Human Meningiomas Research Articles

Therapeutic Potential of HSP90 Inhibition for Neurofibromatosis Type 2

The growth and survival of neurofibromatosis type 2 (NF2)-deficient cells are enhanced by the activation of multiple signaling pathways including ErbBs/IGF-1R/Met, PI3K/Akt, and Ras/Raf/Mek/Erk1/2. The chaperone protein HSP90 is essential for the stabilization of these signaling molecules. The aim of the study was to characterize the effect of HSP90 inhibition in various NF2-deficient models. We tested efficacy of the small-molecule NXD30001, which has been shown to be a potent HSP90 inhibitor. The antiproliferative activity of NXD30001 was tested in NF2-deficient cell lines and in human primary schwannoma and meningioma cultures in vitro. The antitumor efficacy of HSP90 inhibition in vivo was verified in two allograft models and in one NF2 transgenic model. The underlying molecular alteration was further characterized by a global transcriptome approach. NXD30001 induced degradation of client proteins in and suppressed proliferation of NF2-deficient cells. Differential expression analysis identified subsets of genes implicated in cell proliferation, cell survival, vascularization, and Schwann cell differentiation whose expression was altered by NXD30001 treatment. The results showed that NXD30001 in NF2-deficient schwannoma suppressed multiple pathways necessary for tumorigenesis. HSP90 inhibition showing significant antitumor activity against NF2-related tumor cells in vitro and in vivo represents a promising option for novel NF2 therapies.

EMMPRIN expression positively correlates with WHO grades of astrocytomas and meningiomas

High-grade primary brain tumors possessed poor outcome due to invasiveness. Extracellular matrix metalloproteinase inducer (EMMPRIN) stimulates peri-tumoral fibroblasts to secrete matrix metalloproteinase and promote invasiveness. This study hypothesized that high-grade brain tumors overexpress EMMPRIN. Analyzing the public delinked database from the Gene Expression Omnibus profile, the results showed that the EMMPRIN mRNA level was higher in WHO grade IV (n = 81) than in grade III (n = 19, p < 0.0005) astrocytomas and non-tumor brain tissue controls (n = 23, p < 0.00001). The results of tissue microarray-based immunohistochemical (IHC) staining revealed that EMMPRIN levels positively correlated with WHO grades for astrocytomas (p = 0.008) and meningiomas (p = 0.048). EMMPRIN mRNA levels in conventional glioma cell lines (n = 36) was not less than those in glioma primary culture cells (n = 27) and glioblastoma stem-like cells (n = 12). The GBM8401, U87MG, and LN229 human glioma cell lines also overexpressed EMMPRIN. Hematoxylin and eosin, IHC, and immunofluorescence staining of xenografts confirmed that high-grade brain tumors overexpressed EMMPRIN. Lastly, Kaplan–Meier analysis revealed poorer survival in WHO grade IV (n = 56) than in grade III astrocytomas (n = 21, by log-rank test; p = 0.0001, 95 % CI: 1.842–3.053). However, in high-grade astrocytomas, there was no difference in survival between high and low EMMPRIN mRNA levels. Thus, this study identified that high-grade brain tumors overexpress EMMPRIN, which positively correlates with WHO grades in human astrocytomas and meningiomas, and suggests that EMMPRIN may be a therapeutic target of brain tumor.

Alteration of the p53 and Rb tumor suppressor pathways by p16/INK4a and p14/ARF promoter methylation and loss of protein expression in recurrent and nonrecurrent meningiomas.

2064 Background: Promoter methylation inactivates tumor suppressor genes (TSG). The INK4a/ARF locus encodes p16INKa and p14ARF cell cycle regulatory proteins, which control Rb and p53 TSG pathways. Most meningiomas are slow growing tumors, but in spite of complete surgical removal, the recurrence rate at 5 years is 5%, rising to 19% in long-term follow-up. However, there are no markers predictive of this evolution. Epigenetic changes in low-grade meningiomas have not been previously addressed. To get insights into the possible role of p16INK4a and p14ARF TSG alterations in grade 1 meningiomas, we study the methylation status and protein expression of these genes in 140 specimens of meningiomas: 29 nonrecurrent and 57 recurrent in one, two or three times. Methods: Methylation specific PCR and bisulfate modification followed by bisulfate genomic sequencing of CpG islands and staining with p16INKa and p14ARF antibodies (Ab’s). Results: Our data show p16INK4a and p14ARF methylation in 43.4% and14.2% meningiomas respectively. Methylation of p16INK4a is found in a similar proportion in non-recurrent meningiomas (37.9%) and the first biopsy of recurrent cases (38.8%) and increases to a 52.3% in successive biopsies of recurrent cases. Methylation of p14ARF occurs in 13.8% of nonrecurrent vs. 9.6% recurrent meningiomas (first biopsy) and 19.6% of successive recurrent meningiomas. Loss of p16INK4a and p14ARF protein expression was shown in 52.7% and 18.6% of meningiomas respectively. p16INK4a and p14ARF methylation was associated with loss of protein expression in 54.7% and 18.8% of meningiomas. Loss of p16INK4a and p14ARF expression was associated with unmethylated promoters in 52.9% and 17.6% of cases respectively. Conclusions: Epigenetic changes of p16INK4a and p14ARF genes and loss of protein expression leading to Rb and p53 TSG pathways alterations, may have a pathogenic role in human meningiomas. Loss of p16INK4a and p14ARF protein expression associated with unmethylated promoters, could be due to loss of heterozigosity or gen mutation. Increase of p16INK4a and p14ARF methylation along the following biopsies of recurrent cases suggests a possible role of methylation in tumor progression.

Vaccination for invasive canine meningioma induces in situ production of antibodies capable of antibody-dependent cell-mediated cytotoxicity.

Malignant and atypical meningiomas are resistant to standard therapies and associated with poor prognosis. Despite progress in the treatment of other tumors with therapeutic vaccines, this approach has not been tested preclinically or clinically in these tumors. Spontaneous canine meningioma is a clinically meaningful but underutilized model for preclinical testing of novel strategies for aggressive human meningioma. We treated 11 meningioma-bearing dogs with surgery and vaccine immunotherapy consisting of autologous tumor cell lysate combined with toll-like receptor ligands. Therapy was well tolerated, and only one dog had tumor growth that required intervention, with a mean follow up of 585 days. IFN-γ-elaborating T cells were detected in the peripheral blood of 2 cases, but vaccine-induced tumor-reactive antibody responses developed in all dogs. Antibody responses were polyclonal, recognizing both intracellular and cell surface antigens, and HSP60 was identified as one common antigen. Tumor-reactive antibodies bound allogeneic canine and human meningiomas, showing common antigens across breed and species. Histologic analysis revealed robust infiltration of antibody-secreting plasma cells into the brain around the tumor in posttreatment compared with pretreatment samples. Tumor-reactive antibodies were capable of inducing antibody-dependent cell-mediated cytotoxicity to autologous and allogeneic tumor cells. These data show the feasibility and immunologic efficacy of vaccine immunotherapy for a large animal model of human meningioma and warrant further development toward human trials.

Curcumin acts anti-proliferative and pro-apoptotic in human meningiomas

Meningiomas, the most frequent benign intracranial and intraspinal types of tumors are normally removed by surgery. Complications can occur when the tumor is critically localized and cannot be completely removed or when comorbidities of the mostly elder patients increase the general surgical risk. Thus, alternate medical treatment concepts for the therapy of meningiomas would be desirable. Curcumin, the active ingredient of the spice plant Curcuma longa has shown anti-tumorigenic actions in many different types of tumors and therefore, its effect on growth and apoptosis of meningioma cells was studied in the present paper. In vitro, treatment of the human Ben-Men-1 meningioma cell line and of a series of 21 primary human meningioma cell cultures with curcumin (1-20 μM) strongly reduced the proliferation in all cases in a dose dependent manner. Cell cycle analysis by fluorescence-activated cell sorting showed growth arrest at G2/M phase, which was confirmed by demonstrating the corresponding modulation of proteins involved in G2/M arrest by immunoblotting and/or confocal laser microscopy. High dosages (20, 50 μM) of curcumin induced a significant increase of apoptosis in Ben-Men-1 and primary meningioma cell cultures as demonstrated by morphological changes of cell nuclei, DNA fragmentation, translocation of cell membrane associated phosphatidyl serine and the induction of apoptotic-acting cleaved caspase-3. Our results suggest that the multi-targeting drug curcumin has potent anti-tumorigenic actions in meningioma cells and might therefore be a putative candidate for the pharmacological treatment of meningiomas.

Unusual Features in Four Canine Meningiomas

Several subtypes of canine meningioma are recognized. This report describes four canine meningiomas with previously unreported features. The four affected dogs were of different breeds. Three of the affected dogs were male and aged 7-10 years. In one dog, age and gender were not recorded. Meningiomas were located intracranially (three dogs) or within the vertebral canal (one dog). Two meningiomas resembled gemistocytic astrocytomas, while one had focal features of a rhabdoid tumour; these three meningiomas also contained amyloid deposits. The fourth tumour, a secretory meningioma, was rich in amianthoid fibres (i.e. unusual collagen deposits containing giant collagen fibres). All of these features are also described in human meningiomas.

Expression of CD163 prevents apoptosis through the production of granulocyte colony-stimulating factor in meningioma

CD163 is a 130-kDa transmembrane protein expressed in human monocytes and macrophages, and the aberrant expression of CD163 in breast and colorectal cancer associated with patients' poor prognosis was reported. Here, we analyzed the expression of CD163 in meningioma, a common intracranial tumor, and its molecular mechanism in association with meningioma progression. First, we performed immunohistochemical analysis using 50 human meningioma specimens. Next, we established CD163-overexpressing human meningioma cell lines and investigated its roles in tumor progression in vitro and in vivo. Immunohistochemically, 26 of 50 human meningioma specimens (52.0%) were positive for CD163 in tumor cells, including benign grade I (48.5%) and grade II (71.4%) cases. Furthermore, CD163 expression was correlated with histological atypical parameters that directly predict the prognosis of meningioma. CD163-overexpressing meningioma cells showed significant suppression of apoptosis and accelerated tumor growth in nude mice. In addition, unexpected splenomegaly affiliated with the xenograft predicted tumor-derived granulocyte colony-stimulating factor (G-CSF) production, which was confirmed by reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay. To our knowledge, this is the first report that demonstrates CD163 expression in meningioma not only by immunohistochemistry but also by reverse-transcription polymerase chain reaction, using primary culture cells, and provides the novel molecular function of CD163 to prevent apoptosis through the production of G-CSF in meningioma.

Expression of RACGAP1 in high grade meningiomas: a potential role in cancer progression

Recently, Rac GTPase-activating protein 1 (RACGAP1) has been shown to have a critical role in various tumors. The aim of the present study was to investigate the expression of RACGAP1 in human meningiomas and to compare these results with the clinicopathological parameters. Thirty-two cases, classified as 13 World Health Organization grade I (40.6 %), 10 grade II (31.3 %) and 9 grade III (28.1 %) primary meningiomas, were selected from our pathological files. Clinico-pathological data, including survival data, were also available. RACGAP1 expression in the meningiomas was measured by real-time quantitative PCR and western blot. Our results showed the level of RACGAP1 expression in grade III meningioma is higher than that of grade I. Higher levels of RACGAP1 mRNA were significantly correlated with tumor size, higher Simpson grade, histological type and clinical course (P < 0.05). Furthermore, the level of RACGAP1 expression mRNA was positively correlated with MIB-1 labeling index in different meningiomas tissue (r(2) = 0.3237, P = 0.0007). Additionally, Kaplan-Meier curves demonstrated a significantly worse survival in patients with high levels of RACGAP1 mRNA (P = 0.008). In conclusion, these findings suggest that RACGAP1 may be used as a potential predictor for tumor proliferative and patient prognosis in meningiomas.

Telomerase activity in human brain tumors: astrocytoma and meningioma.

Somatic cells do not have telomerase activity but immortalized cell lines and more than 85% of the cancer cells show telomerase activation to prevent the telomere from progressive shortening. The activation of this enzyme has been found in a variety of human tumors and tumor-derived cell lines, but only few studies on telomerase activity in human brain tumors have been reported. Here, we evaluated telomerase activity in different grades of human astrocytoma and meningioma brain tumors. In this study, assay for telomerase activity performed on 50 eligible cases consisted of 26 meningioma, 24 astrocytoma according to the standard protocols. In the brain tissues, telomerase activity was positive in 39 (65%) of 50 patients. One sample t test showed that the telomerase activity in meningioma and astrocytoma tumors was significantly positive entirely (P<0.001). Also, grade I of meningioma and low grades of astrocytoma (grades I and II) significantly showed telomerase activity. According to our results, we suggest that activation of telomerase is an event that starts mostly at low grades of brain including meningioma and astrocytoma tumors.

Adoptive transfer of genetically modified Wilms' tumor 1–specific T cells in a novel malignant skull base meningioma model

Meningiomas are the most commonly diagnosed primary intracranial neoplasms. Despite significant advances in modern therapies, the management of malignant meningioma and skull base meningioma remains a challenge. Thus, the development of new treatment modalities is urgently needed for these difficult-to-treat meningiomas. The goal of this study was to investigate the potential of build-in short interfering RNA-based Wilms' tumor protein (WT1)-targeted adoptive immunotherapy in a reproducible mouse model of malignant skull base meningioma that we recently established. We compared WT1 mRNA expression in human meningioma tissues and gliomas by quantitative real-time reverse-transcription polymerase chain reaction. Human malignant meningioma cells (IOMM-Lee cells) were labeled with green fluorescent protein (GFP) and implanted at the skull base of immunodeficient mice by using the postglenoid foramen injection (PGFi) technique. The animals were sacrificed at specific time points for analysis of tumor formation. Two groups of animals received adoptive immunotherapy with control peripheral blood mononuclear cells (PBMCs) or WT1-targeted PBMCs. High levels of WT1 mRNA expression were observed in many meningioma tissues and all meningioma cell lines. IOMM-Lee-GFP cells were successfully implanted using the PGFi technique, and malignant skull base meningiomas were induced in all mice. The systemically delivered WT1-targeted PBMCs infiltrated skull base meningiomas and significantly delayed tumor growth and increased survival time. We have established a reproducible mouse model of malignant skull base meningioma. WT1-targeted adoptive immunotherapy appears to be a promising approach for the treatment of difficult-to-treat meningiomas.

BAG-1 expression in human meningioma and correlation with clinical characteristics

The aim of this study is to investigate BAG-1 expression in human meningiomas and to assess its association with pathological and clinical characteristics. BAG-1 expression was analyzed in 158 specimens of meningiomas using immunohistochemical staining, and the results were graded according to the positivity ratio and the staining intensity. We examined the correlations between BAG-1 expression and the 2007 WHO pathological classification, peritumoral edema and postoperative recurrence. There were no significant differences in BAG-1 expression among meningioma subtypes within the same histopathologic grade, as well as between grades II and III. BAG-1 expression in grade I was much higher than in grade II (P < 0.05) or III (P < 0.01). BAG-1 expression was gradually decreased with increasing WHO pathologic classification (χ (2) = 141.49, P < 0.01), as well as with the increase in peritumoral edema (χ (2) = 43.93, P < 0.01) and postoperative recurrence (χ (2) = 55.13, P < 0.01). BAG-1 expression in meningioma depends upon WHO pathologic classification and is decreased in higher tumor classification. It is associated with heavier peritumoral edema and more postoperative recurrences.

Abstract B32: Preclinical testing of three immune adjuvants in vaccination therapy for invasive canine meningioma.

Abstract Malignant and atypical meningiomas are resistant to standard therapies, but therapeutic vaccines have not been tested preclinically or clinically. Pet dogs with naturally occurring meningioma are an underutilized model for aggressive human meningioma and an outstanding opportunity for assessing experimental therapeutic approaches. We treated 11 meningioma-bearing dogs with surgery and vaccine immunotherapy consisting of autologous tumor cell lysate combined with CpG or imiquimod. Interferon gamma-elaborating T cells were detected in the peripheral blood of two of cases, but vaccine-induced tumor-reactive antibody responses were found in the sera of all dogs. Systemic antibody responses were polyclonal, recognizing intracellular and cell surface antigens, and heat shock protein 60 was identified as one common antigen. Tumor-reactive antibodies bound allogeneic canine and human meningiomas, demonstrating common antigens across breed and species. Histological analysis revealed robust infiltration of antibody-secreting plasma cells into the brain around the tumor in treated compared to pre-treatment samples. Tumor-reactive antibodies were capable of inducing antibody dependent cell-mediated cytotoxicity to autologous and allogeneic tumor cells. Moreover, median survival for lysate/CpG and lysate/imiquimod vaccination was 646 days versus 222 days in historic surgery controls (p&amp;lt;0.05). Compared to CpG, a novel imidazoquinoline with TLR7/8 and inflammasome activity, compound 528, was equally potent at activating canine PBMCs. A prospective randomized two-arm trial was recently launched, using lysate—compound 528 vaccines, versus surgery controls. Mean follow-up is 139 days at the time of writing, and recruitment is ongoing. These data demonstrate the feasibility and immunologic efficacy of vaccine immunotherapy for treating a large animal model of human meningioma and warrant further development towards human trials. Citation Format: Brian M. Andersen, G Elizabeth Pluhar, Charles E. Seiler, Zhengming Xiong, Michelle R. Goulart, Matthew Gerry O'Sullivan, Matthew A. Hunt, Charles E. Schiaffo, David M. Ferguson, John R. Ohlfest. Preclinical testing of three immune adjuvants in vaccination therapy for invasive canine meningioma. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B32.

The transmembrane chemokines CXCL16 and CX3CL1 and their receptors are expressed in human meningiomas

Meningiomas are common slowly growing benign tumors, however, anaplastic meningiomas have an aggressive biological and clinical behavior associated with high rates of recurrence and unfavorable prognosis. Since the molecular mechanisms involved in progression of meningiomas are not yet fully understood and recent investigations have suggested a possible role of chemokines in tumor biology, the aim of the study was to investigate the expression of CX3CL1/CX3CR1 and CXCL16/CXCR6 on mRNA and protein level in human meningiomas. Quantitative reverse-transcription polymerase chain reaction, immunohistochemistry and double immuno-staining techniques were used for the investigations. We showed that mRNA and protein expression of the chemokine/receptor pairs CX3CL1/CX3CR1 and CXCL16/CXCR6 were detectable in human meningioma samples. Double immunostaining revealed that the chemokines/receptors were predominantly expressed in the tumor cells themselves, in infiltrating microglia cells/macrophages and endothelial cells of blood vessels. Nevertheless, not all cells of different kinds were positive for different chemokine/receptors. Of note, in comparison to more benign meningioma samples, CX3CR1 and CXCL16 were found to be expressed at lower levels in anaplastic variants. Moreover, a positive correlation between expression levels of ligands and corresponding receptors could be observed for some malignancy grades. Taken together, these results showed that chemokines and their receptors are involved in the pathogenesis of human meningiomas. Our results provide an interesting basis for further investigations that should be performed to characterize the functional roles of chemokines and their receptors in human meningiomas, and also enhance future therapeutic design.

Effect of systemic celecoxib on human meningioma after intracranial transplantation into nude mice

Meningiomas are mostly benign, but they may have a notorious tendency to recur when total resection is not possible. Systemic chemotherapeutical treatment has been largely disappointing. The treatment of meningiomas with the cyclooxygenase-2 (COX-2) inhibitor celecoxib showed inhibitory-growth effects in vitro and in vivo after subcutaneous transplantation into mouse. So far, celecoxib has never been tested in an orthotopic model of meningioma. In this work, we tested the effects of celecoxib on the growth of human benign meningiomas after transplantation into the prefrontal cortex of nude mice after confirming the inhibitory in vitro effect on these cells. Primary cell cultures were stereotactically implanted into mice and were treated with 0, 750, or 1,500ppm celecoxib for 3months. The mice were then killed and blood was analyzed for celecoxib concentration. The mice brains were histologically processed for measurement of tumor volume, COX-2 expression, proliferation index (PI), intratumoral microvessel density (iMVD), and vascular endothelial growth factor (VEGF) expression. Treatment with celecoxib had no effect on tumor volume, despite the fact that we found a dose-dependent inhibitory effect on cell cultures and there was a sufficiently high celecoxib concentration in blood plasma and brain tissue. Additionally, celecoxib had neither an effect on COX-2 and VEGF expression nor on the PI and iMVD. Our findings suggest that celecoxib may not be effective on meningioma growth in clinical settings. In general, these results may indicate that the effect of treatment on brain tumors should not only be tested in a heterotopic environment but also in the orthotopic location of these tumors.

Spatio-temporal anomalous diffusion imaging: results in controlled phantoms and in excised human meningiomas

Recently, we measured two anomalous diffusion (AD) parameters: the spatial and the temporal AD indices, called γ and α, respectively, by using spectroscopic pulse gradient field methods. We showed that γ quantifies pseudo-superdiffusion processes, while α quantifies subdiffusion processes. Here, we propose γ and α maps obtained in a controlled heterogeneous phantom, comprised of packed micro-beads in water and in excised human meningiomas. In few words, α maps represent the multi-scale spatial distribution of the disorder degree in the system, while γ maps are influenced by local internal gradients, thus highlighting the interface between compartments characterized by different magnetic susceptibility. γ maps were already obtained by means of AD stretched exponential imaging and α-type maps have been recently achieved for fixed rat brain with the aim of highlighting the fractal dimension of specific brain regions. However, to our knowledge, the maps representative of the spatial distribution of α and γ obtained on the same controlled sample and in the same excised tissue have never been compared. Moreover, we show here, for the first time, that α maps are representative of the spatial distribution of the disorder degree of the system.In a first phase, γ and α maps of controlled phantom characterized by an ordered and a disordered rearrangement of packed micro-beads of different sizes in water and by different magnetic susceptibility (Δχ) between beads and water were obtained. In a second phase, we investigated excised human meningiomas of different consistency.Results reported here, obtained at 9.4T, show that α and γ maps are characterized by a different image contrast. Indeed, unlike γ maps, α maps are insensible to (Δχ) and they are sensible to the disorder degree of the microstructural rearrangement. These observations strongly suggest that AD indices α and γ reflect some additional microstructural information which cannot be obtained using conventional diffusion methods based on Gaussian diffusion. Moreover, α and γ maps obtained in excised meningiomas seem to provide more microstructural details above those obtained with conventional DTI analysis, which could be used to improve the classification of meningiomas based on their consistency.

Immunophenotypic Identification and Characterization of Tumor Cells and Infiltrating Cell Populations in Meningiomas

Meningiomas are primary tumors of the central nervous system composed of both neoplastic and other infiltrating cells. We determined the cellular composition of 51 meningioma samples by multiparameter flow cytometric (MFC) immunophenotyping and investigated the potential relationship between mRNA and protein expression levels of neoplastic cells. For immunophenotypic, morphologic, and cytogenetic characterization of individual cell populations, a large panel of markers was used together with phagocytic/endocytic functional assays and MFC sorting. Overall, our results revealed coexistence of CD45(-) neoplastic cells and CD45(+) immune infiltrating cells in all meningiomas. Infiltrating cells included tissue macrophages, with an HLA-DR(+)CD14(+)CD45(+)CD68(+)CD16(-/+)CD33(-/+) phenotype and high phagocytic/endocytic activity, and a small proportion of cytotoxic lymphocytes (mostly T CD8(+) and natural killer cells). Tumor cells expressed multiple cell adhesion proteins, tetraspanins, HLA-I/HLA-DR molecules, complement regulatory proteins, cell surface ectoenzymes, and growth factor receptors. Noteworthy, the relationship between mRNA and protein levels was variable, depending on the proteins evaluated and the level of infiltration by immune cells. In summary, our results indicate that MFC immunophenotyping provides a reliable tool for the characterization of the patterns of protein expression of different cell populations coexisting in meningioma samples, with a more accurate measure of gene expression profiles of tumor cells at the functional/protein level than conventional mRNA microarray, independently of the degree of infiltration of the tumor by immune cells.

420PD - Systemic Temsirolimus Administration Reduces Tumor Growth in an Orthotopic Mouse Meningioma Model

ABSTRACT Disclosure C. Mawrin: Work was supported in part by Pfizer Inc. and the Deutsche Krebshilfe. D. Pachow: work was supported in part by Pfizer Inc. and the Deutsche Krebshilfe. E. Kirches: work was supported in part by Pfizer Inc. and the Deutsche Krebshilfe Meningiomas represent the most frequent intracranial tumors. While most cases correspond to WHO grade I, about 5% belong to the aggressive atypical subtype, and 1% are anaplastic meningiomas with poor clinical outcome. However, even the treatment of benign subtypes might be challenging in recurrent tumors and if complete resection is impossible. So far, no chemotherapy regime has been proven to be effective; radiotherapy is used to treat aggressive meningiomas. We have previously established that human meningiomas have activated mTORC-1 signalling, and that meningioma cells are responsive to mTORC-1 inhibitors. In the present study, we used an orthotopic mouse meningioma model established in our lab to monitore the effect of systemic temsirolimus treatment on meningioma cells grown in the subarachnoidal space. Following orthotopic injection of malignant IOMM-Lee meningioma cells, mice (n = 8) were treated daily with 20mg/kg temsirolimus intraperitoneally for nine days, beginning at day 3. Control animals (n = 8) were treated with diluent only. Tumor growth was monitored by magnetic resonance imaging (MRI). We observed that at day 9, mice treated with temsirolimus had a significantly (p

419PD - Strong Additive Effect of Everolimus and Octreotide or Pasireotide on Meningioma Cells in Vitro: A New Therapeutic Strategy for These Tumors

ABSTRACT Disclosure A. Barlier: the research prgramm was partially supported by Novartis. All other authors have declared no conflicts of interest. Meningiomas are the most frequent brain tumors after 35 years-old. When total surgical removal is not possible, radiotherapy and radiosurgery are able to control tumoral growth in some cases. But no chemotherapy has ever been demonstrated to be really efficient. Then, in cases of recurrence (particularly in WHO grade 2 and 3 meningiomas), no therapeutic exist at present, leading to fatal issue. Pi3Kinase-Akt-mTor pathway is activated in meningiomas, due to Merlin protein (encoded by NF2 gene) inactivation. SST2 somatostatin receptors are strongly expressed in meningiomas. These receptors are targeted by somatostatin agonists (octreotide and a new “pan-sst” agonist, pasireotide) which antiproliferative effect is known in other types of tumors. The aim of our study is to test in vitro effects of m-Tor inhibitor (Everolimus) and/or somatostatin agonists Octreotide or pasireotide, on human meningiomas in primary culture. By real time PCR, we found that sst2 was expressed in all meningiomas. The expression level of Merlin was highly variable between tumors and was inversely correlated with mTor pathway activation (p

Group B Streptococcus Interactions with Human Meningeal Cells and Astrocytes In Vitro

Background Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of life-threatening neonatal meningitis and survivors often suffer permanent neurological damage. How this organism interacts with the meninges and subsequently with astrocytes that constitute the underlying cortical glia limitans superficialis is not known.Methodology/Principal FindingsIn this paper, we demonstrate dose-dependent adherence of GBS over time to human meningioma cells and fetal astrocytes in vitro, which was not influenced by expression of either β-haemolysin/cytolysin (β-h/c) toxin, different capsule serotypes or by absence of capsule (p>0.05). Internalization of GBS by both cell types was, however, a slow and an infrequent event (only 0.02–0.4% of associated bacteria were internalised by 9 h). Expression of β-h/c toxin did not play a role in invasion (p>0.05), whereas capsule expression lead to a reduction (p<0.05) in the numbers of intracellular bacteria recovered. GBS strains induced cytotoxicity as demonstrated by the measurement of lactate dehydrogenase (LDH) enzyme release by 9 h and by viable staining. Increasing levels of meningioma cell death correlated with bacterial growth and the phenotype of β-h/c toxin production, i.e. from weakly, to normo- to hyper-haemolytic. However, cytotoxicity was significantly greater (p<0.05) towards astrocytes, and infection with initial MOI≥0.003 induced 70–100% LDH release. By comparing wild-type (β-h/c+) and mutant (ΔcylE β-h/c−) strains and β-h/c toxin extracts and by using the surfactant dipalmitoylphosphatidylcholine in cytotoxicity inhibition experiments, β-h/c toxin was demonstrated as principally responsible for cell death.Conclusions/SignificanceThis study has described key events in the interactions of GBS with meningeal cells and astrocytes in vitro and a major virulence role for β-h/c toxin. Understanding the mechanisms involved will help to identify potential therapies for improving patient survival and for reducing the incidence and severity of neurological sequelae.

Vascular space occupancy MRI during breathholding at 3 tesla

To evaluate the vasodilatory response of normal human brain and meningiomas under repeated breathholding challenges using vascular space occupancy (VASO) MRI at 3 Tesla (T). Five normal volunteers and five patients with meningiomas were recruited for this study. For the normal group, VASO MRI during repeated breathholds of different duration (5 to 30 s) was acquired. Patients performed a 15-s breathhold paradigm for VASO MRI. The maximum signal change and full-width at half-maximum (FWHM) were determined by curve fitting. Significant VASO signal decreases in the gray matter could be detected for a breathhold period as short as 5 s. The fractional activation volume vs. breathhold duration reached a plateau around 34.21 ± 3.39% at 15 s. In the patient group, there were significant VASO signal decreases in normal gray matters and also in small areas of three large-sized meningiomas. The 3T VASO MRI detected significant signal decreases in the gray matter, but not in the white matter, during short periods of breathholding. The fractional activation volume reached the plateau at 15-s breathhold, which is recommended for clinical application.