for immune-related factors including TGF-β1, TNF-α, total IgE, and allergen-specific IgE. Immune factors were evaluated at baseline in a multivariate conditional logistic regression model, along with one additional model that incorporated the latest available measurement.

Results

A family history of glioma among first-degree relatives was associated with increased glioma risk (OR = 4.41, P = .002). In multivariate modeling of immune factors at baseline, increased respiratory allergen-specific IgE was inversely associated with glioma risk (OR for allergen-specific IgE > 0.35 PAU/L: 0.59, P = .03). A logistic regression model that incorporated the latest available measurements found a similar association for allergen-specific IgE (P = .005) and showed that elevated TGF-β1 was associated with increased glioma risk (P-value for trend <.0001).

Conclusion

The results from this prospective prediagnostic study suggest that several immune-related factors are associated with glioma risk. The association observed for TGF-β1 when sampling closer to the time of diagnosis may reflect the nascent brain tumor’s feedback on immune function.

Current and Future Trends on Diagnosis and Prognosis of Glioblastoma: From Molecular Biology to Proteomics

Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and to develop new personalized treatments. On these bases, the aim of this review article is to summarize the current knowledge regarding the application of molecular biology and proteomics techniques for the identification of novel biomarkers through the analysis of different biological samples obtained from glioblastoma patients, including DNA, microRNAs, proteins, small molecules, circulating tumor cells, extracellular vesicles, etc. Both benefits and pitfalls of molecular biology and proteomics analyses are discussed, including the different mass spectrometry-based analytical techniques, highlighting how these investigation strategies are powerful tools to study the biology of glioblastoma, as well as to develop advanced methods for the management of this pathology.

Pyrosequencing versus methylation-specific PCR for assessment of MGMT methylation in tumor and blood samples of glioblastoma patients

Circulating biomarkers in blood may provide an interesting alternative to risky tissue biopsies in the diagnosis and follow-up of glioblastoma patients. We have assessed MGMT methylation status in blood and tissue samples from unresected glioblastoma patients who had been included in the randomized GENOM-009 trial. Paired blood and tissue samples were assessed by methylation-specific PCR (MSP) and pyrosequencing (PYR). After establishing the minimum PYR cut-off that could yield a significant difference in overall survival, we assessed the sensitivity, specificity, positive predictive value and negative predictive value (NPV) of the analyses. Methylation could be detected in cfDNA by both MSP and PYR but with low concordance with results in tissue. Sensitivity was low for both methods (31% and 38%, respectively), while specificity was higher for MSP in blood than for PYR in plasma (96% vs 76%) and NPV was similar (56 vs 57%). Concordance of results in tissue by MSP and PYR was 84.3% (P < 0.001) and correlated with outcome. We conclude that detection of cfDNA in the blood of glioblastoma patients can be an alternative when tumor tissue is not available but methods for the detection of cfDNA in blood must improve before it can replace analysis in tumor tissue.

lncRNA NEF inhibits glioma by downregulating TGF-β1

NEF is a tumor suppressing long non-coding (lnc)RNA in hepatocellular carcinoma. Based on current literature, the involvement of NEF in other human diseases is still unknown. The current study aimed to investigate the potential involvement of NEF in glioma, which is a type of rare, but aggressive malignancy. It was determined that NEF expression was downregulated in tumor tissues compared with adjacent heathy tissues. A low blood NEF level in patients with glioma effectively distinguished patients from healthy controls who had high blood NEF levels. Blood NEF levels were significantly correlation with distant tumor metastasis, but not tumor growth. Blood NEF levels were negatively correlated with blood transforming growth factor (TGF)-β1 levels in patients with distant tumor metastasis, but not in patients with non-metastatic glioma and healthy controls. NEF overexpression inhibited cancer cell migration and invasion. In addition, NEF overexpression downregulated TGF-β1 expression. The authors of the current study concluded that lncRNA NEF may inhibit glioma cell migration and invasion by downregulating TGF-β1.

lncRNA NEF inhibits glioma by downregulating TGF-β1

NEF is a tumor suppressing long non-coding (lnc)RNA in hepatocellular carcinoma. Based on current literature, the involvement of NEF in other human diseases is still unknown. The current study aimed to investigate the potential involvement of NEF in glioma, which is a type of rare, but aggressive malignancy. It was determined that NEF expression was downregulated in tumor tissues compared with adjacent heathy tissues. A low blood NEF level in patients with glioma effectively distinguished patients from healthy controls who had high blood NEF levels. Blood NEF levels were significantly correlation with distant tumor metastasis, but not tumor growth. Blood NEF levels were negatively correlated with blood transforming growth factor (TGF)-β1 levels in patients with distant tumor metastasis, but not in patients with non-metastatic glioma and healthy controls. NEF overexpression inhibited cancer cell migration and invasion. In addition, NEF overexpression downregulated TGF-β1 expression. The authors of the current study concluded that lncRNA NEF may inhibit glioma cell migration and invasion by downregulating TGF-β1.

Blood-Based Biomarkers in High Grade Gliomas: a Systematic Review

High-grade gliomas (HGG) are the most common malignant primary brain tumor in adults. During the course of disease, several challenges occur, like measuring tumor burden, monitoring of treatment response, estimating the patient's prognosis, and distinguishing between true progression and pseudo-progression. So far, no blood-based biomarker has been established in the clinical routine to address these challenges. The aim of this systematic review was to analyze the present evidence on blood-based biomarkers for HGG. We systematically searched in PubMed, Web of Sciences, Scopus, and Cochrane Library databases for publications before 30th of March 2018 reporting on associations of blood-based biomarkers in HGG patients with different endpoints as overall survival, progression-free survival, and postoperative monitoring. Quality assessment of the studies according to QUIPS and STARD guidelines was performed. In accordance with the GRADE guidelines, level of evidence (I-IV) for each of the tested biomarkers was assessed. One thousand six hundred eighty unique records were identified. Of these, 170 original articles were included to this review. Four hundred fifteen different blood-based biomarkers analyzed in 15.041 patients with HGG as also their corresponding recurrent tumors. Ten predictive biomarkers reached level II of evidence. No biomarker achieved level I of evidence. In this review, 10 blood-based biomarkers were selected as most promising biomarkers for HGG: α2-Heremans-Schmid glycoprotein (AHSG), albumin, glucose, insulin-like growth factor- binding protein 2 (IGFBP-2), macrophage inflammatory protein 1δ (MIP-1 δ), macrophage inflammatory protein 3ß (MIP-3ß), neutrophil-lymphocyte ratio (NLR), red blood cell distribution width (RDW), soluble glycoprotein 130 (Sgp130), and chitinase-3-like protein 1 (YKL-40). To further assess the clinical significance of these biomarkers, the evaluation in a larger cohort of HGG and their corresponding subgroups would be necessary.

Non-Coding RNAs in Glioma

Glioma is the most aggressive brain tumor of the central nervous system. The ability of glioma cells to migrate, rapidly diffuse and invade normal adjacent tissue, their sustained proliferation, and heterogeneity contribute to an overall survival of approximately 15 months for most patients with high grade glioma. Numerous studies indicate that non-coding RNA species have critical functions across biological processes that regulate glioma initiation and progression. Recently, new data emerged, which shows that the cross-regulation between long non-coding RNAs and small non-coding RNAs contribute to phenotypic diversity of glioblastoma subclasses. In this paper, we review data of long non-coding RNA expression, which was evaluated in human glioma tissue samples during a five-year period. Thus, this review summarizes the following: (I) the role of non-coding RNAs in glioblastoma pathogenesis, (II) the potential application of non-coding RNA species in glioma-grading, (III) crosstalk between lncRNAs and miRNAs (IV) future perspectives of non-coding RNAs as biomarkers for glioma.

Probing tumor microenvironment in patients with newly diagnosed glioblastoma during chemoradiation and adjuvant temozolomide with functional MRI

Functional MRI may identify critical windows of opportunity for drug delivery and distinguish between early treatment responders and non-responders. Using diffusion-weighted, dynamic contrast-enhanced, and dynamic susceptibility contrast MRI, as well as pro-angiogenic and pro-inflammatory blood markers, we prospectively studied the physiologic tumor-related changes in fourteen newly diagnosed glioblastoma patients during standard therapy. 153 MRI scans and blood collection were performed before chemoradiation (baseline), weekly during chemoradiation (week 1–6), monthly before each cycle of adjuvant temozolomide (pre-C1-C6), and after cycle 6. The apparent diffusion coefficient, volume transfer coefficient (K^trans), and relative cerebral blood volume (rCBV) and flow (rCBF) were calculated within the tumor and edema regions and compared to baseline. Cox regression analysis was used to assess the effect of clinical variables, imaging, and blood markers on progression-free (PFS) and overall survival (OS). After controlling for additional covariates, high baseline rCBV and rCBF within the edema region were associated with worse PFS (microvessel rCBF: HR = 7.849, p = 0.044; panvessel rCBV: HR = 3.763, p = 0.032; panvessel rCBF: HR = 3.984; p = 0.049). The same applied to high week 5 and pre-C1 K^trans within the tumor region (week 5 K^trans: HR = 1.038, p = 0.003; pre-C1 K^trans: HR = 1.029, p = 0.004). Elevated week 6 VEGF levels were associated with worse OS (HR = 1.034; p = 0.004). Our findings suggest a role for rCBV and rCBF at baseline and K^trans and VEGF levels during treatment as markers of response. Functional imaging changes can differ substantially between tumor and edema regions, highlighting the variable biologic and vascular state of tumor microenvironment during therapy.

Glycerophosphatidylcholine PC(36:1) absence and 3'-phosphoadenylate (pAp) accumulation are hallmarks of the human glioma metabolome

Glioma is the most prevalent malignant brain tumor. A comprehensive analysis of the glioma metabolome is still lacking. This study aims to explore new special metabolites in glioma tissues. A non-targeted human glioma metabolomics was performed by UPLC-Q-TOF/MS. The gene expressions of 18 enzymes associated with 3’-phosphoadenylate (pAp) metabolism was examined by qRT-PCR. Those enzymes cover the primary metabolic pathway of pAp. We identified 15 new metabolites (13 lipids and 2 nucleotides) that were significantly different between the glioma and control tissues. Glycerophosphatidylcholine [PC(36:1)] content was high and pAp content was significantly low in the control brain (p  < 0.01). In glioma tissues, PC(36:1) was not detected and pAp content was significantly increased. The gene expressions of 3′-nucleotidases (Inositol monophosphatase (IMPAD-1) and 3′(2′),5′-bisphosphate nucleotidase 1(BPNT-1)) were dramatically down-regulated. Meanwhile, the gene expression of 8 sulfotransferases (SULT), 2 phosphoadenosine phosphosulfate synthases (PAPSS-1 and PAPSS-2) and L-aminoadipate-semialdehyde dehydrogenase-phosphopante-theinyl transferase (AASDHPPT) were up-regulated. PC(36:1) absence and pAp accumulation are the most noticeable metabolic aberration in glioma. The dramatic down-regulation of IMPAD-1 and BPNT-1 are the primary cause for pAp dramatic accumulation. Our findings suggest that differential metabolites discovered in glioma could be used as potentially novel therapeutic targets or diagnostic biomarkers and that abnormal metabolism of lipids and nucleotides play roles in the pathogenesis of glioma.

Microglia/Astrocytes-Glioblastoma Crosstalk: Crucial Molecular Mechanisms and Microenvironmental Factors

In recent years, the functions of glial cells, namely, astrocytes and microglia, have gained prominence in several diseases of the central nervous system, especially in glioblastoma (GB), the most malignant primary brain tumor that leads to poor clinical outcomes. Studies showed that microglial cells or astrocytes play a critical role in promoting GB growth. Based on the recent findings, the complex network of the interaction between microglial/astrocytes cells and GB may constitute a potential therapeutic target to overcome tumor malignancy. In the present review, we summarize the most important mechanisms and functions of the molecular factors involved in the microglia or astrocytes-GB interactions, which is particularly the alterations that occur in the cell's extracellular matrix and the cytoskeleton. We overview the cytokines, chemokines, neurotrophic, morphogenic, metabolic factors, and non-coding RNAs actions crucial to these interactions. We have also discussed the most recent studies regarding the mechanisms of transportation and communication between microglial/astrocytes - GB cells, namely through the ABC transporters or by extracellular vesicles. Lastly, we highlight the therapeutic challenges and improvements regarding the crosstalk between these glial cells and GB.

Serum amyloid A1 in combination with integrin αVβ3 increases glioblastoma cells mobility and progression

Glioblastoma multiforme (GBM) is a highly malignant type of brain tumor found in humans. GBM cells reproduce quickly, and the median survival time for patients after therapy is approximately 1 year with a high relapse rate. Current therapies and diagnostic tools for GBM are limited; therefore, we searched for a more favorable therapeutic target or marker protein for both therapy and diagnosis. We used mass spectrometry (MS) analysis to identify GBM-associated marker proteins from human plasma and GBM cell cultures. Additional plasma and 52 brain tissues obtained from patients with gliomas were used to validate the association rate of serum amyloid A1 (SAA1) in different grades of gliomas and its distribution in tumors. Microarray database analysis further validated the coefficient of SAA1 levels in gliomas. The cellular mechanisms of SAA1 in GBM proliferation and infiltration were investigated in vitro. We analyzed the correlation between SAA1 and patients' medication requirement to demonstrate the clinical effects of SAA1 in GBM. SAA1 was identified from MS analysis, and its level was revealed to be correlated with the disease grade, clinical severity, and survival rate of patients with gliomas. In vitro cultures, including GBM cells and normal astrocytes, revealed that SAA1 promotes cell migration and invasion through integrin αVβ3 to activate the Erk signaling pathway. Magnetic resonance imaging and tumor region-specific microarray analysis identified a correlation between SAA1 and GBM cell infiltration in patients. In summary, our results demonstrate that SAA1 in combination with integrin αV and β3 can serve as an indicator of high glioblastoma risk. We also identified the cellular mechanisms of SAA1 contributing to GBM progression, which can serve as the basis for future GBM therapy.

Identification of blood biomarkers in glioblastoma by SWATH mass spectrometry and quantitative targeted absolute proteomics

Molecular biomarkers in blood are needed to aid the early diagnosis and clinical assessment of glioblastoma (GBM). Here, in order to identify biomarker candidates in plasma of GBM patients, we performed quantitative comparisons of the plasma proteomes of GBM patients (n = 14) and healthy controls (n = 15) using SWATH mass spectrometry analysis. The results were validated by means of quantitative targeted absolute proteomics analysis. As a result, we identified eight biomarker candidates for GBM (leucine-rich alpha-2-glycoprotein (LRG1), complement component C9 (C9), C-reactive protein (CRP), alpha-1-antichymotrypsin (SERPINA3), apolipoprotein B-100 (APOB), gelsolin (GSN), Ig alpha-1 chain C region (IGHA1), and apolipoprotein A-IV (APOA4)). Among them, LRG1, C9, CRP, GSN, IGHA1, and APOA4 gave values of the area under the receiver operating characteristics curve of greater than 0.80. To investigate the relationships between the biomarker candidates and GBM biology, we examined correlations between plasma concentrations of biomarker candidates and clinical presentation (tumor size, progression-free survival time, or overall survival time) in GBM patients. The plasma concentrations of LRG1, CRP, and C9 showed significant positive correlations with tumor size (R² = 0.534, 0.495, and 0.452, respectively).

Oligodendrocyte Progenitor Cells and Macrophages/Microglia Produce Glioma Stem Cell Niches at the Tumor Border

Glioblastoma (GBM) usually develops in adult brain white matter. Even after complete resection, GBM recurs around the tumor removal cavity, where GBM cells acquire chemo-radioresistance. Characterization of the tumor border microenvironment is critical for improving prognosis in patients with GBM. Here, we compared microRNA (miRNA) expression in samples from the tumor, tumor border, and periphery by miRNA microarray. The top three of miRNAs showing higher expression in the tumor border were related to oligodendrocyte differentiation, and pathologically oligodendrocyte lineage cells were increased in the border, where macrophages and microglia also colocalized. Medium cultured with oligodendrocyte progenitor cells (OPCs) and macrophages induced stemness and chemo-radioresistance in GBM cells, similar to that produced by FGF1, EGF and HB-EGF, IL-1β, corresponding to OPCs and macrophages, respectively. Thus, OPCs and macrophages/microglia may form a glioma stem cell niche at the tumor border, representing a promising target for prevention of recurrence.

•

Most cases of glioblastoma recur in white matter around the removal cavity after total resection plus chemo-radiotherapy.

•

miRNAs showing characteristically higher expression in the tumor border were related to oligodendrocyte differentiation.

•

Increased oligodendrocyte progenitor cells and macrophages enhance stemness and chemo-radioresistance in glioma cells.

Glioblastoma (GBM) occurs in adult brain and shows rapid growth and invasion. Despite intensive treatment, the mean 5-year survival rate is still <10%. Most cases of GBM recur locally even after total resection of gadolinium-enhanced lesions observed with MRI, indicating that chemo-radioresistant GBM cells survive there. MicroRNAs showing characteristically higher expression in the tumor border were related to oligodendrocyte differentiation. Oligodendrocyte progenitor cells (OPCs) and macrophages/microglia increased at tumor borders, and induced stemness and chemo-radioresistance in GBM cells in vivo. Thus, OPCs and macrophages/microglia formed characteristic microenvironments and may be promising targets to prevent GBM recurrence.

The diagnostic value of preoperative inflammatory markers in craniopharyngioma: a multicenter cohort study

To compare the different levels of preoperative inflammatory markers in peripheral blood samples between craniopharyngioma (CP) and other sellar region tumors so as to explore their differential diagnostic value. The level of white blood cell (WBC), neutrophil, lymphocyte, monocyte, platelet, albumin, neutrophil lymphocyte ratio (NLR), derived NLR (dNLR), platelet lymphocyte ratio (PLR), monocyte lymphocyte ratio (MLR) and prognostic nutritional index (PNI) were compared between the CP and other sellar region tumors. A receiver operating characteristics (ROC) curve analysis was performed to evaluate the diagnostic significance of the peripheral blood inflammatory markers and their paired combinations for CP including its pathological types. Patients with CP had higher levels of pre-operative WBC, lymphocyte and PNI. The papillary craniopharyngioma (PCP) group had higher neutrophil count and NLR than the adamantinomatous craniopharyngioma (ACP) and healthy control groups whereas the ACP group had higher platelet count and PNI than the PCP and healthy control groups. There were not any significant differences in preoperative inflammatory markers between the primary and recurrent CP groups. The AUC values of WBC, neutrophil, NLR + PLR and dNLR + PLR in PCP were all higher than 0.7. Inflammation seems to be closely correlated with CP's development. The preoperative inflammatory markers including WBC, neutrophil, NLR + PLR and dNLR + PLR may differentially diagnose PCP, pituitary tumor (PT) and Rathke cleft cyst (RCC). In addition, some statistical results in this study indirectly proved previous experimental conclusions and strictly matched CP's biological features.

Noninvasive Glioblastoma Testing: Multimodal Approach to Monitoring and Predicting Treatment Response

Glioblastoma is the most aggressive adult primary brain tumor which is incurable despite intensive multimodal treatment. Inter- and intratumoral heterogeneity poses one of the biggest barriers in the diagnosis and treatment of glioblastoma, causing differences in treatment response and outcome. Noninvasive prognostic and predictive tests are highly needed to complement the current armamentarium. Noninvasive testing of glioblastoma uses multiple techniques that can capture the heterogeneity of glioblastoma. This set of diagnostic approaches comprises advanced MRI techniques, nuclear imaging, liquid biopsy, and new integrated approaches including radiogenomics and radiomics. New treatment options such as agents targeted at driver oncogenes and immunotherapy are currently being developed, but benefit for glioblastoma patients still has to be demonstrated. Understanding and unraveling tumor heterogeneity and microenvironment can help to create a treatment regime that is patient-tailored to these specific tumor characteristics. Improved noninvasive tests are crucial to this success. This review discusses multiple diagnostic approaches and their effect on predicting and monitoring treatment response in glioblastoma.