Merlin, DAL-1, and progesterone receptor expression in clinicopathologic subsets of meningioma: a correlative immunohistochemical study of 175 cases

Meningioma: International Consortium on Meningiomas consensus review on scientific advances and treatment paradigms for clinicians, researchers, and patients

Meningiomas are the most common primary intracranial tumors in adults and are increasing in incidence due to the aging population and increased access to neuroimaging. While most exhibit nonmalignant behavior, a subset of meningiomas are biologically aggressive and are associated with treatment resistance, resulting in significant neurologic morbidity and even mortality. In recent years, meaningful advances in our understanding of the biology of these tumors have led to the incorporation of molecular biomarkers into their grading and prognostication. However, unlike other central nervous system (CNS) tumors, a unified molecular taxonomy for meningiomas has not yet been established and remains an overarching goal of the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy-Not Official World Health Organization (cIMPACT-NOW) working group. Additionally, clinical equipoise still remains on how specific meningioma cases and patient populations should be optimally managed. To address these existing gaps, members of the International Consortium on Meningiomas including field-leading experts, have prepared this comprehensive consensus narrative review directed toward clinicians, researchers, and patients. Included in this manuscript are detailed overviews of proposed molecular classifications, novel biomarkers, contemporary treatment strategies, trials on systemic therapies, health-related quality-of-life studies, and management strategies for unique meningioma patient populations. In each section, we discuss the current state of knowledge as well as ongoing clinical and research challenges to road map future directions for further investigation.

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.

Hormone Receptor Expression in Meningiomas: A Systematic Review

Meningiomas are, in most cases, low grade intracranial tumors. However, relapses are frequent. To date, only a few prognostic markers are described in the literature. Several studies have discussed the expression of progesterone, estrogen, androgen, and somatostatin receptors. The utility of analyzing these expressions for prognostic, theragnostic, and therapeutic purposes remains unclear. The aim of this study was to report the expression of these receptors, based on immunohistochemistry. Cochrane Collaboration guidelines and PRISMA statements were followed. We did an online search in PubMed using the MeSH database. References were selected if the investigations occurred from 1990 to 2022. 61 references were included (34 descriptive observational studies, 26 analytical observational studies, and one case report). In this review, we describe the expression of these receptors in function of age, sex, hormonal context, localization, histological subtype, grade, and recurrence.

Advances in Molecular Biological and Translational Studies in World Health Organization Grades 2 and 3 Meningiomas: A Literature Review

The treatment of World Health Organization (WHO) grades 2 and 3 meningiomas remains difficult and controversial. The pathogenesis of high-grade meningiomas was expected to be elucidated to improve treatment strategies. The molecular biology of meningiomas has been clarified in recent years. High-grade meningiomas have been linked to NF2 mutations and 22q deletion. CDKN2A/B homozygous deletion and TERT promoter mutations are independent prognostic factors for WHO grade 3 meningiomas. In addition to 22q loss, 1p, 14p, and 9q loss have been linked to high-grade meningiomas. Meningiomas enriched in copy number alterations may be biologically invasive. Furthermore, several new comprehensive classifications of meningiomas have been proposed based on these molecular biological features, including DNA methylation status. The new classifications may have implications for treatment strategies for refractory aggressive meningiomas because they provide a more accurate prognosis compared to the conventional WHO classification. Although several systemic therapies, including molecular targeted therapies, may be effective in treating refractory aggressive meningiomas, these drugs are being tested. Systemic drug therapy for meningioma is expected to be developed in the future. Thus, this review aims to discuss the distinct genomic alterations observed in WHO grade 2 and 3 meningiomas, as well as their diagnostic and therapeutic implications and systemic drug therapies for high-grade meningiomas.

Progesterone Receptor Expression in Meningiomas: Pathological and Prognostic Implications

Background

The progesterone receptor (PR) is variably expressed in most meningiomas and was found to have prognostic significance. However, the correlation with patient age, tumor location, time to recurrence, and pattern of regrowth has scarcely been discussed.

Methods

A surgical series of 300 patients with meningiomas is reviewed. The PR expression was classified as: 0. absent; 1. low (<15%); 2. moderately low (16-50%); 3. moderately high (51-79%); 4. high (≥80%). The PR values were correlated with the patient age and sex, meningioma location, WHO grade, Ki-67 MIB1, recurrence rate, pattern of recurrence (local-peripheral versus multicentric diffuse), and time to recurrence.

Results

The PR expression has shown lower rate of high expression in the elderly group (p = 0.032) and no sex difference (including premenopausal versus postmenopausal women), higher expression in medial skull base and spinal versus other locations (p = 0.0036), inverse correlation with WHO grade and Ki67-MIB1 (p < 0.0001). Meningiomas which recurred showed at initial surgery higher rates of low or moderately low PR expression than the non-recurrent ones (p = 0.0004), whereas the pattern of regrowth was not significant. Higher rates of PR values ≥80% were found in cases with time to recurrence >5 years (p = 0.036).

Conclusion

The higher PR expression in medial skull base meningiomas, the significant correlation with the time to recurrence, the lack of difference of PR expression between premenopausal and postmenopausal women and between local-peripheral versus multicentric-diffuse recurrences are the most relevant unreported findings of this study. The rate of PR expression must be included in the routine pathological diagnosis of meningiomas because of its prognostic significance.

Role of ATP-Binding Cassette Transporter Proteins in CNS Tumors: Resistance- Based Perspectives and Clinical Updates

Despite gigantic advances in medical research and development, chemotherapeutic resistance remains a major challenge in complete remission of CNS tumors. The failure of complete eradication of CNS tumors has been correlated with the existence of several factors including overexpression of transporter proteins. To date, 49 ABC-transporter proteins (ABC-TPs) have been reported in humans, and the evidence of their strong association with chemotherapeutics' influx, dissemination, and efflux in CNS tumors, is growing. Research studies on CNS tumors are implicating ABC-TPs as diagnostic, prognostic and therapeutic biomarkers that may be utilised in preclinical and clinical studies. With the current advancements in cell biology, molecular analysis of genomic and transcriptomic interplay, and protein homology-based drug-transporters interaction, our research approaches are streamlining the roles of ABC-TPs in cancer and multidrug resistance. Potential inhibitors of ABC-TP for better clinical outcomes in CNS tumors have emerged. Elacridar has shown to enhance the chemo-sensitivity of Dasatanib and Imatinib in various glioma models. Tariquidar has improved the effectiveness of Temozolomide's in CNS tumors. Although these inhibitors have been effective in preclinical settings, their clinical outcomes have not been as significant in clinical trials. Thus, to have a better understanding of the molecular evaluations of ABC-TPs, as well as drug-interactions, further research is being pursued in research labs. Our lab aims to better comprehend the biological mechanisms involved in drug resistance and to explore novel strategies to increase the clinical effectiveness of anticancer chemotherapeutics, which will ultimately improve clinical outcomes.

Other Pituitary Conditions and Pregnancy

Diagnosis of lymphocytic hypophysitis occurring in the peripartum period is based on clinical and neuroradiological data and does not require a biopsy. Its course is generally spontaneously favorable in terms of mass effect but may require the administration of corticosteroids or even transsphenoidal resection. The course of pituitary deficiencies is highly variable; some cases recover over time, whereas others persist indefinitely. Sheehan syndrome is very rare in developed countries. Because agalactia and amenorrhea are often neglected, the diagnosis is generally delayed. Diabetes insipidus occurring in late pregnancy is caused by the increased placental production of vasopressinase and disappears after delivery.

Nonneuroendocrine Neoplasms of the Pituitary Region

CONTEXT

Although most sellar lesions are related to pituitary adenomas, the region gives rise to a variety of neoplasms that can be associated with substantial morbidity and/or mortality.

DESIGN

Information from reviews and guidelines of relevant societies dealing with such neoplasms, as well as articles that have provided new developments that made important contributions to their pathogenesis and treatment up to 2018, were obtained: public indexes such as PubMed/MEDLINE were used with the relevant search items.

RESULTS

Sellar neoplasms have a worse outcome than pituitary adenomas that is related not only to their natural history but also to side effects of therapies and evolving endocrine and/or hypothalamic deficiencies. Recent imaging advances have established the radiological fingerprint of some of these neoplasms, and several chromosomal aberrations have also been identified. Although established approaches along with new surgical and radiotherapeutic approaches remain the main treatment modalities, recent evidence has provided insight into their molecular pathogenesis involving, other than chemotherapy, treatments with targeted agents as in gliomas and craniopharyngiomas bearing BRAF mutations. Development of predictive markers of recurrences may also identify high-risk patients, including proliferative markers and expression of the progesterone receptor in meningiomas, and lead to less aggressive surgery. Owing to the rarity and complexity of these neoplasms, patients should be managed in dedicated centers.

CONCLUSIONS

The diagnosis and management of sellar neoplasms necessitate a multidisciplinary approach. Following evolving recent advances in their diagnosis and therapy, such a multidisciplinary approach needs to be extended to establish evidence-based diagnostic and management plans.

CHL1 suppresses tumor growth and metastasis in nasopharyngeal carcinoma by repressing PI3K/AKT signaling pathway via interaction with Integrin β1 and Merlin

Deletion of Chromosome 3p is one of the most frequently detected genetic alterations in nasopharyngeal carcinoma (NPC). We reported the role of a novel 3p26.3 tumor suppressor gene (TSG) CHL1 in NPC. Down-regulation of CHL1 was detected in 4/6 of NPC cell lines and 71/95 (74.7%) in clinical tissues. Ectopic expressions of CHL1 in NPC cells significantly inhibit colony formation and cell motility in functional study. By up-regulating epithelial markers and down-regulating mesenchymal markers CHL1 could induce mesenchymal-epithelial transition (MET), a key step in preventing tumor invasion and metastasis. CHL1 could also cause the inactivation of RhoA/Rac1/Cdc42 signaling pathway and inhibit the formation of stress fiber, lamellipodia, and filopodia. CHL1 could co-localize with adhesion molecule Integrin-β1, the expression of CHL1 was positively correlated with Integrin-β1 and another known tumor suppressor gene (TSG) Merlin. Down-regulation of Integrin-β1 or Merlin was significantly correlated with the poor survival rate of NPC patients. Further mechanistic studies showed that CHL1 could directly interact with integrin-β1 and link to Merlin, leading to the inactivation of integrin β1-AKT pathway. In conclusion, CHL1 is a vital tumor suppressor in the carcinogenesis of NPC.

Spontaneous regression of meningiomas after interruption of nomegestrol acetate: a series of three patients

BACKGROUND

The relationship between increased meningioma incidence and growth and long-term hormonal therapy with cyproterone acetate (CPA) in women has been recently established in literature. Following the raise in awareness from hormonal treatment, we describe a potential relationship between the progesterone agonist nomegestrol acetate (NOMAC) and meningioma growth.

METHODS

After implementation of a screening protocol to detect potential interactions between hormonal exposure and occurrence of meningioma, we identified patients taking NOMAC and newly diagnosed with a meningioma. NOMAC was stopped and those patients were followed tightly both clinically and radiologically. Retrospective volumetric analysis of the tumors was performed on the imaging.

RESULTS

Three patients were identified for the study. After cessation of the NOMAC, tumor shrinkage was documented for all meningiomas within the first month. Up to 70% of tumor volume reduction was observed during the first year of follow-up in one of them. None of the patients developed new symptoms.

CONCLUSION

We report the first cases of meningiomas responsiveness to discontinuation of hormonal therapy with NOMAC. Similarly to cases associated with long-term CPA intake, tumor reduction, and improvement of clinical symptoms can be observed after cessation of NOMAC.

[Use of the PELICAN software for the creation and export of standardized pathology reports in central nervous system tumors: Example of meningiomas]

INTRODUCTION

PELICAN ("Partager Efficacement en Laboratoire les Informations des Comptes rendus ANatomopathologiques") is a software, which generates standardized reports, and allows to automatically create a database. It has been used in central nervous system tumor pathology at the University Hospital of Nancy since 2014. The purpose of this article was to illustrate the use of this application for meningiomas, with a first statistical evaluation.

MATERIALS AND METHODS

The export of data included all cases of meningiomas recorded in the PELICAN application until July 2018. The PELICAN application is a Microsoft Excel file containing a software, written in Visual Basic for Applications, and used by the pathologist to create the report. The main clinical data were collected from the Hérault Register census form. Follow-up was systematically reported for atypical meningiomas.

RESULTS

Two hundred and ninety-five meningiomas were analyzed, including 250 grade I meningiomas, 42 grade II meningiomas, and 3 grade III meningiomas. Grade II meningiomas were characterized by a significantly higher proportion of men (P=0.002) and dural infiltration (P<0.001), a significant increase in the Ki-67 index (P<0.0001), and a significant decrease in progesterone receptor expression (P<0.001). In atypical meningiomas, a Ki-67 index of more than 20 % was significantly correlated with a shorter progression-free survival (P=0.032).

CONCLUSION

The PELICAN software is an easy-to-use tool that allows to generate standardized reports and feed a database, opening very interesting perspectives from an epidemiological and scientific point of view.

Relationships Between Neurofibromatosis-2, Progesterone Receptor Expression, the Use of Exogenous Progesterone, and Risk of Orbitocranial Meningioma in Females

Background: The pathogenesis of meningioma in females and its association with exogenous progesterone is remained unclear. This study was aimed to examine expression of Progesterone receptor (PR) and Neurofibromatosis-2 (NF2) and assess their relationships to history of exogenous progesterone use and risk of meningioma.

Methods: Our study was a case-control study that involves 115 females, 40 cases who diagnosed with orbito-cranial meningioma and 75 controls of healthy, that has been presented in previous study. The demographic characteristics, reproductive factors, and history of progesterone use were obtained in–depth face-to-face interviews. PR and NF2 mRNA were assessed by real-time quantitative polymerase chain reaction (RT-qPCR) on serum specimens.

Results: The mean age of participants in cases vs. controls were 46.6 ± 6.2 vs. 46.5 ± 7.45 (P = 0.969). The expression of PR and NF2 in cases was significantly lower than in controls. The longer duration of progesterone exposure was significantly associated with lower expression of PR and NF2. Significant association between lower expression of PR (OR 11.7; 95% CI 4.17–32.9; P < 0.001 comparing the lowest quartile vs. 3 highest quartile of PR) and NF2 (OR 4.23; 95% CI 1.85–9.67; P = 0.001 comparing the 2 lowest quartiles vs. 2 highest quartiles) with increased risk of meningioma were also reported.

Conclusion: In this study we showed that the longer the exposure to exogenous progesterone, the lower the expression of PR and NF2 mRNA in the serum. Low expression of PR and NF2 were associated with higher risk of meningioma, suggesting that low PR expression and inactivation of NF2 might play a key role in progesterone-associated meningioma tumorigenesis and may be potential clinical marker for females at higher risk of meningioma.

Molecular alterations in meningiomas: Literature review

Meningiomas, tumors that originate from meningothelial cells, account for approximately 30% of all new diagnoses of central nervous system neoplasms. According to the 2016 WHO classification of central nervous system tumors meningiomas are classified into three grades: I, II, and III. Past studies have shown that the risk of meningiomas recurrence is strongly correlated with the molecular profile of the tumor. Extensive whole-exome or whole-genome sequencing has provided a large body of information about the mutational landscape of meningiomas. However, such a stratification of meningiomas based on mutational analysis alone has been proven not to satisfy the clinical need for distinction between patients who need (or do not need) an adjuvant treatment. Combined analysis of exome, transcriptome, methylome and future approaches for epigenetic aspects in meningiomas may allow researchers to unveil a more comprehensive understanding of tumor progression mechanisms and, consequently, a more personalized clinical approach for patients with meningioma. A better understanding of the genetics and clinical behavior of high-grade meningiomas is mandatory in order to better design future clinical trials. By studying the mechanisms underlying these new tumorigenesis pathways, we should be able to offer personalized chemotherapy to patients with surgery and radiation-refractory meningiomas in the near future. The purpose of this article is to accurately bring the compilation of this information, for a greater understanding of the subject.

Expression of p40 (∆Np63) protein in meningiomas, an unexpected finding: immunohistochemical study and evaluation of its possible prognostic role

According to the 2007 WHO (World Health Organization) Classification, meningiomas are divided into three grades of malignancy, with different recurrence rate, based exclusively on histopathological parameters. Loss/reduction of PgR (Progesterone Receptor) expression and increased Ki67 L.I. (Labeling Index) have been proven as possible prognostic factors able to predict the relapse of the disease. However, they sometimes result unreliable, especially when discordant. p40 is the short form of the p53 homologue gene p63, also named ∆Np63, and its antibody has recently been introduced as a highly specific diagnostic marker of the squamous cell carcinoma of the lung. Nevertheless its expression has been found in many other unconventional sites (e.g. placenta, urotheluim, etc). Herein we assessed the immuno-expression of p40 protein in a series of 72 meningiomas (35 grade I and 37 grade II) and analyzed its correlation with clinicopathological parameters, overall survival and recurrence free interval. We found that a high p40 score correlated with high histological grade, presence of recurrence, increased Ki67 L.I. and loss/reduction of PgR signal. Moreover, a higher expression of p40 was shown to be a significant prognostic factor for the development of recurrences and resulted a prognostic independent variable in multivariate analysis. Overall, for the first time, we investigated the expression of p40 protein in meningiomas and explored its usefulness as prognostic marker in addition to PgR and Ki67 L.I.

Systemic therapy for recurrent meningioma

INTRODUCTION

Meningioma comprise 20-30% of all primary brain tumors. Notwithstanding surgery and radiotherapy, a subset of patients will manifest recurrent meningioma. Systemic therapy is recommended only when further surgery and radiotherapy are not possible. No prospective study with a high level of evidence is available to inform as to recommendations regarding systemic therapy.

AREAS COVERED

We aim to summarize systemic therapies for recurrent meningioma. Expert commentary: Hydroxurea, temozolomide, irinotecan, the combination of cyclophosphamide/adriamycine/vincristine, interferon-alpha, somatostatin analogs, mifepristone, megestrol acetate, imatinib, erlotinib and gefitinib are considered as having limited efficacy. Potential activity of VEGF (vascular endothelial growth factor) inhibitors such as sunitinib, valatinib, and bevacizumab is suggested in small non-controlled studies and requires validation in randomized trials. The identification of new prognostic markers such as TERT promoter mutations and potential new therapeutic targets, such as KLF4, AKT1, TRAF7, and SMO mutations hopefully facilitate this endeavor.

Biology and clinical management challenges in meningioma

Meningiomas are the most frequently occurring intracranial tumors. They are characterized by a broad spectrum of histopathologic appearance. Molecular alterations driving meningioma development, which affect the NF2 gene, are found in roughly 50% of patients. Rare genetic events in benign meningiomas are mutations in TRAF7, KLF4, AKT1, and SMO; all of these mutations are exclusive of NF2 alterations. Progression to a clinically aggressive meningioma is linked to inactivation of CDKN2A/B genes, and a plethora of signaling molecules have been described as activated in meningiomas, which supports the concept of successful clinical use of specific inhibitors. Established treatments include surgical resection with or without radiotherapy delivered in a single fraction, a few large fractions (radiosurgery), or multiple fractions (fractionated radiotherapy). For recurrent and aggressive tumors, inhibitors of the vascular endothelial growth factor (VEGF) pathway, such as vatalinib, bevacizumab, and sunitinib, showed signs of activity in small, uncontrolled studies, and prospective clinical studies will test the efficacy of the tetrahydroisoquinoline trabectedin and of SMO and AKT1 inhibitors.

Malignant progression to anaplastic meningioma: Neuropathology, molecular pathology, and experimental models

Meningioma is a common adult intracranial tumor, and while several cases are considered benign, a subset is malignant with biologically aggressive behavior and is refractory to current treatment strategies of combined surgery and radiotherapy. Anaplastic meningiomas are quite aggressive and correspond to a World Health Organization (WHO) Grade III tumor. This highly aggressive phenotype mandates the need for more efficacious therapies. Designing rational therapies for treatment will have its foundation in the biologic understanding of involved genes and molecular pathways in these types of tumors. Anaplastic meningiomas (WHO Grade III) can arise from malignant transformation of lower grade (WHO Grade I/II) tumors, however there is an incomplete understanding of specific genetic drivers of malignant transformation in these tumors. Here, the current understanding of anaplastic meningiomas is reviewed in the context of human neuropathologic specimens and small animal models.

Tumor suppressor role of protein 4.1B/DAL-1

Protein 4.1B/DAL-1 is a membrane skeletal protein that belongs to the protein 4.1 family. Protein 4.1B/DAL-1 is localized to sites of cell-cell contact and functions as an adapter protein, linking the plasma membrane to the cytoskeleton or associated cytoplasmic signaling effectors and facilitating their activities in various pathways. Protein 4.1B/DAL-1 is involved in various cytoskeleton-associated processes, such as cell motility and adhesion. Moreover, protein 4.1B/DAL-1 also plays a regulatory role in cell growth, differentiation, and the establishment of epithelial-like cell structures. Protein 4.1B/DAL-1 is normally expressed in multiple human tissues, but loss of its expression or prominent down-regulation of its expression is frequently observed in corresponding tumor tissues and tumor cell lines, suggesting that protein 4.1B/DAL-1 is involved in the molecular pathogenesis of these tumors and acts as a potential tumor suppressor. This review will focus on the structure of protein 4.1B/DAL-1, 4.1B/DAL-1-interacting molecules, 4.1B/DAL-1 inactivation and tumor progression, and anti-tumor activity of the 4.1B/DAL-1.

The Protein 4.1 family: hub proteins in animals for organizing membrane proteins

Proteins of the 4.1 family are characteristic of eumetazoan organisms. Invertebrates contain single 4.1 genes and the Drosophila model suggests that 4.1 is essential for animal life. Vertebrates have four paralogues, known as 4.1R, 4.1N, 4.1G and 4.1B, which are additionally duplicated in the ray-finned fish. Protein 4.1R was the first to be discovered: it is a major mammalian erythrocyte cytoskeletal protein, essential to the mechanochemical properties of red cell membranes because it promotes the interaction between spectrin and actin in the membrane cytoskeleton. 4.1R also binds certain phospholipids and is required for the stable cell surface accumulation of a number of erythrocyte transmembrane proteins that span multiple functional classes; these include cell adhesion molecules, transporters and a chemokine receptor. The vertebrate 4.1 proteins are expressed in most tissues, and they are required for the correct cell surface accumulation of a very wide variety of membrane proteins including G-Protein coupled receptors, voltage-gated and ligand-gated channels, as well as the classes identified in erythrocytes. Indeed, such large numbers of protein interactions have been mapped for mammalian 4.1 proteins, most especially 4.1R, that it appears that they can act as hubs for membrane protein organization. The range of critical interactions of 4.1 proteins is reflected in disease relationships that include hereditary anaemias, tumour suppression, control of heartbeat and nervous system function. The 4.1 proteins are defined by their domain structure: apart from the spectrin/actin-binding domain they have FERM and FERM-adjacent domains and a unique C-terminal domain. Both the FERM and C-terminal domains can bind transmembrane proteins, thus they have the potential to be cross-linkers for membrane proteins. The activity of the FERM domain is subject to multiple modes of regulation via binding of regulatory ligands, phosphorylation of the FERM associated domain and differential mRNA splicing. Finally, the spectrum of interactions of the 4.1 proteins overlaps with that of another membrane-cytoskeleton linker, ankyrin. Both ankyrin and 4.1 link to the actin cytoskeleton via spectrin, and we hypothesize that differential regulation of 4.1 proteins and ankyrins allows highly selective control of cell surface protein accumulation and, hence, function. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé

Novel therapies for meningiomas

Although advances in surgery, radiation therapy and stereotactic radiosurgery have significantly improved the treatment of meningiomas, there remains an important subset of patients who remain refractory to conventional therapy. Treatment with chemotherapeutic agents such as hydroxyurea and alpha-interferon has provided minimal benefit. In this review, the role of newly emerging novel therapies for meningiomas, with a focus on targeted molecular agents, will be discussed.

Diagnostic and molecular pathology of meningiomas

This article will review the neuropathology of meningiomas. From the neurosurgeon's point of view, accurate neuropathological diagnosis will play an increasingly important role in clinical practice. Predicting an individual patient's prognosis will become ever more important with the advent of various new radiotherapeutic/radiosurgical modalities. Defining the optimal treatment for nonbenign meningiomas requires a robust and reproducible diagnosis. This review will therefore not only describe classical radiological and histopathological diagnosis, but will also focus on the emerging field of molecular neuropathology. Implementing these advances in our daily clinical routine holds the promise of improving diagnostic accuracy.

Biological and demographic profile of meningiomas in a cohort of Egyptian patients: impact on tumor recurrence

Objective. This work was designed to study the biological and demographic characteristics of meningiomas and their impact on tumor recurrence in Egyptian patients. Material and Methods. A cohort of 265 Egyptian patients with meningioma was studied. Immunohistochemistry for VEGF, Ki67, PR, CD20, and CD3 was performed. Statistical analysis was used to detect independent predictors of recurrence. Results. Adults represented 98.9% of cases, with female preponderance (M : F ratio = 1 : 2.4). Histologically, 78.10% of cases were grade I, 19.20% were grade II, and 2.60% were grade III. Transitional variant was the most common (43.40%). VEGF expression (38.50% of cases) correlated positively with perifocal edema, tumor size, and proliferative index (PI). PR expression (64.5% of cases) correlated inversely with the PI (mean 3.75). Lymphocytic aggregates were detected in 7.20% of cases, with a mean CD20 : CD3 ratio of 1 : 10.1. In a multivariate analysis, only tumor size, PR expression and necrosis predicted recurrence independently. Using ROC curve, size was the best predictor of tumor recurrence with a cut-off point of >6 cm and an excellent negative predictive value (97.6%). Conclusions. Meningiomas in our region showed some distinctive clinicopathological and demographic criteria. Tumor size was found to be the best recurrence predictor factor of meningioma.

Recent developments in chemotherapy for meningiomas: a review

Object

Currently, few medical options exist for refractory and atypical/anaplastic meningiomas. New developments in chemotherapeutic options for meningiomas have been explored over the past decade. The authors review these recent developments, with an emphasis on emerging avenues for therapy, clinical efficacy, and adverse effects.

Methods

A review of the literature was performed to identify any studies exploring recent medical and chemotherapeutic agents that have been or are currently being tested for meningiomas. Results from included preclinical and human clinical trials were reviewed and summarized.

Results

Current guidelines recommend only 3 drugs that can be used to treat patients with refractory and highgrade meningiomas: hydroxyurea, interferon-α 2B, and Sandostatin long-acting release. Recent developments in the medical treatment of meningiomas have been made across a variety of pharmacological classes, including cytotoxic agents, hormonal agents, immunomodulators, and targeted agents toward a variety of growth factors and their signaling cascades. Promising avenues of therapy that are being evaluated for efficacy and safety include antagonists of platelet-derived growth factor receptor, epidermal growth factor receptor, vascular endothelial growth factor receptor, and mammalian target of rapamycin. Because malignant transformation in meningiomas is likely to be mediated by numerous processes interacting via a complex matrix of signals, combination therapies affecting multiple molecular targets are currently being explored and hold significant promise as adjuvant therapy options.

Conclusions

Improved understanding of the molecular mechanisms driving meningioma tumorigenesis and malignant transformation has resulted in the targeted development of more specific agents for chemotherapeutic intervention in patients with nonresectable, aggressive, and malignant meningiomas.

Meningiomas in pregnancy: a clinicopathologic study of 17 cases

BACKGROUND

Dramatic growth of meningiomas is occasionally encountered during pregnancy. While cell proliferation is often assumed, hemodynamic changes have also been touted as a cause.

OBJECTIVE

We identified 17 meningiomas resected during pregnancy or within 3 weeks post-partum and characterized them to determine the cause of occasional rapid growth in pregnancy.

METHODS

Seventeen tumors were identified from searches at 4 university centers. All available clinical records, radiology images, and tissue specimens were reviewed, with immunohistochemical studies performed as needed.

RESULTS

Sixteen patients underwent tumor resection and 1 died of complications prior to surgery. Average patient age was 32 years. Nine experienced onset of symptoms in the third trimester or within 8 days post-partum. Principle physical findings included visual complaints (59%) and cranial nerve palsies (29%). Ten tumors (59%) were located in the skull base region. The Ki-67 labeling index was low (0.5-3.6%) in 11 of 13 benign (grade I) tumors and elevated (11-23.2%) in 3 of 4 atypical (grade II) meningiomas. Eight (50%) tumors featured hypervascularity with at least focal CD34-positive hemangioma-like microvasculature. Fourteen (82%) showed evidence of intra- and/or extracellular edema, 1 so extensive that its meningothelial nature was not apparent. Five tumors (29%) exhibited intratumoral hemorrhage and/or necrosis.

CONCLUSION

Our series suggests that pregnancy-associated meningiomas located in the skull base are likely to require surgical intervention for visual complaints and cranial nerve palsies. The rapid tumor growth is more often due to potentially reversible hemodynamic changes rather than hormone-induced cellular proliferation.

Loss of expression of the differentially expressed in adenocarcinoma of the lung (DAL-1) protein is associated with metastasis of non-small cell lung carcinoma cells

The differentially expressed in adenocarcinoma of the lung-1 (DAL-1) protein is a member of the membrane-associated cytoskeleton protein 4.1 family. This protein was previously found to be downregulated or lost in more than half of primary non-small cell lung cancers (NSCLC). In this study, the relationship between DAL-1 expression and NSCLC metastasis was examined. DAL-1 mRNA and protein levels were measured in NSCLC cell lines and in tumor cells isolated from the pleural fluid of NSCLC patients clinically diagnosed with distant metastases to the bone or brain. The results revealed that DAL-1 expression was observed in two (GLC-82 and NCI-H460) out of seven metastatic NSCLC cell lines examined. DAL-1 expression was not observed in the cells isolated from the pleural fluid in nine out of ten patients. Overexpression of DAL-1 in A549 cells, a cell line lacking endogenous DAL-1, inhibited cell migration and invasion by approximately 38 and 48 %, respectively. In contrast, DAL-1 knockdown in NCI-H460 cells enhanced the migration and invasion potential of this cell line 4.6- and 3-fold, respectively. Furthermore, DAL-1 promoter methylation was observed in six of nine pleural fluid NSCLC cell isolates and in two cell lines (A549 and H1299), as evidenced by a lack of endogenous DAL-1. Demethylation in A549 cells successfully restored DAL-1 mRNA and protein expression levels, resulting in a parallel remarkable inhibition of migration and invasion. These results indicated that DAL-1 was pivotal in triggering NSCLC migration and invasion and that loss of DAL-1 expression was due to the epigenetic methylation.

Fatty acid synthase is a predictive marker for aggressiveness in meningiomas

Meningiomas are the most frequent intracranial tumors. Although most are benign WHO grade I tumors, grade II and III tumors are aggressive and survival is poor. Treatment options for grade II and III meningiomas are limited, and molecular targets are few. The re-programming of metabolic pathways including glycolysis, lipogenesis, and nucleotide synthesis is a hallmark of the physiological changes in cancer cells. Because fatty acid synthase (FAS), the enzyme responsible for the de-novo synthesis of fatty acids, has emerged as a potential therapeutic target for several cancers, we investigated its involvement in meningiomas. We subjected 92 paraffin-embedded samples from 57 patients with grade I, 18 with grade II and III, and six with radiation-induced tumors to immunohistochemical study of FAS. Whereas its expression was increased in grade II and III meningiomas (62.9 %) compared with grade I tumors (29.8 %) (chi-squared test: p < 0.001), FAS was expressed in grade I tumors with a high MIB-1 index and infiltration into surrounded tissues. All radiation-induced meningiomas expressed FAS and its expression was positively correlated with the MIB-1 index (p < 0.005). Our findings suggest that increased FAS expression reflects the aggressiveness of meningiomas and that it may be a novel therapeutic target for treatment of unresectable or malignant tumors.

Correlation of p63 Protein Expression With Histological Grade of Meningiomas

Prediction of tumor behavior in meningiomas based on morphological features alone remains difficult. Several immunohistochemical biomarkers have been proposed to assist conventional methods. However, no single immunohistochemical marker can unequivocally discriminate between benign and aggressive meningiomas. There is only 1 study available in the literature that correlates p63 expression with overall histological grade of the meningioma. The present study is undertaken to assess the correlation between p63 expression and histological grade of meningiomas. For this purpose, the authors studied and analyzed the immunohistochemical expression of p63 in 85 cases of meningioma, including WHO grade I (63), grade II (11), and grade III (11) cases. Correlation between histological grade and nuclear immunoreactivity to p63 antibody was performed. Furthermore, expression of p63 protein was correlated with short clinical follow-up and Ki-67 proliferation index. Among 85 patients analyzed, there were 61 women (71.7 %) and 24 men (28.2%) between 7 and 75 years old. Expression of p63 protein was found in 34.9% of grade I cases, but in grade II and III, 63.6% of cases each were immunoreactive. Correlation between histological grade and p63 immunoreactivity was significant ( P = .02). p63-positive grade I meningiomas did not show elevated Ki-67 index. The present study contradicts earlier reports because there are a considerable number of grade I meningiomas that express p63. Although p63 expression is significantly associated with higher histological grade of meningiomas, it may not be considered as a sole biomarker to assess aggressive behavior of the tumor.

Mild cognitive impairment: pathology and mechanisms

Mild cognitive impairment (MCI) is rapidly becoming one of the most common clinical manifestations affecting the elderly. The pathologic and molecular substrate of people diagnosed with MCI is not well established. Since MCI is a human specific disorder and neither the clinical nor the neuropathological course appears to follow a direct linear path, it is imperative to characterize neuropathology changes in the brains of people who came to autopsy with a well-characterized clinical diagnosis of MCI. Herein, we discuss findings derived from clinical pathologic studies of autopsy cases who died with a clinical diagnosis of MCI. The heterogeneity of clinical MCI imparts significant challenges to any review of this subject. The pathologic substrate of MCI is equally complex and must take into account not only conventional plaque and tangle pathology but also a wide range of cellular, biochemical and molecular deficits, many of which relate to cognitive decline as well as compensatory responses to the progressive disease process. The multifaceted nature of the neuronal disconnection syndrome associated with MCI suggests that there is no single event which precipitates this prodromal stage of AD. In fact, it can be argued that neuronal degeneration initiated at different levels of the central nervous system drives cognitive decline as a final common pathway at this stage of the dementing disease process.

Evolution and future of skull base surgery: the paradigm of skull base meningiomas

BACKGROUND

Skull base meningiomas represent the paradigm for the evolution of skull base surgery within the past 50 years into a distinct neurosurgical subspecialty.

METHODS

From 2005 to 2011, 117 patients with cranial base meningiomas underwent surgical resection. Extent of resection, histologic grade, complications, functional status, and recurrence-free and overall survival data are presented.

RESULTS

The summary rate of gross total resection was 53.0%. The surgical complication and mortality rates were 17.9% and 0.9%, respectively. Five-year recurrence-free survival was 88.0% for grade I meningiomas. A total of 90.3% of patients had a Karnofsky performance score ≥ 80 at last follow-up.

CONCLUSIONS

A large contemporary series of skull base meningiomas is presented. In addition, the evolution of surgical approaches to skull base meningiomas is reviewed, together with the current issues regarding radiation therapy, management of cavernous sinus tumor, oncologic management of atypical and malignant subtypes, molecular genetics, and future therapeutic options.

Update on meningiomas

Although meningiomas are the most common tumor in the central nervous system, their incidence, epidemiology, and clinical outcomes have historically been poorly defined. This has been attributed to their benign course, difficulty obtaining histologic diagnosis, and lack of uniform database registration. Their clinical behavior can range from a silent incidentaloma to a lethal tumor. Projections of an aging population should raise medical awareness of an expectant rise in the incidence of meningiomas. This disease increases with advancing age, has a female predilection, and exposure to ionizing radiation is associated with a higher risk for disease development. There have been minimal advances in treatment, except in radiation therapy. Although no U.S. Food and Drug Administration-approved systemic therapy exists, there are treatment options that include hydroxyurea and sandostatin. Currently, no molecularly targeted therapy has provided clinical benefit, although recurring molecular alterations are present and novel therapies are being investigated.

Wilms tumor-1, claudin-1 and ezrin are useful immunohistochemical markers that help to distinguish schwannoma from fibroblastic meningioma

The aim of this study is to identify immunohistochemical (IHC) markers that can reliably separate schwannoma (SCHW) and fibroblastic meningioma (FM). We selected 106 cases of intracranial SCHW (n = 56) and FM (n = 50) and constructed a tissue microarray (TMA) of core diameter of 1.0 mm from archival formalin-fixed paraffin-embedded tissue. A TMA-IHC was performed using 14 antibodies. After IHC staining, 98 cores were found suitable for evaluation. The IHC staining was scored as 0-2+ (0, negative; 1+, weak and/or focal 2+ strong and/or diffuse positive). A discriminant analysis (DA) (Wilks'Lambda test) was performed to assess the relative importance of these biomarkers in classifying the two groups FM and SCHW. It showed that WT-1 (Wilks'λ 0.085, p < 0.001), EMA (Wilks'λ 0.253, p < 0.001), S100 (Wilks'λ 0.487, p < 0.001), Claudin-1 (Wilks' λ 0.57, p < 0.001) and Ezrin (Wilks'λ 0.656, p < 0.001), SPARC (Wilks'λ 0.751, p < 0.01), NP-Y (Wilks'λ, 0.819, p < 0.001) and EGFR (Wilks'λ 0.845, p = 0.026) were some of the statistically significant markers that discriminated SCHW and FM. For sensitivity and specificity for SCHW the significant markers [Area under the curve (95% CI), p-value] by ROC analysis were WT-1 [0.990(0.000, 1.000), <0.001], S100 [0.880(0.808, 0.951), <0.001] while for diagnosing FM the most sensitive and specific markers were EMA [0.957(0.914, 1.000), <. 001], Claudin-1 [0.857(0.782, 0.932), <0.001] and ezrin [0.792(0.700,0.884),<0.001]. WT-1, Claudin-1 and Ezrin may be potentially useful immunohistochemical adjuncts to EMA and S100 that differentiate SCHW from FM.

Molecular biology of unreresectable meningiomas: implications for new treatments and review of the literature

Even though meningiomas are most often benign tumors, they can be locally invasive and can develop in locations that prevent surgical treatment. The molecular and biologic factors underlying meningioma development are only now beginning to be understood. Genetic factors such as mutations in the neurofibromatosis-2 gene and in chromosomes 1, 9, and 10 play important roles in meningioma development and may be responsible for atypical tumors in some cases. Cellular factors such as telomerase activation and tyrosine kinase receptor mutations may also play an important role. Finally, autocrine and paracrine factors including epidermal growth factor receptor, platelet-derived growth factor-1, and fibroblast growth factor have been implicated in the development of some tumors. Although the relationship between the various factors implicated in tumor development is unknown, understanding these factors will be critical in the treatment of malignant or surgically inaccessible tumors.

The molecular genetics and tumor pathogenesis of meningiomas and the future directions of meningioma treatments

Meningiomas are mostly benign, slow-growing tumors of the CNS that originate from arachnoidal cap cells. While monosomy 22 is the most frequent genetic abnormality found in meningiomas, a multitude of other aberrant chromosomal alterations, signaling pathways, and growth factors have been implicated in its pathogenesis. Losses on 22q12.2, a region encoding the tumor suppressor gene merlin, represent the most common genetic alterations in early meningioma formation. Malignant meningioma progression, however, is associated with more complex karyotypes and greater genetic instability. Cytogenetic studies of atypical and anaplastic meningiomas revealed gains and losses on chromosomes 9, 10, 14, and 18, with amplifications on chromosome 17. However, the specific gene targets in a majority of these chromosomal abnormalities remain elusive.

Studies have also implicated a myriad of aberrant signaling pathways involved with meningioma tumorigenesis, including those involved with proliferation, angiogenesis, and autocrine loops. Understanding these disrupted pathways will aid in deciphering the relationship between various genetic changes and their downstream effects on meningioma pathogenesis.

Despite advancements in our understanding of meningioma pathogenesis, the conventional treatments, including surgery, radiotherapy, and stereotactic radiosurgery, have remained largely stagnant. Surgery and radiation therapy are curative in the majority of lesions, yet treatment remains challenging for meningiomas that are recurrent, aggressive, or refractory to conventional treatments. Future therapies will include combinations of targeted molecular agents as a result of continued progress in the understanding of genetic and biological changes associated with meningiomas.

Comparative protein profiling reveals minichromosome maintenance (MCM) proteins as novel potential tumor markers for meningiomas

Meningiomas are among the most frequent tumors of the brain and spinal cord accounting for 15-20% of all central nervous system tumors and frequently associated with neurofibromatosis type 2. In this study, we aimed to unravel molecular meningioma tumorigenesis and discover novel protein biomarkers for diagnostic and/or prognostic purposes and performed in-depth proteomic profiling of meningioma cells compared to human primary arachnoidal cells. We isolated proteins from meningioma cell line SF4433 and human primary arachnoidal cells and analyzed the protein profiles by Gel-nanoLC-MS/MS in conjunction with protein identification and quantification by shotgun nanoLC tandem mass spectrometry and spectral counting. Differential analysis of meningiomas revealed changes in the expression levels of 281 proteins (P < 0.01) associated with various biological functions such as DNA replication, recombination, cell cycle, and apoptosis. Among several interesting proteins, we focused on a subset of the highly significantly up-regulated proteins, the minichromosome maintenance (MCM) family. We performed subsequent validation studies by qRT-PCR in human meningioma tissue samples (WHO grade I, 14 samples; WHO grade II, 7 samples; and WHO grade III, 7 samples) compared to arachnoidal tissue controls (from fresh autopsies; 3 samples) and found that MCMs are highly and significantly up-regulated in human meningioma tumor samples compared to arachnoidal tissue controls. We found a significant increase in MCM2 (8 fold), MCM3 (5 fold), MCM4 (4 fold), MCM5 (4 fold), MCM6 (3 fold), and MCM7 (5 fold) expressions in meningiomas. This study suggests that MCM family proteins are up-regulated in meningiomas and can be used as diagnostic markers.

Fatty acid synthase as a novel target for meningioma therapy

High levels of fatty acid synthase (FAS) expression have been reported in hormone receptor-positive tumors, including prostate, breast, and ovarian cancers, and its inhibition reduces tumor growth in vitro and in vivo. Similar to other hormone receptor-positive tumor types, meningiomas are progesterone receptor- and estrogen receptor-immunoreactive brain tumors. To define the role of FAS in human meningioma growth control, we first analyzed the FAS expression using a tissue microarray containing 38 meningiomas and showed increased FAS expression in 70% of atypical WHO grade II and anaplastic WHO grade III meningiomas compared with 10% of benign WHO grade I tumors. We next confirmed this finding by real-time PCR and Western blotting. Second, we demonstrated that treatment with the FAS inhibitor, cerulenin (Cer), significantly decreased meningioma cell survival in vitro. Third, we showed that Cer treatment reduced FAS expression by modulating Akt phosphorylation (activation). Fourth, we demonstrated that Cer treatment of mice bearing meningioma xenografts resulted in significantly reduced tumor volumes associated with increased meningioma cell death. Collectively, our data suggest that the increased FAS expression in human meningiomas represents a novel therapeutic target for the treatment of unresectable or malignant meningioma.

Expression of the Tumor Suppressor Genes NF2, 4.1B, and TSLC1 in Canine Meningiomas

Meningiomas are common primary brain tumors in dogs; however, little is known about the molecular genetic mechanisms involved in their tumorigenesis. Several tumor suppressor genes have been implicated in meningioma pathogenesis in humans, including the neurofibromatosis 2 ( NF2), protein 4.1B ( 4.1 B), and tumor suppressor in lung cancer-1 ( TSLC1) genes. We investigated the expression of these tumor suppressor genes in a series of spontaneous canine meningiomas using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) ( NF2; n = 25) and western blotting (NF2/merlin, 4.1B, TSLC1; n = 30). Decreased expression of 4.1B and TSLC1 expression on western blotting was seen in 6/30 (20%) and in 15/30 (50%) tumors, respectively, with 18/30 (60%) of meningiomas having decreased or absent expression of one or both proteins. NF2 gene expression assessed by western blotting and RT-PCR varied considerably between individual tumors. Complete loss of NF2 protein on western blotting was not seen, unlike 4.1B and TSLC1. Incidence of TSLC1 abnormalities was similar to that seen in human meningiomas, while perturbation of NF2 and 4.1B appeared to be less common than reported for human tumors. No association was observed between tumor grade, subtype, or location and tumor suppressor gene expression based on western blot or RT-PCR. These results suggest that loss of these tumor suppressor genes is a frequent occurrence in canine meningiomas and may be an early event in tumorigenesis in some cases. In addition, it is likely that other, as yet unidentified, genes play an important role in canine meningioma formation and growth.

Aggressive pediatric meningioma with soft tissue and lymph node metastases: a case report

Metastatic meningioma is extremely rare, occurring in an estimated 0.1% of cases. We report a case of pediatric meningioma metastatic to cervical soft tissue and lymph nodes. An 8-year-old boy presented with headaches, dizziness, and involuntary eye flickering. Magnetic resonance imaging (MRI) revealed a 7.5-cm parasagittal, dural-based mass with venous sinus encasement. Therapeutic embolization was followed by bilateral craniotomy, achieving subtotal resection. Histopathologic examination revealed an atypical meningioma with regions of hypercellularity, small cell morphology, sheeting architecture, increased mitoses, and brain invasion. Surveillance MRI studies showed growth of residual tumor and enlarging cervical soft tissue masses with posterior triangle lymphadenopathy. Radiation and surgical resection were employed for the intracranial tumor burden; resection of the soft tissue masses revealed metastatic meningioma, with soft tissue infiltration and metastasis to 8 lymph nodes. This case demonstrates the aggressive biologic potential of pediatric meningiomas, with potential for distant spread via cerebrospinal fluid leakage and lymphatic invasion.