Meningioma Cells Research Articles

Hsa_circ_0004872 alleviates meningioma progression by sponging miR-190a-3p/PTEN signaling

BackgroundMeningioma, the most prevalent intracranial tumor, possesses a significant propensity for malignant transformation. Circular RNAs (circ-RNAs), a class of non-coding RNAs, have emerged as crucial players in tumorigenesis. This study explores the functional relevance of hsa_circ_0004872, a specific circ-RNA, in the context of meningioma.MethodsMolecular structure and stability of hsa_circ_0004872 were elucidated through PCR identification. Meningioma cell proliferation and apoptosis were assessed using the CCK-8 assay and flow cytometry, respectively. Gene and protein expression were analyzed via qRT-PCR and western blot. Molecular interactions were confirmed through dual-luciferase reporter gene and RIP assays.ResultsHsa_circ_0004872, derived from exons 2 to 4 of the host gene MAPK1, demonstrated enhanced stability compared to its host MAPK1. Clinical data described that hsa_circ_0004872 was reduced in meningioma tissues and cell lines, and negatively correlated to poor survival rate of meningioma patients. Overexpression of hsa_circ_0004872 exhibited inhibitory effects on cell proliferation and promotion of apoptosis in vitro. Subsequent investigations unveiled a direct interaction between hsa_circ_0004872 and miR-190a-3p, leading to the activation of the PI3K/AKT signaling pathway through targeting PTEN. Notably, miR-190a-3p silence accelerated the apoptosis and proliferation inhibition of meningioma cells by inactivating PTEN/PI3K/AKT signaling, while miR-190a-3p overexpression showed an opposite effect, which greatly reversed the anti-tumor effects of hsa_circ_0004872 overexpression.ConclusionIn summary, our findings highlighted the intricate role of hsa_circ_0004872 in meningioma, shedding light on the regulatory mechanisms involving circ-RNAs in tumor progression. This positions hsa_circ_0004872 as a potential key regulatory factor in meningioma with implications for future therapeutic interventions.

Single-cell transcriptome analysis upon ECM-remodeling meningioma cells.

Meningiomas are the most common tumours that primarily arise in the central nervous system, but their intratumoural heterogeneity has not yet been thoroughly studied. We aimed to investigate the transcriptome characteristics and biological properties of ECM-remodeling meningioma cells. Single-cell RNA sequencing (ScRNA-seq) data from meningioma samples were acquired and used for analyses. We conducted comprehensive bioinformatics analyses, including screening for differentially expressed genes (DEGs), Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway and Gene Ontology (GO) term enrichment analyses, Gene Set Enrichment Analysis (GSEA), protein-protein interaction (PPI) analysis, and copy number variation (CNV) analysis on single-cell sequencing data from meningiomas. Eighteen cell types, including six meningioma subtypes, were identified in the data. ECM-remodeling meningioma cells (MGCs) were mainly distributed in brain-tumour interface tissues. KEGG and GO enrichment analyses revealed that 908 DEGs were mainly related to cell adhesion, extracellular matrix organization, and ECM-receptor interaction. GSEA analysis demonstrated that homophilic cell adhesion via plasma membrane adhesion molecules was significantly enriched (NES = 2.375, P < 0.001). CNV analysis suggested that ECM-remodeling MGCs showed considerably lower average CNV scores. ECM-remodeling MGCs predominantly localized at the brain-tumour interface area and adhere stably to the basement membrane with a lower degree of malignancy. This study provides novel insights into the malignancy of meningiomas.

RACK1 Promotes Meningioma Progression by Activation of NF-κB Pathway via Preventing CSNK2B from Ubiquitination Degradation.

Higher-grade meningiomas (WHO grade II and III) are characterized by aggressive invasiveness and high postoperative recurrence rates. The prognosis remains inadequate even with adjuvant radiotherapy and currently there is no definitive pharmacological treatment strategy and target for malignant meningiomas. This study aims to unveil the mechanisms driving the malignant progression of meningiomas and to identify potential inhibitory targets, with significant clinical implications. Implementing techniques such as protein immunoprecipitation, mass spectrometry, RNA interference, and transcriptome sequencing, we investigated the malignancy mechanisms in meningioma cell lines IOMM-LEE and CH157-MN. Additionally, in vivo experiments were carried out on nude mice. We discovered a positive correlation between meningioma malignancy and the levels of the receptor for activated C kinase 1 (RACK1), which interacts with CSNK2B, the β subunit of casein kinase 2 (CK2), inhibiting its ubiquitination and subsequent degradation. This inhibition allows CK2 to activate the NF-κb pathway, which increases the transcription of CDK4 and cyclin D3, resulting in the transition of the cell cycle into the G2/M phase. The RACK1 inhibitor, harringtonolide (HA), significantly suppressed the malignant tendencies of meningioma cells. Our study suggests that RACK1 may play a role in the malignant progression of meningiomas, and therefore, targeting RACK1 could emerge as an effective strategy for reducing the malignancy of these tumors.

A gain of function mutation in AKT1 increases hexokinase 2 and diminishes oxidative stress in meningioma

Increasing evidence suggests the oncogenic role of missense mutation (AKT1-E17K) of AKT1 gene in meningiomas. Upon investigating the connection between the pro-tumorigenic role of AKT1-E17K and cellular metabolic adaptations, elevated levels of glycolytic enzyme hexokinase 2 (HK2) was observed in meningioma patients with AKT1-E17K compared to patients harboring wild-type AKT1. In vitro experiments also suggested higher HK2 levels and its activity in AKT1-E17K cells. Treatment with the conventional drug of choice AZD5363 (a pan AKT inhibitor) enhanced cell death and diminished HK2 levels in AKT1 mutants. Given the role of AKT phosphorylation in eliciting inflammatory responses, we observed increased levels of inflammatory mediators (IL-1β, IL6, IL8, and TLR4) in AKT1-E17K cells compared to AKT1-WT cells. Treatment with AKT or HK2 inhibitors dampened the heightened levels of inflammatory markers in AKT1-E17K cells. As AKT and HK2 regulates redox homeostasis, diminished ROS generation concomitant with increased levels of NF-E2– related factor 2 (Nrf2) and superoxide dismutase 1 (SOD1) were observed in AKT1-E17K cells. Increased sensitivity of AKT1-E17K cells to AZD5363 in the presence of HK2 inhibitor Lonidamine was reversed upon treatment with ROS inhibitor NAC. By affecting metabolism, inflammation, and redox homeostasis AKT1-E17K confers a survival advantage in meningioma cells. Our findings suggest that targeting AKT-HK2 cross-talk to induce ROS-dependent cell death could be exploited as novel therapeutic approach in meningiomas.

Altered O-linked glycosylation in benign and malignant meningiomas.

Changes in protein glycosylation have been reported in various diseases, including cancer; however, the consequences of altered glycosylation in meningiomas remains undefined. We established two benign meningioma cell lines-SUT-MG12 and SUT-MG14, WHO grade I-and demonstrated the glycan and glycosyltransferase profiles of the mucin-type O-linked glycosylation in the primary benign meningioma cells compared with two malignant meningioma cell lines-HKBMM and IOMM-Lee, WHO grade III. Changes in O-linked glycosylation profiles in malignant meningiomas were proposed. Primary culture technique, morphological analysis, and immunocytochemistry were used to establish and characterize two benign meningioma cell lines. The glycan profiles of the primary benign and malignant meningiomas cell lines were then analyzed using lectin cytochemistry. The gene expression of O-linked glycosyltransferases, mucins, sialyltransferases, and fucosyltransferases were analyzed in benign and malignant meningioma using the GEO database (GEO series GSE16581) and quantitative-PCR (qPCR). Lectin cytochemistry revealed that the terminal galactose (Gal) and N-acetyl galactosamine (GalNAc) were highly expressed in primary benign meningioma cells (WHO grade I) compared to malignant meningioma cell lines (WHO grade III). The expression profile of mucin types O-glycosyltransferases in meningiomas were observed through the GEO database and gene expression experiment in meningioma cell lines. In the GEO database, C1GALT1-specific chaperone (COSMC) and mucin 1 (MUC1) were significantly increased in malignant meningiomas (Grade II and III) compared with benign meningiomas (Grade I). Meanwhile, in the cell lines, Core 2 β1,6-N-acetylglucosaminyltransferase-2 (C2GNT2) was highly expressed in malignant meningiomas. We then investigated the complex mucin-type O-glycans structures by determination of sialyltransferases and fucosyltransferases. We found ST3 β-galactoside α-2,3-sialyltransferase 4 (ST3GAL4) was significantly decreased in the GEO database, while ST3GAL1, ST3GAL3, α1,3 fucosyltransferases 1 and 8 (FUT1 and FUT8) were highly expressed in malignant meningioma cell lines-(HKBMM)-compared to primary benign meningioma cells-(SUT-MG12 and SUT-MG14). Our findings are the first to demonstrate the potential glycosylation changes in the O-linked glycans of malignant meningiomas compared with benign meningiomas, which may play an essential role in the progression, tumorigenesis, and malignancy of meningiomas.

Establishment of tumor microenvironment-preserving organoid model from patients with intracranial meningioma

BackgroundAlthough meningioma is the most common primary brain tumor, treatments rely on surgery and radiotherapy, and recurrent meningiomas have no standard therapeutic options due to a lack of clinically relevant research models. Current meningioma cell lines or organoids cannot reflect biological features of patient tumors since they undergo transformation along culture and consist of only tumor cells without microenvironment. We aim to establish patient-derived meningioma organoids (MNOs) preserving diverse cell types representative of the tumor microenvironment.MethodsThe biological features of MNOs were evaluated using WST, LDH, and collagen-based 3D invasion assays. Cellular identities in MNOs were confirmed by immunohistochemistry (IHC). Genetic alteration profiles of MNOs and their corresponding parental tumors were obtained by whole-exome sequencing.ResultsMNOs were established from four patients with meningioma (two grade 1 and two grade 2) at a 100% succession rate. Exclusion of enzymatic dissociation-reaggregation steps endowed MNOs with original histology and tumor microenvironment. In addition, we used a liquid media culture system instead of embedding samples into Matrigel, resulting in an easy-to-handle, cost-efficient, and time-saving system. MNOs maintained their functionality and morphology after long-term culture (> 9 wk) and repeated cryopreserving-recovery cycles. The similarities between MNOs and their corresponding parental tumors were confirmed by both IHC and whole-exome sequencing. As a representative application, we utilized MNOs in drug screening, and mifepristone, an antagonist of progesterone receptor, showed prominent antitumor efficacy with respect to viability, invasiveness, and protein expression.ConclusionTaken together, our MNO model overcame limitations of previous meningioma models and showed superior resemblance to parental tumors. Thus, our model could facilitate translational research identifying and selecting drugs for meningioma in the era of precision medicine.

Clinicopathological features of intravascular large B-cell lymphoma and collision tumors of five cases

Objective: To investigate the clinicopathological characteristics, diagnosis and differential diagnosis of intravascular large B-cell lymphoma (IVLBCL) and its collision tumors. Methods: Five cases of IVLBCL were collected, including 2 cases of collision tumors, and 1 case complicated with liver cirrhosis. The morphology and immunophenotype were analyzed. The related literature was reviewed. Results: There were 2 females and 3 males, aged from 53 to 73 years, with a median age of 65 years. The tumors were located in the lower extremities, right cerebellar hemisphere, left kidney, bilateral nasal cavity, and liver, respectively. Cases 2 and 3 were incidentally found in meningioma and renal cell carcinoma tissues, respectively. Case 5 had a background of liver cirrhosis. Morphologically, atypical large lymphoid cells were located in small blood vessels and capillary lumen, with little cytoplasm, hyperchromasia, prominent nucleoli, and obvious mitotic figures. Immunohistochemically, the IVLBCL tumor cells expressed CD20 and PAX5; 2 cases were CD5 positive. One of the 5 cases was GCB phenotype, and 4 cases were non-GCB phenotype. All cases expressed C-MYC (positive rate was 10%-40%). PD-L1 was positive in 4 cases (positive rate was 60%-90%). Ki-67 proliferation index was 70%-90%. CKpan, CD3, TDT, and CD34 were negative. In case 2, meningioma cells were positive for PR, EMA, and vimentin, but negative for CKpan and PD-L1. In case 3, renal carcinoma cells were positive for CKpan, PAX8, EMA, vimentin, CAⅨ and CD10, while PD-L1 was negative. No EBER expression (by in situ hybridization) or C-MYC gene translocation (FISH, break-apart probe) was detected in any of the 5 cases. Three patients were followed up, and all died within 1-13 months. Conclusions: IVLBCL is a highly aggressive lymphoma, with occult clinical manifestations and poor prognosis. Collision tumors of IVLBCL are extremely rare. A better understanding of IVLBCL would help pathologists avoid misdiagnoses.

Parasagittal Meningioma in a Middle-aged Female Harbouring Metastatic Ductal Carcinoma: A Rare Case of Incidentally Detected Tumour-to-tumour Metastasis

Metastasis of a tumour particularly coming from breast into an intracranial meningioma is a rare phenomenon. Several factors related to tumour microenvironment have been suggested in the pathophysiology of these lesions, particularly the rich vascular network of meningiomas, expression of common hormonal receptors like Oestrogen Receptor (ER) and Progesterone Receptor (PR), local immunosuppression, and presence of cell adhesion molecules. Here, we present a clinicoradiologically unsuspecting case of intracranial, parasagittal meningioma who was operated for relief of symptoms of mass effect and was incidentally detected with tumour metastasis within the meningioma. A 50-year-old female presented with seizures, headache and visual disturbances since last one month. Radiology revealed a parasagittal mass which was likely to be meningioma. The patient was operated. On histopathology, a low-grade meningioma was seen with areas of metastatic adenocarcinoma. The metastatic foci were surrounded by fibroblastic meningioma cells. On Immunohistochemistry (IHC), the metastatic tumour cells were strongly positive for PR and Cytokeratin 7 (CK7) and a diagnosis of fibroblastic meningioma with intratumoural metastasis of ductal carcinoma was rendered. The patient was given radiotherapy for brain tumour and also started on chemotherapy for breast carcinoma with brain metastasis. Since the entity of “Tumour-to-tumour Metastasis (TTM)” is uncommonly thought of and its detection is not easy, it is important that both clinicians and pathologists should adequately examine tissue samples of excised meningioma, as detecting the presence of any metastatic foci within the main mass will alter the prognosis and treatment plan considerably.

The migratory and invasive behaviour of malignant meningioma cells depends on glucose concentration and glycation

The migratory and invasive behaviour of malignant meningioma cells depends on glucose concentration and glycation

Preclinical evaluation of the third-generation, bi-steric mechanistic target of rapamycin complex 1-selective inhibitor RMC-6272 in NF2-deficient models.

NF2-associated meningiomas are progressive, highly morbid, and nonresponsive to chemotherapies, highlighting the need for improved treatments. We have established aberrant activation of the mechanistic target of rapamycin (mTOR) signaling in NF2-deficient tumors, leading to clinical trials with first- and second-generation mTOR inhibitors. However, results have been mixed, showing stabilized tumor growth without shrinkage offset by adverse side effects. To address these limitations, here we explored the potential of third-generation, bi-steric mTOR complex 1 (mTORC1) inhibitors using the preclinical tool compound RMC-6272. Employing human NF2-deficient meningioma lines, we compared mTOR inhibitors rapamycin (first-generation), INK128 (second-generation), and RMC-6272 (third-generation) using in vitro dose-response testing, cell-cycle analysis, and immunoblotting. Furthermore, the efficacy of RMC-6272 was assessed in NF2-null 3D-spheroid meningioma models, and its in vivo potential was evaluated in 2 orthotopic meningioma mouse models. Treatment of meningioma cells revealed that, unlike rapamycin, RMC-6272 demonstrated superior growth inhibitory effects, cell-cycle arrest, and complete inhibition of phosphorylated 4E-BP1 (mTORC1 readout). Moreover, RMC-6272 had a longer retention time than INK128 and inhibited the expression of several eIF4E-sensitive targets on the protein level. RMC-6272 treatment of NF2 spheroids showed significant shrinkage in size as well as reduced proliferation. Furthermore, in vivo studies in mice revealed effective blockage of meningioma growth by RMC-6272, compared with vehicle controls. Our study in preclinical models of NF2 supports possible future clinical evaluation of third-generation, investigational mTORC1 inhibitors, such as RMC-5552, as a potential treatment strategy for NF2.

10008-CBMS-1 THE NOVEL MDM4 INHIBITOR CEP-1347 ACTIVATES THE P53 PATHWAY AND BLOCKS MALIGNANT MENINGIOMA GROWTH IN VITRO AND IN VIVO

Abstract A significant proportion of meningiomas are clinically aggressive, but there is currently no effective chemotherapy for meningiomas. An increasing number of studies have been conducted to develop targeted therapies, yet none have focused on the p53 pathway as a potential target. In this study, we aimed to determine the in vitro and in vivo effects of CEP-1347, a small-molecule inhibitor of MDM4 with known safety in humans. The effects of CEP-1347 and MDM4 knockdown on the p53 pathway in human meningioma cell lines with and without p53 mutation were examined by RT-PCR and Western blot analyses. The growth inhibitory effects of CEP-1347 was examined in vitro and in a mouse xenograft model of meningioma. In vitro, CEP-1347 at clinically relevant concentrations inhibited MDM4 expression, activated the p53 pathway in malignant meningioma cells with wild-type p53, and exhibited preferential growth inhibitory effects on cells expressing wild-type p53, which was mostly mimicked by MDM4 knockdown. CEP-1347 effectively inhibited the growth of malignant meningioma xenografts at a dose that was far lower than the maximum dose that could be safely given to humans. Our findings suggest targeting the p53 pathway with CEP-1347 represents a novel and viable approach to treating aggressive meningiomas.

Translocator protein (TSPO) expression in neoplastic cells and tumor-associated macrophages in meningiomas.

Meningiomas are the most common primary intracranial tumors and show extensive infiltration of macrophages. The mitochondrial membrane protein translocator protein (TSPO) has been used as an in vivo marker of microglia and macrophage activation to visualize neuroinflammation. However, it is unknown which cell types express TSPO in meningiomas. Immunohistochemistry of 38 WHO grade 1-3 meningiomas was subjected to segmentation and deep learning classification of TSPO expression to either Iba1-positive tumor-associated macrophages (TAMs) or all other (mainly neoplastic) cells. A possible association between clinical data and TSPO expression intensities was also investigated. TAMs accounted for 15.9%-26% of all cells in the meningioma tissue. Mean fluorescence intensity of TSPO was significantly higher in TAMs (p < 0.0001), but the mass of neoplastic cells in the tumors exceeded that of TAMs. Thus, the summed fluorescence intensity of TSPO in meningioma cells was 64.1% higher than in TAMs (p = 0.0003). We observed no correlation between TSPO expression intensity and WHO grade. These results indicate that both macrophage-lineage and neoplastic cells in meningiomas express TSPO and that the SPECT-TSPO signal in meningiomas mainly reflects the latter; TSPO is expressed equally in parenchymal activated and resting macrophage/microglia lineage cells.

EXTH-57. THE IGF-2 SIGNALING PATHWAY IS A PROMISING MENINGIOMA TREATMENT TARGET

Abstract Meningioma is the most common primary central nervous system tumor often causing serious complications while there is no effective medical treatment. We developed a tumor-derived primary culture model featuring tumor cells with retained PDG2S lineage marker as well as non-arachnoid cells mimicking the tumor cell microenvironment. We used this model to test the relevance of miRNA differentially expressed in meningioma tumor samples identified by small RNA sequencing. We found that in all meningiomas studied, there was activation of the IGF2/miR-483 locus with high expression of both miR-483-5p and IGF2. Inhibition of miR-483-5p reduced the growth of cultured meningioma cells, whereas a miR-483 mimic increased cell proliferation. Anti-IGF2 neutralizing antibodies reduced meningioma cell proliferation. Small molecule tyrosine kinase inhibitor blockade of the IGF2 receptor (IGF1R) resulted in rapid loss of viability of cultured meningioma tumor-derived cells. Autocrine IGF2 feed-back appears to be obligatory for meningioma tumor cell survival and growth. Inhibition of this circuit with IGF1R small molecule tyrosine kinase inhibitors or receptor-binding antibodies as well as anti-IGF2 neutralizing antibodies may have therapeutic potential for meningioma.

EXTH-71. AUTOMATED AND MULTIPLEXED COMBINATORIAL DRUG SCREENING OF FDA-APPROVED DRUGS IDENTIFIES POTENTIAL SYNERGISTIC DRUG PARTNERS FOR THE TREATMENT OF AGGRESSIVE MENINGIOMAS

Abstract The goal of combinatorial therapy is to improve the effectiveness of treatment by targeting multiple aspects of cancer cells or by overcoming resistance to single drugs. In search of effective synergistic drug combinations for the treatment of aggressive meningiomas, we performed an automated and multiplexed combinatorial drug screening of 166 FDA-approved anticancer drugs in three grade 3 meningioma cell lines. Three anaplastic meningioma cell lines (NCH93, IOMM-Lee, and KT21-MG1) were stably transduced with blue, green, and red fluorescence proteins. The cell lines were multiplexed into 384-well plates and treated in 5x5 dose-response matrices (1 to 1000 nmol/L) for 48 hours by the automated liquid handler Hamilton MicroLAB STAR®. The drug library consisted of 166 FDA-approved anticancer drugs. To demultiplex cell viability from a single well, fluorescence as a surrogate marker for viability was measured before adding an ATP-based end-point viability assay, which served as an independent combined result of all cell lines (combined group). Synergism was calculated by the ZIP Synergy model and was defined as a ZIP score over 10. This drug screening effort generated 13695 unique drug-drug combinations per cell line. Most synergistic combinations were observed in the combined group (n = 188, 1.37%), followed by IOMM-Lee (n = 157, 1.14%), and KT21-MG1 (n = 122, 0.88%). The lowest number of synergistic combinations was observed in NCH93 (n = 75, 0.54%). Interestingly, 86 combinations were uniquely found in IOMM-Lee, 54 in KT21-MG1, and 20 in NCH93, indicating specific tumor vulnerabilities. 19 drug combinations were observed in all cell lines. Of those, the drugs Temsirolimus, Gemcitabine, and Romidepsin were highly enriched. For example, mTORi Temsirolimus concordantly showed strong synergism with the androgen receptor antagonist Darolutamide in all cell lines (ZIP score: 27.75, P&amp;lt; .0001). This comprehensive combinatorial drug screening identified synergistic drug-drug partners for the treatment of aggressive meningiomas. Validation studies in patient-derived meningioma organoids are ongoing.

MODL-04. ESTABLISHMENT OF TUMOR MICROENVIRONMENT-PRESERVING ORGANOID MODEL FROM PATIENTS WITH INTRACRANIAL MENINGIOMA

Abstract Although meningioma is the most common primary brain tumor, treatments depend only on the surgery and radiotherapy, and recurrent meningiomas have no standard therapeutic options due to a lack of clinically relevant research models. Current meningioma cell lines or organoids cannot reflect biological features of patients’ tumors since they undergo transformation along culture and consist of only tumor cells without microenvironment. Here, we firstly established patient-derived meningioma organoids (MNOs) preserving diverse cell types of tumor microenvironment, including endothelial cells and macrophage/microglia cells. Exclusion of the enzymatic dissociation-reaggregation steps endowed MNOs with original histology and tumor microenvironment. In addition, we used liquid media culture system instead of embedding into Matrigel, thus easy-to-handle, cost-efficient, and time-saving. MNOs maintained their functionality and morphology after long-term culture ( &amp;gt; 9 wk) and repeated cryopreserving-recovery cycles. The similarity between MNOs and their corresponding parental tumors were confirmed by both immunohistochemistry and whole-exome sequencing. As a representative application, we utilized MNOs in drug screening, and mifepristone, an antagonist of progesterone receptor, showed prominent antitumor efficacy in respect to viability, invasiveness, and protein expression. Taken together, our MNO model overcame limitations of previous meningioma models and showed superiority in terms of resemblance with parental tumors. Thus, we expect that our model can facilitate translational research of identifying and selecting drugs for meningioma in the era of precision medicine.

SURG-01. DIFFERENTIATION OF GLIOBLASTOMA AND MALIGNANT MENINGIOMA FROM NORMAL BRAIN BY TISSUE STIFFNESS UTILIZING MICROSURGICAL FORCEPS EQUIPPED WITH HAPTICS TECHNOLOGY

Abstract Stiffness of human cancers strongly correlate with their pathology, and it is reported that stiffness can be used as a biomarker. Furthermore, comprehensive analysis has suggested the usefulness of cancer stiffness in diagnosis and malignancy prediction and its association with molecular expression, as well as its potential for predicting and diagnosing postoperative complications. Neurosurgeons perform tumor resection relying on the sensations that they feel with their own fingertips (tactile sensation), but it takes years of surgical experience to accurately distinguish brain tumor from the surrounding normal brain tissue. Haptics is a new technology regarding touching sensation. Especially, our technology, real haptics, can communicate, record, and reproduce the real sensation. It is also possible to measure and analyze the physical property such as stiffness of the touching object from the obtained haptic data. We developed a surgical forceps equipped with haptics technology to distinguish brain tumor tissue from surrounding normal brain tissue. three glioblastoma cell lines (SF126, U87, U251) and a malignant meningioma cell line (IOMM-Lee) were each transplanted intracranially into 5 nude mice. Tumor size was periodically monitored and mice were euthanized at appropriate time points. The stiffness of the tumor and normal brain tissue was measured using a master-slave integrated surgical forceps prototype. The results statistically showed that all four types of brain tumor tissues were stiffer than normal brain tissues. (p = 0.001) In addition, malignant meningioma was statistically stiffer than glioblastomas. (p = 0.025) This result is consistent with actual surgical sensations. We have shown that our surgical forceps has the ability to distinguish pathology of brain tumors as well as to distinguish brain tumor from normal brain tissue. The forceps is also helpful for the neurosurgeons to sense minute change in tissue stiffness.

RBIO-11. BASAL BCL-2-INTERACTING MEDIATOR OF CELL DEATH (BIM) RESPONSIVENESS CORRELATES WITH RADIOSENSITIVITY IN MENINGIOMA

Abstract INTRODUCTION Radiotherapy remains the primary adjunctive treatment for recurrent or progressive meningioma. Nevertheless, varied clinical response to radiotherapy in meningioma remains a challenge, particularly in higher grade tumors. Currently there is a paucity of predictors of radio-sensitivity. Bim peptide is an intrinsic mediator of apoptosis, and Bim-responsiveness has been postulated as a metric of general sensitivity to apoptotic stress. Herein we investigated its utility as a metric of radio-sensitivity in meningioma. METHODS In an in vitro model of meningioma, a number of immortalized human and murine meningioma cell lines and patient-derived primary cultures (WHO grades 1 + 2), were exposed to ionizing radiation at range of doses (0, 2, 4, 8, 16Gy); cells were counted (Celigo, Nexelcom) to assess for growth. Separately, cultures were irradiated at 4Gy and apoptosis was analyzed 24H later using Annexin/PI staining by flow cytometry (Attune NxT). Lastly, untreated cultures were exposed to Bim peptide as a range of doses (0.01uM-10uM); induction of apoptosis was assessed via cytochrome C staining by flow cytometry. RESULTS We were able to recapitulate a wide range of radio-sensitivities both by growth metrics and radiation-induced apoptosis. Immortalized lines showed more radiation-induced growth inhibition relative to primary cultures (p = 0.03). Activation of apoptosis in response to Bim exposure demonstrated a similarly wide range of basal apoptotic sensitivities, akin to that seen for radio-sensitivity. In fact, there was a significant correlation (Pearson, p &amp;lt; 0.01) between Bim-responsiveness and levels of radiation-induced apoptosis. CONCLUSIONS We identify basal state Bim-responsiveness as a potential predictor of radio-sensitivity in meningioma. Further work in this vein may shed light on mechanisms of radio-resistance in meningioma, particularly with respect to the interaction of Bim with the anti-apoptotic members of the Bcl-2 family.

TMET-21. PROTON MAGNETIC RESONANCE SPECTROSCOPY (1H MRS) FOR THE DIAGNOSIS OF AGGRESSIVE MENINGIOMAS WITH RECURRENCE POTENTIAL

Abstract In our previous study, we have observed elevated steady state levels of both alanine and glutamine in surgically resected tissue specimens from atypical meningioma (grade-II) patients compared to the benign (grade-I) meningioma patients. We have shown that meningioma cells utilize glutamine for the biosynthesis of alanine and other amino acids which may help in the cellular proliferation. While the role of elevated alanine in meningiomas is not well understood, this metabolite may serve as a metabolic marker for the diagnosis of aggressive meningiomas which may recur in the future. Here, we present a case of a large meningioma (7 cm x 4 cm x 8 cm) in a male patient (age: 68 years) who was diagnosed with an anterior cranial fossa, dural based extra-axial enhancing mass with the sinonasal extension compatible with a meningioma. The patient underwent multiple surgeries for the resection of the original tumor mass. Tumor tissue was collected from 2 regions: Nasal cavity and deeper tumor. Surgical pathology classified the tumor as a grade-I meningioma with MIB-1 index of ~10%. However, 1H MRS analysis of the tumor specimen showed elevated levels of alanine (Nasal cavity = 9.57 mM/g, tissue; Deep tumor = 5.50 mM/g, tissue), which are greater than the alanine levels reported for grade-II meningiomas (4.23 ± 1.92 mM). The elevated levels of alanine detected by 1H MRS suggested aggressive behavior of the tumor. After about 11 months, the repeat MRI examination showed tumor recurrence, and the patient underwent surgery again for the resection of the recurrent tumor. Surgical pathology of the recurrent tumor classified the tumor as a grade-I meningioma with increased proliferation rate (MIB-1 index of 10-12%). In conclusion, 1H MRS has potential to predict aggressive behavior of meningiomas and alanine can be used as a molecular marker for the differential diagnosis of meningiomas.

ANGI-11. MOLECULAR MECHANISM OF TARGETING EPITHELIAL MEMBRANE PROTEIN-2 IN MALIGNANT MENINGIOMAS

Abstract BACKGROUND Meningiomas comprise approximately one-third of all primary central nervous system neoplasms. While many meningiomas remain benign, as many as 35% of meningiomas are graded as atypical or anaplastic/malignant with a 5-y survival rate as low as 35%. Targeting the tetraspan protein epithelial membrane protein-2 (EMP2)-HIF1α pathway through EMP2 knockdown may inhibit tumor growth, invasion, and neoangiogenesis in malignant meningioma. METHODS In collaboration with the UCLA Brain Tumor SPORE, we gathered a panel of malignant meningiomas (IOMM-LEE, CH157). To determine the function of EMP2, we created EMP2 vector control and knockdown models in both cell lines and analyzed the cells by RNA sequencing, transcriptomic functional analysis, and migration assay. RESULTS Gene functional analysis enriched for biological processes showed that knockdown of EMP2 inhibited multiple malignant pathways in these meningioma cells including the response to hypoxia, cell proliferation, invasion, and stem cell maintenance. Further analyses of EMP2 expression with other differentially expressed genes of interest revealed that VEGFA expression significantly decreased when EMP2 is knocked down (p&amp;lt; 0.001). Moreover, cellular migration and invasion regulated by EMP2 were tested in control and EMP2 knockdown malignant cells using a scratch assay, where knockdown of EMP2 reduced the rate of cell invasion by 50% (p = 0.0003). Additionally, anti-EMP2 mAb treatment in the control malignant cell line significantly reduced EMP2-mediated signal transduction (p = 0.0031). CONCLUSIONS Our study is the first to demonstrate the modulation of EMP2 and its implications in malignant meningioma pathogenesis, VEGFA-HIF1α pathway, and stem cell regulation. Targeting EMP2 may result in therapeutic benefits for malignant meningioma.

The role of m6A RNA methylation regulator in meningioma.

Meningiomas are common intracranial tumors, and the effect of surgical resection is often unsatisfactory. N6-Methyladenosine (m6A)-related regulator expression levels are related to cancer occurrence and development. This study aimed to investigate the roles of m6A RNA methylation regulators in meningiomas, as these are currently unclear. Two m6A methylation-regulated genes (METTL3 and IGF2BP2) were identified as survival-associated linear models for RiskScore through bioinformatics analysis. Univariate and multivariate Cox regression analyses showed that the overall survival of patients with meningioma in the high-risk group was substantially shorter than that in the low-risk group. Weighted gene co-expression network analysis constructed a co-expression network based on the m6A methylation model (RiskScore). Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes analyses identified the biological processes of hub module gene behavior, and Cytoscape constructed an m6A methylation-related gene regulatory network. In vitro experiments verified that the mRNA and protein expression levels of METTL3 and IGF2BP2 were lower in meningioma cells than in normal meningioma cells. Therefore, central regulators of m6A methylation (METTL3 and IGF2BP2) could potentially serve as novel therapeutic targets in meningioma. Subsequently, a novel methylation signature (RiskScore) was developed for prognostic prediction in patients with meningioma.