bims-malgli Biomed News
on Biology of malignant gliomas
Issue of 2021‒12‒26
sixteen papers selected by
Oltea Sampetrean
Keio University

  1. Antioxidants (Basel). 2021 Dec 14. pii: 1988. [Epub ahead of print]10(12):
      Glioblastoma remains the deadliest form of brain cancer, largely because these tumors become resistant to standard of care treatment with radiation and chemotherapy. Intracellular production of reactive oxygen species (ROS) is necessary for chemo- and radiotherapy-induced cytotoxicity. Here, we assessed whether antioxidant catalase (CAT) affects glioma cell sensitivity to temozolomide and radiation. Using The Cancer Genome Atlas database, we found that CAT mRNA expression is upregulated in glioma tumor tissue compared with non-tumor tissue, and the level of expression negatively correlates with the overall survival of patients with high-grade glioma. In U251 glioma cells, CAT overexpression substantially decreased the basal level of hydrogen peroxide, enhanced anchorage-independent cell growth, and facilitated resistance to the chemotherapeutic drug temozolomide and ionizing radiation. Importantly, pharmacological inhibition of CAT activity reduced the proliferation of glioma cells isolated from patient biopsy samples. Moreover, U251 cells overexpressing CAT formed neurospheres in neurobasal medium, whereas control cells did not, suggesting that the radio- and chemoresistance conferred by CAT may be due in part to the enrichment of glioma stem cell populations. Finally, CAT overexpression significantly decreased survival in an orthotopic mouse model of glioma. These results demonstrate that CAT regulates chemo- and radioresistance in human glioma.
    Keywords:  catalase; glioblastoma multiforme; hydrogen peroxide; radiation; reactive oxygen species (ROS); temozolomide
  2. Cancers (Basel). 2021 Dec 07. pii: 6160. [Epub ahead of print]13(24):
      Glioblastoma is the most aggressive brain tumor in adults. Multiple lines of evidence suggest that microglia create a microenvironment favoring glioma invasion and proliferation. Our previous studies and literature reports indicated the involvement of focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2) in glioma cell proliferation and invasion, stimulated by tumor-infiltrating microglia. However, the specific microglia-released factors that modulate Pyk2 and FAK signaling in glioma cells are unknown. In this study, 20 human glioblastoma specimens were evaluated with the use of RT-PCR and western blotting. A Pierson correlation test demonstrated a correlation (0.6-1.0) between the gene expression levels for platelet-derived growth factor β(PDGFβ), stromal-derived factor 1α (SDF-1α), IL-6, IL-8, and epidermal growth factor (EGF) in tumor-purified microglia and levels of p-Pyk2 (Y579/Y580) and p-FAK(Y925) in glioma cells. siRNA knockdown against Pyk2 or FAK in three primary glioblastoma cell lines, developed from the investigated specimens, in combination with the cytokine receptor inhibitors gefitinib (1 μM), DMPQ (200 nM), and burixafor (1 μM) identified EGF, PDGFβ, and SDF-1α as key extracellular factors in the Pyk2- and FAK-dependent activation of invadopodia formation and the migration of glioma cells. EGF and IL-6 were identified as regulators of the Pyk2- and FAK-dependent activation of cell viability and mitosis.
    Keywords:  FAK; Pyk2; cell signaling; cytokines; glioblastoma; invasion; microglia; primary human cell lines; proliferation; tumor microenvironment
  3. Biomolecules. 2021 Dec 13. pii: 1870. [Epub ahead of print]11(12):
      Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with an extremely poor prognosis. There is a dire need to develop effective therapeutics to overcome the intrinsic and acquired resistance of GBM to current therapies. The process of developing novel anti-neoplastic drugs from bench to bedside can incur significant time and cost implications. Drug repurposing may help overcome that obstacle. A wide range of drugs that are already approved for clinical use for the treatment of other diseases have been found to target GBM-associated signaling pathways and are being repurposed for the treatment of GBM. While many of these drugs are undergoing pre-clinical testing, others are in the clinical trial phase. Since GBM stem cells (GSCs) have been found to be a main source of tumor recurrence after surgery, recent studies have also investigated whether repurposed drugs that target these pathways can be used to counteract tumor recurrence. While several repurposed drugs have shown significant efficacy against GBM cell lines, the blood-brain barrier (BBB) can limit the ability of many of these drugs to reach intratumoral therapeutic concentrations. Localized intracranial delivery may help to achieve therapeutic drug concentration at the site of tumor resection while simultaneously minimizing toxicity and side effects. These strategies can be considered while repurposing drugs for GBM.
    Keywords:  brain tumor; drug delivery; glioma; repurposed drugs
  4. Front Oncol. 2021 ;11 718590
      Glioblastoma (GBM) is an aggressive and fatal malignancy that despite decades of trials has limited therapeutic options. Antibody drug conjugates (ADCs) are composed of a monoclonal antibody which specifically recognizes a cellular surface antigen linked to a cytotoxic payload. ADCs have demonstrated superior efficacy and/or reduced toxicity in a range of haematological and solid tumors resulting in nine ADCs receiving regulatory approval. ADCs have also been explored in patients with brain tumours but with limited success to date. While earlier generations ADCs in glioma patients have had limited success and high toxicity, newer and improved ADCs characterised by low immunogenicity and more effective payloads have shown promise in a range of tumour types. These newer ADCs have also been tested in glioma patients, however, with mixed results. Factors affecting the effectiveness of ADCs to target the CNS include the blood brain barrier which acts as a physical and biochemical barrier, the pro-cancerogenic and immunosuppressive tumor microenvironment and tumour characteristics like tumour volume and antigen expression. In this paper we review the data regarding the ongoing the development of ADCs in glioma patients as well as potential strategies to overcome these barriers to maximise their therapeutic potential.
    Keywords:  antibody drug conjugates (ADC); biomarkers; blood brain barrier; glioblastoma; glioma; molecular imaging; tumour microenvironment
  5. Neuro Oncol. 2021 Dec 21. pii: noab269. [Epub ahead of print]
      Phenotypic plasticity has emerged as a major contributor to intra-tumoral heterogeneity and treatment resistance in cancer. Increasing evidence shows that glioblastoma (GBM) cells display prominent intrinsic plasticity and reversibly adapt to dynamic microenvironmental conditions. Limited genetic evolution at recurrence further suggests that resistance mechanisms also largely operate at the phenotypic level. Here we review recent literature underpinning the role of GBM plasticity in creating gradients of heterogeneous cells including those that carry cancer stem cell (CSC) properties. A historical perspective from the hierarchical to the nonhierarchical concept of CSCs towards the recent appreciation of GBM plasticity is provided. Cellular states interact dynamically with each other and with the surrounding brain to shape a flexible tumor ecosystem, which enables swift adaptation to external pressure including treatment. We present the key components regulating intra-tumoral phenotypic heterogeneity and the equilibrium of phenotypic states, including genetic, epigenetic, and microenvironmental factors. We further discuss plasticity in the context of intrinsic tumor resistance, where a variable balance between preexisting resistant cells and adaptive persisters leads to reversible adaptation upon treatment. Innovative efforts targeting regulators of plasticity and mechanisms of state transitions towards treatment-resistant states are needed to restrict the adaptive capacities of GBM.
    Keywords:  glioblastoma; plasticity; treatment resistance; tumor heterogeneity; tumor microenvironment
  6. Int J Mol Sci. 2021 Dec 13. pii: 13382. [Epub ahead of print]22(24):
      Glioblastomas (GBMs) are complex ecosystems composed of highly multifaceted tumor and myeloid cells capable of responding to different environmental pressures, including therapies. Recent studies have uncovered the diverse phenotypical identities of brain-populating myeloid cells. Differences in the immune proportions and phenotypes within tumors seem to be dictated by molecular features of glioma cells. Furthermore, increasing evidence underscores the significance of interactions between myeloid cells and glioma cells that allow them to evolve in a synergistic fashion to sustain tumor growth. In this review, we revisit the current understanding of glioma-infiltrating myeloid cells and their dialogue with tumor cells in consideration of their increasing recognition in response and resistance to immunotherapies as well as the immune impact of the current chemoradiotherapy used to treat gliomas.
    Keywords:  gliomas; immunotherapy; macrophages; microglia
  7. JCI Insight. 2021 Dec 23. pii: e153526. [Epub ahead of print]
      The discovery of the oncometabolite 2-hydroxyglutarate in isocitrate dehydrogenase (IDH)1-mutated tumor entities affirmed the role of metabolism in cancer. Yet, large databases with tissue metabolites that are modulated by IDH1 mutation remain an area of development. Here, we present an unprecedented and valuable resource for tissue metabolites in diffuse glioma and their modulations by IDH1 mutation, histology and tumor treatments in 101 tissue samples from 73 diffuse glioma patients (24 astrocytoma, 17 oligodendroglioma, 32 glioblastoma), investigated by NMR-based metabolomics and supported by RNA sequencing. We discovered comparison-specific metabolites and pathways modulated by IDH1 ("IDH1 mutation status cohort") and tumor entity. The "Longitudinal investigation cohort" provides metabolic profiles of untreated and corresponding treated glioma samples at first progression. Most interestingly, univariate and multivariate cox regressions and Kaplan Meier analyses revealed that tissue metabolites correlate with progression-free and overall survival. Thus, this study introduces novel candidate prognostic and surrogate metabolite biomarkers for future prospective clinical studies aiming at further refining patient stratification in diffuse glioma. Furthermore, our data will facilitate the generation of so far unanticipated hypotheses for experimental studies to advance our molecular understanding of glioma biology.
    Keywords:  Brain cancer; Oncology
  8. Cancers (Basel). 2021 Dec 07. pii: 6169. [Epub ahead of print]13(24):
      Glioblastoma multiforme (GBM) is a deadly brain tumor with a large unmet therapeutic need. Here, we tested the hypothesis that wild-type p53 is a negative transcriptional regulator of SLC7A11, the gene encoding the System xc- (SXC) catalytic subunit, xCT, in GBM. We demonstrate that xCT expression is inversely correlated with p53 expression in patient tissue. Using representative patient derived (PDX) tumor xenolines with wild-type, null, and mutant p53 we show that p53 expression negatively correlates with xCT expression. Using chromatin immunoprecipitation studies, we present a molecular interaction whereby p53 binds to the SLC7A11 promoter, suppressing gene expression in PDX GBM cells. Accordingly, genetic knockdown of p53 increases SLC7A11 transcript levels; conversely, over-expressing p53 in p53-null GBM cells downregulates xCT expression and glutamate release. Proof of principal studies in mice with flank gliomas demonstrate that daily treatment with the mutant p53 reactivator, PRIMA-1Met, results in reduced tumor growth associated with reduced xCT expression. These findings suggest that p53 is a molecular switch for GBM glutamate biology, with potential therapeutic utility.
    Keywords:  SLC7A11; glioblastoma multiforme; glutamate; p53
  9. Front Oncol. 2021 ;11 783067
      Glioblastoma represents the most devastating form of human brain cancer, associated with a very poor survival rate of patients. Unfortunately, treatment options are currently limited and the gold standard pharmacological treatment with the chemotherapeutic drug temozolomide only slightly increases the survival rate. Experimental studies have shown that the efficiency of temozolomide can be improved by inducing ferroptosis - a recently discovered form of cell death, which is different from apoptosis, necrosis, or necroptosis and, which is characterized by lipid peroxidation and reactive oxygen species accumulation. Ferroptosis can also be activated to improve treatment of malignant stages of neuroblastoma, meningioma, and glioma. Due to their role in cancer treatment, ferroptosis-gene signatures have recently been evaluated for their ability to predict survival of patients. Despite positive effects during chemotherapy, the drugs used to induce ferroptosis - such as erastin and sorafenib - as well as genetic manipulation of key players in ferroptosis - such as the cystine-glutamate exchanger xCT and the glutathione peroxidase GPx4 - also impact neuronal function and cognitive capabilities. In this review, we give an update on ferroptosis in different brain tumors and summarize the impact of ferroptosis on healthy tissues.
    Keywords:  brain tumor therapy; erastin; ferroptosis; glioblastoma; neuroblastoma; neuron; off-target effects; xCT
  10. Cells. 2021 Dec 02. pii: 3400. [Epub ahead of print]10(12):
      Li Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome caused by germline mutations in TP53. TP53 is the most common mutated gene in human cancer, occurring in 30-50% of glioblastomas (GBM). Here, we highlight a precision medicine platform to identify potential targets for a GBM patient with LFS. We used a comparative transcriptomics approach to identify genes that are uniquely overexpressed in the LFS GBM patient relative to a cancer compendium of 12,747 tumor RNA sequencing data sets, including 200 GBMs. STAT1 and STAT2 were identified as being significantly overexpressed in the LFS patient, indicating ruxolitinib, a Janus kinase 1 and 2 inhibitors, as a potential therapy. The LFS patient had the highest level of STAT1 and STAT2 expression in an institutional high-grade glioma cohort of 45 patients, further supporting the cancer compendium results. To empirically validate the comparative transcriptomics pipeline, we used a combination of adherent and organoid cell culture techniques, including ex vivo patient-derived organoids (PDOs) from four patient-derived cell lines, including the LFS patient. STAT1 and STAT2 expression levels in the four patient-derived cells correlated with levels identified in the respective parent tumors. In both adherent and organoid cultures, cells from the LFS patient were among the most sensitive to ruxolitinib compared to patient-derived cells with lower STAT1 and STAT2 expression levels. A spheroid-based drug screening assay (3D-PREDICT) was performed and used to identify further therapeutic targets. Two targeted therapies were selected for the patient of interest and resulted in radiographic disease stability. This manuscript supports the use of comparative transcriptomics to identify personalized therapeutic targets in a functional precision medicine platform for malignant brain tumors.
    Keywords:  Li Fraumeni; glioblastoma; organoid; precision medicine; transcriptomics
  11. Cancers (Basel). 2021 Dec 16. pii: 6320. [Epub ahead of print]13(24):
      Tumor tropic neural stem cells (NSCs) can improve the anti-tumor efficacy of oncovirotherapy agents by protecting them from rapid clearance by the immune system and delivering them to multiple distant tumor sites. We recently completed a first-in-human trial assessing the safety of a single intracerebral dose of NSC-delivered CRAd-Survivin-pk7 (NSC.CRAd-S-pk7) combined with radiation and chemotherapy in newly diagnosed high-grade glioma patients. The maximum feasible dose was determined to be 150 million NSC.CRAd-Sp-k7 (1.875 × 1011 viral particles). Higher doses were not assessed due to volume limitations for intracerebral administration and the inability to further concentrate the study agent. It is possible that therapeutic efficacy could be maximized by administering even higher doses. Here, we report IND-enabling studies in which an improvement in treatment efficacy is achieved in immunocompetent mice by administering multiple treatment cycles intracerebrally. The results imply that pre-existing immunity does not preclude therapeutic benefits attainable by administering multiple rounds of an oncolytic adenovirus directly into the brain.
    Keywords:  glioma; immunotherapy; neural stem cell; oncolytic virus; stem cell carrier; viral delivery
  12. FEBS Open Bio. 2021 Dec 19.
      One of the major challenges in cancer research is finding models that closely resemble tumors within patients. Human tissue slice cultures are a promising approach to provide a model of the patient's tumor biology ex vivo. Recently, it was shown that these slices can be successfully analyzed by whole transcriptome sequencing as well as automated histochemistry, increasing their usability as preclinical model. Glioblastoma multiforme (GBM) is a highly malignant brain tumor with poor prognosis and little is known about its genetic background and heterogeneity regarding therapy success. In this study, tissue from the tumors of 25 patients with primary GBM were processed into slice cultures and treated with standard therapy (irradiation and temozolomide). Total RNA sequencing and automated histochemistry were performed to enable analysis of treatment effects at a transcriptional and histological level. Slice cultures from long-term survivors (overall survival (OS) > 24 months) exhibited more apoptosis than cultures from patients with shorter OS. Proliferation within these slices was slightly increased in contrast to other groups, but not significantly. Among all samples, 58 protein-coding genes were upregulated and 32 downregulated in treated vs. untreated slice cultures. In general, an upregulation of DNA damage-related and cell cycle checkpoint genes as well as enrichment of genotoxicity pathways and p53-dependent signaling was found after treatment. Overall, the current study reproduces knowledge from former studies regarding the feasibility of transcriptomic analyses and automated histology in tissue slice cultures. We further demonstrate that the experimental data merge with the clinical follow up of the patients, which improves the applicability of our model system.
    Keywords:  Glioblastoma multiforme; RNA sequencing; radiochemotherapy; tissue slice cultures
  13. Neuro Oncol. 2021 Dec 24. pii: noab292. [Epub ahead of print]
      BACKGROUND: ATRX inactivation occurs with IDH1 R132H and p53 mutations in over 80% of Grade II/III astrocytomas. It is believed that ATRX loss contributes to oncogenesis by dysregulating epigenetic and telomere mechanisms but effects on anti-glioma immunity have not been explored. This paper examines how ATRX loss contributes to the malignant and immunosuppressive phenotypes of IDH1 R132H/p53mut glioma cells and xenografts.METHODS: Isogenic astrocytoma cells (+/-IDH1 R132H/+/-ATRXloss) were established in p53mut astrocytoma cell lines using lentivirus encoding doxycycline inducible IDH1 R132H, ATRX shRNA or Lenti-CRISPR/Cas9 ATRX. Effects of IDH1 R132H+/- ATRXloss on cell migration, growth, DNA repair and tumorigenicity were evaluated by clonal growth, transwell and scratch assays, MTT, immunofluorence and immunoblotting assays and xenograft growth. Effects on the expression and function of modulators of the immune microenvironment were quantified by qRT-PCR, immunoblot, T-cell function, macrophage polarization and flow cytometry assays. Pharmacologic inhibitors were used to examine epigenetic drivers of the immunosuppressive transcriptome of IDH1 R132H/p53mut/ATRXloss cells.
    RESULTS: Adding ATRX loss to the IDH1 R132H/p53mut background promoted astrocytoma cell aggressiveness, induced expression of BET proteins BRD3/4 and an immune suppressive transcriptome consisting of up-regulated immune checkpoints (e.g. PD-L1, PD-L2) and altered cytokine/chemokine profiles (e.g. IL33, CXCL8, CSF2, IL6, CXCL9). ATRX loss enhanced the capacity of IDH1 R132H/p53mut cells to induce T-cell apoptosis, tumorigenic/anti-inflammatory macrophage polarization and Treg infiltration. The transcriptional and biological immune suppressive responses to ATRX loss were enhanced by temozolomide and radiation and abrogated by pharmacologic BET inhibition.
    CONCLUSIONS: ATRX loss activates a BRD-dependent immune suppressive transcriptome and immune escape mechanism in IDH1 R132H/p53mut astrocytoma cells.
    Keywords:  ATRX loss; BRD-dependent-immune suppressive transcriptome; IDH1 mutant astrocytoma; glioma immune microenvironment
  14. Acta Neuropathol Commun. 2021 Dec 24. 9(1): 200
      Giant cell glioblastoma (GC-GBM) is a rare variant of IDH-wt GBM histologically characterized by the presence of numerous multinucleated giant cells and molecularly considered a hybrid between IDH-wt and IDH-mutant GBM. The lack of an objective definition, specifying the percentage of giant cells required for this diagnosis, may account for the absence of a definite molecular profile of this variant. This study aimed to clarify the molecular landscape of GC-GBM, exploring the mutations and copy number variations of 458 cancer-related genes, tumor mutational burden (TMB), and microsatellite instability (MSI) in 39 GBMs dichotomized into having 30-49% (15 cases) or ≥ 50% (24 cases) GCs. The type and prevalence of the genetic alterations in this series was not associated with the GCs content (< 50% or ≥ 50%). Most cases (82% and 51.2%) had impairment in TP53/MDM2 and PTEN/PI3K pathways, but a high proportion also featured TERT promoter mutations (61.5%) and RB1 (25.6%) or NF1 (25.6%) alterations. EGFR amplification was detected in 18% cases in association with a shorter overall survival (P = 0.004). Sixteen (41%) cases had a TMB > 10 mut/Mb, including two (5%) that harbored MSI and one with a POLE mutation. The frequency of RB1 and NF1 alterations and TMB counts were significantly higher compared to 567 IDH wild type (P < 0.0001; P = 0.0003; P < 0.0001) and 26 IDH-mutant (P < 0.0001; P = 0.0227; P < 0.0001) GBMs in the TCGA PanCancer Atlas cohort. These findings demonstrate that the molecular landscape of GBMs with at least 30% giant cells is dominated by the impairment of TP53/MDM2 and PTEN/PI3K pathways, and additionally characterized by frequent RB1 alterations and hypermutation and by EGFR amplification in more aggressive cases. The high frequency of hypermutated cases suggests that GC-GBMs might be candidates for immune check-point inhibitors clinical trials.
    Keywords:  Giant cell; Glioblastoma; Mismatch repair; RB1; Tumor mutational burden
  15. Commun Biol. 2021 Dec 21. 4(1): 1420
      Elevated aldehyde dehydrogenase (ALDH) activity correlates with poor outcome for many solid tumors as ALDHs may regulate cell proliferation and chemoresistance of cancer stem cells (CSCs). Accordingly, potent, and selective inhibitors of key ALDH enzymes may represent a novel CSC-directed treatment paradigm for ALDH+ cancer types. Of the many ALDH isoforms, we and others have implicated the elevated expression of ALDH1A3 in mesenchymal glioma stem cells (MES GSCs) as a target for the development of novel therapeutics. To this end, our structure of human ALDH1A3 combined with in silico modeling identifies a selective, active-site inhibitor of ALDH1A3. The lead compound, MCI-INI-3, is a selective competitive inhibitor of human ALDH1A3 and shows poor inhibitory effect on the structurally related isoform ALDH1A1. Mass spectrometry-based cellular thermal shift analysis reveals that ALDH1A3 is the primary binding protein for MCI-INI-3 in MES GSC lysates. The inhibitory effect of MCI-INI-3 on retinoic acid biosynthesis is comparable with that of ALDH1A3 knockout, suggesting that effective inhibition of ALDH1A3 is achieved with MCI-INI-3. Further development is warranted to characterize the role of ALDH1A3 and retinoic acid biosynthesis in glioma stem cell growth and differentiation.
  16. Brain Sci. 2021 Dec 18. pii: 1655. [Epub ahead of print]11(12):
      Gliomas represent 70% of all central system nervous tumors and are classified according to the degree of malignancy as low- or high-grade. The permanent activation of the EGFR/PI3K/AKT pathway by various genetic or post-translational alterations of EGFR, PI3KCA, and PTEN has been associated with increased proliferation and resistance to apoptosis. The present study aimed to analyze the molecular/genetic changes in the EGFR/PI3K/AKT/PTEN pathway between low-grade and high-grade gliomas in a sample of Colombian patients. A total of 30 samples were tested for PI3K and PTEN mutations, EGFR, PI3K, and AKT gene amplification, AKT, PI3K, BAX, Bcl2 expression levels, and phosphorylation of AKT and PTEN, EGFR and/or PI3K gene amplification was found in 50% of low-grade and 45% of high-grade ones. AKT amplification was found in 25% of the low-grade and 13.6% of the high-grade. The expression of PI3K, AKT, Bcl2, and BAX was increased particularly to a high degree. AKT phosphorylation was found in 66% of low-grade and 31.8% of high-grade. Increased phosphorylation of PTEN was found in 77% low-grade and 66% high-grade. Our results indicate that alterations in the EGFR/PI3K/AKT/PTEN pathway could be important in the initiation and malignant progression of this type of tumor.
    Keywords:  apoptosis; cancer; gliomas; pathway; proliferation