A consistent region of deletion on 1p36 in meningiomas: identification and relation to malignant progression

Outcomes following upfront radiation versus monitoring in atypical meningiomas: 16-year experience at a tertiary medical center

Background

The role of postoperative upfront radiotherapy (RT) in the management of gross totally resected atypical meningiomas remains unclear. This single-center retrospective review of newly diagnosed histologically confirmed cases of World Health Organization (WHO) Grade II atypical meningioma at Weill Cornell Medicine from 2004 to 2020 aims to compare overall survival (OS) and progression-free survival (PFS) of postoperative upfront RT versus observation, stratified by resection status (gross total resection [GTR] vs subtotal resection [STR]).

Methods

Ninety cases of atypical meningioma were reviewed (56% women; median age 61 years; median follow-up 41 months).

Results

In patients with GTR, hazard ratio (HR) of PFS was 0.09 for postoperative upfront RT versus observation alone (95% confidence interval [CI] 0.01–0.68; P = .02), though HR for OS was not significant (HR 0.46; 95% CI 0.05–4.45; P = .5). With RT, PFS was 100% at 12 and 36 months (compared to 84% and 63%, respectively, with observation); OS at 36 months (OS36) was 100% (compared to 94% with observation). In patients with STR, though PFS at 36 months was higher for RT arm versus observation (84% vs 74%), OS36 was 100% in both arms. HR was not significant (HR 0.76; 95% CI 0.16–3.5; P = .73).

Conclusions

This retrospective study suggests postoperative upfront RT following GTR of atypical meningioma is associated with improved PFS compared to observation. Further studies are required to draw conclusions about OS.

Concurrent exome-targeted next-generation sequencing and single nucleotide polymorphism array to identify the causative genetic aberrations of isolated Mayer-Rokitansky-Küster-Hauser syndrome

STUDY QUESTION

Can the use of whole-exome sequencing (WES) together with single nucleotide polymorphism (SNP) array help to identify novel causative genes of isolated Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome?

SUMMARY ANSWER

OR4M2 (olfactory receptor, family 4, subfamily M, member 2) and PDE11A (phosphodiesterase 11A) gene loss-of-function variants as well as deletions at 15q11.2, 19q13.31, 1p36.21, and 1q44 were identified as possible commonly altered regions in patients with type 1 MRKH.

WHAT IS KNOWN ALREADY

The isolated form of Müllerian aplasia is the most common subtype of MRKH syndrome, which invariably leads to difficulties producing offspring in affected women. However, there is little information currently available to allow for genetic testing and counseling to be performed for those affected by this syndrome.

STUDY DESIGN, SIZE AND DURATION

This was a case-series genetic study. A total of seven consecutive unrelated women with type 1 MRKH were enrolled. The enrollment and experimental procedures were performed over a 2-year period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Whole exome-targeted next-generation sequencing and SNP array (Affymetrix Genome-Wide Human SNP Array 6.0) were performed on the first five unrelated women with type 1 MRKH syndrome. The data were combined, and the '3-hit principal' was applied on a genome-wide scale to search for the common causative genes. Quantitative PCR (qPCR) and Sanger sequencing were used to validate the identified genomic copy number losses and variants. Replication tests using direct Sanger sequencing and qPCR were performed on the remaining two women with type 1 MRKH syndrome to support the credibility of the potential candidate genes and deletions.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 3443 damaging variants based on WES were shown to intersect with 1336 copy number variations (deletions) derived from the SNP array. Four highly recurrent deletions at 15q11.2 (80%), 19q13.31 (40%), 1p36.21 (40%) and 1q44 (40%) were identified in the first five women with type 1 MRKH syndrome and were considered to be novel candidate aberrations. A previously reported 1q21.1 deletion was also recurrent in two of the first five women with type 1 MRKH syndrome. The 1q44 and 19q13.31 deletions were present in at least one of the two additional patients. Damaging variants were detected in HNRNPCL1 (heterogeneous nuclear ribonucleoprotein C-like 1), OR2T2 (olfactory receptor, family 2, subfamily T, member 2), OR4M2, ZNF816 (zinc finger protein 816), and PDE11A in several of the initial five patients. Among these, the damaging variants of OR4M2 (located at 15q11.2) and PDE11A were found in at least one of the two additional patients with type 1 MRKH.

LIMITATIONS, REASONS FOR CAUTION

In this study, we only searched for the deletions or damaging variants causing loss-of-function of genes in at least three of the initial five patients (3-hit criteria). Therefore, the study was designed to only detect common causative genes. Genomic duplications and/or rare individual mutations that may have also contributed to MRKH syndrome were not investigated.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrated the feasibility of the use of combined data from both WES and SNP arrays for the identification of possible common causative genetic aberrations in patients with type 1 MRKH syndrome on a genome-wide scale. Further validation of our found causative genes is required before applying on genetic testing and counseling.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by grants from the National Science Council of Taiwan (NSC98-2314-B002-105-MY3 and NSC 100-2314-B002-027-MY3). The funding sources had no involvement in the design or analysis of the study. The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Posttranscriptional deregulation of signaling pathways in meningioma subtypes by differential expression of miRNAs

BACKGROUND

Micro (mi)RNAs are key regulators of gene expression and offer themselves as biomarkers for cancer development and progression. Meningioma is one of the most frequent primary intracranial tumors. As of yet, there are limited data on the role of miRNAs in meningioma of different histological subtypes and the affected signaling pathways.

METHODS

In this study, we compared expression of 1205 miRNAs in different meningioma grades and histological subtypes using microarrays and independently validated deregulation of selected miRNAs with quantitative real-time PCR. Clinical utility of a subset of miRNAs as biomarkers for World Health Organization (WHO) grade II meningioma based on quantitative real-time data was tested. Potential targets of deregulated miRNAs were discovered with an in silico analysis.

RESULTS

We identified 13 miRNAs deregulated between different subtypes of benign meningiomas, and 52 miRNAs deregulated in anaplastic meningioma compared with benign meningiomas. Known and putative target genes of deregulated miRNAs include genes involved in epithelial-to-mesenchymal transition for benign meningiomas, and Wnt, transforming growth factor-β, and vascular endothelial growth factor signaling for higher-grade meningiomas. Furthermore, a 4-miRNA signature (miR-222, -34a*, -136, and -497) shows promise as a biomarker differentiating WHO grade II from grade I meningiomas with an area under the curve of 0.75.

CONCLUSIONS

Our data provide novel insights into the contribution of miRNAs to the phenotypic spectrum in benign meningiomas. By deregulating translation of genes belonging to signaling pathways known to be important for meningioma genesis and progression, miRNAs provide a second in line amplification of growth promoting cellular signals. MiRNAs as biomarkers for diagnosis of aggressive meningiomas might prove useful and should be explored further in a prospective manner.

Pathology and genetics of meningiomas

This article constitutes a mini-review of the pathology and genetics of meningiomas. Meningiomas are the most common primary intracranial tumors. They are usually durally based and are often found adjacent to venous sinuses and dural infoldings. The majority of these tumors are WHO grade I, although a minority is WHO grade II, atypical, or WHO grade III, anaplastic. Grade II and III meningiomas show a greater tendency than Grade I tumors to recur and metastasize. The current WHO scheme recognizes 15 histologic subtypes of meningiomas. Nine of these are WHO grade I, three are grade II, and three are grade III. In addition to these histologic subtypes, meningiomas can also be graded on the basis of mitotic activity, evidence of brain invasion, growth pattern cellular density, nuclear atypia, and necrosis. Loss of the long arm of chromosome 22, which is usually associated with inactivation of the NF2 gene, is the most common genetic abnormality found in meningiomas. Other chromosomal abnormalities associated with tumorogenesis and increased gradeof meningiomas include loss of heterozygosity for chromosome 1p, loss of 14q, deletion of 9p21, abnormalities of chromosome 10 and 17q. Telomerase activity increases with meningiomas grade as well. The only proven environmental risk factor for meningiomas is ionizing radiation. Radiation-induced meningiomas are more often multiple and have higher recurrence rates than standard meningiomas.

Slower growth of skull base meningiomas compared with non-skull base meningiomas based on volumetric and biological studies

OBJECT

The precise natural history of incidentally discovered meningiomas (IDMs) remains unknown. It has been reported that for symptomatic meningiomas, tumor location can be used to predict growth. As to whether the same is true for IDMs has not been reported. This study aims to answer this question and provide biological evidence for this assumption by extending the study to involve symptomatic cases.

METHODS

A total of 113 IDMs were analyzed by fine volumetry. A comparison of growth rates and patterns between skull base and non-skull base IDMs was made. Subsequently, materials obtained from 210 patients with symptomatic meningiomas who were treated in the authors' hospital during the same period were included for a biological comparison between skull base and non-skull base tumors using the MIB-1 index.

RESULTS

The 110 patients with IDMs included 93 females and 17 males, with a mean follow-up period of 46.9 months. There were 38 skull base (34%) and 75 non-skull base (66%) meningiomas. Forty-two (37%) did not exhibit growth of more than 15% of the volume, whereas 71 (63%) showed growth. Only 15 (39.5%) of 38 skull base meningiomas showed growth, whereas 56 (74.7%) of 75 non-skull base meningiomas showed growth (p = 0.0004). In the 71 IDMs (15 skull base and 56 non-skull base), there was no statistical difference between the 2 groups in terms of mean age, sex, follow-up period, or initial tumor volume. However, the percentage of growth (p = 0.002) was significantly lower and the doubling time (p = 0.008) was significantly higher in the skull base than in the non-skull base tumor group. In subsequently analyzed materials from 94 skull base and 116 non-skull base symptomatic meningiomas, the mean MIB-1 index for skull base tumors was markedly low (2.09%), compared with that for non-skull base tumors (2.74%; p = 0.013).

CONCLUSIONS

Skull base IDMs tend not to grow, which is different from non-skull base tumors. Even when IDMs grow, the rate of growth is significantly lower than that of non-skull base tumors. The same conclusion with regard to biological behavior was confirmed in symptomatic cases based on MIB-1 index analyses. The authors' findings may impact the understanding of the natural history of IDMs, as well as strategies for management and treatment of IDMs and symptomatic meningiomas.

The significance of Ki-67/MIB-1 labeling index in human meningiomas: a literature study

Histology alone does not always predict the clinical outcome of human meningiomas. Determination of proliferative activity has therefore become an important diagnostic and prognostic tool to identify more aggressive meningiomas, and the Ki-67/MIB-1 monoclonal antibody has become widely used. The aim of this study was to assess the prognostic value of the Ki-67/MIB-1 labeling index (LI) in human meningiomas by a search in the literature. In PubMed/Medline databases, 53 articles were found, and they all showed positive correlations between Ki-67/MIB-1 LI and histological malignancy grade. The average mean labeling indices were 3%, 8%, and 17% for grade I-III meningiomas, respectively. There was, however, considerable overlap of indices between the malignancy groups. Concerning recurrence, meningiomas with a labeling index beyond 4% may indicate an increased relapse rate. Consequently, Ki-67/MIB-1 LI represents a useful predictor of tumor grade and risk of recurrence, however, it must be interpreted cautiously in the individual tumor.

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.

Genomic profiling of atypical meningiomas associates gain of 1q with poor clinical outcome

Atypical meningiomas exhibit heterogeneous clinical outcomes. It is unclear which atypical meningiomas require aggressive multimodality treatment with surgery and radiation therapy versus surgery alone to prevent recurrence. Detailed molecular-genetic characterization of these neoplasms is necessary to understand their pathogenesis and identify clinically relevant genetic markers. Oligonucleotide array comparative genomic hybridization was used to identify frequent genetic alterations in 47 primary atypical meningiomas resected at Massachusetts General Hospital between August 1987 and September 2006. Eighty-five percent of samples exhibited loss of 22q, including the neurofibromatosis type 2 gene. The second most frequent regions of loss were confined to the short arm of chromosome 1, particularly 1p33-p36.2 (70%) and 1p13.2 (64%). Other frequent regions of loss, detected in more than 50% of samples, included 14q, 10q, 8q, 7p, 21q, 19, 9q34, and 4p16. Frequent regions of gain were detected along 1q (59%), 17q (44%), 9q34 (30%), and 7q36 (26%). Univariate marker-by-marker analysis of all frequently identified copy number alterations showed potential correlation between gain of 1q and shorter progression-free survival. Given the heterogeneous treatment outcomes of atypical meningioma, investigation of large-scale and focal genomic alterations in multi-institutional efforts may help clarify molecular-genetic signatures of clinical use.

The mammalian ovary from genesis to revelation

Two major functions of the mammalian ovary are the production of germ cells (oocytes), which allow continuation of the species, and the generation of bioactive molecules, primarily steroids (mainly estrogens and progestins) and peptide growth factors, which are critical for ovarian function, regulation of the hypothalamic-pituitary-ovarian axis, and development of secondary sex characteristics. The female germline is created during embryogenesis when the precursors of primordial germ cells differentiate from somatic lineages of the embryo and take a unique route to reach the urogenital ridge. This undifferentiated gonad will differentiate along a female pathway, and the newly formed oocytes will proliferate and subsequently enter meiosis. At this point, the oocyte has two alternative fates: die, a common destiny of millions of oocytes, or be fertilized, a fate of at most approximately 100 oocytes, depending on the species. At every step from germline development and ovary formation to oogenesis and ovarian development and differentiation, there are coordinated interactions of hundreds of proteins and small RNAs. These studies have helped reproductive biologists to understand not only the normal functioning of the ovary but also the pathophysiology and genetics of diseases such as infertility and ovarian cancer. Over the last two decades, parallel progress has been made in the assisted reproductive technology clinic including better hormonal preparations, prenatal genetic testing, and optimal oocyte and embryo analysis and cryopreservation. Clearly, we have learned much about the mammalian ovary and manipulating its most important cargo, the oocyte, since the birth of Louise Brown over 30 yr ago.

Serial volumetric assessment of the natural history and growth pattern of incidentally discovered meningiomas

OBJECT

Due to advances in neuroimaging and the increasing use of imaging to screen for brain disease ("brain checkups"), meningiomas are now often detected as an incidental finding. The natural history of these asymptomatic meningiomas remains unclear, however. In this study, the authors investigated the natural history and growth pattern of incidentally detected meningiomas using serial volumetric assessment and regression analysis.

METHODS

In 70 patients with incidentally discovered meningiomas who underwent follow-up for longer than 1 year, tumor volumes were calculated volumetrically at each follow-up visit, and tumor growth was determined. In patients with tumor growth, regression analysis was performed to determine the pattern of growth.

RESULTS

Forty-four tumors exhibited growth and 26 did not. In a regression analysis, 16 of the tumors that grew followed an exponential growth pattern and 15 exhibited linear growth patterns. The presence of calcification was the only imaging characteristic that significantly distinguished the group with tumor growth from that without, although no radiological characteristics significantly distinguished the exponential growth group from the linear growth group. Two patients with obvious tumor growth underwent surgical removal and the pathological specimens extracted showed a high proliferative potential.

CONCLUSIONS

The authors found that incidentally discovered meningiomas did not always follow an exponential growth pattern but often exhibited more complex patterns of growth. Serial monitoring of tumor volumes and regression analysis may reveal the growth pattern of incidental meningiomas and provide information useful for determining treatment strategy.

Radiation-induced meningiomas: clinical, cytogenetic, and microarray features

Limited information exists about the clinical and biological features of radiation-induced meningiomas (RIMs), particularly those that follow high-dose therapeutic radiation. We report our experience with 20 patients with RIMs (16 following high-dose radiotherapy) treated at our institution from 1993-2006. Patients (14 female, 6 male) had intervals from first radiotherapy to RIM diagnosis of 11-63 years; 12 had at least one RIM occur at an interval of 30 years or more after initial radiotherapy. Multiple RIMs were seen in six patients, with one patient developing his six RIMs sequentially over a 22-year interval. Most RIMs could be managed surgically, either with a single extensive resection or additional resection(s). Adjuvant stereotactic radiosurgery, external beam radiation, or chemotherapy were required in a minority (n = 6). Most were WHO grade I meningiomas. Complex karyotypes were found in three of four cases and abnormalities of chromosome 1p and/or LOH 1p36 were identified in five of 11 informative cases. Gene-expression microarray analysis of RIMs (n = 5) compared to non-RIMs (MEN, n = 6) and a panel of other tumors (n = 62) showed that RIM gene-expression was similar to that seen in MEN, and by clustering analysis did not separate from them. However, microarray comparative gene-expression analysis did demonstrate a few genes with significant differences in the expression level in RIM versus MEN. Of note, NF2 was under-expressed in four of five RIMs (P = 0.0065), at a similar level as measured in MEN.

Expression of cell adhesion proteins and proteins related to angiogenesis and fatty acid metabolism in benign, atypical, and anaplastic meningiomas

Most meningiomas are benign tumours of arachnoidal origin, although a small number have high proliferative rates and invasive properties which complicate complete surgical resection and are associated with increased recurrence rates. Few prognostic indicators exist for meningiomas and further research is necessary to identify factors that influence tumour invasion, oedema and recurrence. Paraffin sections from 25 intracranial meningiomas were analysed for expression of the proteins vascular endothelial growth factor (VEGF), VEGF receptors Flt1 and Flk1, E-cadherin, metalloproteinases 2 and 9 (MMP2, MMP9), CD44, receptor for hyaluronic acid-mediated motility (RHAMM), hyaluronic acid (HA), CD45, cyclooxygenase 2 (COX2), brain fatty acid binding protein (BFABP), Ki67, and proliferating cell nuclear antigen (PCNA). Correlations among protein expression were found for several markers of proliferation (Ki67, PCNA, MI) and microvessel density (MVD). COX2 expression increased with increasing with tumour grade and correlated with Ki67, PCNA, MI, MVD, and BFABP. BFABP expression also correlated with Ki67 and PCNA expression. Relationships were also identified among angiogenic factors (VEGF, Flt1, Flk1) and proliferation markers. Oedema was found to correlate with MMP9 expression and MMP9 also correlated with proliferation markers. No correlations were found for MMP2, E-cadherin, or CD44 in meningiomas. In conclusion Ki67, PCNA, MI, MVD, BFABP, and COX2 were significantly correlated with meningioma tumour grade and with each other. These findings, by correlating both intracellular fatty acid transport and eicosanoid metabolism with tumour proliferation, as determined by Ki67 labelling and mitotic index, suggest fatty acids are involved in the progression of meningiomas.

Atypical and malignant meningioma: outcome and prognostic factors in 119 irradiated patients. A multicenter, retrospective study of the Rare Cancer Network

PURPOSE

To retrospectively analyze and assess the outcomes and prognostic factors in a large number of patients with atypical and malignant meningiomas.

METHODS AND MATERIALS

Ten academic medical centers participating in this Rare Cancer Network contributed 119 cases of patients with atypical or malignant meningiomas treated with external beam radiotherapy (EBRT) after surgery or for recurrence. Eligibility criteria were histologically proven atypical or anaplastic (malignant) meningioma (World Health Organization Grade 2 and 3) treated with fractionated EBRT after initial resection or for recurrence, and age >18 years. Sex ratio (male/female) was 1.3, and mean (+/-SD) age was 57.6 +/- 12 years. Surgery was macroscopically complete (Simpson Grades 1-3) in 71% of patients; histology was atypical and malignant in 69% and 31%, respectively. Mean dose of EBRT was 54.6 +/- 5.1 Gy (range, 40-66 Gy). Median follow-up was 4.1 years.

RESULTS

The 5- and 10-year actuarial overall survival rates were 65% and 51%, respectively, and were significantly influenced by age >60 years (p = 0.005), Karnofsky performance status (KPS) (p = 0.01), and high mitotic rate (p = 0.047) on univariate analysis. On multivariate analysis age >60 years (p = 0.001) and high mitotic rate (p = 0.02) remained significant adverse prognostic factors. The 5- and 10-year disease-free survival rates were 58% and 48%, respectively, and were significantly influenced by KPS (p = 0.04) and high mitotic rate (p = 0.003) on univariate analysis. On multivariate analysis only high mitotic rate (p = 0.003) remained a significant prognostic factor.

CONCLUSIONS

In this multicenter retrospective study, age, KPS, and mitotic rate influenced outcome. Multicenter prospective studies are necessary to clarify the management and prognostic factors of such a rare disease.

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.

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.

Histological classification and molecular genetics of meningiomas

Meningiomas account for up to 30% of all primary intracranial tumours. They are histologically classified according to the World Health Organization (WHO) classification of tumours of the nervous system. Most meningiomas are benign lesions of WHO grade I, whereas some meningioma variants correspond with WHO grades II and III and are associated with a higher risk of recurrence and shorter survival times. Mutations in the NF2 gene and loss of chromosome 22q are the most common genetic alterations associated with the initiation of meningiomas. With increase in tumour grade, additional progression-associated molecular aberrations can be found; however, most of the relevant genes are yet to be identified. High-throughput techniques of global genome and transcriptome analyses and new meningioma models provide increasing insight into meningioma biology and will help to identify common pathogenic pathways that may be targeted by new therapeutic approaches.

Histopathologic indicators of recurrence in meningiomas: correlation with clinical and genetic parameters

Meningiomas in general are circumscribed slow-growing tumors. However, despite gross total resection, tumor relapse and patients' outcome are still an issue. Risk stratification based on histomorphology alone remains problematic. This study explored the independent prognostic value of potential risk factors among 206 patients who underwent meningioma resection and followed-up until death or a median of 44 months. The statistical analysis considered clinical data, histomorphologic parameters, cytogenetic findings, Ki-67 immunoreactivity, and activity of tissue non-specific alkaline phosphatase (ALPL). Recurrence-free survival estimates were computed and prognostic factors were identified using Cox proportional hazards model. Independent predictors of recurrence included (1) anaplasia; (2) mitotic index > or =20/10 high-power fields; (3) subtotal tumor resection; (4) loss of short arm of chromosome 1 (1p-); and (5) Ki-67 labeling index (LI) >12%. Among totally resected WHO grade I meningiomas, neither histopathologic nor clinical parameters were predictive, whereas 1p- was the only independent prognostic factor. ALPL did not reach significance in the multivariate modeling, however, the fast and low-cost histochemical detection of ALPL expression could be proved as a highly sensitive screening method for 1p-. In particular, biologically aggressive meningiomas of histologically benign or "borderline" phenotype could be therefore identified by ALPL detection followed by 1p in situ hybridization.

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.

GADD45A and EPB41 as tumor suppressor genes in meningioma pathogenesis

Deletions of 1p occur in approximately 30% of meningiomas. Based on loss of heterozygosity (LOH) analysis, two regions on 1p have been suspected to be carriers of tumor suppressor genes. We chose the GADD45A and EPB41 genes as tumor suppressor candidates based on their function and chromosomal localization. We analyzed 19 cases of meningioma with LOH of 1p by means of sequencing of the GADD45A gene and Western blotting of the GADD45a protein. Twenty cases of meningioma without 1p LOH were also analyzed by Western blotting to find out if changes of the GADD45a protein expression occurred. Nineteen samples with 1p LOH (12 grade I; 7 grade II, WHO classification) and 20 samples without 1p LOH (18 grade I; 2 grade II) were also analyzed by means of real-time polymerase chain reaction to find abnormalities in EPB41 mRNA levels in meningioma. LOH analysis was performed using seven microsatellite markers: D1S508 (1p36.2), D1S199 (1p36.1) D1S2734 (1p36.1), D1S2720 (1p34), D1S197 (1p32), D1S162 (1p32), D1S429 (1p11). LOH analysis confirmed previously described localization of putative tumor suppressor genes on 1p and involvement in meningioma pathogenesis (1p36 and 1p32). The open reading frame of GADD45A and intron splicing sites showed neither mutations nor polymorphisms. GADD45a protein molecular weight and expression level were unaltered in meningiomas with and without 1p LOH. We conclude that the GADD45A gene is not involved in meningioma tumorigenesis. EPB41 gene expression was unchanged in all analyzed meningiomas. This suggests that involvement of the EPB41 gene (4.1R protein) in meningioma pathogenesis should be reconsidered.

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.

Distal Chr 4 Harbors a Genetic Locus (Gct1) Fundamental for Spontaneous Ovarian Granulosa Cell Tumorigenesis in a Mouse Model

The spontaneous development of juvenile-onset ovarian granulosa cell tumors in mice of the SWXJ-9 recombinant inbred strain is a model for juvenile-type granulosa cell tumors that appear in very young girls. To expedite gene discovery in this mouse model of childhood cancer, we did a gene mapping study with the SWXJ-9 recombinant inbred strain and the evolutionarily divergent Mus musculus castaneus (CAST/Ei) strain as a mapping partner. Our mapping strategy focused on autosomal determinants of susceptibility with a backcross scheme that exploited a paternal, parent-of-origin effect for a X-linked gene (Gct4) that strongly supports granulosa cell tumor development. Of 1,968 backcross females examined, we detected 81 granulosa cell tumor-bearing animals and compared their allelic inheritance patterns to non-tumor-bearing siblings in a case-control analysis. The results of our study have confirmed an important locus on mouse chromosome (Chr) 4 (Gct1) and have revealed new loci for granulosa cell tumor susceptibility (Gct7-Gct9) on Chrs 1, 2, and 13 with susceptibility alleles contributed by the SWXJ-9 progenitor. Two novel gene-gene interactions supportive for granulosa cell tumor development were also observed between loci on Chrs 17 and 18 and loci on Chrs 2 and 10. Our data substantiate the evidence that Gct1 on Chr 4 is a fundamental oncogene for granulosa cell tumorigenesis in mice and has identified additional interacting autosomal loci that support tumor development.

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.

Meningiomas

Meningiomas are by far the most common tumours arising from the meninges. Progressive enlargement of the tumour leads to focal or generalised seizure disorders or neurological deficits caused by compression of adjacent neural tissue. Surgery remains the primary treatment of choice, although the use of fractionated radiotherapy or stereotactic single-dose radiosurgery is increasing for meningiomas that are incompletely excised, surgically inaccessible, or recurrent and either atypical or anaplastic. Although most meningiomas have good long-term prognosis after treatment, there are still controversies over management in a proportion of cases. We review various features of meningioma biology, diagnosis, and treatment and provide an overview of the current rationale and evidence base for the various therapeutic approaches.

Methylation status of TP73 in meningiomas

Deletions at 1p are frequent in meningioma and represent a genetic marker associated with the genesis of atypical WHO grade II forms. Previous mutational analysis of TP73, a structurally and functionally TP53 homologous gene located at 1p36.33, failed to demonstrate a significant rate of sequence variations linked to gene inactivation in meningiomas with 1p loss. As an alternative, TP73 may be inactivated through aberrant 5' CpG island methylation, a primary mechanism participating in the inactivation of tumor suppressor genes during tumorigenesis. We determined the methylation status of the TP73 gene in a series of 60 meningiomas (33 grade I, 24 grade II, and 3 grade III samples), including tumors with deletion at 1p (n=30) and with intact 1p (n=30). Aberrant methylation was detected in 10 cases (33%) with 1p deletion and in 3 tumors (10%) with retention of alleles at this chromosome arm. The distribution of the 13 cases of methylation according to malignancy grade was 7 grade I, 5 grade II, and 1 grade III tumor. Accordingly, although TP73 aberrant methylation was more frequent in meningiomas with 1p deletion (P<0.05), no association with the grade of malignancy could be established. These findings, together with the previously reported increased TP73 expression in malignant meningiomas suggest that opposing functions of this gene may characterize distinct subsets of tumors: suppressed or reduced expression as a result of CpG methylation in some grade I-grade II tumors, and enhanced expression in some more malignant forms.

Prognostic value of allelic losses and telomerase activity in meningiomas

OBJECT

The goal of this study was to examine allelic losses and telomerase activity in meningiomas to determine whether they could be used to predict disease recurrence.

METHODS

To identify predictive markers of recurrence, a cohort of high-grade (24 World Health Organization [WHO] Grade II and six WHO Grade III) and low-grade (21 WHO Grade I) meningiomas was investigated for losses of heterozygosity (LOHs) on chromosomes 1p, 9p, 10q, 14q, and 22q, a deletion of CDKN2A, and telomerase activity. Results of molecular analyses were compared with radiological and histological findings and progression-free survival (PFS). Losses of heterozygosity on chromosomes 22q, 1p, and 10q, as well as telomerase activity were related to the WHO histological grades of the lesions (p < 0.01, p < 10(-5), p < 10(-4), and p = 0.002, respectively). In the absence of an LOH on 22q, the other alterations were found infrequently. Overall, the number of molecular alterations was closely related to the histological grades of the lesions (p < 10(-6)). An LOH on 22q occurred much more frequently in convexity or falx (33 [87%] of 38 lesions) than in skull base or spinal meningiomas (four [31%] of 13 lesions) (p < 0.001). The histological grade; Simpson grade; an LOH on chromosome 1p, 9p, or 10q; and telomerase activity were correlated with a shorter PFS time (p < 10(-4), p = 0.02, p = 0.000365, p = 0.022, p = 0.00027, and p = 0.000512, respectively).

CONCLUSIONS

On the basis of these data the authors suggest that LOH analysis and a telomerase activity assay could be useful to determine molecular predictors of outcome in patients with meningiomas.

Correlation between genetic alteration and long-term clinical outcome of patients with oligodendroglial tumors, with identification of a consistent region of deletion on chromosome arm 1p

BACKGROUND

In oligodendroglial tumors, allelic losses on chromosome arms 1p and 19q are not only diagnostic molecular markers but also statistically significant predictors of both chemosensitivity and longer recurrence-free survival. In the current study, the authors attempted to analyze 21 patients genetically and clinically, with special emphasis on the correlation between genetic alterations and long-term therapeutic results.

METHODS

The authors reviewed the clinical cases of 21 patients who had undergone surgery for oligodendroglial tumors (13 oligodendrogliomas, World Health Organization [WHO] Grade II; 3 anaplastic oligodendrogliomas, WHO Grade III; 3 oligoastrocytomas, WHO Grade II; and 2 anaplastic oligoastrocytomas, WHO Grade III). Genetic testing for 1p deletions was performed using fluorescence in situ hybridization, and testing for 1p, 17p, and 19q deletions was carried out by microsatellite analysis. Survival was analyzed with univariate and multivariate Cox regression models. In addition, a high-resolution deletion map of 1p, which led to the discovery of a new deleted region on 1p, was obtained.

RESULTS

Statistical analysis revealed that both loss of 1p and loss of 19q independently and significantly predicted overall survival. A high-resolution deletion map, which displayed unusually narrow deletions, revealed a new region of deletion between D1S513 and D1S458 (1p34.3-36.11).

CONCLUSIONS

One of the putative tumor suppressor loci exists more proximally than ever reported. Based on the observation that 1p and 19q deletions predicted survival, the authors suggest further use of diagnostic and prognostic genetic testing in the clinical setting.