Association of loss of 1p and alterations of chromosome 14 in meningioma progression

Molecular landscapes of longitudinal NF2/22q and non-NF2/22q meningiomas show different life histories

Recurrence is a major complication of some meningiomas. Although there were many studies on biomarkers associated with higher grades or increased aggressiveness, few studies specifically examined longitudinal samples of primary meningiomas and recurrences from the same patients for molecular life history. We studied 99 primary and recurrent meningiomas from 42 patients by FISH for 22q, 1q, 1p, 3p, 5q, 6q, 10p, 10q, 14q, 18q, CDKN2A/B homozygous deletion, ALT (Alternative Lengthening of Telomere), TERT re-arrangement, targeted sequencing and TERTp sequencing. Although NF2 mutation and 22q were well known to be aetiological events in meningiomas, we found that in these paired meningiomas, combining the two events resulted in an NF2/22q group (57 tumors from 25 patients) which were almost mutually exclusive with those cases without these two changes (42 tumors from 17 patients) for NF2/22q. No other molecular changes were totally unique to NF2/22q or non-NF2/22q tumors. For molecular evolution, NF2/22q meningiomas had higher cytogenetic abnormalities than non-NF2/22q meningiomas (p = 0.003). Most of the cytogenetic changes in NF2/22q meningiomas were present from the outset whereas for non-NF2/22q meningiomas, cytogenetic events were uncommon in the primary tumors and most were acquired in recurrences. For non-NF2/22q tumors, CDKN2A/B homozygous deletion, 1q gain, 18p loss, 3p loss, and ALT were preferentially found in recurrences. Mutations were largely conserved between primary and recurrent tumors. Phylogenetic trees showed 11/11 patients with multiple recurrent tumors had a conserved evolutionary pattern. We conclude that for molecular life history, NF2 and 22q should be regarded as a group. NF2/22q recurring meningiomas showed more cytogenetic abnormalities in the primary tumors, whereas non-NF2/22q meningiomas showed CDKN2A/B deletion and other cytogenetic abnormalities and ALT at recurrences. Although chromosome 1p loss is a known poor prognostic marker in meningiomas, it was also associated with a shorter TBR (time between resection) in this cohort (p = 0.002).

Molecular diagnosis and treatment of meningiomas: an expert consensus (2022)

ABSTRACT

Meningiomas are the most common primary intracranial neoplasm with diverse pathological types and complicated clinical manifestations. The fifth edition of the WHO Classification of Tumors of the Central Nervous System (WHO CNS5), published in 2021, introduces major changes that advance the role of molecular diagnostics in meningiomas. To follow the revision of WHO CNS5, this expert consensus statement was formed jointly by the Group of Neuro-Oncology, Society of Neurosurgery, Chinese Medical Association together with neuropathologists and evidence-based experts. The consensus provides reference points to integrate key biomarkers into stratification and clinical decision making for meningioma patients.

REGISTRATION

Practice guideline REgistration for transPAREncy (PREPARE), IPGRP-2022CN234.

Matched Paired Primary and Recurrent Meningiomas Points to Cell-Death Program Contributions to Genomic and Epigenomic Instability along Tumor Progression

Meningioma (MN) is an important cause of disability, and predictive tools for estimating the risk of recurrence are still scarce. The need for objective and cost-effective techniques addressed to this purpose is well known. In this study, we present methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) as a friendly method for deepening the understanding of the mechanisms underlying meningioma progression. A large follow-up allowed us to obtain 50 samples, which included the primary tumor of 20 patients in which half of them are suffering one recurrence and the other half are suffering more than one. We histologically characterized the samples and performed MS-MLPA assays validated by FISH to assess their copy number alterations (CNA) and epigenetic status. Interestingly, we determined the increase in tumor instability with higher values of CNA during the progression accompanied by an increase in epigenetic damage. We also found a loss of HIC1 and the hypermethylation of CDKN2B and PTEN as independent prognostic markers. Comparison between grade 1 and higher primary MN's self-evolution pointed to a central role of GSTP1 in the first stages of the disease. Finally, a high rate of alterations in genes that are related to apoptosis and autophagy, such as DAPK1, PARK2, BCL2, FHIT, or VHL, underlines an important influence on cell-death programs through different pathways.

Emerging glioneuronal and neuronal tumors: case-based review

Glioneuronal and neuronal tumors (GNTs) are rare heterogeneous central nervous system tumors characterized by slow growth and favorable outcomes, but are often associated with diagnostic difficulties. A thorough analysis of three rare and recently recognized GNTs was performed in the context of clinicopathological features and molecular genetic characterization. The current spinal diffuse leptomeningeal glioneuronal tumor (DLGNT) was characterized with oligodendroglioma-like tumor with chromosome 1p/19q codeletion without IDH mutations and KIAA1549:BRAF fusion. The current occipital multinodular and vacuolating neuronal tumor (MVNT) was characteristic of the variable-sized vague nodules consisted of gangliocytic tumor cells with intracytoplasmic and pericellular vacuolation and the next-generation sequencing (NGS) revealed MAP2K1 p.Q56_V60del. A diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) of the amygdala was characterized by oligodendroglia-like cells and nuclear clusters, and monosomy 14. From the current cases and literature review, we found that DLGNT commonly occurs in the spinal cord and can make mass and more commonly have KIAA1549:BRAF fusion; MVNT is a neoplasm rather than malformation and MAP2K1 deletion is one of the hallmarks of this tumor; although DGONC may require a methylation profile, we can reach a diagnosis through its unique histology, monosomy 14, and exclusion diagnosis without a methylation profile.

The 2016 Edition of the WHO Classification of Primary Brain Tumors: Applicable to Assess Individual Risk of Recurrence in Atypical Meningioma? A Single-Center Experience

BACKGROUND AND STUDY AIMS/OBJECT

 Despite the relevance of molecular criteria for brain tumor diagnosis and prognosis, meningioma grading is still solely based on histologic features. Atypical meningiomas (AMs; WHO grade II) display a great histologic heterogeneity and individual courses of disease can differ significantly. This study aimed to identify clinically aggressive AMs that are prone to early recurrence after gross total resection (GTR) by assessing a specific histologic score.

PATIENTS AND METHODS

 A retrospective analysis of 28 consecutive patients (17 females and 11 males; mean age of 62 years [range: 35-88 years]) treated in our institution between January 2006 and December 2015 was performed. Basic demographic and clinical characteristics were assessed. A scoring scale was designed to address the histologic diversity by summing up the individual histologic features in every tumor sample. According to that, points were awarded as follows: major AM defining criterion (3 points) and minor criterion (1 point).

RESULTS

 The subclassification based on our specific histologic score revealed no significant difference in frequency of one (46.4%) or two (42.9%) AM defining features; three criteria were less frequently seen (10.7%). Mean follow-up was 61.89 ± 9.03 months. Local recurrence occurred in 35.7% after a mean time of 37.4 ± 22.6 months after primary surgery. Age > 60 years was significantly associated with a shorter progression-free survival (PFS). There was a trend toward shorter PFS with increasing scores, tantamount with the presence of several AM defining histologic criteria in one sample. No tumor relapse was seen when diagnosis was based only on minor criteria.

CONCLUSION

 AMs display a histologic diversity. There is a trend toward shorter PFS with increasing numbers of AM defining histologic features. The inclusion of this score in the decision algorithm regarding further treatment for patients >60 years after GTR might be helpful and should be evaluated in further studies.

Everolimus and Bevacizumab in the Management of Recurrent, Progressive Intracranial NF2 Mutated Meningioma

Meningiomas are primary CNS tumors that arise from the arachnoid layer of the meninges. Genomic sequencing has revealed that NF2 mutations are the most common genetic alteration seen in meningiomas. Meningiomas although usually low grade, can sometimes progress to high grade. A patient who had several recurrences of meningiomas since childhood presented with recurrent headaches. Imaging showed that he had another recurrence of a meningioma. He underwent surgery for resection of the meningioma and histopathology showed NF2 mutation. He was started on everolimus and bevacizumab with good effect. Studies have shown that NF-2 mutated meningiomas have a good response to everolimus and bevacizumab with increased progression-free survival time and progression-free survival time at 6 months.

TERT promoter mutation is associated with worse prognosis in WHO grade II and III meningiomas

INTRODUCTION

Transcriptional activating mutations in the promoter region of the telomerase reverse transcriptase (TERT) gene occur at high frequency in various types of solid tumors and have also been reported for meningiomas. Especially for atypical and anaplastic meningiomas, the prognostic relevance of TERT promoter mutation is yet unclear. The present study aimed to analyze the frequency of TERT promoter mutation and define its long-term prognostic significance beyond clinical and histological factors in a cohort of meningiomas WHO grade II and III.

METHODS

Patients undergoing surgical resection of aggressive meningiomas were included. Analysis for C228T and C250T mutation in the TERT promoter region was performed using PCR method. Patients were stratified into two groups (TERT mutated vs. TERT wild type). Univariate analysis was conducted using molecular and histological factors.

RESULTS

87 patients with atypical (N = 72) and anaplastic meningiomas (N = 15) were included in the study. TERT promoter region was found to be mutated in 4 WHO grade II and 2 WHO grade III meningiomas. TERT promoter mutation was associated with shorter progression free survival than TERT wild type meningiomas (median PFS 12.5 vs. 26 months, p = .004). In the univariate analysis, TERT promoter mutation had a strong prognostic value on overall survival (p = .009) and progression free survival.

CONCLUSIONS

Presence of TERT promoter mutation is associated with shorter progression free survival and overall survival in meningiomas WHO grade II and III. In these tumors, TERT promoter mutation should be considered as a clinically relevant prognostic factor to identify high risk patients.

Molecular progression in unusual recurrent non-pediatric intracranial clear cell meningioma

We report a case of a recurrent clear cell meningioma (ccm) in the frontal lobe of the brain of a 67-year-old man. The patient developed three recurrences: at 3, 10, and 12 years after his initial surgery. Histopathology observations revealed a grade 2 ccm with positivity for vimentin and epithelial membrane antigen. Expression of E-cadherin was positive only in the primary tumour and in the first available recurrence. Fluorescence in situ hybridization analyses demonstrated 1p and 14q deletions within the last recurrence. Multiplex ligation-dependent probe amplification studies revealed a heterozygous partial NF2 gene deletion, which progressed to total loss in the last recurrence. The last recurrence showed homozygous deletions in CDKN2A and CDKN2B. The RASSF1 gene was hypermethylated during tumour evolution. In this report, we show the genetic alterations of a primary ccm and its recurrences to elucidate their relationships with the changes involved in the progression of this rare neoplasm.

[Prognostic variability in atypical meningioma with complete resection. Proposed treatment algorithm]

OBJECTIVE

The authors attempt to show how the current prognostic factors that try to assess the risk of recurrence of atypical meningiomas are insufficient to predict the future of this disease.

MATERIALS AND METHOD

Using data obtained from hospital databases, a sample of 27 patients was obtained with pathological diagnosis of atypical meningioma, and who had a minimum follow-up time of 6months after diagnosis. Later prognostic factors (age <50years, male gender, bone involvement, peri-lesional swelling, tumour volume, location, Ki67/MIB-1) were evaluated after the stratification of patients undergoing complete resection in recurrencies and non-recurrencies. Univariate analysis was performed using Mann-Whitney test, χ(2) homogeneity test/Fisher exact test. Finally, multivariate analysis was performed using binary logistic regression to obtain the values for R(2) Nagelkerke and the Hosmer-Lemeshow to evaluate the goodness of fit.

RESULTS

The uni- and multivariate analysis showed no statistically significant differences between recurrent and non-recurrent subgroups of patients undergoing complete resection. It is noted in the results that for each year of age above 50 years, the risk of recurrence is decreased by 5.8%.

CONCLUSIONS

Although current prognostic factors may show an increased risk of recurrence once patients are stratified by the two most important factors (pathology and extent of resection), those factors are insufficient to predict the ultimate outcome of patients affected by this pathology.

Molecular genetics of meningiomas: Building the roadmap towards personalized therapy

New advances have recently been made in the field of molecular genetics and mouse modeling of meningiomas, opening new perspectives for future treatments. Recent genome-wide genotyping and exome sequencing studies have confirmed the pivotal role of NF2 in meningioma tumorigenesis, concerning roughly half of the tumors, and unraveled new mutations in non-NF2 meningiomas concerning AKT1, SMO, KLF4 and TRAF7. The molecular mechanisms underlying tumorigenesis of high histological grades have been progressively deciphered with the recent discovery of TERT promoter mutations in progressing tumors. A better understanding of the genetics and clinical behavior of high-grade meningiomas is mandatory in order to better design future clinical trials. New genetically engineered mouse models of benign and histologically aggressive meningioma represent a substantial resource for the establishment of relevant pre-clinical trials. By studying the mechanisms underlying these new tumorigenesis pathways and the corresponding mouse models, we should be able to offer personalized chemotherapy to patients with surgery- and radiation-refractory meningiomas in the near future.

Gene expression profiles of metabolic aggressiveness and tumor recurrence in benign meningioma

Around 20% of meningiomas histologically benign may be clinically aggressive and recur. This strongly affects management of meningioma patients. There is a need to evaluate the potential aggressiveness of an individual meningioma. Additional criteria for better classification of meningiomas will improve clinical decisions as well as patient follow up strategy after surgery. The aim of this study was to determine the relationship between gene expression profiles and new metabolic subgroups of benign meningioma with potential clinical relevance. Forty benign and fourteen atypical meningioma tissue samples were included in the study. We obtained metabolic profiles by NMR and recurrence after surgery information for all of them. We measured gene expression by oligonucleotide microarray measurements on 19 of them. To our knowledge, this is the first time that distinct gene expression profiles are reported for benign meningioma molecular subgroups with clinical correlation. Our results show that metabolic aggressiveness in otherwise histological benign meningioma proceeds mostly through alterations in the expression of genes involved in the regulation of transcription, mainly the LMO3 gene. Genes involved in tumor metabolism, like IGF1R, are also differentially expressed in those meningioma subgroups with higher rates of membrane turnover, higher energy demand and increased resistance to apoptosis. These new subgroups of benign meningiomas exhibit different rates of recurrence. This work shows that benign meningioma with metabolic aggressiveness constitute a subgroup of potentially recurrent tumors in which alterations in genes regulating critical features of aggressiveness, like increased angiogenesis or cell invasion, are still no predominant. The determination of these gene expression biosignatures may allow the early detection of clinically aggressive tumors.

Iodothyronine deiodinases and cancer

Thyroid hormones (TH) regulate key cellular processes, including proliferation, differentiation, and apoptosis in virtually all human cells. Disturbances in TH pathway and the resulting deregulation of these processes have been linked with neoplasia. The concentrations of TH in peripheral tissues are regulated via the activity of iodothyronine deiodinases. There are 3 types of these enzymes: type 1 and type 2 deiodinases are involved in TH activation while type 3 deiodinase inactivates TH. Expression and activity of iodothyronine deiodinases are disturbed in different types of neoplasia. According to the limited number of studies in cancer cell lines and mouse models changes in intratumoral and extratumoral T3 concentrations may influence proliferation rate and metastatic progression. Recent findings showing that increased expression of type 3 deiodinases may lead to enhanced tumoral proliferation support the idea that deiodinating enzymes have the potential to influence cancer progression. This review summarizes the observations of impaired expression and activity in different cancer types, published to date, and the mechanisms behind these alterations, including impaired regulation via TH receptors, transforming growth factor-β, and Sonic-hedgehog pathway. Possible roles of deiodinases as cancer markers and potential modulators of tumor progression are also discussed.

DNA microarray analysis identifies CKS2 and LEPR as potential markers of meningioma recurrence

Meningiomas are the most frequent intracranial tumors. Surgery can be curative, but recurrences are possible. We performed gene expression analyses and loss of heterozygosity (LOH) studies looking for new markers predicting the recurrence risk. We analyzed expression profiles of 23 meningiomas (10 grade I, 10 grade II, and 3 grade III) and validated the data using quantitative polymerase chain reaction (qPCR). We performed LOH analysis on 40 meningiomas, investigating chromosomal regions on 1p, 9p, 10q, 14q, and 22q. We found 233 and 268 probe sets to be significantly down- and upregulated, respectively, in grade II or III meningiomas. Genes downregulated in high-grade meningiomas were overrepresented on chromosomes 1, 6, 9, 10, and 14. Based on functional enrichment analysis, we selected LIM domain and actin binding 1 (LIMA1), tissue inhibitor of metalloproteinases 3 (TIMP3), cyclin-dependent kinases regulatory subunit 2 (CKS2), leptin receptor (LEPR), and baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) for validation using qPCR and confirmed their differential expression in the two groups of tumors. We calculated ΔCt values of CKS2 and LEPR and found that their differential expression (C-L index) was significantly higher in grade I than in grade II or III meningiomas (p < .0001). Interestingly, the C-L index of nine grade I meningiomas from patients who relapsed in <5 years was significantly lower than in grade I meningiomas from patients who did not relapse. These findings indicate that the C-L index may be relevant to define the progression risk in meningioma patients, helping guide their clinical management. A prospective analysis on a larger number of cases is warranted.

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.

Metabolic aggressiveness in benign meningiomas with chromosomal instabilities

Meningiomas are often considered benign tumors curable by surgery, but most recurrent meningiomas correspond to histologic benign tumors. Because alterations in chromosome 14 among others have suggested clinical aggressiveness and recurrence, determining both the molecular phenotype and the genetic profile may help distinguish tumors with aggressive metabolism. The aim of this study was to achieve higher specificity in the detection of meningioma subgroups by measuring chromosomal instabilities by fluorescence in situ hybridization and cytogenetics and metabolic phenotypes by high-resolution magic angle spinning spectroscopy. We studied 46 meningioma biopsies with these methodologies. Of these, 34 were of WHO grade 1 and 12 were of WHO grade 2. Genetic analysis showed a subgroup of histologic benign meningioma with chromosomal instabilities. The metabolic phenotype of this subgroup indicated an aggressive metabolism resembling that observed for atypical meningioma. According to the metabolic profiles, these tumors had increased energy demand, higher hypoxic conditions, increased membrane turnover and cell proliferation, and possibly increased resistance to apoptosis. Taken together, our results identify distinct metabolic phenotypes for otherwise benign meningiomas based on cytogenetic studies and global metabolic profiles of intact tumors. Measuring the metabolic phenotype of meningioma intact biopsies at the same time as histopathologic analysis may allow the early detection of clinically aggressive tumors.

Genomic deletions at 1p and 14q are associated with an abnormal cDNA microarray gene expression pattern in meningiomas but not in schwannomas

The molecular pathology of meningiomas and shwannomas involve the inactivation of the NF2 gene to generate grade I tumors. Genomic losses at 1p and 14q are observed in both neoplasms, although more frequently in meningiomas. The inactivation of unidentified genes located in these regions appears associated with tumor progression in meningiomas, but no clues to its molecular/clinical meaning are available in schwannomas. Recent microarray gene expression studies have demonstrated the existence of molecular subgroups in both entities. In the present study, we correlated the presence of genomic deletions at 1p, 14q, and 22q with the expression patterns of 96 tumor-related genes obtained by cDNA low-density microarrays in a series of 65 tumors including 42 meningiomas and 23 schwannomas. Two expression pattern groups were identified by cDNA mycroarray analysis when compared to the expression pattern in normal control RNA in both meningiomas and schwannomas, each one with patterns similar and different from the normal control. Meningioma and schwannoma subgroups differed in the expression of 38 and 16 genes, respectively. Using MLPA and microsatellites, we identified genomic losses at 1p, 14q, and 22q at nonrandom frequencies (12.5-69%) in meningiomas and schwannomas. Losses at 22q were almost equally frequent in both molecular expression subgroups in both neoplasms. However, deletions at 1p and 14q accumulated in meningiomas with a gene expression pattern different from the normal pattern, whereas the inverse situation occurred in schwannomas. Those anomalies characterized the schwannomas with expression pattern similar to the normal control. These findings suggest that deletions at 1p and 14q enhance the development of an abnormal tumor-related gene expression pattern in meningiomas, but this fact is not corroborated in schwannomas.

Identification of the deleted in liver cancer 1 gene, DLC1, as a candidate meningioma tumor suppressor

OBJECTIVE

Meningiomas are the second most common primary tumors of the central nervous system. Meningiomas at the cranial base pose technical challenges and result in increased morbidity. To investigate the molecular mechanisms of meningioma formation, the expression profiles of 12 000 genes from meningiomas and dural specimens were compared.

METHODS

Ribonucleic acid from 6 meningiomas (World Health Organization Grade I) and 4 dural specimens was profiled using U95A GeneChips (Affymetrix, Inc., Santa Clara, CA). Expression profiles of the 2 groups were compared using dChip and Data Mining Tool software packages (Affymetrix, Inc.) to identify differentially expressed genes. Down-regulation of a differentially expressed tumor suppressor gene, deleted in liver cancer 1 (DLC1), was verified by quantitative real-time reverse transcription-polymerase chain reaction and immunohistochemical staining. Function and methylation of DLC1 were assessed by ectopic expression in 5 primary cultures, demethylation assay using 5-aza-2'-deoxycytidine, and methylation-specific polymerase chain reaction in 4 meningioma samples.

RESULTS

Gene expression profiling revealed up-regulation of 5 genes (fibroblast growth factor 9, gibbon leukemia virus receptor 2, cyclin D1, eukaryotic translation initiation factor 5A, and 28S ribosomal ribonucleic acid) and down-regulation of 35 genes, including DLC1, in meningiomas. The down-regulation of DLC1 in meningiomas was confirmed by quantitative real-time reverse transcription-polymerase chain reaction and immunohistochemical staining. Transfection of DLC1 complementary deoxyribonucleic acid into primary cultures of 5 meningiomas resulted in decreased replication. Although demethylation decreased meningioma cell growth rates in vitro, methylation-specific polymerase chain reaction did not detect DLC1 promoter methylation.

CONCLUSION

The results suggest that DLC1 may function as a tumor suppressor gene in meningiomas. Furthermore, DLC1 promoter methylation does not appear to be responsible for the decreased DLC1 expression in these tumors.

Array-based comparative genomic hybridization of mapped BAC DNA clones to screen for chromosome 14 copy number abnormalities in meningiomas

Chromosome 14 loss in meningiomas are associated with more aggressive tumour behaviour. To date, no studies have been reported in which the entire chromosome 14q of meningioma tumour cells has been studied by high-resolution array comparative genomic hybridization (a-CGH). Here, we used a high-resolution a-CGH to define the exact localization and extent of numerical changes of chromosome 14 in meningioma patients. An array containing 807 bacterial artificial chromosome clones specific for chromosome 14q (average resolution of approximately 130 Kb) was constructed and applied to the study of 25 meningiomas in parallel to the confirmatory interphase fluorescence in situ hybridization (iFISH) analyses. Overall, abnormalities of chromosome 14q were detected in 10/25 cases (40%). Interestingly, in seven of these cases, loss of chromosome 14q32.3 was detected by iFISH and confirmed to correspond to monosomy 14 by a-CGH. In contrast, discrepant results were found between iFISH and a-CGH in the other three altered cases. In one patient, a diploid background was observed by iFISH, while monosomy 14 was identified by a-CGH. In the remaining two cases, which showed gains of the IGH gene by iFISH, a-CGH did not detected copy number changes in one case showing a tetraploid karyotype, while in the other tumour, varying genetic imbalances along the long arm of chromosome 14 were detected. In summary, here, we report for the first time, the high-resolution a-CGH profiles of chromosome 14q in meningiomas, confirming that monosomy 14 is the most frequent alteration associated with this chromosome; other numerical abnormalities being only sporadically detected.

De novo versus transformed atypical and anaplastic meningiomas: comparisons of clinical course, cytogenetics, cytokinetics, and outcome

OBJECTIVE

The clinical course of atypical and anaplastic meningiomas is heterogeneous. As malignant gliomas, aggressive meningiomas may arise de novo or transform from a benign tumor. This study aims to compare differences in clinical behavior, cytogenetics, cytokinetics, receptor status, and outcome between de novo malignant meningiomas and meningiomas that progressed to malignancy.

METHODS

Data from 36 patients with atypical or anaplastic meningiomas were selected for retrospective analysis and divided into two subgroups: 1) de novo atypical or anaplastic tumors and 2) tumors that progressed from a lower grade. We analyzed data concerning patients' sex, age, tumor location, number of operations, status of hormone receptors, proliferative indices, cytogenetic findings, additional therapy, and survival. For meningiomas with progression, we calculated the interval between initial diagnosis and tumor progression.

RESULTS

For atypical meningiomas, the subgroups had significant differences in status of progesterone receptors, proliferative indices, cytogenetics, and patients' outcome. The anaplastic group had similar differences, but they did not reach statistical significance because of the small numbers. There was a loss of part or monosomy of chromosome 10 and an increased monosomy or derivative chromosome 1 combined with monosomy of chromosome 14. These phenomena occurred mainly in patients with malignant transformation who had a worse outcome.

CONCLUSION

De novo malignant meningiomas and meningiomas with malignant transformation may represent distinct subgroups of atypical and anaplastic meningiomas.

Early recurrences in histologically benign/grade I meningiomas are associated with large tumors and coexistence of monosomy 14 and del(1p36) in the ancestral tumor cell clone

Tumor recurrence is the major clinical complication in meningiomas, and its prediction in histologically benign/grade I tumors remains a challenge. In this study, we analyzed the prognostic value of specific chromosomal abnormalities and the genetic heterogeneity of the tumor, together with other clinicobiological disease features, for predicting early relapses in histologically benign/grade I meningiomas. A total of 149 consecutive histologically benign/grade I meningiomas in patients who underwent complete tumor resection were prospectively analyzed. Using interphase fluorescence in situ hybridization, we studied the prognostic impact of the abnormalities detected for 11 different chromosomes, together with other relevant clinicobiological and histopathological characteristics of the disease, on recurrence-free survival (RFS) at 2.5, 5, and 10 years. From the prognostic point of view, losses of chromosomes 9, 10, 14, and 18 and del(1p36) were associated with a shorter RFS at 2.5, 5, and 10 years. Similarly, histologically benign/grade I meningiomas showing coexistence of monosomy 14 and del(1p36) in the ancestral tumor cell clone displayed a higher frequency of early relapses. In fact, coexistence of -14 and del(1p36) in the ancestral tumor cell clone, together with tumor size, represented the best combination of independent prognostic factors for the identification of those patients with a high risk of an early relapse. Our results indicate that patients with large histologically benign/grade I meningiomas carrying monosomy 14 and del(1p36) in their ancestral tumor cell clone have a high probability of relapsing early after diagnostic surgery. These findings suggest the need for closer follow-up in this small group of patients.

Establishment of an in vivo meningioma model with human telomerase reverse transcriptase

OBJECTIVE

The lack of meningioma models has hindered research on the pathogenesis and treatment of this commonly diagnosed primary brain tumor. Animal models of meningioma have been difficult to develop, especially those derived from Grade I tumors, which display very slow growth rates, senesce at early passages, and infrequently survive as explants in vivo. In this study, the authors report the establishment of two benign immortalized meningioma cell lines, Me10T and Me3TSC, that can serve as useful models of human meningioma.

METHODS

Tissue specimens obtained at the time of surgery were cultured in vitro and transduced with human telomerase reverse transcriptase/SV40 large T antigen to establish long-term cell lines. The telomeric activity, growth kinetics, immunophenotype, and karyotyping of the cell lines were investigated. The growth inhibitory effects of the antitumor therapies, hydroxyurea and sodium butyrate, on these cell lines were determined. In addition, immortalized cell lines were implanted subdurally into mice to confirm their ability to form tumors.

RESULTS

Two immortalized benign meningioma cell lines, Me10T and Me3TSC, transduced with catalytic subunit human telomerase reverse transcriptase alone or human telomerase reverse transcriptase and SV40 large T antigen, were established. The meningeal phenotype of the established cell cultures and orthotopic xenografts was confirmed by immunostaining. After subdural injection into athymic nude mice, both cell lines formed identifiable tumors with histological features and immunostaining patterns of human meningioma.

CONCLUSION

The Me3TSC and Me10T cell lines can serve as useful model systems for biological studies and the evaluation of novel therapies on meningioma.

Chromosome 1p36 and 22qter deletions in paraffin block sections of intracranial meningiomas

Meningiomas are the most frequent benign tumors of the intracranial cavity. The classification and underlying pathogenetic mechanisms have been reported to be investigated by both pathological and genetic methods. In this study, we aimed to detect 1p36 and 22qter deletions by fluorescence in situ hybridization (FISH) in archival materials of 50 intracranial meningioma patients. The clinical material consisted of paraffin-embedded tissue sections from 50 patients who were surgically treated and had histopathologic diagnosis of an intracranial meningioma. We observed 1p36 deletion in 23/50 (46%) and 22qter deletion in 33/50 (66%) patients. In addition, we observed 22qter deletion in 26/36 (72.2%) patients with meningothelial meningioma. This finding implies that 22qter deletion might play an important role in the pathogenesis of meningothelial meningioma. On the other hand, no alterations were documented in the frequency of these chromosomal alterations according to the grade of meningiomas, suggesting that malignant progression of these tumors depends on other, more relevant, genetic changes.

Molecular cytogenetic analysis in the study of brain tumors: findings and applications

Classic cytogenetics has evolved from black and white to technicolor images of chromosomes as a result of advances in fluorescence in situ hybridization (FISH) techniques, and is now called molecular cytogenetics. Improvements in the quality and diversity of probes suitable for FISH, coupled with advances in computerized image analysis, now permit the genome or tissue of interest to be analyzed in detail on a glass slide. It is evident that the growing list of options for cytogenetic analysis has improved the understanding of chromosomal changes in disease initiation, progression, and response to treatment. The contributions of classic and molecular cytogenetics to the study of brain tumors have provided scientists and clinicians alike with new avenues for investigation. In this review the authors summarize the contributions of molecular cytogenetics to the study of brain tumors, encompassing the findings of classic cytogenetics, interphase- and metaphase-based FISH studies, spectral karyotyping, and metaphase- and array-based comparative genomic hybridization. In addition, this review also details the role of molecular cytogenetic techniques in other aspects of understanding the pathogenesis of brain tumors, including xenograft, cancer stem cell, and telomere length studies.

Molecular diagnostics in central nervous system tumors

Central nervous system (CNS) neoplasms can be diagnostically challenging, due to remarkably wide ranges in histologic appearance, biologic behavior, and therapeutic approach. Nevertheless, accurate diagnosis is the critical first step in providing optimal patient care. As with other oncology-based specialties, there is a rapidly expanding interest and enthusiasm for identifying and utilizing new biomarkers to enhance the day-to-day practice of surgical neuropathology. In this regard, the field is primed by recent advances in basic research, elucidating the molecular mechanisms of tumorigenesis and progression in the most common adult and pediatric brain tumors. Thus far, few have made the transition into routine clinical practice, the most notable example being 1p and 19q testing in oligodendroglial tumors. However, the field is rapidly evolving and many other biomarkers are likely to emerge as useful ancillary diagnostic, prognostic, or therapeutic aids. The goal of this article is to highlight the most common genetic alterations currently implicated in CNS tumors, focusing most on those that are either already in common use in ancillary molecular diagnostics testing or are likely to become so in the near future.

Meningioma: an update

PURPOSE OF REVIEW

Recent clinical and molecular research has shed new light on the biology of meningiomas--a common but understudied CNS neoplasm. This review will focus on recent advances and their significance for future research and treatment.

RECENT FINDINGS

Meningiomas represent the second most common brain tumor in adults, and while improved diagnostic modalities are available, these tumors remain underreported. Radiosurgery is an effective adjuvant therapy against meningioma; however, no effective chemotherapy exists. In addition to histologic grading and estimates of the extent of resection, biomarkers, such as progesterone receptor, cyclooxygenase 2, S100A5 and ornithine decarboxylase may be useful in predicting tumor recurrence and/or progression potential in patients with meningioma. On the genetic level, cytogenetic losses on chromosomes 1, 7, 10 and 14 and telomerase activation are observed in clinically aggressive meningioma, whereas monosomy 22 is a common early molecular event in tumor formation. Several candidate growth regulatory genes have been identified, including the Neurofibromatosis 2 (NF2), Tumor Suppressor in Lung Cancer-1 (TSLC1), Protein 4.1B, p53/MDM2 and S6-Kinase genes. The roles of these genes in meningioma formation and progression, as well as the clinical implications of these genetic changes, are discussed.

SUMMARY

The recent insights into the molecular biology and genetics of meningioma provide new avenues for basic science research aimed at understanding the mechanisms underlying meningioma formation and malignant progression. These advances may be useful in improving our ability to predict clinical outcome and developing targeted therapies to improve outcomes in patients with clinically aggressive meningiomas.

Genetic and epigenetic alteration of theNF2gene in sporadic meningiomas

The role of the NF2 gene in the development of meningiomas has recently been documented; inactivating mutations plus allelic loss at 22q, the site of this gene (at 22q12), have been identified in both sporadic and neurofibromatosis type 2-associated tumors. Although epigenetic inactivation through aberrant CpG island methylation of the NF2 5' flanking region has been documented in schwannoma (another NF2-associated neoplasm), data on participation of this epigenetic modification in meningiomas are not yet widely available. Using methylation-specific PCR (MSP) plus sequencing, we assessed the presence of aberrant promoter NF2 methylation in a series of 88 meningiomas (61 grade I, 24 grade II, and 3 grade III), in which the allelic constitution at 22q and the NF2 mutational status also were determined by RFLP/microsatellite and PCR-SSCP analyses. Chromosome 22 allelic loss, NF2 gene mutation, and aberrant NF2 promoter methylation were detected in 49%, 24%, and 26% of cases, respectively. Aberrant NF2 methylation with loss of heterozygosity (LOH) at 22q was found in five cases, and aberrant methylation with NF2 mutation in another; LOH 22q and the mutation were found in 16 samples. The aberrant methylation of the NF2 gene also was the sole alteration in 15 samples, most of which were from grade I tumors. These results indicate that aberrant NF2 hypermethylation may participate in the development of a significant proportion of sporadic meningiomas, primarily those of grade I.

DNA methylation of multiple promoter-associated CpG islands in meningiomas: relationship with the allelic status at 1p and 22q

The purpose of this research was to examine the DNA methylation profile of meningiomas. Accordingly, we examined the DNA methylation status of ten tumor-related genes (RB1, p16(INK4a), p73, MGMT, ER, DAPK, TIMP-3, p14(ARF), THBS1, and Caspase-8) in 98 meningiomas (68 grade I; 27 grade II; and 3 grade III samples) using methylation-specific PCR and sequencing. The most frequently methylated genes were THBS1 (30%), TIMP-3 (24%), p16(INK4a) (17%), MGMT (16%), p73 (15%), ER (15%), and p14(ARF) (13%), whereas methylation was relatively rare in the other genes (<10%). Methylation occurred in at least one gene in 77.5% of the cases and in three or more genes in 25.5%. Methylation was tumor specific since it was absent in the controls: two non-neoplastic meningeal samples and two non-neoplastic brain samples. The frequency of aberrant gene methylation in grade I versus grade II-III tumors showed some differences for TIMP-3, THBS1, MGMT, p16(INK4a) and p73; these differences reached statistical significance for TIMP-3: 18% in grade I versus 40% in grade II-III (P < 0.02). Our previous loss of heterozygosity studies provided the allelic constitution at 1p and 22q for 60 of the 98 meningiomas included in this report. The level of aberrant promoter methylation increased in tumors (30 samples) displaying 1p loss (either isolated or as concurrent deletion at 1p/22q; P = 0.014). These meningiomas primarily accumulated the epigenetic changes of THBS1 (14/30; 47%; P < 0.005), TIMP-3 (12/30; 40%; P < 0.05), p73 (10/30; 26%; P < 0.02) and p14(ARF) /p16(INK4a)(7/30 each one; 23%; not significant). Our findings indicate that aberrant DNA methylation of promoter-associated CpG islands in meningiomas contributes to the development of these tumors.