Malignant Meningioma Cell Research Articles

EXTH-54. PHOTODYNAMIC ONCOLYTIC VIROTHERAPY INCORPORATING GENETICALLY ENGINEERED PHOTOSENSITIZER KILLERRED FOR THE TREATMENT OF CENTRAL NERVOUS SYSTEM MALIGNANCIES

Abstract BACKGROUND Photodynamic therapy (PDT) is a targeted cancer therapy utilizing tumor-specific accumulation of photosensitizers and generation of reactive oxygen species (ROS) upon receiving specific light. The deadly CNS malignancies, high-grade gliomas and malignant meningioma, represent excellent candidates for this therapeutic method due to accessibility to light irradiation at the time of surgery. On the other hand, oncolytic virotherapy using a genetically engineered oncolytic herpes simplex virus (oHSV), has been intensively investigated as a multi-mechanistic therapy against these tumors. One of the advantages of oHSV is its ability to incorporate therapeutic transgenes. Our study aims to address our hypothesis that incorporating KillerRed, the first fully genetically encoded photosensitizing fluorescent protein, into oHSV will establish photodynamic oncolytic virotherapy that enhances tumoricidal efficacy as a novel treatment approach to CNS neoplasms. METHOD The optical properties of the intracellular KillerRed protein expressed in cells were determined by scanning by a multi-mode microplate reader to determine the optimal irradiation wavelength. In vitro efficacy of KillerRed-mediated PDT was tested using human glioblastoma and malignant meningioma cell lines. oHSV G47delta expressing KillerRed was constructed by a bacterial artificial chromosome-based method. KillerRed-transduced cells were confirmed to express red fluorescence, followed by irradiation by an amber color LED. Cell death and viability were assessed by DAPI staining and MTS assay, respectively. ROS generation post light treatment was assessed by DCF-DA cellular ROS assay. RESULTS KillerRed had an excitation peak at 580-585nm in transduced cells. Light irradiation by an amber LED after infection with G47delta-KillerRed induced increased cell growth inhibition and death compared with virus infection without light or light alone. Increased ROS production was observed following KillerRed PDT. CONCLUSION G47delta-KillerRed enables a combination of oncolytic virus therapy and PDT to augment tumor killing. This approach is being tested in in vivo mouse models using potent focused laser irradiation.

Efficacy of decitabine in malignant meningioma cells: relation to promoter demethylation of distinct tumor suppressor and oncogenes and independence from TERT.

Chemotherapeutic options for meningiomas refractory to surgery or irradiation are largely unknown. Human telomerase reverse transcriptase (hTERT) promoter methylation with subsequent TERT expression and telomerase activity, key features in oncogenesis, are found in most high-grade meningiomas. Therefore, the authors investigated the impact of the demethylating agent decitabine (5-aza-2'-deoxycytidine) on survival and DNA methylation in meningioma cells. hTERT promoter methylation, telomerase activity, TERT expression, and cell viability and proliferation were investigated prior to and after incubation with decitabine in two benign (HBL-52 and Ben-Men 1) and one malignant (IOMM-Lee) meningioma cell line. The global effects of decitabine on DNA methylation were additionally explored with DNA methylation profiling. High levels of TERT expression, telomerase activity, and hTERT promoter methylation were found in IOMM-Lee and Ben-Men 1 but not in HBL-52 cells. Decitabine induced a dose-dependent significant decrease of proliferation and viability after incubation with doses from 1 to 10 μM in IOMM-Lee but not in HBL-52 or Ben-Men 1 cells. However, effects in IOMM-Lee cells were not related to TERT expression, telomerase activity, or hTERT promoter methylation. Genome-wide methylation analyses revealed distinct demethylation of 14 DNA regions after drug administration in the decitabine-sensitive IOMM-Lee but not in the decitabine-resistant HBL-52 cells. Differentially methylated regions covered promoter regions of 11 genes, including several oncogenes and tumor suppressor genes that to the authors' knowledge have not yet been described in meningiomas. Decitabine decreases proliferation and viability in high-grade but not in benign meningioma cell lines. The effects of decitabine are TERT independent but related to DNA methylation changes of promoters of distinct tumor suppressor genes and oncogenes.

Curcumin Inhibits HGF-Induced EMT by Regulating c-MET-Dependent PI3K/Akt/mTOR Signaling Pathways in Meningioma.

Meningiomas, which are the most common primary intracranial tumors, have highly aggressive cells in malignant cases. Due to its extensive antitumor effects, curcumin is widely used in experimental and clinical studies. However, the role of curcumin during the epithelial-mesenchymal transition (EMT) in meningioma has not been established. We found that curcumin blocks hepatocyte growth factor- (HGF-) induced proliferation, migration, invasion, and EMT of human malignant meningioma cells by regulating the PI3K/Akt/mTOR signaling pathway. In addition, treatment of human malignant meningioma cells with the tyrosine protein kinase (c-MET) inhibitor (SU11274) or the phosphoinositide 3-kinase (PI3K) inhibitor (LY294002) suppressed HGF-induced migration and EMT. Furthermore, we found that curcumin inhibited tumor growth and HGF-induced EMT in mice subjected to subcutaneous xenotransplantation. These findings indicate that HGF regulates EMT in human malignant meningioma cells through c-MET/PI3K/Akt/mTOR modulation. In conclusion, curcumin inhibits HGF-induced EMT by targeting c-MET and subsequently blocking the PI3K/Akt/mTOR pathway.

Newly established patient-derived organoid model of intracranial meningioma.

Recent comprehensive studies have revealed several molecular alterations that are frequently found in meningiomas. However, effective treatment reagents targeting specific molecular alterations have not yet been identified because of the limited number of representative research models of meningiomas. We performed organoid cultures using meningioma cells and meningioma tumor tissues. Using immunohistochemistry and molecular analyses consisting of whole-exome sequencing, RNA-seq, and DNA methylation analyses, we compared the histological findings and molecular profiling of organoid models with those of parental tumors. Further, using these organoid models together with a public database of meningiomas, we explored molecular alterations, which are a potent treatment target for meningioma. We established 18 organoid models comprising of two malignant meningioma cells (HKBMM and IOMM-Lee), 10 benign meningiomas, four malignant meningiomas, and two solitary fibrous tumors (SFTs). The organoids exhibited consistent histological features and molecular profiles with those of the parental tumors. Using a public database, we identified that upregulated forkhead box M1 (FOXM1) was correlated with increased tumor proliferation. Overexpression of FOXM1 in benign meningioma organoids increased organoid proliferation; depletion of FOXM1 in malignant organoids decreased proliferation. Additionally, thiostrepton, a FOXM1 inhibitor combined with radiation therapy, significantly inhibited the proliferation of malignant meningioma organoid models. An organoid model for meningioma enabled us to elucidate the tumor biology of meningioma along with potent treatment targets for meningioma.

Anticancer activity of bergenin against cervical cancer cells involves apoptosis, cell cycle arrest, inhibition of cell migration and the STAT3 signalling pathway.

[This retracts the article DOI: 10.3892/etm.2019.7380.].

Crispr/Cas-based modeling of NF2 loss in meningioma cells

BackgroundAlterations of the neurofibromatosis type 2 gene (NF2) occur in more than fifty percent of sporadic meningiomas. Meningiomas develop frequently in the setting of the hereditary tumor syndrome NF2. Investigation of potential drug-based treatment options has been limited by the lack of appropriate in vitro and in vivo models. New methodsUsing Crispr/Cas gene editing, of the malignant meningioma cell line IOMM-Lee, we generated a pair of cell clones characterized by either stable knockout of NF2 and loss of the protein product merlin or retained merlin protein (transfected control without gRNA). ResultsIOMM-Lee cells lacking NF2 showed reduced apoptosis and formed bigger colonies compared to control IOMM-Lee cells. Treatment of non-transfected IOMM-Lee cells with the focal adhesion kinase (FAK) inhibitor GSK2256098 resulted in reduced colony sizes. Orthotopic mouse xenografts showed the formation of convexity tumors typical for meningiomas with NF2-depleted and control cells. Comparison with existing methodsNo orthotopic meningioma models with genetically-engineered cell pairs are available so far. ConclusionOur model based on Crispr/Cas-based gene editing provides paired meningioma cells suitable to study functional consequences and therapeutic accessibility of NF2/merlin loss.

Gemcitabine radiosensitization primes irradiated malignant meningioma cells for senolytic elimination by navitoclax.

BackgroundMalignant meningioma is an aggressive tumor that requires adjuvant radiotherapy after surgery, yet there has been no standard systemic therapy established so far. We recently reported that malignant meningioma cells are highly sensitive to gemcitabine; however, it remains unknown whether or how gemcitabine interacts with ionizing radiation (IR) in malignant meningioma cells.MethodsWe examined the radiosensitization effects of gemcitabine using malignant meningioma cell lines and xenografts and explored the underlying mechanisms.ResultsGemcitabine sensitized malignant meningioma cells to IR through the induction of senescence both in vitro and in vivo. Gemcitabine augmented the intracellular production of reactive oxygen species (ROS) by IR, which, together with cell growth suppression/senescence induced by this combination, was inhibited by N-acetyl-cysteine, suggesting a pivotal role for ROS in these combinatorial effects. Navitoclax, a senolytic drug that inhibits Bcl-2 proteins, further enhanced the effects of the combination of gemcitabine and IR by strongly inducing apoptotic cell death in senescent cells.ConclusionThese results not only indicate the potential of gemcitabine as a candidate radiosensitizer for malignant meningioma, but also reveal a novel role for gemcitabine radiosensitization as a means to create a therapeutic vulnerability of senescent meningioma cells to senolytics.

Chrysophanol inhibits the osteoglycin/mTOR and activats NF2 signaling pathways to reduce viability and proliferation of malignant meningioma cells

ABSTRACT Chrysophanol shows promising antitumor activity, but how it may work against malignant meningioma is poorly understood. In addition, osteoglycin (OGN) may help mediate the antitumor effects of chrysophanol; thus, this study investigated the potential antitumor mechanism of chrysophanol in malignant meningioma cultures. Meningioma cell line HBL-52 were incubated with varying doses of chrysophanol (0–90 μM) for different time points, and osteoglycin (OGN) was overexpressed or inhibited in some cell cultures to assess its roles. Cell viability was quantified using the CCK8 assay and colony formation assays, while effects on cell cycle distribution and apoptotic rates were examined by flow cytometry and enzyme-linked immunosorbent assays (ELISA) to detect histone DNA levels. Caspase-3 and −9 activities were detected by related commercial kits. Protein expression was assessed using Western blotting. Chrysophanol significantly reduced HBL-52 cell viability, based on reduced colony formation, and proliferation, based on low levels of bromodeoxyuridine incorporation. Annexin V/propidium iodide staining revealed a 30% increase in apoptotic cells at 90 μM chrysophanol (33.7% vs 3.3% in control cultures). Chrysophanol treatment greatly decreased the Bcl-2/Bax expression ratio and increased the expressions of cleaved caspase-3 and −9, and the activities of caspase-3 and −9. Chrysophanol blocked cells in G1 phase and inhibited the OGN/mTOR signaling cascade, but activated neurofibromatosis 2 (NF2) cascade. OGN overexpression activated mTOR, down-regulated NF2, and partially reversed growth inhibition by chrysophanol. Chrysophanol may be useful as a treatment against malignant meningioma by inhibiting OGN/mTOR signaling and activating NF2 signaling.

TB-06 Eribulin prolongs survival in an orthotopic xenograft mouse model of malignant meningioma

Meningioma is the most common intracranial tumor, and its prognosis is typically favorable. However, patients of malignant meningioma (WHO grade III) most often experience recurrence, undergo multiple surgical treatments, and have poor prognosis. No effective therapy for malignant meningioma has been established yet. We recently reported an efficacy of eribulin (Haraven®) for glioblastoma. Eribulin is considered to target TERT, which is frequently mutated in its promoter. Since TERT promoter mutation is also found in malignant meningioma, this study aims at investigating the anti-tumor effect of eribulin against TERT promoter mutation-harboring human malignant meningioma cell lines in vitro and in vivo.Two meningioma cell lines IOMM-Lee and HKBMM were used in this study. In the viability assay and the flow cytometry, eribulin strongly inhibited cell proliferation by cell cycle arrest. Apoptotic cell death in malignant meningioma cell lines was confirmed by vital dye assay and immunoblotting. Moreover, wound healing assay revealed the suppression of tumor cell migration after eribulin exposure. To assess the effect of eribulin in vivo, orthotopic xenograft mouse models of both malignant meningioma cell lines were constructed. The intraperitoneal administration of eribulin significantly prolonged the survival of meningioma cell lines implanted in the brain (p<0.0001). Furthermore, apoptosis was histologically observed in brain tumor tissue by immunohistochemistry.Thus, this study suggests that eribulin is a potential therapeutic agent for treating malignant meningioma.

TB-03 Newly Established Meningioma Organoid Model Elucidated an Important Role of FOXM1 in Meningioma Progression

Meningioma is the most frequently occurring intracranial neoplasms in adults. Tumor removal surgery and radiotherapy were the widely accepted standard treatment for meningioma. Most meningioma cases were cured by extended total removal. However, some tumors develop in locations less amenable to resection, resulting in tumor recurrence after incomplete tumor removal followed by radiotherapy. Although several comprehensive studies have revealed frequently found molecular alterations of meningiomas, effective treatment reagents targeting specific molecular alterations have not been identified yet because of limited number of representative research models such as tumor cell lines or animal models of meningiomas. Recently developed 3D culture technologies have led to the development of novel cancer models, termed organoid models, due to their quite high efficiency of establishment. In this study, we established primary organoid culture methods using malignant meningioma cell lines (e.g. HKBMM and IOMM-Lee) and patient-derived meningioma tissues. Using this novel method, we have been able to establish six organoid models (four WHO grade I meningiomas, one WHO grade III one and one solitary fibrous tumor (SFT)) using tumor tissues derived from six consecutive patients with 100% success rate. Histological analyses, whole exome sequencing and copy number analyses revealed that these organoids exhibited consistent histological features and molecular profiling with those of parental tumors. Using public database, we identified upregulated FOXM1 was correlated with increased tumor proliferation. Over-expression of FOXM1 in benign meningioma organoids increased organoid proliferation, while depletion of FOXM1 in malignant ones decreased their proliferation. We revealed that novel organoid model for meningioma enable to shed light on the tumor biology of meningioma.

EXTH-64. SMALL GTPASES IN MENINGIOMAS: PROLIFERATION, MIGRATION, SURVIVAL, POTENTIAL TREATMENT AND INTERACTIONS

Abstract PURPOSE To evaluate the role of the small GTPases RhoA, Rac1 and Cdc42 in meningiomas as therapeutic targets and their interactions in meningiomas. EXPERIMENTAL DESIGN We analyzed expression of GTPases in human meningioma samples and meningioma cell lines of various WHO grades. Malignant IOMM-Lee meningioma cells were used to generate shRNA mediated knockdowns of GTPases RhoA, Rac1 or Cdc42 and to study knockdown effects on proliferation and migration, as well as analysis of cell morphology by confocal microscopy. The same tests were used to investigate effects of the two inhibitors Fasudil and EHT-1864 of malignant IOMM-Lee, KT21 and benign Ben-Men cells and the effects of these drugs on IOMM-Lee knockdown cells. The effects of GTPase knockdowns and Fasudil treatment were studied in terms of overall survival by intracranial xenografts of mice. Potential interactions of GTPases regarding NF2, mTOR and FAK-Paxillin were examined. RESULTS Small GTPases were upregulated in meningiomas of higher tumor grades. Reduced proliferation and migration could be achieved by GTPase knockdown in IOMM-Lee cells. Additionally, the ROCK-inhibitor Fasudil and Rac1-inhibitor EHT-1864 reduced proliferation in different meningioma cell lines and reduced proliferation and migration independent of GTPase knockdowns/status. Moreover, overall survival in vivo could also be increased by knockdowns of RhoA and Rac1 as well as Fasudil treatment. GTPase expression was affected dependent on the NF2 status but effects were not very distinct, indicating that NF2 is not strongly involved in GTPase regulation in meningiomas. In terms of mTOR and FAK-Paxillin signaling, each GTPase changes those pathways in a different manner. CONCLUSION Small GTPases are important effectors in meningioma proliferation and migration in vitro as well as survival in vivo and their inhibition should be considered as potential treatment option.

EXTH-63. IN VITRO DRUG SCREENING BASED ON IN SILICO DATA IDENTIFIES NEW THERAPEUTIC AGENTS FOR AGGRESSIVE MENINGIOMA

Abstract The mainstay of treatment for progressive or recurrent meningiomas is surgery and/or radiotherapy. Patients with refractory cancer might benefit from systemic treatment options. However, to date, no effective chemotherapy is available for these patients. For this reason, novel inhibitors for the treatment of aggressive meningiomas are urgently needed. Therefore, we used our previously published Affymetrix microarray dataset (GSE74385) consisting of 62 meningiomas enriched with 28 WHO°III MGMs to screen substantially expressed genes that can be targeted by available inhibitors. For each targeted gene, three compounds were selected based on their clinical development. This filter process resulted in 107 drugs targeting 57 different genes. Most compounds were oncology-related (n = 94, 88%) with the remaining compounds being non-oncology agents (n = 13, 12%). Thereafter, a 2-stage screening strategy was employed. First, drugs were screened at a single dose (2.5 µM) in two malignant meningioma cell lines (NCH93 and IOMM-Lee) with CellTiter-Glo (Promega). Only drugs resulting in a cell viability of 50% or less of either cell line were considered for further validation. Remaining drug candidates (n = 33) exclusively belonged to the oncology-related group, consisting of 4 FDA-approved antineoplastic drugs (12%). The other drugs are currently tested in clinical trials (24% in phase III, 39% in phase II, and 24% in phase I). Drug candidates were further analyzed in a six-point dose-response scheme ranging from 0.1 nM to 10 µM in three meningioma cell lines (Ben-Men-1, NCH93, IOMM-Lee). The top 5 drugs were selected based on the lowest mean of z-transformed area under the curve. Resulting drugs and corresponding targets are: OTSSP167 (MELK), Panobinostat (HDAC), Picropodophyllin (IGF-1R), KPT-9274 (PAK4 and NAMPT), and BI-2536 (PLK1). Taken together, our drug screening approach utilized in silico data to identify potential inhibitors for the treatment of aggressive meningiomas warranting further preclinical investigation.

MicroRNA-221/222 Inhibits the Radiation-Induced Invasiveness and Promotes the Radiosensitivity of Malignant Meningioma Cells.

The controversy of adjuvant radiotherapy of meningiomas is at least partially due to the insufficient understanding on meningioma cells' response to irradiation and the shortage of radiosensitivity-promotion methods. MicroRNA-221 and microRNA-222 were identified as critical regulators of radiosensitivity in several other tumors. However, their effect in meningiomas has yet to be confirmed. Therefore, the malignant meningioma IOMM-Lee cells were adopted, transfected with microRNA-221/222 mimics or inhibitors, and irradiated with different dosages. The effects of radiation and microRNA-221/222 were then assessed in vitro and in vivo. Radiation dose increases and microRNA-221/222 downregulation synergistically inhibited cell proliferation and colony formation, prevented xenograft tumor progression, and promoted apoptosis, but antagonistically regulated cell invasiveness. Pairwise comparisons revealed that only high-dose radiations (6 and 8 Gy) can significantly promote cell invasiveness in comparison with unirradiated counterparts. Further comparisons exhibited that downregulating the microRNA-221/222 expression can reverse this radiation-induced cell invasiveness to a level of untransfected and unirradiated cells only if cells were irradiated with no more than 6 Gy. In addition, this approach can promote IOMM-Lee's radiosensitivity. Meanwhile, we also detected that the dose rate of irradiation affects cell cycle distribution and cell apoptosis of IOMM-Lee. A high dose rate irradiation induces G0/G1 cell cycle arrest and apoptosis-promoting effect. Therefore, for malignant meningiomas, high-dose irradiation can facilitate cell invasiveness significantly. Downregulating the microRNA-221/222 level can reverse the radiation-induced cell invasiveness while enhancing the apoptosis-promoting and proliferation-inhibiting effects of radiation and promoting cell radiosensitivity.

Boron Neutron Capture Therapy and Photodynamic Therapy for High-Grade Meningiomas.

Meningiomas are the most common type of intracranial brain tumors in adults. The majority of meningiomas are benign with a low risk of recurrence after resection. However, meningiomas defined as grades II or III, according to the 2016 World Health Organization (WHO) classification, termed high-grade meningiomas, frequently recur, even after gross total resection with or without adjuvant radiotherapy. Boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) are novel treatment modalities for malignant brain tumors, represented by glioblastomas. Although BNCT is based on a nuclear reaction and PDT uses a photochemical reaction, both of these therapies result in cellular damage to only the tumor cells. The aim of this literature review is to investigate the possibility and efficacy of BNCT and PDT as novel treatment modalities for high-grade meningiomas. The present review was conducted by searching PubMed and Scopus databases. The search was conducted in December 2019. Early clinical studies of BNCT have demonstrated activity for high-grade meningiomas, and a phase II clinical trial is in progress in Japan. As for PDT, studies have investigated the effect of PDT in malignant meningioma cell lines to establish PDT as a treatment for malignant meningiomas. Further laboratory research combined with proper controlled trials investigating the effects of these therapies is warranted.

Forkhead Box M1 promotes the growth and tube formation of human malignant meningioma cells via the aryl hydrocarbon receptor signaling pathway.

Forkhead Box M1 (FOXM1) and aryl hydrocarbon receptor (AHR) signaling pathway participate in meningioma development, but their correlation was inadequately studied. The study is aimed to uncover their functions and correlation in malignant meningioma. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect FOXM1 expression in malignant meningioma and adjacent tissues. The viability, proliferation, apoptosis and tube formation of meningioma IOMM-Lee and CH157-MN cells transfected with overexpressed FOXM1 were examined with MTT assay, clone formation assay, flow cytometry and tube formation assay, respectively. The expressions of AHR and cytochrome P450 family 1 subfamily A member 1 (CYP1A1) in meningioma and adjacent tissues were detected using qRT-PCR, and the correlation of AHR with FOXM1 was analyzed with Pearson's correlation analysis. Western blot was conducted for measuring the expressions of vascular endothelial growth factor A (VEGFA), AHR and CYP1A1. The cell viability, proliferation, apoptosis and tube formation capability were further determined after treatment with StemRegenin 1 (SR1) (an AHR signaling pathway inhibitor), and transfected with or without overexpressed FOXM1. FOXM1, AHR and CYP1A1 expressions were upregulated in malignant meningioma tissues. Overexpressed FOXM1 promoted meningioma cell viability, proliferation, tube formation, upregulated expressions of AHR, CYP1A1 and VEGFA, and inhibited the cell apoptosis. AHR was positively correlated with FOXM1. SR1 suppressed meningioma cell growth and the AHR signaling pathway, and also reversed the active effect of FOXM1 on meningioma cells. FOXM1 may promote malignant meningioma via the AHR signaling pathway, which improved the current understanding of the role of FOXM1 in meningioma.

CBMT-06. HIGH LEVELS OF GATA-4 IN MALIGNANT MENINGIOMA LEAD TO LOWER miR-497~195 CLUSTER EXPRESSION IN TISSUE AND BLOOD

Abstract Meningioma is the most common primary intracranial brain tumour, classified as benign (WHO I, 70%), atypical (WHO II, 30%) and anaplastic/malignant (WHO III, 1–3%). The 3-year recurrence rate for WHO I tumours is 40% and it is much higher in WHO II-III1. To date, meningioma classification is based only on histopathological characterization, and no circulating biomarkers have been identified to predict tumour progression2. Indeed, microRNAs are promising circulating biomarkers because they can be released from tumour cells into the blood stream via exosomes, showing potential to be used as liquid biopsies3. Previously, Cyclin D1 overexpression was suggested as a possible meningioma biomarker as it correlates with proliferative activity and tumour grade, while high levels of Cyclin E1 were shown to correlate with higher recurrence rates4,5. In this study, we showed, for the first time, that the transcription factor GATA-4 is overexpressed in malignant meningioma cells and tissues, controlling the miR-15 family (miR-15a/b-16-497-195) expression. Moreover, we proved that the miR-497~195 cluster not only regulates Cyclin D1-D2-D3 and E1 levels, but it also modulates GATA-4 expression in meningioma. Moreover, we showed that the levels of miR-497~195 cluster are significantly lower in exosomes derived from higher grade meningioma patients’ blood serum, supporting their potential as diagnostic biomarkers.

Efficient ADCC killing of meningioma by avelumab and a high-affinity natural killer cell line, haNK.

Meningiomas are the most common adult primary tumor of the central nervous system, but there are no known effective medical therapies for recurrent meningioma, particularly for World Health Organization grade II and III tumors. Meningiomas arise from the meninges, located outside the blood-brain barrier, and therefore may be directly targeted by antibody-mediated immunotherapy. We found that programmed cell death ligand 1 (PD-L1) was highly expressed in multiple human malignant meningioma cell lines and patient tumor samples. PD-L1 was targeted with the anti-PD-L1 antibody avelumab and directed natural killer cells to mediate antibody-dependent cellular cytotoxicity (ADCC) of PD-L1-expressing meningioma tumors both in vitro and in vivo. ADCC of meningioma cells was significantly increased in target cells that upregulated PD-L1 expression and, conversely, abrogated in tumor cells that were depleted of PD-L1. Additionally, the high-affinity natural killer cell line, haNK, outperformed healthy donor NK cells in meningioma ADCC. Together, these data support a clinical trial designed to target PD-L1 with avelumab and haNK cells, potentially offering a novel immunotherapeutic approach for patients with malignant meningioma.

A Monoclonal Antibody Against β1 Integrin Inhibits Proliferation and Increases Survival in an Orthotopic Model of High-Grade Meningioma.

High-grade meningiomas (HGMs; World Health Organization [WHO] classification grade II and III) have high relapse rates and poor clinical outcomes despite surgery and radiation treatments. No effective medical therapy currently exists for HGMs, and developing novel therapeutic strategies depends on the identification of molecular drivers. In cancer, β1 integrin enhances malignant characteristics, including proliferation, invasion, and drug resistance. We conducted this study to investigate whether β1 integrin could be a therapeutic target in HGMs. Expression of β1 integrin was examined in gene array datasets, with proteomics of clinical meningioma specimens, and in patient-derived HGM xenografts. Anti-tumor activity of OS2966, a first-in-class humanized antagonizing monoclonal antibody against β1 integrin, was tested in vitro and in vivo using an orthotopic mouse model of patient-derived malignant meningioma. β1 integrin was expressed in meningiomas of all WHO grades and two xenografts tested. In vitro, OS2966 suppressed the viability of NF2-deficient MN3 sphere cells and NF2-wild-type IOMM-Lee malignant meningioma cells only when plated on laminin-coated plastic. While OS2966 decreased phosphorylation of ERK1/2 in both MN3 cells and laminin-grown IOMM-Lee cells, OS2966 only affected the phosphorylation of FAK (Tyr397) in MN3, and of Akt (Ser473) in IOMM-Lee cells, respectively, indicating differential pathway inhibition. Systemic administration of OS2966 in mice bearing orthotopic MN3 HGMs inhibited HGM cell proliferation and significantly extended overall survival of the treated mice. β1 Integrin may be a therapeutic target in HGMs, and further preclinical and clinical development of OS2966 for HGM therapy is warranted.

Forkhead box M1 (FOXM1) transcription factor is a key oncogenic driver of aggressive human meningioma progression.

Aggressive meningioma remains incurable with neither chemo- nor targeted therapies proven effective, largely due to unidentified genetic alterations and/or aberrant oncogenic pathways driving the disease progression. In this study, we examined the expression and function of Forkhead box M1 (FOXM1) transcription factor during meningioma progression. Human meningioma samples (n=101) were collected, followed by Western blotting, quantitative PCR, immunohistochemical and progression-free survival (PFS) analyses. For in vitro assays, FOXM1 was overexpressed or knocked-down in benign (SF4433 and SF4068) or malignant (SF3061 and IOMM-Lee) human meningioma cell lines respectively. For in vivo studies, siomycin A (a FOXM1 inhibitor)-pretreated or control IOMM-Lee cells were implanted subcutaneously in nude mice. FOXM1 expression was increased in higher grades of meningioma and correlated with the mitotic index in the tumour tissue. Moreover, FOXM1 was increased in recurrent meningioma compared with the matched primary lesions. The patients who had higher FOXM1 expression had shorter PFS. In the subsequent in vitro assays, knockdown of FOXM1 in malignant meningioma cell lines resulted in decreased tumour cell proliferation, angiogenesis and invasion, potentially via regulation of β-catenin, cyclin D1, p21, interleukin-8, vascular endothelial growth factor-A, PLAU, and epithelial-to-mesenchymal transition-related genes, whereas overexpression of FOXM1 in benign meningioma cell lines had the opposite effects. Last, suppression of FOXM1 using a pharmacological inhibitor, siomycin A, decreased tumour growth in an in vivo mouse model. Our data demonstrate that FOXM1 is a key transcription factor regulating oncogenic signalling pathways in meningioma progression, and a promising therapeutic target for aggressive meningioma.

Antitumor Effects of Chrysophanol in Malignant Optic Nerve Meningioma Cell Lines are Mediated via Caspase Activation, Induction of Mitochondrial Mediated Apoptosis, Mitochondrial Membrane Depolarization and Targeting the Mitogen-Activated Protein Kinase Signaling Pathway

Anthroquinones are considered remarkable anticancer agents. Chrysophanol is an important anthroquinone and it has shown to have the potential to inhibit the growth of the range of cancers. However, there are no studies regarding the anticancer effects of chrysophanol against the malignant meningioma of optic nerve. In this review, the potential of chrysophanol in the treatment of malignant -meningioma of optic nerve was explored by evaluating its anticancer activity against the malignant meningioma CH157-MN cells. The 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide assay was used for cell viability determination. The 4',6-diamidino-2-phenylindole (DAPI), acridine orange and ethidium bromide (AO/EB) and annexin V/PI assays were used to determine the induction of apoptosis. The potential of reactive oxygen species and the mitochondrial membrane was estimated by flow cytometry. Western blot analysis was performed to determine the protein expression. The results showed that chrysophanol caused significant decline in the viability of the CH157-MN cells and exhibited an IC50 of 30 µmol/L. Anticancer effects were found to be due to the induction of apoptosis as evident form the DAPI and AO/EB staining. The annexin V/PI staining revealed that the apoptotic cells increased from 1.77% in control to 37.21% at 60 µmol/L concentration of chrysophanol. The Bcl-2/Bax expression ratio was decreased and the caspases-3 and 9 were activated upon chrysophanol treatment of the CH157-MN cells. Chrysophanol also triggered the formation of reactive oxygen species and reduction of the mitochondrial membrane potential in the CH157-MN cells and also blocked the Mitogen-activated protein kinase signaling pathway. The findings of the present study suggest that chrysophanol may prove beneficial in the treatment of malignant meningioma of optic nerve. Key Message: The study revealed the anticancer potential of chrysophanol against the malignant optic nerve meningioma.