bims-malgli Biomed News
on Biology of malignant gliomas
Issue of 2020‒11‒15
thirteen papers selected by
Oltea Sampetrean
Keio University

  1. Cancers (Basel). 2020 Nov 07. pii: E3297. [Epub ahead of print]12(11):
    Maas SLN, van Solinge TS, Schnoor R, Yekula A, Senders JT, de Vrij J, Robe P, Carter BS, Balaj L, Arkesteijn GJA, Nolte-'t Hoen ENM, Broekman MLD.
      Background: In glioblastoma (GB), tissue is required for accurate diagnosis and subtyping. Tissue can be obtained through resection or (stereotactic) biopsy, but these invasive procedures provide risks for patients. Extracellular vesicles (EVs) are small, cell-derived vesicles that contain miRNAs, proteins, and lipids, and possible candidates for liquid biopsies. GB-derived EVs can be found in the blood of patients, but it is difficult to distinguish them from circulating non-tumor EVs. 5-aminolevulinic acid (5-ALA) is orally administered to GB patients to facilitate tumor visualization and maximal resection, as it is metabolized to fluorescent protoporphyrin IX (PpIX) that accumulates in glioma cells. In this study, we assessed whether PpIX accumulates in GB-derived EVs and whether these EVs could be isolated and characterized to enable a liquid biopsy in GB. Methods: EVs were isolated from the conditioned media of U87 cells treated with 5-ALA by differential ultracentrifugation. Blood samples were collected and processed from healthy controls and patients undergoing 5-ALA guided surgery for GB. High-resolution flow cytometry (hFC) enabled detection and sorting of PpIX-positive EVs, which were subsequently analyzed by digital droplet PCR (ddPCR). Results: PpIX-positive EVs could be detected in conditioned cell culture media as well as in patient samples after administration of 5-ALA. By using hFC, we could sort the PpIX-positive EVs for further analysis with ddPCR, which indicated the presence of EVs and GB-associated miRNAs. Conclusion: GB-derived EVs can be isolated from the plasma of GB patients by using 5-ALA induced fluorescence. Although many challenges remain, our findings show new possibilities for the development of blood-based liquid biopsies in GB patients.
    Keywords:  5 aminolevulinic acid; extracellular vesicles; glioblastoma; high-resolution flow cytometry; protoporphyrin IX
  2. Clin Cancer Res. 2020 Nov 10. pii: clincanres.0018.2020. [Epub ahead of print]
    Vigneswaran K, Boyd NH, Oh SY, Lallani S, Boucher A, Neill SG, Olson JJ, Read RD.
      PURPOSE: Glioblastoma (GBM), neoplasms derived from glia and neuro-glial progenitor cells, are the most common and lethal malignant primary brain tumors diagnosed in adults, with a median survival of 14 months. GBM tumorigenicity is often driven by genetic aberrations in receptor tyrosine kinases (RTKs), such as amplification and mutation of EGFR.EXPERIMENTAL DESIGN: Using a Drosophila glioma model and human patient-derived GBM stem cells and xenograft models, we genetically and pharmacologically tested whether the YAP and TAZ transcription co-activators, effectors of the Hippo pathway that promote gene expression via TEAD co-factors, are key drivers of GBM tumorigenicity downstream of oncogenic EGFR signaling.
    RESULTS: YAP and TAZ are highly expressed in EGFR-amplified/mutant human GBMs, and their knockdown in EGFR-amplified/mutant GBM cells inhibited proliferation and elicited apoptosis. Our results indicate that YAP/TAZ-TEAD directly regulate transcription of SOX2, C-MYC, and EGFR itself to create a feedforward loop to drive survival and proliferation of human GBM cells. Moreover, the benzoporphyrin derivative verteporfin, a disruptor of YAP/TAZ-TEAD mediated transcription, preferentially induced apoptosis of cultured patient-derived EGFR-amplified/mutant GBM cells, suppressed expression of YAP/TAZ transcriptional targets, including EGFR, and conferred significant survival benefit in an orthotopic xenograft GBM model. Our efforts led us to design and initiate a phase 0 clinical trial of Visudyne, an FDA-approved liposomal formulation of verteporfin, where we used intraoperative fluorescence to observe verteporfin uptake into tumor cells in GBM tumors in human patients.
    CONCLUSIONS: Together, our data suggest that verteporfin is a promising therapeutic agent for EGFR amplified and mutant GBM.
  3. Nat Commun. 2020 11 10. 11(1): 5687
    Gregory JV, Kadiyala P, Doherty R, Cadena M, Habeel S, Ruoslahti E, Lowenstein PR, Castro MG, Lahann J.
      Glioblastoma (GBM), the most aggressive form of brain cancer, has witnessed very little clinical progress over the last decades, in part, due to the absence of effective drug delivery strategies. Intravenous injection is the least invasive drug delivery route to the brain, but has been severely limited by the blood-brain barrier (BBB). Inspired by the capacity of natural proteins and viral particulates to cross the BBB, we engineered a synthetic protein nanoparticle (SPNP) based on polymerized human serum albumin (HSA) equipped with the cell-penetrating peptide iRGD. SPNPs containing siRNA against Signal Transducer and Activation of Transcription 3 factor (STAT3i) result in in vitro and in vivo downregulation of STAT3, a central hub associated with GBM progression. When combined with the standard of care, ionized radiation, STAT3i SPNPs result in tumor regression and long-term survival in 87.5% of GBM-bearing mice and prime the immune system to develop anti-GBM immunological memory.
  4. Neuro Oncol. 2020 Nov 11. pii: noaa259. [Epub ahead of print]
    Mitchell K, Troike K, Silver DJ, Lathia JD.
      Cellular heterogeneity is a hallmark of advanced cancers and has been ascribed to a population of self-renewing, therapeutically resistant cancer stem cells (CSCs). Glioblastoma (GBM), the most common primary malignant brain tumor, has been a paradigm for the study of CSCs and has helped to define key aspects of the disease as well as served as the basis for the development of next-generation therapies. While there continues to be an expansion in our knowledge of how CSCs contribute to GBM progression, opportunities have emerged to revisit this conceptual framework. In this review, we will summarize the current state of CSCs in GBM using key concepts of evolution as a paradigm (variation, inheritance, selection, and time) to describe how the CSC state is subject to alterations of cell intrinsic and extrinsic interactions that shape their evolutionarily trajectory. We identify emerging areas for future consideration, including moving beyond a single CSC population to appreciate CSCs as a cell state that is subject to plasticity, as opposed to a discrete population. These future considerations will not only have an impact on our understanding of this ever-expanding field but will also provide an opportunity to inform future therapies to effectively target this complex and devastating disease.
    Keywords:  cancer stem cell; glioblastoma; review; stem cell state
  5. Cancers (Basel). 2020 Nov 09. pii: E3303. [Epub ahead of print]12(11):
    Andreatta F, Beccaceci G, Fortuna N, Celotti M, De Felice D, Lorenzoni M, Foletto V, Genovesi S, Rubert J, Alaimo A.
      Glioblastoma (GB) is the most frequent and aggressive type of glioma. The lack of reliable GB models, together with its considerable clinical heterogeneity, has impaired a comprehensive investigation of the mechanisms that lead to tumorigenesis, cancer progression, and response to treatments. Recently, 3D cultures have opened the possibility to overcome these challenges and cerebral organoids are emerging as a leading-edge tool in GB research. The opportunity to easily engineer brain organoids via gene editing and to perform co-cultures with patient-derived tumor spheroids has enabled the analysis of cancer development in a context that better mimics brain tissue architecture. Moreover, the establishment of biobanks from GB patient-derived organoids represents a crucial starting point to improve precision medicine therapies. This review exemplifies relevant aspects of 3D models of glioblastoma, with a specific focus on organoids and their involvement in basic and translational research.
    Keywords:  glioblastoma; organoids; precision medicine; preclinical cancer models; stem cells; translational research; tumoroids
  6. Sci Rep. 2020 Nov 11. 10(1): 19542
    Landry AP, Balas M, Alli S, Spears J, Zador Z.
      Tumor-associated macrophages (TAMs) constitute up to 50% of tumor bulk in glioblastoma (GBM) and play an important role in tumor maintenance and progression. The recently discovered differences between invading tumour periphery and hypoxic tumor core implies that macrophage biology is also distinct by location. This may provide further insight into the observed treatment resistance to immune modulation. We hypothesize that macrophage activation occurs through processes that are distinct in tumor periphery versus core. We therefore investigated regional differences in TAM recruitment and evolution in GBM by combining open source single cell and bulk gene expression data. We used single cell gene expression data from 4 glioblastomas (total of 3589 cells) and 122 total bulk samples obtained from 10 different patients. Cell identity, ontogeny (bone-marrow derived macrophages-BMDM vs microglia), and macrophage activation state were inferred using verified gene expression signatures. We captured the spectrum of immune states using cell trajectory analysis with pseudotime ordering. In keeping with previous studies, TAMs carrying BMDM identity were more abundant in tumor bulk while microglia-derived TAMs dominated the tumor periphery across all macrophage activation states including pre-activation. We note that core TAMs evolve towards a pro-inflammatory state and identify a subpopulation of cells based on a gene program exhibiting strong, opposing correlation with Programmed cell Death-1 (PD-1) signaling, which may correlate to their response to PD-1 inhibition. By contrast, peripheral TAMs evolve towards anti-inflammatory phenotype and contains a population of cells strongly associated with NFkB signaling. Our preliminary analysis suggests important regional differences in TAMs with regard to recruitment and evolution. We identify regionally distinct and potentially actionable cell subpopulations and advocate the need for a multi-targeted approach to GBM therapeutics.
  7. Am J Cancer Res. 2020 ;10(10): 3475-3486
    Kim JY, Jo Y, Oh HK, Kim EH.
      A newly diagnosed or recurrent Glioblastoma multiforme (GBM) can be treated with Tumor-treating fields (TTFields), an emerging type of alternative electric field-based therapy using low-intensity electric fields. TTFields have a penchant to arrest mitosis, eventually leading to apoptosis. Therefore, it is regarded as a potential anticancer therapy. However, in this study, we confirmed the combined efficacy of sorafenib and TTFields to improve the treatment efficiency of malignant GBM. Experimentation revealed the ability of sorafenib to decrease the signal transducer and activator of transcription 3 (STAT3) and this inhibition increased the sensitivity of TTFields in preventing tumor expansion. It was found that both combinatorial as well as monotherapy aimed to inhibit or reduce the level of STAT3, but the extent was different and based upon the reaction conditions. This drug is also capable of arresting multiple kinase pathways along with STAT3-related proteins (Mcl-1 and Survivin). STAT3 silencing can also be accomplished by RNA interference and can increase the TTFields-sensitizing effect of sorafenib. If the effects are reversed and gene regulating STAT3 is expressed more, it annihilates the effects of treatment. Moreover, sorafenib plus TTFields significantly inhibited xenograft tumor growth and combinatorial treatment reduced STAT3 expression more effectively in vivo. These in vitro and in vivo results indicate that sorafenib tends to sensitize GBM cells to TTFields-induced apoptosis by inhibiting STAT3.
    Keywords:  STAT3; Tumor-treating fields; glioblastoma multiforme; sorafenib
  8. Oncogene. 2020 Nov 13.
    Kim JY, Kim HJ, Jung CW, Choi BI, Lee DH, Park MJ.
      PARK7 is involved in many key cellular processes, including cell proliferation, transcriptional regulation, cellular differentiation, oxidative stress protection, and mitochondrial function maintenance. Deregulation of PARK7 has been implicated in the pathogenesis of various human diseases, including cancer. Here, we aimed to clarify the effect of PARK7 on stemness and radioresistance of glioblastoma stem cells (GSCs). Serum differentiation and magnetic cell sorting of GSCs revealed that PARK7 was preferentially expressed in GSCs rather than differentiated GSCs. Immunohistochemical staining showed enhanced expression of PARK7 in glioma tissues compared to that in normal brain tissues. shRNA-mediated knockdown of PARK7 inhibited the self-renewal activity of GSCs in vitro, as evidenced by the results of neurosphere formation, limiting dilution, and soft-agar clonogenic assays. In addition, PARK7 knockdown suppressed GSC invasion and enhanced GSC sensitivity to ionizing radiation (IR). PARK7 knockdown suppressed expression of GSC signatures including nestin, epidermal growth factor receptor variant III (EGFRvIII), SOX2, NOTCH1, and OCT4. Contrarily, overexpression of PARK7 in CD133- non-GSCs increased self-renewal activities, migration, and IR resistance, and rescued the reduction of GSC factors under shPARK7-transfected and serum-differentiation conditions. Intriguingly, PARK7 acted as a co-chaperone of HSP90 by binding to it, protecting EGFRvIII from proteasomal degradation. Knockdown of PARK7 increased the production of reactive oxygen species, inducing partial apoptosis and enhancing IR sensitivity in GSCs. Finally, PARK7 knockdown increased mouse survival and IR sensitivity in vivo. Based on these data, we propose that PARK7 plays a pivotal role in the maintenance of stemness and therapeutic resistance in GSCs.
  9. Neuro Oncol. 2020 Nov 11. pii: noaa258. [Epub ahead of print]
    Berzero G, Di Stefano AL, Ronchi S, Bielle F, Villa C, Guillerm E, Capelle L, Mathon B, Laurenge A, Giry M, Schmitt Y, Marie Y, Idbaih A, Hoang-Xuan K, Delattre JY, Mokhtari K, Sanson M.
      BACKGROUND: IDH-wildtype (IDHwt) grade II gliomas are a rare and heterogeneous entity. Survival and prognostic factors are poorly defined.METHODS: We searched retrospectively all patients diagnosed with diffuse WHO grade II and III gliomas at our center (1989-2020).
    RESULTS: Out of 517 grade II gliomas, 47 were "diffuse astrocytomas, IDHwt". Tumors frequently had fronto-temporo-insular location (28/47, 60%) and infiltrative behavior. We found TERT promoter mutations (23/45, 51%), whole chromosome 7 gains (10/37, 27%), whole chromosome 10 losses (10/41, 24%), and EGFR amplifications (4/43, 9%) but no TP53 mutations (0/22, 0%). Median overall survival (OS) was 59 months (vs. 19 months for IDHwt grade III gliomas (p< 0.0001). Twenty-nine patients (29/43, 67%) met the definition of molecular glioblastoma according to cIMPACT-NOW update3. Median OS in this subset was 42 months, which was shorter compared to patients with IDHwt grade II gliomas not meeting this definition (median OS: 57 months), but substantially longer compared to IDHwt grade III gliomas meeting the definition for molecular glioblastoma (median OS: 17 months, p<0.0001). Most patients with IDHwt grade II gliomas met cIMPACT criteria because of isolated TERT promoter mutations (16/26, 62%), which were not predictive of poor outcome (median OS: 88 months). Actionable targets, including 5 gene fusions involving FGFR3, were found in 7 patients (24%).
    CONCLUSIONS: Our findings highlight the importance of histological grading and molecular profiling for the prognostic stratification of IDHwt gliomas and suggest some caution when assimilating IDHwt grade II gliomas to molecular glioblastomas, especially those with isolated TERT promoter mutation.
    Keywords:  Diffuse low grade gliomas; FGFR3; IDH-wildtype; gene fusion; molecular markers
  10. Front Immunol. 2020 ;11 582106
    Pearson JRD, Cuzzubbo S, McArthur S, Durrant LG, Adhikaree J, Tinsley CJ, Pockley AG, McArdle SEB.
      Glioblastoma multiforme (GBM) is the most frequently occurring primary brain tumor and has a very poor prognosis, with only around 5% of patients surviving for a period of 5 years or more after diagnosis. Despite aggressive multimodal therapy, consisting mostly of a combination of surgery, radiotherapy, and temozolomide chemotherapy, tumors nearly always recur close to the site of resection. For the past 15 years, very little progress has been made with regards to improving patient survival. Although immunotherapy represents an attractive therapy modality due to the promising pre-clinical results observed, many of these potential immunotherapeutic approaches fail during clinical trials, and to date no immunotherapeutic treatments for GBM have been approved. As for many other difficult to treat cancers, GBM combines a lack of immunogenicity with few mutations and a highly immunosuppressive tumor microenvironment (TME). Unfortunately, both tumor and immune cells have been shown to contribute towards this immunosuppressive phenotype. In addition, current therapeutics also exacerbate this immunosuppression which might explain the failure of immunotherapy-based clinical trials in the GBM setting. Understanding how these mechanisms interact with one another, as well as how one can increase the anti-tumor immune response by addressing local immunosuppression will lead to better clinical results for immune-based therapeutics. Improving therapeutic delivery across the blood brain barrier also presents a challenge for immunotherapy and future therapies will need to consider this. This review highlights the immunosuppressive mechanisms employed by GBM cancers and examines potential immunotherapeutic treatments that can overcome these significant immunosuppressive hurdles.
    Keywords:  GBM - Glioblastoma multiforme; combinatorial therapy; immune escape; immunotherapy; overview; treatment
  11. Genes Dev. 2020 Nov 12.
    Lawlor K, Marques-Torrejon MA, Dharmalingham G, El-Azhar Y, Schneider MD, Pollard SM, Rodríguez TA.
      There is increasing evidence demonstrating that adult neural stem cells (NSCs) are a cell of origin of glioblastoma. Here we analyzed the interaction between transformed and wild-type NSCs isolated from the adult mouse subventricular zone niche. We found that transformed NSCs are refractory to quiescence-inducing signals. Unexpectedly, we also demonstrated that these cells induce quiescence in surrounding wild-type NSCs in a cell-cell contact and Notch signaling-dependent manner. Our findings therefore suggest that oncogenic mutations are propagated in the stem cell niche not just through cell-intrinsic advantages, but also by outcompeting neighboring stem cells through repression of their proliferation.
    Keywords:  Notch; cell competition; glioblastoma; neural stem cells; quiescence