bims-malgli Biomed News
on Biology of malignant gliomas
Issue of 2022–08–21
seventeen papers selected by
Oltea Sampetrean, Keio University



  1. Front Immunol. 2022 ;13 964898
      Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults. Currently, the standard treatment of glioblastoma includes surgery, radiotherapy, and chemotherapy. Despite aggressive treatment, the median survival is only 15 months. GBM progression and therapeutic resistance are the results of the complex interactions between tumor cells and tumor microenvironment (TME). TME consists of several different cell types, such as stromal cells, endothelial cells and immune cells. Although GBM has the immunologically "cold" characteristic with very little lymphocyte infiltration, the TME of GBM can contain more than 30% of tumor-associated microglia and macrophages (TAMs). TAMs can release cytokines and growth factors to promote tumor proliferation, survival and metastasis progression as well as inhibit the function of immune cells. Thus, TAMs are logical therapeutic targets for GBM. In this review, we discussed the characteristics and functions of the TAMs and evaluated the state of the art of TAMs-targeting strategies in GBM. This review helps to understand how TAMs promote GBM progression and summarizes the present therapeutic interventions to target TAMs. It will possibly pave the way for new immune therapeutic avenues for GBM patients.
    Keywords:  glioblastoma; glioma; immunotherapy; macrophages; microglia; tumor-associated microglia/macrophages (TAMs)
    DOI:  https://doi.org/10.3389/fimmu.2022.964898
  2. Nat Commun. 2022 Aug 16. 13(1): 4814
      How the glioma immune microenvironment fosters tumorigenesis remains incompletely defined. Here, we use single-cell RNA-sequencing and multiplexed tissue-imaging to characterize the composition, spatial organization, and clinical significance of extracellular purinergic signaling in glioma. We show that microglia are the predominant source of CD39, while tumor cells principally express CD73. In glioblastoma, CD73 is associated with EGFR amplification, astrocyte-like differentiation, and increased adenosine, and is linked to hypoxia. Glioblastomas enriched for CD73 exhibit inflammatory microenvironments, suggesting that purinergic signaling regulates immune adaptation. Spatially-resolved single-cell analyses demonstrate a strong spatial correlation between tumor-CD73 and microglial-CD39, with proximity associated with poor outcomes. Similar spatial organization is present in pediatric high-grade gliomas including H3K27M-mutant diffuse midline glioma. These data reveal that purinergic signaling in gliomas is shaped by genotype, lineage, and functional state, and that core enzymes expressed by tumor and myeloid cells are organized to promote adenosine-rich microenvironments potentially amenable to therapeutic targeting.
    DOI:  https://doi.org/10.1038/s41467-022-32430-w
  3. Neuro Oncol. 2022 Aug 16. pii: noac197. [Epub ahead of print]
       BACKGROUND: IDH1/2 wildtype (IDHwt) glioma WHO grade 2 and 3 patients with pTERT mutation and/or EGFR amplification and/or +7/-10 chromosome gain/loss have a similar overall survival time as IDHwt glioblastoma patients, and are both considered glioblastoma IDHwt according to the WHO 2021 classification. However, differences in seizure onset have been observed. This study aimed to compare the course of epilepsy in the two glioblastoma subtypes.
    METHODS: We analyzed epilepsy data of an existing cohort including IDHwt histologically lower-grade glioma WHO grade 2 and 3 with molecular glioblastoma-like profile (IDHwt hLGG) and IDHwt glioblastoma patients. Primary outcome was the incidence proportion of epilepsy during the disease course. Secondary outcomes included, among others, onset of epilepsy, number of seizure days and antiepileptic drug (AED) polytherapy.
    RESULTS: Out of 254 patients, 78% (50/64) IDHwt hLGG and 68% (129/190) IDHwt glioblastoma patients developed epilepsy during the disease (p=0.121). Epilepsy onset before histopathological diagnosis occurred more frequently in IDHwt hLGG compared to IDHwt glioblastoma patients (90% versus 60%, p<0.001), with a significantly longer median time to diagnosis (3.5 versus 1.3 months, p<0.001). Median total seizure days was also longer for IDHwt hLGG patients (7.0 versus 3.0, p=0.005), and they received more often AED polytherapy (32% versus 17%, p=0.028).
    CONCLUSIONS: Although the incidence proportion of epilepsy during the entire disease course is similar, IDHwt hLGG patients show a significantly higher incidence of epilepsy before diagnosis and a significantly longer median time between first seizure and diagnosis compared to IDHwt glioblastoma patients, indicating a distinct clinical course.
    Keywords:  Glioma; IDHwt; epilepsy; glioblastoma; seizure
    DOI:  https://doi.org/10.1093/neuonc/noac197
  4. Nat Commun. 2022 Aug 15. 13(1): 4767
      Pediatric and adult high-grade gliomas are the most common primary malignant brain tumors, with poor prognosis due to recurrence and tumor infiltration after therapy. Quiescent cells have been implicated in tumor recurrence and treatment resistance, but their direct visualization and targeting remain challenging, precluding their mechanistic study. Here, we identify a population of malignant cells expressing Prominin-1 in a non-proliferating state in pediatric high-grade glioma patients. Using a genetic tool to visualize and ablate quiescent cells in mouse brain cancer and human cancer organoids, we reveal their localization at both the core and the edge of the tumors, and we demonstrate that quiescent cells are involved in infiltration of brain cancer cells. Finally, we find that Harmine, a DYRK1A/B inhibitor, partially decreases the number of quiescent and infiltrating cancer cells. Our data point to a subpopulation of quiescent cells as partially responsible of tumor invasiveness, one of the major causes of brain cancer morbidity.
    DOI:  https://doi.org/10.1038/s41467-022-32448-0
  5. Cancer Res. 2022 Aug 16. pii: CAN-22-0101. [Epub ahead of print]
      Early detection of tumor cell death in glioblastoma following treatment with chemoradiation has the potential to distinguish between true disease progression and pseudoprogression. Tumor cell death can be detected non-invasively in vivo by imaging the production of [2,3-2H2]malate from [2,3-2H2]fumarate using 2H magnetic resonance (MR) spectroscopic imaging. We show here that 2H MR spectroscopy and spectroscopic imaging measurements of [2,3-2H2]fumarate metabolism can detect tumor cell death in orthotopically implanted glioblastoma models within 48 hours following the completion of chemoradiation. Following the injection of [2,3-2H2]fumarate into tumor-bearing mice, production of [2,3-2H2]malate was measured in a human cell line-derived model and in radio-sensitive and radio-resistant patient-derived models of glioblastoma that were treated with temozolomide followed by targeted fractionated irradiation. The increase in the [2,3-2H2]malate/[2,3-2H2]fumarate signal ratio post-treatment, which correlated with histological assessment of cell death, was a more sensitive indicator of treatment response than diffusion-weighted and contrast agent-enhanced 1H MRI measurements, which have been used clinically to detect responses of glioblastoma to chemoradiation. Overall, early detection of glioblastoma cell death using 2H MRI of malate production from fumarate could help improve the clinical evaluation of response to chemoradiation.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-22-0101
  6. Neurooncol Adv. 2022 Jan-Dec;4(1):4(1): vdac089
       Background: Glioblastoma (GBM) has poor prognosis despite aggressive treatment. Dendritic cell (DC) vaccines are promising, but widespread clinical use has not been achieved, possibly reflecting manufacturing issues of antigen choice and DC potency. We previously optimized vaccine manufacture utilizing allogeneic human GBM tumor cell lysate and potent, mature autologous DCs. Here, we report a phase I study using this optimized DC vaccine in combination with standard therapy.
    Methods: Following surgical resection and radiation with concurrent temozolomide (TMZ), newly diagnosed adult GBM patients received intradermal DC vaccines plus TMZ. Primary endpoints were safety and feasibility. Immune and treatment responses were recorded.
    Results: Twenty-one patients were enrolled in this study. One progressed between leukapheresis and vaccine manufacture. Twenty patients received treatment per protocol. Vaccine doses (≥15) were generated following a single leukapheresis for each patient. No dose-limiting vaccine toxicities were encountered. One patient had symptomatic, histologically proven pseudoprogression. Median progression-free survival was 9.7 months. Median overall survival was 19 months. Overall survival was 25% at 2 years and 10% at 4 years. One patient remains progression-free 5 years after enrollment. Specific CD8 T-cell responses for the tumor-associated antigen gp100 were seen post-vaccination. Patients entered the trial with a leukocyte deficit compared to healthy donors which partly normalized over the course of therapy.
    Conclusions: This vaccine platform is safe and highly feasible in combination with standard therapy for newly diagnosed patients. Imaging, histological, survival, and immunological data suggest a positive biological response to therapy that warrants further investigation.
    Keywords:  dendritic cell vaccine; glioblastoma; immunotherapy; temozolomide
    DOI:  https://doi.org/10.1093/noajnl/vdac089
  7. Acta Neuropathol Commun. 2022 Aug 17. 10(1): 115
      Chromosomal instability (CIN) is a fundamental property of cancer and a key underlying mechanism of tumorigenesis and malignant progression, and has been documented in a wide variety of cancers, including colorectal carcinoma with mutations in genes such as APC. Recent reports have demonstrated that CIN, driven in part by mutations in genes maintaining overall genomic stability, is found in subsets of adult-type diffusely infiltrating gliomas of all histologic and molecular grades, with resulting elevated overall copy number burden, chromothripsis, and poor clinical outcome. Still, relatively few studies have examined the effect of this process, due in part to the difficulty of routinely measuring CIN clinically. Herein, we review the underlying mechanisms of CIN, the relationship between chromosomal instability and malignancy, the prognostic significance and treatment potential in various cancers, systemic disease, and more specifically, in diffusely infiltrating glioma subtypes. While still in the early stages of discovery compared to other solid tumor types in which CIN is a known driver of malignancy, the presence of CIN as an early factor in gliomas may in part explain the ability of these tumors to develop resistance to standard therapy, while also providing a potential molecular target for future therapies.
    Keywords:  Astrocytoma; CIN; Chromosomal instability; Chromothripsis; Copy number burden; Copy number variation; Glioblastoma; Glioma; Oligodendroglioma
    DOI:  https://doi.org/10.1186/s40478-022-01420-w
  8. Proc Natl Acad Sci U S A. 2022 Aug 23. 119(34): e2206208119
      Although glioblastoma multiforme (GBM) is not an invariably cold tumor, checkpoint inhibition has largely failed in GBM. In order to investigate T cell-intrinsic properties that contribute to the resistance of GBM to endogenous or therapeutically enhanced adaptive immune responses, we sorted CD4+ and CD8+ T cells from the peripheral blood, normal-appearing brain tissue, and tumor bed of nine treatment-naive patients with GBM. Bulk RNA sequencing of highly pure T cell populations from these different compartments was used to obtain deep transcriptomes of tumor-infiltrating T cells (TILs). While the transcriptome of CD8+ TILs suggested that they were partly locked in a dysfunctional state, CD4+ TILs showed a robust commitment to the type 17 T helper cell (TH17) lineage, which was corroborated by flow cytometry in four additional GBM cases. Therefore, our study illustrates that the brain tumor environment in GBM might instruct TH17 commitment of infiltrating T helper cells. Whether these properties of CD4+ TILs facilitate a tumor-promoting milieu and thus could be a target for adjuvant anti-TH17 cell interventions needs to be further investigated.
    Keywords:  RNA sequencing; TH17 cells; gene set enrichment analysis; glioblastoma multiforme; tissue residency
    DOI:  https://doi.org/10.1073/pnas.2206208119
  9. Neuro Oncol. 2022 Aug 17. pii: noac205. [Epub ahead of print]
      Isocitrate dehydrogenase (IDH) 1 or 2 mutations confer a favorable prognosis compared to IDH-wildtype in astrocytoma, frequently denoting a lower grade malignancy. However, recent molecular profiling has identified specific aggressive tumor subgroups with clear clinical prognostic implications that are independent of histologic grading. The homozygous deletion of CDKN2A/B is the strongest implicated independent indicator of poor prognosis within IDH-mutant astrocytoma, and the identification of this alteration in these lower histologic grade tumors transforms their biology toward an aggressive grade 4 phenotype clinically. CDKN2A/B homozygous deletion is now sufficient to define a grade 4 tumor in IDH-mutant astrocytomas regardless of histologic appearance, yet there are currently no effective molecularly informed targeted therapies for these tumors. The biologic impact of CDKN2A/B homozygous deletion in IDH-mutant tumors and the optimal treatment strategy for this molecular subgroup remains insufficiently explored. Here we review the current understanding of the translational significance of homozygous deletion of CDKN2A/B gene expression in IDH-mutant astrocytoma and associated diagnostic and therapeutic implications.
    Keywords:  CDKN2A/B; IDH mutant astrocytoma; grade 4 glioma
    DOI:  https://doi.org/10.1093/neuonc/noac205
  10. Nat Commun. 2022 Aug 15. 13(1): 4795
      Glioblastoma (GBM) is a highly aggressive primary brain tumour and is resistant to nearly all available treatments, including natural killer (NK) cell immunotherapy. However, the factors mediating NK cell evasion in GBM remain largely unclear. Here, we report that EZH2-92aa, a protein encoded by circular EZH2, is overexpressed in GBM and induces the immune evasion of GBM stem cells (GSCs) from NK cells. Positively regulated by DEAD-box helicase 3 (DDX3), EZH2-92aa directly binds the major histocompatibility complex class I polypeptide-related sequence A/B (MICA/B) promoters and represses their transcription; it also indirectly represses UL16-binding protein (ULBP) transcription by stabilizing EZH2. The downregulation of NK group 2D ligands (NKG2DLs, including MICA/B and ULBPs) in GSCs mediates NK cell resistance. Moreover, stable EZH2-92aa knockdown enhances NK cell-mediated GSC eradication in vitro and in vivo and synergizes with anti-PD1 therapy. Our results highlight the immunosuppressive function of EZH2-92aa in inhibiting the NK cell response in GBM and the clinical potential of targeting EZH2-92aa for NK-cell-directed immune therapy.
    DOI:  https://doi.org/10.1038/s41467-022-32311-2
  11. Cancer Cell. 2022 Aug 12. pii: S1535-6108(22)00324-5. [Epub ahead of print]
      Mutations affecting isocitrate dehydrogenase (IDH) enzymes are prevalent in glioma, leukemia, and other cancers. Although mutant IDH inhibitors are effective against leukemia, they seem to be less active in aggressive glioma, underscoring the need for alternative treatment strategies. Through a chemical synthetic lethality screen, we discovered that IDH1-mutant glioma cells are hypersensitive to drugs targeting enzymes in the de novo pyrimidine nucleotide synthesis pathway, including dihydroorotate dehydrogenase (DHODH). We developed a genetically engineered mouse model of mutant IDH1-driven astrocytoma and used it and multiple patient-derived models to show that the brain-penetrant DHODH inhibitor BAY 2402234 displays monotherapy efficacy against IDH-mutant gliomas. Mechanistically, this reflects an obligate dependence of glioma cells on the de novo pyrimidine synthesis pathway and mutant IDH's ability to sensitize to DNA damage upon nucleotide pool imbalance. Our work outlines a tumor-selective, biomarker-guided therapeutic strategy that is poised for clinical translation.
    Keywords:  DHODH; IDH; cancer metabolism; genetically engineered mouse model; glioma; isocitrate dehydrogenase; pyrimidine nucleotides
    DOI:  https://doi.org/10.1016/j.ccell.2022.07.011
  12. Cancer Cell. 2022 Aug 15. pii: S1535-6108(22)00325-7. [Epub ahead of print]
      Diffuse midline glioma (DMG) is a uniformly fatal pediatric cancer driven by oncohistones that do not readily lend themselves to drug development. To identify druggable targets for DMG, we conducted a genome-wide CRISPR screen that reveals a DMG selective dependency on the de novo pathway for pyrimidine biosynthesis. This metabolic vulnerability reflects an elevated rate of uridine/uracil degradation that depletes DMG cells of substrates for the alternate salvage pyrimidine biosynthesis pathway. A clinical stage inhibitor of DHODH (rate-limiting enzyme in the de novo pathway) diminishes uridine-5'-phosphate (UMP) pools, generates DNA damage, and induces apoptosis through suppression of replication forks-an "on-target" effect, as shown by uridine rescue. Matrix-assisted laser desorption/ionization (MALDI) mass spectroscopy imaging demonstrates that this DHODH inhibitor (BAY2402234) accumulates in the brain at therapeutically relevant concentrations, suppresses de novo pyrimidine biosynthesis in vivo, and prolongs survival of mice bearing intracranial DMG xenografts, highlighting BAY2402234 as a promising therapy against DMGs.
    Keywords:  ATR; BAY2402234; DHODH; DPYD; de novo pyrimidine synthesis; diffuse intrinsic pontine glioma; diffuse midline glioma; elimusertib; pyrimidine degradation; replication stress
    DOI:  https://doi.org/10.1016/j.ccell.2022.07.012
  13. Autophagy. 2022 Aug 18.
      Aberrant growth factor receptor signaling is among the most common oncogenic drivers in cancer biology. Receptor signaling classically induces cancer growth through signaling cascades that mediate effects largely through transcriptional control. Recently, post-transcriptional RNA modifications, collectively designated as epitranscriptomics, have emerged as a critical layer of dysregulation in cancer biology. We recently reported that PDGFR (platelet derived growth factor receptor) activity in cancer stem cells (CSCs) derived from glioblastoma patients display increased post-transcriptional mRNA methylation (N6-methyladenosine [m6A]), which promotes CSC maintenance through regulation of mitophagy. Specifically, PDGF-PDGFRB signaling upregulates expression of the m6A methyltransferase METTL3, which then decorates the mitophagy regulator OPTN (optineurin) mRNA with m6A, thereby promoting OPTN mRNA degradation. Glioblastomas express lower levels of OPTN than normal brain, and forced expression of OPTN reduces tumor growth, supporting a tumor suppressive role for OPTN. Pharmacological targeting of METTL3 with PDGFR or activation of mitophagy demonstrate a combinatorial benefit. Collectively, our results suggest that upstream regulation of mitophagy in lethal cancers is mediated through growth factor receptor control of post-transcriptional RNA regulation, offering novel therapeutic paradigms.
    Keywords:  Cancer stem cell; METTL3; N6-methyladenosine (m6A); OPTN; PDGF; PDGFR; glioblastoma; mitophagy; optineurin
    DOI:  https://doi.org/10.1080/15548627.2022.2114765
  14. Sci Rep. 2022 Aug 13. 12(1): 13796
      Therapeutic resistance to kinase inhibitors constitutes a major unresolved clinical challenge in cancer and especially in glioblastoma. Multi-kinase inhibitors may be used for simultaneous targeting of multiple target kinases and thereby potentially overcome kinase inhibitor resistance. However, in most cases the identification of the target kinases mediating therapeutic effects of multi-kinase inhibitors has been challenging. To tackle this important problem, we developed an actionable targets of multi-kinase inhibitors (AToMI) strategy and used it for characterization of glioblastoma target kinases of staurosporine derivatives displaying synergy with protein phosphatase 2A (PP2A) reactivation. AToMI consists of interchangeable modules combining drug-kinase interaction assay, siRNA high-throughput screening, bioinformatics analysis, and validation screening with more selective target kinase inhibitors. As a result, AToMI analysis revealed AKT and mitochondrial pyruvate dehydrogenase kinase PDK1 and PDK4 as kinase targets of staurosporine derivatives UCN-01, CEP-701, and K252a that synergized with PP2A activation across heterogeneous glioblastoma cells. Based on these proof-of-principle results, we propose that the application and further development of AToMI for clinically applicable multi-kinase inhibitors could provide significant benefits in overcoming the challenge of lack of knowledge of the target specificity of multi-kinase inhibitors.
    DOI:  https://doi.org/10.1038/s41598-022-18118-7
  15. Acta Neuropathol Commun. 2022 Aug 19. 10(1): 120
      A major obstacle to identifying improved treatments for pediatric low-grade brain tumors (gliomas) is the inability to reproducibly generate human xenografts. To surmount this barrier, we leveraged human induced pluripotent stem cell (hiPSC) engineering to generate low-grade gliomas (LGGs) harboring the two most common pediatric pilocytic astrocytoma-associated molecular alterations, NF1 loss and KIAA1549:BRAF fusion. Herein, we identified that hiPSC-derived neuroglial progenitor populations (neural progenitors, glial restricted progenitors and oligodendrocyte progenitors), but not terminally differentiated astrocytes, give rise to tumors retaining LGG histologic features for at least 6 months in vivo. Additionally, we demonstrated that hiPSC-LGG xenograft formation requires the absence of CD4 T cell-mediated induction of astrocytic Cxcl10 expression. Genetic Cxcl10 ablation is both necessary and sufficient for human LGG xenograft development, which additionally enables the successful long-term growth of patient-derived pediatric LGGs in vivo. Lastly, MEK inhibitor (PD0325901) treatment increased hiPSC-LGG cell apoptosis and reduced proliferation both in vitro and in vivo. Collectively, this study establishes a tractable experimental humanized platform to elucidate the pathogenesis of and potential therapeutic opportunities for childhood brain tumors.
    Keywords:  BRAF; Human induced pluripotent stem cells; Low-grade glioma; NF1; Pediatric brain tumor; Pilocytic astrocytoma
    DOI:  https://doi.org/10.1186/s40478-022-01428-2