Brusatol Inhibits Proliferation and Invasion of Glioblastoma by Down-Regulating the Expression of ECM1

Brusatol (Bru), a Chinese herbal extract, has a variety of anti-tumor effects. However, little is known regarding its role and underlying mechanism in glioblastoma cells. Here, we found that Bru could inhibit the proliferation of glioblastoma cells in vivo and in vitro. Besides, it also had an inhibitory effect on human primary glioblastoma cells. RNA-seq analysis indicated that Bru possibly achieved these effects through inhibiting the expression of extracellular matrix protein 1 (ECM1). Down-regulating the expression of ECM1 via transfecting siRNA could weaken the proliferation and invasion of glioblastoma cells and promote the inhibitory effect of Bru treatment. Lentivirus-mediated overexpression of ECM1 could effectively reverse this weakening effect. Our findings indicated that Bru could inhibit the proliferation and invasion of glioblastoma cells by suppressing the expression of ECM1, and Bru might be a novel effective anticancer drug for glioblastoma cells.

Exploring the Pivotal Neurophysiologic and Therapeutic Potentials of Vitamin C in Glioma

Gliomas represent solely primary brain cancers of glial cell or neuroepithelial origin. Gliomas are still the most lethal human cancers despite modern innovations in both diagnostic techniques as well as therapeutic regimes. Gliomas have the lowest overall survival rate compared to other cancers 5 years after definitive diagnosis. The dietary intake of vitamin C has protective effect on glioma risk. Vitamin C is an essential compound that plays a vital role in the regulation of lysyl and prolyl hydroxylase activity. Neurons store high levels of vitamin C via sodium dependent-vitamin C transporters (SVCTs) to protect them from oxidative ischemia-reperfusion injury. Vitamin C is a water-soluble enzyme, typically seen as a powerful antioxidant in plants as well as animals. The key function of vitamin C is the inhibition of redox imbalance from reactive oxygen species produced via the stimulation of glutamate receptors. Gliomas absorb vitamin C primarily via its oxidized dehydroascorbate form by means of GLUT 1, 3, and 4 and its reduced form, ascorbate, by SVCT2. Vitamin C is able to preserve prosthetic metal ions like Fe2+ and Cu+ in their reduced forms in several enzymatic reactions as well as scavenge free radicals in order to safeguard tissues from oxidative damage. Therapeutic concentrations of vitamin C are able to trigger H2O2 generation in glioma. High-dose combination of vitamin C and radiation has a much more profound cytotoxic effect on primary glioblastoma multiforme cells compared to normal astrocytes. Control trials are needed to validate the use of vitamin C and standardization of the doses of vitamin C in the treatment of patients with glioma.

Microglial Cytokines Induce Invasiveness and Proliferation of Human Glioblastoma through Pyk2 and FAK Activation

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.

A Consensus Definition of Supratotal Resection for Anatomically Distinct Primary Glioblastoma: An AANS/CNS Section on Tumors Survey of Neurosurgical Oncologists

Introduction: Supratotal resection (SpTR) of glioblastoma may be associated with improved survival, but published results have varied in part from lack of consensus on the definition and appropriate use of SpTR. A previous small survey of neurosurgical oncologists with expertise performing SpTR found resection 1-2 cm beyond contrast enhancement was an acceptable definition and glioblastoma involving the right frontal and bilateral anterior temporal lobes were considered most amenable to SpTR. The general neurosurgical oncology community has not yet confirmed the practicality of this definition. Methods Seventy-six general neurosurgical oncology members of the AANS/CNS Tumor Section were surveyed using a crowdsourcing approach. Participants were presented with 11 definitions of SpTR and rated each definition’s appropriateness. Participants additionally reviewed magnetic resonance imaging for 10 anatomically distinct glioblastomas and assessed the tumor location's eloquence, perceived equipoise of enrolling patients in a randomized trial comparing gross total to SpTR, and their personal treatment plans. Results Fifty-two neurosurgeons (73.2%) agreed that resection 1-2 cm beyond contrast enhancement was an acceptable definition for SpTR. Cases were divided into three anatomically distinct groups by perceived equipoise between gross total and SpTR. The best clinical trial candidates were right anterior temporal (n=58, 76.3%) and right frontal (n=55, 73.3%) glioblastomas. Conclusion Support exists within the neurosurgical oncology community to adopt the proposed consensus definition of SpTR of glioblastoma and to treat right anterior temporal and right frontal glioblastomas using SpTR. A smaller proportion of general neurosurgical oncologists than SpTR experts consider SpTR feasible in the left anterior temporal lobe.

Wild-type isocitrate dehydrogenase under the spotlight in glioblastoma

Brain tumors actively reprogram their cellular metabolism to survive and proliferate, thus offering potential therapeutic opportunities. Over the past decade, extensive research has been done on mutant IDH enzymes as markers of good prognosis in glioblastoma, a highly aggressive brain tumor in adults with dismal prognosis. Yet, 95% of glioblastoma are IDH wild-type. Here, we review current knowledge about IDH wild-type enzymes and their putative role in mechanisms driving tumor progression. After a brief overview on tumor metabolic adaptation, we present the diverse metabolic function of IDH enzymes and their roles in glioblastoma initiation, progression and response to treatments. Finally, we will discuss wild-type IDH targeting in primary glioblastoma.

A connectivity signature for glioblastoma

Tumor cell extensions called tumor microtubes (TMs) in glioma resemble neurites during neurodevelopment and connect glioma cells to a network that has considerable relevance for tumor progression and therapy resistance. The determination of interconnectivity in individual tumors has been challenging and the impact of tumor cell connectivity on patient survival remained unresolved so far. Here, a connectivity signature from single-cell RNA-sequenced (scRNA-Seq) xenografted primary glioblastoma (GB) cells was established and clinically validated. Thirty-four of 40 connectivity genes were related to neurogenesis, neural tube development or glioma progression, including the TM-network-relevant GAP43 gene. Astrocytic-like and mesenchymal-like GB cells had the highest connectivity signature scores in scRNA-Seq data of patient-derived xenografts and patient samples. In 230 human GBs, high connectivity correlated with the mesenchymal expression subtype, TP53 wildtype, and with dismal patient survival. CHI3L1 was identified as a robust molecular marker of connectivity. Thus, the connectivity signature allows novel insights into brain tumor biology, provides a proof-of-principle that tumor cell connectivity is relevant for patients prognosis, and serves as a robust biomarker that can be used for future clinical trials.

CTIM-33. PHASE II TRIAL OF VACCINE IMMUNOTHERAPY IN PRIMARY GLIOBLASTOMA: ADJUNCTIVE AUTOLOGOUS DENDRITIC CELLS PULSED WITH LYSATE FROM IRRADIATED SELF-RENEWING AUTOLOGOUS TUMOR CELLS (AV-GBM-1)

In primary glioblastoma (GBM), overall survival (OS) is poor despite standard aggressive therapy. Adjunctive AV-GBM-1 vaccine immunotherapy may improve OS. In this multi-institutional phase II trial, key eligibility criteria for intent-to-treat (ITT) enrollment were: (1) primary GBM, (2) age < 70 years when GBM was resected, (3) successful GBM cell culture, (4) successful monocyte collection by leukapheresis, (5) KPS > 70 post-surgery, and (6) plan to treat with concurrent RT/TMZ. Dendritic cells (DC) were differentiated from monocytes by culturing in IL-4 and granulocyte-macrophage colony stimulating factor (GM-CSF). AV-GBM-1 consisted of autologous DC incubated with autologous tumor antigens contained in the lysate of irradiated cultured GBM cells. After recovery from RT/TMZ, doses were admixed with 500 mcg GM-CSF; up to 8 doses were injected subcutaneously over 6 months. Patients were not excluded by apparent progression or pseudo-progression post RT/TMZ. OS and progression-free-survival (PFS) were calculated from ITT enrollment. The success rate was 97% for both GBM cell cultures and collection of monocytes; 60/60 vaccines were successfully manufactured. Median age was 59 years. 57 patients received 392 injections. After two weekly injections there were significant increases in plasma lipocalin-2 and angiopoietin-1, and decreases in thrombospondin-5, angiotensinogen, and beta-fibroblast growth factor. The most common adverse events attributed to AV-GBM-1 were local injection site reactions (16%) and flu-like symptoms (10%). With follow up from 15.2 to 32 months, median PFS and OS were 10.3 (8.5,11.6 95% CI) and 16.0 (13.0,21.3 95% CI) months respectively. OS was better in the 25 patients who had methylguanine-methyltransferase (MGMT) methylation and/or isocitrate dehydrogenase (IDH) mutation. Age was not independently correlated with survival. From date of first injection, OS was not increased in 14 patients who were treated with alternating electrical tumor-treating fields. CONCLUSION: feasibility, safety, and PFS were encouraging. A phase III trial is in development. Clinicaltrials.gov NCT03400917.