Identification of microRNAs in the cerebrospinal fluid as biomarker for the diagnosis of glioma

MicroRNAs: circulating biomarkers for the early detection of imperceptible cancers via biosensor and machine-learning advances

This review explores the topic of microRNAs (miRNAs) for improved early detection of imperceptible cancers, with potential to advance precision medicine and improve patient outcomes. Historical research exploring miRNA's role in cancer detection collectively revealed initial hurdles in identifying specific miRNA signatures for early-stage and difficult-to-detect cancers. Early studies faced challenges in establishing robust biomarker panels and overcoming the heterogeneity of cancer types. Despite this, recent developments have supported the potential of miRNAs as sensitive and specific biomarkers for early cancer detection as well as having demonstrated remarkable potential as diagnostic tools for imperceptible cancers, such as those with elusive symptoms or challenging diagnostic criteria. This review discusses the advent of high-throughput technologies that have enabled comprehensive detection and profiling of unique miRNA signatures associated with early-stage cancers. Furthermore, advancements in bioinformatics and machine-learning techniques are considered, exploring the integration of multi-omics data which have potential to enhance both the accuracy and reliability of miRNA-based cancer detection assays. Finally, perspectives on the continuing development on technologies as well as discussion around challenges that remain, such as the need for standardised protocols and addressing the complex interplay of miRNAs in cancer biology are conferred.

Systematic Review of Cerebrospinal Fluid Biomarker Discovery in Neuro-Oncology: A Roadmap to Standardization and Clinical Application

Effective diagnosis, prognostication, and management of CNS malignancies traditionally involves invasive brain biopsies that pose significant risk to the patient. Sampling and molecular profiling of cerebrospinal fluid (CSF) is a safer, rapid, and noninvasive alternative that offers a snapshot of the intracranial milieu while overcoming the challenge of sampling error that plagues conventional brain biopsy. Although numerous biomarkers have been identified, translational challenges remain, and standardization of protocols is necessary. Here, we systematically reviewed 141 studies (Medline, SCOPUS, and Biosis databases; between January 2000 and September 29, 2022) that molecularly profiled CSF from adults with brain malignancies including glioma, brain metastasis, and primary and secondary CNS lymphomas. We provide an overview of promising CSF biomarkers, propose CSF reporting guidelines, and discuss the various considerations that go into biomarker discovery, including the influence of blood-brain barrier disruption, cell of origin, and site of CSF acquisition (eg, lumbar and ventricular). We also performed a meta-analysis of proteomic data sets, identifying biomarkers in CNS malignancies and establishing a resource for the research community.

Exosomes: Their role in the diagnosis, progression, metastasis, and treatment of glioblastoma

Exosomes are crucial for the growth and spread of glioblastomas, an aggressive form of brain cancer. These tiny vesicles play a crucial role in the activation of signaling pathways and intercellular communication. They can also transfer a variety of biomolecules such as proteins, lipids and nucleic acids from donor to recipient cells. Exosomes can influence the immune response by regulating the activity of immune cells, and they are crucial for the growth and metastasis of glioblastoma cells. In addition, exosomes contribute to drug resistance during treatment, which is a major obstacle in the treatment of glioblastoma. By studying them, the diagnosis and prognosis of glioblastoma can be improved. Due to their high biocompatibility and lack of toxicity, they have become an attractive option for drug delivery. The development of exosomes as carriers of specific therapeutic agents could overcome some of the obstacles to effective treatment of glioblastoma. In this review, we address the potential of exosomes for the treatment of glioblastoma and show how they can be modified for this purpose.

Diagnosis of malignant body fluids via cancer-universal methylation in cell-free DNA

BACKGROUNDDifferentiating malignant from nonmalignant body fluids remains a clinical challenge because of the unsatisfying performance of conventional cytology. We aimed to improve the sensitivity and ubiquity of cancer cell detection by assaying universal cancer-only methylation (UCOM) markers in supernatant cell-free DNA (cfDNA).METHODSAn observational prospective cohort including 1,321 nonmalignant and malignant body fluids of multiple cancers was used to develop and validate a cfDNA UCOM methylation diagnostic assay. All samples were divided into 2 portions for cytology and supernatant cfDNA methylation analysis.RESULTSThe significant hypermethylation of a potentially novel UCOM marker, TAGMe, together with the formerly reported PCDHGB7, was identified in the cfDNA of malignant body fluid samples. The combined model, cell-free cancer-universal methylation (CUE), was developed and validated in a prospective multicancer cohort with markedly elevated sensitivity and specificity, and was further verified in a set containing additional types of malignant body fluids and metastases. In addition, it remained hypersensitive in detecting cancer cells in cytologically negative malignant samples.CONCLUSIONcfDNA methylation markers are robust in detecting tumor cells and are applicable to diverse body fluids and tumor types, providing a feasible complement to current cytology-based diagnostic analyses.TRIAL REGISTRATIONThis study was registered at Chictr.org.cn (ChiCTR2200060532).FUNDINGNational Natural Science Foundation of China (32270645, 31872814, 32000505, 82170088), the National Key R&D Program of Ningxia Hui Autonomous region (2022BEG01003), Shanghai Municipal Key Clinical Specialty (shslczdzk02201), Science and Technology Commission of Shanghai Municipality (20DZ2261200, 20DZ2254400), and Major Special Projects of Basic Research of Shanghai Science and Technology Commission (18JC1411101).

Cerebrospinal Fluid Liquid Biopsies in the Evaluation of Adult Gliomas

PURPOSE OF REVIEW

This review aims to discuss recent research regarding the biomolecules explored in liquid biopsies and their potential clinical uses for adult-type diffuse gliomas.

RECENT FINDINGS

Evaluation of tumor biomolecules via cerebrospinal fluid (CSF) is an emerging technology in neuro-oncology. Studies to date have already identified various circulating tumor DNA, extracellular vesicle, micro-messenger RNA and protein biomarkers of interest. These biomarkers show potential to assist in multiple avenues of central nervous system (CNS) tumor evaluation, including tumor differentiation and diagnosis, treatment selection, response assessment, detection of tumor progression, and prognosis. In addition, CSF liquid biopsies have the potential to better characterize tumor heterogeneity compared to conventional tissue collection and CNS imaging. Current imaging modalities are not sufficient to establish a definitive glioma diagnosis and repeated tissue sampling via conventional biopsy is risky, therefore, there is a great need to improve non-invasive and minimally invasive sampling methods. CSF liquid biopsies represent a promising, minimally invasive adjunct to current approaches which can provide diagnostic and prognostic information as well as aid in response assessment.

MicroRNA as a potential diagnostic and prognostic biomarker in brain gliomas: a systematic review and meta-analysis

Introduction

Brain neoplasms and central nervous system (CNS) disorders, particularly gliomas, have shown a notable increase in incidence over the last three decades, posing significant diagnostic and therapeutic challenges. MicroRNAs (miRNAs) have emerged as promising biomarkers due to their regulatory role in gene expression, offering potential enhancements in glioma diagnosis and prognosis.

Methods

This systematic review and meta-analysis, adhering to PRISMA guidelines, included 25 studies for diagnostic accuracy and 99 for prognostic analysis, published until August 27th, 2023. Studies were identified through comprehensive searches of PubMed, Web of Science, and Scopus databases. Inclusion criteria encompassed peer-reviewed original research providing sensitivity, specificity, and area under the curve (AUC) for miRNAs in glioma diagnosis, as well as survival outcomes with hazard ratios (HRs) or mean survival.

Results and discussion

Meta-analysis demonstrated miRNAs' high diagnostic accuracy, with a pooled sensitivity of 0.821 (95% CI: 0.781-0.855) and specificity of 0.831 (95% CI: 0.792-0.865), yielding an AUC of 0.893. Subgroup analysis by specimen type revealed consistent accuracy across blood, cerebrospinal fluid (CSF), and tissue samples. Our results also showed miRNAs can be potential prognostic biomarkers. miRNAs showed significant associations with overall survival (OS) (pooled HR: 2.0221; 95% CI: 1.8497-2.2105), progression-free survival (PFS) (pooled HR: 2.4248; 95% CI: 1.8888-3.1128), and disease-free survival (DFS) (pooled HR: 1.8973; 95% CI: 1.1637-3.0933) in tissue specimens. These findings underscore miRNAs' potential as valuable biomarkers for improving glioma diagnosis and prognosis, offering insights for enhancing clinical decision-making and patient outcomes.

Liquid biopsy: creating opportunities in brain space

In recent years, liquid biopsy has emerged as an alternative method to diagnose and monitor tumors. Compared to classical tissue biopsy procedures, liquid biopsy facilitates the repetitive collection of diverse cellular and acellular analytes from various biofluids in a non/minimally invasive manner. This strategy is of greater significance for high-grade brain malignancies such as glioblastoma as the quantity and accessibility of tumors are limited, and there are collateral risks of compromised life quality coupled with surgical interventions. Currently, blood and cerebrospinal fluid (CSF) are the most common biofluids used to collect circulating cells and biomolecules of tumor origin. These liquid biopsy analytes have created opportunities for real-time investigations of distinct genetic, epigenetic, transcriptomics, proteomics, and metabolomics alterations associated with brain tumors. This review describes different classes of liquid biopsy biomarkers present in the biofluids of brain tumor patients. Moreover, an overview of the liquid biopsy applications, challenges, recent technological advances, and clinical trials in the brain have also been provided.

Cell-Free miRNAs as Non-Invasive Biomarkers in Brain Tumors

Diagnosing brain tumors, especially malignant variants, such as glioblastoma, medulloblastoma, or brain metastasis, presents a considerable obstacle, while current treatment methods often yield unsatisfactory results. The monitoring of individuals with brain neoplasms becomes burdensome due to the intricate tumor nature and associated risks of tissue biopsies, compounded by the restricted accuracy and sensitivity of presently available non-invasive diagnostic techniques. The uncertainties surrounding diagnosis and the tumor's reaction to treatment can lead to delays in critical determinations that profoundly influence the prognosis of the disease. Consequently, there exists a pressing necessity to formulate and validate dependable, minimally invasive biomarkers that can effectively diagnose and predict brain tumors. Cell-free microRNAs (miRNAs), which remain stable and detectable in human bodily fluids, such as blood and cerebrospinal fluid (CSF), have emerged as potential indicators for a range of ailments, brain tumors included. Numerous investigations have showcased the viability of profiling cell-free miRNA expression in both CSF and blood samples obtained from patients with brain tumors. Distinct miRNAs demonstrate varying expression patterns within CSF and blood. While cell-free microRNAs in the blood exhibit potential in diagnosing, prognosticating, and monitoring treatment across diverse tumor types, they fall short in effectively diagnosing brain tumors. Conversely, the cell-free miRNA profile within CSF demonstrates high potential in delivering precise and specific evaluations of brain tumors.

Micro RNAs as a Diagnostic Marker between Glioma and Primary CNS Lymphoma: A Systematic Review

Differentiating glioma from primary central nervous system lymphoma (PCNSL) can be challenging, and current diagnostic measures such as MRI and biopsy are of limited efficacy. Liquid biopsies, which detect circulating biomarkers such as microRNAs (miRs), may provide valuable insights into diagnostic biomarkers for improved discrimination. This review aimed to investigate the role of specific miRs in diagnosing and differentiating glioma from PCNSL. A systematic search was conducted of PubMed, Scopus, Web of Science, and Embase for articles on liquid biopsies as a diagnostic method for glioma and PCNSL. Sixteen dysregulated miRs were identified with significantly different levels in glioma and PCNSL, including miR-21, which was the most prominent miR with higher levels in PCNSL, followed by glioma, including glioblastoma (GBM), and control groups. The lowest levels of miR-16 and miR-205 were observed in glioma, followed by PCNSL and control groups, whereas miR-15b and miR-301 were higher in both tumor groups, with the highest levels observed in glioma patients. The levels of miR-711 were higher in glioma (including GBM) and downregulated in PCNSL compared to the control group. This review suggests that using these six circulating microRNAs as liquid biomarkers with unique changing patterns could aid in better discrimination between glioma, especially GBM, and PCNSL.

Liquid biopsy and tumor DNA/RNA detection in the cerebrospinal fluid of patients diagnosed with central nervous system glioma - A review article

Background

Gliomas are the most common primary malignant neoplasms of the central nervous system and their characteristic genetic heterogeneity implies in a prominent complexity in their management. The definition of the genetic/molecular profile of gliomas is currently essential for the classification of the disease, prognosis, choice of treatment, and it is still dependent on surgical biopsies, which in many cases become unfeasible. Liquid biopsy with detection and analysis of biomarkers such as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from the tumor and circulating in the bloodstream or cerebrospinal fluid (CSF) has emerged as a minimally invasive alternative to aid in diagnosis, follow-up, and response to treatment of gliomas.

Methods

Through a systematic search in the PubMed MEDLINE, Cochrane Library, and Embase databases, we reviewed the evidence on the use of liquid biopsy to detect tumor DNA/RNA in the CSF of patients diagnosed with central nervous system gliomas.

Results

After a systematic review applying all inclusion and exclusion criteria, as well as a double review by independent authors, 14 studies specifically addressing the detection of tumor DNA/RNA in the CSF of patients diagnosed with central nervous system glioma were selected in the final analysis.

Conclusion

Sensitivity and specificity of liquid biopsy in CSF are still very variable depending on factors such as the diagnostic method, collection timing, biomarker (DNA and RNA), tumor type, extension and volume of the tumor, collection method, and contiguity from neoplasm to CSF. Despite the technical limitations that still exist and prevent the routine and validated use of liquid biopsy in CSF, the growing number of studies around the world is increasingly improving this technic, resulting in promising prospects for its use in diagnosis, evolutionary follow-up, and response to the treatment of complex diseases such as central nervous system gliomas.

Molecular mechanisms of microRNAs in glioblastoma pathogenesis

Glioblastoma (GBM) is human's most prevalent and severe brain cancer. Epigenetic regulators, micro(mi)RNAs, significantly impact cellular health and disease because of their wide range of targets and functions. The "epigenetic symphony" in which miRNAs perform is responsible for orchestrating the transcription of genetic information. The discovery of regulatory miRNA activities in GBM biology has shown that various miRNAs play a vital role in disease onset and development. Here, we summarize our current understanding of the current state-of-the-art and latest findings regarding the interactions between miRNAs and molecular mechanisms commonly associated with GBM pathogenesis. Moreover, by literature review and reconstruction of the GBM gene regulatory network, we uncovered the connection between miRNAs and critical signaling pathways such as cell proliferation, invasion, and cell death, which provides promising hints for identifying potential therapeutic targets for the treatment of GBM. In addition, the role of miRNAs in GBM patient survival was investigated. The present review, which contains new analyses of the previous literature, may lead to new avenues to explore in the future for the development of multitargeted miRNA-based therapies for GBM.

Recent advances in the use of liquid biopsy to fight central nervous system tumors

Brain tumors are considered one of the deadliest types of cancer, being challenging to treat, especially due to the blood-brain barrier, which has been linked to treatment resistance. The genomic classification of brain tumors has been helping in the diagnostic precision, however tumor heterogeneity in addition to the difficulties to obtain tissue biopsies, represent a challenge. The biopsies are usually obtained either via neurosurgical removal or stereotactic tissue biopsy, which can be risky procedures for the patient. To overcome these challenges, liquid biopsy has become an interesting option by constituting a safer procedure than conventional biopsy, which may offer valuable cellular and molecular information representative of the whole organism. Besides, it is relatively easy to obtain such as in the case of blood (venipuncture) and urine sample collection. In the present comprehensive review, we discuss the newest information regarding liquid biopsy in the brain tumors' field, methods employed, the different sources of bio-fluids and their potential circulating targets.

Advances in Brain Metastases Diagnosis: Non-coding RNAs As Potential Biomarkers

Brain metastasis is considered the most common brain tumor. They arise from different primary cancers. The most common primary tumors giving brain metastases include breast, colorectal, lung, melanoma, and renal cancer. Depending only on history, physical examination, and conventional imaging modalities makes brain tumors diagnosis difficult. Rapid and non-invasive promising modalities could diagnose and differentiate between different brain metastases without exposing the patients to unnecessary brain surgeries for biopsies. One of these promising modalities is non-coding RNAs (ncRNAs). NcRNAs can determine brain metastases' prognosis, chemoresistance, and radioresistance. It also helps us to understand the pathophysiology of brain metastases development. Additionally, ncRNAs may work as potential therapeutic targets for brain metastases treatment and prevention. Herein, we present deregulated ncRNAs in different brain metastases, including microRNAs and long non-coding RNAs (lncRNAs), such as gastric adenocarcinoma, colorectal, breast, melanoma, lung, and prostate cancer. Additionally, we focus on serum and cerebrospinal fluid (CSF) expression of these ncRNAs in patients with brain metastases compared to patients with primary tumors. Moreover, we discuss the role of ncRNAs in modulating the immune response in the brain microenvironment. More clinical studies are encouraged to assess the specificity and sensitivity of these ncRNAs.

Liquid biomarkers in glioma

An ideal biomarker must meet several parameters to enable its successful adoption; however, the nature of glioma makes it challenging to discover valuable biomarkers. While biomarkers require simplicity for clinical implementation, anatomical features and the complexity of the brain make it challenging to perform histological examination. Therefore, compared to biomarkers from general histological examination, liquid biomarkers for brain disease offer many more advantages in these minimally invasive methods. Ideal biomarkers should have high sensitivity and specificity, especially in malignant tumors. The heterogeneous nature of glioma makes it challenging to determine useful common biomarkers, and no liquid biomarker has yet been adopted clinically. The low incidence of brain tumors also hinders research progress. To overcome these problems, clinical applications of new types of specimens, such as extracellular vesicles and comprehensive omics analysis, have been developed, and some candidate liquid biomarkers have been identified. As against previous reviews, we focused on and reviewed the sensitivity and specificity of each liquid biomarker for its clinical application. Perusing an ideal glioma biomarker would help uncover the common underlying mechanism of glioma and develop new therapeutic targets. Further multicenter studies based on these findings will help establish new treatment strategies in the future.

microRNAs (miRNAs) in Glioblastoma Multiforme (GBM)-Recent Literature Review

Glioblastoma multiforme (GBM) is the most common, malignant, poorly promising primary brain tumor. GBM is characterized by an infiltrating growth nature, abundant vascularization, and a rapid and aggressive clinical course. For many years, the standard treatment of gliomas has invariably been surgical treatment supported by radio- and chemotherapy. Due to the location and significant resistance of gliomas to conventional therapies, the prognosis of glioblastoma patients is very poor and the cure rate is low. The search for new therapy targets and effective therapeutic tools for cancer treatment is a current challenge for medicine and science. microRNAs (miRNAs) play a key role in many cellular processes, such as growth, differentiation, cell division, apoptosis, and cell signaling. Their discovery was a breakthrough in the diagnosis and prognosis of many diseases. Understanding the structure of miRNAs may contribute to the understanding of the mechanisms of cellular regulation dependent on miRNA and the pathogenesis of diseases underlying these short non-coding RNAs, including glial brain tumors. This paper provides a detailed review of the latest reports on the relationship between changes in the expression of individual microRNAs and the formation and development of gliomas. The use of miRNAs in the treatment of this cancer is also discussed.

Recent advances in label-free optical, electrochemical, and electronic biosensors for glioma biomarkers

Gliomas are the most commonly occurring primary brain tumor with poor prognosis and high mortality rate. Currently, the diagnostic and monitoring options for glioma mainly revolve around imaging techniques, which often provide limited information and require supervisory expertise. Liquid biopsy is a great alternative or complementary monitoring protocol that can be implemented along with other standard diagnosis protocols. However, standard detection schemes for sampling and monitoring biomarkers in different biological fluids lack the necessary sensitivity and ability for real-time analysis. Lately, biosensor-based diagnostic and monitoring technology has attracted significant attention due to several advantageous features, including high sensitivity and specificity, high-throughput analysis, minimally invasive, and multiplexing ability. In this review article, we have focused our attention on glioma and presented a literature survey summarizing the diagnostic, prognostic, and predictive biomarkers associated with glioma. Further, we discussed different biosensory approaches reported to date for the detection of specific glioma biomarkers. Current biosensors demonstrate high sensitivity and specificity, which can be used for point-of-care devices or liquid biopsies. However, for real clinical applications, these biosensors lack high-throughput and multiplexed analysis, which can be achieved via integration with microfluidic systems. We shared our perspective on the current state-of-the-art different biosensor-based diagnostic and monitoring technologies reported and the future research scopes. To the best of our knowledge, this is the first review focusing on biosensors for glioma detection, and it is anticipated that the review will offer a new pathway for the development of such biosensors and related diagnostic platforms.

Fluids and flows in brain cancer and neurological disorders

Interstitial fluid (IF) and cerebrospinal fluid (CSF) are an integral part of the brain, serving to cushion and protect the brain parenchymal cells against damage and aid in their function. The brain IF contains various ions, nutrients, waste products, peptides, hormones, and neurotransmitters. IF moves primarily by pressure-dependent bulk flow through brain parenchyma, draining into the ventricular CSF. The brain ventricles and subarachnoid spaces are filled with CSF which circulates through the perivascular spaces. It also flows into the IF space regulated, in part, by aquaporin channels, removing waste solutes through a process of IF-CSF mixing. During disease development, the composition, flow, and volume of these fluids changes and can lead to brain cell dysfunction. With the improvement of imaging technology and the help of genomic profiling, more information has been and can be obtained from brain fluids; however, the role of CSF and IF in brain cancer and neurobiological disease is still limited. Here we outline recent advances of our knowledge of brain fluid flow in cancer and neurodegenerative disease based on our understanding of its dynamics and composition. This article is categorized under: Cancer > Biomedical Engineering Neurological Diseases > Biomedical Engineering.

Progress of radiological‑pathological workflows in the differential diagnosis between primary central nervous system lymphoma and high‑grade glioma (Review)

Primary central nervous system lymphoma (PCNSL) and high‑grade glioma (HGG) are distinct entities of the CNS with completely distinct treatments. The treatment of PCNSL is chemotherapy‑based, while surgery is the first choice for HGG. However, the clinical features of the two entities often overlap, and a clear pathological diagnosis is important for subsequent management, especially for the management of PCNSL. Stereotactic biopsy is recognized as one of the minimally invasive alternatives for evaluating the involvement of the CNS. However, in the case of limited tissue materials, the differential diagnosis between the two entities is still difficult. In addition, some patients are too ill to tolerate a needle biopsy. Therefore, combining imaging, histopathology and laboratory examinations is essential in order to make a clear diagnosis as soon as possible. The present study reviews the progress of comparative research on both imaging and laboratory tests based on the pathophysiological changes of the two entities, and proposes an integrative and optimized diagnostic process, with the purpose of building a better understanding for neurologists, hematologists, radiologists and pathologists.

Strategies, considerations, and recent advancements in the development of liquid biopsy for glioblastoma: a step towards individualized medicine in glioblastoma

OBJECTIVE

Glioblastoma (GBM) is a devasting primary brain tumor with less than a 5% 5-year survival. Treatment response assessment can be challenging because of inflammatory pseudoprogression that mimics true tumor progression clinically and on imaging. Developing additional noninvasive assays is critical. In this article, the authors review various biomarkers that could be used in developing liquid biopsies for GBM, along with strengths, limitations, and future applications. In addition, they present a potential liquid biopsy design based on the use of an extracellular vesicle-based liquid biopsy targeting nonneoplastic extracellular vesicles.

METHODS

The authors conducted a current literature review of liquid biopsy in GBM by searching the PubMed, Scopus, and Google Scholar databases. Articles were assessed for type of biomarker, isolation methodology, analytical techniques, and clinical relevance.

RESULTS

Recent work has shown that liquid biopsies of plasma, blood, and/or CSF hold promise as noninvasive clinical tools that can be used to diagnose recurrence, assess treatment response, and predict patient outcomes in GBM. Liquid biopsy in GBM has focused primarily on extracellular vesicles, cell-free tumor nucleic acids, and whole-cell isolates as focal biomarkers. GBM tumor signatures have been generated via analysis of tumor gene mutations, unique RNA expression, and metabolic and proteomic alterations. Liquid biopsies capture tumor heterogeneity, identifying alterations in GBM tumors that may be undetectable via surgical biopsy specimens. Finally, biomarker burden can be used to assess treatment response and recurrence in GBM.

CONCLUSIONS

Liquid biopsy offers a promising avenue for monitoring treatment response and recurrence in GBM without invasive procedures. Although additional steps must be taken to bring liquid biopsy into the clinic, proof-of-principle studies and isolation methodologies are promising. Ultimately, CSF and/or plasma-based liquid biopsy is likely to be a powerful tool in the neurosurgeon's arsenal in the near future for the treatment and management of GBM patients.

Thioredoxin System and miR-21, miR-23a/b and let-7a as Potential Biomarkers for Brain Tumor Progression: Preliminary Case Data

BACKGROUND

The thioredoxin system and microRNAs (miRNAs) are potential targets for both cancer progression and treatment. However, the role of miRNAs and their relation with the expression profile of thioredoxin system in brain tumor progression remains unclear.

METHODS

In this study, we aimed to determine the expression profiles of redox components Trx-1, TrxR-1 and PRDX-1, and oncogenic miR-21, miR-23a/b and let-7a and oncosuppressor miR-125 in different brain tumor tissues and their association with increasing tumor grade. We studied Trx-1, TrxR-1, and PRDX-1 messenger RNA expression levels by quantitative real-time polymerase chain reaction and protein levels by Western blot and miR-23a, miR-23b, miR-125a, miR-21, and let-7a miRNA expression levels by quantitative real-time polymerase chain reaction in 16 glioma, 15 meningioma, 5 metastatic, and 2 benign tumor samples. We also examined Trx-1, TrxR-1, and PRDX-1 protein levels in serum samples of 36 patients with brain tumor and 37 healthy volunteers by enzyme-linked immunosorbent assay.

RESULTS

We found that Trx-1, TrxR-1, and PRDX-1 presented high messenger RNA expression but low protein expression in low-grade brain tumor tissues, whereas they showed higher protein expression in sera of patients with low-grade brain tumors. miR-23b, miR-21, miR-23a, and let-7a were highly expressed in low-grade brain tumor tissues and positively correlated with the increase in thioredoxin system activity.

CONCLUSIONS

Our findings showed that Trx-1, TrxR-1, miR-21, miR-23a/b, and let-7a might be used for brain tumor diagnosis in the clinic. Further prospective studies including molecular pathway analyses are required to validate the miRNA/Trx system regulatory axis in brain tumor progression.

The clinical utility of dysregulated microRNA expression in paediatric solid tumours

MicroRNAs (miRNAs) are short, non-protein-coding genes that regulate the expression of numerous protein-coding genes. Their expression is dysregulated in cancer, where they may function as oncogenes or tumour suppressor genes. As miRNAs are highly resistant to degradation, they are ideal biomarker candidates to improve the diagnosis and clinical management of cancer, including prognostication. Furthermore, miRNAs dysregulated in malignancy represent potential therapeutic targets. The use of miRNAs for these purposes is a particularly attractive option to explore for paediatric malignancies, where the mutational burden is typically low, in contrast to cancers affecting adult patients. As childhood cancers are rare, it has taken time to accumulate the necessary body of evidence showing the potential for miRNAs to improve clinical management across this group of tumours. Here, we review the current literature regarding the potential clinical utility of miRNAs in paediatric solid tumours, which is now both timely and justified. Exploring such avenues is warranted to improve the management and outcomes of children affected by cancer.

N6-methyladenosine-related microRNAs risk model trumps the isocitrate dehydrogenase mutation status as a predictive biomarker for the prognosis and immunotherapy in lower grade gliomas

Aim:

Lower grade gliomas [LGGs; World Health Organization (WHO) grades 2 and 3], owing to the heterogeneity of their clinical behavior, present a therapeutic challenge to neurosurgeons. The aim of this study was to explore the N6-methyladenosine (m⁶A) modification landscape in the LGGs and to develop an m⁶A-related microRNA (miRNA) risk model to provide new perspectives for the treatment and prognostic assessment of LGGs.

Methods:

Messenger RNA (mRNA) and miRNA expression data of LGGs were extracted from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. An m⁶A-related miRNA risk model was constructed via least absolute shrinkage and selection operator (LASSO), univariate, and multivariate Cox regression analysis. Next, Kaplan-Meier analysis, principal-component analysis (PCA), functional enrichment analysis, immune infiltrate analysis, dynamic nomogram, and drug sensitivity prediction were used to evaluate this risk model.

Results:

Firstly, six m⁶A-related miRNAs with independent prognostic value were selected based on clinical information and used to construct a risk model. Subsequently, compared with low-risk group, LGGs in the high-risk group had a higher m⁶A writer and reader scores, but a lower eraser score. Moreover, LGGs in the high-risk group had a significantly worse clinical prognosis than those in the low-risk group. Simultaneously, this risk model outperformed other clinicopathological variables in the prognosis prediction of LGGs. Immune infiltrate analysis revealed that the proportion of M2 macrophages, regulatory T (Treg) cells, and the expression levels of exhausted immune response markers were significantly higher in the high-risk group than in the low-risk group. Finally, this study constructed an easy-to-use and free dynamic nomogram to help clinicians use this risk model to aid in diagnosis and prognosis assessment.

Conclusions:

This study developed a m⁶A-related risk model and uncovered two different m⁶A modification landscapes in LGGs. Moreover, this risk model may provide guidance and help in clinical prognosis assessment and immunotherapy response prediction for LGGs.

MicroRNAs as prognostic markers and therapeutic targets in gliomas

Gliomas are invasive brain tumors characterized by high rates of recurrence and mortality. Glioblastoma (GBM), a grade IV brain tumor, is known for its heterogenicity and its resistance to the current treatment regimen. MicroRNA (miRNAs) are small non-coding sequences of RNA that regulate and influence the expression of multiple genes. The detection of certain types of micro-RNA in tissues and blood serum can be used for diagnosis and prognosis, including the response of a particular patient to therapy. The purpose of this review is to analyze studies and experimental results concerning changes in microRNA expression profiles characteristic of gliomas. Furthermore, miRNAs also contribute to autophagy at multiple stages. In this review, we summarize the functions of miRNAs in GBM pathways linked to dysregulation of cell cycle control, apoptosis and resistance to treatment, and the possible use of miRNAs in clinical settings as treatment and prediction biomarkers.

GlioMarker: An integrated database for knowledge exploration of diagnostic biomarkers in gliomas

Gliomas are the most frequent malignant and aggressive tumors in the central nervous system. Early and effective diagnosis of glioma using diagnostic biomarkers can prolong patients' lives and aid in the development of new personalized treatments. Therefore, a thorough and comprehensive understanding of the diagnostic biomarkers in gliomas is of great significance. To this end, we developed the integrated and web-based database GlioMarker (http://gliomarker.prophetdb.org/), the first comprehensive database for knowledge exploration of glioma diagnostic biomarkers. In GlioMarker, accurate information on 406 glioma diagnostic biomarkers from 1559 publications was manually extracted, including biomarker descriptions, clinical information, associated literature, experimental records, associated diseases, statistical indicators, etc. Importantly, we integrated many external resources to provide clinicians and researchers with the capability to further explore knowledge on these diagnostic biomarkers based on three aspects. (1) Obtain more ontology annotations of the biomarker. (2) Identify the relationship between any two or more components of diseases, drugs, genes, and variants to explore the knowledge related to precision medicine. (3) Explore the clinical application value of a specific diagnostic biomarker through online analysis of genomic and expression data from glioma cohort studies. GlioMarker provides a powerful, practical, and user-friendly web-based tool that may serve as a specialized platform for clinicians and researchers by providing rapid and comprehensive knowledge of glioma diagnostic biomarkers to subsequently facilitates high-quality research and applications.

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.

Role of miRNAs in Neurodegeneration: From Disease Cause to Tools of Biomarker Discovery and Therapeutics

Neurodegenerative diseases originate from neuronal loss in the central nervous system (CNS). These debilitating diseases progress with age and have become common due to an increase in longevity. The National Institute of Environmental Health Science’s 2021 annual report suggests around 6.2 million Americans are living with Alzheimer’s disease, and there is a possibility that there will be 1.2 million Parkinson’s disease patients in the USA by 2030. There is no clear-cut universal mechanism for identifying neurodegenerative diseases, and therefore, they pose a challenge for neurobiology scientists. Genetic and environmental factors modulate these diseases leading to familial or sporadic forms. Prior studies have shown that miRNA levels are altered during the course of the disease, thereby suggesting that these noncoding RNAs may be the contributing factor in neurodegeneration. In this review, we highlight the role of miRNAs in the pathogenesis of neurodegenerative diseases. Through this review, we aim to achieve four main objectives: First, we highlight how dysregulation of miRNA biogenesis led to these diseases. Second, we highlight the computational or bioinformatics tools required to identify the putative molecular targets of miRNAs, leading to biological molecular pathways or mechanisms involved in these diseases. Third, we focus on the dysregulation of miRNAs and their target genes leading to several neurodegenerative diseases. In the final section, we highlight the use of miRNAs as potential diagnostic biomarkers in the early asymptomatic preclinical diagnosis of these age-dependent debilitating diseases. Additionally, we discuss the challenges and advances in the development of miRNA therapeutics for brain targeting. We list some of the innovative strategies employed to deliver miRNA into target cells and the relevance of these viral and non-viral carrier systems in RNA therapy for neurodegenerative diseases. In summary, this review highlights the relevance of studying brain-enriched miRNAs, the mechanisms underlying their regulation of target gene expression, their dysregulation leading to progressive neurodegeneration, and their potential for biomarker marker and therapeutic intervention. This review thereby highlights ways for the effective diagnosis and prevention of these neurodegenerative disorders in the near future.

Liquid biopsy: the value of different bodily fluids

Liquid biopsies have gained an increasing interest in the last years among medical and scientific communities. Indeed, the value of liquid effusions, while less invasive and more accurate techniques, has been markedly highlighted. Peripheral blood comprises the most often analyzed sample, but recent evidences have pointed out the huge importance of other bodily fluids, including pleural and peritoneal fluids, urine, saliva and cerebrospinal fluid in the detection and monitoring of different tumor types. In face to these advances, this review aims to provide an overview of the value of tumor-associated mutations, detectable in different effusions, and how they can be used in clinical practice, namely in prognosis assessment and early disease and minimal disease recurrence detection, and in predicting the treatment response or acquired-resistance development.

The Study of Cerebrospinal Fluid microRNAs in Spinal Cord Injury and Neurodegenerative Diseases: Methodological Problems and Possible Solutions

Despite extensive research on neurological disorders, unanswered questions remain regarding the molecular mechanisms underpinning the course of these diseases, and the search continues for effective biomarkers for early diagnosis, prognosis, or therapeutic intervention. These questions are especially acute in the study of spinal cord injury (SCI) and neurodegenerative diseases. It is believed that the changes in gene expression associated with processes triggered by neurological disorders are the result of post-transcriptional gene regulation. microRNAs (miRNAs) are key regulators of post-transcriptional gene expression and, as such, are often looked to in the search for effective biomarkers. We propose that cerebrospinal fluid (CSF) is potentially a source of biomarkers since it is in direct contact with the central nervous system and therefore may contain biomarkers indicating neurodegeneration or damage to the brain and spinal cord. However, since the abundance of miRNAs in CSF is low, their isolation and detection is technically difficult. In this review, we evaluate the findings of recent studies of CSF miRNAs as biomarkers of spinal cord injury (SCI) and neurodegenerative diseases. We also summarize the current knowledge concerning the methods of studying miRNA in CSF, including RNA isolation and normalization of the data, highlighting the caveats of these approaches and possible solutions.

MiR-873-5p: A Potential Molecular Marker for Cancer Diagnosis and Prognosis

miR-873 is a microRNA located on chromosome 9p21.1. miR-873-5p and miR-873-3p are the two main members of the miR-873 family. Most studies focus on miR-873-5p, and there are a few studies on miR-873-3p. The expression level of miR-873-5p was down-regulated in 14 cancers and up-regulated in 4 cancers. miR-873-5p has many targeted genes, which have unique molecular functions such as catalytic activity, transcription regulation, and binding. miR-873-5p affects cancer development through the PIK3/AKT/mTOR, Wnt/β-Catenin, NF-κβ, and MEK/ERK signaling pathways. In addition, the target genes of miR-873-5p are closely related to the proliferation, apoptosis, migration, invasion, cell cycle, cell stemness, and glycolysis of cancer cells. The target genes of miR-873-5p are also related to the efficacy of several anti-cancer drugs. Currently, in cancer, the expression of miR-873-5p is regulated by a variety of epigenetic factors. This review summarizes the role and mechanism of miR-873-5p in human tumors shows the potential value of miR-873-5p as a molecular marker for cancer diagnosis and prognosis.

Exploratory Profiling of Extracellular MicroRNAs in Cerebrospinal Fluid Comparing Leptomeningeal Metastasis with Other Central Nervous System Tumor Statuses

The diagnosis of leptomeningeal metastasis (LM) is often difficult due to the paucity of cancer cells in cerebrospinal fluid (CSF) and nonspecific findings on neuroimaging. Investigations of extracellular microRNAs (miRNAs) in CSF could be used for both the diagnosis and study of LM pathogenesis because they reflect the activity of disseminating cancer cells. We isolated CSF extracellular miRNAs from patients (n = 65) of different central nervous system tumor statuses, including cancer control, healthy control, LM, brain metastasis (BM), and primary brain tumor (BT) groups, and performed miRNA microarrays. In unsupervised clustering analyses, all LM and two BM samples showed unique profiles. Among 30 miRNAs identified for LM-specific biomarkers via a Prediction Analysis of Microarrays, miR-335-5p and miR-34b-3p were confirmed in both the discovery and validation samples (n = 23). Next, we performed a significance analysis of the microarray (SAM) to extract discriminative miRNA profiles of two selected CSF groups, with LM samples revealing a greater number of discriminative miRNAs than BM and BT samples compared to controls. Using SAM comparisons between LM and BM samples, we identified 30 upregulated and 6 downregulated LM miRNAs. To reduce bias from different primary cancers, we performed a subset analysis with primary non-small cell lung cancer, and 12 of 13 upregulated miRNAs in LM vs. BM belonged to the upregulated miRNAs in LM. We identified possible target genes and their biological processes that could be affected by LM discriminative miRNAs in NSCLC using the gene ontology database. In conclusion, we identified a unique extracellular miRNA profile in LM CSF that was different from BM, suggesting the use of miRNAs as LM biomarkers in studies of LM pathogenesis.

Prognostic and Predictive Biomarkers in Gliomas

Gliomas are the most common central nervous system tumors. New technologies, including genetic research and advanced statistical methods, revolutionize the therapeutic approach to the patient and reveal new points of treatment options. Moreover, the 2021 World Health Organization Classification of Tumors of the Central Nervous System has fundamentally changed the classification of gliomas and incorporated many molecular biomarkers. Given the rapid progress in neuro-oncology, here we compile the latest research on prognostic and predictive biomarkers in gliomas. In adult patients, IDH mutations are positive prognostic markers and have the greatest prognostic significance. However, CDKN2A deletion, in IDH-mutant astrocytomas, is a marker of the highest malignancy grade. Moreover, the presence of TERT promoter mutations, EGFR alterations, or a combination of chromosome 7 gain and 10 loss upgrade IDH-wildtype astrocytoma to glioblastoma. In pediatric patients, H3F3A alterations are the most important markers which predict the worse outcome. MGMT promoter methylation has the greatest clinical significance in predicting responses to temozolomide (TMZ). Conversely, mismatch repair defects cause hypermutation phenotype predicting poor response to TMZ. Finally, we discussed liquid biopsies, which are promising diagnostic, prognostic, and predictive techniques, but further work is needed to implement these novel technologies in clinical practice.

Downregulation of CSF-derived miRNAs miR-142-3p and miR-17-5p may be associated with post-dural puncture headache in pregnant women upon spinal anaesthesia

Background

Postdural puncture headache (PDPH) develops due to puncture of the dura mater. The risk factors that influence PDPH incidence are Body Mass Index (BMI), sex, spinal needle type, history of headache, and loss of Cerebrospinal fluid (CSF) volume, yet there is no consensus on these risk factors. The pathophysiology of PDPH is poorly understood. The molecular pathways that may lead to PDPH are unknown. In this study, CSF – derived microRNAs (miRNAs) were investigated for their potential to predispose to PDPH in a population of pregnant women.

Methods

Pregnant women going under cesarean section via spinal anesthesia were included in the study with the criteria of the subjects presenting American Society of Anesthesiologists (ASA) physical status I. Patients were classified into two groups as with PDPH (n = 10) and without PDPH (n = 12) based on International Headache Society’s PDPH definition. CSF-derived microRNAs were investigated for their differential expression levels in PDPH patients compared with the healthy controls using microfluidic gene expression platform.

Results

Out of seventy-six miRNAs, two miRNAs, namely miR-142-3p and miR-17-5p, were significantly downregulated in PDPH patients (Mann-Whitney U test, p < 0,05). BMI and age did not influence PDPH occurrence. The mean visual analogue scale (VAS) of the PDPH patients was 6,8 out of 10.

Conclusion

We have shown that downregulation of miR-142-3p and miR-17-5p may predispose pregnant women to PDPH upon spinal anesthesia. However, which genes are targeted by miR-142-3p and miR-17-5p-mediated effect on PDPH remains to be elucidated.

Description of a CSF-Enriched miRNA Panel for the Study of Neurological Diseases

Background: The study of circulating miRNAs in CSF has gained tremendous attention during the last years, as these molecules might be promising candidates to be used as biomarkers and provide new insights into the disease pathology of neurological disorders. Objective: The main aim of this study was to describe an OpenArray panel of CSF-enriched miRNAs to offer a suitable tool to identify and characterize new molecular signatures in different neurological diseases. Methods: Two hundred and fifteen human miRNAs were selected to be included in the panel, and their expression and abundance in CSF samples were analyzed. In addition, their stability was studied in order to propose suitable endogenous controls for CSF miRNA studies. Results: miR-143-3p and miR-23a-3p were detected in all CSF samples, while another 80 miRNAs were detected in at least 70% of samples. miR-770-5p was the most abundant miRNA in CSF, presenting the lowest mean Cq value. In addition, miR-26b-5p, miR-335-5p and miR-92b-3p were the most stable miRNAs and could be suitable endogenous normalizers for CSF miRNA studies. Conclusions: These OpenArray plates might be a suitable and efficient tool to identify and characterize new molecular signatures in different neurological diseases and would improve the yield of miRNA detection in CSF.

Positron emission tomography and magnetic resonance imaging in primary central nervous system lymphoma-a narrative review

This review addresses the challenges of primary central nervous system (CNS) lymphoma diagnosis, assessment of treatment response, and detection of recurrence. Primary CNS lymphoma is a rare form of extra-nodal non-Hodgkin lymphoma that can involve brain, spinal cord, leptomeninges, and eyes. Primary CNS lymphoma lesions are most commonly confined to the white matter or deep cerebral structures such as basal ganglia and deep periventricular regions. Contrast-enhanced magnetic resonance imaging (MRI) is the standard diagnostic modality employed by neuro-oncologists. MRI often shows common morphological features such as a single or multiple uniformly well-enhancing lesions without necrosis but with moderate surrounding edema. Other brain tumors or inflammatory processes can show similar radiological patterns, making differential diagnosis difficult. [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) has selected utility in cerebral lymphoma, especially in diagnosis. Primary CNS lymphoma can sometimes present with atypical findings on MRI and FDG PET, such as disseminated disease, non-enhancing or ring-like enhancing lesions. The complementary strengths of PET and MRI have led to the development of combined PET-MR systems, which in some cases may improve lesion characterization and detection. By highlighting active developments in this field, including advanced MRI sequences, novel radiotracers, and potential imaging biomarkers, we aim to spur interest in sophisticated imaging approaches.

Dichotomy in Growth and Invasion from Low- to High-Grade Glioma Cellular Variants

Glial dysfunction outraging CNS plasticity and integrity results in one of the most dangerous cancers, namely glioma, featuring little median survival period and high recurrence. The hallmark properties of proliferation, invasion and angiogenesis with the infiltrated macrophages in glioma are expected to be tightly coupled or cross-linked, but not properly related so far. The present study is aimed to find a relationship between this featured quadrangle from lower to higher grades (HG) of post-operative glioma tissues and their invading subsets. Elevated Ki67-associated proliferation in lower grades (LG) was supported with VEGF dependent angiogenic maintenance which found a decrease unlikely in HG. In contrast, MMP 2 and 9-associated invasions augmented high in HG with the dominant presence of CD204⁺ M2 polarized macrophages and a general increase in global DNMT1-associated methylation. Marked differences found in ECM invading cellular subsets of HG showing high proliferative capacity indicating rationally for recurrence, contrasting the nature of gross tumor tissue of the same grade. Thus in LG, the neoplastic lesion is more inclined to its growth while in higher grade more disposed towards tissue wreckage in support with cellular environmental milieu whereas the cellular variants and subsets of invaded cells showed different trends. Therefore, some operational dichotomy or coupling among cellular variants in glioma is active in determining its low- to high-grade transition and aggressive progression.

Liquid Biomarkers for Improved Diagnosis and Classification of CNS Tumors

Liquid biopsy, as a non-invasive technique for cancer diagnosis, has emerged as a major step forward in conquering tumors. Current practice in diagnosis of central nervous system (CNS) tumors involves invasive acquisition of tumor biopsy upon detection of tumor on neuroimaging. Liquid biopsy enables non-invasive, rapid, precise and, in particular, real-time cancer detection, prognosis and treatment monitoring, especially for CNS tumors. This approach can also uncover the heterogeneity of these tumors and will likely replace tissue biopsy in the future. Key components of liquid biopsy mainly include circulating tumor cells (CTC), circulating tumor nucleic acids (ctDNA, miRNA) and exosomes and samples can be obtained from the cerebrospinal fluid, plasma and serum of patients with CNS malignancies. This review covers current progress in application of liquid biopsies for diagnosis and monitoring of CNS malignancies.

Emerging insights into origin and pathobiology of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is an aggressive cancer typically confined to the brain, eyes, leptomeninges and spinal cord, without evidence of systemic involvement. PCNSL remains a challenge for scientists and clinicians due to insufficient biological knowledge, a lack of appropriate animal models and validated diagnostic biomarkers. We summarize recent findings on genomic, transcriptomic and epigenetic alterations identified in PCNSL. These findings help to define pathobiology of the disease and delineate defects in B cell differentiation. Evidence from genomic and transcriptomic studies helps to separate PCNSL from other hematological malignancies, improves diagnostics and reveals new therapeutic targets for treatment. Discovery of the CNS lymphatic system may be instrumental in better understanding the origin of the disease. We critically assess the attempts to model PCNSL in rodents, and conclude that there is a lack of a genetic/transgenic model that adequately mimics pathogenesis of the disease. Contribution of the tumor microenvironment in tumorigenesis and aggressiveness of PCNSL remains understudied. Assessing heterogeneity of immune infiltrates, cytokine profiling and molecular markers, may improve diagnostics and put forward new therapeutic strategies.

miRNA-21 may serve as a promising noninvasive marker of glioma with a high diagnostic performance: a pooled analysis of 997 patients

Background:

Although various serum and tissue biomarkers have been investigated for glioma diagnosis, no gold standard has been identified. miRNA-21 was demonstrated to be a promising biomarker for the diagnosis of various brain tumors, whereas there remains uncertainty concerning whether miRNA-21 could be used as a good clinical diagnostic biomarker for glioma. The current meta-analysis aimed to evaluate the diagnostic accuracy of miRNA-21 as a potent biomarker in adults with suspected glioma.

Methods:

The Pubmed and Embase databases were searched systematically from inception to January 2020 to identify relevant research reports. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. Summary receiver operating characteristic (SROC) curves were used to evaluate the overall diagnostic performance. Meta-regression and subgroup analyses were conducted to determine the source of heterogeneity and test the robustness of the results.

Results:

From 5394 citations with 997 subjects that met the inclusion criteria, 11 studies were selected. Summary estimates of the diagnostic performance of miRNA-21 were as follows: sensitivity, 0.83 [95% confidence interval (CI): 0.73–0.89]; specificity, 0.92 (95% CI: 0.85–0.96); PLR, 10.20 (95% CI: 5.10–20.30); NLR, 0.19 (95% CI: 0.12–0.31); and DOR, 54 (95% CI: 19–155). The area under the SROC curve was 0.94 (95% CI: 0.92–0.96). Deeks’s funnel plot revealed no evidence of publication bias (p = 0.59). Meta-regression analysis suggested that study publication year could attribute to the heterogeneity. Subgroup analysis found miRNA-21 had a constant high diagnostic accuracy across different ethnicity, glioma grade, sample source, and study region.

Conclusion:

This meta-analysis demonstrated that miRNA-21 has high diagnostic performance and could serve as a promising noninvasive diagnostic marker for glioma. Further large prospective studies are needed to validate its diagnostic value and its prognostic significance and therapeutic effects.

Time to focus on circulating nucleic acids for diagnosis and monitoring of gliomas: A systematic review of their role as biomarkers

Gliomas are diffusely growing tumours arising from progenitors within the central nervous system. They encompass a range of different molecular types and subtypes, many of which have a well-defined profile of driver mutations, copy number changes and DNA methylation patterns. A majority of gliomas will require surgical intervention to relieve raised intracranial pressure and reduce tumour burden. A proportion of tumours, however, are located in neurologically sensitive areas and a biopsy poses a significant risk of a deficit. A majority of gliomas recur after surgery, and monitoring tumour burden of the recurrence is currently achieved by imaging. However, most imaging modalities have limitations in assessing tumour burden and infiltration into adjacent brain, and sometimes imaging is unable to discriminate between tumour recurrence and pseudo-progression. Liquid biopsies, obtained from body fluids such as cerebrospinal fluid or blood, contain circulating nucleic acids or extracellular vesicles containing tumour-derived components. The studies for this systematic review were selected according to PRISMA criteria, and suggest that the detection of circulating tumour-derived nucleic acids holds great promises as biomarker to aid diagnosis and prognostication by monitoring tumour progression, and thus can be considered a pathway towards personalized medicine.

Extracellular vesicles derived from hypoxic glioma stem-like cells confer temozolomide resistance on glioblastoma by delivering miR-30b-3p

Rationale: Glioma stem-like cells (GSCs) contribute to temozolomide (TMZ) resistance in gliomas, although the mechanisms have not been delineated. Methods: In vitro functional experiments (colony formation assay, flow cytometric analysis, TUNEL assay) were used to assess the ability of extracellular vesicles (EVs) from hypoxic GSCs to promote TMZ resistance in glioblastoma (GBM) cells. RNA sequencing and quantitative Reverse Transcription-PCR were employed to identify the functional miRNA in hypoxic EVs. Chromatin immunoprecipitation assays were performed to analyze the transcriptional regulation of miRNAs by HIF1α and STAT3. RIP and RNA pull-down assays were used to validate the hnRNPA2B1-mediated packaging of miRNA into EVs. The function of EV miR-30b-3p from hypoxic GSCs was verified by in vivo experiments and analysis of clinical samples. Results: Hypoxic GSC-derived EVs exerted a greater effect on GBM chemoresistance than those from normoxic GSCs. The miRNA profiling revealed that miR-30b-3p was significantly upregulated in the EVs from hypoxic GSCs. Further, HIF1α and STAT3 transcriptionally induced miR-30b-3p expression. RNA immunoprecipitation and RNA-pull down assays revealed that binding of miR-30b-3p with hnRNPA2B1 facilitated its transfer into EVs. EV-packaged miR-30b-3p (EV-miR-30b-3p) directly targeted RHOB, resulting in decreased apoptosis and increased proliferation in vitro and in vivo. Our results provided evidence that miR-30b-3p in CSF could be a potential biomarker predicting resistance to TMZ. Conclusion: Our findings indicated that targeting EV-miR-30b-3p could provide a potential treatment strategy for GBM.

Clinical significance of interleukin-10 concentration in the cerebrospinal fluid of patients with primary central nervous system lymphoma

The diagnostic and prognostic evaluation of primary central nervous system lymphoma (PCNSL) is challenging due to the lack of sensitive biomarkers. The present study aimed to evaluate the value of interleukin (IL)-10 in this context. Between October 2016 and December 2018, 91 patients with suspected intracranial neoplasms were recruited, and the concentrations of IL-10 or IL-6 in both the cerebrospinal fluid (CSF) and blood were measured and analyzed by the Kruskal-Wallis test. The correlation between CSF IL-6 or IL-10 levels and tumor size was determined by Spearman's coefficient analysis. The receiver operating characteristic curve was used to evaluate the diagnostic value of CSF IL-6 and IL-10 levels. Median progression-free survival (PFS) and overall survival time were calculated using Kaplan-Meier survival analysis. Among the 91 patients, 3 were diagnosed with PCNSL on the basis of neuroimaging data and CSF IL-10 levels. A total of 35 cases were verified to show diffuse large B-cell lymphoma on histological assessment, 17 of which were diagnosed as PCNSL by MRI. The median PFS and OS were 8.00 months [95% confidence interval (CI), 3.94-12.06) and 17.5 months (95% CI, 11.55-23.45) respectively in the 12 PNCSL cases with regular follow up. The diagnostic efficiency of serum IL-6 levels was lower than that of serum IL-10 levels (P=0.030), which, in turn, was lower than that of CSF IL-10 levels (P<0.001). The decline and increase in CSF IL-10 levels was concurrent with improvement and deterioration in manifestation, respectively, which predated the MRI variation. High CSF IL-10 levels indicated low Karnofsky performance scale scores and shortened PFS times. CSF IL-10 levels higher than 1,000 pg/ml signified disease progression. CSF IL-10 levels could be a sensitive biomarker guiding the differential diagnosis, early recurrence detection, prognostic evaluation and therapeutic strategy establishment in cases of PCNSL.

Liquid biopsy in central nervous system tumors: the potential roles of circulating miRNA and exosomes

The Central nervous system (CNS) tumor still remains the most lethal cancer, and It is hard to diagnose at an earlier stage on most occasions. It is found that recurrent disease is finally observed in patients who occurred chemo-resistance after completely primary treatment. It is a challenge that monitoring treatment efficacy and tumor recurrence of CNS tumors are full of risks and difficulties by brain biopsies. However, the brain biopsies are considered as an invasive technique with low specificity and low sensitivity. In contrast, the liquid biopsy is based on blood and cerebrospinal fluid (CSF) test, which is going to acceptable among the patients through it's minimally invasive and serial bodily fluids. The advantages of liquid biopsy are to follow the development of tumors, provide new insights in real time, and accurate medical care. The major analytical constituents of liquid biopsy contain the Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), circulating cell-free microRNAs (cfmiRNAs), and circulating exosomes. Liquid biopsy has been widely utilized in CNS tumors in recent years, and the CTCs and ctDNA have become the hot topics for researching. In this review, we are going to explain the clinical potential of liquid biopsy biomarkers in CNS tumor by testing circulating miRNAs and exosomes to evaluate diagnose, prognosis, and response to treatment.

The role of MiRNA-21 in gliomas: Hope for a novel therapeutic intervention?

Gliomas are the most common primary brain tumors in adults. They are generally very resistant to treatment and are therefore associated with negative outcomes. MicroRNAs (miRNAs) are small, non-coding RNA molecules that affect many cellular processes by regulating gene expression and, post-transcriptionally, the translation of mRNAs. MiRNA-21 has been consistently shown to be upregulated in glioma and research has shown that it is involved in a wide variety of biological pathways, promoting tumor cell survival and invasiveness. Furthermore, it has been implicated in resistance to treatment, both against chemotherapy and radiotherapy. In this review, we gathered the existent data on miRNA-21 and gliomas, in terms of its expression levels, association with grade and prognosis, the pathways it involves and its targets in glioma, and finally how it leads to treatment resistance. Furthermore, we discuss how this knowledge could be applied in clinical practice in the years to come. To our knowledge, this is the first review to assess in extent and depth the role of miRNA-21 in gliomas.

High-Throughput Sequencing-Based Identification of Serum Exosomal Differential miRNAs in High-Grade Glioma and Intracranial Lymphoma

Objective

At present, no effective noninvasive method is currently available for the differential diagnosis of high-grade glioma and intracranial lymphoma. In the present study, we aimed to screen microRNA (miRNA) markers in serum exosomes for differential diagnosis of high-grade glioma and intracranial lymphoma using high-throughput sequencing technology.

Methods

Patients with intracranial lymphoma or high-grade glioma and healthy controls were included in this study (training cohort (n = 10) and validation cohort: intracranial lymphoma (n = 10), high-grade glioma (n = 32), and healthy controls (n = 20)). After RNA was extracted from serum exosomes, the high-throughput sequencing was used to determine the expression profiles of serum exosomal miRNAs and screen the differentially expressed miRNAs. RT-qPCR was used to verify the expressions of the selected miRNAs. The differences of miRNA expressions between groups were assessed by the Kruskal-Wallis test. The diagnostic value was analyzed using the receiver operating characteristic (ROC) curve.

Results

High-throughput sequencing demonstrated that 170 miRNAs, including 109 upregulated ones and 61 downregulated ones, were differentially expressed in serum exosomes between the patients with intracranial lymphoma and high-grade glioma. Compared with the healthy controls, the number of differential serum exosomal miRNAs in the high-grade glioma group and intracranial lymphoma group was 130 and 173, respectively. RT-qPCR proved that both miR-766-5p and miR-376b-5p were significantly downregulated in high-grade glioma and intracranial lymphoma patients compared with the healthy controls (all p < 0.001), and the expression of serum exosomal miR-766-5p in the intracranial lymphoma group was lower compared with the high-grade glioma group (p < 0.05). The areas under ROC curve (AUCs) of serum exosomal miR-766-5p and miR-376b-5p for the diagnosis of glioma were 0.8883 (p < 0.001) and 0.7688 (p = 0.001), respectively, and they were 0.9271 (p < 0.001) and 0.8542 (p < 0.001), respectively, for the diagnosis of intracranial lymphoma. Moreover, the AUC value of serum exosomal miR-766-5p for the differential diagnosis of glioma and intracranial lymphoma was 0.7201 (p = 0.026).

Conclusions

miR-766-5p and miR-376b-5p in serum exosomes might be used as auxiliary diagnostic indicators for high-grade glioma and intracranial lymphoma, and miR-766-5p might be used as a differential diagnostic marker for both diseases.

Augenbefall und Systemerkrankung – periokuläre und intraokuläre Lymphome

Hintergrund

Das okuläre Lymphom wird anhand seiner anatomischen Lokalisation in die intraokulären und periokulären Lymphome eingeteilt. Intraokulär kann die Uvea mit ihren Strukturen betroffen sein oder die Retina in Verbindung mit dem Glaskörper. Die periokulären Lymphome treten in Orbita, Bindehaut, Tränenapparat oder Lid auf. Von großer Bedeutung ist die Unterscheidung zwischen primären Lymphomen der Region oder systemischem Befall. Über die letzten Jahrzehnte konnte in den westlichen Ländern eine konstant steigende Inzidenz okulärer Lymphome nachgewiesen werden.

Ziel

Dieser Beitrag soll einen Überblick über die vielfältigen Manifestationen, Diagnostik, Therapie sowie Prognose und Nachsorge geben.

Material und Methoden

Der Beitrag basiert auf einer selektiven Literaturrecherche über die MEDLINE-Datenbank zum Thema okuläre Lymphome sowie den persönlichen Erfahrungen der Autoren.

Ergebnisse

Je nach Lokalisation können die Symptome sehr unterschiedlich sein. Die Diagnose erfolgt über eine Probebiopsie und anschließende zytologische/histologische und ggf. molekularpathologische Untersuchung. Strahlentherapeutische sowie systemische Verfahren stellen die am häufigsten angewendeten Therapieverfahren dar. Die Prognose hängt sehr stark von der Lokalisation, dem Subtyp des Lymphoms sowie dem Ausmaß des Tumorbefalls ab.

Diskussion

Das okuläre Lymphom berührt in Diagnostik, Therapie und Nachsorge die Schnittstellen zwischen Ophthalmologie, (Hämato‑)Onkologie, Strahlentherapie, Neurologie, Neurochirurgie, Mund-Kiefer-Gesichts-Chirurgie, Hals-Nasen-Ohren-Heilkunde, Dermatologie, Radiologie, Pathologie und Psychoonkologie. Dabei spielt der Augenarzt als Eingangsarzt bei dieser Systemerkrankung eine wesentliche Rolle.

Brain Tumor-Derived Extracellular Vesicles as Carriers of Disease Markers: Molecular Chaperones and MicroRNAs

Primary and metastatic brain tumors are usually serious conditions with poor prognosis, which reveal the urgent need of developing rapid diagnostic tools and efficacious treatments. To achieve these objectives, progress must be made in the understanding of brain tumor biology, for example, how they resist natural defenses and therapeutic intervention. One resistance mechanism involves extracellular vesicles that are released by tumors to meet target cells nearby or distant via circulation and reprogram them by introducing their cargo. This consists of different molecules among which are microRNAs (miRNAs) and molecular chaperones, the focus of this article. miRNAs modify target cells in the immune system to avoid antitumor reaction and chaperones are key survival molecules for the tumor cell. Extracellular vesicles cargo reflects the composition and metabolism of the original tumor cell; therefore, it is a source of markers, including the miRNAs and chaperones discussed in this article, with potential diagnostic and prognostic value. This and their relatively easy availability by minimally invasive procedures (e.g., drawing venous blood) illustrate the potential of extracellular vesicles as useful materials to manage brain tumor patients. Furthermore, understanding extracellular vesicles circulation and interaction with target cells will provide the basis for using this vesicle for delivering therapeutic compounds to selected tumor cells.

The potential of cerebrospinal fluid-based liquid biopsy approaches in CNS tumors

Cerebrospinal fluid (CSF) may be the best hope for minimally invasive diagnosis and treatment monitoring of central nervous system (CNS) malignancies. Discovery/validation of cell-free nucleic acid and protein biomarkers has the potential to revolutionize CNS cancer care, paving the way for presurgical evaluation, earlier detection of recurrence, and the selection of targeted therapies. While detection of mutations, changes in RNA and miRNA expression, epigenetic alterations, and elevations of protein levels have been detected in the CSF of patients with CNS tumors, most of these biomarkers remain unvalidated. In this review, we focus on the molecular changes that have been identified in a variety of CNS tumors and profile the approaches used to detect these alterations in clinical samples. We further emphasize the importance of systemic collection of CSF and the establishment of standardized collection protocols that will lead to better cross-study biomarker validation and hopefully FDA-approved clinical markers.

Circulating Cell-Free Nucleic Acids as Epigenetic Biomarkers in Precision Medicine

The circulating cell-free nucleic acids (ccfNAs) are a mixture of single- or double-stranded nucleic acids, released into the blood plasma/serum by different tissues via apoptosis, necrosis, and secretions. Under healthy conditions, ccfNAs originate from the hematopoietic system, whereas under various clinical scenarios, the concomitant tissues release ccfNAs into the bloodstream. These ccfNAs include DNA, RNA, microRNA (miRNA), long non-coding RNA (lncRNA), fetal DNA/RNA, and mitochondrial DNA/RNA, and act as potential biomarkers in various clinical conditions. These are associated with different epigenetic modifications, which show disease-related variations and so finding their role as epigenetic biomarkers in clinical settings. This field has recently emerged as the latest advance in precision medicine because of its clinical relevance in diagnostic, prognostic, and predictive values. DNA methylation detected in ccfDNA has been widely used in personalized clinical diagnosis; furthermore, there is also the emerging role of ccfRNAs like miRNA and lncRNA as epigenetic biomarkers. This review focuses on the novel approaches for exploring ccfNAs as epigenetic biomarkers in personalized clinical diagnosis and prognosis, their potential as therapeutic targets and disease progression monitors, and reveals the tremendous potential that epigenetic biomarkers present to improve precision medicine. We explore the latest techniques for both quantitative and qualitative detection of epigenetic modifications in ccfNAs. The data on epigenetic modifications on ccfNAs are complex and often milieu-specific posing challenges for its understanding. Artificial intelligence and deep networks are the novel approaches for decoding complex data and providing insight into the decision-making in precision medicine.