Publications by authors named "Christel Herold-Mende"

266 Publications

Radioresistance and transcriptional reprograming of invasive glioblastoma cells.

Int J Radiat Oncol Biol Phys 2021 Sep 14. Epub 2021 Sep 14.

Division of Molecular & Translational Radiation Oncology, Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital (UKHD), Heidelberg, Germany; Cancer Consortium (DKTK) Core-Center, German Cancer Research Center (DKFZ), Heidelberg, Germany; Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Oncology (NCRO), German Cancer Research Center (DKFZ), Heidelberg University Hospital (UKHD), Faculty of Medicine (MFHD) of the Heidelberg University, and Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg, Germany; CCU Translational Radiation Oncology, CCU Radiation Oncology, CCU Neurooncology, National Center for Tumor Diseases (NCT) German Cancer Research Center (DKFZ), Heidelberg University Hospital (UKHD), Heidelberg, Germany; Departments of Neurology, Neurosurgery and Radiation Oncology, Heidelberg University Hospital (UKHD), Heidelberg, Germany. Electronic address:

Purpose: Infiltrative growth pattern is a hallmark of glioblastoma (GBM). Radiotherapy aims to eradicate microscopic residual GBM cells post-surgical removal of the visible tumor bulk. However, in field recurrences remain the major pattern of therapy failure. We hypothesized that the radiosensitivity of peripheral invasive tumor cells (peri) may differ from predominantly investigated tumor bulk.

Material And Methods: Invasive GBM populations were generated via debulking of the visible tumor core and serial orthotopic transplantation of peri cells and sustained pro-invasive phenotype of peri cell was confirmed in-vitro by scratch assay and time lapse imaging. In parallel, invasive GBM cells were selected by transwell assay and from peri cells of patient derived 3D spheroid cultures. Transcriptome analysis deciphered a GBM invasion associated gene signature and functional involvement of key pathways was validated by pharmacological inhibition.

Results: Compared to the bulk cells, invasive GBM populations acquired a radioresistant phenotype characterized by increased cell survival, reduced cell apoptosis and enhanced DNA double strand break (DSB) repair proficiency. Transcriptome analysis revealed a reprograming of invasive cells towards augmented activation of EGFR and NF-κB related pathways while metabolic processes were downregulated. An invasive GBM score (iGS) derived from this transcriptional fingerprint correlated well with patient outcome. Inhibition of EGFR and NF-κB signaling re-sensitized invasive cells to irradiation. Invasive cells were eradicated with similar efficacy by particle therapy with carbon ions.

Conclusions: Our data indicate that invasive tumor cells constitute a phenotypically distinct and highly radioresistant GBM subpopulation with prognostic impact that may be vulnerable to targeted therapy and carbon-ions.
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http://dx.doi.org/10.1016/j.ijrobp.2021.09.017DOI Listing
September 2021

XAB2 promotes Ku eviction from single-ended DNA double-strand breaks independently of the ATM kinase.

Nucleic Acids Res 2021 Sep 9. Epub 2021 Sep 9.

DNA Repair and Chemoresistance Group, Department of Oncology, Luxembourg Institute of Health (LIH), Luxembourg, Luxembourg.

Replication-associated single-ended DNA double-strand breaks (seDSBs) are repaired predominantly through RAD51-mediated homologous recombination (HR). Removal of the non-homologous end-joining (NHEJ) factor Ku from resected seDSB ends is crucial for HR. The coordinated actions of MRE11-CtIP nuclease activities orchestrated by ATM define one pathway for Ku eviction. Here, we identify the pre-mRNA splicing protein XAB2 as a factor required for resistance to seDSBs induced by the chemotherapeutic alkylator temozolomide. Moreover, we show that XAB2 prevents Ku retention and abortive HR at seDSBs induced by temozolomide and camptothecin, via a pathway that operates in parallel to the ATM-CtIP-MRE11 axis. Although XAB2 depletion preserved RAD51 focus formation, the resulting RAD51-ssDNA associations were unproductive, leading to increased NHEJ engagement in S/G2 and genetic instability. Overexpression of RAD51 or RAD52 rescued the XAB2 defects and XAB2 loss was synthetically lethal with RAD52 inhibition, providing potential perspectives in cancer therapy.
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http://dx.doi.org/10.1093/nar/gkab785DOI Listing
September 2021

Calcitriol Promotes Differentiation of Glioma Stem-Like Cells and Increases Their Susceptibility to Temozolomide.

Cancers (Basel) 2021 Jul 16;13(14). Epub 2021 Jul 16.

Neuroscience Center, Experimental Neurosurgery, Department of Neurosurgery, Goethe University, 60590 Frankfurt am Main, Germany.

Glioblastoma (GBM) is the most common and most aggressive primary brain tumor, with a very high rate of recurrence and a median survival of 15 months after diagnosis. Abundant evidence suggests that a certain sub-population of cancer cells harbors a stem-like phenotype and is likely responsible for disease recurrence, treatment resistance and potentially even for the infiltrative growth of GBM. GBM incidence has been negatively correlated with the serum levels of 25-hydroxy-vitamin D, while the low pH within tumors has been shown to promote the expression of the vitamin D-degrading enzyme 24-hydroxylase, encoded by the gene. Therefore, we hypothesized that calcitriol can specifically target stem-like glioblastoma cells and induce their differentiation. Here, we show, using in vitro limiting dilution assays, quantitative real-time PCR, quantitative proteomics and ex vivo adult organotypic brain slice transplantation cultures, that therapeutic doses of calcitriol, the hormonally active form of vitamin D, reduce stemness to varying extents in a panel of investigated GSC lines, and that it effectively hinders tumor growth of responding GSCs ex vivo. We further show that calcitriol synergizes with Temozolomide ex vivo to completely eliminate some GSC tumors. These findings indicate that calcitriol carries potential as an adjuvant therapy for a subgroup of GBM patients and should be analyzed in more detail in follow-up studies.
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http://dx.doi.org/10.3390/cancers13143577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8303292PMC
July 2021

Chemoradiotherapy but Not Radiotherapy Alone for Larynx Preservation in T3. Considerations from a German Observational Cohort Study.

Cancers (Basel) 2021 Jul 8;13(14). Epub 2021 Jul 8.

Heidelberg Institute of Global Health, University of Heidelberg, 69120 Heidelberg, Germany.

For advanced laryngeal cancers, after randomized prospective larynx preservation studies, nonsurgical therapy has been applied on a large scale as an alternative to laryngectomy. For T4 laryngeal cancer, poorer survival has been reported after nonsurgical treatment. Is there a need to fear worse survival also in T3 tumors? The outcomes of 121 T3 cancers treated with pCRT, pRT alone, or surgery were evaluated in an observational cohort study in Germany. In a multivariate Cox regression of the T3 subgroup, no survival difference was noted between pCRT and total laryngectomy with risk-adopted adjuvant (chemo)radiotherapy (TL ± a(C)RT) (HR 1.20; 95%-CI: 0.57-2.53; = 0.63). However, survival was significantly worse after pRT alone than after TL ± a(C)RT (HR 4.40; 95%-CI: 1.72-11.28, = 0.002). A literature search shows that in cases of unfavorable prognostic markers (bulky tumors of 6-12 ccm, vocal cord fixation, minimal cartilage infiltration, or N2-3), pCRT instead of pRT is indicated. In cases of pretreatment dysphagia or aspiration requiring a feeding tube or tracheostomy, gross or multiple cartilage infiltration, or tumor volume > 12 ccm, outcomes after pCRT were significantly worse than those after TL. In these cases, and in cases where pCRT is indicated but the patient is not suitable for the addition of chemotherapy, upfront total laryngectomy with stage-appropriate aRT is recommended even in T3 laryngeal cancers.
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http://dx.doi.org/10.3390/cancers13143435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306673PMC
July 2021

Cystathionine-γ-lyase drives antioxidant defense in cysteine-restricted IDH1-mutant astrocytomas.

Neurooncol Adv 2021 Jan-Dec;3(1):vdab057. Epub 2021 Apr 9.

NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.

Background: Mutations in isocitrate dehydrogenase 1 or 2 () define glioma subtypes and are considered primary events in gliomagenesis, impacting tumor epigenetics and metabolism. IDH enzyme activity is crucial for the generation of reducing potential in normal cells, yet the impact of the mutation on the cellular antioxidant system in glioma is not understood. The aim of this study was to determine how glutathione (GSH), the main antioxidant in the brain, is maintained in IDH1-mutant gliomas, despite an altered NADPH/NADP balance.

Methods: Proteomics, metabolomics, metabolic tracer studies, genetic silencing, and drug targeting approaches in vitro and in vivo were applied. Analyses were done in clinical specimen of different glioma subtypes, in glioma patient-derived cell lines carrying the endogenous IDH1 mutation and corresponding orthotopic xenografts in mice.

Results: We find that cystathionine-γ-lyase (CSE), the enzyme responsible for cysteine production upstream of GSH biosynthesis, is specifically upregulated in IDH1-mutant astrocytomas. CSE inhibition sensitized these cells to cysteine depletion, an effect not observed in IDH1 wild-type gliomas. This correlated with an increase in reactive oxygen species and reduced GSH synthesis. Propargylglycine (PAG), a brain-penetrant drug specifically targeting CSE, led to delayed tumor growth in mice.

Conclusions: e show that IDH1-mutant astrocytic gliomas critically rely on NADPH-independent de novo GSH synthesis via CSE to maintain the antioxidant defense, which highlights a novel metabolic vulnerability that may be therapeutically exploited.
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http://dx.doi.org/10.1093/noajnl/vdab057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8262642PMC
April 2021

A novel patient stratification strategy to enhance the therapeutic efficacy of dasatinib in glioblastoma.

Neuro Oncol 2021 Jul 7. Epub 2021 Jul 7.

Brain Tumor Translational Targets, DKFZ Junior Group, German Cancer Research Center (DKFZ), Heidelberg, Germany.

Background: Glioblastoma is the most common primary malignancy of the central nervous system with dismal prognosis. Genomic signatures classify isocitrate dehydrogenase 1 (IDH)-wildtype glioblastoma into three subtypes: proneural, mesenchymal and classical. Dasatinib, an inhibitor of proto-oncogene kinase Src (SRC), is one of many therapeutics which, despite promising preclinical results, has failed to improve overall survival in glioblastoma patients in clinical trials. We examined whether glioblastoma subtypes differ in their response to dasatinib and could hence be evaluated for patient enrichment strategies in clinical trials.

Methods: We carried out in silico analyses on glioblastoma gene expression (TCGA) and single-cell RNA-Seq data. In addition, in vitro experiments using glioblastoma stem-like cells (GSCs) derived from primary patient tumors were performed, with complementary gene expression profiling and immunohistochemistry analysis of tumor samples.

Results: Patients with the mesenchymal subtype of glioblastoma showed higher SRC pathway activation based on gene expression profiling. Accordingly, mesenchymal GSCs were more sensitive to SRC inhibition by dasatinib compared to proneural and classical GSCs. Notably, SRC phosphorylation status did not predict response to dasatinib treatment. Furthermore, serpin peptidase inhibitor clade H member 1 (SERPINH1), a collagen related heat-shock protein associated with cancer progression, was shown to correlate with dasatinib response and with the mesenchymal subtype.

Conclusion: This work highlights further molecular-based patient selection strategies in clinical trials and suggests the mesenchymal subtype as well as SERPINH1 to be associated with response to dasatinib. Our findings indicate that stratification based on gene expression subtyping should be considered in future dasatinib trials.
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http://dx.doi.org/10.1093/neuonc/noab158DOI Listing
July 2021

A New Pentafluorothio-Substituted Curcuminoid with Superior Antitumor Activity.

Biomolecules 2021 06 25;11(7). Epub 2021 Jun 25.

Experimental Neurosurgery, Frankfurt University Hospital, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.

A new and readily available pentafluorothiophenyl-substituted N-methyl-piperidone curcuminoid was prepared and investigated for its anti-proliferative, pro-apoptotic and cancer stem cell-differentiating activities against a panel of human tumor cell lines derived from various tumor entities. The compound was highly anti-proliferative and reached IC values in the nanomolar concentration range. was superior to the known anti-tumorally active curcuminoid EF24 () and its known N-ethyl-piperidone analog in all tested tumor cell lines. Furthermore, induced a noticeable increase of intracellular reactive oxygen species in HT-29 colon adenocarcinoma cells, which possibly leads to a distinct increase in sub-G1 cells, as assessed by cell cycle analysis. A considerable activation of the executioner-caspases 3 and 7 as well as nuclei fragmentation, cell rounding, and membrane protrusions suggest the triggering of an apoptotic mechanism. Yet another effect was the re-organization of the actin cytoskeleton shown by the formation of stress fibers and actin aggregation. also caused cell death in the adherently cultured glioblastoma cell lines U251 and Mz54. We furthermore observed that strongly suppressed the stem cell properties of glioma stem-like cell lines including one primary line, highlighting the potential therapeutic relevance of this new compound.
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http://dx.doi.org/10.3390/biom11070947DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8301868PMC
June 2021

Cross-Species Genomics Reveals Oncogenic Dependencies in ZFTA/C11orf95 Fusion-Positive Supratentorial Ependymomas.

Cancer Discov 2021 Sep 20;11(9):2230-2247. Epub 2021 Apr 20.

Department of Neuropathology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.

Molecular groups of supratentorial ependymomas comprise tumors with or -involving fusions and fusion-negative subependymoma. However, occasionally supratentorial ependymomas cannot be readily assigned to any of these groups due to lack of detection of a typical fusion and/or ambiguous DNA methylation-based classification. An unbiased approach with a cohort of unprecedented size revealed distinct methylation clusters composed of tumors with ependymal but also various other histologic features containing alternative translocations that shared as a partner gene. Somatic overexpression of -associated fusion genes in the developing cerebral cortex is capable of inducing tumor formation , and cross-species comparative analyses identified as a key downstream regulator of tumorigenesis in all tumors. Targeting GLI2 with arsenic trioxide caused extended survival of tumor-bearing animals, indicating a potential therapeutic vulnerability in ZFTA fusion-positive tumors. SIGNIFICANCE: fusions are a hallmark feature of supratentorial ependymoma. We find that ZFTA acts as a partner for alternative transcriptional activators in oncogenic fusions of supratentorial tumors with various histologic characteristics. Establishing representative mouse models, we identify potential therapeutic targets shared by fusion-positive tumors, such as GLI2..
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http://dx.doi.org/10.1158/2159-8290.CD-20-0963DOI Listing
September 2021

Cannabidiol converts NFκB into a tumor suppressor in glioblastoma with defined antioxidative properties.

Neuro Oncol 2021 Apr 17. Epub 2021 Apr 17.

Neurosurgical Research, Department of Neurosurgery, University Hospital, LMU Munich, Germany.

Background: The transcription factor NFκB drives neoplastic progression of many cancers including primary brain tumors (glioblastoma; GBM). Precise therapeutic modulation of NFκB activity can suppress central oncogenic signalling pathways in GBM, but clinically applicable compounds to achieve this goal have remained elusive.

Methods: In a pharmacogenomics study with a panel of transgenic glioma cells we observed that NFκB can be converted into a tumor suppressor by the non-psychotropic cannabinoid Cannabidiol (CBD). Subsequently, we investigated the anti-tumor effects of CBD, which is used as an anticonvulsive drug (Epidiolex) in pediatric neurology, in a larger set of human primary GBM stem-like cells (hGSC). For this study we performed pharmacological assays, gene expression profiling, biochemical and cell-biological experiments. We validated our findings using orthotopic in vivo models and bioinformatics analysis of human GBM-datasets.

Results: We found that CBD promotes DNA binding of the NFκB subunit RELA and simultaneously prevents RELA-phosphorylation on serine-311, a key residue which permits genetic transactivation. Strikingly, sustained DNA binding by RELA lacking phospho-serine 311 was found to mediate hGSC cytotoxicity. Widespread sensitivity to CBD was observed in a cohort of hGSC defined by low levels of reactive oxygen-species (ROS), while high ROS-content in other tumors blocked CBD induced hGSC death. Consequently, ROS levels served as predictive biomarker for CBD-sensitive tumors.

Conclusions: This evidence demonstrates how a clinically approved drug can convert NFκB into a tumor suppressor and suggests a promising repurposing option for GBM-therapy.
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http://dx.doi.org/10.1093/neuonc/noab095DOI Listing
April 2021

Integrated Metabolomics and Transcriptomics Analysis of Monolayer and Neurospheres from Established Glioblastoma Cell Lines.

Cancers (Basel) 2021 Mar 16;13(6). Epub 2021 Mar 16.

Cancer Signalling and Metabolism Group, Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, 4200-135 Porto, Portugal.

Altered metabolic processes contribute to carcinogenesis by modulating proliferation, survival and differentiation. Tumours are composed of different cell populations, with cancer stem-like cells being one of the most prominent examples. This specific pool of cells is thought to be responsible for cancer growth and recurrence and plays a particularly relevant role in glioblastoma (GBM), the most lethal form of primary brain tumours. Here, we have analysed the transcriptome and metabolome of an established GBM cell line (U87) and a patient-derived GBM stem-like cell line (NCH644) exposed to neurosphere or monolayer culture conditions. By integrating transcriptome and metabolome data, we identified key metabolic pathways and gene signatures that are associated with stem-like and differentiated states in GBM cells, and demonstrated that neurospheres and monolayer cells differ substantially in their metabolism and gene regulation. Furthermore, arginine biosynthesis was identified as the most significantly regulated pathway in neurospheres, although individual nodes of this pathway were distinctly regulated in the two cellular systems. Neurosphere conditions, as opposed to monolayer conditions, cause a transcriptomic and metabolic rewiring that may be crucial for the regulation of stem-like features, where arginine biosynthesis may be a key metabolic pathway. Additionally, TCGA data from GBM patients showed significant regulation of specific components of the arginine biosynthesis pathway, providing further evidence for the importance of this metabolic pathway in GBM.
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http://dx.doi.org/10.3390/cancers13061327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8001840PMC
March 2021

Could Primary Chemoradiotherapy in T2 Glottic Cancers Yield Results Comparable to Primary Radiotherapy in T1? Considerations from 531 German Early Stage Patients.

Cancers (Basel) 2021 Mar 31;13(7). Epub 2021 Mar 31.

Heidelberg Institute of Global Health, University of Heidelberg, 69120 Heidelberg, Germany.

T1 glottic cancer is a highly treatable disease with local control (LC) rates over 90% by either primary radiotherapy (pRT) or transoral laser microsurgery (TLM). LC of T2 glottic cancers is 15 percent points poorer on average. However, salvage after pRT entails more than 50% total laryngectomy. Therefore, there is a need for enhanced LC. Altered fractionation regimens improved LC in T1 but not in T2. For this reason, for T2, alternative strategies must be considered. In a large observational cohort study including 531 early-stage laryngeal cancers, a small number of patients were treated with primary chemoradiotherapy (pCRT). In multivariable analysis, factors associated with significantly poorer outcomes included age, comorbidities, supraglottic localization, and T category. While there was a significant difference between pRT and surgery (HR 1.79; 95%-CI: 1.15-2.79), there was none between pCRT and surgery (HR 0.70; 95%-CI: 0.33-1.51). There is evidence from the literature that pCRT in early glottic cancers could yield results that surpass the limits so far experienced in radiotherapy alone with acceptable toxicity. Thus, prospective randomized studies with larger numbers of patients are warranted.
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http://dx.doi.org/10.3390/cancers13071601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8037641PMC
March 2021

Prognostic Value of microRNA-221/2 and 17-92 Families in Primary Glioblastoma Patients Treated with Postoperative Radiotherapy.

Int J Mol Sci 2021 Mar 15;22(6). Epub 2021 Mar 15.

German Cancer Consortium (DKTK) Core-Center, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.

MicroRNAs (miRs) are non-coding master regulators of transcriptome that could act as tumor suppressors (TSs) or oncogenes (oncomiRs). We aimed to systematically investigate the relevance of miRs as prognostic biomarkers in primary glioblastoma multiforme (GBM) treated with postoperative radio(chemo)therapy (PORT). For hypothesis generation, tumor miR expression by Agilent 8x15K human microRNA microarrays and survival data from 482 GBM patients of The Cancer Genome Atlas (TCGA cohort) were analyzed using Cox-PH models. Expression of candidate miRs with prognostic relevance (miR-221/222; miR-17-5p, miR-18a, miR-19b) was validated by qRT-PCR using Taqman technology on an independent validation cohort of GBM patients ( = 109) treated at Heidelberg University Hospital (HD cohort). In TCGA, 50 miRs showed significant association with survival. Among the top ranked prognostic miRs were members of the two miR families miR-221/222 and miR-17-92. Loss of miR-221/222 was correlated with improved prognosis in both cohorts (TCGA, HD) and was an independent prognostic marker in a multivariate analysis considering demographic characteristics (age, sex, Karnofsky performance index (KPI)), molecular markers (O-6-methylguanine-DNA methyltransferase (MGMT) methylation, IDH mutation status) and PORT as co-variables. The prognostic value of miR-17-92 family members was ambiguous and in part contradictory by direct comparison of the two cohorts, thus warranting further validation in larger prospective trials.
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http://dx.doi.org/10.3390/ijms22062960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998975PMC
March 2021

KIF11 inhibitors filanesib and ispinesib inhibit meningioma growth in vitro and in vivo.

Cancer Lett 2021 05 27;506:1-10. Epub 2021 Feb 27.

Division of Experimental Neurosurgery, Department of Neurosurgery, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. Electronic address:

Treatment of aggressive meningiomas remains challenging due to a high rate of recurrence in higher-grade meningiomas, frequent subtotal resections, and the lack of effective systemic treatments. Substantial overexpression associated with a poor prognosis has been demonstrated for kinesin family member 11 (KIF11) in high-grade meningiomas. Due to anti-tumor activity for KIF11 inhibitors (KIF11i) filanesib and ispinesib in other cancer types, we sought to investigate their mode of action and efficacy for the treatment of aggressive meningiomas. Dose curve analysis of both KIF11i revealed IC50 values of less than 1 nM in anaplastic and benign meningioma cell lines. Both compounds induced G2/M arrest and subsequent subG1 increase in all cell lines. Profound induction of apoptosis was detected in the anaplastic cell lines determined by annexin V staining. KIF11i significantly inhibited meningioma growth in xenotransplanted mice by up to 83%. Furthermore, both drugs induced minor hematological side effects, which were less pronounced for filanesib. We identified substantial in vitro and in vivo anti-tumor effects of the KIF11 inhibitors filanesib and ispinesib, with filanesib demonstrating better tolerability, suggesting future use of filanesib for the treatment of aggressive meningioma.
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http://dx.doi.org/10.1016/j.canlet.2021.02.016DOI Listing
May 2021

An Observational Cohort Study on 194 Supraglottic Cancer Patients: Implications for Laser Surgery and Adjuvant Treatment.

Cancers (Basel) 2021 Feb 2;13(3). Epub 2021 Feb 2.

Heidelberg Institute of Global Health, University of Heidelberg, 69120 Heidelberg, Germany.

Supraglottic laryngeal cancer is characterized by poor prognosis. In contrast, excellent outcomes have been published in early-stage supraglottic cancers after laser surgery in single-institutional series in centers of excellence. Are these results reproducible in the normal clinical practice of less specialized facilities? As part of an observational cohort study, the outcomes of 194 supraglottic cancer patients were assessed after treatment by larynx-preserving surgery (transoral laser microsurgery [TLM] or open partial laryngectomy [OPL]) or total laryngectomy (TL), with each having risk-adopted adjuvant treatment, or primary (chemo-)radiotherapy (pCRT or pRT). In early-stage supraglottic cancers, TLM achieved a 5-year overall survival (5-year OS) of 62.0%. No significant survival difference could be discerned between patients with and without adjuvant treatment (HR 1.47; 95% CI: 0.80 2.69). The comparison between pCRT and pRT patients suggests that CRT is more effective in supraglottic cancer. The 5-year OS rate achieved in our multiinstitutional setting is comparable to that reached in laser surgery centers of excellence (59.4-76.0%). According to our data and supported by the literature, adjuvant RT (aRT) is not sufficiently effective in supraglottic cancers. In case adjuvant therapy is indicated, adjuvant chemoradiation (aCRT) could be recommended.
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http://dx.doi.org/10.3390/cancers13030568DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7867201PMC
February 2021

IDH1 mutations induce organelle defects via dysregulated phospholipids.

Nat Commun 2021 01 27;12(1):614. Epub 2021 Jan 27.

Neuro-Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, MD, USA.

Infiltrating gliomas are devastating and incurable tumors. Amongst all gliomas, those harboring a mutation in isocitrate dehydrogenase 1 mutation (IDH1) acquire a different tumor biology and clinical manifestation from those that are IDH1. Understanding the unique metabolic profile reprogrammed by IDH1 mutation has the potential to identify new molecular targets for glioma therapy. Herein, we uncover increased monounsaturated fatty acids (MUFA) and their phospholipids in endoplasmic reticulum (ER), generated by IDH1 mutation, that are responsible for Golgi and ER dilation. We demonstrate a direct link between the IDH1 mutation and this organelle morphology via D-2HG-induced stearyl-CoA desaturase (SCD) overexpression, the rate-limiting enzyme in MUFA biosynthesis. Inhibition of IDH1 mutation or SCD silencing restores ER and Golgi morphology, while D-2HG and oleic acid induces morphological defects in these organelles. Moreover, addition of oleic acid, which tilts the balance towards elevated levels of MUFA, produces IDH1-specific cellular apoptosis. Collectively, these results suggest that IDH1-induced SCD overexpression can rearrange the distribution of lipids in the organelles of glioma cells, providing new insight into the link between lipid metabolism and organelle morphology in these cells, with potential and unique therapeutic implications.
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http://dx.doi.org/10.1038/s41467-020-20752-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7840755PMC
January 2021

Unique challenges for glioblastoma immunotherapy-discussions across neuro-oncology and non-neuro-oncology experts in cancer immunology. Meeting Report from the 2019 SNO Immuno-Oncology Think Tank.

Neuro Oncol 2021 03;23(3):356-375

Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California.

Cancer immunotherapy has made remarkable advances with over 50 separate Food and Drug Administration (FDA) approvals as first- or second-line indications since 2015. These include immune checkpoint blocking antibodies, chimeric antigen receptor-transduced T cells, and bispecific T-cell-engaging antibodies. While multiple cancer types now benefit from these immunotherapies, notable exceptions thus far include brain tumors, such as glioblastoma. As such, it seems critical to gain a better understanding of unique mechanistic challenges underlying the resistance of malignant gliomas to immunotherapy, as well as to acquire insights into the development of future strategies. An Immuno-Oncology Think Tank Meeting was held during the 2019 Annual Society for Neuro-Oncology Scientific Conference. Discussants in the fields of neuro-oncology, neurosurgery, neuro-imaging, medical oncology, and cancer immunology participated in the meeting. Sessions focused on topics such as the tumor microenvironment, myeloid cells, T-cell dysfunction, cellular engineering, and translational aspects that are critical and unique challenges inherent with primary brain tumors. In this review, we summarize the discussions and the key messages from the meeting, which may potentially serve as a basis for advancing the field of immune neuro-oncology in a collaborative manner.
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http://dx.doi.org/10.1093/neuonc/noaa277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7992879PMC
March 2021

The anesthetist's choice of inhalational vs. intravenous anesthetics has no impact on survival of glioblastoma patients.

Neurosurg Rev 2020 Dec 22. Epub 2020 Dec 22.

Division of Neurosurgical Research, Department of Neurosurgery, University Hospital Heidelberg, Heidelberg, Germany.

Recent data suggest that the type of anesthesia used during the resection of solid tumors impacts the long-term survival of patients favoring total-intravenous-anesthesia (TIVA) over inhalative-anesthesia (INHA). Here we sought to query this impact on survival in patients undergoing resection of glioblastoma (GBM). All patients receiving elective resection of a newly diagnosed, isocitrate-dehydrogenase-1-(IDH1)-wildtype GBM under general anesthesia between January 2010 and June 2017 in the Department of Neurosurgery, Heidelberg University Hospital, were included. Patients were grouped according to the applied anesthetic technique. To adjust for potential prognostic confounders, patients were matched in a 1:2 ratio (TIVA vs. INHA), taking into account the known prognostic factors: age, extent of resection, O-6-methylguanine-DNA-methyltransferase-(MGMT)-promoter-methylation-status, pre-operative Karnofsky-performance-index and adjuvant radio- and chemotherapy. The primary endpoint was progression-free-survival (PFS) and the secondary endpoint was overall-survival (OS). In the study period, 576 patients underwent resection of a newly diagnosed, IDH-wildtype GBM. Patients with incomplete follow-up-data, on palliative treatment, having emergency or awake surgery; 54 patients remained in the TIVA-group and 417 in the INHA-group. After matching, 52 patients remained in the TIVA-group and 92 in the INHA-group. Median PFS was 6 months in both groups. The median OS was 13.5 months in the TIVA-group and 13.0 months in the INHA-group. No significant survival differences associated with the type of anesthesia were found either before or after adjustment for known prognostic factors. This retrospective study supports the notion that the current anesthetic approaches employed during the resection of IDH-wildtype GBM do not impact patient survival.
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http://dx.doi.org/10.1007/s10143-020-01452-7DOI Listing
December 2020

Clear cell meningiomas are defined by a highly distinct DNA methylation profile and mutations in SMARCE1.

Acta Neuropathol 2021 02 14;141(2):281-290. Epub 2020 Dec 14.

Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA.

Clear cell meningioma represents an uncommon variant of meningioma that typically affects children and young adults. Although an enrichment of loss-of-function mutations in the SMARCE1 gene has been reported for this subtype, comprehensive molecular investigations are lacking. Here we describe a molecularly distinct subset of tumors (n = 31), initially identified through genome-wide DNA methylation screening among a cohort of 3093 meningiomas, of which most were diagnosed histologically as clear cell meningioma. This cohort was further supplemented by an additional 11 histologically diagnosed clear cell meningiomas for analysis (n = 42). Targeted DNA sequencing revealed SMARCE1 mutations in 33/34 analyzed samples, accompanied by a nuclear loss of expression determined via immunohistochemistry and a decreased SMARCE1 transcript expression in the tumor cells. Analysis of time to progression or recurrence of patients within the clear cell meningioma group (n = 14) in comparison to those with meningioma WHO grade 2 (n = 220) revealed a similar outcome and support the assignment of WHO grade 2 to these tumors. Our findings indicate the existence of a highly distinct epigenetic signature of clear cell meningiomas, separate from all other variants of meningiomas, with recurrent mutations in the SMARCE1 gene. This suggests that these tumors may arise from a different precursor cell population than the broad spectrum of the other meningioma subtypes.
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http://dx.doi.org/10.1007/s00401-020-02247-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7847462PMC
February 2021

AN1-type zinc finger protein 3 (ZFAND3) is a transcriptional regulator that drives Glioblastoma invasion.

Nat Commun 2020 12 11;11(1):6366. Epub 2020 Dec 11.

NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg, Luxembourg.

The infiltrative nature of Glioblastoma (GBM), the most aggressive primary brain tumor, critically prevents complete surgical resection and masks tumor cells behind the blood brain barrier reducing the efficacy of systemic treatment. Here, we use a genome-wide interference screen to determine invasion-essential genes and identify the AN1/A20 zinc finger domain containing protein 3 (ZFAND3) as a crucial driver of GBM invasion. Using patient-derived cellular models, we show that loss of ZFAND3 hampers the invasive capacity of GBM, whereas ZFAND3 overexpression increases motility in cells that were initially not invasive. At the mechanistic level, we find that ZFAND3 activity requires nuclear localization and integral zinc-finger domains. Our findings indicate that ZFAND3 acts within a nuclear protein complex to activate gene transcription and regulates the promoter of invasion-related genes such as COL6A2, FN1, and NRCAM. Further investigation in ZFAND3 function in GBM and other invasive cancers is warranted.
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http://dx.doi.org/10.1038/s41467-020-20029-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7732990PMC
December 2020

Correction: Gold(I) complexes based on six-membered phosphorus heterocycles as bio-active molecules against brain cancer.

Chem Commun (Camb) 2020 Dec;56(95):15088

Division of Neurosurgical Research, Department of Neurosurgery, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany.

Correction for 'Gold(i) complexes based on six-membered phosphorus heterocycles as bio-active molecules against brain cancer' by Saskia Roesch et al., Chem. Commun., 2020, DOI: 10.1039/d0cc05761d.
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http://dx.doi.org/10.1039/d0cc90495cDOI Listing
December 2020

Integration and Comparison of Transcriptomic and Proteomic Data for Meningioma.

Cancers (Basel) 2020 Nov 5;12(11). Epub 2020 Nov 5.

Faculty of Medicine, School of Public Health, Imperial College London, Medical School, St Mary's Hospital, Praed Street, London W2 1NY, UK.

Meningioma are the most frequent primary intracranial tumour. Management of aggressive meningioma is complex, and development of effective biomarkers or pharmacological interventions is hampered by an incomplete knowledge of molecular landscape. Here, we present an integrated analysis of two complementary omics studies to investigate alterations in the "transcriptome-proteome" profile of high-grade (III) compared to low-grade (I) meningiomas. We identified 3598 common transcripts/proteins and revealed concordant up- and downregulation in grade III vs. grade I meningiomas. Concordantly upregulated genes included , a fatty acid binding protein and the monoamine oxidase , the latter of which we validated at the protein level and established an association with Food and Drug Administration (FDA)-approved drugs. Notably, we derived a plasma signature of 21 discordantly expressed genes showing positive changes in protein but negative in transcript levels of high-grade meningiomas, including the validated genes , , and , suggesting the acquisition of these proteins by tumour from plasma. Aggressive meningiomas were enriched in processes such as oxidative phosphorylation and RNA metabolism, whilst concordantly downregulated genes were related to reduced cellular adhesion. Overall, our study provides the first transcriptome-proteome characterisation of meningioma, identifying several novel and previously described transcripts/proteins with potential grade III biomarker and therapeutic significance.
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http://dx.doi.org/10.3390/cancers12113270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7694371PMC
November 2020

Gold(i) complexes based on six-membered phosphorus heterocycles as bio-active molecules against brain cancer.

Chem Commun (Camb) 2020 Dec 30;56(93):14593-14596. Epub 2020 Oct 30.

Division of Neurosurgical Research, Department of Neurosurgery, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 400, Heidelberg 69120, Germany.

π-Systems based on six-membered phosphorus heterocycles possess structural and electronic characteristics that clearly distinguish them from the rest of the organophosphorus molecules. However, their use in cancer therapy has been uninvestigated. In particular, glioblastoma is one of the most lethal brain tumors. The development of novel and more efficient drugs for the treatment of glioblastoma is thus crucial to battle this aggressive disease. Herein, we report a new family of gold(i) complexes based on six-membered phosphorus heterocycles as a promising tool to investigate brain cancer. We discovered that the latter complexes inhibit the proliferation, sensitize to apoptosis and hamper the migration of not only conventional but also stem-like glioblastoma cells. Our results unveil thus new research opportunities for the treatment of glioblastoma.
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http://dx.doi.org/10.1039/d0cc05761dDOI Listing
December 2020

Metabolic plasticity of IDH1 glioma cell lines is responsible for low sensitivity to glutaminase inhibition.

Cancer Metab 2020 21;8:23. Epub 2020 Oct 21.

Neuro-Oncology Branch, National Cancer Institute, Center for Cancer Research, National Institutes of Health, 37 Convent Drive, Building 37, Room 1136A, Bethesda, Maryland USA.

Background: Targeting glutamine metabolism in cancer has become an increasingly vibrant area of research. Mutant IDH1 (IDH1 ) gliomas are considered good candidates for targeting this pathway because of the contribution of glutamine to their newly acquired function: synthesis of 2-hydroxyglutarate (2HG).

Methods: We have employed a combination of C tracers including glutamine and glucose for investigating the metabolism of patient-derived IDH1 glioma cell lines through NMR and LC/MS. Additionally, genetic loss-of-function (in vitro and in vivo) approaches were performed to unravel the adaptability of these cell lines to the inhibition of glutaminase activity.

Results: We report the adaptability of IDH1 cells' metabolism to the inhibition of glutamine/glutamate pathway. The glutaminase inhibitor CB839 generated a decrease in the production of the downstream metabolites of glutamate, including those involved in the TCA cycle and 2HG. However, this effect on metabolism was not extended to viability; rather, our patient-derived IDH1 cell lines display a metabolic plasticity that allows them to overcome glutaminase inhibition.

Conclusions: Major metabolic adaptations involved pathways that can generate glutamate by using alternative substrates from glutamine, such as alanine or aspartate. Indeed, asparagine synthetase was upregulated both in vivo and in vitro revealing a new potential therapeutic target for a combinatory approach with CB839 against IDH1 gliomas.
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http://dx.doi.org/10.1186/s40170-020-00229-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579920PMC
October 2020

Increased Radiation-Associated T-Cell Infiltration in Recurrent IDH-Mutant Glioma.

Int J Mol Sci 2020 Oct 21;21(20). Epub 2020 Oct 21.

Division of Experimental Neurosurgery, Department of Neurosurgery, University Hospital of Heidelberg, 69120 Heidelberg, Germany.

Most gliomas are associated with a fatal prognosis and remain incurable because of their infiltrative growth. Consequently, the addition of immunotherapy to conventional therapy may improve patient outcomes. Here, we analyzed T-cell infiltration and, therefore, a major prerequisite for successful immunotherapy in a series of primary ( = 78) and recurrent ( = 66) isocitrate dehydrogenase (IDH)-mutant glioma and their changes following treatment with radio- and/or chemotherapy. After multicolor immunofluorescence staining, T cells were counted in entire tumor sections using a software-based setup. Newly diagnosed diffuse IDH-mutant gliomas displayed a median T-cell infiltration of 0.99 T cells/mm (range: 0-48.97 CD3 T cells/mm), which was about two-fold increased for CD3, helper, and cytotoxic T cells in recurrent glioma. Furthermore, T-cell infiltration of recurrent tumors was associated with the type of adjuvant treatment of the primary tumor. Interestingly, only glioma patients solely receiving radiotherapy presented consistently with increased T-cell infiltration in their recurrent tumors. This was confirmed in a subset of 27 matched pairs. In conclusion, differences in the T-cell infiltration of primary and recurrent gliomas were demonstrated, and evidence was provided for a beneficial long-term effect on T-cell infiltration upon treatment with radiotherapy.
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http://dx.doi.org/10.3390/ijms21207801DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7590222PMC
October 2020

Patient-derived organoids and orthotopic xenografts of primary and recurrent gliomas represent relevant patient avatars for precision oncology.

Acta Neuropathol 2020 12 3;140(6):919-949. Epub 2020 Oct 3.

Department of Neurosurgery, Henry Ford Health System, Detroit, MI, 48202, USA.

Patient-based cancer models are essential tools for studying tumor biology and for the assessment of drug responses in a translational context. We report the establishment a large cohort of unique organoids and patient-derived orthotopic xenografts (PDOX) of various glioma subtypes, including gliomas with mutations in IDH1, and paired longitudinal PDOX from primary and recurrent tumors of the same patient. We show that glioma PDOXs enable long-term propagation of patient tumors and represent clinically relevant patient avatars that retain histopathological, genetic, epigenetic, and transcriptomic features of parental tumors. We find no evidence of mouse-specific clonal evolution in glioma PDOXs. Our cohort captures individual molecular genotypes for precision medicine including mutations in IDH1, ATRX, TP53, MDM2/4, amplification of EGFR, PDGFRA, MET, CDK4/6, MDM2/4, and deletion of CDKN2A/B, PTCH, and PTEN. Matched longitudinal PDOX recapitulate the limited genetic evolution of gliomas observed in patients following treatment. At the histological level, we observe increased vascularization in the rat host as compared to mice. PDOX-derived standardized glioma organoids are amenable to high-throughput drug screens that can be validated in mice. We show clinically relevant responses to temozolomide (TMZ) and to targeted treatments, such as EGFR and CDK4/6 inhibitors in (epi)genetically defined subgroups, according to MGMT promoter and EGFR/CDK status, respectively. Dianhydrogalactitol (VAL-083), a promising bifunctional alkylating agent in the current clinical trial, displayed high therapeutic efficacy, and was able to overcome TMZ resistance in glioblastoma. Our work underscores the clinical relevance of glioma organoids and PDOX models for translational research and personalized treatment studies and represents a unique publicly available resource for precision oncology.
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http://dx.doi.org/10.1007/s00401-020-02226-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7666297PMC
December 2020

Temozolomide-Induced RNA Interactome Uncovers Novel LncRNA Regulatory Loops in Glioblastoma.

Cancers (Basel) 2020 Sep 10;12(9). Epub 2020 Sep 10.

NORLUX Neuro-Oncology Laboratory, Department of Oncology, Luxembourg Institute of Health, Luxembourg L-1526, Luxembourg.

Resistance to chemotherapy by temozolomide (TMZ) is a major cause of glioblastoma (GBM) recurrence. So far, attempts to characterize factors that contribute to TMZ sensitivity have largely focused on protein-coding genes, and failed to provide effective therapeutic targets. Long noncoding RNAs (lncRNAs) are essential regulators of epigenetic-driven cell diversification, yet, their contribution to the transcriptional response to drugs is less understood. Here, we performed RNA-seq and small RNA-seq to provide a comprehensive map of transcriptome regulation upon TMZ in patient-derived GBM stem-like cells displaying different drug sensitivity. In a search for regulatory mechanisms, we integrated thousands of molecular associations stored in public databases to generate a background "RNA interactome". Our systems-level analysis uncovered a coordinated program of TMZ response reflected by regulatory circuits that involve transcription factors, mRNAs, miRNAs, and lncRNAs. We discovered 22 lncRNAs involved in regulatory loops and/or with functional relevance in drug response and prognostic value in gliomas. Thus, the investigation of TMZ-induced gene networks highlights novel RNA-based predictors of chemosensitivity in GBM. The computational modeling used to identify regulatory circuits underlying drug response and prioritizing gene candidates for functional validation is applicable to other datasets.
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http://dx.doi.org/10.3390/cancers12092583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7563839PMC
September 2020

Nuclei Isolation from Fresh Frozen Brain Tumors for Single-Nucleus RNA-seq and ATAC-seq.

J Vis Exp 2020 08 25(162). Epub 2020 Aug 25.

Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg;

Adult diffuse gliomas exhibit inter- and intra-tumor heterogeneity. Until recently, the majority of large-scale molecular profiling efforts have focused on bulk approaches that led to the molecular classification of brain tumors. Over the last five years, single cell sequencing approaches have highlighted several important features of gliomas. The majority of these studies have utilized fresh brain tumor specimens to isolate single cells using flow cytometry or antibody-based separation methods. Moving forward, the use of fresh-frozen tissue samples from biobanks will provide greater flexibility to single cell applications. Furthermore, as the single-cell field advances, the next challenge will be to generate multi-omics data from either a single cell or the same sample preparation to better unravel tumor complexity. Therefore, simple and flexible protocols that allow data generation for various methods such as single-nucleus RNA sequencing (snRNA-seq) and single nucleus Assay for Transposase-Accessible Chromatin with high-throughput sequencing (snATAC-seq) will be important for the field. Recent advances in the single cell field coupled with accessible microfluidic instruments such as the 10x genomics platform have facilitated single cell applications in research laboratories. To study brain tumor heterogeneity, we developed an enhanced protocol for the isolation of single nuclei from fresh frozen gliomas. This protocol merges existing single cell protocols and combines a homogenization step followed by filtration and buffer mediated gradient centrifugation. The resulting samples are pure single nuclei suspensions that can be used to generate single nucleus gene expression and chromatin accessibility data from the same nuclei preparation.
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http://dx.doi.org/10.3791/61542DOI Listing
August 2020

TERT and DNMT1 expression predict sensitivity to decitabine in gliomas.

Neuro Oncol 2021 01;23(1):76-87

Neurology Clinic and National Center for Tumor Diseases, University Hospital Heidelberg, Heidelberg, Germany.

Background: Decitabine (DAC) is an FDA-approved DNA methyltransferase (DNMT) inhibitor that is used in the treatment of patients with myelodysplastic syndromes. Previously, we showed that DAC marks antitumor activity against gliomas with isocitrate dehydrogenase 1 (IDH1) mutations. Based on promising preclinical results, a clinical trial has been launched to determine the effect of DAC in IDH-mutant gliomas. The next step is to comprehensively assess the efficacy and potential determinants of response to DAC in malignant gliomas.

Methods: The expression and activity of telomerase reverse transcriptase (TERT) and DNMT1 were manipulated in patient-derived IDH1-mutant and -wildtype glioma lines, followed by assessment of cell proliferation with DAC treatment alone or in combination with telomerase inhibitors. RNA sequencing, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and correlation analysis were performed.

Results: IDH1-mutant glioma tumorspheres with hemizygous codeletion of chromosome arms 1p/19q were particularly sensitive to DAC and showed significant inhibition of DNA replication genes. Our transcriptome analysis revealed that DAC induced expression of cyclin-dependent kinase inhibitor 1A/p21 (CDKN1A), along with downregulation of TERT. These molecular changes were also observed following doxorubicin treatment, supporting the importance of DAC-induced DNA damage in contributing to this effect. We demonstrated that knockdown of p21 led to TERT upregulation. Strikingly, TERT overexpression increased DNMT1 levels and DAC sensitivity via a telomerase-independent mechanism. Furthermore, RNA inhibition (RNAi) targeting of DNMT1 abrogated DAC response in TERT-proficient glioma cells.

Conclusions: DAC downregulates TERT through p21 induction. Our data point to TERT and DNMT1 levels as potential determinants of response to DAC treatment.
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http://dx.doi.org/10.1093/neuonc/noaa207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7850113PMC
January 2021

Reduced chromatin binding of MYC is a key effect of HDAC inhibition in MYC amplified medulloblastoma.

Neuro Oncol 2021 02;23(2):226-239

Hopp Children's Cancer Center Heidelberg (KiTZ), Heidelberg, Germany.

Background: The sensitivity of myelocytomatosis oncogene (MYC) amplified medulloblastoma to class I histone deacetylase (HDAC) inhibition has been shown previously; however, understanding the underlying molecular mechanism is crucial for selection of effective HDAC inhibitors for clinical use. The aim of this study was to investigate the direct molecular interaction of MYC and class I HDAC2, and the impact of class I HDAC inhibition on MYC function.

Methods: Co-immunoprecipitation and mass spectrometry were used to determine the co-localization of MYC and HDAC2. Chromatin immunoprecipitation (ChIP) sequencing and gene expression profiling were used to analyze the co-localization of MYC and HDAC2 on DNA and the impact on transcriptional activity in primary tumors and a MYC amplified cell line treated with the class I HDAC inhibitor entinostat. The effect on MYC was investigated by quantitative real-time PCR, western blot, and immunofluorescence.

Results: HDAC2 is a cofactor of MYC in MYC amplified medulloblastoma. The MYC-HDAC2 complex is bound to genes defining the MYC-dependent transcriptional profile. Class I HDAC inhibition leads to stabilization and reduced DNA binding of MYC protein, inducing a downregulation of MYC activated genes (MAGs) and upregulation of MYC repressed genes (MRGs). MAGs and MRGs are characterized by opposing biological functions and by distinct enhancer-box distribution.

Conclusions: Our data elucidate the molecular interaction of MYC and HDAC2 and support a model in which inhibition of class I HDACs directly targets MYC's transactivating and transrepressing functions.
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http://dx.doi.org/10.1093/neuonc/noaa191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7906057PMC
February 2021

Infratentorial IDH-mutant astrocytoma is a distinct subtype.

Acta Neuropathol 2020 10 10;140(4):569-581. Epub 2020 Aug 10.

Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), German Consortium for Translational Cancer Research (DKTK), Heidelberg, Germany.

Diffuse IDH-mutant astrocytic tumors are rarely diagnosed in the cerebellum or brainstem. In this multi-institutional study, we characterized a series of primary infratentorial IDH-mutant astrocytic tumors with respect to clinical and molecular parameters. We report that about 80% of IDH mutations in these tumors are of non-IDH1-R132H variants which are rare in supratentorial astrocytomas. Most frequently, IDH1-R132C/G and IDH2-R172S/G mutations were present. Moreover, the frequencies of ATRX-loss and MGMT promoter methylation, which are typically associated with IDH mutations in supratentorial astrocytic tumors, were significantly lower in the infratentorial compartment. Gene panel sequencing revealed two samples with IDH1-R132C/H3F3A-K27M co-mutations. Genome-wide DNA methylation as well as chromosomal copy number profiling provided further evidence for a molecular distinctiveness of infratentorial IDH-mutant astrocytomas. Clinical outcome of patients with infratentorial IDH-mutant astrocytomas is significantly better than that of patients with diffuse midline gliomas, H3K27M-mutant (p < 0.005) and significantly worse than that of patients with supratentorial IDH-mutant astrocytomas (p = 0.028). The presented data highlight the very existence and distinctiveness of infratentorial IDH-mutant astrocytomas that have important implications for diagnostics and prognostication. They imply that molecular testing is critical for detection of these tumors, since many of these tumors cannot be identified by immunohistochemistry applied for the mutated IDH1-R132H protein or loss of ATRX.
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http://dx.doi.org/10.1007/s00401-020-02194-yDOI Listing
October 2020
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