Glioblastoma multiforme: Effect of hypoxia and hypoxia inducible factors on therapeutic approaches

Metabolic Reprogramming in Glioblastoma Multiforme: A Review of Pathways and Therapeutic Targets

Glioblastoma (GBM) is an aggressive and highly malignant primary brain tumor characterized by rapid growth and a poor prognosis for patients. Despite advancements in treatment, the median survival time for GBM patients remains low. One of the crucial challenges in understanding and treating GBMs involves its remarkable cellular heterogeneity and adaptability. Central to the survival and proliferation of GBM cells is their ability to undergo metabolic reprogramming. Metabolic reprogramming is a process that allows cancer cells to alter their metabolism to meet the increased demands of rapid growth and to survive in the often oxygen- and nutrient-deficient tumor microenvironment. These changes in metabolism include the Warburg effect, alterations in several key metabolic pathways including glutamine metabolism, fatty acid synthesis, and the tricarboxylic acid (TCA) cycle, increased uptake and utilization of glutamine, and more. Despite the complexity and adaptability of GBM metabolism, a deeper understanding of its metabolic reprogramming offers hope for developing more effective therapeutic interventions against GBMs.

Hypoxia-induced TGFBI maintains glioma stem cells by stabilizing EphA2

Rationale: Glioma stem cells (GSCs) have emerged as pivotal drivers of tumor malignancy, sustained by various microenvironmental factors, including immune molecules and hypoxia. In our previous study, we elucidated the significant role of transforming growth factor beta-induced protein (TGFBI), a protein secreted by M2-like tumor-associated macrophages, in promoting the malignant behavior of glioblastoma (GBM) under normoxic conditions. Building upon these findings, the objective of this study was to comprehensively explore the crucial role and underlying mechanisms of autocrine TGFBI in GSCs under hypoxic conditions. Methods: We quantified TGFBI expression in glioma specimens and datasets. In vitro and in vivo assays were employed to investigate the effects of TGFBI on sustaining self-renewal and tumorigenesis of GSCs under hypoxia. RNA-seq and LC-MS/MS were conducted to explore TGFBI signaling mechanisms. Results: TGFBI is preferentially expressed in GSCs under hypoxic conditions. Targeting TGFBI impair GSCs self-renewal and tumorigenesis. Mechanistically, TGFBI was upregulated by HIF1α in GSCs and predominantly activates the AKT-c-MYC signaling pathway in GSCs by stabilizing the EphA2 protein through preventing its degradation. Conclusion: TGFBI plays a crucial role in maintaining the stem cell properties of GSCs in the hypoxic microenvironment. Targeting the TGFBI/EphA2 axis emerges as a promising and innovative strategy for GBM treatment, with the potential to improve the clinical outcomes of patients.

Trace Metal Impurities Effects on the Formation of [64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM)

[64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM) is a radioactive hypoxia-targeting therapeutic agent being investigated in clinical trials for malignant brain tumors. For the quality management of [64Cu]Cu-ATSM, understanding trace metal impurities' effects on the chelate formation of 64Cu and ATSM is important. In this study, we conducted coordination chemistry studies on metal-ATSM complexes. First, the effects of nonradioactive metal ions (Cu2+, Ni2+, Zn2+, and Fe2+) on the formation of [64Cu]Cu-ATSM were evaluated. When the amount of Cu2+ or Ni2+ added was 1.2 mol or 288 mol, equivalent to ATSM, the labeling yield of [64Cu]Cu-ATSM fell below 90%. Little effect was observed even when excess amounts of Zn2+ or Fe2+ were added to the ATSM. Second, these metals were reacted with ATSM, and chelate formation was measured using ultraviolet-visible (UV-Vis) absorption spectra. UV-Vis spectra showed a rapid formation of Cu2+ and the ATSM complex upon mixing. The rate of chelate formation by Ni2+ and ATSM was lower than that by Cu-ATSM. Zn2+ and Fe2+ showed much slower reactions with the ATSM than Ni2+. Trace amounts of Ni2+, Zn2+, and Fe2+ showed little effect on [64Cu]Cu-ATSM' quality, while the concentration of impurity Cu2+ must be controlled. These results can provide process management tools for radiopharmaceuticals.

Advances in Glioblastoma Therapy: An Update on Current Approaches

Glioblastoma multiforme (GBM) is a primary malignant brain tumor characterized by a high grade of malignancy and an extremely unfavorable prognosis. The current efficacy of established treatments for GBM is insufficient, necessitating the prompt development of novel therapeutic approaches. The progress made in the fundamental scientific understanding of GBM is swiftly translated into more advanced stages of therapeutic studies. Despite extensive efforts to identify new therapeutic approaches, GBM exhibits a high mortality rate. The current efficacy of treatments for GBM patients is insufficient due to factors such as tumor heterogeneity, the blood-brain barrier, glioma stem cells, drug efflux pumps, and DNA damage repair mechanisms. Considering this, pharmacological cocktail therapy has demonstrated a growing efficacy in addressing these challenges. Towards this, various forms of immunotherapy, including the immune checkpoint blockade, chimeric antigen receptor T (CAR T) cell therapy, oncolytic virotherapy, and vaccine therapy have emerged as potential strategies for enhancing the prognosis of GBM. Current investigations are focused on exploring combination therapies to mitigate undesirable side effects and enhance immune responses against tumors. Furthermore, clinical trials are underway to evaluate the efficacy of several strategies to circumvent the blood-brain barrier (BBB) to achieve targeted delivery in patients suffering from recurrent GBM. In this review, we have described the biological and molecular targets for GBM therapy, pharmacologic therapy status, prominent resistance mechanisms, and new treatment approaches. We also discuss these promising therapeutic approaches to assess prospective innovative therapeutic agents and evaluated the present state of preclinical and clinical studies in GBM treatment. Overall, this review attempts to provide comprehensive information on the current status of GBM therapy.

Recent Progress in Fluorescent Probes for Real-Time Monitoring of Glioblastoma

Treating glioblastoma (GBM) by resecting to a large extent can prolong a patient's survival by controlling the tumor cells, but excessive resection may produce postoperative complications by perturbing the brain structures. Therefore, various imaging procedures have been employed to successfully diagnose and resect with utmost caution and to protect vital structural or functional features. Fluorescence tagging is generally used as an intraoperative imaging technique in glioma cells in collaboration with other surgical tools such as MRI and navigation methods. However, the existing fluorescent probes may have several limitations, including poor selectivity, less photostability, false signals, and intraoperative re-administration when used in clinical and preclinical studies for glioma surgery. The involvement of smart fluorogenic materials, specifically fluorescent dyes, and biomarker-amended cell-penetrable fluorescent probes have noteworthy advantages for precise glioma imaging. This review outlines the contemporary advancements of fluorescent probes for imaging glioma cells along with their challenges and visions, with the anticipation to develop next-generation smart glioblastoma detection modalities.

Delineating the glioblastoma stemness by genes involved in cytoskeletal rearrangements and metabolic alterations

Literature data on glioblastoma ongoingly underline the link between metabolism and cancer stemness, the latter is one responsible for potentiating the resistance to treatment, inter alia due to increased invasiveness. In recent years, glioblastoma stemness research has bashfully introduced a key aspect of cytoskeletal rearrangements, whereas the impact of the cytoskeleton on invasiveness is well known. Although non-stem glioblastoma cells are less invasive than glioblastoma stem cells (GSCs), these cells also acquire stemness with greater ease if characterized as invasive cells and not tumor core cells. This suggests that glioblastoma stemness should be further investigated for any phenomena related to the cytoskeleton and metabolism, as they may provide new invasion-related insights. Previously, we proved that interplay between metabolism and cytoskeleton existed in glioblastoma. Despite searching for cytoskeleton-related processes in which the investigated genes might have been involved, not only did we stumble across the relation to metabolism but also reported genes that were found to be implicated in stemness. Thus, dedicated research on these genes in GSCs seems justifiable and might reveal novel directions and/or biomarkers that could be utilized in the future. Herein, we review the previously identified cytoskeleton/metabolism-related genes through the prism of glioblastoma stemness.

Design and Computational Analysis of an MMP9 Inhibitor in Hypoxia-Induced Glioblastoma Multiforme

The main therapeutic difficulties in treating hypoxia-induced glioblastoma multiforme (GBM) are toxicity of current treatments and the resistance brought on by the microenvironment. More effective therapeutic alternatives are urgently needed to reduce tumor lethality. Hence, we screened plant-based natural product panels intending to identify novel drugs without elevating drug resistance. We explored GEO for the hypoxia GBM model and compared hypoxic genes to non-neoplastic brain cells. A total of 2429 differentially expressed genes expressed exclusively in hypoxia were identified. The functional enrichment analysis demonstrated genes associated with GBM, further PPI network was constructed, and biological pathways associated with them were explored. Seven webtools, including GEPIA2.0, TIMER2.0, TCGA-GBM, and GlioVis, were used to validate 32 hub genes discovered using Cytoscape tool in GBM patient samples. Four GBM-specific hypoxic hub genes, LYN, MMP9, PSMB9, and TIMP1, were connected to the tumor microenvironment using TIMER analysis. 11 promising hits demonstrated positive drug-likeness with nontoxic characteristics and successfully crossed blood-brain barrier and ADMET analyses. Top-ranking hits have stable intermolecular interactions with the MMP9 protein according to molecular docking, MD simulation, MM-PBSA, PCA, and DCCM analyses. Herein, we have reported flavonoids, 7,4'-dihydroxyflavan, (3R)-3-(4-hydroxybenzyl)-6-hydroxy-8-methoxy-3,4-dihydro-2H-1-benzopyran, and 4'-hydroxy-7-methoxyflavan, to inhibit MMP9, a novel hypoxia gene signature that could serve as a promising predictor in various clinical applications, including GBM diagnosis, prognosis, and targeted therapy.

A Rare Triploid Involving the Coexistence of Glioblastoma Multiforme, Arteriovenous Malformation and Intracranial Aneurysm: Illustrative Case and Literature Review

The coexistence of glioblastoma multiforme (GBM) and arteriovenous malformation (AVM) is rarely reported in the literature. According to the present literature, these GBM or glioma-related vascular malformations may present simultaneously in distinct regions of the brain or occur in the same area but at different times. So far, these distinct hypervascular glioblastomas have been described but are not classified as a separate pathological entities. Considering their heterogeneity and complexity, all the above mentioned cases remain challenging in diagnosis and therapeutic modality. Likewise, there is a paucity of data surrounding the simultaneous presentation of GBM with intracranial aneurysms. In the literature, the independent concurrence of these three intracranial lesions has never been reported. In this article, we present a case who suffered from intermittent headaches and dizziness initially and further radiographic examination revealed an internal carotid artery (ICA) aneurysm that occurred in the patient with coexisting GBM and AVM. Surgical intervention for tumor and AVM removal was performed smoothly. This patient underwent endovascular coiling for the ICA aneurysm 4 months postoperatively. In addition, we also review the current literature relating to this rare combination of medical conditions.

Measurement of Cerebral Oxygen Extraction Fraction Using Quantitative BOLD Approach: A Review

Quantification of brain oxygenation and metabolism, both of which are indicators of the level of brain activity, plays a vital role in understanding the cerebral perfusion and the pathophysiology of brain disorders. Magnetic resonance imaging (MRI), a widely used clinical imaging technique, which is very sensitive to magnetic susceptibility, has the possibility of substituting positron emission tomography (PET) in measuring oxygen metabolism. This review mainly focuses on the quantitative blood oxygenation level-dependent (qBOLD) method for the evaluation of oxygen extraction fraction (OEF) in the brain. Here, we review the theoretic basis of qBOLD, as well as existing acquisition and quantification methods. Some published clinical studies are also presented, and the pros and cons of qBOLD method are discussed as well.

New therapeutic strategies based on molecularly targeted therapy in glioblastoma – a case report and review of the literature

Glioblastomas are the most common and most lethal forms of malignant primary brain tumor. We present a case report of a patient with III-grade glioma who achieved stable disease (SD) and clinical improvement after trametinib administration. We also report a review of the literature to Current Treatment Guidelines of Glioblastoma and new therapeutic strategies based on molecularly targeted therapy. Traditional treatments, including surgery, radiotherapy, and chemotherapy, have many limitations concerning the prognosis of patients with glioblastomas. Unfortunately, these tumors’recur after primary resection in the majority of cases. There is no standard therapy for recurrence of GBM. Targeted therapy offers a promising new treatment strategy. Regardless of those outstanding results much more can be done in the field of therapeutic options. Most urgent concerns include potent combining molecular targeted therapy with other types of treatments, selecting a group of patients for whom they turn out to be the most beneficial, and addressing adverse events of these molecules.

Profiling and Bioinformatics Analyses of Differential Circular RNA Expression in Glioblastoma Multiforme Cells Under Hypoxia

The hypoxia microenvironment is highly associated with GBM's malignant phenotypes. CircRNAs were reported involved in GBM's biological characteristics and regulated by HIF-1α. However, the differential expression profile and role of circRNAs in GBM cells under hypoxia are still unclear. The expression profiles of circRNAs in LN229 and T98G under hypoxia were explored via circRNA sequencing analysis. Those circRNAs significantly dysregulated both in LN229 and T98G and could be found in circBase were selected and validated by qRT-PCR, RNase R digestion reaction, and Sanger sequencing. Normal cell line and fresh GBM tissues were also used for qRT-PCR validation. The roles of differentially expressed circRNAs were evaluated by bioinformatics analyses. There were 672 dysregulated circRNAs in LN229 and 698 dysregulated circRNAs in T98G. GO analysis indicated that the alteration of circRNA expression related to GBM cell's biogenesis and metabolism. KEGG analysis demonstrated that TGF-β signaling pathway, HIF-1 signaling pathway, and metabolism-related signaling pathway were closely associated with differentially expressed circRNAs under hypoxia. These results were confirmed by GSEA analysis. The 6 selected and dysregulated circRNAs both in LN229 and T98G including hsa_circ_0000745, hsa_circ_0020093, hsa_circ_0020094, hsa_circ_0000943, hsa_circ_0004874, and hsa_circ_0002359 were validated by qRT-PCR. Inhibition of hsa_circ_0000745 inhibited GBM cell's proliferation, migration, and invasion. HIF-1α centered circRNA-miRNA-mRNA networks analysis showed that the 6 validated circRNAs could cross-talk with 11 related miRNAs. The circRNA expressions are dysregulated in GBM cell under hypoxia. The 6 validated circRNAs could participate in GBM's development and progression when hypoxia occurs. They might be the candidates for prognostic markers and adjuvant therapeutics of GBM in the future.

Medical Device Advances in the Treatment of Glioblastoma

Despite decades of research and the growing emergence of new treatment modalities, Glioblastoma (GBM) frustratingly remains an incurable brain cancer with largely stagnant 5-year survival outcomes of around 5%. Historically, a significant challenge has been the effective delivery of anti-cancer treatment. This review aims to summarize key innovations in the field of medical devices, developed either to improve the delivery of existing treatments, for example that of chemo-radiotherapy, or provide novel treatments using devices, such as sonodynamic therapy, thermotherapy and electric field therapy. It will highlight current as well as emerging device technologies, non-invasive versus invasive approaches, and by doing so provide a detailed summary of evidence from clinical studies and trials undertaken to date. Potential limitations and current challenges are discussed whilst also highlighting the exciting potential of this developing field. It is hoped that this review will serve as a useful primer for clinicians, scientists, and engineers in the field, united by a shared goal to translate medical device innovations to help improve treatment outcomes for patients with this devastating disease.

Decoding the Heterogeneity of Malignant Gliomas by PET and MRI for Spatial Habitat Analysis of Hypoxia, Perfusion, and Diffusion Imaging: A Preliminary Study

Background

Tumor heterogeneity poses major clinical challenges in high-grade gliomas (HGGs). Quantitative radiomic analysis with spatial tumor habitat clustering represents an innovative, non-invasive approach to represent and quantify tumor microenvironment heterogeneity. To date, habitat imaging has been applied mainly on conventional magnetic resonance imaging (MRI), although virtually extendible to any imaging modality, including advanced MRI techniques such as perfusion and diffusion MRI as well as positron emission tomography (PET) imaging.

Objectives

This study aims to evaluate an innovative PET and MRI approach for assessing hypoxia, perfusion, and tissue diffusion in HGGs and derive a combined map for clustering of intra-tumor heterogeneity.

Materials and Methods

Seventeen patients harboring HGGs underwent a pre-operative acquisition of MR perfusion (PWI), Diffusion (dMRI) and 18F-labeled fluoroazomycinarabinoside (18F-FAZA) PET imaging to evaluate tumor vascularization, cellularity, and hypoxia, respectively. Tumor volumes were segmented on fluid-attenuated inversion recovery (FLAIR) and T1 post-contrast images, and voxel-wise clustering of each quantitative imaging map identified eight combined PET and physiologic MRI habitats. Habitats’ spatial distribution, quantitative features and histopathological characteristics were analyzed.

Results

A highly reproducible distribution pattern of the clusters was observed among different cases, particularly with respect to morphological landmarks as the necrotic core, contrast-enhancing vital tumor, and peritumoral infiltration and edema, providing valuable supplementary information to conventional imaging. A preliminary analysis, performed on stereotactic bioptic samples where exact intracranial coordinates were available, identified a reliable correlation between the expected microenvironment of the different spatial habitats and the actual histopathological features. A trend toward a higher representation of the most aggressive clusters in WHO (World Health Organization) grade IV compared to WHO III was observed.

Conclusion

Preliminary findings demonstrated high reproducibility of the PET and MRI hypoxia, perfusion, and tissue diffusion spatial habitat maps and correlation with disease-specific histopathological features.

The road-map for establishment of a prognostic molecular marker panel in glioma using liquid biopsy: current status and future directions

Gliomas are primary intracranial tumors with defined molecular markers available for precise diagnosis. The prognosis of glioma is bleak as there is an overlook of the dynamic crosstalk between tumor cells and components of the microenvironment. Herein, different phases of gliomagenesis are presented with reference to the role and involvement of secreted proteomic markers at various stages of tumor initiation and development. The secreted markers of inflammatory response, namely interleukin-6, tumor necrosis factor-α, interferon-ϒ, and kynurenine, proliferation markers human telomerase reverse transcriptase and microtubule-associated-protein-Tau, and stemness marker human-mobility-group-AThook-1 are involved in glial tumor initiation and growth. Further, hypoxia and angiogenic factors, heat-shock-protein-70, endothelial-growth-factor-receptor-1 and vascular endothelial growth factor play a major role in promoting vascularization and tumor volume expansion. Eventually, molecules such as matrix-metalloprotease-7 and intercellular adhesion molecule-1 contribute to the degradation and remodeling of the extracellular matrix, ultimately leading to glioma progression. Our study delineates the roadmap to develop and evaluate a non-invasive panel of secreted biomarkers using liquid biopsy for precisely evaluating disease progression, to accomplish a clinical translation.

Differentiated glioma cell-derived Fibromodulin activates Integrin-dependent Notch signaling in endothelial cells to promote tumor angiogenesis and growth

Cancer stem cells (CSCs) alone can initiate and maintain tumors, but the function of non-cancer stem cells (non-CSCs) that form the tumor bulk remains poorly understood. Proteomic analysis showed a higher abundance of the extracellular matrix small leucine-rich proteoglycan fibromodulin (FMOD) in the conditioned medium of differentiated glioma cells (DGCs), the equivalent of glioma non-CSCs, compared to that of glioma stem-like cells (GSCs). DGCs silenced for FMOD fail to cooperate with co-implanted GSCs to promote tumor growth. FMOD downregulation neither affects GSC growth and differentiation nor DGC growth and reprogramming in vitro. DGC-secreted FMOD promotes angiogenesis by activating integrin-dependent Notch signaling in endothelial cells. Furthermore, conditional silencing of FMOD in newly generated DGCs in vivo inhibits the growth of GSC-initiated tumors due to poorly developed vasculature and increases mouse survival. Collectively, these findings demonstrate that DGC-secreted FMOD promotes glioma tumor angiogenesis and growth through paracrine signaling in endothelial cells and identifies a DGC-produced protein as a potential therapeutic target in glioma.

Stem Cell Therapy in Limb Ischemia: State-of-Art, Perspective, and Possible Impacts of Endometrial-Derived Stem Cells

As an evidence-based performance, the rising incidence of various ischemic disorders has been observed across many nations. As a result, there is a growing need for the development of more effective regenerative approaches that could serve as main therapeutic strategies for the treatment of these diseases. From a cellular perspective, promoted complex inflammatory mechanisms, after inhibition of organ blood flow, can lead to cell death in all tissue types. In this case, using the stem cell technology provides a safe and regenerative approach for ischemic tissue revascularization and functional cell formation. Limb ischemia (LI) is one of the most frequent ischemic disease types and has been shown to have a promising regenerative response through stem cell therapy based on several clinical trials. Bone marrow-derived mononuclear cells (BM-MNCs), peripheral blood CD34-positive mononuclear cells (CD34+ PB-MNCs), mesenchymal stem cells (MSCs), and endothelial stem/progenitor cells (ESPCs) are the main, well-examined stem cell types in these studies. Additionally, our investigations reveal that endometrial tissue can be considered a suitable candidate for isolating new safe, effective, and feasible multipotent stem cells for limb regeneration. In addition to other teams’ results, our in-depth studies on endometrial-derived stem cells (EnSCs) have shown that these cells have translational potential for limb ischemia treatment. The EnSCs are able to generate diverse types of cells which are essential for limb reconstruction, including endothelial cells, smooth muscle cells, muscle cells, and even peripheral nervous system populations. Hence, the main object of this review is to present stem cell technology and evaluate its method of regeneration in ischemic limb tissue.

Increased Ascorbate Content of Glioblastoma Is Associated With a Suppressed Hypoxic Response and Improved Patient Survival

Glioblastoma multiforme is a challenging disease with limited treatment options and poor survival. Glioblastoma tumours are characterised by hypoxia that activates the hypoxia inducible factor (HIF) pathway and controls a myriad of genes that drive cancer progression. HIF transcription factors are regulated at the post-translation level via HIF-hydroxylases. These hydroxylases require oxygen and 2-oxoglutarate as substrates, and ferrous iron and ascorbate as cofactors. In this retrospective observational study, we aimed to determine whether ascorbate played a role in the hypoxic response of glioblastoma, and whether this affected patient outcome. We measured the ascorbate content and members of the HIF-pathway of clinical glioblastoma samples, and assessed their association with clinicopathological features and patient survival. In 37 samples (37 patients), median ascorbate content was 7.6 μg ascorbate/100 mg tissue, range 0.8 – 20.4 μg ascorbate/100 mg tissue. In tumours with above median ascorbate content, HIF-pathway activity as a whole was significantly suppressed (p = 0.005), and several members of the pathway showed decreased expression (carbonic anhydrase-9 and glucose transporter-1, both p < 0.01). Patients with either lower tumour HIF-pathway activity or higher tumour ascorbate content survived significantly longer than patients with higher HIF-pathway or lower ascorbate levels (p = 0.011, p = 0.043, respectively). Median survival for the low HIF-pathway score group was 362 days compared to 203 days for the high HIF-pathway score group, and median survival for the above median ascorbate group was 390 days, compared to the below median ascorbate group with 219 days. The apparent survival advantage associated with higher tumour ascorbate was more prominent for the first 8 months following surgery. These associations are promising, suggesting an important role for ascorbate-regulated HIF-pathway activity in glioblastoma that may impact on patient survival.

The Hallmarks of Glioblastoma: Heterogeneity, Intercellular Crosstalk and Molecular Signature of Invasiveness and Progression

In 2021 the World Health Organization published the fifth and latest version of the Central Nervous System tumors classification, which incorporates and summarizes a long list of updates from the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy work. Among the adult-type diffuse gliomas, glioblastoma represents most primary brain tumors in the neuro-oncology practice of adults. Despite massive efforts in the field of neuro-oncology diagnostics to ensure a proper taxonomy, the identification of glioblastoma-tumor subtypes is not accompanied by personalized therapies, and no improvements in terms of overall survival have been achieved so far, confirming the existence of open and unresolved issues. The aim of this review is to illustrate and elucidate the state of art regarding the foremost biological and molecular mechanisms that guide the beginning and the progression of this cancer, showing the salient features of tumor hallmarks in glioblastoma. Pathophysiology processes are discussed on molecular and cellular levels, highlighting the critical overlaps that are involved into the creation of a complex tumor microenvironment. The description of glioblastoma hallmarks shows how tumoral processes can be linked together, finding their involvement within distinct areas that are engaged for cancer-malignancy establishment and maintenance. The evidence presented provides the promising view that glioblastoma represents interconnected hallmarks that may led to a better understanding of tumor pathophysiology, therefore driving the development of new therapeutic strategies and approaches.

Adapt to Persist: Glioblastoma Microenvironment and Epigenetic Regulation on Cell Plasticity

Glioblastoma (GBM) is the most frequent and aggressive brain tumor, characterized by great resistance to treatments, as well as inter- and intra-tumoral heterogeneity. GBM exhibits infiltration, vascularization and hypoxia-associated necrosis, characteristics that shape a unique microenvironment in which diverse cell types are integrated. A subpopulation of cells denominated GBM stem-like cells (GSCs) exhibits multipotency and self-renewal capacity. GSCs are considered the conductors of tumor progression due to their high tumorigenic capacity, enhanced proliferation, invasion and therapeutic resistance compared to non-GSCs cells. GSCs have been classified into two molecular subtypes: proneural and mesenchymal, the latter showing a more aggressive phenotype. Tumor microenvironment and therapy can induce a proneural-to-mesenchymal transition, as a mechanism of adaptation and resistance to treatments. In addition, GSCs can transition between quiescent and proliferative substates, allowing them to persist in different niches and adapt to different stages of tumor progression. Three niches have been described for GSCs: hypoxic/necrotic, invasive and perivascular, enhancing metabolic changes and cellular interactions shaping GSCs phenotype through metabolic changes and cellular interactions that favor their stemness. The phenotypic flexibility of GSCs to adapt to each niche is modulated by dynamic epigenetic modifications. Methylases, demethylases and histone deacetylase are deregulated in GSCs, allowing them to unlock transcriptional programs that are necessary for cell survival and plasticity. In this review, we described the effects of GSCs plasticity on GBM progression, discussing the role of GSCs niches on modulating their phenotype. Finally, we described epigenetic alterations in GSCs that are important for stemness, cell fate and therapeutic resistance.

Enhanced proton treatment with a LDLR-ligand peptide-conjugated gold nanoparticles targeting the tumor microenvironment in an infiltrative brain tumor model

The tumor microenvironment (TME) of glioblastoma malforms (GBMs) contains tumor invasiveness factors, microvascular proliferation, migratory cancer stem cells and infiltrative tumor cells, which leads to tumor recurrence in the absence of effective drug delivery in a Blood Brain Barrier (BBB)-intact TME and radiological invisibility. Low-density lipoprotein receptor (LDLR) is abundant in the blood brain barrier and overexpressed in malignant glioma cells. This study aimed to treat the TME with transmitted proton sensitization of LDLR ligand-functionalized gold nanoparticles (ApoB@AuNPs) in an infiltrative F98 glioma rat model. BBB-crossing ApoB@AuNPs were selectively taken up in microvascular endothelial cells proliferation and pericyte invasion, which are therapeutic targets in the glioma TME. Proton sensitization treated the TME and bulk tumor volume with enhanced therapeutic efficacy by 67-75% compared to that with protons alone. Immunohistochemistry demonstrated efficient treatment of endothelial cell proliferation and migratory tumor cells of invasive microvessels in the TME with saving normal tissues. Taken together, these data indicate that the use of LDLR ligand-functionalized gold nanoparticles is a promising strategy to treat infiltrative malignant glioma while overcoming BBB crossing.

Glioblastoma multiforme (GBM): An overview of current therapies and mechanisms of resistance

Glioblastoma multiforme (GBM) is a WHO grade IV glioma and the most common malignant, primary brain tumor with a 5-year survival of 7.2%. Its highly infiltrative nature, genetic heterogeneity, and protection by the blood brain barrier (BBB) have posed great treatment challenges. The standard treatment for GBMs is surgical resection followed by chemoradiotherapy. The robust DNA repair and self-renewing capabilities of glioblastoma cells and glioma initiating cells (GICs), respectively, promote resistance against all current treatment modalities. Thus, durable GBM management will require the invention of innovative treatment strategies. In this review, we will describe biological and molecular targets for GBM therapy, the current status of pharmacologic therapy, prominent mechanisms of resistance, and new treatment approaches. To date, medical imaging is primarily used to determine the location, size and macroscopic morphology of GBM before, during, and after therapy. In the future, molecular and cellular imaging approaches will more dynamically monitor the expression of molecular targets and/or immune responses in the tumor, thereby enabling more immediate adaptation of tumor-tailored, targeted therapies.

An analysis of lesions associated with developmental venous anomalies

OBJECTIVE

The aim of this study was to describe different lesions and features associated with developmental venous anomalies (DVAs).

METHODS

The records and magnetic resonance imaging (MRI) images of 1,722 patients who underwent cranial MRI between 2010 and 2017 were retrospectively reviewed. It was found that 124 (7.2%) patients had DVAs, and 48 of these patients (38.7%) had additional anomalies accompanying DVAs. Of the patients with DVAs, 25 were female and 23 were male, with a mean age of 39.3 years (range, 3-77 years). MRI was performed in all the patients.

RESULTS

In addition to DVAs, cavernomas were present in 30 patients (62.5%), haematomas in 7 (14.5%), gliosis in 6 (12.5%), demyelinating plaques in 4 (8.3%) and a glioblastoma in 1 (2.2%). The mean diameter of the DVAs was 1.1mm and the mean diameter of the lesions was 17.4mm. The susceptibility weighted imaging (SWI) sequence was also applied to 12 patients with cavernomas. The relevant sequence in all of these patients contributed to the diagnosis.

CONCLUSION

Our study shows that DVAs can accompany a wide spectrum of lesions, especially cavernomas. Although their pathophysiology has not yet been clearly established, these lesions may have a common aetiology.

Hypoxia Transcriptomic Modifications Induced by Proton Irradiation in U87 Glioblastoma Multiforme Cell Line

In Glioblastoma Multiforme (GBM), hypoxia is associated with radioresistance and poor prognosis. Since standard GBM treatments are not always effective, new strategies are needed to overcome resistance to therapeutic treatments, including radiotherapy (RT). Our study aims to shed light on the biomarker network involved in a hypoxic (0.2% oxygen) GBM cell line that is radioresistant after proton therapy (PT). For cultivating cells in acute hypoxia, GSI’s hypoxic chambers were used. Cells were irradiated in the middle of a spread-out Bragg peak with increasing PT doses to verify the greater radioresistance in hypoxic conditions. Whole-genome cDNA microarray gene expression analyses were performed for samples treated with 2 and 10 Gy to highlight biological processes activated in GBM following PT in the hypoxic condition. We describe cell survival response and significant deregulated pathways responsible for the cell death/survival balance and gene signatures linked to the PT/hypoxia configurations assayed. Highlighting the molecular pathways involved in GBM resistance following hypoxia and ionizing radiation (IR), this work could suggest new molecular targets, allowing the development of targeted drugs to be suggested in association with PT.

The Role of 2-Oxoglutarate Dependent Dioxygenases in Gliomas and Glioblastomas: A Review of Epigenetic Reprogramming and Hypoxic Response

Gliomas are a heterogeneous group of cancers that predominantly arise from glial cells in the brain, but may also arise from neural stem cells, encompassing low-grade glioma and high-grade glioblastoma. Whereas better diagnosis and new treatments have improved patient survival for many cancers, glioblastomas remain challenging with a highly unfavorable prognosis. This review discusses a super-family of enzymes, the 2-oxoglutarate dependent dioxygenase enzymes (2-OGDD) that control numerous processes including epigenetic modifications and oxygen sensing, and considers their many roles in the pathology of gliomas. We specifically describe in more detail the DNA and histone demethylases, and the hypoxia-inducible factor hydroxylases in the context of glioma, and discuss the substrate and cofactor requirements of the 2-OGDD enzymes. Better understanding of how these enzymes contribute to gliomas could lead to the development of new treatment strategies.

Matrix Stiffness Modulates Patient-Derived Glioblastoma Cell Fates in Three-Dimensional Hydrogels

Cancer progression is known to be accompanied by changes in tissue stiffness. Previous studies have primarily employed immortalized cell lines and 2D hydrogel substrates, which do not recapitulate the 3D tumor niche. How matrix stiffness affects patient-derived cancer cell fate in 3D remains unclear. In this study, we report a matrix metalloproteinase-degradable poly(ethylene-glycol)-based hydrogel platform with brain-mimicking biochemical cues and tunable stiffness (40-26,600 Pa) for 3D culture of patient-derived glioblastoma xenograft (PDTX GBM) cells. Our results demonstrate that decreasing hydrogel stiffness enhanced PDTX GBM cell proliferation, and hydrogels with stiffness 240 Pa and below supported robust PDTX GBM cell spreading in 3D. PDTX GBM cells encapsulated in hydrogels demonstrated higher drug resistance than 2D control, and increasing hydrogel stiffness further enhanced drug resistance. Such 3D hydrogel platforms may provide a valuable tool for mechanistic studies of the role of niche cues in modulating cancer progression for different cancer types.

The Multifaceted Role of CMA in Glioma: Enemy or Ally?

Chaperone-mediated autophagy (CMA) is a catabolic pathway fundamental for cell homeostasis, by which specific damaged or non-essential proteins are degraded. CMA activity has three main levels of regulation. The first regulatory level is based on the targetability of specific proteins possessing a KFERQ-like domain, which can be recognized by specific chaperones and delivered to the lysosomes. Target protein unfolding and translocation into the lysosomal lumen constitutes the second level of CMA regulation and is based on the modulation of Lamp2A multimerization. Finally, the activity of some accessory proteins represents the third regulatory level of CMA activity. CMA's role in oncology has not been fully clarified covering both pro-survival and pro-death roles in different contexts. Taking all this into account, it is possible to comprehend the actual complexity of both CMA regulation and the cellular consequences of its activity allowing it to be elected as a modulatory and not only catabolic machinery. In this review, the role covered by CMA in oncology is discussed with a focus on its relevance in glioma. Molecular correlates of CMA importance in glioma responsiveness to treatment are described to identify new early efficacy biomarkers and new therapeutic targets to overcome resistance.

Challenges and Perspectives of Standard Therapy and Drug Development in High-Grade Gliomas

Despite their low incidence rate globally, high-grade gliomas (HGG) remain a fatal primary brain tumor. The recommended therapy often is incapable of resecting the tumor entirely and exclusively targeting the tumor leads to tumor recurrence and dismal prognosis. Additionally, many HGG patients are not well suited for standard therapy and instead, subjected to a palliative approach. HGG tumors are highly infiltrative and the complex tumor microenvironment as well as high tumor heterogeneity often poses the main challenges towards the standard treatment. Therefore, a one-fit-approach may not be suitable for HGG management. Thus, a multimodal approach of standard therapy with immunotherapy, nanomedicine, repurposing of older drugs, use of phytochemicals, and precision medicine may be more advantageous than a single treatment model. This multimodal approach considers the environmental and genetic factors which could affect the patient's response to therapy, thus improving their outcome. This review discusses the current views and advances in potential HGG therapeutic approaches and, aims to bridge the existing knowledge gap that will assist in overcoming challenges in HGG.

A Review of Newly Diagnosed Glioblastoma

Glioblastoma is an aggressive and inevitably recurrent primary intra-axial brain tumor with a dismal prognosis. The current mainstay of treatment involves maximally safe surgical resection followed by radiotherapy over a 6-week period with concomitant temozolomide chemotherapy followed by temozolomide maintenance. This review provides a summary of the epidemiological, clinical, histologic and genetic characteristics of newly diagnosed disease as well as the current standard of care and potential future therapeutic prospects.

A comparative study of brain tumor cells from different age and anatomical locations using 3D biomimetic hydrogels

Brain tumors exhibit vast genotypic and phenotypic diversity depending on patient age and anatomical location. Hydrogels hold great promise as 3D in vitro models for studying brain tumor biology and drug screening, yet previous studies were limited to adult glioblastoma cells, and most studies used immortalized cell lines. Here we report a hydrogel platform that supports the proliferation and invasion of patient-derived brain tumor cell cultures (PDCs) isolated from different patient age groups and anatomical locations. Hydrogel stiffness was tuned by varying poly(ethylene-glycol) concentration. Cell adhesive peptide (CGRDS), hyaluronic acid, and MMP-cleavable crosslinkers were incorporated to facilitate cell adhesion and cell-mediated degradation. Three PDC lines were compared including adult glioblastoma cells (aGBM), pediatric glioblastoma cells (pGBM), and diffuse pontine intrinsic glioma (DIPG). A commonly used immortalized adult glioblastoma cell line U87 was included as a control. PDCs displayed stiffness-dependent behavior, with 40 Pa hydrogel promoting faster tumor proliferation and invasion. Adult GBM cells exhibited faster proliferation than pediatric GBM, and DIPG showed slowest proliferation. These results suggest both patient age and tumor location affects brain tumor behaviors. Adult GBM PDCs also exhibited very different cell proliferation and morphology from U87. The hydrogel reported here can provide a useful tool for future studies to better understand how age and anatomical locations impacts brain tumor progression using 3D in vitro models.

The Role of Hypoxia and SRC Tyrosine Kinase in Glioblastoma Invasiveness and Radioresistance

Advances in functional imaging are supporting neurosurgery and radiotherapy for glioblastoma, which still remains the most aggressive brain tumor with poor prognosis. The typical infiltration pattern of glioblastoma, which impedes a complete surgical resection, is coupled with a high rate of invasiveness and radioresistance, thus further limiting efficient therapy, leading to inevitable and fatal recurrences. Hypoxia is of crucial importance in gliomagenesis and, besides reducing radiotherapy efficacy, also induces cellular and molecular mediators that foster proliferation and invasion. In this review, we aimed at analyzing the biological mechanism of glioblastoma invasiveness and radioresistance in hypoxic niches of glioblastoma. We also discussed the link between hypoxia and radiation-induced radioresistance with activation of SRC proto-oncogene non-receptor tyrosine kinase, prospecting potential strategies to overcome the current limitation in glioblastoma treatment.

Advances in drug delivery technology for the treatment of glioblastoma multiforme

Glioblastoma multiforme (GBM) is a particularly aggressive and malignant type of brain tumor, notorious for its high recurrence rate and low survival rate. The treatment of GBM is challenging mainly because several issues associated with the GBM microenvironment have not yet been resolved. These obstacles originate from a variety of factors such as genetics, anatomy, and cytology, all of which collectively hinder the treatment of GBM. Recent advances in materials and device engineering have presented new perspectives with regard to unconventional drug administration methods for GBM treatment. Such novel drug delivery approaches, based on the clear understanding of the intrinsic properties of GBM, have shown promise in overcoming some of the obstacles. In this review, we first recapitulate the first-line therapy and clinical challenges in the current treatment of GBM. Afterwards, we introduce the latest technological advances in drug delivery strategies to improve the efficiency for GBM treatment, mainly focusing on materials and devices. We describe such efforts by classifying them into two categories, systemic and local drug delivery. Finally, we discuss unmet challenges and prospects for the clinical translation of these drug delivery technologies.

Penta-fluorophenol: a Smiles rearrangement-inspired cysteine-selective fluorescent probe for imaging of human glioblastoma

Two of the most critical factors for the survival of glioblastoma (GBM) patients are precision diagnosis and the tracking of treatment progress. At the moment, various sophisticated and specific diagnostic procedures are being used, but there are relatively few simple diagnosis methods. This work introduces a sensing probe based on a turn-on type fluorescence response that can measure the cysteine (Cys) level, which is recognized as a new biomarker of GBM, in human-derived cells and within on-site human clinical biopsy samples. The Cys-initiated chemical reactions of the probe cause a significant fluorescence response with high selectivity, high sensitivity, a fast response time, and a two-photon excitable excitation pathway, which allows the imaging of GBM in both mouse models and human tissue samples. The probe can distinguish the GBM cells and disease sites in clinical samples from individual patients. Besides, the probe has no short or long-term toxicity and immune response. The present findings hold promise for application of the probe to a relatively simple and straightforward following of GBM at clinical sites.

Recent Trends of microRNA Significance in Pediatric Population Glioblastoma and Current Knowledge of Micro RNA Function in Glioblastoma Multiforme

Central nervous system tumors are a significant problem for modern medicine because of their location. The explanation of the importance of microRNA (miRNA) in the development of cancerous changes plays an important role in this respect. The first papers describing the presence of miRNA were published in the 1990s. The role of miRNA has been pointed out in many medical conditions such as kidney disease, diabetes, neurodegenerative disorder, arthritis and cancer. There are several miRNAs responsible for invasiveness, apoptosis, resistance to treatment, angiogenesis, proliferation and immunology, and many others. The research conducted in recent years analyzing this group of tumors has shown the important role of miRNA in the course of gliomagenesis. These particles seem to participate in many stages of the development of cancer processes, such as proliferation, angiogenesis, regulation of apoptosis or cell resistance to cytostatics.

Hypoxia, Inflammation and Necrosis as Determinants of Glioblastoma Cancer Stem Cells Progression

Tumor hypoxic microenvironment causes hypoxia inducible factor 1 alpha (HIF-1α) activation and necrosis with alarmins release. Importantly, HIF-1α also controls the expression of alarmin receptors in tumor cells that can bind to and be activated by alarmins. Human tumor tissues possess 1–2% of cancer stem cells (CSCs) residing in hypoxic niches and responsible for the metastatic potential of tumors. Our hypothesis is that hypoxic CSCs express alarmin receptors that can bind alarmins released during necrosis, an event favoring CSCs migration. To investigate this aspect, glioblastoma stem-like cell (GSC) lines were kept under hypoxia to determine the expression of hypoxic markers as well as receptor for advanced glycation end products (RAGE). The presence of necrotic extracts increased migration, invasion and cellular adhesion. Importantly, HIF-1α inhibition by digoxin or acriflavine prevented the response of GSCs to hypoxia alone or plus necrotic extracts. In vivo, GSCs injected in one brain hemisphere of NOD/SCID mice were induced to migrate to the other one in which a necrotic extract was previously injected. In conclusion, our results show that hypoxia is important not only for GSCs maintenance but also for guiding their response to external necrosis. Inhibition of hypoxic pathway may therefore represent a target for preventing brain invasion by glioblastoma stem cells (GSCs).

M2 Receptor Activation Counteracts the Glioblastoma Cancer Stem Cell Response to Hypoxia Condition

Glioblastoma multiforme (GBM) is the most malignant brain tumor. Hypoxic condition is a predominant feature of the GBM contributing to tumor growth and resistance to conventional therapies. Hence, the identification of drugs able to impair GBM malignancy and aggressiveness is considered of great clinical relevance. Previously, we demonstrated that the activation of M2 muscarinic receptors, through the agonist arecaidine propargyl ester (Ape), arrests cell proliferation in GBM cancer stem cells (GSCs). In the present work, we have characterized the response of GSCs to hypoxic condition showing an upregulation of hypoxia-inducible factors and factors involved in the regulation of GSCs survival and proliferation. Ape treatment in hypoxic conditions is however able to inhibit cell cycle progression, causing a significant increase of aberrant mitosis with consequent decreased cell survival. Additionally, qRT-PCR analysis suggest that Ape downregulates the expression of stemness markers and miR-210 levels, one of the main regulators of the responses to hypoxic condition in different tumor types. Our data demonstrate that Ape impairs the GSCs proliferation and survival also in hypoxic condition, negatively modulating the adaptive response of GSCs to hypoxia.

Nanocarrier-based drug combination therapy for glioblastoma

The current achievements in treating glioblastoma (GBM) patients are not sufficient because many challenges exist, such as tumor heterogeneity, the blood brain barrier, glioma stem cells, drug efflux pumps and DNA damage repair mechanisms. Drug combination therapies have shown increasing benefits against those challenges. With the help of nanocarriers, enhancement of the efficacy and safety could be gained using synergistic combinations of different therapeutic agents. In this review, we will discuss the major issues for GBM treatment, the rationales of drug combinations with or without nanocarriers and the principle of enhanced permeability and retention effect involved in nanomedicine-based tumor targeting and promising nanodiagnostics or -therapeutics. We will also summarize the recent progress and discuss the clinical perspectives of nanocarrier-based combination therapies. The goal of this article was to provide better understanding and key considerations to develop new nanomedicine combinations and nanotheranostics options to fight against GBM.

Nasal Drug Delivery of Anticancer Drugs for the Treatment of Glioblastoma: Preclinical and Clinical Trials

Glioblastoma (GBM) is the most lethal form of brain tumor, being characterized by the rapid growth and invasion of the surrounding tissue. The current standard treatment for glioblastoma is surgery, followed by radiotherapy and concurrent chemotherapy, typically with temozolomide. Although extensive research has been carried out over the past years to develop a more effective therapeutic strategy for the treatment of GBM, efforts have not provided major improvements in terms of the overall survival of patients. Consequently, new therapeutic approaches are urgently needed. Overcoming the blood–brain barrier (BBB) is a major challenge in the development of therapies for central nervous system (CNS) disorders. In this context, the intranasal route of drug administration has been proposed as a non-invasive alternative route for directly targeting the CNS. This route of drug administration bypasses the BBB and reduces the systemic side effects. Recently, several formulations have been developed for further enhancing nose-to-brain transport, mainly with the use of nano-sized and nanostructured drug delivery systems. The focus of this review is to provide an overview of the strategies that have been developed for delivering anticancer compounds for the treatment of GBM while using nasal administration. In particular, the specific properties of nanomedicines proposed for nose-to-brain delivery will be critically evaluated. The preclinical and clinical data considered supporting the idea that nasal delivery of anticancer drugs may represent a breakthrough advancement in the fight against GBM.

The role of p-Stat3 Y705 immunohistochemistry in glioblastoma prognosis

Background

In spite of the multimodal treatment used today, glioblastoma is still the most aggressive and lethal cerebral tumour. To increase survival in these patients, novel therapeutic targets must be discovered. Signal transducer and activator of transcription 3 (Stat3), a transcription factor that controls normal cell differentiation and survival is also involved in neoplastic celltransformation. In this study we evaluated the immunohistochemical expression of pY705-Stat3 in patients with primary glioblastoma and determined its prognostic role by correlating it with survival.

Methods

This retrospective study included 94 patients diagnosed with glioblastoma. We determined the localization, number of positive cells, and marker intensity for pY705-Stat3 in these patients with the use of immunohistochemistry. The prognostic role was determined by correlating pY705-Stat3 expression on formalin-fixed paraffin-embedded tumour tissues with the patient’s survival in univariate and multivariate COX regressions.

Results

We found a statistically significant difference in survival between the patients with more than 20% pY705-Stat3 positive cells and those with less than 20% pY705-Stat3 positive cells (8.9 months median survival versus 13.7 months medial survival, p <  0.001). On multivariate analyses with the COX proportional hazards regression model including pY705-Stat3 expression, age and relapse status, pY705-Stat3 status was an independent prognostic factor in glioblastoma (P <  0.001).

Conclusion

The results obtained show that the immunohistochemical expression of pY705-Stat3 correlates with survival in glioblastoma. This study identifies Stat3 as a possible target for existing or new developed Stat3 inhibitors.

Similarities Between Stem Cell Niches in Glioblastoma and Bone Marrow: Rays of Hope for Novel Treatment Strategies

Glioblastoma is the most aggressive primary brain tumor. Slowly dividing and therapy-resistant glioblastoma stem cells (GSCs) reside in protective peri-arteriolar niches and are held responsible for glioblastoma recurrence. Recently, we showed similarities between GSC niches and hematopoietic stem cell (HSC) niches in bone marrow. Acute myeloid leukemia (AML) cells hijack HSC niches and are transformed into therapy-resistant leukemic stem cells (LSCs). Current clinical trials are focussed on removal of LSCs out of HSC niches to differentiate and to become sensitized to chemotherapy. In the present study, we elaborated further on these similarities by immunohistochemical analyses of 17 biomarkers in paraffin sections of human glioblastoma and human bone marrow. We found all 17 biomarkers to be expressed both in hypoxic peri-arteriolar HSC niches in bone marrow and hypoxic peri-arteriolar GSC niches in glioblastoma. Our findings implicate that GSC niches are being formed in glioblastoma as a copy of HSC niches in bone marrow. These similarities between HSC niches and GSC niches provide a theoretic basis for the development of novel strategies to force GSCs out of their niches, in a similar manner as in AML, to induce GSC differentiation and proliferation to render them more sensitive to anti-glioblastoma therapies.

Bioactive lipids in cancer stem cells

Tumours are known to be a heterogeneous group of cells, which is why they are difficult to eradicate. One possible cause for this is the existence of slow-cycling cancer stem cells (CSCs) endowed with stem cell-like properties of self-renewal, which are responsible for resistance to chemotherapy and radiotherapy. In recent years, the role of lipid metabolism has garnered increasing attention in cancer. Specifically, the key roles of enzymes such as stearoyl-CoA desaturase-1 and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase in CSCs, have gained particular interest. However, despite accumulating evidence on the role of proteins in controlling lipid metabolism, very little is known about the specific role played by lipid products in CSCs. This review highlights recent findings on the role of lipid metabolism in CSCs, focusing on the specific mechanism by which bioactive lipids regulate the fate of CSCs and their involvement in signal transduction pathways.

Preclinical Pharmacokinetic and Safety Studies of Copper-Diacetyl-Bis(N4-Methylthiosemicarbazone) (Cu-ATSM): Translational Studies for Internal Radiotherapy

Hypoxia plays important roles in the prognosis of malignant brain tumors such as glioblastoma because it causes drug delivery deficiencies and the induction of hypoxia-inducible factor-1α in tumor cells. Extensive hypoxic areas are associated with poor prognosis of these fatal diseases. We previously reported that multiple administrations of the hypoxia-targeted internal radiotherapy agent ⁶⁴Cu-diacetyl-bis(N⁴-methylthiosemicarbazone) (⁶⁴Cu-ATSM), four times at intervals of 1 or 2 weeks, show antitumor effects in glioblastoma without treatment-related adverse events. Before initiating clinical trials, preclinical safety studies using Cu-ATSM composed of stable isotopes and its precursor ATSM were required to understand the potential risks of systemic and repeated chemical exposure of our investigational drug. In this study, the concentrations of Cu-ATSM and ATSM in mouse plasma after intravenous administration were determined by liquid chromatography–tandem mass spectrometry, and the half-lives were estimated to be 21.5 and 22.4 minutes for Cu-ATSM and ATSM, respectively. Based on this result, approach 2 of the current ICH M3 [R2] guideline was adopted, and a 7-day intravenous toxicity study was conducted in mice. Cu-ATSM and ATSM in a ratio of 2:25 mimicking our current investigational drug was used, and no adverse effects were observed when Cu-ATSM and ATSM were administered at 81 μg/kg. These results and those of previous studies suggest that our current investigational drug formulation containing Cu-ATSM and ATSM at a dose of 15 μg can be safely administered to patients once per week for 4 weeks for treatment with ⁶⁴Cu-ATSM.

Role of Metformin and AKT Axis Modulation in the Reversion of Hypoxia Induced TMZ-Resistance in Glioma Cells

Hypoxia is a key driver of tumor adaptation promoting tumor progression and resistance to therapy. Hypoxia related pathways might represent attractive targets for the treatment of Glioblastoma Multiforme (GBM), that up to date is characterized by a poor prognosis. Primary aim of this study was to investigate the role of hypoxia and hypoxia-related modifications in the effect of temozolomide (TMZ) given alone or in association with the antidiabetic agent Metformin (MET) or the PI3K/mTOR blocker, BEZ235. The study was conducted in the TMZ responsive U251 and resistant T98 GBM cells. Our results showed that during hypoxia, TMZ plus MET reduced viability of U251 cells affecting also CD133 and CD90 expressing cells. This effect was associated with a reduction of HIF-1α activity, VEGF release and AKT activation. In T98 TMZ-resistant cells, TMZ plus MET exerted similar effects on HIF-1α. However, in this cell line, TMZ plus MET failed to reduce CD133 positive cells and AKT phosphorylation. Nevertheless, the administration of the dual PI3K/mTOR inhibitor BEZ235 potentiated the effect of TMZ plus MET on cell viability, inducing a pro-apoptotic phenotype during hypoxic condition also in T98 cells, suggesting the block of the PI3K/AKT/mTOR pathway as a complementary target to further overcome GBM resistance during hypoxia. In conclusion, we proposed TMZ plus MET as suitable treatment to revert TMZ-resistance also during hypoxia, an effect potentiated by the inhibition of PI3K/mTOR axis.

The Small Molecule Ephrin Receptor Inhibitor, GLPG1790, Reduces Renewal Capabilities of Cancer Stem Cells, Showing Anti-Tumour Efficacy on Preclinical Glioblastoma Models

Therapies against glioblastoma (GBM) show a high percentage of failure associated with the survival of glioma stem cells (GSCs) that repopulate treated tumours. Forced differentiation of GSCs is a promising new approach in cancer treatment. Erythropoietin-producing hepatocellular (Eph) receptors drive tumourigenicity and stemness in GBM. We tested GLPG1790, a first small molecule with inhibition activity versus inhibitor of various Eph receptor kinases, in preclinical GBM models using in vitro and in vivo assays. GLPG1790 rapidly and persistently inhibited Ephrin-A1-mediated phosphorylation of Tyr⁵⁸⁸ and Ser⁸⁹⁷, completely blocking EphA2 receptor signalling. Similarly, this compound blocks the ephrin B2-mediated EphA3 and EphB4 tyrosine phosphorylation. This resulted in anti-glioma effects. GLPG1790 down-modulated the expression of mesenchymal markers CD44, Sox2, nestin, octamer-binding transcription factor 3/4 (Oct3/4), Nanog, CD90, and CD105, and up-regulated that of glial fibrillary acidic protein (GFAP) and pro-neural/neuronal markers, βIII tubulin, and neurofilaments. GLPG1790 reduced tumour growth in vivo. These effects were larger compared to radiation therapy (RT; U251 and T98G xenografts) and smaller than those of temozolomide (TMZ; U251 and U87MG cell models). By contrast, GLPG1790 showed effects that were higher than Radiotherapy (RT) and similar to Temozolomide (TMZ) in orthotopic U87MG and CSCs-5 models in terms of disease-free survival (DFS) and overall survival (OS). Further experiments were necessary to study possible interactions with radio- and chemotherapy. GLPG1790 demonstrated anti-tumor effects regulating both the differentiative status of Glioma Initiating Cells (GICs) and the quality of tumor microenvironment, translating into efficacy in aggressive GBM mouse models. Significant common molecular targets to radio and chemo therapy supported the combination use of GLPG1790 in ameliorative antiglioma therapy.

Targeting the Post-Irradiation Tumor Microenvironment in Glioblastoma via Inhibition of CXCL12

Radiotherapy is a mainstay in glioblastoma therapy as it not only directly targets tumor cells but also depletes the tumor microvasculature. The resulting intra-tumoral hypoxia initiates a chain of events that ultimately leads to re-vascularization, immunosuppression and, ultimately, tumor-regrowth. The key component of this cascade is overexpression of the CXC-motive chemokine ligand 12 (CXCL12), formerly known as stromal-cell derived factor 1 (SDF-1). We here review the role of CXCL12 in recruitment of pro-vasculogenic and immunosuppressive cells and give an overview on future and current drugs that target this axis.

Glioblastoma Multiforme Associated with Arteriovenous Malformation: A Case Report and Literature Review

Although microvascular proliferation can be observed in glioblastoma, obvious vascularity coupled with coexisting cerebral arteriovenous malformation (AVM) is extremely rare. This report is of a rare case of glioblastoma, coexisting with a cerebral AVM. A 20-year-old male presented with progressive right hemiparesis within 1 month. Cranial magnetic resonance imaging revealed a large bleeding tumor with surrounding dilated vessels. Cerebral angiography demonstrated a left frontal AVM with a 1.2 cm nidus. The patient underwent preoperative embolization and radical resection. The coincidence of glioma and AVM was a rare association. However, the concept of hypervascular glioblastoma has been used in different states from different literature reviews; therefore, the role of proangiogenic factors should be addressed