bims-malgli Biomed News
on Biology of malignant gliomas
Issue of 2021‒01‒03
27 papers selected by
Oltea Sampetrean
Keio University

  1. Front Oncol. 2020 ;10 604121
      Malignant brain tumors remain uniformly fatal, even with the best-to-date treatment. For Glioblastoma (GBM), the most severe form of brain cancer in adults, the median overall survival is roughly over a year. New therapeutic options are urgently needed, yet recent clinical trials in the field have been largely disappointing. This is partially due to inappropriate preclinical model systems, which do not reflect the complexity of patient tumors. Furthermore, clinically relevant patient-derived models recapitulating the immune compartment are lacking, which represents a bottleneck for adequate immunotherapy testing. Emerging 3D organoid cultures offer innovative possibilities for cancer modeling. Here, we review available GBM organoid models amenable to a large variety of pre-clinical applications including functional bioassays such as proliferation and invasion, drug screening, and the generation of patient-derived orthotopic xenografts (PDOX) for validation of biological responses in vivo. We emphasize advantages and technical challenges in establishing immunocompetent ex vivo models based on co-cultures of GBM organoids and human immune cells. The latter can be isolated either from the tumor or from patient or donor blood as peripheral blood mononuclear cells (PBMCs). We also discuss the challenges to generate GBM PDOXs based on humanized mouse models to validate efficacy of immunotherapies in vivo. A detailed characterization of such models at the cellular and molecular level is needed to understand the potential and limitations for various immune activating strategies. Increasing the availability of immunocompetent GBM models will improve research on emerging immune therapeutic approaches against aggressive brain cancer.
    Keywords:  brain tumors; glioblastoma; glioma; immunotherapy; organoids; patient-derived xenografts; preclinical models; tumor microenvironment
  2. Cancers (Basel). 2020 Dec 21. pii: E3859. [Epub ahead of print]12(12):
      Glioblastoma (GBM) is a lethal disease with limited clinical treatment options available. Recently, a new inhibitor targeting the prominent cancer signaling pathway mTOR was discovered (Rapalink-1), but its therapeutic potential on stem cell populations of GBM is unknown. We applied a collection of physiological relevant organoid-like stem cell models of GBM and studied the effect of RL1 exposure on various cellular features as well as on the expression of mTOR signaling targets and stem cell molecules. We also undertook combination treatments with this agent and clinical GBM treatments tumor treating fields (TTFields) and the standard-of-care drug temozolomide, TMZ. Low nanomolar (nM) RL1 treatment significantly reduced cell growth, proliferation, migration, and clonogenic potential of our stem cell models. It acted synergistically to reduce cell growth when applied in combination with TMZ and TTFields. We performed an in silico analysis from the molecular data of diverse patient samples to probe for a relationship between the expression of mTOR genes, and mesenchymal markers in different GBM cohorts. We supported the in silico results with correlative protein data retrieved from tumor specimens. Our study further validates mTOR signaling as a druggable target in GBM and supports RL1, representing a promising therapeutic target in brain oncology.
    Keywords:  EMT; drug development; glioblastoma; human stem cell in vitro platform; mTOR; rapalink-1; risk assessment; therapy resistance; tumor treating fields
  3. Cancers (Basel). 2020 Dec 11. pii: E3720. [Epub ahead of print]12(12):
      The secondary structures of Scherer commonly known as perineuronal and perivascular satellitosis have been identified as a histopathological hallmark of diffuse, invasive, high-grade gliomas. They are recognised as perineuronal satellitosis when clusters of neoplastic glial cells surround neurons cell bodies and perivascular satellitosis when such tumour cells surround blood vessels infiltrating Virchow-Robin spaces. In this review, we provide an overview of emerging knowledge regarding how interactions between neurons and glioma cells can modulate tumour evolution and how neurons play a key role in glioma growth and progression, as well as the role of perivascular satellitosis into mechanisms of glioma cells spread. At the same time, we review the current knowledge about the role of perineuronal satellitosis and perivascular satellitosis within the tumour microenvironment (TME), in order to highlight critical knowledge gaps in research space.
    Keywords:  brain tumour; glioblastoma; invasion; perineuronal satellitosis; perivascular satellitosis; satellitosis; tumour heterogeneity
  4. Adv Mater. 2020 Dec 16. e2004776
      Glioblastoma (GBM) is the most prevalent and lethal adult primary central nervous system cancer. An immunosuppresive and highly heterogeneous tumor microenvironment, restricted delivery of chemotherapy or immunotherapy through the blood-brain barrier (BBB), together with the brain's unique biochemical and anatomical features result in its universal recurrence and poor prognosis. As conventional models fail to predict therapeutic efficacy in GBM, in vitro 3D models of GBM and BBB leveraging patient- or healthy-individual-derived cells and biomaterials through 3D bioprinting technologies potentially mimic essential physiological and pathological features of GBM and BBB. 3D-bioprinted constructs enable investigation of cellular and cell-extracellular matrix interactions in a species-matched, high-throughput, and reproducible manner, serving as screening or drug delivery platforms. Here, an overview of current 3D-bioprinted GBM and BBB models is provided, elaborating on the microenvironmental compositions of GBM and BBB, relevant biomaterials to mimic the native tissues, and bioprinting strategies to implement the model fabrication. Collectively, 3D-bioprinted GBM and BBB models are promising systems and biomimetic alternatives to traditional models for more reliable mechanistic studies and preclinical drug screenings that may eventually accelerate the drug development process for GBM.
    Keywords:  3D bioprinting; 3D models; biomaterials; blood-brain barrier; glioblastoma
  5. Cancers (Basel). 2020 Dec 22. pii: E9. [Epub ahead of print]13(1):
      The standard of care therapy of glioblastoma (GBM) includes invasive surgical resection, followed by radiotherapy and concomitant chemotherapy. However, this therapy has limited success, and the prognosis for GBM patients is very poor. Although many factors may contribute to the failure of current treatments, one of the main causes of GBM recurrences are glioma stem cells (GSCs). This review focuses on nanomedicine strategies that have been developed to eliminate GSCs and the benefits that they have brought to the fight against cancer. The first section describes the characteristics of GSCs and the chemotherapeutic strategies that have been used to selectively kill them. The second section outlines the nano-based delivery systems that have been developed to act against GSCs by dividing them into nontargeted and targeted nanocarriers. We also highlight the advantages of nanomedicine compared to conventional chemotherapy and examine the different targeting strategies that have been employed. The results achieved thus far are encouraging for the pursuit of effective strategies for the eradication of GSCs.
    Keywords:  brain tumor; cancer stem cell; glioblastoma; nanomedicine; targeted therapy
  6. Neuro Oncol. 2020 Dec 23. pii: noaa297. [Epub ahead of print]
      BACKGROUND: Glioblastoma is the most common and aggressive type of primary brain tumor, as most patients succumb to the disease less than two years after diagnosis. Critically, studies demonstrate that glioma recruits surrounding blood vessels, while some work suggests that tumor stem cells themselves directly differentiate into endothelial cells, yet the molecular and cellular dynamics of the endothelium in glioma are poorly characterized. The goal of this study was to establish molecular and morphological benchmarks for tumor associated vessels (TAVs) and tumor derived endothelial cells (TDECs) during GBM progression.METHODS: Using In-Utero Electroporation and CRISPR/Cas9 genome engineering to generate a native, immunocompetent mouse model of glioma, we characterized vascular-tumor dynamics in three dimensions during tumor progression. We employed bulk and single-cell RNA-Sequencing to elucidate the relationship between TAV and TDECs. We confirmed our findings in a patient derived orthotopic xenograft (PDOX) model.
    RESULTS: Using a mouse model of glioma, we identified progressive alteration of vessel function and morphogenesis over time. We also showed in our mouse model that TDECs are a rare subpopulation that contributes to vessels within the tumor, albeit to a limited degree. Furthermore, transcriptional profiling demonstrates that both TAVs and TDECs are molecularly distinct, and both populations feature extensive molecular heterogeneity. Finally, the distinct molecular signatures of these heterogenous populations are also present in human glioma.
    CONCLUSIONS: Our findings show extensive endothelial heterogeneity within the tumor and tumor microenvironment, and provide insights into the diverse cellular and molecular mechanisms that drive glioma vascularization and angiogenesis during tumorigenesis.
    Keywords:  Angiogenesis; Glioma; Lymphangiogenesis; Tumor Associated Vasculature (TAV); Tumor Derived Endothelial Cells (TDEC)
  7. Cancers (Basel). 2020 Dec 25. pii: E41. [Epub ahead of print]13(1):
      Glioblastoma (GBM) is a brain tumor characterized by poor therapeutic response and overall survival. Despite relevant progress in conventional treatments represented by the clinical use of temozolomide (TMZ), a combination of approaches might be a possible future direction for treating GBM. Transforming growth factor-beta-activated kinase-1 (TAK1) is an essential component in genotoxic stresses-induced NF-κB-activation and mitogen-activated protein kinase (MAPK)-pathways; however, the role of TAK1 in GBM-chemoresistance remains unknown. This study aimed to verify, in GBM human cell lines, in an in vivo U87-xenograft model and in TMZ-treated-patients, the effect of TAK1 inhibition on the sensitivity of GBM cells to chemotherapy. In vitro model, using GBM cell lines, showed that 5Z-7-oxozeaenol augmented the cytotoxic effects of TMZ, blocking TMZ-induced NF-κB-activation, reducing DNA-damage and enhancing TMZ-induced apoptosis in GMB cell lines. We showed a reduction in tumor burden as well as tumor volume in the xenograft model following the treatment with 5Z-7-oxozaenol associated with TMZ. Our results showed a significant up-regulation in TAK1, p-p38, p-JNK and NF-κB in glioblastoma TMZ-treated-patients and denoted the role of 5Z-7-oxozeaenol in increasing the sensitivity of GBM cells to chemotherapy, proving to be an effective coadjuvant to current GBM chemotherapeutic regimens, suggesting a new option for therapeutic treatment of GBM.
    Keywords:  TAK1; cell lines; glioblastoma; patients; temozolomide
  8. Cancers (Basel). 2020 Dec 11. pii: E3722. [Epub ahead of print]12(12):
      In contrast to most non-malignant tissue, cells comprising the brain tumour glioblastoma (GBM) preferentially utilise glycolysis for metabolism via "the Warburg effect". Research into therapeutics targeting the disease's highly glycolytic state offer a promising avenue to improve patient survival. These studies often employ GBM cell lines for in vitro studies which translate poorly to the in vivo patient context. The metabolic traits of five of the most used GBM cell lines were assessed and compared to primary GBM and matched, healthy brain tissue. In patient-derived GBM cell lines, the basal mitochondrial rate (p = 0.043) and ATP-linked respiration (p < 0.001) were lower than primary adjacent normal cells from the same patient, while reserve capacity (p = 0.037) and Krebs cycle capacity (p = 0.002) were higher. Three cell lines, U251MG, U373MG and D54, replicate the mitochondrial metabolism of primary GBM cells. Surprisingly, glycolytic capacity is not different between healthy and GBM tissue. The T98G cell line recapitulated glycolysis-related metabolic parameters of the primary GBM cells and is recommended for research relating to glycolysis. These findings can guide preclinical research into the development of novel therapeutics targeting metabolic pathways in GBM.
    Keywords:  cell culture; glioblastoma; glycolysis; metabolic flux; metabolism; oncology
  9. Pharmaceutics. 2020 Dec 10. pii: E1198. [Epub ahead of print]12(12):
      A paradigm shift in treating the most aggressive and malignant form of glioma is continuously evolving; however, these strategies do not provide a better life and survival index. Currently, neurosurgical debulking, radiotherapy, and chemotherapy are the treatment options available for glioma, but these are non-specific in action. Patients invariably develop resistance to these therapies, leading to recurrence and death. Receptor Tyrosine Kinases (RTKs) are among the most common cell surface proteins in glioma and play a significant role in malignant progression; thus, these are currently being explored as therapeutic targets. RTKs belong to the family of cell surface receptors that are activated by ligands which in turn activates two major downstream signaling pathways via Rapidly Accelerating Sarcoma/mitogen activated protein kinase/extracellular-signal-regulated kinase (Ras/MAPK/ERK) and phosphatidylinositol 3-kinase/a serine/threonine protein kinase/mammalian target of rapamycin (PI3K/AKT/mTOR). These pathways are critically involved in regulating cell proliferation, invasion, metabolism, autophagy, and apoptosis. Dysregulation in these pathways results in uncontrolled glioma cell proliferation, invasion, angiogenesis, and cancer progression. Thus, RTK pathways are considered a potential target in glioma management. This review summarizes the possible risk factors involved in the growth of glioblastoma (GBM). The role of RTKs inhibitors (TKIs) and the intracellular signaling pathways involved, small molecules under clinical trials, and the updates were discussed. We have also compiled information on the outcomes from the various endothelial growth factor receptor (EGFR)-TKIs-based nanoformulations from the preclinical and clinical points of view. Aided by an extensive literature search, we propose the challenges and potential opportunities for future research on EGFR-TKIs-based nanodelivery systems.
    Keywords:  epidermal growth factor receptor; glioblastoma; nanoformulations; receptor tyrosine kinases; small molecule inhibitors
  10. Neuro Oncol. 2020 Dec 24. pii: noaa277. [Epub ahead of print]
      Cancer immunotherapy has made remarkable advances with over fifty 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 in 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 and 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.
    Keywords:  clinical trial; conference report; glioblastoma; immunosuppression; immunotherapy
  11. Cancers (Basel). 2020 Dec 11. pii: E3724. [Epub ahead of print]12(12):
      In this review, we scrutinize the idea of using viral vectors either as cytotoxic agents or gene delivery tools for treatment of glioblastoma multiforme (GBM) in light of the experience that our laboratory has accumulated over ~20 years when using similar vectors in experimental neuroscience. We review molecular strategies and current clinical trials and argue that approaches which are based on targeting a specific biochemical pathway or a characteristic mutation are inherently prone to failure because of the high genomic instability and clonal selection characteristics of GBM. For the same reasons, attempts to develop a viral system which selectively transduces only GBM cells are also unlikely to be universally successful. One of the common gene therapy approaches is to use cytotoxic viruses which replicate and cause preferential lysis of the GBM cells. This strategy, in addition to its reliance on the specific biochemical makeup of the GBM cells, bears a risk of necrotic cell death accompanied by release of large quantities of pro-inflammatory molecules. On the other hand, engaging the immune system in the anti-GBM response seems to be a potential avenue to explore further. We suggest that a plausible strategy is to focus on viral vectors which efficiently transduce brain cells via a non-selective, ubiquitous mechanism and which target (ideally irreversibly) processes that are critical only for dividing tumor cells and are dispensable for quiescent brain cells.
    Keywords:  gene therapy; glioblastoma; glioma; viral vectors
  12. Int J Mol Sci. 2020 Dec 27. pii: E194. [Epub ahead of print]22(1):
      For decades, it has been known that the tumor microenvironment is significant for glioma progression, namely the infiltration of myeloid cells like microglia and macrophages. Hence, these cell types and their specific tasks in tumor progression are subject to ongoing research. However, the distribution of the brain resident microglia and the peripheral macrophages within the tumor tissue and their functional activity are highly debated. Results depend on the method used to discriminate between microglia and macrophages, whereby this specification is already difficult due to limited options to distinguish between these both cell populations that show mostly the same surface markers and morphology. Moreover, there are indications about various functions of microglia and macrophages but again varying on the method of discrimination. In our review, we summarize the current literature to determine which methods have been applied to differentiate the brain resident microglia from tumor-infiltrated macrophages. Furthermore, we compiled data about the proportion of microglia and macrophages in glioma tissues and ascertained if pro- or anti-tumoral effects could be allocated to one or the other myeloid cell population. Recent research made tremendous efforts to distinguish microglia from recruited macrophages. For future studies, it could be essential to verify which role these cells play in brain tumor pathology to proceed with novel immunotherapeutic strategies.
    Keywords:  glioma; myeloid cells; tumor microenvironment
  13. Cancers (Basel). 2020 Dec 23. pii: E19. [Epub ahead of print]13(1):
      Glioblastoma (GBM) is the most aggressive intrinsic brain tumor in adults. Despite maximal therapy consisting of surgery and radio/chemotherapy, GBM remains largely incurable with a median survival of less than 15 months. GBM has a strong immunosuppressive nature with a multitude of tumor and microenvironment (TME) derived factors that prohibit an effective immune response. To date, all clinical trials failed to provide lasting clinical efficacy, despite the relatively high success rates of preclinical studies to show effectivity of immunotherapy. Various factors may explain this discrepancy, including the inability of a single mouse model to fully recapitulate the complexity and heterogeneity of GBM. It is therefore critical to understand the features and limitations of each model, which should probably be combined to grab the full spectrum of the disease. In this review, we summarize the available knowledge concerning immune composition, stem cell characteristics and response to standard-of-care and immunotherapeutics for the most commonly available immunocompetent mouse models of GBM.
    Keywords:  animal model; glioblastoma; immune response; immunotherapy; model; murine; preclinical
  14. Cancers (Basel). 2020 Dec 18. pii: E3825. [Epub ahead of print]12(12):
      Despite pharmacological treatments and surgical practice options, the mortality rate of astrocytomas and glioblastomas remains high, thus representing a medical emergency for which it is necessary to find new therapeutic strategies. Fibroblast growth factors (FGFs) act through their associated receptors (FGFRs), a family of tyrosine kinase receptors consisting of four members (FGFR1-4), regulators of tissue development and repair. In particular, FGFRs play an important role in cell proliferation, survival, and migration, as well as angiogenesis, thus their gene alteration is certainly related to the development of the most common diseases, including cancer. FGFRs are subjected to multiple somatic aberrations such as chromosomal amplification of FGFR1; mutations and multiple dysregulations of FGFR2; and mutations, translocations, and significant amplifications of FGFR3 and FGFR4 that correlate to oncogenesis process. Therefore, the in-depth study of these receptor systems could help to understand the etiology of both astrocytoma and glioblastoma so as to achieve notable advances in more effective target therapies. Furthermore, the discovery of FGFR inhibitors revealed how these biological compounds improve the neoplastic condition by demonstrating efficacy and safety. On this basis, this review focuses on the role and involvement of FGFRs in brain tumors such as astrocytoma and glioblastoma.
    Keywords:  Fisogatinib; Futibatinib; astrocytoma; brain tumors; fibroblast growth factors (FGFs); fibroblast growth factors receptors (FGFRs); glioblastoma
  15. Semin Cancer Biol. 2020 Dec 25. pii: S1044-579X(20)30275-3. [Epub ahead of print]
      Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.
    Keywords:  Chromatin remodeling; DNA methylation; Epigenetics; Glioblastoma; Histone deacetylase inhibitors
  16. Cancer Discov. 2020 Dec 23. pii: CD-20-0219. [Epub ahead of print]
      Glioblastoma is a lethal brain tumor which exhibits heterogeneity and resistance to therapy. Our understanding of tumor homeostasis is limited by a lack of genetic tools to selectively identify tumor states and fate transitions. Here, we use glioblastoma subtype signatures to construct synthetic genetic tracing cassettes and investigate tumor heterogeneity at cellular and molecular level, in vitro and in vivo. Through synthetic locus control regions, we demonstrated that proneural glioblastoma is a hardwired identity, whereas the mesenchymal glioblastoma is an adaptive and metastable cell state driven by pro-inflammatory and differentiation cues and DNA damage, but not hypoxia. Importantly, we discovered that innate immune cells divert glioblastoma cells to a proneural-to-mesenchymal transition which confers therapeutic resistance. Our synthetic genetic tracing methodology is simple, scalable and widely applicable to study homeostasis in development and diseases. In glioblastoma, the method causally links distinct (micro)environmental, genetic and pharmacological perturbations and mesenchymal commitment.
  17. Cancers (Basel). 2020 Dec 26. pii: E47. [Epub ahead of print]13(1):
      Glioblastoma is the most frequent and aggressive form among malignant central nervous system primary tumors in adults. Standard treatment for newly diagnosed glioblastoma consists in maximal safe resection, if feasible, followed by radiochemotherapy and adjuvant chemotherapy with temozolomide; despite this multimodal treatment, virtually all glioblastomas relapse. Once tumors progress after first-line therapy, treatment options are limited and management of recurrent glioblastoma remains challenging. Loco-regional therapy with re-surgery or re-irradiation may be evaluated in selected cases, while traditional systemic therapy with nitrosoureas and temozolomide rechallenge showed limited efficacy. In recent years, new clinical trials using, for example, regorafenib or a combination of tyrosine kinase inhibitors and immunotherapy were performed with promising results. In particular, molecular targeted therapy could show efficacy in selected patients with specific gene mutations. Nonetheless, some molecular characteristics and genetic alterations could change during tumor progression, thus affecting the efficacy of precision medicine. We therefore reviewed the molecular and genomic landscape of recurrent glioblastoma, the strategy for clinical management and the major phase I-III clinical trials analyzing recent drugs and combination regimens in these patients.
    Keywords:  MGMT; glioblastoma; hypermutation; immunotherapy; new treatments; targeted therapy
  18. Cancers (Basel). 2020 Dec 23. pii: E30. [Epub ahead of print]13(1):
      The present investigation aimed to characterize the protein profile of cavitating ultrasound aspirator fluid of newly diagnosed and recurrent glioblastoma comparing diverse zones of collection, i.e., tumor core and tumor periphery, with the aid of 5-aminolevulinic acid fluorescence. The samples were pooled and analyzed in triplicate by LC-MS following the shotgun proteomic approach. The identified proteins were then grouped to disclose elements exclusive and common to the tumor state or tumor zones and submitted to gene ontology classification and pathway overrepresentation analysis. The proteins common to the distinct zones were further investigated by relative quantitation, following a label free approach, to disclose possible differences of expression. Nine proteins, i.e., tubulin 2B chain, CD59, far upstream element-binding, CD44, histone H1.4, caldesmon, osteopontin, tropomyosin chain and metallothionein-2, marked the core of newly diagnosed glioblastoma with respect to tumor periphery. Considering the tumor zone, including the core and the fluorescence positive periphery, the serine glycine biosynthesis, pentose phosphate, 5-hydroxytryptamine degredation, de novo purine biosynthesis and huntington disease pathways resulted statistically significantly overrepresented with respect to the human genome of reference. The fluorescence negative zone shared several protein elements with the tumor zone, possibly indicating the presence of pathological aspects of glioblastoma rather than of normal brain parenchyma. On the other hand, its exclusive protein elements were considered to represent the healthy zone and, accordingly, exhibiting no pathways overrepresentation. On the contrary to newly diagnosed glioblastoma, pathway overrepresentation was recognized only in the healthy zone of recurrent glioblastoma. The TGFβ signaling pathway, exclusively classified in the fluorescence negative periphery in newly diagnosed glioblastoma, was instead the exclusive pathway classified in the tumor core of recurrent glioblastoma. These results, preliminary obtained on sample pools, demonstrated the potential of cavitron ultrasonic sur.
    Keywords:  CUSA fluid; brain tumor; glioblastoma multiforme; proteomics
  19. STAR Protoc. 2020 Dec 18. 1(3): 100179
      Glioblastoma (GBM) remains the most common malignant primary brain tumor in adults with a median survival of less than ~15 months. Further understanding and therapeutic development rely on the use of clinically relevant models of GBM. Here, we present our patient-derived in vitro and in vivo models that enrich for GBM stem cells (GSCs), a subpopulation of tumor cells with stem cell-like properties that recapitulate the cellular heterogeneity of its parental tumor and resist conventional therapy and seed disease relapse. For complete details on the use and execution of this protocol, please refer to Vora et al. (2020).
    Keywords:  Cancer; Cell culture; Cell isolation; Model Organisms
  20. Neurooncol Adv. 2020 Jan-Dec;2(1):2(1): vdaa142
      Background: "Diffuse midline glioma (DMG), H3 K27M-mutant" is a new tumor entity established in the 2016 WHO classification of Tumors of the Central Nervous System that comprises a set of diffuse gliomas arising in midline structures and is molecularly defined by a K27M mutation in genes encoding the histone 3 variants H3.3 or H3.1. While this tumor entity is associated with poor prognosis in children, clinical experience in adults remains limited.Methods: Patient demographics, radiologic and pathologic characteristics, treatment course, progression, and patient survival were collected for 60 adult patients with DMG, H3 K27M-mutant. A subset of tumors also underwent next-generation sequencing. Analysis of progression-free survival and overall survival was conducted using Kaplan-Meier modeling, and univariate and multivariate analysis.
    Results: Median patient age was 32 years (range 18-71 years). Tumors were centered in the thalamus (n = 34), spinal cord (10), brainstem (5), cerebellum (4), or other midline sites (4), or were multifocal (3). Genomic profiling revealed p.K27M mutations exclusively in the H3F3A gene and an absence of mutations in HIST1H3B or HIST1H3C, which are present in approximately one-third of pediatric DMGs. Accompanying mutations in TP53, PPM1D, FGFR1, NF1, and ATRX were frequently found. The overall survival of this adult cohort was 27.6 months, longer than historical averages for both H3 K27M-mutant DMG in children and IDH-wildtype glioblastoma in adults.
    Conclusions: Together, these findings indicate that H3 K27M-mutant DMG represents a heterogeneous disease with regard to outcomes, sites of origin, and molecular pathogenesis in adults versus children.
    Keywords:  H3 K27M; adult; diffuse midline glioma; genetics; survival
  21. Front Bioeng Biotechnol. 2020 ;8 558375
      Gliomas are a dismal disease associated with poor survival and high morbidity. Current standard treatments have reached a therapeutic plateau even after combining maximal safe resection, radiation, and chemotherapy. In this setting, stem cells (SCs) have risen as a promising therapeutic armamentarium, given their intrinsic tumor homing as well as their natural or bioengineered antitumor properties. The interplay between stem cells and other therapeutic approaches such as nanoparticles holds the potential to synergize the advantages from the combined therapeutic strategies. Nanoparticles represent a broad spectrum of synthetic and natural biomaterials that have been proven effective in expanding diagnostic and therapeutic efforts, either used alone or in combination with immune, genetic, or cellular therapies. Stem cells have been bioengineered using these biomaterials to enhance their natural properties as well as to act as their vehicle when anticancer nanoparticles need to be delivered into the tumor microenvironment in a very precise manner. Here, we describe the recent developments of this new paradigm in the treatment of malignant gliomas.
    Keywords:  bioengineering; biomaterials; glioma; nanoparticles; nanotechnology; stem cells; surface functionalization; targeting
  22. Cancers (Basel). 2020 Dec 25. pii: E40. [Epub ahead of print]13(1):
      Recurrence of GBM is thought to be due to GBMSCs, which are particularly chemo-radioresistant and characterized by a high capacity to invade normal brain. Evidence is emerging that modulation of m6A RNA methylation plays an important role in tumor progression. However, the impact of this mRNA modification in GBM is poorly studied. We used patient-derived GBMSCs to demonstrate that high expression of the RNA demethylase, ALKBH5, increases radioresistance by regulating homologous recombination (HR). In cells downregulated for ALKBH5, we observed a decrease in GBMSC survival after irradiation likely due to a defect in DNA-damage repair. Indeed, we observed a decrease in the expression of several genes involved in the HR, including CHK1 and RAD51, as well as a persistence of γ-H2AX staining after IR. We also demonstrated in this study that ALKBH5 contributes to the aggressiveness of GBM by favoring the invasion of GBMSCs. Indeed, GBMSCs deficient for ALKBH5 exhibited a significant reduced invasion capability relative to control cells. Our data suggest that ALKBH5 is an attractive therapeutic target to overcome radioresistance and invasiveness of GBMSCs.
    Keywords:  ALKBH5; cancer stem cells; glioblastomas; radio-resistance; signaling
  23. STAR Protoc. 2020 Dec 18. 1(3): 100165
      Brainstem gliomas are aggressive tumors that are more prevalent in pediatric patients. The location of these tumors makes them inoperable, and currently there is no effective treatment. Recent genomic data revealed the unique biology of these tumors. The following protocol provides a method to incorporate these specific genetic lesions in a mouse glioma model. Using this model, the effects of these mutations in tumor progression and response to treatments can be studied within a relevant in vivo context. For complete details on the use and execution of this protocol, please refer to Mendez et al. (2020).
    Keywords:  Cancer; Cell Biology; Cell culture; Cell isolation; Neuroscience
  24. JCI Insight. 2020 Dec 22. pii: 130510. [Epub ahead of print]
      Asymmetric cell division (ACD) enables the maintenance of a stem cell population while simultaneously generating differentiated progeny. Cancer stem cells (CSCs) undergo multiple modes of cell division during tumor expansion and in response to therapy, yet the functional consequences of these division modes remain to be determined. Using a fluorescent reporter for cell surface receptor distribution during mitosis, we found that ACD generated a daughter cell with enhanced therapeutic resistance and increased co-enrichment of epidermal growth factor receptor (EGFR) and neurotrophin receptor (p75NTR) from a glioblastoma CSC. Stimulation of both receptors antagonized differentiation induction and promoted self-renewal capacity. p75NTR knockdown enhanced the therapeutic efficacy of EGFR inhibition, indicating that co-inheritance of p75NTR and EGFR promotes resistance to EGFR inhibition through a redundant mechanism. These data demonstrate that ACD produces progeny with co-enriched growth factor receptors, which contributes to the generation of a more therapeutically resistant CSC population.
    Keywords:  Brain cancer; Cancer; Cell Biology; Stem cells
  25. STAR Protoc. 2020 Dec 18. 1(3): 100174
      Glioblastoma (GBM) is the most common malignant adult brain tumor that is resistant to the standard care therapy. Advances in chimeric antigen receptor (CAR) T cell therapies have spurred renewed interest in developing CAR T cell therapies to target chemoradiotherapy-resistant brain tumor-initiating cells. This protocol shows how to isolate peripheral blood mononuclear cells from healthy donors and generate CAR T cells for the antigens of interest, and how to intracranially inject the CAR T cells into a patient-derived xenograft mouse model of GBM. For complete details on the use and execution of this protocol, please refer to Vora et al. (2020).
    Keywords:  Cancer; Immunology
  26. Neuro Oncol. 2020 Dec 30. pii: noaa306. [Epub ahead of print]
      For decades, cell biologists and cancer researchers have taken advantage of non-murine species to increase our understanding of the molecular processes that drive normal cell and tissue development, and when perturbed, cause cancer. The advent of whole genome sequencing has revealed the high genetic homology of these organisms to humans. Seminal studies in non-murine organisms such as D. melanogaster, C. elegans, and D. rerio identified many of the signaling pathways involved in cancer. Studies in these organisms offer distinct advantages over mammalian cell or murine systems. Compared to murine models, these three species have shorter lifespans, are less resource intense, and are amenable to high-throughput drug and RNA interference screening to test a myriad of promising drugs against novel targets. In this review, we introduce species specific breeding strategies, highlight the advantages of modeling brain tumours in each non-mammalian species, and underscore the successes attributed to scientific investigation using these models. We conclude with an optimistic proposal that discoveries in the fields of cancer research, and in particular neuro-oncology, may be expedited using these powerful screening tools and strategies.
    Keywords:   C. elegans ; Drosophila ; Worms; Zebrafish; brain tumour; high-throughput screening; signaling pathways
  27. Pharmaceutics. 2020 Dec 24. pii: E15. [Epub ahead of print]13(1):
      The presence of blood-brain barrier (BBB) and/or blood-brain-tumor barriers (BBTB) is one of the main obstacles to effectively deliver therapeutics to our central nervous system (CNS); hence, the outcomes following treatment of malignant brain tumors remain unsatisfactory. Although some approaches regarding BBB disruption or drug modifications have been explored, none of them reach the criteria of success. Convention-enhanced delivery (CED) directly infuses drugs to the brain tumor and surrounding tumor infiltrating area over a long period of time using special catheters. Focused ultrasound (FUS) now provides a non-invasive method to achieve this goal via combining with systemically circulating microbubbles to locally enhance the vascular permeability. In this review, different approaches of delivering therapeutic agents to the brain tumors will be discussed as well as the characterization of BBB and BBTB. We also highlight the mechanism of FUS-induced BBB modulation and the current progress of this technology in both pre-clinical and clinical studies.
    Keywords:  blood–brain barrier (BBB); blood–brain–tumor barrier (BBTB); central nervous system (CNS); convention-enhanced delivery (CED); focused ultrasound (FUS)