Cellular origin of glioblastoma and its implication in precision therapy

In silico prediction of GRP78-CRIPTO binding sites to improve therapeutic targeting in glioblastoma

Glioblastoma multiforme (GBM) is one of the most malignant tumors in central nervous system (CNS) tumors. The glucose-regulated protein 78 (GRP78) and CRIPTO (Cripto-1), a protein that belongs to the EGF-CFC (epidermal growth factor cripto-1 FRL-1 cryptic) family, are overexpressed in GBM. A complex between GRP78 SBDβ (substrate binding domain beta) and CRIPTO CFC domain was reported in previous studies. This complex activates MAPK/AKT signaling, Src/PI3K/AKT, and Smad2/3 pathways which is a reason for tumor proliferation. In this work, we study how the two proteins form the complex figuring out binding sites between GRP78 and CRIPTO utilizing computational biophysics and bioinformatics tools, such as protein-protein docking, molecular dynamics simulation and MMGBSA calculations. Haddock web server results of 4 regions from the CFC domain (region1 (- 70.4), region2 (- 78.7), region3 (- 74.2), region4 (- 86.8)) with selected residues of the SBDβ are then simulated for 100 ns MDS then MMGBSA were calculated for the four complexes. The results reveal the stability of the complexes with binding free energy (complex1 (- 15.07 kcal/mol), complex2 (- 59.78 kcal/mol), complex3 (- 81.92 kcal/mol), complex4 (- 126.26 kcal/mol). All these findings ensure that GRP78 SBDβ associates with the CRIPTO CFC domain, and the binding sites suggested make stable interactions between the proteins.

Tumor-associated long non-coding RNAs show variable expression across diffuse gliomas and effect on cell growth upon silencing in glioblastoma

Long noncoding RNAs (lncRNAs) have been recently recognized as critical components of cancer biology linked to oncogenic processes. Certain lncRNAs are known to act as oncogenes, and the disease-specific expression of many lncRNAs makes them informative biomarkers. We identified 22 uncharacterized lncRNAs from RNA-seq data of 169 glioblastoma (GBM) tumor samples sequenced by The Cancer Genome Atlas (TCGA) consortium and studied their expression in TCGA diffuse glioma cohort including also IDH-mutant astrocytomas and oligodendrogliomas as well as in normal brain samples from the Genotype-Tissue Expression cohort. All of the 22 lncRNAs were clearly upregulated in diffuse gliomas samples compared to the normal brain. Interestingly, 20 (91%) of these lncRNAs had significant expression differences between tumor grades and/or entities, and 14 (64%) were associated with overall patient survival. All 22 lncRNAs were expressed in at least one of the studied GBM cell lines and 10 (45%) were expressed in all four. When six of the lncRNAs were silenced in the SNB19 GBM cell line, the knock-down was associated with reduced growth and colony formation for three lncRNAs: TCONS_l2_00001282, lnc-GBMT-6, and lnc-NBN-1. In conclusion, the studied lncRNAs are associated with survival in patients with diffuse glioma and have functional relevance in GBM.

Neural cell competition sculpting brain from cradle to grave

Darwinian selection, operating within the cellular ecosystem of multicellular organisms, drives a pervasive surveillance mechanism of cell-cell competition that shapes tissue architecture and function. While cell competition eliminates suboptimal cells to ensure tissue integrity across various tissues, neuronal competition specifically sculpts neural networks to establish precise circuits for sensory, motor and cognitive functions. However, our understanding of cell competition across diverse neural cell types in both developmental and pathological contexts remains limited. Here, we review recent advances on the phenomenon, and mechanisms and potential functions of neural cell competition (NCC), ranging from neural progenitors, neurons, astrocytes and oligodendrocytes to microglia. Physiological NCC governs cellular survival, proliferation, arborization, organization, function and territorial colonization, whereas dysregulated NCC may cause neurodevelopmental disorders, accelerate aging, exacerbate neurodegenerative diseases and drive brain tumor progression. Future work that leverages cell competition mechanisms may help to improve cognition and curb diseases.

The Confluence of Nanotechnology and Heat Shock Protein 70 in Pioneering Glioblastoma Multiforme Therapy: Forging Pathways Towards Precision Targeting and Transformation

Heat-shock protein 70 (HSP70) and nanotechnology have emerged as promising avenues in glioblastoma multiforme (GBM) therapy, addressing the critical challenges posed by its aggressive nature and therapeutic resistance. HSP70's dual role in cellular stress response and tumour survival emphasises its potential as both a biomarker and therapeutic target. This review explores the innovative integration of HSP70 with nanotechnology, emphasising advancements in imaging, drug delivery and combination therapies. Nanoparticles, including SPIONs, liposomes, gold nanoparticles and metal-organic frameworks, demonstrate enhanced targeting and therapeutic efficacy through HSP70 modulation. Functionalized nanocarriers exploit HSP70's tumour-specific overexpression to improve drug delivery, minimise off-target effects and overcome the blood-brain barrier. Emerging strategies such as chemophototherapy, immunotherapy and photothermal therapy leverage HSP70's interactions within the tumour microenvironment, enabling synergistic treatment modalities. The review also highlights translational challenges, including heterogeneity of GBM, regulatory hurdles and variability in the enhanced permeability and retention (EPR) effect. Integrating computational modelling, personalised approaches and adaptive trial designs is crucial for clinical translation. By bridging nanotechnology and molecular biology, HSP70-targeted strategies hold transformative potential to redefine GBM diagnosis and treatment, offering hope for improved survival and quality of life. Trial Registration: ClinicalTrials.gov identifier: NCT00054041 and NCT04628806.

Inorganic and hybrid nanomaterials for NIR-II fluorescence imaging-guided therapy of Glioblastoma and perspectives

Glioblastoma (GBM) is the most invasive and lethal brain tumor, with limited therapeutic options due to its highly infiltrative nature, resistance to conventional therapies, and blood-brain barriers. Recent advancements in near-infrared II (NIR-II) fluorescence imaging have facilitated greater tissue penetration, improved resolution, and real-time visualization of GBM, providing a promising approach for precise diagnosis and treatment. The inorganic and hybrid NIR-II fluorescent materials have developed rapidly for NIR-II fluorescence imaging-guided diagnosis and therapy of many diseases, including GBM. Herein, we offer a timely update to explore the contribution of inorganic/hybrid NIR-II fluorescent nanomaterials, such as quantum dots, rare-earth-doped nanoparticles, carbon-based nanomaterials, and metal nanoclusters in imaging-guided treatment for GBM. These nanomaterials provide high photostability, strong fluorescence intensity, and tunable optical properties, allowing for multimodal imaging and enhanced therapeutic efficacy. Additionally, their integration with modern therapeutic strategies, such as photothermal therapy, chemodynamic therapy, photodynamic therapy, sonodynamic therapy, and immunotherapy, has shown significant potential in overcoming the limitations of traditional treatments. Looking forward, future advancements including safe body clearance, long-term biocompatibility, efficient BBB penetration, and extended emission wavelengths beyond 1500 nm could enhance the theranostic outcomes. The integration of dual imaging with immunotherapy and AI-driven strategies will further enhance precision and accelerate the clinical translation of smart theranostic platforms for GBM treatment.

Targeting cIAP2 in a novel senolytic strategy prevents glioblastoma recurrence after radiotherapy

Glioblastomas (GBM) are routinely treated with high doses of ionizing radiation (IR), yet these tumors recur quickly, and the recurrent tumors are highly therapy resistant. Here, we report that IR-induced senescence of tumor cells counterintuitively spurs GBM recurrence, driven by the senescence-associated secretory phenotype (SASP). We find that irradiated GBM cell lines and patient derived xenograft (PDX) cultures senesce rapidly in a p21-dependent manner. Senescent glioma cells upregulate SASP genes and secrete a panoply of SASP factors, prominently interleukin IL-6, an activator of the JAK-STAT3 pathway. These SASP factors collectively activate the JAK-STAT3 and NF-κB pathways in non-senescent GBM cells, thereby promoting tumor cell proliferation and SASP spreading. Transcriptomic analyses of irradiated GBM cells and the TCGA database reveal that the cellular inhibitor of apoptosis protein 2 (cIAP2), encoded by the BIRC3 gene, is a potential survival factor for senescent glioma cells. Senescent GBM cells not only upregulate BIRC3 but also induce BIRC3 expression and promote radioresistance in non-senescent tumor cells. We find that second mitochondria-derived activator of caspases (SMAC) mimetics targeting cIAP2 act as novel senolytics that trigger apoptosis of senescent GBM cells with minimal toxicity towards normal brain cells. Finally, using both PDX and immunocompetent mouse models of GBM, we show that the SMAC mimetic birinapant, administered as an adjuvant after radiotherapy, can eliminate senescent GBM cells and prevent the emergence of recurrent tumors. Taken together, our results clearly indicate that significant improvement in GBM patient survival may become possible in the clinic by eliminating senescent cells arising after radiotherapy.

Molecular biology of the deadliest cancer - glioblastoma: what do we know?

Glioblastomas are the most prevalent primary brain tumors and are associated with a dramatically poor prognosis. Despite an intensive treatment approach, including maximal surgical tumor removal followed by radio- and chemotherapy, the median survival for glioblastoma patients has remained around 18 months for decades. Glioblastoma is distinguished by its highly complex mechanisms of immune evasion and pronounced heterogeneity. This variability is apparent both within the tumor itself, which can exhibit multiple phenotypes simultaneously, and in its surrounding microenvironment. Another key feature of glioblastoma is its "cold" microenvironment, characterized by robust immunosuppression. Recent advances in single-cell RNA sequencing have uncovered new promising insights, revealing previously unrecognized aspects of this tumor. In this review, we consolidate current knowledge on glioblastoma cells and its microenvironment, with an emphasis on their biological properties and unique patterns of molecular communication through signaling pathways. The evidence underscores the critical need for personalized poly-immunotherapy and other approaches to overcome the plasticity of glioblastoma stem cells. Analyzing the tumor microenvironment of individual patients using single-cell transcriptomics and implementing a customized immunotherapeutic strategy could potentially improve survival outcomes for those facing this formidable disease.

Radiation-induced cellular plasticity primes glioblastoma for forskolin-mediated differentiation

Glioblastoma (GBM) is the deadliest brain cancer in adults, and all patients succumb to the tumor. While surgery followed by chemoradiotherapy delays disease progression, these treatments do not lead to tumor control, and targeted therapies or biologics have failed to further improve survival. Utilizing a transient radiation-induced state of multipotency, we used the adenylcyclase activator forskolin to alter the fate of irradiated glioma cells. The effects of the combined treatment on neuronal marker expression, cell cycle distribution, and proliferation were studied. Gene expression profiling was conducted using bulk RNA-seq. Changes in cell populations were investigated using single-cell RNA-seq. Effects on glioma stem cells (GSCs) were studied in extreme limiting dilution assays, and the effects on median survival were studied in both syngeneic and PDOX mouse models of GBM. The combined treatment induced the expression of neuronal markers in glioma cells, reduced proliferation, and led to a distinct gene expression profile. scRNA-seq revealed that the combined treatment forced glioma cells into a microglia- and neuron-like phenotype. In vivo, this treatment led to a loss of GSCs and prolonged median survival. Collectively, our data suggest that revisiting a differentiation therapy with forskolin in combination with radiation could lead to clinical benefit.

The role of lncRNAs in the interplay of signaling pathways and epigenetic mechanisms in glioma

Gliomas, highly aggressive tumors of the central nervous system, present overwhelming challenges due to their heterogeneity and therapeutic resistance. Glioblastoma multiforme (GBM), the most malignant form, underscores this clinical urgency due to dismal prognosis despite aggressive treatment regimens. Recent advances in cancer research revealed signaling pathways and epigenetic mechanisms that intricately govern glioma progression, offering multifaceted targets for therapeutic intervention. This review explores the dynamic interplay between signaling events and epigenetic regulation in the context of glioma, with a particular focus on the crucial roles played by non-coding RNAs (ncRNAs). Through direct and indirect epigenetic targeting, ncRNAs emerge as key regulators shaping the molecular landscape of glioblastoma across its various stages. By dissecting these intricate regulatory networks, novel and patient-tailored therapeutic strategies could be devised to improve patient outcomes with this devastating disease.

CAR-engineered NK cells versus CAR T cells in treatment of glioblastoma; strength and flaws

Glioblastoma (GBM) is a highly aggressive primary brain tumor that carries a grim prognosis. Because of the dearth of treatment options available for treatment of GBM, Chimeric Antigen Receptor (CAR)-engineered T cell and Natural Killer (NK) therapy could provide alternative strategies to address the challenges in GBM treatment. In these approaches, CAR T and NK cells are engineered for cancer-specific immunotherapy by recognizing surface antigens independently of major histocompatibility complex (MHC) molecules. However, the efficacy of CAR T cells is hindered by GBM's downregulation of its targeted antigens. CAR NK cells face similar challenges, but, in contrast, they offer advantages as off-the-shelf allogeneic products, devoid of graft-versus-host disease (GVHD) risk as well as anti-cancer activity beyond CAR specificity, potentially reducing the risk of relapse or resistance. Despite CAR T cell therapies being extensively studied in clinical settings, the use of CAR-modified NK cells in GBM treatment remains largely in the preclinical stage. This review aims to discuss recent advancements in NK cell and CAR T cell therapies for GBM, including methods for introducing CARs into both NK cells and T cells, addressing manufacturing challenges, and providing evidence supporting the efficacy of these approaches from preclinical and early-phase clinical studies. The comprehensive evaluation of CAR-engineered NK cells and CAR T cells seeks to identify the optimal therapeutic approach for GBM, contributing to the development of effective immunotherapies for this devastating disease.

Unveiling cell-type-specific microRNA networks through alternative polyadenylation in glioblastoma

BACKGROUND

Glioblastoma multiforme (GBM) is characterized by its cellular complexity, with a microenvironment consisting of diverse cell types, including oligodendrocyte precursor cells (OPCs) and neoplastic CD133 + radial glia-like cells. This study focuses on exploring the distinct cellular transitions in GBM, emphasizing the role of alternative polyadenylation (APA) in modulating microRNA-binding and post-transcriptional regulation.

RESULTS

Our research identified unique APA profiles that signify the transitional phases between neoplastic cells and OPCs, underscoring the importance of APA in cellular identity and transformation in GBM. A significant finding was the disconnection between differential APA events and gene expression alterations, indicating that APA operates as an independent regulatory mechanism. We also highlighted the specific genes in neoplastic cells and OPCs that lose microRNA-binding sites due to APA, which are crucial for maintaining stem cell characteristics and DNA repair, respectively. The constructed networks of microRNA-transcription factor-target genes provide insights into the cellular mechanisms influencing cancer cell survival and therapeutic resistance.

CONCLUSIONS

This study elucidates the APA-driven regulatory framework within GBM, spotlighting its influence on cell state transitions and microRNA network dynamics. Our comprehensive analysis using single-cell RNA sequencing data to investigate the microRNA-binding sites altered by APA profiles offers a robust foundation for future research, presenting a novel approach to understanding and potentially targeting the complex molecular interplay in GBM.

Amphiphilic hemicyanine molecular probes crossing the blood-brain barrier for intracranial optical imaging of glioblastoma

Intracranial optical imaging of glioblastoma (GBM) is challenging due to the scarcity of effective probes with blood-brain barrier (BBB) permeability and sufficient imaging depth. Herein, we describe a rational strategy for designing optical probes crossing the BBB based on an electron donor-π-acceptor system to adjust the lipid/water partition coefficient and molecular weight of probes. The amphiphilic hemicyanine dye (namely, IVTPO), which exhibits remarkable optical properties and effective BBB permeability, is chosen as an efficient fluorescence/photoacoustic probe for in vivo real-time imaging of orthotopic GBM with high resolution through the intact skull. Abnormal leakage of IVTPO adjacent to the developing tumor is unambiguously observed at an early stage of tumor development prior to impairment of BBB integrity, as assessed by commercial Evans blue (EB). Compared with EB, IVTPO demonstrates enhanced optical imaging capability and improved tumor-targeting efficacy. These results offer encouraging insights into medical diagnosis of intracranial GBM.

Effect of pyridoxine or cobalamin supplementation on apoptosis and cell cycle progression in a human glioblastoma cell line

Glioblastoma is the most aggressive type of brain tumor, with current therapies failing to significantly improve patient survival. Vitamins have important effects on cellular processes that are relevant for tumor development and progression.

AIM

The present study explored the effect of pyridoxine or cobalamin supplementation on the viability and cell cycle progression of human glioblastoma cell line U-87 MG.

METHOD

Cell cultures were treated with increasing concentrations of pyridoxine or cobalamin for 24-72 h. After supplementation, cell viability and cell cycle progression were assessed by spectrophotometry and flow cytometry. Analysis of Bcl-2 and active caspase 3 expression in supplemented cells was performed by western blot.

RESULT

The results show that pyridoxine supplementation decreases cell viability in a dose and time dependent manner. Loss of viability in pyridoxin-supplemented cells is probably related to less cell cycle progression, higher active caspase 3 expression and apoptosis. In addition, Bcl-2 expression did not appear to be altered by vitamin supplementation, but active caspase 3 expression was significantly increased in pyridoxine-, but not cobalamin-supplemented cells, furthermore, cobalamin inhibited the pyridoxine cytotoxicity in the cell viability assay when combined.

CONCLUSION

The results suggest that pyridoxine supplementation promotes apoptosis in human glioblastoma-derived cells and may be useful to enhance the effect of cytotoxic therapies in vivo.

Mitogen-activated protein kinase kinase kinase 1 facilitates the temozolomide resistance and migration of GBM via the MEK/ERK signalling

Mitogen-Activated Protein Kinase Kinase Kinase 1 (MAP3K1) is overexpressed in gliomas; however, its clinical significance, biological functions, and underlying molecular mechanisms remain unclear. Abnormal overexpression of MAP3K1 in glioma is strongly associated with unfavourable clinicopathological characteristics and disease progression. MAP3K1 could potentially serve as a reliable diagnostic and prognostic biomarker for glioma. MAP3K1 silencing suppressed the migration but had no effect on the proliferation and cell death of Glioblastoma Multiforme (GBM) cells. MAP3K1 knockdown exacerbated the temozolomide (TMZ) induced inhibition of glioma cell proliferation and death of GBM cells. In addition, MAP3K1 knockdown combined with TMZ treatment significantly inhibited the growth and increased cell death in organoids derived from GBM patients. MAP3K1 knockdown reversed TMZ resistance of GBM in intracranial glioma model. In terms of molecular mechanisms, the phosphorylation level of ERK was significantly decreased by MAP3K1 silencing. No significant change in the JNK pathway was found in MAP3K1-silenced GBM cells. Inhibition of ERK phosphorylation suppressed the migration and enhanced the TMZ sensibility of GBM cells. MAP3K1 was correlated with the immune infiltration in glioma. MAP3K1 could facilitate the migration and TMZ resistance of GBM cells through MEK/ERK signalling.

Neural Influences on Tumor Progression Within the Central Nervous System

For decades, researchers have studied how brain tumors, the immune system, and drugs interact. With the advances in cancer neuroscience, which centers on defining and therapeutically targeting nervous system-cancer interactions, both within the local tumor microenvironment (TME) and on a systemic level, the subtle relationship between neurons and tumors in the central nervous system (CNS) has been deeply studied. Neurons, as the executors of brain functional activities, have been shown to significantly influence the emergence and development of brain tumors, including both primary and metastatic tumors. They engage with tumor cells via chemical or electrical synapses, directly regulating tumors or via intricate coupling networks, and also contribute to the TME through paracrine signaling, secreting proteins that exert regulatory effects. For instance, in a study involving a mouse model of glioblastoma, the authors observed a 42% increase in tumor volume when neuronal activity was stimulated, compared to controls (p < 0.01), indicating a direct correlation between neural activity and tumor growth. These thought-provoking results offer promising new strategies for brain tumor therapies, highlighting the potential of neuronal modulation to curb tumor progression. Future strategies may focus on developing drugs to inhibit or neutralize proteins and other bioactive substances secreted by neurons, break synaptic connections and interactions between infiltrating cells and tumor cells, as well as disrupt electrical coupling within glioma cell networks. By harnessing the insights gained from this research, we aspire to usher in a new era of brain tumor therapies that are both more potent and precise.

Magnetic Hyperthermia in Glioblastoma Multiforme Treatment

Glioblastoma multiforme (GBM) represents one of the most critical oncological diseases in neurological practice, being considered highly aggressive with a dismal prognosis. At a worldwide level, new therapeutic methods are continuously being researched. Magnetic hyperthermia (MHT) has been investigated for more than 30 years as a solution used as a single therapy or combined with others for glioma tumor assessment in preclinical and clinical studies. It is based on magnetic nanoparticles (MNPs) that are injected into the tumor, and, under the effect of an external alternating magnetic field, they produce heat with temperatures higher than 42 °C, which determines cancer cell death. It is well known that iron oxide nanoparticles have received FDA approval for anemia treatment and to be used as contrast substances in the medical imagining domain. Today, energetic, efficient MNPs are developed that are especially dedicated to MHT treatments. In this review, the subject's importance will be emphasized by specifying the number of patients with cancer worldwide, presenting the main features of GBM, and detailing the physical theory accompanying the MHT treatment. Then, synthesis routes for thermally efficient MNP manufacturing, strategies adopted in practice for increasing MHT heat performance, and significant in vitro and in vivo studies are presented. This review paper also includes combined cancer therapies, the main reasons for using these approaches with MHT, and important clinical studies on human subjects found in the literature. This review ends by describing the most critical challenges associated with MHT and future perspectives. It is concluded that MHT can be successfully and regularly applied as a treatment for GBM if specific improvements are made.

Deep learning models for rapid discrimination of high-grade gliomas from solitary brain metastases using multi-plane T1-weighted contrast-enhanced (T1CE) images

Background

High-grade gliomas (HGG) and solitary brain metastases (SBM) are two common types of brain tumors in middle-aged and elderly patients. HGG and SBM display a high degree of similarity on magnetic resonance imaging (MRI) images. Consequently, differential diagnosis using preoperative MRI remains challenging. This study developed deep learning models that used pre-operative T1-weighted contrast-enhanced (T1CE) MRI images to differentiate between HGG and SBM before surgery.

Methods

By comparing various convolutional neural network models using T1CE image data from The First Medical Center of the Chinese PLA General Hospital and The Second People's Hospital of Yibin (Data collection for this study spanned from January 2016 to December 2023), it was confirmed that the GoogLeNet model exhibited the highest discriminative performance. Additionally, we evaluated the individual impact of the tumoral core and peritumoral edema regions on the network's predictive performance. Finally, we adopted a slice-based voting method to assess the accuracy of the validation dataset and evaluated patient prediction performance on an additional test dataset.

Results

The GoogLeNet model, in a five-fold cross-validation using multi-plane T1CE slices (axial, coronal, and sagittal) from 180 patients, achieved an average patient accuracy of 92.78%, a sensitivity of 95.56%, and a specificity of 90.00%. Moreover, on an external test set of 29 patients, the model achieved an accuracy of 89.66%, a sensitivity of 90.91%, and a specificity of 83.33%, with an area under the curve of 0.939 [95% confidence interval (CI): 0.842-1.000].

Conclusions

GoogLeNet performed better than previous methods at differentiating HGG from SBM, even for core and peritumoral edema in both. HGG and SBM could be fast screened using this end-to-end approach, improving workflow for both tumor treatments.

Gene expression profiling and the isocitrate dehydrogenase mutational landscape of temozolomide‑resistant glioblastoma

Glioblastoma multiforme (GBM) is an aggressive brain cancer that occurs more frequently than other brain tumors. The present study aimed to reveal a novel mechanism of temozolomide resistance in GBM using bioinformatics and wet lab analyses, including meta-Z analysis, Kaplan-Meier survival analysis, protein-protein interaction (PPI) network establishment, cluster analysis of co-expressed gene networks, and hierarchical clustering of upregulated and downregulated genes. Next-generation sequencing and quantitative PCR analyses revealed downregulated [tyrosine kinase with immunoglobulin and epidermal growth factor homology domains 1 (TIE1), calcium voltage-gated channel auxiliary subunit α2Δ1 (CACNA2D1), calpain 6 (CAPN6) and a disintegrin and metalloproteinase with thrombospondin motifs 6 (ADAMTS6)] and upregulated [serum amyloid (SA)A1, SAA2, growth differentiation factor 15 (GDF15) and ubiquitin specific peptidase 26 (USP26)] genes. Different statistical models were developed for these genes using the Z-score for P-value conversion, and Kaplan-Meier plots were constructed using several patient cohorts with brain tumors. The highest number of nodes was observed in the PPI network was for ADAMTS6 and TIE1. The PPI network model for all genes contained 35 nodes and 241 edges. Immunohistochemical staining was performed using isocitrate dehydrogenase (IDH)-wild-type or IDH-mutant GBM samples from patients and a significant upregulation of TIE1 (P<0.001) and CAPN6 (P<0.05) protein expression was demonstrated in IDH-mutant GBM in comparison with IDH-wild-type GBM. Structural analysis revealed an IDH-mutant model demonstrating the mutant residues (R132, R140 and R172). The findings of the present study will help the future development of novel biomarkers and therapeutics for brain tumors.

Utilizing human cerebral organoids to model breast cancer brain metastasis in culture

BACKGROUND

Metastasis, the spread, and growth of malignant cells at secondary sites within a patient's body, accounts for over 90% of cancer-related mortality. Breast cancer is the most common tumor type diagnosed and the leading cause of cancer lethality in women in the United States. It is estimated that 10-16% breast cancer patients will have brain metastasis. Current therapies to treat patients with breast cancer brain metastasis (BCBM) remain palliative. This is largely due to our limited understanding of the fundamental molecular and cellular mechanisms through which BCBM progresses, which represents a critical barrier for the development of efficient therapies for affected breast cancer patients.

METHODS

Previous research in BCBM relied on co-culture assays of tumor cells with rodent neural cells or rodent brain slice ex vivo. Given the need to overcome the obstacle for human-relevant host to study cell-cell communication in BCBM, we generated human embryonic stem cell-derived cerebral organoids to co-culture with human breast cancer cell lines. We used MDA-MB-231 and its brain metastatic derivate MDA-MB-231 Br-EGFP, other cell lines of MCF-7, HCC-1806, and SUM159PT. We leveraged this novel 3D co-culture platform to investigate the crosstalk of human breast cancer cells with neural cells in cerebral organoid.

RESULTS

We found that MDA-MB-231 and SUM159PT breast cancer cells formed tumor colonies in human cerebral organoids. Moreover, MDA-MB-231 Br-EGFP cells showed increased capacity to invade and expand in human cerebral organoids.

CONCLUSIONS

Our co-culture model has demonstrated a remarkable capacity to discern the brain metastatic ability of human breast cancer cells in cerebral organoids. The generation of BCBM-like structures in organoid will facilitate the study of human tumor microenvironment in culture.

The tumour microenvironment, treatment resistance and recurrence in glioblastoma

The adaptability of glioblastoma (GBM) cells, encouraged by complex interactions with the tumour microenvironment (TME), currently renders GBM an incurable cancer. Despite intensive research, with many clinical trials, GBM patients rely on standard treatments including surgery followed by radiation and chemotherapy, which have been observed to induce a more aggressive phenotype in recurrent tumours. This failure to improve treatments is undoubtedly a result of insufficient models which fail to incorporate components of the human brain TME. Research has increasingly uncovered mechanisms of tumour-TME interactions that correlate to worsened patient prognoses, including tumour-associated astrocyte mitochondrial transfer, neuronal circuit remodelling and immunosuppression. This tumour hijacked TME is highly implicated in driving therapy resistance, with further alterations within the TME and tumour resulting from therapy exposure inducing increased tumour growth and invasion. Recent developments improving organoid models, including aspects of the TME, are paving an exciting future for the research and drug development for GBM, with the hopes of improving patient survival growing closer. This review focuses on GBMs interactions with the TME and their effect on tumour pathology and treatment efficiency, with a look at challenges GBM models face in sufficiently recapitulating this complex and highly adaptive cancer.

Protective effects of silymarin in glioblastoma cancer cells through redox system regulation

BACKGROUND

Glioblastoma multiforme, a deadly form of brain tumor, is characterized by aggressive growth and poor prognosis. Oxidative stress, a disruption in the balance between antioxidants and oxidants, is a crucial factor in its pathogenesis. Silymarin, a flavonoid extracted from milk thistle, has shown therapeutic potential in inhibiting cancer cell growth, promoting apoptosis, and reducing inflammation. It also regulates oxidative stress. This study aims to investigate the regulatory effects of silymarin on oxidative stress parameters, especially the transcription factor Nrf2 and its related enzymes in GBM cancer cells, to develop a new anti-cancer compound with low toxicity.

METHODS AND RESULTS

First, the cytotoxicity of silymarin on U-87 MG cells was investigated by MTT and the results showed an IC50 of 264.6 μM. Then, some parameters of the redox system were measured with commercial kits, and the obtained results showed that silymarin increased the activity of catalase and superoxide dismutase enzymes, as well as the total antioxidant capacity levels; while the malondialdehyde level that is an indicator of lipid peroxidation was decreased by this compound. The expression level of Nrf2 and HO-1 and glutaredoxin and thioredoxin enzymes were checked by real-time PCR method, and the expression level increased significantly after treatment.

CONCLUSIONS

Our findings suggest that silymarin may exert its cytotoxic and anticancer effects by enhancing the Nrf2/HO-1 pathway through antioxidant mechanisms in U-87 MG cells.

Glioblastoma mechanobiology at multiple length scales

Glioblastoma multiforme (GBM), a primary brain cancer, is one of the most aggressive forms of human cancer, with a very low patient survival rate. A characteristic feature of GBM is the diffuse infiltration of tumor cells into the surrounding brain extracellular matrix (ECM) that provide biophysical, topographical, and biochemical cues. In particular, ECM stiffness and composition is known to play a key role in controlling various GBM cell behaviors including proliferation, migration, invasion, as well as the stem-like state and response to chemotherapies. In this review, we discuss the mechanical characteristics of the GBM microenvironment at multiple length scales, and how biomaterial scaffolds such as polymeric hydrogels, and fibers, as well as microfluidic chip-based platforms have been employed as tissue mimetic models to study GBM mechanobiology. We also highlight how such tissue mimetic models can impact the field of GBM mechanobiology.

Radiation-Induced Cellular Plasticity: A Strategy for Combatting Glioblastoma

Glioblastoma is the deadliest brain cancer in adults and almost all patients succumb to the tumor. While surgery followed by chemo-radiotherapy significantly delays disease progression, these treatments do not lead to long-term tumor control and targeted therapies or biologics have so far failed to further improve survival. Utilizing a transient radiation-induced state of multipotency we used the adenylcyclase activator forskolin to alter the cellular fate of glioma cells in response to radiation. The combined treatment induced the expression of neuronal markers in glioma cells, reduced proliferation and led to a distinct gene expression profile. scRNAseq revealed that the combined treatment forced glioma cells into a microglia- and neuron-like phenotypes. In vivo this treatment led to a loss of glioma stem cells and prolonged median survival in mouse models of glioblastoma. Collectively, our data suggest that revisiting a differentiation therapy with forskolin in combination with radiation could lead to clinical benefit.

Grading of glioma tumors using digital holographic microscopy

Gliomas are the most common type of cerebral tumors; they occur with increasing incidence in the last decade and have a high rate of mortality. For efficient treatment, fast accurate diagnostic and grading of tumors are imperative. Presently, the grading of tumors is established by histopathological evaluation, which is a time-consuming procedure and relies on the pathologists' experience. Here we propose a supervised machine learning procedure for tumor grading which uses quantitative phase images of unstained tissue samples acquired by digital holographic microscopy. The algorithm is using an extensive set of statistical and texture parameters computed from these images. The procedure has been able to classify six classes of images (normal tissue and five glioma subtypes) and to distinguish between gliomas types from grades II to IV (with the highest sensitivity and specificity for grade II astrocytoma and grade III oligodendroglioma and very good scores in recognizing grade III anaplastic astrocytoma and grade IV glioblastoma). The procedure bolsters clinical diagnostic accuracy, offering a swift and reliable means of tumor characterization and grading, ultimately the enhancing treatment decision-making process.

Nose-to-brain selective drug delivery to glioma via ferritin-based nanovectors reduces tumor growth and improves survival rate

Gliomas are among the most fatal tumors, and the available therapeutic options are very limited. Additionally, the blood-brain barrier (BBB) prevents most drugs from entering the brain. We designed and produced a ferritin-based stimuli-sensitive nanocarrier with high biocompatibility and water solubility. It can incorporate high amounts of the potent topoisomerase 1 inhibitor Genz-644282. Here, we show that this nanocarrier, named The-0504, can cross the BBB and specifically deliver the payload to gliomas that express high amounts of the ferritin/transferrin receptor TfR1 (CD71). Intranasal or intravenous administration of The-0504 both reduce tumor growth and improve the survival rate of glioma-bearing mice. However, nose-to-brain administration is a simpler and less invasive route that may spare most of the healthy tissues compared to intravenous injections. For this reason, the data reported here could pave the way towards a new, safe, and direct ferritin-based drug delivery method for brain diseases, especially brain tumors.

MiR-128-3p - a gray eminence of the human central nervous system

MicroRNA-128-3p (miR-128-3p) is a versatile molecule with multiple functions in the physiopathology of the human central nervous system. Perturbations of miR-128-3p, which is enriched in the brain, contribute to a plethora of neurodegenerative disorders, brain injuries, and malignancies, as this miRNA is a crucial regulator of gene expression in the brain, playing an essential role in the maintenance and function of cells stemming from neuronal lineage. However, the differential expression of miR-128-3p in pathologies underscores the importance of the balance between its high and low levels. Significantly, numerous reports pointed to miR-128-3p as one of the most depleted in glioblastoma, implying it is a critical player in the disease's pathogenesis and thus may serve as a therapeutic agent for this most aggressive form of brain tumor. In this review, we summarize the current knowledge of the diverse roles of miR-128-3p. We focus on its involvement in the neurogenesis and pathophysiology of malignant and neurodegenerative diseases. We also highlight the promising potential of miR-128-3p as an antitumor agent for the future therapy of human cancers, including glioblastoma, and as the linchpin of brain development and function, potentially leading to the development of new therapies for neurological conditions.

Glioblastoma-Associated Mesenchymal Stem/Stromal Cells and Cancer-Associated Fibroblasts: Partners in Crime?

Tumor-associated mesenchymal stem/stromal cells (TA-MSCs) have been recognized as attractive therapeutic targets in several cancer types, due to their ability to enhance tumor growth and angiogenesis and their contribution to an immunosuppressive tumor microenvironment (TME). In glioblastoma (GB), mesenchymal stem cells (MSCs) seem to be recruited to the tumor site, where they differentiate into glioblastoma-associated mesenchymal stem/stromal cells (GA-MSCs) under the influence of tumor cells and the TME. GA-MSCs are reported to exert important protumoral functions, such as promoting tumor growth and invasion, increasing angiogenesis, stimulating glioblastoma stem cell (GSC) proliferation and stemness, mediating resistance to therapy and contributing to an immunosuppressive TME. Moreover, they could act as precursor cells for cancer-associated fibroblasts (CAFs), which have recently been identified in GB. In this review, we provide an overview of the different functions exerted by GA-MSCs and CAFs and the current knowledge on the relationship between these cell types. Increasing our understanding of the interactions and signaling pathways in relevant models might contribute to future regimens targeting GA-MSCs and GB-associated CAFs to inhibit tumor growth and render the TME less immunosuppressive.

Aberrant MET Receptor Tyrosine Kinase Signaling in Glioblastoma: Targeted Therapy and Future Directions

Brain tumors represent a heterogeneous group of neoplasms characterized by a high degree of aggressiveness and a poor prognosis. Despite recent therapeutic advances, the treatment of brain tumors, including glioblastoma (GBM), an aggressive primary brain tumor associated with poor prognosis and resistance to therapy, remains a significant challenge. Receptor tyrosine kinases (RTKs) are critical during development and in adulthood. Dysregulation of RTKs through activating mutations and gene amplification contributes to many human cancers and provides attractive therapeutic targets for treatment. Under physiological conditions, the Met RTK, the hepatocyte growth factor/scatter factor (HGF/SF) receptor, promotes fundamental signaling cascades that modulate epithelial-to-mesenchymal transition (EMT) involved in tissue repair and embryogenesis. In cancer, increased Met activity promotes tumor growth and metastasis by providing signals for proliferation, survival, and migration/invasion. Recent clinical genomic studies have unveiled multiple mechanisms by which MET is genetically altered in GBM, including focal amplification, chromosomal rearrangements generating gene fusions, and a splicing variant mutation (exon 14 skipping, METex14del). Notably, MET overexpression contributes to chemotherapy resistance in GBM by promoting the survival of cancer stem-like cells. This is linked to distinctive Met-induced pathways, such as the upregulation of DNA repair mechanisms, which can protect tumor cells from the cytotoxic effects of chemotherapy. The development of MET-targeted therapies represents a major step forward in the treatment of brain tumours. Preclinical studies have shown that MET-targeted therapies (monoclonal antibodies or small molecule inhibitors) can suppress growth and invasion, enhancing the efficacy of conventional therapies. Early-phase clinical trials have demonstrated promising results with MET-targeted therapies in improving overall survival for patients with recurrent GBM. However, challenges remain, including the need for patient stratification, the optimization of treatment regimens, and the identification of mechanisms of resistance. This review aims to highlight the current understanding of mechanisms underlying MET dysregulation in GBM. In addition, it will focus on the ongoing preclinical and clinical assessment of therapies targeting MET dysregulation in GBM.

Image-Based Subtype Classification for Glioblastoma Using Deep Learning: Prognostic Significance and Biologic Relevance

PURPOSE

To apply deep learning algorithms to histopathology images, construct image-based subtypes independent of known clinical and molecular classifications for glioblastoma, and produce novel insights into molecular and immune characteristics of the glioblastoma tumor microenvironment.

MATERIALS AND METHODS

Using whole-slide hematoxylin and eosin images from 214 patients with glioblastoma in The Cancer Genome Atlas (TCGA), a fine-tuned convolutional neural network model extracted deep learning features. Biclustering was used to identify subtypes and image feature modules. Prognostic value of image subtypes was assessed via Cox regression on survival outcomes and validated with 189 samples from the Clinical Proteomic Tumor Analysis Consortium (CPTAC) data set. Morphological, molecular, and immune characteristics of glioblastoma image subtypes were analyzed.

RESULTS

Four distinct subtypes and modules (imClust1-4) were identified for the TCGA patients with glioblastoma on the basis of the image feature data. The glioblastoma image subtypes were significantly associated with overall survival (OS; P = .028) and progression-free survival (P = .003). Apparent association was also observed for disease-specific survival (P = .096). imClust2 had the best prognosis for all three survival end points (eg, after 25 months, imClust2 had >7% surviving patients than the other subtypes). Examination of OS in the external validation using the unseen CPTAC data set showed consistent patterns. Multivariable Cox analyses confirmed that the image subtypes carry unique prognostic information independent of known clinical and molecular predictors. Molecular and immune profiling revealed distinct immune compositions of the tumor microenvironment in different image subtypes and may provide biologic explanations for the patterns in patients' outcomes.

CONCLUSION

Our image-based subtype classification on the basis of deep learning models is a novel tool to refine risk stratification in cancers. The image subtypes detected for glioblastoma represent a promising prognostic biomarker with distinct molecular and immune characteristics and may facilitate developing novel, individualized immunotherapies for glioblastoma.

Eliciting calcium transients with UV nanosecond laser stimulation in adult patient-derived glioblastoma brain cancer cellsin vitro

Objective.Glioblastoma (GBM) is the most common and lethal type of high-grade adult brain cancer. The World Health Organization have classed GBM as an incurable disease because standard treatments have yielded little improvement with life-expectancy being 6-15 months after diagnosis. Different approaches are now crucial to discover new knowledge about GBM communication/function in order to establish alternative therapies for such an aggressive adult brain cancer. Calcium (Ca2+) is a fundamental cell molecular messenger employed in GBM being involved in a wide dynamic range of cellular processes. Understanding how the movement of Ca2+behaves and modulates activity in GBM at the single-cell level is relatively unexplored but holds the potential to yield opportunities for new therapeutic strategies and approaches for cancer treatment.Approach.In this article we establish a spatially and temporally precise method for stimulating Ca2+transients in three patient-derived GBM cell-lines (FPW1, RN1, and RKI1) such that Ca2+communication can be studied from single-cell to larger network scales. We demonstrate that this is possible by administering a single optimized ultra-violet (UV) nanosecond laser pulse to trigger GBM Ca2+transients.Main results.We determine that 1.58µJµm-2is the optimal UV nanosecond laser pulse energy density necessary to elicit a single Ca2+transient in the GBM cell-lines whilst maintaining viability, functionality, the ability to be stimulated many times in an experiment, and to trigger further Ca2+communication in a larger network of GBM cells.Significance.Using adult patient-derived mesenchymal GBM brain cancer cell-lines, the most aggressive form of GBM cancer, this work is the first of its kind as it provides a new effective modality of which to stimulate GBM cells at the single-cell level in an accurate, repeatable, and reliable manner; and is a first step toward Ca2+communication in GBM brain cancer cells and their networks being more effectively studied.

Rewiring of the promoter-enhancer interactome and regulatory landscape in glioblastoma orchestrates gene expression underlying neurogliomal synaptic communication

Chromatin organization controls transcription by modulating 3D-interactions between enhancers and promoters in the nucleus. Alterations in epigenetic states and 3D-chromatin organization result in gene expression changes contributing to cancer. Here, we map the promoter-enhancer interactome and regulatory landscape of glioblastoma, the most aggressive primary brain tumour. Our data reveals profound rewiring of promoter-enhancer interactions, chromatin accessibility and redistribution of histone marks in glioblastoma. This leads to loss of long-range regulatory interactions and overall activation of promoters, which orchestrate changes in the expression of genes associated to glutamatergic synapses, axon guidance, axonogenesis and chromatin remodelling. SMAD3 and PITX1 emerge as major transcription factors controlling genes related to synapse organization and axon guidance. Inhibition of SMAD3 and neuronal activity stimulation cooperate to promote proliferation of glioblastoma cells in co-culture with glutamatergic neurons, and in mice bearing patient-derived xenografts. Our findings provide mechanistic insight into the regulatory networks that mediate neurogliomal synaptic communication.

Rabies virus glycoprotein 29 (RVG29) promotes CAR-T immunotherapy for glioma

Chimeric antigen receptor T cell (CAR-T) therapy has limited efficacy for treating glioma because of the infiltrative nature of the blood-brain barrier (BBB) and T cell exhaustion. Conjugation with rabies virus glycoprotein (RVG) 29 enhances the brain-related efficacy of various agents. Here we assess whether RVG enhances the ability of CAR-T cells to cross the BBB and improves their immunotherapy. We generated 70R CAR-T cells (anti-CD70 CAR-T modified with RVG29) and validated their tumor-killing efficacy in vitro and in vivo. We validated their effects on tumor regression in a human glioma mouse orthotopic xenograft model as well as in patient-derived orthotopic xenograft (PDOX) models. The signaling pathways activated in 70R CAR-T cells were revealed by RNA sequencing. The 70R CAR-T cells we generated showed effective antitumor function against CD70+ glioma cells both in vitro and in vivo. 70R CAR-T cells were better able to cross the BBB into the brain than CD70 CAR-T cells under the same treatment conditions. Moreover, 70R CAR-T cells significantly promote the regression of glioma xenografts and improve the physical characteristics of mice without causing overt adverse effects. RVG modification enables CAR-T cells to cross the BBB, and stimulation with glioma cells induces 70R CAR-T cells to expand in a resting state. The modification of RVG29 has a positive impact on CAR-T therapy for brain tumors and may have potential in CAR-T therapy for glioma.

Characteristics and management of tumor treating fields-related dermatological complications in patients with glioblastoma

Tumor treating fields (TTFields) is a novel approved modality for the treatment of glioblastoma (GBM) exhibiting a satisfactory effect. Although TTFields has shown considerable safety for the normal brain, dermatological adverse events (DAEs) often occur during therapy. However, studies focused on the identification and management of DAEs are rare. The clinical data and photos of skin lesions from 9 patients with GBM were retrospectively analyzed, and the types and grades of individual scalp dermatitis were evaluated based on the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v 5.0). Adherence and safety were also evaluated on the basis of the device monitoring data. Eight patients (88.9%) exhibited grade 1 or grade 2 CTCAE DAEs, all of whom were cured after interventions. The adherence was >90%, with no relevant safety events reported. Finally, a guideline for preventing DAEs in patients with GBM was proposed. The identification and management of TTFields-related DAEs is necessary and urgent in patients with GBM. Timely interventions of DAEs will help to improve the adherence and quality of life of patients, which ultimately improves prognosis. The proposed guideline for preventing DAEs in patients with GBM assists in the management of healthcare providers and may avoid dermatologic complications.

Potassium Ion Channels in Glioma: From Basic Knowledge into Therapeutic Applications

Ion channels, specifically those controlling the flux of potassium across cell membranes, have recently been shown to exhibit an important role in the pathophysiology of glioma, the most common primary central nervous system tumor with a poor prognosis. Potassium channels are grouped into four subfamilies differing by their domain structure, gating mechanisms, and functions. Pertinent literature indicates the vital functions of potassium channels in many aspects of glioma carcinogenesis, including proliferation, migration, and apoptosis. The dysfunction of potassium channels can result in pro-proliferative signals that are highly related to calcium signaling as well. Moreover, this dysfunction can feed into migration and metastasis, most likely by increasing the osmotic pressure of cells allowing the cells to initiate the "escape" and "invasion" of capillaries. Reducing the expression or channel blockage has shown efficacy in reducing the proliferation and infiltration of glioma cells as well as inducing apoptosis, priming several approaches to target potassium channels in gliomas pharmacologically. This review summarizes the current knowledge on potassium channels, their contribution to oncogenic transformations in glioma, and the existing perspectives on utilizing them as potential targets for therapy.

The role of LIN28B in tumor progression and metastasis in solid tumor entities

LIN28B is an RNA-binding protein that targets a broad range of microRNAs and modulates their maturation and activity. Under normal conditions, LIN28B is exclusively expressed in embryogenic stem cells, blocking differentiation and promoting proliferation. In addition, it can play a role in epithelial-to-mesenchymal transition by repressing the biogenesis of let-7 microRNAs. In malignancies, LIN28B is frequently overexpressed, which is associated with increased tumor aggressiveness and metastatic properties. In this review, we discuss the molecular mechanisms of LIN28B in promoting tumor progression and metastasis in solid tumor entities and its potential use as a clinical therapeutic target and biomarker.

Metformin and simvastatin exert additive antitumour effects in glioblastoma via senescence-state: clinical and translational evidence

BACKGROUND

Glioblastoma is one of the most devastating and incurable cancers due to its aggressive behaviour and lack of available therapies, being its overall-survival from diagnosis ∼14-months. Thus, identification of new therapeutic tools is urgently needed. Interestingly, metabolism-related drugs (e.g., metformin/statins) are emerging as efficient antitumour agents for several cancers. Herein, we evaluated the in vitro/in vivo effects of metformin and/or statins on key clinical/functional/molecular/signalling parameters in glioblastoma patients/cells.

METHODS

An exploratory-observational-randomized retrospective glioblastoma patient cohort (n = 85), human glioblastoma/non-tumour brain human cells (cell lines/patient-derived cell cultures), mouse astrocytes progenitor cell cultures, and a preclinical xenograft glioblastoma mouse model were used to measure key functional parameters, signalling-pathways and/or antitumour progression in response to metformin and/or simvastatin.

FINDINGS

Metformin and simvastatin exerted strong antitumour actions in glioblastoma cell cultures (i.e., proliferation/migration/tumoursphere/colony-formation/VEGF-secretion inhibition and apoptosis/senescence induction). Notably, their combination additively altered these functional parameters vs. individual treatments. These actions were mediated by the modulation of key oncogenic signalling-pathways (i.e., AKT/JAK-STAT/NF-κB/TGFβ-pathways). Interestingly, an enrichment analysis uncovered a TGFβ-pathway activation, together with AKT inactivation, in response to metformin + simvastatin combination, which might be linked to an induction of the senescence-state, the associated secretory-phenotype, and to the dysregulation of spliceosome components. Remarkably, the antitumour actions of metformin + simvastatin combination were also observed in vivo [i.e., association with longer overall-survival in human, and reduction in tumour-progression in a mouse model (reduced tumour-size/weight/mitosis-number, and increased apoptosis)].

INTERPRETATION

Altogether, metformin and simvastatin reduce aggressiveness features in glioblastomas, being this effect significantly more effective (in vitro/in vivo) when both drugs are combined, offering a clinically relevant opportunity that should be tested for their use in humans.

FUNDING

Spanish Ministry of Science, Innovation and Universities; Junta de Andalucía; CIBERobn (CIBER is an initiative of Instituto de Salud Carlos III, Spanish Ministry of Health, Social Services and Equality).

Rilotumumab Resistance Acquired by Intracrine Hepatocyte Growth Factor Signaling

Drug resistance is a long-standing impediment to effective systemic cancer therapy and acquired drug resistance is a growing problem for molecularly-targeted therapeutics that otherwise have shown unprecedented successes in disease control. The hepatocyte growth factor (HGF)/Met receptor pathway signaling is frequently involved in cancer and has been a subject of targeted drug development for nearly 30 years. To anticipate and study specific resistance mechanisms associated with targeting this pathway, we engineered resistance to the HGF-neutralizing antibody rilotumumab in glioblastoma cells harboring autocrine HGF/Met signaling, a frequent abnormality of this brain cancer in humans. We found that rilotumumab resistance was acquired through an unusual mechanism comprising dramatic HGF overproduction and misfolding, endoplasmic reticulum (ER) stress-response signaling and redirected vesicular trafficking that effectively sequestered rilotumumab and misfolded HGF from native HGF and activated Met. Amplification of MET and HGF genes, with evidence of rapidly acquired intron-less, reverse-transcribed copies in DNA, was also observed. These changes enabled persistent Met pathway activation and improved cell survival under stress conditions. Point mutations in the HGF pathway or other complementary or downstream growth regulatory cascades that are frequently associated with targeted drug resistance in other prevalent cancer types were not observed. Although resistant cells were significantly more malignant, they retained sensitivity to Met kinase inhibition and acquired sensitivity to inhibition of ER stress signaling and cholesterol biosynthesis. Defining this mechanism reveals details of a rapidly acquired yet highly-orchestrated multisystem route of resistance to a selective molecularly-targeted agent and suggests strategies for early detection and effective intervention.

Current perspectives on diffuse midline glioma and a different role for the immune microenvironment compared to glioblastoma

Diffuse midline glioma (DMG), formerly called diffuse intrinsic pontine glioma (DIPG), is a high-grade malignant pediatric brain tumor with a near-zero survival rate. To date, only radiation therapy provides marginal survival benefit; however, the median survival time remains less than a year. Historically, the infiltrative nature and sensitive location of the tumor rendered surgical removal and biopsies difficult and subsequently resulted in limited knowledge of the disease, as only post-mortem tissue was available. Therefore, clinical decision-making was based upon experience with the more frequent and histologically similar adult glioblastoma (GBM). Recent advances in tissue acquisition and molecular profiling revealed that DMG and GBM are distinct disease entities, with separate tissue characteristics and genetic profiles. DMG is characterized by heterogeneous tumor tissue often paired with an intact blood–brain barrier, possibly explaining its resistance to chemotherapy. Additional profiling shed a light on the origin of the disease and the influence of several mutations such as a highly recurring K27M mutation in histone H3 on its tumorigenesis. Furthermore, early evidence suggests that DMG has a unique immune microenvironment, characterized by low levels of immune cell infiltration, inflammation, and immunosuppression that may impact disease development and outcome. Within the tumor microenvironment of GBM, tumor-associated microglia/macrophages (TAMs) play a large role in tumor development. Interestingly, TAMs in DMG display distinct features and have low immune activation in comparison to other pediatric gliomas. Although TAMs have been investigated substantially in GBM over the last years, this has not been the case for DMG due to the lack of tissue for research. Bit by bit, studies are exploring the TAM–glioma crosstalk to identify what factors within the DMG microenvironment play a role in the recruitment and polarization of TAMs. Although more research into the immune microenvironment is warranted, there is evidence that targeting or stimulating TAMs and their factors provide a potential treatment option for DMG. In this review, we provide insight into the current status of DMG research, assess the knowledge of the immune microenvironment in DMG and GBM, and present recent findings and therapeutic opportunities surrounding the TAM–glioma crosstalk.

Potassium Ion Channels in Malignant Central Nervous System Cancers

Malignant central nervous system (CNS) cancers are among the most difficult to treat, with low rates of survival and a high likelihood of recurrence. This is primarily due to their location within the CNS, hindering adequate drug delivery and tumour access via surgery. Furthermore, CNS cancer cells are highly plastic, an adaptive property that enables them to bypass targeted treatment strategies and develop drug resistance. Potassium ion channels have long been implicated in the progression of many cancers due to their integral role in several hallmarks of the disease. Here, we will explore this relationship further, with a focus on malignant CNS cancers, including high-grade glioma (HGG). HGG is the most lethal form of primary brain tumour in adults, with the majority of patient mortality attributed to drug-resistant secondary tumours. Hence, targeting proteins that are integral to cellular plasticity could reduce tumour recurrence, improving survival. This review summarises the role of potassium ion channels in malignant CNS cancers, specifically how they contribute to proliferation, invasion, metastasis, angiogenesis, and plasticity. We will also explore how specific modulation of these proteins may provide a novel way to overcome drug resistance and improve patient outcomes.

Neurotransmitters: Potential Targets in Glioblastoma

Simple Summary

Aiming to discover potential treatments for GBM, this review connects emerging research on the roles of neurotransmitters in the normal neural and the GBM microenvironments and sheds light on the prospects of their application in the neuropharmacology of GBM. Conventional therapy is blamed for its poor effect, especially in inhibiting tumor recurrence and invasion. Facing this dilemma, we focus on neurotransmitters that modulate GBM initiation, progression and invasion, hoping to provide novel therapy targeting GBM. By analyzing research concerning GBM therapy systematically and scientifically, we discover increasing insights into the regulatory effects of neurotransmitters, some of which have already shown great potential in research in vivo or in vitro. After that, we further summarize the potential drugs in correlation with previously published research. In summary, it is worth expecting that targeting neurotransmitters could be a promising novel pharmacological approach for GBM treatment.

Abstract

For decades, glioblastoma multiforme (GBM), a type of the most lethal brain tumor, has remained a formidable challenge in terms of its treatment. Recently, many novel discoveries have underlined the regulatory roles of neurotransmitters in the microenvironment both physiologically and pathologically. By targeting the receptors synaptically or non-synaptically, neurotransmitters activate multiple signaling pathways. Significantly, many ligands acting on neurotransmitter receptors have shown great potential for inhibiting GBM growth and development, requiring further research. Here, we provide an overview of the most novel advances concerning the role of neurotransmitters in the normal neural and the GBM microenvironments, and discuss potential targeted drugs used for GBM treatment.

Contribution of the Testosterone Androgen Receptor–PARD3B Signaling Axis to Tumorigenesis and Malignance of Glioblastoma Multiforme through Stimulating Cell Proliferation and Colony Formation

Background: Glioblastoma multiforme (GBM) is the most common and malignant brain tumor with very poor prognoses. After surgical resection of the primary tumor, rapid proliferation of residual glioblastoma cells is a critical cause explaining tumor malignance and recurrence. In this study, we evaluated de novo roles of the testosterone androgen receptor (AR)–PARD3B signaling axis in the tumorigenesis and malignance of human GBM and the possible related mechanisms. Methods: AR and PARD3B gene expressions and their correlations were mined from The Cancer Genome Atlas (TCGA) database and analyzed using the UALCAN system. Analyses using a real-time PCR, cell proliferation, and colony formation and a loss-of-function strategy by suppressing AR activity with its specific inhibitor, enzalutamide, were then carried out to determine roles of the testosterone AR–PARD3B signaling axis in tumor malignance. Results: Expressions of AR, PARD3B mRNA, and proteins in human GBM tissues were upregulated compared to normal human brain tissues. In contrast, levels of AR and PARD3B mRNA in most TCGA pan-cancer types were downregulated compared to their respective normal tissues. Interestingly, a highly positive correlation between AR and PARD3B gene expressions in human GBM was identified. The results of a bioinformatics search further showed that there were five AR-specific DNA-binding elements predicted in the 5′ promoter of the PARD3B gene. Regarding the mechanisms, exposure of human glioblastoma cells to testosterone induced AR and PARD3B gene expressions and successively stimulated cell proliferation and colony formation. Suppressing AR activity concurrently resulted in significant attenuations of testosterone-induced PARD3B gene expression, cell proliferation, and colony formation in human glioblastoma cells. Conclusions: This study showed the contribution of the testosterone AR–PARD3B signaling axis to the tumorigenesis and malignance of human GBM through stimulating cell proliferation and colony formation. Therefore, the AR-PARD3B signaling axis could be targeted for potential therapy for human GBM.

Molecular Signature of Astrocytes for Gene Delivery by the Synthetic Adeno-Associated Viral Vector rAAV9P1

Astrocytes have crucial functions in the central nervous system (CNS) and are major players in many CNS diseases. Research on astrocyte-centered diseases requires efficient and well-characterized gene transfer vectors. Vectors derived from the Adeno-associated virus serotype 9 (AAV9) target astrocytes in the brains of rodents and nonhuman primates. A recombinant (r) synthetic peptide-displaying AAV9 variant, rAAV9P1, that efficiently and selectively transduces cultured human astrocytes, has been described previously. Here, it is shown that rAAV9P1 retains astrocyte-targeting properties upon intravenous injection in mice. Detailed analysis of putative receptors on human astrocytes shows that rAAV9P1 utilizes integrin subunits αv, β8, and either β3 or β5 as well as the AAV receptor AAVR. This receptor pattern is distinct from that of vectors derived from wildtype AAV2 or AAV9. Furthermore, a CRISPR/Cas9 genome-wide knockout screening revealed the involvement of several astrocyte-associated intracellular signaling pathways in the transduction of human astrocytes by rAAV9P1. This study delineates the unique receptor and intracellular pathway signatures utilized by rAAV9P1 for targeting human astrocytes. These results enhance the understanding of the transduction biology of synthetic rAAV vectors for astrocytes and can promote the development of advanced astrocyte-selective gene delivery vehicles for research and clinical applications.

Active Immunotherapy for Glioblastoma Treatment: A Systematic Review and Meta-Analysis

INTRODUCTION

Glioblastoma multiforme (GBM) makes 60-70% of gliomas and 15% of primary brain tumors. Despite the availability of standard multimodal therapy, 2 years, 3 years, and 5 years survival rate of GBM are still low. Active immunotherapy is a relatively new treatment option for GBM that seems promising.

METHODS

An electronic database search on PubMed, Cochrane, Scopus, and clinicaltrials.gov was performed to include all relevant studies. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Reported parameters are OS, PFS, AEs, post treatment KPS, and 2 year mortality.

RESULTS

Active immunotherapy provided better OS (HR = .85; 95% CI = .71-1.01; P = .06) and PFS (HS = .83; 95% CI= .66 - 1.03; P = .11) side albeit not statistically significant. Active immunotherapy reduces the risk of 2 year mortality as much as 2.5% compared to control group (NNT and RRR was 56.7078 and 0,0258, respectively).

CONCLUSION

Active immunotherapy might be beneficial in terms of survival rate in patients with GBM although not statistically significant. It could be a treatment option for GBM in the future.

Immunotherapy for glioblastoma: the promise of combination strategies

Glioblastoma (GBM) treatment has remained almost unchanged for more than 20 years. The current standard of care involves surgical resection (if possible) followed by concomitant radiotherapy and chemotherapy. In recent years, immunotherapy strategies have revolutionized the treatment of many cancers, increasing the hope for GBM therapy. However, mostly due to the high, multifactorial immunosuppression occurring in the microenvironment, the poor knowledge of the neuroimmune system and the presence of the blood-brain barrier, the efficacy of immunotherapy in GBM is still low. Recently, new strategies for GBM treatments have employed immunotherapy combinations and have provided encouraging results in both preclinical and clinical studies. The lessons learned from clinical trials highlight the importance of tackling different arms of immunity. In this review, we aim to summarize the preclinical evidence regarding combination immunotherapy in terms of immune and survival benefits for GBM management. The outcomes of recent studies assessing the combination of different classes of immunotherapeutic agents (e.g., immune checkpoint blockade and vaccines) will be discussed. Finally, future strategies to ameliorate the efficacy of immunotherapy and facilitate clinical translation will be provided to address the unmet medical needs of GBM.

Adenosinergic Signaling as a Key Modulator of the Glioma Microenvironment and Reactive Astrocytes

Astrocytes are numerous glial cells of the central nervous system (CNS) and play important roles in brain homeostasis. These cells can directly communicate with neurons by releasing gliotransmitters, such as adenosine triphosphate (ATP) and glutamate, into the multipartite synapse. Moreover, astrocytes respond to tissue injury in the CNS environment. Recently, astrocytic heterogeneity and plasticity have been discussed by several authors, with studies proposing a spectrum of astrocytic activation characterized by A1/neurotoxic and A2/neuroprotective polarization extremes. The fundamental roles of astrocytes in communicating with other cells and sustaining homeostasis are regulated by purinergic signaling. In the CNS environment, the gliotransmitter ATP acts cooperatively with other glial signaling molecules, such as cytokines, which may impact CNS functions by facilitating/inhibiting neurotransmitter release. Adenosine (ADO), the main product of extracellular ATP metabolism, is an important homeostatic modulator and acts as a neuromodulator in synaptic transmission via P1 receptor sensitization. Furthermore, purinergic signaling is a key factor in the tumor microenvironment (TME), as damaged cells release ATP, leading to ADO accumulation in the TME through the ectonucleotidase cascade. Indeed, the enzyme CD73, which converts AMP to ADO, is overexpressed in glioblastoma cells; this upregulation is associated with tumor aggressiveness. Because of the crucial activity of CD73 in these cells, extracellular ADO accumulation in the TME contributes to sustaining glioblastoma immune escape while promoting A2-like activation. The present review describes the importance of ADO in modulating astrocyte polarization and simultaneously promoting tumor growth. We also discuss whether targeting of CD73 to block ADO production can be used as an alternative cancer therapy.

Neuroimmunomodulatory Properties of Flavonoids and Derivates: A Potential Action as Adjuvants for the Treatment of Glioblastoma

Glioblastomas (GBMs) are tumors that have a high ability to migrate, invade and proliferate in the healthy tissue, what greatly impairs their treatment. These characteristics are associated with the complex microenvironment, formed by the perivascular niche, which is also composed of several stromal cells including astrocytes, microglia, fibroblasts, pericytes and endothelial cells, supporting tumor progression. Further microglia and macrophages associated with GBMs infiltrate the tumor. These innate immune cells are meant to participate in tumor surveillance and eradication, but they become compromised by GBM cells and exploited in the process. In this review we discuss the context of the GBM microenvironment together with the actions of flavonoids, which have attracted scientific attention due to their pharmacological properties as possible anti-tumor agents. Flavonoids act on a variety of signaling pathways, counteracting the invasion process. Luteolin and rutin inhibit NFκB activation, reducing IL-6 production. Fisetin promotes tumor apoptosis, while inhibiting ADAM expression, reducing invasion. Naringenin reduces tumor invasion by down-regulating metalloproteinases expression. Apigenin and rutin induce apoptosis in C6 cells increasing TNFα, while decreasing IL-10 production, denoting a shift from the immunosuppressive Th2 to the Th1 profile. Overall, flavonoids should be further exploited for glioma therapy.

Feasibility of Photodynamic Therapy for Glioblastoma with the Mitochondria-Targeted Photosensitizer Tetramethylrhodamine Methyl Ester (TMRM)

One of the most challenging problems in the treatment of glioblastoma (GBM) is the highly infiltrative nature of the disease. Infiltrating cells that are non-resectable are left behind after debulking surgeries and become a source of regrowth and recurrence. To prevent tumor recurrence and increase patient survival, it is necessary to cleanse the adjacent tissue from GBM infiltrates. This requires an innovative local approach. One such approach is that of photodynamic therapy (PDT) which uses specific light-sensitizing agents called photosensitizers. Here, we show that tetramethylrhodamine methyl ester (TMRM), which has been used to asses mitochondrial potential, can be used as a photosensitizer to target GBM cells. Primary patient-derived GBM cell lines were used, including those specifically isolated from the infiltrative edge. PDT with TMRM using low-intensity green light induced mitochondrial damage, an irreversible drop in mitochondrial membrane potential and led to GBM cell death. Moreover, delayed photoactivation after TMRM loading selectively killed GBM cells but not cultured rat astrocytes. The efficacy of TMRM-PDT in certain GBM cell lines may be potentiated by adenylate cyclase activator NKH477. Together, these findings identify TMRM as a prototypical mitochondrially targeted photosensitizer with beneficial features which may be suitable for preclinical and clinical translation.