Genetic/molecular alterations of meningiomas and the signaling pathways targeted

Paired Primary and Recurrent Rhabdoid Meningiomas: Cytogenetic Alterations, BAP1 Gene Expression Profile and Patient Outcome

Rhabdoid meningiomas (RM) are a rare meningioma subtype with a heterogeneous clinical course which is more frequently associated with recurrence, even among tumors undergoing-complete surgical removal. Here, we retrospectively analyzed the clinical-histopathological and cytogenetic features of 29 tumors, from patients with recurrent (seven primary and 14 recurrent tumors) vs. non-recurrent RM (n = 8). Recurrent RM showed one (29%), two (29%) or three (42%) recurrences. BAP1 loss of expression was found in one third of all RM at diagnosis and increased to 100% in subsequent tumor recurrences. Despite both recurrent and non-recurrent RM shared chromosome 22 losses, non-recurrent tumors more frequently displayed extensive losses of chromosome 19p (62%) and/or 19q (50%), together with gains of chromosomes 20 and 21 (38%, respectively), whereas recurrent RM (at diagnosis) displayed more complex genotypic profiles with extensive losses of chromosomes 1p, 14q, 18p, 18q (67% each) and 21p (50%), together with focal gains at chromosome 17q22 (67%). Compared to paired primary tumors, recurrent RM samples revealed additional losses at chromosomes 16q and 19p (50% each), together with gains at chromosomes 1q and 17q in most recurrent tumors (67%, each). All deceased recurrent RM patients corresponded to women with chromosome 17q gains, although no statistical significant differences were found vs. the other RM patients.

Malignant perineurioma derived from the retroperitoneum with an aggressive clinical course: a case report

BACKGROUND

Malignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature.

CASE PRESENTATION

The patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery.

CONCLUSIONS

This rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.

Related mechanisms, current treatments, and new perspectives in meningioma

Meningiomas are non-glial tumors that are the most common primary brain tumors in adults. Although meningioma can possibly be cured with surgical excision, variations in atypical/anaplastic meningioma have a high recurrence rate and a poor prognosis. As a result, it is critical to develop novel therapeutic options for high-grade meningiomas. This review highlights the current histology of meningiomas, prevalent genetic and molecular changes, and the most extensively researched signaling pathways and therapies in meningiomas. It also reviews current clinical studies and novel meningioma treatments, including immunotherapy, microRNAs, cancer stem cell methods, and targeted interventions within the glycolysis pathway. Through the examination of the complex landscape of meningioma biology and the highlighting of promising therapeutic pathways, this review opens the way for future research efforts aimed at improving patient outcomes in this prevalent intracranial tumor entity.

The Evolving Classification of Meningiomas: Integration of Molecular Discoveries to Inform Patient Care

Meningioma classification and treatment have evolved over the past eight decades. Since Bailey, Cushing, and Eisenhart's description of meningiomas in the 1920s and 1930s, there have been continual advances in clinical stratification by histopathology, radiography and, most recently, molecular profiling, to improve prognostication and predict response to therapy. Precise and accurate classification is essential to optimizing management for patients with meningioma, which involves surveillance imaging, surgery, primary or adjuvant radiotherapy, and consideration for clinical trials. Currently, the World Health Organization (WHO) grade, extent of resection (EOR), and patient characteristics are used to guide management. While these have demonstrated reliability, a substantial number of seemingly benign lesions recur, suggesting opportunities for improvement of risk stratification. Furthermore, the role of adjuvant radiotherapy for grade 1 and 2 meningioma remains controversial. Over the last decade, numerous studies investigating the molecular drivers of clinical aggressiveness have been reported, with the identification of molecular markers that carry clinical implications as well as biomarkers of radiotherapy response. Here, we review the historical context of current practices, highlight recent molecular discoveries, and discuss the challenges of translating these findings into clinical practice.

Correlation of Molecular Status with Preoperative Olfactory Function in Olfactory Groove Meningioma

PURPOSE

The study aims to examine the possible correlation between genomic alterations and preoperative olfactory function in patients with olfactory groove meningioma (OGM), due to the frequent presence of olfactory impairment.

METHODS

We utilised next-generation sequencing to analyse samples from 22 individuals with OGM in order to detect driver mutations. Tumour morphology was assessed using preoperative imaging, whereas olfactory function was examined using Sniffin' Sticks.

RESULTS

In a study of 22 OGM patients, mutations were as follows: 10 with SMO/SUFU, 7 with AKT1, and 5 as wild type. Planum sphenoidale hyperostosis (PSH) was present in 75% of patients, showing significant variation by mutation (p = 0.048). Tumour volumes, averaging 25 cm3, significantly differed among groups. PSH negatively impacted olfaction, notably affecting odour threshold, discrimination, identification, and global olfactory performance score (TDI) (p values ranging from <0.001 to 0.003). Perifocal oedema was associated with lower TDI (p = 0.009) and altered threshold scores (p = 0.038). Age over 65 and female gender were linked to lower thresholds and discrimination scores (p = 0.037 and p = 0.019).

CONCLUSION

The study highlights PSH and perifocal oedema's significant effect on olfactory function in OGM patients but finds no link between olfactory impairment and tumour mutations, possibly due to the small sample size. This suggests that age and gender affect olfactory impairment. Additional research with a larger group of participants is needed to explore the impact of OGM driver mutations on olfactory performance.

Radiotherapy intensification for atypical and malignant meningiomas: A systematic review

Background

The outcomes of nonbenign (WHO Grades 2 and 3 [G2, G3]) meningiomas are suboptimal and radiotherapy (RT) dose intensification strategies have been investigated. The purpose of this review is to report on clinical practice and outcomes with particular attention to RT doses and techniques.

Methods

The PICO criteria (Population, Intervention, Comparison, and Outcomes) were used to frame the research question, directed at outlining the clinical outcomes in patients with G2-3 meningiomas treated with RT. The same search strategy was run in Embase and MEDLINE and, after deduplication, returned 1 807 records. These were manually screened for relevance and 25 were included.

Results

Tumor outcomes and toxicities are not uniformly reported in the selected studies since different endpoints and time points have been used by different authors. Many risk factors for worse outcomes are described, the most common being suboptimal RT. This includes no or delayed RT, low doses, and older techniques. A positive association between RT dose and progression-free survival (PFS) has been highlighted by analyzing the studies in this review (10/25) that report the same endpoint (5y-PFS).

Conclusions

This literature review has shown that standard practice RT leads to suboptimal tumor control rates in G2-3 meningiomas, with a significant proportion of disease recurring after a relatively short follow-up. Randomized controlled trials are needed in this setting to define the optimal RT approach. Given the increasing data to suggest a benefit of higher RT doses for high-risk meningiomas, novel RT technologies with highly conformal dose distributions are preferential to achieve optimal target coverage and organs at risk sparing.

Noncoding RNA landscape and their emerging roles as biomarkers and therapeutic targets in meningioma

Meningiomas are among the most prevalent primary CNS tumors in adults, accounting for nearly 38% of all brain neoplasms. The World Health Organization (WHO) grade assigned to meningiomas guides medical care in patients and is primarily based on tumor histology and malignancy potential. Although often considered benign, meningiomas with complicated histology, limited accessibility for surgical resection, and/or higher malignancy potential (WHO grade 2 and WHO grade 3) are harder to combat, resulting in significant morbidity. With limited treatment options and no systemic therapies, it is imperative to understand meningioma tumorigenesis at the molecular level and identify novel therapeutic targets. The last decade witnessed considerable progress in understanding the noncoding RNA landscape of meningioma, with microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) emerging as molecular entities of interest. This review aims to highlight the commonly dysregulated miRNAs and lncRNAs in meningioma and their correlation with meningioma progression, malignancy, recurrence, and radioresistance. The role of "key" miRNAs as biomarkers and their therapeutic potential has also been reviewed in detail. Furthermore, current and emerging therapeutic modalities for meningioma have been discussed, with emphasis on the need to identify and subsequently employ clinically relevant miRNAs and lncRNAs as novel therapeutic targets and biomarkers.

Drug target therapy and emerging clinical relevance of exosomes in meningeal tumors

Meningioma is the most common central nervous system (CNS) tumor. In recent decades, several efforts have been made to eradicate this disease. Surgery and radiotherapy remain the standard treatment options for these tumors. Drug therapy comes to play its role when both surgery and radiotherapy fail to treat the tumor. This mostly happens when the tumors are close to vital brain structures and are nonbenign. Although a wide variety of chemotherapeutic drugs and molecular targeted drugs such as tyrosine kinase inhibitors, alkylating agents, endocrine drugs, interferon, and targeted molecular pathway inhibitors have been studied, the roles of numerous drugs remain unexplored. Recent interest is growing toward studying and engineering exosomes for the treatment of different types of cancer including meningioma. The latest studies have shown the involvement of exosomes in the theragnostic of various cancers such as the lung and pancreas in the form of biomarkers, drug delivery vehicles, and vaccines. Proper attention to this new emerging technology can be a boon in finding the consistent treatment of meningioma.

Brain Tumors: Development, Drug Resistance, and Sensitization - An Epigenetic Approach

In this article, we describe contrasting developmental aspects of paediatric and adult brain tumours. We hypothesize that the formation of cancer progenitor cells, for both paediatric and adult, could be due to epigenetic events. However, the progression of adult brain tumours selectively involves more mutations compared to paediatric tumours. We further discuss epigenetic switches, comprising both histone modifications and DNA methylation, and how they can differentially regulate transcription and expression of oncogenes and tumour suppressor genes. Next, we summarize the currently available therapies for both types of brain tumours, explaining the merits and failures leading to drug resistance. We analyse different mechanisms of drug resistance and the role of epigenetics in this process. We then provide a rationale for combination therapy, which includes epigenetic drugs. In the end, we postulate a concept which describes how a combination therapy could be initiated. The timing, doses, and order of individual drug regimens will depend on the individual case. This type of combination therapy will be part of a personalized medicine which will differ from patient to patient.

DNA methylation meningioma biomarkers: attributes and limitations

Meningioma, one of the most common primary central nervous system tumors, are classified into three grades by the World Health Organization (WHO) based on histopathology. The gold-standard treatment, surgical resection, is hampered by issues such as incomplete resection in some cases and a high recurrence rate. Alongside genetic alterations, DNA methylation, plays a crucial role in progression of meningiomas in the occurrence and development of meningiomas. The epigenetic landscape of meningioma is instrumental in refining tumor classification, identifying robust molecular markers, determining prognosis, guiding treatment selection, and innovating new therapeutic strategies. Existing classifications lack comprehensive accuracy, and effective therapies are limited. Methylated DNA markers, exhibiting differential characteristics across varying meningioma grades, serve as invaluable diagnostic tools. Particularly, combinatorial methylated markers offer insights into meningioma pathogenesis, tissue origin, subtype classification, and clinical outcomes. This review integrates current research to highlight some of the most promising DNA and promoter methylation markers employed in meningioma diagnostics. Despite their promise, the development and application of DNA methylation biomarkers for meningioma diagnosis and treatment are still in their infancy, with only a handful of DNA methylation inhibitors currently clinically employed for meningioma treatment. Future studies are essential to validate these markers and ascertain their clinical utility. Combinatorial methylated DNA markers for meningiomas have broad implications for understanding tumor development and progression, signaling a paradigm shift in therapeutic strategies for meningiomas.

Clinical, Histopathologic and Genetic Features of Rhabdoid Meningiomas

Rhabdoid meningiomas (RM) shows heterogeneous histological findings, and a wide variety of chromosomal copy number alterations (CNA) are associated with an unpredictable course of the disease. In this study, we analyzed a series of 305 RM samples from patients previously reported in the literature and 33 samples from 23 patients studied in our laboratory. Monosomy 22-involving the minimal but most common recurrent region loss of the 22q11.23 chromosomal region was the most observed chromosomal alteration, followed by losses of chromosomes 14, 1, 6, and 19, polysomies of chromosomes 17, 1q, and 20, and gains of 13q14.2, 10p13, and 21q21.2 chromosomal regions. Based on their CNA profile, RM could be classified into two genetic subgroups with distinct clinicopathologic features characterized by the presence of (1) chromosomal losses only and (2) combined losses and gains of several chromosomes. The latter displays a higher frequency of WHO grade 3 tumors and poorer clinical outcomes.

Identification of key genes of anti-programmed death ligand 1 for meningioma immunotherapy by bioinformatic analysis

Meningioma is one of the most common primary tumors in the central nervous system (CNS). A deeper understanding of its molecular characterization could provide potential therapeutic targets to reduce recurrence. In this study, we attempted to identify specific gene mutations in meningioma for immunotherapy. One GSE43290 dataset was obtained from the Gene Expression Omnibus (GEO) database to find differentially expressed genes (DEGs) between meningioma tissues and normal meninges. In total, 420 DEGs were identified, including 15 up-regulated and 405 down-regulated genes. Functional enrichment analysis showed that these DEGs were mainly enriched in PI3K-Akt signaling pathway, Focal adhesion, and MAPK signaling pathway. We identified 20 hub genes by protein-protein interaction (PPI) analysis. Among the hub genes, the expression of FLT1, CXCL8, JUN, THBS1, FECAM1, CD34, and FGF13 were negatively correlated with Programmed Death Ligand-1 (PD-L1). Additionally, the expression of those genes was co-regulated by miR-155-5p. The findings suggest that miR-155-5p play an important role in the pathogenesis of meningioma and may represent potential therapeutic targets for its anti-PD-L1 immunotherapy.

Whole-Exome Sequencing Reveals Recurrent but Heterogeneous Mutational Profiles in Sporadic WHO Grade 1 Meningiomas

Human WHO grade 1 meningiomas are generally considered benign tumors; despite this, they account for ≈50% of all recurrent meningiomas. Currently, limited data exist about the mutational profiles of grade 1 meningiomas and patient outcome. We investigated the genetic variants present in 32 WHO grade 1 meningiomas using whole exome sequencing, and correlated gene mutational profiles with tumor cytogenetics and patient outcome. Overall, WHO grade 1 meningiomas harbored numerous and heterogeneous genetic variants, which most frequently affected the NF2 (47%) gene and to a less extent the PNMA6A (22%), TIGD1 (16%), SMO (13%), PTEN (13%), CREG2 (9%), EEF1A1 (6%), POLR2A (6%), ARID1B (3%), and FAIM3 (3%) genes. Notably, non-synonymous genetic variants of SMO and POLR2A were restricted to diploid meningiomas, whereas NF2 mutations were only found among tumors that showed -22/22q^─ (with or without a complex karyotype). Based on NF2 mutations and tumor cytogenetics, four genetic profiles were defined with an impact on patient recurrence-free survival (RFS). These included (1) two good-prognosis tumor subgroups-diploid meningiomas (n=9) and isolated -22/22q^─ associated with NF2 mutation (n=7)-with RFS rates at 10 y of 100%; and (2) two subgroups of poor-prognosis meningiomas-isolated -22/22q^─ without NF2 mutation (n=3) and tumors with complex karyotypes (n=11)-with a RFS rate at 10 y of 48% (p=0.003). Our results point out the existence of recurrent but heterogeneous mutational profiles in WHO grade 1 meningiomas which have an impact on patient outcome.

EANO guideline on the diagnosis and management of meningiomas

Meningiomas are the most common intracranial tumors. Yet, only few controlled clinical trials have been conducted to guide clinical decision making, resulting in variations of management approaches across countries and centers. However, recent advances in molecular genetics and clinical trial results help to refine the diagnostic and therapeutic approach to meningioma. Accordingly, the European Association of Neuro-Oncology (EANO) updated its recommendations for the diagnosis and treatment of meningiomas. A provisional diagnosis of meningioma is typically made by neuroimaging, mostly magnetic resonance imaging. Such provisional diagnoses may be made incidentally. Accordingly, a significant proportion of meningiomas, notably in patients that are asymptomatic or elderly or both, may be managed by a watch-and-scan strategy. A surgical intervention with tissue, commonly with the goal of gross total resection, is required for the definitive diagnosis according to the WHO classification. A role for molecular profiling including gene panel sequencing and genomic methylation profiling is emerging. A gross total surgical resection including the involved dura is often curative. Inoperable or recurrent tumors requiring treatment can be treated with radiosurgery, if the size or the vicinity of critical structures allows that, or with fractionated radiotherapy (RT). Treatment concepts combining surgery and radiosurgery or fractionated RT are increasingly used, although there remain controversies regard timing, type, and dosing of the various RT approaches. Radionuclide therapy targeting somatostatin receptors is an experimental approach, as are all approaches of systemic pharmacotherapy. The best albeit modest results with pharmacotherapy have been obtained with bevacizumab or multikinase inhibitors targeting vascular endothelial growth factor receptor, but no standard of care systemic treatment has been yet defined.

Comprehensive overview of extracellular vesicle proteomics in meningioma: future strategy

Background

Meningioma arising from meninges is one among the various types of brain tumors. Others are, astrocytomas originating from astrocyte, oligodendrogliomas originating from oligodendrocyte, Ependymomas originating from ependymal cells and medulloblastomas originating from neurons. Current knowledge of molecular biology, genetics and epigenetics of meningioma is not sufficient. Therefore, In depth understanding of the mechanism of meningioma formation and progression is needed for its treatment and management. Grade I Grade I meningiomas are majorly classified as grade I, grade II and grade III. Meningioma can be indolent, slow growing or can be invasive and metastatic which can recurre. Grade I meningioma can be removed by surgery in comparison to invasive meningioma which may recurre with high propensity. This property of recurrence is responsible for high morbidity and mortality. Meningioma are majorly classified into three classes namely grade I, grade II, grade III. Protein biomarkers are considered as promising candidates for the diagnosis of meningioma.

Study

Various studies done on differential expression of proteins have shown increased expression of EGFR, NEK9, EPS812, CKAP4, SET and STAT2, in all the three grades of meningioma. Additionally, some proteins like HK2 are overexpressed in grade II and grade III meningioma than in grade I meningioma. Protein Markers, found on extracellular vesicles of different grades of meningioma can serve the same purpose. A test done on a sample of any kind of body fluid like blood, tear, saliva, urine etc. for recognizing the circulating cancer cells or DNA and extracellular vesicles released from them to help detecting the early stage of cancer is known as liquid biopsy. Solid biopsy has several limitations as compared to liquid biopsy. This is because the samples can be easily collected and studied in case of liquid biopsy. Exosomes are related with liquid biopsy and hence provide platform for better diagnosis, prognosis and treatment of any type of cancer including meningioma. Exosomal tetraspanin are important example of exosomal biomarkers. The tetraspanin network is a molecular scaffold which connects various proteins for signal transduction.

Conclusion

This study tells about the utility of proper knowledge of extracellular vesicle proteins and their profiles in different grades, which can help in better understanding of pathogenesis, diagnosis, prognosis and treatment of meningioma. In Addition to use of these proteins as biomarkers, role of exosomes in currently available therapeutic approaches has been discussed.

GAB1 overexpression identifies hedgehog-activated anterior skull base meningiomas

AIMS

Mutations activating the hedgehog (Hh) signalling pathway have been described in anterior skull base meningiomas, raising hope for the use of targeted therapies. However, identification of Hh-activated tumours is hampered by the lack of a reliable immunohistochemical marker. We report the evaluation of GAB1, an immunohistochemical marker used to detect Hh pathway activation in medulloblastoma, as a potential marker of Hh-activated meningiomas.

METHODS

GAB1 staining was compared to SMO mutation detection with Sanger and NGS techniques as well as Hh pathway activation study through mRNA expression level analyses in a discovery set of 110 anterior skull base meningiomas and in a prospective validation set of 21 meningiomas.

RESULTS

Using an expression score ranging from 0 to 400, we show that a cut-off score of 250 lead to excellent detection of Hh pathway mutations (sensitivity 100%, specificity 86%). The prospective validation set confirmed the excellent negative predictive value of GAB1 to exclude Hh-independent meningiomas. We describe a large series of 32 SMO-mutant meningiomas and define multiple ways of Hh activation, either through somatic mutations or associated with mutually co-exclusive sonic hedgehog (SHH) or Indian hedgehog (IHH) overexpression independent of the mutations.

CONCLUSION

The assessment of GAB1 expression by an immunohistochemical score is a fast and cost-efficient tool to screen anterior skull base meningiomas for activation of the Hh pathway. It could facilitate the identification of selected cases amenable to sequencing for Hh pathway genes as predictive markers for targeted therapy.

Molecular genetics of meningiomas

Comprehensive genomic studies of meningioma have offered important insights about the molecular mechanisms underlying this common brain tumor. The use of next-generation sequencing techniques has identified driver mutations in approximately 80% of benign sporadic lesions, as well as epigenetic, regulatory, and copy number events that are associated with formation and disease progression. The events described to date fall into five mutually exclusive molecular subgroups that correlate with tumor location and embryological origin. Importantly, these subgroups also carry implications for clinical management, as they are predictive of histologic subtype and the likelihood of progression. Further work is necessary to understand the molecular mechanisms by which identified mutations drive tumorigenesis as well as the genomic pathways that transform benign lesions into malignancies. Progress made during the past decade has opened the door to potential molecular therapies as well as integration of meningioma genotyping data into clinical management decisions. Several pharmacologic trials are currently underway that leverage recent genomic findings to target established oncogenic pathways in refractory tumors. With the combined efforts of physicians and basic science investigators, the clinical management of meningioma will continue to make important strides in the coming years.

MPscore: A Novel Predictive and Prognostic Scoring for Progressive Meningioma

Simple Summary

Subtyping for meningioma is urgently required to stratify the patients with high risks of recurrence and progression due to the intertumoral heterogeneity in meningioma. Here, we performed a consensus clustering of 179 meningiomas and identified progressive subtype (subtype 3) based the transcriptome profiles. Loss of chromosome 1q along with Neurofibromin 2 (NF2) mutation or loss of chromosome 22p is exclusively presented in subtype 3 meningioma. DNA methylation analyses of meningioma subtypes also suggested hypermethylation was observed in subtype 3 meningioma. Our findings identified low expression of Alkaline Phosphatase (ALPL) is the most significant feature in progressive subtype of meningioma. We constructed and validated a meningioma progression score (MPscore) to characterize the progressive phenotype in meningioma. The predictive accuracy has also been validated in three independent cohorts. Therefore, MPscore can be potentially useful for meningioma recurrence prediction and stratification.

Abstract

Meningioma is the most common tumor in central nervous system (CNS). Although most cases of meningioma are benign (WHO grade I) and curable by surgical resection, a few tumors remain diagnostically and therapeutically challenging due to the frequent recurrence and progression. The heterogeneity of meningioma revealed by DNA methylation profiling suggests the demand of subtyping for meningioma. Therefore, we performed a clustering analyses to characterize the progressive features of meningioma and constructed a meningioma progression score to predict the risk of the recurrence. A total of 179 meningioma transcriptome from RNA sequencing was included for progression subtype clustering. Four biologically distinct subtypes (subtype 1, subtype 2, subtype 3 and subtype 4) were identified. Copy number alternation and genomewide DNA methylation of each subtype was also characterized. Immune cell infiltration was examined by the microenvironment cell populations counter. All anaplastic meningiomas (7/7) and most atypical meningiomas (24/32) are enriched in subtype 3 while no WHO II or III meningioma presents in subtype 1, suggesting subtype 3 meningioma is a progressive subtype. Stemness index and immune response are also heterogeneous across four subtypes. Monocytic lineage is the most immune cell type in all meningiomas, except for subtype 1. CD8 positive T cells are predominantly observed in subtype 3. To extend the clinical utility of progressive meningioma subtyping, we constructed the meningioma progression score (MPscore) by the signature genes in subtype 3. The predictive accuracy and prognostic capacity of MPscore has also been validated in three independent cohort. Our study uncovers four biologically distinct subtypes in meningioma and the MPscore is potentially helpful in the recurrence risk prediction and response to treatments stratification in meningioma.

A Practical Overview on the Molecular Biology of Meningioma

PURPOSE OF REVIEW

Meningioma is a common intracranial neoplasm currently classified in 15 histologic subtypes across 3 grades of malignancy. First-choice therapy for meningioma is maximum safe resection for grade I tumors, and surgery plus optional and mandatory adjuvant radiotherapy for grade II and III, respectively, given the increased rate of recurrence even in the event of complete resection. The WHO 2016 histopathologic grading of meningioma has been questioned due to subjectivity and its controversial predictive power for recurrence.

RECENT FINDINGS

Novel DNA methylation profiling has simplified classification into six classes that seem to improve prognostic accuracy. We review five main topics of molecular biology research regarding tumorigenesis and natural history of meningioma from the clinician's perspective: the histopathologic diagnostic features and pitfalls of the current tumor classification; the molecular integrated diagnosis supported by identification of genetic alterations and DNA methylation profiling; the general landscape of the various signaling pathways involved in meningioma formation; the pathogenic theories of the peri-tumoral edema present in meningioma and its therapy implications; and a summarized review on the current treatments and plausible targeted therapies directed to meningioma. It seems likely that molecular assessment will be introduced within the next update of the WHO classification of meningiomas, acknowledging the promising value of DNA methylation profiling. This integrated diagnostic protocol will simplify tumor subtype categorization and provide improved accuracy in predicting recurrence and outcome. Although much effort is being done in identifying key gene mutations, and elucidating specific intracellular signaling pathways involved in meningioma tumorigenesis, effective targeted therapies for recurrent meningiomas are still lacking.

Meningioma: A Review of Clinicopathological and Molecular Aspects

Meningiomas are the most the common primary brain tumors in adults, representing approximately a third of all intracranial neoplasms. They classically are found to be more common in females, with the exception of higher grades that have a predilection for males, and patients of older age. Meningiomas can also be seen as a spectrum of inherited syndromes such as neurofibromatosis 2 as well as ionizing radiation. In general, the 5-year survival for a WHO grade I meningioma exceeds 80%; however, survival is greatly reduced in anaplastic meningiomas. The standard of care for meningiomas in a surgically-accessible location is gross total resection. Radiation therapy is generally saved for atypical, anaplastic, recurrent, and surgically inaccessible benign meningiomas with a total dose of ~60 Gy. However, the method of radiation, regimen and timing is still evolving and is an area of active research with ongoing clinical trials. While there are currently no good adjuvant chemotherapeutic agents available, recent advances in the genomic and epigenomic landscape of meningiomas are being explored for potential targeted therapy.

Gross and Histological Examination of a Large Spheno-Orbital Meningioma

Meningiomas arise from arachnoid cap cells and are the most common heavily researched intracranial tumors. Most of these neoplasms are benign and are classified as World Health Organization (WHO) grade I. They are often found in parasagittal and falx regions, over cerebral convexities, and in the sphenoid ridges. Spheno-orbital meningiomas (SOMs) occupy the cranium and the orbit and are less commonly encountered. Nonetheless, in this case study, a 9.5 cm × 5 cm SOM occurring in a 93-year-old female cadaver was identified and examined. The tumor spanned from the left middle cranial fossa, through the anterior fossa and invaded the orbit. It caused proptosis of the left eye, compression of the temporal lobe, and damage to the optic nerve. Histological examination of the tumor revealed characteristics of a WHO grade I meningothelial meningioma.

Paediatric meningiomas in Singapore - Case series of a rare entity

Paediatric meningiomas are extremely rare. These tumours constitute only 2 to 3% of all childhood brain tumours. Despite similarities in histological features between PMs and their adult counterparts, there are important distinctions between them. In this case series, the authors describe their experience in paediatric meningiomas in Singapore's 2 children's hospitals from 1998 to 2018. The primary aim of this retrospective study is to evaluate the clinical, radiological and pathological characteristics, and associated outcomes of paediatric patients diagnosed with meningioma managed in our local institutions. Following that, the study's findings are secondary aims are corroborated with published literature. A total of 10 patients (4 males and 6 females) were identified for this study within the period of 01 January 1998 to 31 December 2018. Their ages ranged from 1 year old to 18 years old (median age 10.5 years old). Two of the patients had NF1 and NF2 respectively. There were 9 intracranial and 1 intraspinal paediatric meningiomas. Seven patients achieved gross total resection and 3 patients had subtotal resection. Eight patients did not have tumour recurrence or increase in size of tumour remnant during the course of their follow-up. In congruency with the literature, up to 40% of our patients had higher grade meningiomas and 55.6% had large tumour volumes more than 30 cm³. Owing to the paucity of knowledge for this unusual tumour, the authors emphasize the need for closer surveillance and in-depth genomic studies to identify novel therapies for this challenging condition.

In vivo imaging of cell proliferation in meningioma using 3'-deoxy-3'-[18F]fluorothymidine PET/MRI

PURPOSE

Positron emission tomography (PET) with 3'-deoxy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) provides a noninvasive assessment of tumour proliferation in vivo and could be a valuable imaging modality for assessing malignancy in meningiomas. We investigated a range of static and dynamic [¹⁸F]FLT metrics by correlating the findings with cellular biomarkers of proliferation and angiogenesis.

METHODS

Seventeen prospectively recruited adult patients with intracranial meningiomas underwent a 60-min dynamic [¹⁸F]FLT PET following surgery. Maximum and mean standardized uptake values (SUV_max, SUV_mean) with and without normalization to healthy brain tissue and blood radioactivity obtained from 40 to 60 min summed dynamic images (PET_40-60) and ~ 60-min blood samples were calculated. Kinetic modelling using a two-tissue reversible compartmental model with a fractioned blood volume (V_B) was performed to determine the total distribution volume (V_T). Expressions of proliferation and angiogenesis with key parameters including Ki-67 index, phosphohistone-H3 (phh3), MKI67, thymidine kinase 1 (TK1), proliferating cell nuclear antigen (PCNA), Kirsten RAt Sarcoma viral oncogene homolog (KRAS), TIMP metallopeptidase inhibitor 3 (TIMP3), and vascular endothelial growth factor A (VEGFA) were determined by immunohistochemistry and/or quantitative polymerase chain reaction.

RESULTS

Immunohistochemistry revealed 13 World Health Organization (WHO) grade I and four WHO grade II meningiomas. SUV_max and SUV_mean normalized to blood radioactivity from PET_40-60 and blood sampling, and V_T were able to significantly differentiate between WHO grades with the best results for maximum and mean tumour-to-whole-blood ratios (sensitivity 100%, specificity 94-95%, accuracy 99%; P = 0.003). Static [¹⁸F]FLT metrics were significantly correlated with proliferative biomarkers, especially Ki-67 index, phh3, and TK1, while no correlations were found with VEGFA or V_B. Using Ki-67 index with a threshold > 4%, the majority of [¹⁸F]FLT metrics showed a high ability to identify aggressive meningiomas with SUV_mean demonstrating the best performance (sensitivity 80%, specificity 81%, accuracy 80%; P = 0.024).

CONCLUSION

[¹⁸F]FLT PET could be a useful imaging modality for assessing cellular proliferation in meningiomas.

Molecular characteristics of meningiomas

Meningioma is the most common primary intracranial tumor in adults. The grading of meningioma is based on World Health Organization criteria, which rely on histopathological features alone. This grading system is unable to conclusively predict the clinical behavior of these tumors (i.e., recurrence or prognosis in benign or atypical grades). Advances in molecular techniques over the last decade that include genomic and epigenomic data associated with meningiomas have been used to identify genetic biomarkers that can predict tumor behavior. This review summarizes the molecular characteristics of meningioma using genetic and epigenetic biomarkers. Molecular alterations that can predict meningioma behavior may be integrated into the upcoming World Health Organization grading system.

Nucleotide variations of TP53 exon 4 found in intracranial meningioma and in silico prediction of their significance

The aim of the present study was to identify TP53 exon 4 mutations in patients with meningioma and to investigate their potential association with specific tumor pathology. Nucleotide alterations were investigated in 48 meningiomas via the direct sequencing of TP53 exon 4 in patient tumor and blood samples using the DNA Sanger method with the BigDyeTerminator v3.1 Cycle Sequencing kit and Applied Biosystems 3730XL apparatus. The results revealed that TP53 exon 4 was frequently altered in meningioma, occurring in 60.4% of the patients investigated. A total of 18 different alterations were detected in the meningioma samples assessed in the current study. The majority of these appeared more than once and some were repeatedly identified in several patients. Changes at codons 72 (c.215G>C) and 62 (c.186delA) were highly prevalent, occurring in 44.8% of patients. Other changes detected via frequency analysis included: Five substitutions on codon 105 (c.315C>T); four insertions on codon 70 (c.209_210insG); three insertions on codon 64 (c.190C>G), 82 (245C>T; 245delC; 243_244insA) and 104 (c.312G>A); and two insertions on codons 108 (c.322G>C), 71 (c.213C>A), 73 (c.217G>A), 91 (c.271T>C) and 100 (c.300G>T). Codons 68 (c.202_203insT), 77 (c.229C>T), 88 (c.263C>G) and 92 (c.276C>A) were altered once. Alterations on codons 82, 91, 108, 104, 105, 70 and 92 were characterized as possibly damaging by PolyPhen-2 and Mutation Taster2 tools. The current study also demonstrated that nucleotide alterations were significantly associated with the loss of p53 expression (P=0.04) and female patients (P=0.049), particularly codon 72. The results present novel data on the mutational spectrum of TP53 in meningeal brain tumors.

New insights into the genomic landscape of meningiomas identified FGFR3 in a subset of patients with favorable prognoses

Background: With a prevalence of 170 000 adults in the US alone, meningiomas are the most common primary intracranial tumors. The management of skull base meningiomas is challenging due to their complexity and proximity to crucial nearby structures. The identification of oncogenic mutations has provided further insights into the tumorigenesis of meningioma and the possibility of targeted therapy.

This study aimed to further investigate the association of mutational profiles with anatomical distribution, histological subtype, WHO grade, and recurrence in patients with meningioma.

Methods: Tissue samples were collected from 71 patients diagnosed with meningioma from 2008 to 2016. A total of 51 cases were skull based. Samples were subjected to targeted sequencing using a next generation customized cancer gene panel (n = 66 genes analyzed).

Results: We detected genomic alterations (GAs) in 68 tumors, averaging 1.56 ± 1.07 genomic alterations (GAs) per sample. NF2 was the most frequently altered gene (36/71 cases). Interestingly, we identified a number of mutations in non-NF2 genes, including a hotspot TERTp c.−124: G > A mutation that may be related to poor prognosis and FGFR3 mutations that may represent biomarkers of a favorable prognosis as reported in other cancers.

Conclusions: We demonstrate that comprehensive genomic profiling in our population can reveal a potential new prognostic biomarkers of skull base meningioma. These mutations can enhance diagnostic accuracy and clinical decision-making. Among our findings were the identification of a TERTp mutation and the first report of FGFR3 mutations that may represent biomarkers for the identification of skull base meningioma patients with a favorable prognosis.

Proteomic analysis of meningiomas reveals clinically distinct molecular patterns

BACKGROUND

Meningiomas represent one of the most common brain tumors and exhibit a clinically heterogeneous behavior, sometimes difficult to predict with classic histopathologic features. While emerging molecular profiling efforts have linked specific genomic drivers to distinct clinical patterns, the proteomic landscape of meningiomas remains largely unexplored.

METHODS

We utilize liquid chromatography tandem mass spectrometry with an Orbitrap mass analyzer to quantify global protein abundances of a clinically well-annotated formalin-fixed paraffin embedded (FFPE) cohort (n = 61) of meningiomas spanning all World Health Organization (WHO) grades and various degrees of clinical aggressiveness.

RESULTS

In total, we quantify 3042 unique proteins comparing patterns across different clinical parameters. Unsupervised clustering analysis highlighted distinct proteomic (n = 106 proteins, Welch's t-test, P < 0.01) and pathway-level (eg, Notch and PI3K/AKT/mTOR) differences between convexity and skull base meningiomas. Supervised comparative analyses of different pathological grades revealed distinct patterns between benign (grade I) and atypical/malignant (grades II‒III) meningiomas with specific oncogenes enriched in higher grade lesions. Independent of WHO grade, clinically aggressive meningiomas that rapidly recurred (<3 y) had distinctive protein patterns converging on mRNA processing and impaired activation of the matrisome complex. Larger sized meningiomas (>3 cm maximum tumor diameter) and those with previous radiation exposure revealed perturbed pro-proliferative (eg, epidermal growth factor receptor) and metabolic as well as inflammatory response pathways (mitochondrial activity, interferon), respectively.

CONCLUSIONS

Our proteomic study demonstrates that meningiomas of different grades and clinical parameters present distinct proteomic profiles. These proteomic variations offer potential future utility in helping better predict patient outcome and in nominating novel therapeutic targets for personalized care.

Spinal Versus Intracranial Meningioma: Aberrant Expression of CD10 and Inhibin with Relation to Clinicopathological Features and Prognosis

CD10 and inhibin are used mainly in CNS pathology to distinguish hemangioblastoma from metastatic clear cell renal cell carcinoma. Some meningiomas can mimic both tumors and so we aimed at this study to investigate the expression of both markers in a large number of meningioma cases. One hundred thirty-four meningioma samples were collected, 14 of them were spinal and 120 were intracranial. Manual TMA blocks were constructed using modified mechanical pencil tip method and immunohistochemistry for CD10 and inhibin was done. Intracranial meningioma occurred in significantly younger age than spinal ones. Most of spinal meningiomas were of transitional histology. CD10 was expressed in 14% of cases with significant positivity in spinal rather than intracranial cases. Transitional meningiomas showed the highest positivity for CD10 expression, while the least positive was the meningiotheliomatous type. Inhibin was expressed in 6% of cases with no significant relation to clinicopathological and histological features. There was no significant relationship between the expression of CD10 and inhibin expression in meningiomas. In conclusion, spinal meningiomas differ than intracranial ones in many clinicopathological and biological aspects. Among these differences is CD10 expression being more expressed in spinal meningiomas. However CD10 and inhibin are aberrantly expressed in a proportion of meningiomas, both have no relations to poor prognostic factors but more caution should be exerted during usage of these markers in diagnosis of hemangioblastoma and metastatic RCC. Further studies are suggested for exploring more biological differences between spinal and intracranial meningiomas.

Are convexity meningiomas all the same? A clinico-radiological analysis of surgically treated eloquent areas convexity meningiomas

BACKGROUND

Convexity meningiomas are considered low-risk tumors, with high possibility of cure and low risk of relapse after resection. Very few studies have investigated meningiomas located in or around highly eloquent regions (namely perirolandic and perisylvian fissures). This study aimed to determine the differences in preoperative characteristics and postoperative outcomes between convexity meningiomas at eloquent area and non-eloquent areas.

METHODS

Retrospective study on patients who underwent surgical resection for convexity meningioma. Patients were divided into eloquent and non-eloquent area. Statistical analysis was made comparing preoperative and postoperative data of both groups.

RESULTS

The study included a total of 117 patients: 80 with eloquent area tumor and 37 with non- eloquent area tumor. Statistically significant differences were detected between the groups in preoperative KPS (93 ± 10 in eloquent vs. 97 ± 6 in non-eloquent; p = .008) and in large-caliber vein involvement (76.3% in cases vs. 16.2% in controls; p < .001). Postoperatively, patients with eloquent area tumors showed initial deterioration in neurological status followed by recovery; final outcomes were comparable to that of patients with non-eloquent area tumors. However, patients with eloquent area meningiomas had higher propensity to suffer from seizures postoperatively. Postoperative complications and long-term outcomes were not significantly different between the two groups.

CONCLUSIONS

Patients with eloquent areas convexity meningiomas do not appear to have higher surgical risk. Neurological status is more likely to worsen immediately after surgery but long-term recovery is satisfactory. Seizure control after surgery appears to be poorer in patients with perirolandic meningioma.

Histomolecular characterization of intracranial meningiomas developed in patients exposed to high-dose cyproterone acetate: an antiandrogen treatment

Background

Meningiomas are the most common primary intracranial tumors in adults. The relationship between meningiomas and exogenous sex hormones such as cyproterone acetate (CPA) is well documented, yet the underlying mechanisms remain unknown. Defining the histomolecular status of meningiomas developed on CPA would help us to better understand the oncogenesis of these tumors.

Methods

We identified 30 patients operated for a meningioma after long-term high-dose CPA therapy and with a history of CPA discontinuation before establishing the indication for surgical intervention. We used array-comparative genomic hybridization (to characterize copy number changes in those 30 meningiomas and subsequently performed next-generation sequencing with the National Institute of Cancer (INCa) solid tumor panel, which is a targeted panel of clinically actionable genes. We also examined grade, type, and clinical features.

Results

We identified AKT1 mutations or PIK3CA mutations in 33.3% of CPA meningiomas. AKT1 and PIK3CA mutations were mutually exclusive. Enrichment in oncogenic PIK3CA mutations in the CPA cohort was detected. CPA meningiomas showed chromosomal stability and were located mainly in the skull base. Ninety percent of CPA meningiomas were low-grade meningiomas and 63.4% were meningotheliomas. Half of our CPA cohort had microcystic components.

Conclusion

Our study shows that low-grade meningothelial meningiomas of the skull base are predominant in CPA meningiomas. We identified PIK3CA/AKT1 pathway as a hypothetical actor in onco-pharmacological interaction between meningiomas and CPA. This signaling pathway could be an interesting target for precision medicine trials in meningioma patients who have been subjected to CPA. Our results could invite the scientific community to review the current classification of meningiomas and to evolve toward more specific histomolecular classification.

Transcriptome signatures associated with meningioma progression

Meningiomas are the most common primary brain tumor of adults. The majority are benign (WHO grade I), with a mostly indolent course; 20% of them (WHO grade II and III) are, however, considered aggressive and require a more complex management. WHO grade II and III tumors are heterogeneous and, in some cases, can develop from a prior lower grade meningioma, although most arise de novo. Mechanisms leading to progression or implicated in de novo grade II and III tumorigenesis are poorly understood. RNA-seq was used to profile the transcriptome of grade I, II, and III meningiomas and to identify genes that may be involved in progression. Bioinformatic analyses showed that grade I meningiomas that progress to a higher grade are molecularly different from those that do not. As such, we identify GREM2, a regulator of the BMP pathway, and the snoRNAs SNORA46 and SNORA48, as being significantly reduced in meningioma progression. Additionally, our study has identified several novel fusion transcripts that are differentially present in meningiomas, with grade I tumors that did not progress presenting more fusion transcripts than all other tumors. Interestingly, our study also points to a difference in the tumor immune microenvironment that correlates with histopathological grade.

Analysis of Minichromosome Maintenance-2 (MCM-2) and Cyclin D1 Expression in Meningioma

World Health Organization histopathological grading of meningioma is associated with recurrence and clinical outcome. Grade II meningioma can be difficult to distinguish with grade I especially in case in which mitosis is not easily identified. MCM-2 and Cyclin D1 play crucial role in cell cycle and have been reported overexpressed in many malignant tumors. The aim of this observational analytic study was to analyze the differences and correlation between MCM-2 and Cyclin D1 in various meningioma grading. Immunohistochemystry with MCM-2 and Cyclin D1 was performed on 25 paraffin blocks of grade I, II and III meningiomas at the Laboratory of Anatomical Pathology, Dr. Soetomo Hospital. The immunoexpression are evaluated using Labelling Index, then analyzed statistically. The results showed significant difference in expression of MCM-2 within various meningioma grading (p=0.000) and significant difference in expression of Cyclin D1 within grade I and II also within grade I and III (p<0.050), but not in grade II and III (p>0.050). There was also positive correlation between MCM-2 and Cyclin D1 expression in various meningioma grading (rs=0.683, p=0.000). MCM-2 may play role in distinguishing various meningioma grading. Cyclin D1 can distinguish grade I and II also grade I and III, but not grade II and III. Overexpression MCM-2 was along with Cyclin D1 in various meningioma gradings.

Traditional and systems biology based drug discovery for the rare tumor syndrome neurofibromatosis type 2

Neurofibromatosis 2 (NF2) is a rare tumor suppressor syndrome that manifests with multiple schwannomas and meningiomas. There are no effective drug therapies for these benign tumors and conventional therapies have limited efficacy. Various model systems have been created and several drug targets have been implicated in NF2-driven tumorigenesis based on known effects of the absence of merlin, the product of the NF2 gene. We tested priority compounds based on known biology with traditional dose-concentration studies in meningioma and schwann cell systems. Concurrently, we studied functional kinome and gene expression in these cells pre- and post-treatment to determine merlin deficient molecular phenotypes. Cell viability results showed that three agents (GSK2126458, Panobinostat, CUDC-907) had the greatest activity across schwannoma and meningioma cell systems, but merlin status did not significantly influence response. In vivo, drug effect was tumor specific with meningioma, but not schwannoma, showing response to GSK2126458 and Panobinostat. In culture, changes in both the transcriptome and kinome in response to treatment clustered predominantly based on tumor type. However, there were differences in both gene expression and functional kinome at baseline between meningioma and schwannoma cell systems that may form the basis for future selective therapies. This work has created an openly accessible resource (www.synapse.org/SynodosNF2) of fully characterized isogenic schwannoma and meningioma cell systems as well as a rich data source of kinome and transcriptome data from these assay systems before and after treatment that enables single and combination drug discovery based on molecular phenotype.

CASP8, XRCC1, WRN, NF2, and BRIP1 Polymorphisms Analysis Shows Their Genetic Susceptibility for Meningioma Risk and the Association with Tumor-Related Phenotype in a Chinese Population

OBJECTIVE

To investigate 10 candidate single nucleotide polymorphisms (SNPs) in 5 genes (CASP8, XRCC1, WRN, NF2, and BRIP1) to confirm the association between the 5 genes and the meningioma risk in a Chinese population.

METHODS

We examined 10 candidate SNPs in 5 genes (CASP8, XRCC1, WRN, NF2, and BRIP1) to confirm the association between the 5 genes and the meningioma risk and tumor-related phenotype in 433 individuals, including 215 patients with meningioma and 218 controls.

RESULTS

The polymorphisms rs4968451T>G in BRIP1 were significantly associated with the risk of meningioma (TT vs. TG vs. GG additive, P = 0.005; TT+TG vs. GG dominant, P = 0.015; TT/GT+GG recessive, P = 0.034). The significant association was found only in females for BRIP1 rs4968451T>G (TT+TG vs. GG dominant, P = 0.001; TT/GT+GG recessive, P = 0.044). We observed no significant association between genotypes and the meningioma risk for the other 9 SNPs. Through genotype-phenotype analysis, the genotype of BRIP1 rs4968451T>G was also strongly associated with tumor-related phenotypes, including the tumor grade and tumor subtypes. BRIP1 rs4968451T>G was associated with markedly grade I meningioma risk (TT+TG vs. GG dominant, P = 0.008; TT/GT+GG recessive, P = 0.020). In addition, BRIP1 rs4968451T>G was associated with markedly meningothelial and transitional meningioma risk. Furthermore, the genotype of CAPS8, XRCC1, and NF2 was associated with different subtype of meningioma risk.

CONCLUSIONS

This study indicated a role for BRIP1 gene variations in meningioma and may be informative for future genetic or biological studies of meningioma. These findings will assist in further understanding the genetic cause for meningiomas and guide more effective biological interventions to facilitate meningiomas.

Brain cancer genomics and epigenomics

Classically, brain cancers have been graded and diagnosed based on histology and risk stratified by clinical criteria. Recent advances in genomics and epigenomics have ushered in an era of defining cancers based on molecular criteria. These advances have increased our precision of identifying oncogenic driving events and, most importantly, increased our precision at predicting clinical outcome. For the first time in its history, the 2016 revision of the WHO Classification of Tumors of the Central Nervous System included molecular features as tumor classification criteria. Brain tumors can develop in the context of genetic cancer predisposition syndromes, such as Li-Fraumeni or Gorlin syndrome, but by far most commonly arise through the acquisition of somatic mutations and chromosome changes in the malignant cells. By taking a survey across this cancer landscape, certain themes emerge as being common events to drive cancer: DNA damage repair, genomic instability, mechanistic target of rapamycin pathway, sonic hedgehog pathway, hypoxia, and epigenetic dysfunction. Understanding these mechanisms is of paramount importance for improving targeted therapies, and for identifying the right patients for those therapies.

MiR-34a-3p alters proliferation and apoptosis of meningioma cells in vitro and is directly targeting SMAD4, FRAT1 and BCL2

Micro (mi)RNAs are short, noncoding RNAs and deregulation of miRNAs and their targets are implicated in tumor generation and progression in many cancers. Meningiomas are mostly benign, slow growing tumors of the central nervous system with a small percentage showing a malignant phenotype.

Following in silico prediction of potential targets of miR-34a-3p, SMAD4, FRAT1, and BCL2 have been confirmed as targets by dual luciferase assays with co-expression of miR-34a-3p and reporter gene constructs containing the respective 3'UTRs. Disruption of the miR-34a-3p binding sites in the 3'UTRs resulted in loss of responsiveness to miR-34a-3p overexpression. In meningioma cells, overexpression of miR-34a-3p resulted in decreased protein levels of SMAD4, FRAT1 and BCL2, while inhibition of miR-34a-3p led to increased levels of these proteins as confirmed by Western blotting. Furthermore, deregulation of miR-34a-3p altered cell proliferation and apoptosis of meningioma cells in vitro.

We show that SMAD4, FRAT1 and BCL2 are direct targets of miR-34a-3p and that deregulation of miR-34a-3p alters proliferation and apoptosis of meningioma cells in vitro. As part of their respective signaling pathways, which are known to play a role in meningioma genesis and progression, deregulation of SMAD4, FRAT1 and BCL2 might contribute to the aberrant activation of these signaling pathways leading to increased proliferation and inhibition of apoptosis in meningiomas.

Tumour stem cells in meningioma: A review

Meningioma is a common intracranial and intraspinal neoplasm accounting for 25-30% of all primary neurological tumours. It is associated with high rates of recurrence especially in higher-grade tumours and lesions located at the skull base. Cancer stem cells are increasingly recognised as the origin of cancer and are attributed to loco-regional recurrence, metastasis and treatment resistance. This review presents the accumulating evidence of the presence of tumour stem cells within meningioma and the stem cell markers being used to characterise this putative primitive population within this common tumour.

RNA-seq transcriptome analysis of formalin fixed, paraffin-embedded canine meningioma

Meningiomas are the most commonly reported primary intracranial tumor in dogs and humans and between the two species there are similarities in histology and biologic behavior. Due to these similarities, dogs have been proposed as models for meningioma pathobiology. However, little is known about specific pathways and individual genes that are involved in the development and progression of canine meningioma. In addition, studies are lacking that utilize RNAseq to characterize gene expression in clinical cases of canine meningioma. The primary objective of this study was to develop a technique for which high quality RNA can be extracted from formalin-fixed, paraffin embedded tissue and then used for transcriptome analysis to determine patterns of gene expression. RNA was extracted from thirteen canine meningiomas-eleven from formalin fixed and two flash-frozen. These represented six grade I and seven grade II meningiomas based on the World Health Organization classification system for human meningioma. RNA was also extracted from fresh frozen leptomeninges from three control dogs for comparison. RNAseq libraries made from formalin fixed tissue were of sufficient quality to successfully identify 125 significantly differentially expressed genes, the majority of which were related to oncogenic processes. Twelve genes (AQP1, BMPER, FBLN2, FRZB, MEDAG, MYC, PAMR1, PDGFRL, PDPN, PECAM1, PERP, ZC2HC1C) were validated using qPCR. Among the differentially expressed genes were oncogenes, tumor suppressors, transcription factors, VEGF-related genes, and members of the WNT pathway. Our work demonstrates that RNA of sufficient quality can be extracted from FFPE canine meningioma samples to provide biologically relevant transcriptome analyses using a next-generation sequencing technique, such as RNA-seq.

SMO mutation status defines a distinct and frequent molecular subgroup in olfactory groove meningiomas

Background

Meningiomas are the most common primary intracranial tumors in adults. Identification of SMO and AKT1 mutations in meningiomas has raised the hope for targeted therapies. It would be useful to know the precise frequency of these mutations in anatomical subgroups and clarify their prognostic value.

Methods

We used the Sanger sequencing technique to characterize 79 samples of olfactory groove meningiomas for SMO (L412F and W535L) and AKT1E17K mutations. We reviewed clinical data to assess the prognostic value of these mutations in this anatomical subgroup.

Results

Out of the 79 patients with olfactory groove meningiomas, we identified targetable mutations in 34 patients (43%) (22 patients [28%] with SMO mutation-L412F almost exclusively-and 12 patients [15%] with AKT1 mutation). Meningiomas in the SMO-mutant group had an overall 36% recurrence rate, significantly higher than in the AKT1-mutant group (16%) and in the "SMO and AKT1 wildtype" group (11%) (χ2 test, P = .04). All late recurrences (after 5 y) occurred in the SMO-mutant group. Among grade I meningiomas, the SMO-mutant group was identified as having a significantly poorer prognosis. World Health Organization histological grade II (P = .006) and incomplete resection (P = .001) were independently associated with shorter recurrence-free survival.

Conclusion

Molecular diagnosis of SMOL412F/W535L and AKT1E17K mutations improves prognostic evaluation in olfactory groove meningiomas and opens new therapeutic perspectives with SMO or AKT inhibitors for recurrent cases.

[Tumors of the inner ear and adjacent structures]

Tumors of the inner ear and adjacent structures often present with hearing loss, tinnitus and vertigo due to compression of the traversing cranial nerves. More than 90% of the tumors of the inner ear with or without expansion into the cerebellopontine angle are histologically diagnosed as vestibular schwannomas. Less common tumorous lesions include ectopic meningiomas located in the petrous bone, glomus tympanicum paragangliomas or endolymphatic sac tumors (ELST) originating in the vestibular recess. Most tumors are sporadic, but hereditary disorders have to be considered. Bilateral vestibular schwannomas are indicative of neurofibromatosis type 2 and ELST in conjunction with other abdominal tumors indicates von Hippel-Lindau disease. The neuropathological diagnostics and grading guides the subsequent therapy of these mostly benign lesions.

Modulation of Dkk-3 and claudin-5 as new therapeutic strategy in the treatment of meningiomas

Meningiomas are the most common tumors of the central nervous system, where the incidence is around 25% of all primary brain tumors. The optimal treatment is represented by total resection accompanied by the removal of the dura mater and bone when infiltrated by the tumor. The histological grading is the most important prognostic factor in the outcome. However, recurrences do occur in a significant proportion (10–25%) of cases, representing the most relevant clinical complication. Molecular therapies are providing to give different opportunities in the development of new treatments. The Dickkopf-related family of proteins includes four secretory proteins. The expression of the REIC/Dkk-3 gene is down-regulated in many tumor cell lines and could contribute to the immunomodulatory properties of the tissue microenvironment. An important role in carcinogenesis is played by Dickkopf protein-related protein 3, which is involved in embryonic development through its interaction and modulation of the pathway of the Wnt signal transduction. The mutations of this pathway are of clinical importance, because they lead to the onset of several cancers, including brain tumors, being also involved in tumor angiogenesis. The claudin-5, is an integral membrane protein, which regulate the permeability of the blood-brain barrier. In various pathological processes, including inflammation, trauma and tumor, claudin 5 regulate the change in endothelial or epithelial permeability, therefore, modification in claudin-5 expression may play a role in malignant transformation. The aim of our study is to demonstrate the role of Dkk-3 and claudin-5 in the pathogenesis of meningiomas. A more correct identification of the role of these proteins might suggest interesting and new molecular targets for future therapeutic protocols.

Classification of Meningiomas Based on Their Surgical Removal, World Health Organization Grade, and Cytogenetic Profile: A Treatment Algorithm

BACKGROUND

Meningiomas are the most common primary intracranial tumor, but the lack of prospective randomized trials has led to different guidelines for their treatment. We proposed a classification of meningiomas that considers surgical removal, histology, and cytogenetic profile, based on a literature review of these 3 criteria. The classification can be used to guide adjuvant treatment and follow-up.

METHODS

A retrospective literature review was performed of PubMed from 2007 to 2016. Search terms were "meningioma," "surgery," "WHO classification," "cytogenetic," and "algorithm."

RESULTS

Meningiomas were classified into 5 groups (A-E) according to the Simpson resection grade, World Health Organization grade, and cytogenetic profile. Adjuvant therapy, follow-up magnetic resonance imaging, and management of recurrence and/or regrowth were proposed according to the classification.

CONCLUSIONS

The proposed meningioma classification was based on our experience and retrospective evidence collated from the literature and supported by recommendations. The application of the classification criteria yielded an algorithm for treatment and follow-up of patients with meningioma.

The Emerging Role of TRAF7 in Tumor Development

The seven members of the tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of intracellular proteins were originally discovered and characterized as signaling adaptor molecules coupled to the cytoplasmic regions of receptors of the TNF-R superfamily. Functionally, TRAFs act both as a scaffold and/or enzymatic proteins to regulate activation of mitogen-activated protein kinases (MAPKs) and transcription factors of nuclear factor-κB family (NF-κB). Given the wide variety of stimuli intracellularly conveyed by TRAF proteins, they are physiologically involved in multiple biological processes, including embryonic development, tissue homeostasis, and regulation of innate and adaptive immune responses. In the last few years, it has become increasingly evident the involvement of TRAF7, the last member of the TRAF family to be discovered, in the genesis and progression of several human cancers, placing TRAF7 in the spotlight as a novel tumor suppressor protein. In this paper, we review and discuss the literature recently produced on this subject. J. Cell. Physiol. 232: 1233-1238, 2017. © 2016 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.

Evaluation of autoantibody signatures in meningioma patients using human proteome arrays

Meningiomas are one of the most common tumors of the Central nervous system (CNS). This study aims to identify the autoantibody biomarkers in meningiomas using high-density human proteome arrays (~17,000 full-length recombinant human proteins). Screening of sera from 15 unaffected healthy individuals, 10 individuals with meningioma grade I and 5 with meningioma grade II was performed. This comprehensive proteomics based investigation revealed the dysregulation of 489 and 104 proteins in grades I and II of meningioma, respectively, along with the enrichment of several signalling pathways, which might play a crucial role in the manifestation of the disease. Autoantibody targets like IGHG4, CRYM, EFCAB2, STAT6, HDAC7A and CCNB1 were significantly dysregulated across both the grades. Further, we compared this to the tissue proteome and gene expression profile from GEO database. Previously reported upregulated proteins from meningioma tissue-based proteomics obtained from high-resolution mass spectrometry demonstrated an aggravated autoimmune response, emphasizing the clinical relevance of these targets. Some of these targets like SELENBP1 were tested for their presence in tumor tissue using immunoblotting. In the light of highly invasive diagnostic modalities employed to diagnose CNS tumors like meningioma, these autoantibody markers offer a minimally invasive diagnostic platform which could be pursued further for clinical translation.

Genetic variants and increased risk of meningioma: an updated meta-analysis

PURPOSE

Various genetic variants have been reported to be linked to an increased risk of meningioma. However, no confirmed conclusion has been obtained. The purpose of the study was to investigate potential meningioma-associated gene polymorphisms, based on published evidence.

MATERIALS AND METHODS

An updated meta-analysis was performed in September 2016. After electronic database searching and study screening, we selected eligible case-control studies and extracted data for meta-analysis, using Mantel-Haenszel statistics. P-values, pooled odds ratios (ORs), and 95% confidence intervals were calculated.

RESULTS

We finally selected eight genes with ten polymorphisms: MLLT10 rs12770228, CASP8 rs1045485, XRCC1 rs1799782, rs25487, MTHFR rs1801133, rs1801131, MTRR rs1801394, MTR rs1805087, GSTM1 null/present, and GSTT1 null/present. Results of meta-analyses showed that there was increased meningioma risk in case groups under all models of MLLT10 rs12770228 (all OR >1, P<0.001), compared with control groups. Similar results were observed under the allele, homozygote, dominant, and recessive models of MTRR rs1801394 (all OR >1, P<0.05), and the heterozygote and dominant models of MTHFR rs1801131 in the Caucasian population (all OR >1, P<0.05). However, no significantly increased meningioma risks were observed for CASP8 rs1045485, XRCC1 rs25487, rs1799782, MTHFR rs1801133, MTR rs1805087, or GSTM1/GSTT1 null mutations.

CONCLUSION

Our updated meta-analysis provided statistical evidence for the role of MLLT10 rs12770228, MTRR rs1801394, and MTHFR rs1801131 in increased susceptibility to meningioma.

Global epigenetic profiling identifies methylation subgroups associated with recurrence-free survival in meningioma

Meningioma is the most common primary brain tumor and carries a substantial risk of local recurrence. Methylation profiles of meningioma and their clinical implications are not well understood. We hypothesized that aggressive meningiomas have unique DNA methylation patterns that could be used to better stratify patient management. Samples (n = 140) were profiled using the Illumina HumanMethylation450BeadChip. Unsupervised modeling on a training set (n = 89) identified 2 molecular methylation subgroups of meningioma (MM) with significantly different recurrence-free survival (RFS) times between the groups: a prognostically unfavorable subgroup (MM-UNFAV) and a prognostically favorable subgroup (MM-FAV). This finding was validated in the remaining 51 samples and led to a baseline meningioma methylation classifier (bMMC) defined by 283 CpG loci (283-bMMC). To further optimize a recurrence predictor, probes subsumed within the baseline classifier were subject to additional modeling using a similar training/validation approach, leading to a 64-CpG loci meningioma methylation predictor (64-MMP). After adjustment for relevant clinical variables [WHO grade, mitotic index, Simpson grade, sex, location, and copy number aberrations (CNAs)] multivariable analyses for RFS showed that the baseline methylation classifier was not significant (p = 0.0793). The methylation predictor, however, was significantly associated with tumor recurrence (p < 0.0001). CNAs were extracted from the 450k intensity profiles. Tumor samples in the MM-UNFAV subgroup showed an overall higher proportion of CNAs compared to the MM-FAV subgroup tumors and the CNAs were complex in nature. CNAs in the MM-UNFAV subgroup included recurrent losses of 1p, 6q, 14q and 18q, and gain of 1q, all of which were previously identified as indicators of poor outcome. In conclusion, our analyses demonstrate robust DNA methylation signatures in meningioma that correlate with CNAs and stratify patients by recurrence risk.

Evaluation of DNMT3A genetic polymorphisms as outcome predictors in AML patients

DNMT3A mutation is known as a recurrent event in acute myelogenous leukemia (AML) patients. However, association between DNMT3A genetic polymorphisms and AML patients' outcomes is unknown. DNMT3A 11 SNPs (rs11695471, rs2289195, rs734693, rs2276598, rs1465825, rs7590760, rs13401241, rs7581217, rs749131, rs41284843 and rs7560488) were genotyped in 344 diagnostic non-FAB-M3 AML patients from southern China. Patients underwent combined chemotherapy with cytarabine and anthracyclines. DNMT3A mRNA expression was analyzed in PBMCs from randomly selected AML patients. Multivariate analysis and combined genotype analysis showed that rs2276598 was associated with increased while rs11695471 and rs734693 were associated with decreased chemosensitivity (P<0.05), while rs11695471 (worse for OS), rs2289195 (favorable for OS and DFS) and rs2276598 (favorable for DFS) were significantly associated with disease prognosis (P<0.05). In conclusion, DNMT3A polymorphisms may be potential predictive markers for AML patients' outcomes, which might improve prognostic stratification of AML.

EANO guidelines for the diagnosis and treatment of meningiomas

Although meningiomas are the most common intracranial tumours, the level of evidence to provide recommendations for the diagnosis and treatment of meningiomas is low compared with other tumours such as high-grade gliomas. The meningioma task force of the European Association of Neuro-Oncology (EANO) assessed the scientific literature and composed a framework of the best possible evidence-based recommendations for health professionals. The provisional diagnosis of meningioma is mainly made by MRI. Definitive diagnosis, including histological classification, grading, and molecular profiling, requires a surgical procedure to obtain tumour tissue. Therefore, in many elderly patients, observation is the best therapeutic option. If therapy is deemed necessary, the standard treatment is gross total surgical resection including the involved dura. As an alternative, radiosurgery can be done for small tumours, or fractionated radiotherapy in large or previously treated tumours. Treatment concepts combining surgery and radiosurgery or fractionated radiotherapy, which enable treatment of the complete tumour volume with low morbidity, are being developed. Pharmacotherapy for meningiomas has remained largely experimental. However, antiangiogenic drugs, peptide receptor radionuclide therapy, and targeted agents are promising candidates for future pharmacological approaches to treat refractory meningiomas across all WHO grades.