Effective Reprogramming of Patient-Derived M2-Polarized Glioblastoma-Associated Microglia/Macrophages by Treatment with GW2580

PURPOSE

Targeting immunosuppressive and pro-tumorigenic glioblastoma (GBM)-associated macrophages and microglial cells (GAM) has great potential to improve patient outcomes. Colony-stimulating factor-1 receptor (CSF1R) has emerged as a promising target for reprograming anti-inflammatory M2-like GAMs. However, treatment data on patient-derived, tumor-educated GAMs and their influence on the adaptive immunity are lacking.

EXPERIMENTAL DESIGN

CD11b+-GAMs freshly isolated from patient tumors were treated with CSF1R-targeting drugs PLX3397, BLZ945, and GW2580. Phenotypical changes upon treatment were assessed using RNA sequencing, flow cytometry, and cytokine quantification. Functional analyses included inducible nitric oxide synthase activity, phagocytosis, transmigration, and autologous tumor cell killing assays. Antitumor effects and changes in GAM activation were confirmed in a complex patient-derived 3D tumor organoid model serving as a tumor avatar.

RESULTS

The most effective reprogramming of GAMs was observed upon GW2580 treatment, which led to the downregulation of M2-related markers, IL6, IL10, ERK1/2, and MAPK signaling pathways, while M1-like markers, gene set enrichment indicating activated MHC-II presentation, phagocytosis, and T-cell killing were substantially increased. Moreover, treatment of patient-derived GBM organoids with GW2580 confirmed successful reprogramming, resulting in impaired tumor cell proliferation. In line with its failure in clinical trials, PLX3397 was ineffective in our analysis.

CONCLUSIONS

This comparative analysis of CSF1R-targeting drugs on patient-derived GAMs and human GBM avatars identified GW2580 as the most powerful inhibitor with the ability to polarize immunosuppressive GAMs to a proinflammatory phenotype, supporting antitumor T-cell responses while also exerting a direct antitumor effect. These data indicate that GW2580 could be an important pillar in future therapies for GBM.

The Antiepileptic Drug Oxcarbazepine Inhibits the Growth of Patient-Derived Isocitrate Dehydrogenase Mutant Glioma Stem-like Cells

Patients diagnosed with isocitrate dehydrogenase mutant (IDH^mut) gliomas suffer frequently from seizures. Although the clinical course is less aggressive than that of its IDH wildtype counterpart, recent discoveries have shown that epileptic activity can promote tumor proliferation. However, it is not known if antiepileptic drugs confer additional value by inhibiting tumor growth. In this study, the antineoplastic properties of 20 FDA-approved antiepileptic drugs (AEDs) were tested in six patient-derived IDH^mut glioma stem-like cells (GSCs). Cell proliferation was assessed using the CellTiterGlo-3D assay. Two of the screened drugs (oxcarbazepine and perampanel) demonstrated an antiproliferative effect. A subsequent eight-point dose-response curve proved the dose-dependent growth inhibition for both drugs, but only oxcarbazepine reached an IC₅₀ value below 100 µM in 5/6 GSCs (mean 44.7 µM; range 17.4-98.0 µM), approximating the possible c_max for oxcarbazepine in patient serums. Furthermore, the treated GSC spheroids were 82% smaller (mean volume 1.6 nL vs. 8.7 nL; p = 0.01 (live/dead^TM fluorescence staining)), and the apoptotic events increased by more than 50% (caspase-3/7 activity; p = 0.006). Taken together, this drug screen of a large series of antiepileptic drugs identified oxcarbazepine as a potent proapoptotic drug in IDH^mut GSCs, which combines antiepileptic and antineoplastic properties to treat this seizure-prone patient population.

Pharmacological Landscape of FDA-Approved Anticancer Drugs Reveals Sensitivities to Ixabepilone, Romidepsin, Omacetaxine, and Carfilzomib in Aggressive Meningiomas

PURPOSE

To date, there are no systemic treatment options for patients with recurrent or refractory meningioma.

EXPERIMENTAL DESIGN

To identify effective drugs, we performed a large-scale drug screening using FDA-approved drugs on several meningioma cell lines. The impact of the top four compounds was assessed on cell viability, proliferation, colony formation, migration, and apoptosis. In addition, the antineoplastic effects of the selected drugs were validated in a heterotopic xenograft mouse model.

RESULTS

Analyses of the viability of meningioma cells treated with 119 antineoplastic FDA-approved drugs resulted in categorization into sensitive and resistant drug-response groups based on the mean IC50 values and peak serum concentrations (Cmax) in patients. Eighty drugs, including 15 alkylating agents, 14 antimetabolites, and 13 tyrosine kinase inhibitors, were classified as resistant (IC50 > Cmax). The sensitive drug-response group (n = 29, IC50 < Cmax) included RNA/protein synthesis inhibitors, proteasome inhibitors, topoisomerase, tyrosine-kinase, and partial histone deacetylase and microtubule inhibitors. The IC50 value of the four most effective compounds (carfilzomib, omacetaxine, ixabepilone, and romidepsin) ranged from 0.12 to 9.5 nmol/L. Most of them caused cell-cycle arrest in the G2-M-phase and induced apoptosis. Furthermore, all drugs except romidepsin significantly inhibited tumor growth in vivo. The strongest antineoplastic effect was observed for ixabepilone, which reduced tumor volume by 86%.

CONCLUSIONS

In summary, a large-scale drug screening provides a comprehensive insight into the anti-meningioma activities of FDA-approved drugs, and identified carfilzomib, omacetaxine, ixabepilone, and romidepsin as novel potent antineoplastic agents for the treatment of aggressive meningiomas. The most pronounced effects were observed with ixabepilone mandating for further clinical investigation.

Preclinical Models of Meningioma

The management of clinically aggressive meningiomas remains challenging due to limited treatment options aside from surgical removal and radiotherapy. High recurrence rates and lack of effective systemic therapies contribute to the unfavorable prognosis of these patients. Accurate in vitro and in vivo models are critical for understanding meningioma pathogenesis and to identify and test novel therapeutics. In this chapter, we review cell models, genetically engineered mouse models, and xenograft mouse models, with special emphasis on the field of application. Finally, promising preclinical 3D models such as organotypic tumor slices and patient-derived tumor organoids are discussed.

MODL-35. A NOVEL PATIENT-DERIVED TUMOR ORGANOID MODEL IDENTIFIES HDACI PANOBINOSTAT AS HIGHLY EFFECTIVE DRUG IN MENINGIOMAS

Tumor-organoids (TOs) are novel, complex three-dimensional ex vivo tissue cultures that under optimal conditions accurately reflect the genotype and phenotype of the original tissue with preserved cellular heterogeneity and morphology. They offer a new and exciting platform for studying cancer biology and directing personalized therapies. Our study aimed to establish TOs from meningioma (MGM) and explore drug responses of selected drugs.TOs were established by controlled reaggregation of freshly prepared single-cell suspension of MGM tissue samples in 384-well plates. We were capable of forming several hundred TO equal in size with a success rate of 98%. TOs consisted of largely viable cells, whereas dead cells were predominantly found outside of the organoid. H&E and IF stainings confirmed the successful establishment of dense tissue-like structures. On the molecular level, transcriptional and mutational profiles were conserved in TOs. To query the suitability and reliability of TOs for robust large-scale drug testing by employing nine highly potent compounds, derived from a drug screening performed on MGM cell lines. In total, standardized TOs from 60 patients were formed, including eight grade II and three grade III MGMs. The FDA-approved epigenetic drug panobinostat demonstrated high anti-meningioma effects in the majority of patients. The efficacy was mediated through inhibition of HDAC1/2 validated by siRNA-mediated knockdown experiments. In an orthotopic in vivo model, treatment with panobinostat extended the median survival of mice, however, the therapy was not curative. To further investigate HDACi resistance, transcriptomes of sensitive and resistant TOs were compared. In resistant tumors, a significant induction of the TGFβ pathway was observed.Taken together, we developed a protocol to generate standardized TO from MGM and preserved histological and molecular features of parental tumor. Drug screening of selected drugs in TOs from 60 patients identified HDACi panobinostat as effective drug through inhibition of HDAC1/2.

MODL-04. ESTABLISHMENT OF A RELIABLE GLIOBLASTOMA TUMOR-ORGANOID PLATFORM ENABLES AUTOMATED HIGH-THROUGHPUT DRUG SCREENING ADVANCING PERSONALIZED MEDICINE

Patient-derived tumor organoids (TOs) generated from tumor tissues within a few days are promising new models since under optimal conditions they preserve genotype, phenotype, the tumor microenvironment and the cellular heterogeneity of the parental tumor. This exciting new technology could provide representative avatars of the patient tumor in large numbers and thus can be exploited for drug discovery and drug screening purposes more efficiently than conventional cell lines or xenografted mouse models. We established standardized TOs from fresh glioblastoma (GBM) tissue after enzymatic dissociation into single cell suspensions and seeding cells into anti-adhesive 384-well plates. Over 1000 standardized TOs were generated per patient with a success rate of over 90%. Morphologically, TOs formed after two days. Size was stable over 10 days, with a slow outgrowth in some cases. A steady increase of the ATP signal over time indicated proliferative activity in TOs. Immunofluorescent stainings for tumor cells (GFAP), immune cells (macrophages and T-cells), and extracellular matrix (Tensascin C) confirmed a strong resemblance of TOs to their corresponding parental tumor, which was further substantiated by RNA-seq and DNA-methylation. Next, automated robot-based high-throughput drug screening (aHTS) on TOs was performed using a drug library of 166 FDA-approved antineoplastic drugs. Cell viability was assessed by CellTiter-Glo3D. In total, aHTS on TOs from 11 GBM patients including two recurrent GBMs showed a strong heterogeneity of drug responses. The top ten best-performing drugs consisted of 35 compounds targeting 14 different modes of action. Proteasome and HDAC-inhibitors demonstrated the highest efficacy. Respective targets were validated by knockdown experiments in GBM cells. Altogether, our data corroborate the future use of standardized GBM TOs as patient avatars for personalized drug testing by utilizing an automated high-throughput drug screening platform to better account for inter-patient-individual drug responses.

IMMU-22. REPROGRAMMING OF MICROGLIA/MACROPHAGES IN GLIOBLASTOMA IMPROVES ANTI-TUMOR T CELL RESPONSES

Glioma-infiltrating myeloid cells such microglia and macrophages (GAM) are a major component of the immunosuppressive tumor microenvironment in glioblastoma (GBM). Especially their anti-inflammatory M2-like activation state might counteract efficacy of immunotherapeutic interventions by impairing effector T cell infiltration and function. Therefore, we studied the ability of the small molecule inhibitors (SMI) PLX3397, BLZ945, and GW2580 that target the M2-associated colony stimulating factor-1 receptor (CSF1R) to shape GAM phenotype towards a pro-inflammatory M1-like phenotype and how this affects the T cell compartment.Upon treatment of freshly isolated CD11b-sorted GBM patient-derived GAMs (n = 15) a decreased expression of CD163 (M2-like) and an increased expression of HLA-DR (M1-like) as well as an increased nitrite production as an indirect measure for iNOS activation (M1-like) was observed which was most pronounced for BLZ945, and GW2580. Transcriptome analysis of treated vs. untreated GAMs supported a reprogramming towards a pro-inflammatory phenotype. In addition, treatment of GAMs in a GBM patient-derived tumor organoid model confirmed a substantial decrease of CD163+ M2-polarized GAM together with a reduced number of proliferating tumor cells. Finally, treatment of patient-derived GAMs led to an increased T cell transmigration through a dense barrier of autologous tumor-derived endothelial cells and increased the ability of T cells to kill autologous tumor cells. Our results support CSF1R blockade is able to reduce the immunosuppressive and pro-tumorigenic functions of GAM substantially and thereby could enhance the effectiveness of T cell-based immunotherapy.

Integrated Molecular-Morphologic Meningioma Classification: A Multicenter Retrospective Analysis, Retrospectively and Prospectively Validated

PURPOSE

Meningiomas are the most frequent primary intracranial tumors. Patient outcome varies widely from benign to highly aggressive, ultimately fatal courses. Reliable identification of risk of progression for individual patients is of pivotal importance. However, only biomarkers for highly aggressive tumors are established (CDKN2A/B and TERT), whereas no molecularly based stratification exists for the broad spectrum of patients with low- and intermediate-risk meningioma.

METHODS

DNA methylation data and copy-number information were generated for 3,031 meningiomas (2,868 patients), and mutation data for 858 samples. DNA methylation subgroups, copy-number variations (CNVs), mutations, and WHO grading were analyzed. Prediction power for outcome was assessed in a retrospective cohort of 514 patients, validated on a retrospective cohort of 184, and on a prospective cohort of 287 multicenter cases.

RESULTS

Both CNV- and methylation family-based subgrouping independently resulted in increased prediction accuracy of risk of recurrence compared with the WHO classification (c-indexes WHO 2016, CNV, and methylation family 0.699, 0.706, and 0.721, respectively). Merging all risk stratification approaches into an integrated molecular-morphologic score resulted in further substantial increase in accuracy (c-index 0.744). This integrated score consistently provided superior accuracy in all three cohorts, significantly outperforming WHO grading (c-index difference P = .005). Besides the overall stratification advantage, the integrated score separates more precisely for risk of progression at the diagnostically challenging interface of WHO grade 1 and grade 2 tumors (hazard ratio 4.34 [2.48-7.57] and 3.34 [1.28-8.72] retrospective and prospective validation cohorts, respectively).

CONCLUSION

Merging these layers of histologic and molecular data into an integrated, three-tiered score significantly improves the precision in meningioma stratification. Implementation into diagnostic routine informs clinical decision making for patients with meningioma on the basis of robust outcome prediction.

DDRE-42. TOWARDS PRECISION MEDICINE: AUTOMATED DRUG SCREENING PLATFORM UTILIZING TUMOR-ORGANOIDS TO IDENTIFY PATIENT-SPECIFIC DRUG-RESPONSES IN MENINGIOMA

Tumor-organoids (TO) are mini-tumors generated from tumor tissue preserving its genotype and phenotype by maintaining the cellular heterogeneity and important components of the tumor microenvironment. We recently developed a protocol to reliably establish TOs from meningioma (MGM) in large quantities. The use of TOs in combination with lab automation holds great promise for drug discovery and screening of comprehensive drug libraries. This might help to tailor patient-specific therapy in the future. The aim of our study was to establish an automated drug screening platform utilizing TOs. For this purpose, we established TOs by controlled reaggregation of freshly prepared single cell suspension of MGM tissue samples in the high-throughput format of 384-well plates. The drug screening was performed fully automated by utilizing the robotic liquid handler Hamilton Microlab STAR and a drug library containing 166 FDA-approved oncology agents. Viability was assessed with CellTiterGlo3D. In total, we performed the drug screening with 166 drugs on TOs from 11 patients suffering from MGM (n=8 WHO°I, n=2 WHO°II, n=1 WHO°III). The top five most effective drugs resulted in a decrease of TO viability ranging from 84.6–63.3%. K-means clustering analysis resulted in groupings of drugs with similar modes of action. One cluster consisted of epigenetic drugs while another cluster consisted of several proteasome inhibitors. However, when looking at a patient-individual level, in 11 patients 44 of 166 drugs, were among the top 10 most effective drugs, providing strong evidence for heterogeneous drug-responses in MGM patients. Taken together, we successfully developed an automated drug screening platform pipeline utilizing TOs from MGM to identify patient-specific drug-responses. The observed intra-individual differences of drug responses mandate for a personalized testing of comprehensive drug libraries in TOs to tailor more effective therapies in MGM patients.

TMOD-29. STANDARDIZED GENERATION OF TUMOR-ORGANOIDS AS NOVEL DRUG SCREENING MODEL IN MENINGIOMA

Tumor-organoids (TOs) are novel, complex three-dimensional ex vivo tissue cultures that under optimal conditions accurately reflect genotype and phenotype of the original tissue with preserved cellular heterogeneity and morphology. They may serve as a new and exciting model for studying cancer biology and directing personalized therapies. The aim of our study was to establish TOs from meningioma (MGM) and to test their usability for large-scale drug screenings. We were capable of forming several hundred TO equal in size by controlled reaggregation of freshly prepared single cell suspension of MGM tissue samples. In total, standardized TOs from 60 patients were formed, including eight grade II and three grade III MGMs. TOs reaggregated within 3 days resulting in a reducted diameter by 50%. Thereafter, TO size remained stable throughout a 14 days observation period. TOs consisted of largely viable cells, whereas dead cells were predominantly found outside of the organoid. H&E stainings confirmed the successful establishment of dense tissue-like structures. Next, we assessed the suitability and reliability of TOs for a robust large-scale drug testing by employing nine highly potent compounds, derived from a drug screening performed on several MGM cell lines. First, we tested if drug responses depend on TO size. Interestingly, drug responses to these drugs remained identical independent of their sizes. Based on a sufficient representation of low abundance cell types such as T-cells and macrophages an overall number of 25.000 cells/TO was selected for further experiments revealing FDA-approved HDAC inhibitors as highly effective drugs in most of the TOs with a mean z-AUC score of -1.33. Taken together, we developed a protocol to generate standardized TO from MGM containing low abundant cell types of the tumor microenvironment in a representative manner. Robust and reliable drug responses suggest patient-derived TOs as a novel drug testing model in meningioma research.

TAMI-61. TUMOR-ASSOCIATED MACROPHAGES ARE INDEPENDENT PROGNOSTIC MARKERS IN MENINGIOMAS

Tumor-associated macrophages (TAMs) play an emerging role in tumor progression by creating an immunosuppressive tumor microenvironment. Therefore, we investigated TAM numbers and their activation (M1/2) in primary (p-) and recurrent (r-) meningiomas and evaluated their impact on survival. Presence of TAMs was analyzed in 195 clinically well-annotated cases (WHO°I n = 43, WHO°II n = 95, WHO°III n = 57; pMGM n = 120, rMGM n = 75). TAMs were quantified by a semiautomated analysis on whole tissue sections stained by multicolor immunofluorescence for CD68 as general TAM marker, and for CD163 and CD204 as M2 marker. CD68+ macrophages positive for either CD163 or CD204 were regarded as M2-polarized TAMs. Furthermore, concentration of 27 immune-relevant cytokines and chemokines from meningioma tissue samples (n = 46) were assessed by Luminex analysis. Median TAM infiltration accounted for 2.47% per total cell count in pMGM and 3.22% in rMGMs. Although no significant WHO°-dependent changes regarding TAM numbers were observed, high numbers of TAMs were associated with shorter progression-free survival (PFS) independent of prognostic confounding variables such as WHO, sex and age. In pMGMs, proportion of M2-polarized TAMs was significantly increased in WHO°II and WHO°III tumors compared to WHO°I (P = 0.001 and P = 0.03, respectively). Luminex data revealed a WHO°-dependent increase of IL-8, IL-10, and IL-12p70. Tissue samples containing higher numbers of TAMs demonstrated significant elevated concentrations of interleukin-1 family members (IL-1β, IL-1Ra), and G-CSF. Furthermore, upregulation of IL-1β and IL-1Ra resulted in shorter overall survival of patients (P = 0.049, P = 0.006, respectively). Taken together, we identified higher numbers of TAMs as an independent prognostic factor for shorter progression-free survival in meningioma patients. This was associated with increased levels of the interleukin-1 family members IL-1β and IL-1Ra and a shorter overall survival, indicating an important function in the tumor microenvironment.

DDRE-30. HIGH-THROUGHPUT DRUG SCREENING OF FDA-APPROVED ANTINEOPLASTIC DRUGS FOR THE TREATMENT OF AGGRESSIVE MENINGIOMAS

The management of aggressive meningiomas remains challenging due to limited treatment options besides surgical removal and radiotherapy. High recurrence rates and lack of effective chemotherapies may be reasons for the unfavorable prognosis of these patients. Consequently, there is an urgent need to identify effective therapeutic agents. For this purpose, we performed a high-throughput screening utilizing a drug library consisting of 147 FDA-approved antineoplastic drugs on the anaplastic meningioma cell line NCH93 using CellTiter-Glo (Promega). Based on the lowest IC50, the top 5 drugs were selected including Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin. Validation of candidate compounds was performed in Ben-Men-1 (grade I), NCH93 (grade III), and IOMM-Lee cells (grade III) using crystal violet assay. Dose-curve analysis revealed IC50 values in the lower nanomolar range for all compounds and all cell lines (0.2 – 16.2 nM). To further substantiate our findings, cell proliferation assessed by manual counting was significantly reduced by up to 90% by each candidate drug at 10xIC50 after 48 h (P &lt; 0.001). Furthermore, cell migration was inhibited up to 60% by all candidate drugs at the respective IC50 (P &lt; 0.05). However, colony formation was only significantly reduced by Bortezomib and Carfilzomib (P &lt; 0.001). The impact of the drugs on cell cycle and apoptosis was analyzed by flow cytometry using Annexin V/PI staining. All candidate drugs induced cell cycle arrest at G0/G1 or G2/M phase (P &lt; 0.001) and subsequently induced apoptosis. Among them, Bortezomib exhibited the most pronounced effect by up to 80% of apoptotic cells (P &lt; 0.001). In summary, by utilizing a high-throughput drug screening we were able to identify Bortezomib, Carfilzomib, Omacetaxine, Ixabepilone, and Romidepsin as potent antineoplastic agents for the treatment of aggressive meningiomas.

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

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.

DDIS-34. HIGH-THROUGHPUT DRUG SCREENING OF FDA-APPROVED ANTINEOPLASTIC DRUGS FOR THE TREATMENT OF AGGRESSIVE MENINGIOMAS

Currently, we are facing several challenges in the treatment of meningiomas: only subtotally removable tumors, high rate of recurrence in higher-grade meningiomas, malignancy, and lack of effective chemotherapeutic agents for aggressive or inoperable tumors. For these reasons, there is an urgent need for more successful treatments for aggressive meningiomas. Therefore, we used 147 FDA-approved antineoplastic drugs on two different meningioma cell lines, including the genetically modified cell line Ben-Men-1 (WHO°I) and the newly established anaplastic meningioma cell line NCH93 (WHO°III). The impact of the drugs on proliferation was assessed in a high-throughput 386-well format with CellTiter-Glo (Promega) and further validation was done by crystal-violet assay. Subsequent screening of 147 FDA-approved drugs resulted in the identification of potential 5 drugs, including Bortezomib, Carfilzomib, Omacetaxine, Paclitaxel, and Ponatinib. Dose-curve analysis revealed IC50 values of these drugs in the Ben-Men-1 and NCH93 cell lines as follows: Bortezomib 16.2 and 5.7 nM, Carfilzomib 4.8 and 2.6 nM, Omacetaxine and 5.0 and 8.9 nM, Paclitaxel 2.6 and 1.9 µM, and Ponatinib 278 and 206 nM. Inhibitor dosage of 10xIC50 values and higher lead to an average inhibition of Ben-Men-1 and NCH93 cells by up to 90% on day 2 (P< .001). The impact of the antineoplastic agents on the cell cycle was analyzed by flow cytometry. Percentages of sub-G1 phase were significantly elevated with increasing drug concentrations of all five tested compounds (P< .001). To assess the effects of the drugs on migration scratch assay was performed. Drug concentrations of 10xIC50 values resulted in an inhibition of migration in Ben-Men-1 cells for Bortezomib, Carfilzomib, and Omacetaxine by 49%, 30%, and 23%, respectively (P< .05). In conclusion, we identified 5 promising drugs for the treatment of aggressive meningiomas by applying a high-throughput drug screening of 147 FDA-approved antineoplastic drugs.

Overexpression of minichromosome maintenance protein 10 in medulloblastoma and its clinical implications

BACKGROUND

Overexpression of minichromosome maintenance (MCM) proteins 2, 3, and 7 is associated with migration and invasion in medulloblastoma (MB). However, expression profiling of all prereplication complex (pre-RC) has not been addressed in MBs.

PROCEDURE

We performed mRNA expression profiling of a large set of pre-RC elements in cell lines and tumor tissues of MB. RNAi technology was employed for functional studies in MB cell lines.

RESULTS

Our data showed that most of the pre-RC components are significantly overexpressed in MB. Among all pre-RC mRNAs, MCM10 showed the highest level of expression (∼500- to 1,000-fold) in MB cell lines and tissues compared to the levels detected in cerebellum. In addition, RNAi silencing of MCM10 caused reduced cell proliferation and cell viability in MB cells.

CONCLUSIONS

Taken together, our study reveals that the pre-RC is dysregulated in MB. In addition, MCM10, a member of this complex, is significantly overexpressed in MB and is required for tumor cell proliferation.