Cytogenetic, molecular genetic and pathological analyses in 126 meningiomas

Multiple ossified intracranial and spinal meningiomas: a rare case report and literature review

Ossified intracranial meningiomas (OIM) and ossified spinal meningiomas (OSM) are rare neoplasms of mesenchymal origin that predominantly manifest in the spinal cord and infrequently in the cranial region, accounting for ~0. 7-5.5% of all meningiomas. It is extremely rare to have multiple intracranial and spinal lesions accompanied by ossification. Herein, we report this rare case for the first time. A 34-year-old woman presented with paresthesia and limb weakness in the right lower limb and gradually worsened. Approximately half a year later, she could only walk with crutches. Magnetic resonance imaging of the brain and spinal cord showed multiple meningiomas, and histopathological examination confirmed multiple OIM and OSM (WHO grade 1). Multiple OIM and OSM are extremely rare with diverse imaging features, and it is easily confused with other tumors. Histopathological examination is the final diagnostic method.

Signaling pathways in brain tumors and therapeutic interventions

Brain tumors, although rare, contribute to distinct mortality and morbidity at all ages. Although there are few therapeutic options for brain tumors, enhanced biological understanding and unexampled innovations in targeted therapies and immunotherapies have considerably improved patients' prognoses. Nonetheless, the reduced response rates and unavoidable drug resistance of currently available treatment approaches have become a barrier to further improvement in brain tumor (glioma, meningioma, CNS germ cell tumors, and CNS lymphoma) treatment. Previous literature data revealed that several different signaling pathways are dysregulated in brain tumor. Importantly, a better understanding of targeting signaling pathways that influences malignant behavior of brain tumor cells might open the way for the development of novel targeted therapies. Thus, there is an urgent need for a more comprehensive understanding of the pathogenesis of these brain tumors, which might result in greater progress in therapeutic approaches. This paper began with a brief description of the epidemiology, incidence, risk factors, as well as survival of brain tumors. Next, the major signaling pathways underlying these brain tumors' pathogenesis and current progress in therapies, including clinical trials, targeted therapies, immunotherapies, and system therapies, have been systemically reviewed and discussed. Finally, future perspective and challenges of development of novel therapeutic strategies in brain tumor were emphasized.

Radiation-Induced Meningiomas

While the majority of meningiomas encountered clinically are sporadic, there is a rare subset that arises due to early life or childhood irradiation. Sources of this radiation exposure may be due to treatment of other cancers such as acute childhood leukemia, other central nervous system tumors such as medulloblastoma, the treatment of tinea capitis (rarely and historically), or environmental exposures, as seen in some of the Hiroshima and Nagasaki atomic bomb survivors. Regardless of their etiology, however, radiation-induced meningiomas (RIMs) tend to be highly biologically aggressive irrespective of WHO grade and are usually refractory to the conventional treatment modalities of surgery and/or radiotherapy. In this chapter, we will discuss these RIMs in their historical context, their clinical presentation, their genomic features and ongoing efforts to better understand these tumors from a biological standpoint in order to develop better, more efficacious therapies for these patients.

Correlation between DNA Methylation and Cell Proliferation Identifies New Candidate Predictive Markers in Meningioma

Meningiomas are the most common primary tumors of the central nervous system. Based on the 2021 WHO classification, they are classified into three grades reflecting recurrence risk and aggressiveness. However, the WHO's histopathological criteria defining these grades are somewhat subjective. Together with reliable immunohistochemical proliferation indices, other molecular markers such as those studied with genome-wide epigenetics promise to revamp the current prognostic classification. In this study, 48 meningiomas of various grades were randomly included and explored for DNA methylation with the Infinium MethylationEPIC microarray over 850k CpG sites. We conducted differential and correlative analyses on grade and several proliferation indices and markers, such as mitotic index and Ki-67 or MCM6 immunohistochemistry. We also set up Cox proportional hazard models for extensive associations between CpG methylation and survival. We identified loci highly correlated with cell growth and a targeted methylation signature of regulatory regions persistently associated with proliferation, grade, and survival. Candidate genes under the control of these regions include SMC4, ESRRG, PAX6, DOK7, VAV2, OTX1, and PCDHA-PCDHB-PCDHG, i.e., the protocadherin gene clusters. This study highlights the crucial role played by epigenetic mechanisms in shaping dysregulated cellular proliferation and provides potential biomarkers bearing prognostic and therapeutic value for the clinical management of meningioma.

Clinical Management of Supratentorial Non-Skull Base Meningiomas

Supratentorial non-skull base meningiomas are the most common primary central nervous system tumor subtype. An understanding of their pathophysiology, imaging characteristics, and clinical management options will prove of substantial value to the multi-disciplinary team which may be involved in their care. Extensive review of the broad literature on the topic is conducted. Narrowing the scope to meningiomas located in the supratentorial non-skull base anatomic location highlights nuances specific to this tumor subtype. Advances in our understanding of the natural history of the disease and how findings from both molecular pathology and neuroimaging have impacted our understanding are discussed. Clinical management and the rationale underlying specific approaches including observation, surgery, radiation, and investigational systemic therapies is covered in detail. Future directions for probable advances in the near and intermediate term are reviewed.

The Hypothesis of the Prolonged Cell Cycle in Turner Syndrome

Turner syndrome (TS) is a chromosomal disorder that is caused by a missing or structurally abnormal second sex chromosome. Subjects with TS are at an increased risk of developing intrauterine growth retardation, low birth weight, short stature, congenital heart diseases, infertility, obesity, dyslipidemia, hypertension, insulin resistance, type 2 diabetes mellitus, metabolic syndrome, and cardiovascular diseases (stroke and myocardial infarction). The underlying pathogenetic mechanism of TS is unknown. The assumption that X chromosome-linked gene haploinsufficiency is associated with the TS phenotype is questioned since such genes have not been identified. Thus, other pathogenic mechanisms have been suggested to explain this phenotype. Morphogenesis encompasses a series of events that includes cell division, the production of migratory precursors and their progeny, differentiation, programmed cell death, and integration into organs and systems. The precise control of the growth and differentiation of cells is essential for normal development. The cell cycle frequency and the number of proliferating cells are essential in cell growth. 45,X cells have a failure to proliferate at a normal rate, leading to a decreased cell number in a given tissue during organogenesis. A convergence of data indicates an association between a prolonged cell cycle and the phenotypical features in Turner syndrome. This review aims to examine old and new findings concerning the relationship between a prolonged cell cycle and TS phenotype. These studies reveal a diversity of phenotypic features in TS that could be explained by reduced cell proliferation. The implications of this hypothesis for our understanding of the TS phenotype and its pathogenesis are discussed. It is not surprising that 45,X monosomy leads to cellular growth pathway dysregulation with profound deleterious effects on both embryonic and later stages of development. The prolonged cell cycle could represent the beginning of the pathogenesis of TS, leading to a series of phenotypic consequences in embryonic/fetal, neonatal, pediatric, adolescence, and adulthood life.

Intraventricular meningiomas frequently harbor NF2 mutations but lack common genetic alterations in TRAF7, AKT1, SMO, KLF4, PIK3CA, and TERT

Intraventricular meningiomas (IVMs) account for less than 5% of all intracranial meningiomas; hence their molecular phenotype remains unknown. In this study, we were interested whether genetic alterations in IVMs differ from meningiomas in other locations and analyzed our institutional series with respect to clinical and molecular characteristics. A total of 25 patients with surgical removal of an IVM at our department between 1986 and 2018 were identified from our institutional database. Median progression-free survival (PFS) was 79 months (range of 2–319 months) and PFS at 5 years was 86%. Corresponding tumor tissue was available for 18 patients including one matching recurrence and was subjected to targeted panel sequencing of 130 selected genes frequently mutated in brain cancers by applying a custom hybrid capture approach on a NextSeq500 instrument. Loss of chromosome 22q and 1p occurred frequently in 89 and 44% of cases. Deleterious NF2 mutations were found in 44% of IVMs (n = 8/18). In non-NF2-mutated IVMs, previously reported genetic alterations including TRAF7, AKT1, SMO, KLF4, PIK3CA, and TERT were lacking, suggesting alternative genes in the pathogenesis of non-NF2 IVMs. In silico analysis revealed possible damaging mutations of APC, GABRA6, GSE1, KDR, and two SMO missense mutations differing from previously reported ones. Interestingly, all WHO°II IVMs (n = 3) harbored SMARCB1 and SMARCA4 mutations, indicating a role of the SWI/SNF chromatin remodeling complex in aggressive IVMs.

Masked hypodiploidy in anaplastic meningiomas by duplication of the original clone found in atypical meningiomas: illustration of the evolution of genetic alterations

Meningiomas are common, usually benign neoplasms of the central nervous system. Atypical and anaplastic meningiomas can be aggressive, show more rapid growth, and a greater propensity to recur following resection. General consensus believes that genetic abnormalities leading to anaplastic transformation are present at initial tumor presentation; however, this has not been demonstrated by array-comparative genome hybridization. We confirm the hypothesis by showing the evolution of genetic alterations in the transformation of an atypical meningioma to an anaplastic meningioma. Additionally, we provide potential genes responsible for malignant transformation of meningiomas, which, with further research, may provide diagnostic and therapeutic implications.

Merlin: a tumour suppressor with functions at the cell cortex and in the nucleus

Inhibition of proliferation by cell-to-cell contact is essential for tissue organization, and its disruption contributes to tumorigenesis. The FERM domain protein Merlin, encoded by the NF2 tumour suppressor gene, is an important mediator of contact inhibition. Merlin was thought to inhibit mitogenic signalling and activate the Hippo pathway by interacting with diverse target-effectors at or near the plasma membrane. However, recent studies highlight that Merlin pleiotropically affects signalling by migrating into the nucleus and inducing a growth-suppressive programme of gene expression through its direct inhibition of the CRL4DCAF1 E3 ubiquitin ligase. In addition, Merlin promotes the establishment of epithelial adhesion and polarity by recruiting Par3 and aPKC to E-cadherin-dependent junctions, and by ensuring the assembly of tight junctions. These recent advances suggest that Merlin acts at the cell cortex and in the nucleus in a similar, albeit antithetic, manner to the oncogene β-catenin.

Constitutional aneuploidy and cancer predisposition

Constitutional aneuploidies are rare syndromes associated with multiple developmental abnormalities and the alterations in the risk for specific cancers. Acquired somatic chromosomal aneuploidies are the most common genetic aberrations in sporadic cancers. Thus studies of these rare constitutional aneuploidy syndromes are important not only for patient counseling and clinical management, but also for deciphering the mechanisms by which chromosomal aneuploidy affect cancer initiation and progression. Here we review the major constitutional aneuploidy syndromes and suggest some general mechanisms for the associated cancer predisposition.

A role for the p53 pathway in the pathology of meningiomas with NF2 loss

The neurofibromatosis 2 locus (NF2) is inactivated through mutation and loss of heterozygosity (LOH) in 40-65% of all sporadic meningiomas, while the role of the p53 tumor suppression pathway in meningioma initiation and progression is still unclear. This study aims to determine if a p53 codon 72 arginine-to-proline polymorphism, found to be correlated with cancer development and cancer patient survival in other tumors, is associated with sporadic meningioma initiation or progression. We investigated Pro72 incidence in a cohort of 92 sporadic meningiomas and analyzed its association with histological grade (WHO classification) and with NF2 LOH (determined using polymorphic microsatellite markers on 22q). The Pro72 allele was not found to be selected for in the cohort. However, in the subgroup of meningiomas with NF2 LOH and carrying Pro72, 50.0% had high grade tumors (WHO grades II and III) compared to only 14.3% of those without NF2 LOH (OR = 6.0, CI = 1.56-23.11, P = 0.012). The significant association occurred only when considering subgroups of meningiomas with or without NF2 LOH, suggesting that not including NF2 status when analyzing study cohorts may explain the variability seen in the literature where all meningiomas were grouped together. Our data suggests a role for the p53 pathway in the progression of meningiomas in which NF2 is inactivated, and highlights the importance of accounting for NF2 LOH in future studies of meningiomas and the p53 pathway.

Gene expression profiles of meningiomas are associated with tumor cytogenetics and patient outcome

Cytogenetic analysis is a powerful tool for predicting recurrence in meningiomas, even among histologically benign/grade I tumors. Despite this, no study has been reported in which the impact of tumor cytogenetics on the gene expression profiles (GEP) has been analyzed in meningiomas. Here, we analyzed the GEP of 47 tumors and correlated them with the most clinical relevant cytogenetic subgroups of meningiomas, as confirmed through the analysis of 172 patients. Additionally three normal meningeal samples were also studied. Overall, our results show a clear association between the clinically relevant cytogenetic subgroups of meningiomas including diploid tumors (n = 18), isolated -22/22q- (n = 12), del(1p36) alone (n = 4) and complex karyotypes associated with del(1p36) and/or -14q (n = 13) and their GEP. Accordingly, based on the expression of 85 genes (40 of which were coded in the altered chromosomes used for patient stratification) the cytogenetic class of the tumor could be predicted with an error of <1%, a clear association being found between the GEP and patient outcome (P = 0.03) but not tumor histopathology. In summary, we show a clear association between GEP of neoplastic cells and clinically relevant cytogenetic subgroups of meningiomas.

Cancer incidence in women with Turner syndrome in Great Britain: a national cohort study

BACKGROUND

Turner syndrome, one of the most common cytogenetic abnormalities, is characterised by complete or partial X-chromosome monosomy. Cancer risks in women with Turner syndrome have not been clearly established. We aimed to compare the risk of cancer in women with this syndrome with that of the general population.

METHODS

We formed a national cohort of 3425 women who were cytogenetically diagnosed with Turner syndrome in Great Britain between 1959 and 2002. Identifying information for these patients was sent to the National Health Service Central Register (NHSCR) for England and Wales and to the NHSCR for Scotland. Individuals who were identified on this register were followed-up for cancer incidence. Standardised incidence ratios (SIRs) and 95% CIs were calculated on the basis of the number of cancers observed compared with that expected based on national incidence rates. Cumulative risk estimates were obtained by use of the Kaplan-Meier method.

FINDINGS

A total of 58,299 person-years were accrued during the study, with a mean of 17.0 years (SD 8.6) follow-up per patient. 73 malignancies other than non-melanoma skin cancer occurred (SIR 0.9 [95% CI 0.7-1.2]). Risks were significantly increased for tumours of the CNS (n=13; 4.3 [2.3-7.4]), especially for meningioma (n=7; 12.0 [4.8-24.8]) and childhood brain tumours (n=3; 10.3 [2.1-30.1]), and for cancers of the bladder and urethra (n=5; 4.0 [1.3-9.2]) and eye (n=2; 10.5 [1.3-37.9]), compared with the general population. However, the risk of breast cancer was significantly decreased (n=10; 0.3 [0.2-0.6]). The SIR for cutaneous melanoma was 2.2 (95% CI 1.0-4.4; n=8), and one of the ocular cancers was a melanoma. The risk of corpus uteri cancer was significantly increased at ages 15-44 years (n=3; 8.0 [1.6-23.2]). During follow-up, five women, all with a Y-chromosome lineage, developed gonadoblastoma of the ovary, corresponding to a cumulative risk of 7.9% (95% CI 3.1-19.0) by age 25 years in this group.

INTERPRETATION

This study shows that, in addition to having an increased risk of gonadoblastoma, women with Turner syndrome seem to be at increased risk for meningioma and childhood brain tumours, and possibly bladder cancer, melanoma, and corpus uteri cancer, but are at a decreased risk for breast cancer. Reasons for these risks might relate to genetic and hormonal factors or to the effects of hormonal treatments given to women with Turner syndrome.

Patient gender is associated with distinct patterns of chromosomal abnormalities and sex chromosome linked gene-expression profiles in meningiomas

The female predominance of meningiomas has been established, but how this is affected by hormones is still under discussion. We analyzed the characteristics of meningiomas from male (n = 53) and female (n = 111) patients by interphase fluorescence in situ hybridization (iFISH). In addition, in a subgroup of 45 (12 male and 33 female) patients, tumors were hybridized with the Affymetrix U133A chip. We show a higher frequency of larger tumors (p = .01) and intracranial meningiomas (p = .04) together with a higher relapse rate (p = .03) in male than in female patients. Male patients had a higher percentage of del(1p36) (p < .001), while loss of an X chromosome was restricted to tumors from female patients (p = .008). In turn, iFISH studies showed a higher frequency of chromosome losses, other than monosomy 22 alone, in meningiomas from male patients (p = .002), while female patients displayed a higher frequency of chromosome gains (p = .04) or monosomy 22 alone (p = .03) in the ancestral tumor clone. Interestingly, individual chromosomal abnormalities had a distinct impact on the recurrence-free survival rate of male versus female patients. In turn, gene expression showed that eight genes (RPS4Y1, DDX3Y, JARID1D, DDX3X, EIF1AY, XIST, USP9Y, and CYorf15B) had significantly different expression patterns (R(2) > 0.80; p < .05) in tumors from male and female patients. In summary, we show the existence of different patterns of chromosome abnormalities and gene-expression profiles associated with patient gender, which could help to explain the slightly different clinical behavior of these two patient groups.

[Cytogenetic alterations in meningioma tumors and their impact on disease outcome]

In recent years important advances have been achieved in the understanding of the genetic abnormalities present in meningioma tumors and its association with the ontogeny and progression of these tumor. Accordingly, while the presence of monosomy 22/22q-, associated with mutation of the NF2, BAM22, RRP22, GAR22, MN1, SMARCB1, CLH22 and/or LARGE genes, is associated with neoplasic transformation, other alterations such us monosomy 14, del(1p), different chromosomal abnormalities localized at 9p, 10q and 17q and complex karyotypes are frequently related to tumor progression. From the clinical point of view, currently available information about the impact of the different cytogenetic abnormalities on disease behavior and patient outcome is still scanty; nevertheless, the presence of gains of chromosome 22 in the context of a hyperdiploid karyotype, as well as del(1p) and monosomy 14 have been associated with a statistically significantly shorter recurrence-free survival, this later abnormality showing an independent prognostic value.

Microarray-Based Analysis of Spinal versus Intracranial Meningiomas: Different Clinical, Biological, and Genetic Characteristics Associated with Distinct Patterns of Gene Expression

It has long been recognized that spinal meningiomas show particular clinical and histological features. Here, we compare the clinico-biological characteristics as well as the genetic abnormalities and patterns of gene expression of spinal and intracranial meningiomas. Fourteen spinal and 141 intracranial meningioma patients were analyzed at diagnosis. In all tumors, interphase fluorescence in situ hybridization (iFISH) studies were performed for the detection of quantitative abnormalities for 11 different chromosomes. Additionally, microarray analyses were performed on a subgroup of 18 histologically benign meningiomas (7 spinal and 11 intracranial). Upon comparison with intracranial tumors, spinal meningiomas showed a marked predominance of psammomatous and transitional tumors (p = 0.001), together with a higher proportion of cases displaying a single tumor cell clone by iFISH (p = 0.004). In 86% of the spinal versus 56% of the intracranial tumors (p = 0.01), the ancestral tumor cell clone detected showed either absence of any chromosomal abnormality or monosomy 22/22q- alone. Analysis of gene expression profiles showed differential expression between spinal and intracranial meningiomas for a total of 1555 genes, 35 of which allowed a clear distinction between both tumor types. Most of these 35 genes (n = 30) showed significantly higher expression among spinal tumors and corresponded to genes involved in signal transduction pathways, which did not show a significantly different expression according to tumor histopathology. In summary, we show the occurrence of unique patterns of genetic abnormalities and gene expression profiles in spinal as compared to intracranial meningiomas that provide new insights into the molecular pathways involved in the tumorigenesis and progression of spinal meningiomas, and could help explain their particular clinical and histological features.

Lack of genetic and epigenetic changes in meningiomas without NF2 loss

Approximately 60% of sporadic meningiomas are caused by inactivation of the NF2 tumour suppressor gene. The causative gene for the remaining meningiomas is unknown. Previous studies have shown that these tumours have no recurrent karyotypic abnormalities. They differ from their NF2-related counterparts in that they are more often of the meningothelial subtype and are located preferentially in the anterior skull base. To gain more insight into the aetiology of these tumours, we studied genetic and epigenetic alterations in 25 meningiomas without NF2 involvement. We first established a genome-wide allelotype using 3 microsatellite markers per chromosome arm. Loss of heterozygosity (LOH) was detected at a low frequency and no indication for the location of putative tumour suppressor genes could be established. We next screened the subtelomeric regions by using 2-3 polymorphic markers close to each telomere. Again no evidence for LOH of a particular chromosome arm was obtained, and no LOH was found in the genomic regions containing the NF2-related ERM family members ezrin and radixin, DAL-1, protein 4.1R, and TSLC1. Mutations in the X-chromosome based family member, moesin, were analysed by SSCP and were not detected. Microsatellite instability was studied using 6 commonly used markers but none of these was altered in any meningioma. Methylation was detected in 5 of 16 genes (NF2, p14(ARF), CDH1, BRCA1, RB1) previously shown to be silenced in a variety of tumour types. However, methylation percentages for these genes were generally higher in a group of NF2-related meningiomas, with the exception of the BRCA1 gene. The NF2 gene was methylated in only 1 of 21 tumours. In conclusion, meningiomas with an intact NF2 gene have a normal karyotype and no obvious genetic or epigenetic aberrations, suggesting that the gene(s) involved in the pathogenesis of these tumours are altered by smaller events than can be detected with the techniques used in our study.

Molecular genetics of meningiomas

In this article the authors provide a brief description of the current understanding of meningioma genetics. Chromosome 22 abnormalities, especially in the Neurofibromatosis Type 2 (NF2) gene, have been associated with meningioma development. Loss of heterozygosity of chromosome 22 occurs in approximately 60% of meningiomas; however, loss of NF2 gene function occurs in only one third of these lesions. This discrepancy supports the theory that a second tumor suppressor gene exists on chromosome 22, and the authors introduce several possible gene candidates, including BAM22, LARGE, INI1, and MN1 genes. Deletions of 1p have also been shown to correlate with meningioma progression. The genetic similarities and differences among sporadic, NF2-associated, pediatric, and radiation-induced meningiomas are discussed, with the observation that the nonsporadic meningiomas have a higher incidence of multiple chromosomal abnormalities at presentation. Ultimately, a better understanding of the molecular pathways of meningioma tumorigenesis will lead to new, successful treatments.

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.

Loss of heterozygosity analysis of benign, atypical, and anaplastic meningiomas

OBJECTIVE

Up to 70% of typical meningiomas demonstrate allelic loss at chromosome 22q. Allelic loss at additional chromosomal loci is associated with atypia and anaplasia in meningiomas. The pattern of allelic loss or loss of heterozygosity (LOH) follows a nonrandom, multistep pattern.

METHODS

All surgical meningioma samples obtained from 1991 to 1992 at the University of Pittsburgh Medical Center were analyzed according to current World Health Organization criteria. Samples without constitutional deoxyribonucleic acid (DNA) were excluded from this analysis. Individual hematoxylin and eosin slides from 43 patients were microdissected, and the DNA was harvested and amplified in the presence of 24 pairs of polymerase chain reaction primers, representing 24 microsatellite loci. The polymerase chain reaction products were subjected to capillary gel electrophoresis and a fluorescence-based DNA analysis system. LOH was defined as ratios of allelic peak heights falling within a conservative threshold of less than 0.5 or more than 2.0. Fisher's exact test and receiver operator characteristic curves were used to test the relationship between benign versus atypical and malignant pathological features and LOH at specific loci or combinations of loci.

RESULTS

On review by two independent pathologists, 34 benign meningiomas, 6 atypical meningiomas, and 3 anaplastic meningiomas were identified. The mean number of alleles with LOH was 1.5 +/- 1.2 for benign meningiomas, 6.7 +/- 2.7 for atypical meningiomas, and 8.3 +/- 2.3 for anaplastic meningiomas (P < 0.001). The most important individual loci to predict malignancy were D1S407 (P = 0.006), L-myc (P < 0.001), D10S520 (P = 0.003), D10S1173 (P = 0.042), D11S1920 (P < 0.001), D14S555 (P = 0.041), D17S1289 (P < 0.001), D22S417 (P = 0.001), D22S431 (P = 0.019), and D22S532 (P = 0.028). Combining the LOH data across loci, the area under the receiver operator characteristic curve was 0.993, corresponding to virtually perfect prediction of pathological characteristics.

CONCLUSION

Microsatellite marker analysis of allelic loss is a useful method of predicting atypia and anaplasia in meningiomas. More regions of allelic loss are seen in anaplastic and atypical meningiomas as compared with benign meningiomas. This study confirms previously reported chromosomal regions of allelic loss in atypical and anaplastic meningiomas and suggests additional chromosomal regions that may represent heretofore uncharacterized deletions within meningiomas. This type of genetic fingerprint ultimately may serve both a diagnostic and therapeutic role.

Age associated increase in the prevalence of chromosome 22q loss of heterozygosity in histological subsets of benign meningioma

Chromosome 22q loss of heterozygosity (LOH) is the most common allelic loss in benign meningioma and is thought to be the earliest initiating event in meningioma formation. We used published data and logistic regression to evaluate the association of 22q LOH with age at diagnosis in 318 transitional, fibroblastic, and meningothelial meningiomas. After adjustment for anatomical location, the odds ratio of 22q LOH per year of age was >1 in each histological type of meningioma, and was significantly >1 in transitional and fibroblastic meningioma. This finding is compatible with involvement of the neurofibromatosis 2 tumour suppressor gene, NF2, on chromosome 22q in the high incidence of benign meningioma in the elderly.

Comprehensive DNA copy number profiling of meningioma using a chromosome 1 tiling path microarray identifies novel candidate tumor suppressor loci

Meningiomas are common neoplasms of the meninges lining of the central nervous system. Deletions of 1p have been established as important for the initiation and/or progression of meningioma. The rationale of this array-CGH study was to characterize copy number imbalances of chromosome 1 in meningioma, using a full-coverage genomic microarray containing 2,118 distinct measurement points. In total, 82 meningiomas were analyzed, making this the most detailed analysis of chromosome 1 in a comprehensive series of tumors. We detected a broad range of aberrations, such as deletions and/or gains of various sizes. Deletions were the predominant finding and ranged from monosomy to a 3.5-Mb terminal 1p homozygous deletion. Although multiple aberrations were observed across chromosome 1, every meningioma in which imbalances were detected harbored 1p deletions. Tumor heterogeneity was also observed in three recurrent meningiomas, which most likely reflects a progressive loss of chromosomal segments at different stages of tumor development. The distribution of aberrations supports the existence of at least four candidate loci on chromosome 1, which are important for meningioma tumorigenesis. In one of these regions, our results already allow the analysis of a number of candidate genes. In a large series of cases, we observed an association between the presence of segmental duplications and deletion breakpoints, which suggests their role in the generation of these tumor-specific aberrations. As 1p is the site of the genome most frequently affected by tumor-specific aberrations, our results indicate loci of general importance for cancer development and progression.

Chromosomal instability in meningiomas

Approximately 60% of sporadic meningiomas are caused by inactivation of the NF2 tumor suppressor gene on chromosome 22. No causative gene is known for the remaining 40%. Cytogenetic analysis shows that meningiomas caused by inactivation of the NF2 gene can be divided into tumors that show monosomy 22 as the sole abnormality and tumors with a more complex karyotype. Meningiomas not caused by the NF2 gene usually have a diploid karyotype. Here we report that, besides the clonal chromosomal aberrations, the chromosome numbers in many meningiomas varied from one metaphase spread to the other, a feature that is indicative of chromosomal instability. Unexpectedly and regardless of genotype, a subgroup of tumors was observed with an average number of 44.9 chromosomes and little variation in the number of chromosomes per metaphase spread. In addition, a second subgroup was recognized with a hyperdiploid number of chromosomes (average 48.5) and considerable variation in numbers per metaphase. However, this numerical instability resulted in a clonal karyotype with chromosomal gains and losses in addition to loss of chromosome 22 only in meningiomas caused by inactivation of the NF2 gene. In cultured cells of all tumor groups, bi- and multinucleated cells were seen, as well as anaphase bridges, residual chromatid strings, multiple spindle poles, and unseparated chromatids, suggesting defects in the mitotic apparatus or kinetochore. Thus, we conclude that even a benign and slow-growing tumor like a meningioma displays chromosomal instability.

Intratumoral patterns of clonal evolution in meningiomas as defined by multicolor interphase fluorescence in situ hybridization (FISH): is there a relationship between histopathologically benign and atypical/anaplastic lesions?

Meningiomas are cytogenetically heterogeneous tumors in which chromosome gains and losses frequently occur. Based on the intertumoral cytogenetic heterogeneity of meningiomas, hypothetical models of clonal evolution have been proposed in these tumors which have never been confirmed at the intratumoral cell level. The aim of this study was to establish the intratumoral patterns of clonal evolution associated with chromosomal instability in individual patients as a way to establish tumor progression pathways in meningiomas and their relationship with tumor histopathology and behavior. A total of 125 meningioma patients were analyzed at diagnosis. In all cases, multicolor interphase fluorescence in situ hybridization (iFISH) studies were performed on fresh tumor samples for the detection of quantitative abnormalities for 11 different chromosomes. In addition, overall tumor cell DNA content was measured in parallel by flow cytometry. iFISH studies were also performed in parallel on tissue sections in a subset of 30 patients. FISH studies showed that 56 (45%) of the 125 cases analyzed had a single tumor cell clone, all these cases corresponding to histologically benign grade I tumors. In the remaining cases (55%) more than one tumor cell clone was identified: two in 45 cases (36%), three in 19 (15%), and four or more clones in five cases (4%). Overall, flow cytometric analysis of cell DNA contents showed the presence of DNA aneuploidy in 44 of these cases (35%), 30% corresponding to DNA hyperdiploid and 5% to hypodiploid cases; from the DNA aneuploid cases, 35 (28%) showed two clones and 9 (7%) had three or more clones. A high degree of correlation (r >/= 0.89; P < 0.001) was found between FISH and flow cytometry as regards the overall quantitative DNA changes detected with both techniques, the former being more sensitive. Among the cases with chromosome abnormalities, the earliest tumor cell clone observed was frequently characterized by the loss of one or more chromosomes (64% of all meningiomas); loss of either a single chromosome 22 or, less frequently, of a sex chromosome (X or Y) and del (1p) was commonly found as the single initial cytogenetic aberration (30%, 5%, and 5% of the cases, respectively). Interestingly, an isolated loss of chromosome 22 was only found as the initial abnormality in one out of 14 atypical/anaplastic meningiomas, while the same cytogenetic pattern was present in the ancestral tumor cell clone of 32% of the benign tumors. Cytogenetic patterns based on chromosome gains were found in the ancestral tumor cell clone in 4% of the patients, 2% corresponding to tetraploid tumors. Overall, cytogenetic evolution of the earliest tumor cell clones was frequently associated with tetraploidization (31%). Our results show that meningiomas are genetically heterogeneous tumors that display different patterns of numerical chromosome changes, with the presence of more than one tumor cell clone detected in almost half of the cases including all atypical/anaplastic cases. Interestingly, the pathways of intratumoral clonal evolution observed in the benign tumors were different from those observed in atypical/anaplastic meningiomas, suggesting that the latter tumors might not always represent a more advanced stage of histologically benign meningiomas.

TMF/ARA160 is a BC-box-containing protein that mediates the degradation of Stat3

TMF/ARA160 is a Golgi resident protein whose cellular functions have not been conclusively revealed. Herein we show that TMF/ARA160 can direct the proteasomal degradation of the key cell growth regulator - Stat3. TMF/ARA160 was dispersed in the cytoplasm of myogenic C2C12 cells that were grown under low-serum conditions. The cytoplasmic distribution of TMF/ARA160 was accompanied by its transient association with the tyrosine kinase Fer and with Stat3, which underwent proteasomal degradation under those conditions. Moreover, serum deprivation induced the association of ubiquitinated proteins, with the TMF/ARA160 complex. However, TMF/ARA160 did not bind Stat1, whose cellular levels were increased in serum-starved C2C12 cells. Amino-acid sequence analysis identified a BC-box element in TMF/ARA160 that mediated the binding of this protein to elongin C. Ectopic expression of TMF/ARA160 in serum-starved C2C12 cells drove the ubiquitination and proteasomal degradation of Stat3, an effect that was not caused by TMF/ARA160 devoid of the BC-box motif. Thus, the Golgi apparatus harbors a novel BC-box-containing protein that can direct Stat3 to proteasomal degradation. Interestingly, the level of TMF/ARA160 was significantly decreased in malignant brain tumors, implying a suppressive role of that protein in tumor progression.

Chromosomal and genetic aberrations differ with meningioma subtype

Meningioma is one of the most common brain tumors, and a variety of genetic abnormalities have been detected by the Southern blotting, polymerase chain reaction (PCR), fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH) methods. However, these methods detect only a very limited portion of the tumor genome or have a limited mapping resolution. In this study, we used DNA microarray assay, which detects numerous genetic abnormalities and analyzes a global assessment of molecular events in tumor cells. We analyzed genomic DNA from 26 patients with benign meningiomas by GenoSensor Array 300 in order to characterize gene amplifications, gene deletions, and chromosomal information in the whole genome. Loss of chromosome 22q was found most frequently. This chromosomal aberration was detected in 14 meningiomas (53.8%), particularly in transitional and fibrous meningiomas. In meningothelial meningiomas, amplification of INS and TCL1A was detected more frequently than in other meningioma subtypes. DNA microarray assay revealed new genetic differences among the meningioma subtypes, thus indicating that this novel technique is useful for understanding tumor genesis and for the diagnosis of meningioma subtype.

Malignant progression in meningioma: documentation of a series and analysis of cytogenetic findings

Object. The malignant progression of benign tumors is well documented in gliomas and other systemic lesions. It is also well known that some meningiomas become progressively aggressive despite their original benign status. The theory of clonal evolution is widely believed to explain malignant progression in meningioma; however, the data used to explain stepwise progression have typically been derived from the cytogenetic analysis of different types of tumors of different grades and in different patients. In this study, the authors examined the data obtained in a group of patients with meningiomas that showed clear histopathological progression toward a higher grade of malignancy and then analyzed the underlying cytogenetic findings.

Methods. Among 175 patients with recurrent meningiomas, 11 tumors showed a histopathological progression toward a higher grade that was associated with an aggressive clinical course. Six tumors progressed to malignancy and five to the atypical category over a period averaging 112 months. Tests for MIB-1 and p53 and cytogenetic studies with the fluorescence in situ hybridization (FISH) method were performed in successive specimens obtained in four patients.

The MIB-1 value increased in subsequent samples of tumors. Cytogenetic analysis with FISH showed deletions of 22, 1p, and 14q. In all but one case, these aberrations were also present in the previous specimen despite its lower hispathological grade.

Conclusions. The authors documented the progression of meningiomas from benign to a higher histological grade. These tumors were associated with a complex karyotype that was present ab initio in a histologically lower-grade tumor, contradicting the stepwise clonal evolution model. Although it was limited to the tested probes, the FISH method appears to be more accurate than the standard cytogenetic one in detecting these alterations. Tumors that present with complex genetic alterations, even those with a benign histological grade, are potentially aggressive and require closer follow up.

Meningioma pathology, genetics, and biology

Over the past 5 to 10 years, important advances were made in the understanding of meningioma biology. Progress in molecular genetics probably represents the most important accomplishment in the comprehensive knowledge of meningioma pathogenesis. Several genes could be identified as targets for mutation or inactivation. Additional chromosomal regions were found to be commonly deleted or amplified, suggesting the presence of further tumor suppressor genes or proto-oncogenes, respectively, in these regions. Histopathologically, the most important innovation is represented by the revised WHO classification in the year 2000. Meningioma grading criteria in the new classification scheme are more precise and objective, and should thus improve consistency in predicting tumor recurrence and aggressive behavior. This review focuses mainly on the advances in molecular biology that were achieved in recent years. It summarizes the most important aspects of meningioma classification as the basis to place biological observations into a correlative context, and, further, includes mechanisms of angiogenesis and edema formation as well as the role of hormone receptors in meningiomas.

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

Meningiomas are usually benign tumors; however, they can recur after surgical resection and occasionally show histologic progression to a higher grade II and III malignancy. The second most frequently reported genetic abnormality after 22q loss is deletion of 1p, although alterations in 9q, 10q, and 14q are also implicated in meningioma progression. Fourteen tumors comprising six benign, four atypical, and four malignant meningiomas were examined by means of cytogenetic and fluorescence in situ hybridization analysis. All tumors showed losses in different regions of 1p, with 1p11, 1p13, 1p21, 1p22, 1p32, and 1q21 breakpoints; eight tumors also presented alterations of chromosome 14. Five of the six cases with deletions on 1p and normal chromosome 14 were grade I, and two were recurrent. All but one of the eight cases with simultaneous 1p deletion and alterations of chromosome 14 were grade II (3 cases) and grade III (4 cases); all the grade III cases were recurrent. These results support the possible association between changes in 1p and chromosome 14 with the evolution of aggressive meningiomas through tumor progression.

New classification scheme for the prognostic stratification of meningioma on the basis of chromosome 14 abnormalities, patient age, and tumor histopathology

PURPOSE

Meningiomas are usually considered benign tumors. However, relapses occur in 10% to 20% of all patients, including both histopathologically aggressive and benign tumors. This study explored the value of numerical abnormalities for 10 different chromosomes in meningiomas for predicting relapse-free survival (RFS).

PATIENTS AND METHODS

This study prospectively analyzed the frequency of numerical abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y in 70 meningioma patients by fluorescence in situ hybridization and their relationship with disease characteristics at diagnosis and patients' outcome.

RESULTS

Results showed the presence of numerical abnormalities for one or more chromosomes in most patients (77%). Chromosome 22 in the whole series and chromosome Y in males were those more frequently altered, followed by chromosomes 1, 14, and X in females. Patients with abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, the sex chromosomes, and gains of chromosome 22 were associated with adverse prognostic features, more frequent relapses, and shorter RFS. Multivariate analysis showed that tumor grade together with chromosome 14 status and age were the best combination of independent variables for predicting RFS. According to these variables, all patients with a score of two or more than two adverse prognostic factors had experienced relapse at 5 years, whereas none of those with a score of zero had experienced relapse 10 years after surgery.

CONCLUSION

In addition to age and histologic grade, abnormalities of chromosome 14 contribute to a better prognostic stratification of meningioma patients at diagnosis. Additional prospective studies in larger series of patients, also including larger numbers of patients who experienced relapse, are necessary to confirm the utility of the proposed predictive model.

Detection of chromosomal imbalances in spinal meningiomas by comparative genomic hybridization

Little is known about genetic mutations during the malignant progression of spinal meningiomas. This study investigated genomic changes across the entire genome in spinal meningioma samples to determine possible mechanism(s) of tumorigenesis. Paraffin-embedded tissue sections of 16 spinal meningiomas were analyzed by the comparative genomic hybridization (CGH) technique. Lymphocytes of the patients were evaluated as controls. Genomic change was detected in 11 samples. Complete or partial loss of chromosome 22 was the most commonly seen abnormality in eight cases. Chromosome losses on 1p, 9p, and 10q and gains on 5p and 17q were the other abnormalities. These changes are all frequently seen in meningiomas, but are mostly specific to atypical and anaplastic meningiomas. However, in the present study, copy number changes on chromosomes 9p (3 samples), 17q (2 samples), and 1p (2 samples) were seen even in the benign tumors. Our results suggest that in addition to the neurofibromatosis type 2 tumor suppressor gene, other cancer-related genes located on 1p, 9p, 10q, and 17q might be involved in the etiology of spinal meningiomas.

Histologically benign metastatic meningioma: morphological and cytogenetic study. Case report

The authors report on a 75-year-old man with histologically benign fibroblastic meningioma metastasizing to the lung, liver, spleen, and kidney. The original tumor exhibited a complex karyotype involving different structural and numerical anomalies associated with monosomy of chromosome 22. The implication of chromosome 1p36 was confirmed by fluorescence in situ hybridization in most interphase nuclei. Metastases occurred 4 months after incomplete resection with prior therapeutic embolization. The recurrent tumor in turn displayed anaplastic features and an increased Ki-67 labeling index. Genetic alterations in such morphologically benign meningiomas have been implicated in the malignant development and progression of these tumors.

Meningioma: Un modelo de evolución citogenética en la iniciación y progresión tumoral

Meningiomas are tumors of the central nervous system with a great morphological heterogeneity. They are generally benign, and have the capacity to progress to a higher histological grade (atypical and anaplastic), which is associated with an increase in biological aggressivity and/or capacity to recur. Citogenetically this evolution is characterized by total or partial monosomy 22 in the early phase, continued by numerical and structural changes during tumor progression. In this study, we present a review of 85 cases of meningiomas: 43 benign, 28 atypical and 14 anaplastic. We study the clinical and histopathological features, and their correlation with cytogenetie abnormalities present in these tumors. Numerical aberrations such as monosomy of chromosome 10, 14 and 18, and structural abnormalities such as deletions on 1p are directly associated with a higher agressivity of tumors. An association of aberatons on 1p and chromosome 14 are more commonly found in atypical and anaplastic meningiomas. These facts imply that the presence of complex karyotypes progressively increases from grade I to grade III meningiomas. Furthermore, these karyotypes are common in recurrent tumors.

Incidence of numerical chromosome aberrations in meningioma tumors as revealed by fluorescence in situ hybridization using 10 chromosome-specific probes

OBJECTIVE

Although information on the cytogenetic characteristics of meningioma tumors has accumulated progressively over the past few decades, information on the genetic heterogeneity of meningiomas is still scanty. The aim of the present study was to analyze by interphase fluorescence in situ hybridization (FISH) the incidence of numerical abnormalities for chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y in a group of 70 consecutive meningioma tumors. Another goal was to establish the potential associations among the altered chromosomes, as a way to assess both intertumoral and intratumoral heterogeneity.

METHODS

For the purpose of the study, 70 patients diagnosed with meningioma were analyzed. Interphase FISH for the detection of numerical abnormalities for chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y was applied to fresh tumor samples from each of the patients studied.

RESULTS

The overall incidence of numerical abnormalities was 76%. Chromosome Y in males and chromosome 22 in the whole series were the most common abnormalities (46% and 61%, respectively). Despite the finding that monosomy of chromosome 22/22q(-) deletions are the most frequent individual abnormality (53%), we have observed that chromosome gains are significantly more common than chromosome losses (60% versus 40%). Chromosome gains corresponded to abnormalities of chromosomes 1 (27%), 9 (25%), 10 (23%), 11 (22%), 14 (33%), 15 (22%), 17 (23%), and X in females (35%) and males (23%) whereas chromosome losses apart from chromosome 22 frequently involved chromosomes 14 (19%), X in males (23%), and Y in males (32%). Although an association was found among most gained chromosomes on one side and chromosome losses on the other side, different association patterns were observed. Furthermore, in the latter group, monosomy 22/22q(-) was associated with monosomy X in females and monosomy 14/14q(-) was associated with nulisomy Y in males. In addition, chromosome losses usually involved a large proportion of the tumor cells whereas chromosome gains were restricted to small tumor cell clones, including tetraploid cells.

CONCLUSIONS

Our results show that meningiomas are genetically heterogeneous tumors that display different patterns of numerical chromosome changes, as assessed by interphase FISH.

Evaluation of relationship between chromosome 22 and p53 gene alterations and the subtype of meningiomas by the interphase-FISH technique

In this study, we investigated the relationship between genetic alterations such as chromosome 22 aneuploidy and p53 gene deletion, and the pathological types of meningioma of typical and aggressive forms. Thirty-four meningiomas (23 typical and 11 aggressive) were examined by application of fluorescence in situ hybridization (FISH) with chromosome 22 specific alpha satellite probe and a combination of p53 locus specific and chromosome 17 centromere specific alpha satellite probes, to evaluate the chromosome 22 aneuploidy and gain or loss of p53 gene along with chromosome 17. The results showed that, although chromosome 22 aneuploidy was seen in 7 out of 23 typical (30.4%) and 4 out of 11 aggressive meningiomas (36.3%), no p53 deletion was detected in typical meningiomas, and p53 deletion was detected in 3 out of 11 aggressive meningiomas (1 atypical and 2 malignant), which had recurrence. There were no simultaneous occurrences of p53 gene deletions between typical and aggressive meningiomas. The present findings indicate that the loss of chromosome 22 may be involved with tumorogenesis of typical and aggressive meningiomas, while p53 gene deletions may be involved with malignant progression and recurrence in the aggressive meningiomas.

Aggressive phenotypic and genotypic features in pediatric and NF2-associated meningiomas: a clinicopathologic study of 53 cases

Pediatric and NF2-associated meningiomas are uncommon and poorly characterized in comparison to sporadic adult cases. In order to elucidate their molecular features, we analyzed MIB-1, progesterone receptor (PR), NF2, merlin, DAL-1, DAL-1 protein, and chromosomal arms 1p and 14q in 53 meningiomas from 40 pediatric/NF2 patients using immunohistochemistry and dual-color fluorescence in situ hybridization (FISH). Fourteen pediatric (42%) patients, including 5 previously undiagnosed patients, had NF2. The remaining 19 (58%) did not qualify. All 7 of the adult patients had NF2. Meningioma grading revealed 21 benign (40%), 26 atypical (49%), and 6 anaplastic (11%) examples. Other aggressive findings included high mitotic index (32%), high MIB-1 LI (37%), aggressive variant histology (e.g. papillary, clear cell) (25%), brain invasion (17%), recurrence (39%), and patient death (17%). FISH analysis demonstrated deletions of NF2 in 82%, DAL-1 in 82%, 1p in 60%, and 14q in 66%. NF2-associated meningiomas did not differ from sporadic pediatric tumors except for a higher frequency of merlin loss in the former (p = 0.020) and a higher frequency of brain invasion in the latter (p = 0.007). Thus, although pediatric and NF2-associated meningiomas share the common molecular alterations of their adult, sporadic counterparts, a higher fraction are genotypically and phenotypically aggressive. Given the high frequency of undiagnosed NF2 in the pediatric cases, a careful search for other features of this disease is warranted in any child presenting with a meningioma.

Anaplastic and atypical meningiomas express high levels of Fas and undergo apoptosis in response to Fas ligation

In this study we characterized the expression of Fas and Fas ligand in different types of meningiomas and examined the effect of Fas ligation on the death of meningioma cells in culture. Using Western blot analysis, we found that extracts derived from anaplastic and atypical meningiomas expressed high levels of Fas, whereas benign meningiomas did not express detectable levels of this protein. All of the meningiomas examined expressed low levels of Fas ligand. Cultures of anaplastic meningiomas also expressed Fas and treatment of these cells with anti-Fas antibody induced cell death. The results of this study indicate that Fas is preferentially expressed in atypical and anaplastic meningiomas and suggest that it is involved in the increased apoptosis observed in these tumors.

Alterations of the tumor suppressor genes CDKN2A (p16(INK4a)), p14(ARF), CDKN2B (p15(INK4b)), and CDKN2C (p18(INK4c)) in atypical and anaplastic meningiomas

We investigated 67 meningothelial tumors (20 benign meningiomas, 34 atypical meningiomas, and 13 anaplastic meningiomas) for losses of genetic information from chromosome arms 1p and 9p, as well as for deletion, mutation, and expression of the tumor suppressor genes CDKN2A (p16(INKa)/MTS1), p14(ARF), CDKN2B (p15(INK4b)/MTS2) (all located at 9p21) and CDKN2C (1p32). Comparative genomic hybridization and microsatellite analysis showed losses on 1p in 11 anaplastic meningiomas (85%), 23 atypical meningiomas (68%), and 5 benign meningiomas (25%). One atypical meningioma with loss of heterozygosity on 1p carried a somatic CDKN2C mutation (c.202C>T: R68X). Losses on 9p were found in five anaplastic meningiomas (38%), six atypical meningiomas (18%), and one benign meningioma (5%). Six anaplastic meningiomas (46%) and one atypical meningioma (3%) showed homozygous deletions of the CDKN2A, p14(ARF), and CDKN2B genes. Two anaplastic meningiomas carried somatic point mutations in CDKN2A (c.262G>T: E88X and c.262G>A: E88K) and p14(ARF) (c.305G>T: G102V and c.305G>A: G102E). One anaplastic meningioma, three atypical meningiomas, and one benign meningioma without a demonstrated homozygous deletion or mutation of CDKN2A, p14(ARF), or CDKN2B lacked detectable transcripts from at least one of these genes. Hypermethylation of CDKN2A, p14(ARF), and CDKN2B could be demonstrated in one of these cases. Taken together, our results indicate that CDKN2C is rarely altered in meningiomas. However, the majority of anaplastic meningiomas either show homozygous deletions of CDKN2A, p14(ARF), and CDKN2B, mutations in CDKN2A and p14(ARF), or lack of expression of one or more of these genes. Thus, inactivation of the G(1)/S-phase cell-cycle checkpoint is an important aberration in anaplastic meningiomas.

Analysis of p73 gene in meningiomas with deletion at 1p

The p73 gene has been mapped to 1p36.33, a chromosome region that is frequently deleted in a wide variety of neoplasms including meningiomas. The protein encoded by p73 shows structural and functional similarities to p53 and may thus represent a candidate tumor suppressor gene. To determine whether p73 is involved in the development of meningiomas, we examined 30 meningioma samples with proven 1p deletion for mutations of p73. Sequence analysis of the entire coding region of the p73 gene revealed previously reported polymorphisms in eight cases. A tumor-specific missense mutation as a result of an A-to-G transition with an Asn204Ser change was found in one meningioma that nevertheless retained the normal allele. These results suggest that if p73 plays a role in meningioma carcinogenesis, it must be in a manner different from the Knudson two-hit model.

NF2 status of meningiomas is associated with tumour localization and histology

In approximately 60% of sporadic meningiomas, the tumour suppressor gene NF2, located on chromosome 22q, is inactivated. Mutations in the NF2 gene have been specifically reported in transitional and fibrous, but not meningothelial, meningiomas. Since meningothelial meningiomas frequently occur in anterior parts of the skull base, the association between tumour localization, size, histological subtype and NF2 status was investigated in a group of 42 sporadic meningiomas. NF2 status was determined by LOH analysis, karyotyping and FISH. Tumour size and site were evaluated by CT scans and MRIs. A strong correlation between tumour localization in the anterior skull base and intact 22q was revealed (p=0.003). On the other hand, tumour localization at the convexity was associated with disruption of NF2 (p=0.023). Furthermore, an association between chromosome 22 status and histological subtype was observed: abnormalities of chromosome 22q were more frequent in transitional and fibrous meningiomas than in the meningothelial variant (p<0.001). Also, the meningothelial meningiomas were more often located in the anterior skull base (p<0.006). Based on these findings, it is concluded that an alternative histogenesis and genetic pathway is likely to exist for meningiomas arising in the anterior skull base.

Chromosome 1p and 14q FISH analysis in clinicopathologic subsets of meningioma: diagnostic and prognostic implications

The second most frequently reported genetic abnormalities in meningiomas after 22q loss are deletions of 1p and 14q. To assess the potential diagnostic and prognostic utility of these chromosomal alterations, we studied 180 well-characterized meningiomas using dual-color fluorescence in situ hybridization (FISH) with DNA probes localized to 1p32, 1p36, 14q13, and 14q32. Our cohort consisted of 77 benign (grade I), 74 atypical (grade II), and 29 anaplastic (grade III) meningiomas. Benign and atypical meningiomas were further stratified into subsets of recurring (despite gross total resection) vs non-recurring (at least 10 yr of follow-up) and mitotically active vs brain invasive subsets, respectively. Losses of 1p and 14q losses were identified in 23% and 31% of benign, 56% and 57% of atypical, and 75% and 67% of anaplastic meningiomas, respectively (p < 0.001 for 1p; p = 0.004 for 14q). Combined 1p/14q deletions were encountered in 7% benign. 39% atypical, and 63% anaplastic meningiomas (p < 0.001). Benign non-recurring meningiomas were less likely to harbor 14q deletions than recurring examples (17% vs 50%, p = 0.013). There was a trend for anaplastic meningiomas with 14q deletions and atypical meningiomas with combined 1p/14q deletions to have poorer overall survivals, though neither reached statistical significance. We conclude that 1p and 14q deletions are highly associated with increasing histologic grade and play an important role in meningioma tumor progression. Furthermore, 14q FISH analysis may aid in assessing recurrence risk in histologically benign meningiomas.

Loss of 1p in recurrent meningiomas

Deletion of 1p is associated with histological progression to meningiomas. Detection of this alteration may be a predicting factor for recurrences in this tumor. We present 8 meningiomas from four patients: the original tumor and the first recurrence in one patient, and the first and second recurrences in the other three were studied. We compared results of monosomy 22 and deletion of chromosome 1p with cytogenetic methods and fluorescence in situ hybridization (FISH) analysis obtained from slides of direct preparations, of cultured cells and slides of touch preparations. The cytogenetic study showed normal chromosome 22 and deletion on 1p32 in both samples of one patient; only monosomy 22 in both recurrences in another patient, and normal karyotypes with different non-clonal anomalies in the other tumors. However, with FISH analysis, monosomy 22 in both recurrences of three patients was demonstrated, as well as the loss of 1p in all tumors. These results were more evident in the analysis of direct and touch preparations than in those of cultured cells.

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

The molecular pathogenesis of meningiomas is poorly characterized. Loss of NF2 (merlin) expression has been reported in 30%-80% of all sporadic meningiomas. Recently, we found that loss of expression for a second Protein 4.1-family tumor suppressor. DAL-1, is also common. A biologically important role for progesterone receptor (PR) has also been proposed based on its reported inverse relationship with tumor grade. In order to better define the pathogenetic roles of these proteins, we studied the merlin, DAL-1, and PR immunoprofiles in 175 fully characterized meningiomas, including nonrecurring versus recurring benign, proliferative versus brain invasive atypical and anaplastic subtypes. Loss of expression for either Protein 4.1-family tumor suppressor (merlin or DAL-1) was almost universal (92%), with combined losses being common (58%). Individually, absence of merlin or DAL-1 protein was detected in 74% and 76% respectively, with no significant differences among the 5 subsets. PR immunoreactivity was commonly associated with retained DAL-1 expression (p < 0.001) and with tumor grade, with 51% of benign, 21% of atypical, and 11% of anaplastic tumors staining positive (p < 0.001). We conclude that PR immunohistochemistry may have diagnostic utility in meningothelial neoplasms. Protein 4.1-family tumor suppressor losses are likely important early events in meningioma pathogenesis, whereas PR expression is associated with benignity.

Structural and numerical aberrations of chromosome 22 in a case of follicular variant of papillary thyroid carcinoma revealed by conventional and molecular cytogenetics

This study reports a case of papillary carcinoma with vesicular components showing multiclonal aberrations of chromosome 22 as revealed by RHG-banding cytogenetics and by fluorescence in situ hybridization (FISH; whole chromosome 22 and BCR-ABL-specific locus probes, multi-FISH). Four clones with chromosome 22 changes as the sole abnormality were seen. The main abnormal clone lacked the whole chromosome 22. A del(22)(q11) was observed in a second group of cells. The third clone had an idic(22). Finally, FISH revealed a fourth abnormal cell population with a der(17)t(?17;22). Some of these chromosome 22 alterations have been described in other solid tumors such as meningiomas and neurinomas, suggesting a common genetic pathway of tumor progression occurring in a multistep process. Chromosome 22 changes do not seem to be involved in pure papillary thyroid tumors and therefore could be related to the maintenance of a follicular-type histological pattern.