The Interplay between Glioblastoma and Its Microenvironment

Degradation fragments of Tau and type IV collagen as serum biomarkers in patients with recurrent glioblastoma treated with nivolumab and bevacizumab

PURPOSE

There is an unmet need for new treatment options and biomarkers for patients with glioblastoma (GBM). Here we investigated three non-invasive biomarkers: type VI collagen degraded by granzyme B (C4G) and matrix metalloproteases (C4M), respectively, and ADAM10-degraded Tau (Tau-A).

METHODS

Biomarker levels in pre- and on-treatment serum samples from patients with recurrent GBM (n = 39) treated with nivolumab and bevacizumab (NCT03890952) were compared to healthy levels (n = 22) and associated with overall survival (OS) outcome (median cutpoint). Longitudinal changes in biomarkers were investigated by a Mixed-effects analysis.

RESULTS

Tau-A (p < 0.0001) and C4G (p = 0.005), but not C4M (p = 0.106), were increased in patients. High Tau-A and C4G associated with improved OS (Tau-A: HR = 0.41, 95%CI = 0.20-0.86, C4G: HR = 0.47, 95%CI = 0.24-0.94). Only C4G increased with treatment (p = 0.024-0.005).

CONCLUSIONS

Tau-A and C4G are elevated in serum from patients with recurrent GBM and prognostic for OS. If validated, these biomarkers could be applied to clinical trials.

Black phosphorus nanosheets activate tumor immunity of glioblastoma by modulating the expression of the immunosuppressive molecule PD-L1

The tumor microenvironment in glioblastoma (GBM) is characterized by a pronounced immunosuppressive state, which significantly hampers tumor treatment and contributes to treatment resistance. While our previous research established that black phosphorus nanosheets (BPNS) inhibited glioblastoma cell migration and invasion, the impact of BPNS on the anti-tumor-associated immune mechanism remains unexplored. This study firstly investigated whether BPNS could modulate the tumor microenvironment through immunotherapy and elucidated the underlying mechanisms. We used a subcutaneous mouse model of GBM, which evaded immune surveillance to evaluate BPNS effects on immune cells within the tumor microenvironment. Our results demonstrated that BPNS significantly enhanced the tumor-suppressive microenvironment, reactivating immune cells' cytotoxicity against tumor cells. Moreover, further analysis revealed that BPNS counteracted the immunosuppressive state by reducing the expression of the immunosuppressive molecule PD-L1 in tumor cells, leading to an anti-tumor effect. Mechanistically, BPNS reduced PD-L1 expression through two main pathways: by inducing autophagy via binding to the HSP90 protein, leading to PD-L1 degradation through the autophagy pathway, and by inhibiting the PI3K-AKT signaling pathway, which reduced PD-L1 mRNA levels. This study expands the understanding of BPNS biological activity and suggests new strategies for utilizing BPNS as an adjuvant in immunotherapy.

Insights of immune cell heterogeneity, tumor-initiated subtype transformation, drug resistance, treatment and detecting technologies in glioma microenvironment

BACKGROUND

With the gradual understanding of glioma development and the immune microenvironment, many immune cells have been discovered. Despite the growing comprehension of immune cell functions and the clinical application of immunotherapy, the precise roles and characteristics of immune cell subtypes, how glioma induces subtype transformation of immune cells and its impact on glioma progression have yet to be understood.

AIM OF THE REVIEW

In this review, we comprehensively center on the four major immune cells within the glioma microenvironment, particularly neutrophils, macrophages, lymphocytes, myeloid-derived suppressor cells (MDSCs), and other significant immune cells. We discuss (1) immune cell subtype markers, (2) glioma-induced immune cell subtype transformation, (3) the mechanisms of each subtype influencing chemotherapy resistance, (4) therapies targeting immune cells, and (5) immune cell-associated single-cell sequencing. Eventually, we identified the characteristics of immune cell subtypes in glioma, comprehensively summarized the exact mechanism of glioma-induced immune cell subtype transformation, and concluded the progress of single-cell sequencing in exploring immune cell subtypes in glioma.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In conclusion, we have analyzed the mechanism of chemotherapy resistance detailly, and have discovered prospective immunotherapy targets, excavating the potential of novel immunotherapies approach that synergistically combines radiotherapy, chemotherapy, and surgery, thereby paving the way for improved immunotherapeutic strategies against glioma and enhanced patient outcomes.

Stress-induced pro-inflammatory glioblastoma stem cells secrete TNFAIP6 to enhance tumor growth and induce suppressive macrophages

Glioblastoma (GBM) is the most aggressive primary intracranial tumor, with glioblastoma stem cells (GSCs) enforcing the intratumoral hierarchy. The inflammatory microenvironment influences tumor development at varying stages, while the underlying mechanism of GSCs facing pro-inflammatory stress remains unclear. Here, we show that, in human GBM, pro-inflammatory stress from pro-inflammatory macrophages (pTAMs) maintains GSC proliferation and self-renewal. Tumor necrosis factor alpha-induced protein 6 (TNFAIP6), as a responder in patient-derived GSCs to pro-inflammatory stress tumor necrosis factor alpha (TNF-α) from human pTAMs, promotes tumor growth through binding epidermal growth factor (EGF) and prolonging EGF receptor (EGFR)-phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT) signaling activation. Meanwhile, pro-inflammatory stress-induced patient-derived GSCs secrete TNFAIP6 to transform macrophage phenotype from pTAMs to inflammatory-suppressive macrophages (sTAMs). Collectively, pharmacological or genetic disruption of TNFAIP6 autocrine and paracrine communication between patient-derived GSCs and TAMs inhibited GSC proliferation and self-renewal in vitro and in patient-derived xenograft tumor-bearing mice, suggesting that TNFAIP6 is an effective target for GBM therapy.

Exploring tumor-associated macrophages in glioblastoma: from diversity to therapy

Glioblastoma is the most aggressive and lethal cancer of the central nervous system, presenting substantial treatment challenges. The current standard treatment, which includes surgical resection followed by temozolomide and radiation, offers limited success. While immunotherapies, such as immune checkpoint inhibitors, have proven effective in other cancers, they have not demonstrated significant efficacy in GBM. Emerging research highlights the pivotal role of tumor-associated macrophages (TAMs) in supporting tumor growth, fostering treatment resistance, and shaping an immunosuppressive microenvironment. Preclinical studies show promising results for therapies targeting TAMs, suggesting potential in overcoming these barriers. TAMs consist of brain-resident microglia and bone marrow-derived macrophages, both exhibiting diverse phenotypes and functions within the tumor microenvironment. This review delves into the origin, heterogeneity, and functional roles of TAMs in GBM, underscoring their dual roles in tumor promotion and suppression. It also summarizes recent progress in TAM-targeted therapies, which may, in combination with other treatments like immunotherapy, pave the way for more effective and personalized strategies against this aggressive malignancy.

Tumor-infiltrating and circulating B cells mediate local and systemic immunomodulatory mechanisms in Glioblastoma

BACKGROUND

Glioblastoma (GBM) demonstrates extensive immunomodulatory mechanisms that challenge effective therapeutic interventions. These phenomena extend well beyond the tumor microenvironment (TME) and are reflected in the circulating immunophenotype. B lymphocytes (B cells) have received limited attention in GBM studies despite their emerging importance in mediating both local and systemic immune responses. Recent findings highlight the complex regulatory interactions between B cells and other immune cell populations, including tumor-infiltrating macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and other infiltrating lymphocytes (TILs). B cells are believed to hinder the efficacy of modern immunotherapy strategies focusing on T cells.

METHODS

This is a focused review of available evidence regarding B cells in GBM through January 2025.

RESULTS

Peripheral blood reflects a systemically dampened immune response, with sustained lymphopenia, increased plasma cells, and dysfunctional memory B cells. The tumor immune landscape is enriched in cells of B-lineage. Subsets of poorly characterized B regulatory cells (Bregs) populate the TME, developing their phenotype due to their proximity to MDSCs, TAMs, and tumoral cells. The Bregs inhibit CD8+ T activity and may have potential prognostic significance.

CONCLUSION

Understanding the role of B cells, how they are recruited, and their differentiation shifted towards an immunomodulatory role could inform better therapeutic strategies and unleash their full antitumoral potential in GBM.

Fusion of glioma-associated mesenchymal stem/stromal cells with glioma cells promotes macrophage recruitment and M2 polarization via m6A modification of CSF1

Malignant glioma is the most common primary malignant tumor of the brain in adults, with glioblastoma (GBM) being the most aggressive subtype. Mesenchymal stem/stromal cells (MSCs) have been shown to fuse with tumor cells in various cancers including glioma, thereby regulating tumor progression. However, there has been no systematic research on the fusion of glioma-associated MSCs (GA-MSCs) with glioma cells. Here, it is shown that GA-MSCs are able to spontaneously fuse with glioma cells both in vitro and in vivo. The hybrid cells display significantly lower levels of N6-methyladenosine (m6A) modification and can modulate the glioma microenvironment by attracting and inducing M2-like polarization of macrophages. Mechanistically, the demethylase fat mass and obesity-associated protein (FTO) mediates demethylation in hybrids and promotes macrophage colony-stimulating factor (CSF1) secretion by increasing its RNA stability in an m6A-YTH domain family 2 (YTHDF2)-dependent manner. Our study reveals a novel crosstalk mechanism between glioma cells, GA-MSCs, and macrophages in glioma microenvironment, offering potential new approaches for glioma therapy.

The alternatively spliced diacylglycerol kinase gamma-Δ exon13 transcript generated under hypoxia promotes glioblastoma progression

Background

Glioblastoma (GBM) is one of the most malignant types of central nervous system tumors. Oxygen deprivation in the tumor microenvironment is thought to be an important factor in promoting GBM progression. However, the mechanisms of hypoxia-promoted tumor progression remain elusive.

Methods

Alternative splicing of diacylglycerol kinase gamma (DGKG)-Δ exon13 was amplified and verified by PCR-Sanger sequencing. The functions of DGKG and DGKG-Δ exon13 were analyzed by Cell counting kit-8 (CCK-8), Transwell, Matrigel-transwell experiments, and in vivo orthotropic GBM animal models. Transcriptome analyses were done to find out the regulated genes.

Results

In this study, we found that a new transcript DGKG-Δ exon13 was generated in GBM under hypoxia via alternative splicing. Moreover, the results of CCK-8, Transwell, and Matrigel-transwell experiments showed that the proliferation, migration, and invasion abilities of U87-MG and T98G were decreased after DGKG knockdown. Compared to wild-type DGKG, DGKG-Δ exon13 overexpression significantly promoted cellular proliferation, migration, and invasion abilities in GBM. Furthermore, in vivo, orthotropic GBM animal models analysis showed that the tumor volumes were much smaller in the DGKG knockdown group. However, the tumor sizes in the DGKG and DGKG-Δ exon13 rescue groups were restored, especially in the DGKG-Δ exon13 group. Transcriptome analysis revealed that MORC1, KLHDC7B, ATP1A2, INHBE, TMEM119, and FGD3 were altered significantly when DGKG was knocked down. IL-16, CCN2, and EFNB3 were specifically regulated by DGKG-Δ exon13.

Conclusions

Our study found that hypoxia-induced alternative splicing transcript DGKG-Δ exon13 promotes GBM proliferation and infiltration, which might provide a new potential target for the clinical treatment and diagnosis of GBM.

Large-scale bulk and single-cell RNA sequencing combined with machine learning reveals glioblastoma-associated neutrophil heterogeneity and establishes a VEGFA+ neutrophil prognostic model

BACKGROUND

Neutrophils play a key role in the tumor microenvironment (TME); however, their functions in glioblastoma (GBM) are overlooked and insufficiently studied. A detailed analysis of GBM-associated neutrophil (GBMAN) subpopulations may offer new insights and opportunities for GBM immunotherapy.

METHODS

We analyzed single-cell RNA sequencing (scRNA-seq) data from 127 isocitrate dehydrogenase (IDH) wild-type GBM samples to characterize the GBMAN subgroups, emphasizing developmental trajectories, cellular communication, and transcriptional networks. We implemented 117 machine learning combinations to develop a novel risk model and compared its performance to existing glioma models. Furthermore, we assessed the biological and molecular features of the GBMAN subgroups in patients.

RESULTS

From integrated large-scale scRNA-seq data (498,747 cells), we identified 5,032 neutrophils and classified them into four distinct subtypes. VEGFA+GBMAN exhibited reduced inflammatory response characteristics and a tendency to interact with stromal cells. Furthermore, these subpopulations exhibited significant differences in transcriptional regulation. We also developed a risk model termed the "VEGFA+neutrophil-related signature" (VNRS) using machine learning methods. The VNRS model showed higher accuracy than previously published risk models and was an independent prognostic factor. Additionally, we observed significant differences in immunotherapy responses, TME interactions, and chemotherapy efficacy between high-risk and low-risk VNRS score groups.

CONCLUSION

Our study highlights the critical role of neutrophils in the TME of GBM, allowing for a better understanding of the composition and characteristics of GBMAN. The developed VNRS model serves as an effective tool for evaluating the risk and guiding clinical treatment strategies for GBM.

CLINICAL TRIAL NUMBER

Not applicable.

Challenges and Emerging Strategies of Immunotherapy for Glioblastoma

Glioblastoma (GBM) is recognized as the most lethal primary malignant tumor of the central nervous system. Although traditional treatments can somewhat prolong patient survival, the overall prognosis remains grim. Immunotherapy has become an effective method for GBM treatment. Oncolytic virus, checkpoint inhibitors, CAR T cells and tumor vaccines have all been applied in this field. Moreover, the combining of immunotherapy with traditional radiotherapy, chemotherapy, or gene therapy can further improve the treatment outcome. This review systematically summarizes the features of GBM, the recent progress of immunotherapy in overcoming GBM.

Migration of Regulatory T Cells to the Peritumor Microenvironment of Experimental Glioblastoma

Glioblastoma is the most aggressive primary brain tumor with poor prognosis characterized by resistance to standard treatments and immune evasion. Regulatory T lymphocytes (Tregs) play a key role in immune suppression in the tumor microenvironment and can be used as targets for malignant gliomas therapy. The aim of the investigation is to study migration of Tregs to the tumor site in the process of dynamic glioblastoma growth on the transgenic C57Bl/6-FoxP3-eGFP mouse line.

Materials and Methods

The study was performed using the C57Bl/6-FoxP3-eGFP mouse strain, which allows for the detection of FoxP3-positive Tregs by fluorescent signal. Orthotopic glioblastomas were implanted by stereotactic injection of fluorescently labeled GL-261-BFP and GL-261-mScarlet tumor cell lines. Intravital confocal microscopy was used to monitor infiltration of the tumor site by immune cells, visualized by intravenous injection of fluorescently labeled antibodies against CD45. The results of intravital microscopy were confirmed by histological and immunohistochemical examination on days 3, 6, 9, 14, and 16 after the implantation. To assess the immunological status, tumor-infiltrating lymphocytes (TILs) were isolated from the brain and Tregs were counted using a flow cytometer (immediately after isolation and after cultivation for 2 weeks).

Results

Intravital microscopy and brain slice studies have demonstrated infiltration of the glioblastoma site by Tregs, with the proportion of Tregs increasing with tumor progression (the increase in the absolute number of Treg was proportional to the increase in the number of glioma cells). Subsequent co-cultivation of isolated TILs with glioma cells revealed increase of Treg population within 2 weeks from 2.8% to >40%, confirming the activating effect of glioblastoma with respect to Tregs.

Conclusion

The dynamics of GL-261 glioma microenvironment infiltration by Tregs has been investigated. The glioblastoma cells were shown to activate Tregs in the peritumor space in vivo and to promote their selective expansion when co-cultured with TILs in vitro. These data can be used for further studies on C57Bl/6-FoxP3-eGFP mice to find approaches to inactivate Tregs in glioblastoma.

EFNB1 drives glioma progression and shapes the immune microenvironment: a potential prognostic biomarker

Gliomas, a heterogeneous group of tumors affecting the brain and spinal cord, present a significant clinical challenge. Ephrin B1 (EFNB1) has been implicated in various malignancies. However, its role in gliomas remained poorly understood. Hence, this study aimed to elucidate the connection between EFNB1 and the progression of glioma. A retrospective RNA-seq analysis was conducted by utilizing the data from glioma patients in the TCGA and CGGA databases. Kaplan-Meier survival analysis and multivariate regression models were employed to evaluate the prognostic significance of EFNB1. RT-PCR was used to quantify EFNB1 expression in glioma tissues and cell lines. Meanwhile, in vitro assays were carried out to assess its functional roles in glioma cells. Our findings demonstrated that EFNB1 expression was significantly elevated in gliomas and other cancers. Moreover, high EFNB1 expression was closely correlated with advanced clinical stages and poor prognosis. Notably, multivariate analysis identified EFNB1 as an independent prognostic factor for overall survival. KEGG pathway analysis suggested that EFNB1 was involved in critical biological processes, including the cell cycle, protein processing in the endoplasmic reticulum, Epstein-Barr virus infection, and Salmonella infection. Furthermore, EFNB1 expression was associated with immune cell infiltration, particularly Th2 cells, macrophages, and plasmacytoid dendritic cells. In glioma cells, EFNB1 expression was markedly increased. Consequently, functional experiments demonstrated that EFNB1 knockdown inhibited glioma cell proliferation, invasion, and migration. These results highlighted EFNB1 as a novel independent prognostic biomarker and suggest its potential role in shaping the immunological microenvironment of gliomas.

Targeting metabolic reprogramming in glioblastoma as a new strategy to overcome therapy resistance

Glioblastoma (GBM) is one of the deadliest tumors due to its high aggressiveness and resistance to standard therapies, resulting in a dismal prognosis. This lethal tumor carries out metabolic reprogramming in order to modulate specific pathways, providing metabolites that promote GBM cells proliferation and limit the efficacy of standard treatments. Indeed, GBM remodels glucose metabolism and undergoes Warburg effect, fuelling glycolysis even when oxygen is available. Moreover, recent evidence revealed a rewiring in nucleotide, lipid and iron metabolism, resulting not only in an increased tumor growth, but also in radio- and chemo-resistance. Thus, while on the one hand metabolic reprogramming is an advantage for GBM, on the other hand it may represent an exploitable target to hamper GBM progression. Lately, a number of studies focused on drugs targeting metabolism to uncover their effects on tumor proliferation and therapy resistance, demonstrating that some of these are effective, in combination with conventional treatments, sensitizing GBM to radiotherapy and chemotherapy. However, GBM heterogeneity could lead to a plethora of metabolic alterations among subtypes, hence a metabolic treatment might be effective for proneural tumors but not for mesenchymal ones, which are more aggressive and resistant to conventional approaches. This review explores key mechanisms of GBM metabolic reprogramming and their involvement in therapy resistance, highlighting how metabolism acts as a double-edged sword for GBM, taking into account metabolic pathways that seem to offer promising treatment options for GBM.

Glioblastoma progression is hindered by melatonin-primed mesenchymal stromal cells through dynamic intracellular and extracellular reorganizations

Rationale: Glioblastoma (GBM) is the most fatal form of brain cancer and its treatment represents a persistent challenge. Mesenchymal stromal cells (MSCs) have been explored as therapeutic tools in cancer management owing to their tumor-homing abilities. However, their clinical application is limited due to the controversial role of MSCs in carcinogenesis. This study investigates how MSCs influence tumor behavior and explores the synergistic anticancer effects in combination with melatonin (Mel). Methods: Orthotopic and subcutaneous GBM xenograft mouse models were used to assess the antitumor effect of Mel pre-treated MSCs (MSCMel). Histological, immunohistochemical, and ultrastructural analyses were conducted to identify phenotypic changes in tumors. Through a set of in vitro assays, including direct and indirect co-cultures, dynamic single-cell tracking and tumorsphere assay, we explored the impact of MSCMel on primary and non-primary GBM cells. Transcriptomic profiling was used to identify genes and pathways modulated by this synergistic therapy. Results: MSCMel delayed tumor growth in mice and increased collagen deposition. Additionally, MSCMel showed enhanced capacity to prevent GBM cell migration compared to untreated MSCs. Molecular analysis identified genes and proteins related to cell migration, cytoskeletal dynamics and extracellular matrix remodeling in GBM cells exposed to MSCMel, including reduced vimentin expression. Finally, a genetic signature associated with the clinical outcomes of GBM patients was identified. Conclusions: Our study demonstrates that melatonin enhances the anticancer properties of MSCs, providing new insights into their interaction with GBM cells and tumor environment. These findings offer valuable guidance for advancing MSC-based therapies in clinical practice.

HSPA5-mediated glioma hypoxia tolerance promotes M2 macrophage polarization under hypoxic microenvironment

BACKGROUND

The tumor microenvironment (TME), with hallmark features of hypoxia and immunosuppression, plays a crucial role in the progression of various solid tumors. However, the intricate interplay between tumor hypoxia and the formation of tumor immune microenvironment in glioma remains incompletely understood.

METHODS

In the present study, we initially identified genes associated with tumor hypoxia and the immune microenvironment through GSEA and IMMPORT database analysis. We subsequently identified hypoxia- and immune-related genes associated with glioma prognosis through further cross-analysis and multidatabase integrated analysis. HSPA5 was ultimately identified as a potential target gene related to the formation of the hypoxic microenvironment and immune microenvironment in glioma. Furthermore, we conducted MTT, colony formation, EdU, migration and invasion assays and intracranial orthotopic tumor model analysis to further evaluate the impact of interfering with HSPA5 expression on the hypoxic and immune microenvironments of glioma.

RESULTS

We found that HSPA5 is highly expressed in glioma cells and tissues and is associated with a poor prognosis. Further investigation revealed that hypoxia promotes the malignant biological characteristics of glioma and reshaping the Immunosuppressive phenotype of tumor-associated macrophages (TAMs) through upregulation of the HIF-1α/HSPA5 axis. Silencing HSPA5 alleviated glioma hypoxia tolerance and induced the polarization of TAMs toward the M1 phenotype. The induced macrophages could exhibit a tumor-suppressive effect.

CONCLUSION

These observations suggest that HSPA5 upregulation promotes glioma progression by inducing hypoxia tolerance and reshaping the Immunosuppressive phenotype of TAMs. Therefore, targeting HSPA5 may be a novel therapeutic strategy for glioma.

LRP5 enhances glioma cell proliferation by modulating the MAPK/p53/cdc2 pathway

Background: Glioma is a malignant neoplasm with generally poor prognosis and the treatment options and effective drugs are very limited. LRP5, a member of the low-density lipoprotein receptor (LDLR) gene family, has been reported to regulate the progression of various cancers such as gastric and colorectal cancer. However, the function of LRP5 in glioma has not been elucidated. The objective of this study is to explore the influence of LRP5 in glioma cell proliferation and its potential molecular mechanisms. Methods: LRP5 expression in glioma was assessed through bioinformatics analysis, and validation was conducted using clinical glioma tissues. Glioma cell lines with reduced LRP5 expression were established through RNA interference. A series of experiments such as cell proliferation assay, flow cytometry analysis, and Western blotting were used to determine the role of LRP5 in glioma cell proliferation, cell cycle progression, and the underlying mechanisms. Results: LRP5 was found to be upregulated in glioma tissues and exhibited significant variations across various subtypes of glioblastoma (GBM). When differentiating between normal individuals and glioma patients, the area under the receiver operating characteristic curve (ROC) for LRP5 was determined to be 0.981. Downregulating the expression of LRP5 in glioma cells can weaken their proliferative ability and reduce the number of cell colonies. There were more cells arrested in the G2/M phase of the cell cycle. The protein levels of phospho-p53 (p-p53), p21Cip1, and phospho-cdc2 (p-cdc2) were elevated. Moreover, LRP5 down-regulation suppressed the phosphorylation of the mitogen-activated protein kinase (MAPK) family members, JNK and p38 MAPK. Consistent results with those mentioned above can be achieved by using an LRP5 antagonist named DKK-1. Conclusion: This research has identified that LRP5 may promote glioma proliferation by influencing the G2/M transition and the activation of the MAPK/p53/cdc2 pathways, suggesting its value as a potential molecular target for glioma diagnosis and treatment.

Integrating machine learning with mendelian randomization for unveiling causal gene networks in glioblastoma multiforme

BACKGROUND

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer with poor prognosis and limited treatment options. Despite advances in understanding its molecular mechanisms, effective therapeutic strategies remain elusive due to the tumor's genetic complexity and heterogeneity.

METHODS

This study employed a comprehensive analysis approach integrating 113 machine learning algorithms with Mendelian Randomization (MR) analysis to investigate the molecular underpinnings of GBM. Five publicly available gene expression datasets were analyzed to identify differentially expressed genes (DEGs) associated with GBM. Weighted Gene Co-expression Network Analysis (WGCNA) was used to identify GBM-related gene modules. Further, gene set enrichment and variation analyses were conducted to explore the biological pathways involved. The machine learning models were evaluated using Receiver Operating Characteristic (ROC) curves and confusion matrices to assess their predictive accuracy, with the best-performing model validated across external datasets. MR analysis was performed to establish causal relationships between genetically predicted gene expression levels and GBM outcomes.

RESULTS

The study identified 286 DEGs between GBM and adjacent normal tissues across five datasets. WGCNA highlighted the yellow module as the most relevant to GBM, containing key genes such as KLHL3, FOXO4, and MAP1A. Of the 113 machine learning models tested, Ridge regression achieved the highest area under the curve (AUC) of 0.92, demonstrating robust predictive accuracy. Validation using external datasets confirmed the model's reliability, with a classification accuracy of 89.5% in the training set and 85.3% in the validation sets. MR analysis provided strong evidence of a causal relationship between the expression levels of the identified genes and GBM risk.

CONCLUSIONS

This study demonstrates the power of combining machine learning and Mendelian Randomization to uncover novel genetic markers for GBM. The identified genes offer promising potential as biomarkers for GBM diagnosis and therapy, providing new avenues for personalized treatment strategies.

Tumoroid-On-a-Plate (ToP): Physiologically Relevant Cancer Model Generation and Therapeutic Screening

Employing three-dimensional (3D) in vitro models, including tumor organoids and spheroids, stands pivotal in enhancing cancer therapy. These models bridge the gap between two-dimensional (2D) cell cultures and complex in vivo environments and offer versatile tools for comprehensive studies into cancer progression, drug responses, and tailored therapies. This study introduces the Tumoroid-on-a-Plate (ToP) device, an innovative ope-surface microfluidic platform designed to create predictive 3D models of solid tumors. The ToP device combines tumor mass, stromal cells, and extracellular matrix (ECM) components, to closely replicate the microenvironment of glioblastoma (GBM) and pancreatic adenocarcinoma (PDAC). Using the advanced ToP model and testing various GBM ECM compositions such as collagen and Rreelin within the model, we can assess how specific elements affect GBM invasiveness. The ToP in vitro model also enables screening chemotherapeutics such as temozolomide and iron-chelators in a single and binary treatment setting on the complex ECM-embedded tumoroids to evaluate their toxicity on GBM and PDAC models viability and apoptosis. Furthermore, co-culturing PDAC tumoroids with human-derived fibroblasts reveals the pro-invasive influence of stromal elements on tumor growth and drug response. This research underscores the value of advanced 3D models like ToP in advancing the understanding of cancer complexity and therapy responses.

Quantitative analysis of immune cells within the tumor microenvironment of glioblastoma and their relevance for prognosis

Glioblastoma (GBM) is a high malignant tumor with no effective treatment. To comprehensively characterize the landscape of immune cells in GBM and evaluate their correlation with prognosis, we developed a multispectral fluorescent imaging pipeline that included tumor-infiltrating lymphocytic markers (CD3, CD4, CD8, FOXP3, NKP46), immune checkpoint markers (PD-1, PD-L1), and markers to characterize myeloid cells (CD68, CD66b, CD163, HLA-DR), to spatially quantify 18 immune cell subsets in 21 GBM cases. We found that macrophages are the most abundant in GBM microenvironment, followed by T cells and neutrophils, while NK and NKT cells are the least. Previously unreported CD8+ Treg, PD-L1+ neutrophils, and high proportion of PD-1+ NK and PD-1+ T cells were also detected. Single high densities of PD-1+CD8+ T cells, neutrophils, and PD-L1-expressing CD68+ cells were associated with longer survival. Moreover, closer proximity of T cells to PD-L1+ macrophages or PD-L1+ neutrophils were associated with poor prognosis. Correlative analysis revealed circulating PMN-MDSC and e-MDSC were positively correlated with intratumoral M2 macrophages, while circulating NK cells were inversely associated with infiltrating CD4+ Treg cells in GBM patients. Our findings highlighted the potential roles of infiltrating immune cells in prognosis prediction and developing novel immunotherapeutic strategies for GBM patients.

Recent advances in biomimetic strategies for the immunotherapy of glioblastoma

Immunotherapy is regarded as one of the most promising approaches for treating tumors, with a multitude of immunotherapeutic thoughts currently under consideration for the lethal glioblastoma (GBM). However, issues with immunotherapeutic agents, such as limited in vivo stability, poor blood-brain barrier (BBB) penetration, insufficient GBM targeting, and represented monotherapy, have hindered the success of immunotherapeutic interventions. Moreover, even with the aid of conventional drug delivery systems, outcomes remain suboptimal. Biomimetic strategies seek to overcome these formidable drug delivery challenges by emulating nature's intelligent structures and functions. Leveraging the variety of biological structures and functions, biomimetic drug delivery systems afford a versatile platform with enhanced biocompatibility for the co-delivery of diverse immunotherapeutic agents. Moreover, their inherent capacity to traverse the BBB and home in on GBM holds promise for augmenting the efficacy of GBM immunotherapy. Thus, this review begins by revisiting the various thoughts and agents on immunotherapy for GBM. Then, the barriers to successful GBM immunotherapy are analyzed, and the corresponding biomimetic strategies are explored from the perspective of function and structure. Finally, the clinical translation's current state and prospects of biomimetic strategy are addressed. This review aspires to provide fresh perspectives on the advancement of immunotherapy for GBM.

Using Multi-Omics Analysis to Explore Diagnostic Tool and Optimize Drug Therapy Selection for Patients with Glioma Based on Cross-Talk Gene Signature

Background

The heterogeneity of prognosis and treatment benefits among patients with gliomas is due to tumor microenvironment characteristics. However, biomarkers that reflect microenvironmental characteristics and predict the prognosis of gliomas are limited. Therefore, we aimed to develop a model that can effectively predict prognosis, differentiate microenvironment signatures, and optimize drug selection for patients with glioma.

Materials and Methods

The CIBERSORT algorithm, bulk sequencing analysis, and single-cell RNA (scRNA) analysis were employed to identify significant cross-talk genes between M2 macrophages and cancer cells in glioma tissues. A predictive model was constructed based on cross-talk gene expression, and its effect on prognosis, recurrence prediction, and microenvironment characteristics was validated in multiple cohorts. The effect of the predictive model on drug selection was evaluated using the OncoPredict algorithm and relevant cellular biology experiments.

Results

A high abundance of M2 macrophages in glioma tissues indicates poor prognosis, and cross-talk between macrophages and cancer cells plays a crucial role in shaping the tumor microenvironment. Eight genes involved in the cross-talk between macrophages and cancer cells were identified. Among them, periostin (POSTN), chitinase 3 like 1 (CHI3L1), serum amyloid A1 (SAA1), and matrix metallopeptidase 9 (MMP9) were selected to construct a predictive model. The developed model demonstrated significant efficacy in distinguishing patient prognosis, recurrent cases, and characteristics of high inflammation, hypoxia, and immunosuppression. Furthermore, this model can serve as a valuable tool for guiding the use of trametinib.

Conclusions

In summary, this study provides a comprehensive understanding of the interplay between M2 macrophages and cancer cells in glioma; utilizes a cross-talk gene signature to develop a predictive model that can predict the differentiation of patient prognosis, recurrence instances, and microenvironment characteristics; and aids in optimizing the application of trametinib in glioma patients.

Mass Spectrometry Advances in Analysis of Glioblastoma

Some cancers such as glioblastoma (GBM), show minimal response to medical interventions, often only capable of mitigating tumor growth or alleviating symptoms. High metabolic activity in the tumor microenvironment marked by immune responses and hypoxia, is a crucial factor driving tumor progression. The many developments in mass spectrometry (MS) over the last decades have provided a pivotal tool for studying proteins, along with their posttranslational modifications. It is known that the proteomic landscape of GBM comprises a wide range of proteins involved in cell proliferation, survival, migration, and immune evasion. Combination of MS imaging and microscopy has potential to reveal the spatial and molecular characteristics of pathological tissue sections. Moreover, integration of MS in the surgical process in form of techniques such as DESI-MS or rapid evaporative ionization MS has been shown as an effective tool for rapid measurement of metabolite profiles, providing detailed information within seconds. In immunotherapy-related research, MS plays an indispensable role in detection and targeting of cancer antigens which serve as a base for antigen-specific therapies. In this review, we aim to provide detailed information on molecular profile in GBM and to discuss recent MS advances and their clinical benefits for targeting this aggressive disease.

Fibrillar extracellular matrix produced by pericyte-like cells facilitates glioma cell dissemination

Gliomagenesis induces profound changes in the composition of the extracellular matrix (ECM) of the brain. In this study, we identified a cellular population responsible for the increased deposition of collagen I and fibronectin in glioblastoma. Elevated levels of the fibrillar proteins collagen I and fibronectin were associated with the expression of fibroblast activation protein (FAP), which is predominantly found in pericyte-like cells in glioblastoma. FAP+ pericyte-like cells were present in regions rich in collagen I and fibronectin in biopsy material and produced substantially more collagen I and fibronectin in vitro compared to other cell types found in the GBM microenvironment. Using mass spectrometry, we demonstrated that 3D matrices produced by FAP+ pericyte-like cells are rich in collagen I and fibronectin and contain several basement membrane proteins. This expression pattern differed markedly from glioma cells. Finally, we have shown that ECM produced by FAP+ pericyte-like cells enhances the migration of glioma cells including glioma stem-like cells, promotes their adhesion, and activates focal adhesion kinase (FAK) signaling. Taken together, our findings establish FAP+ pericyte-like cells as crucial producers of a complex ECM rich in collagen I and fibronectin, facilitating the dissemination of glioma cells through FAK activation.

Role of T Lymphocytes in Glioma Immune Microenvironment: Two Sides of a Coin

Glioma is known for its immunosuppressive microenvironment, which makes it challenging to target through immunotherapies. Immune cells like macrophages, microglia, myeloid-derived suppressor cells, and T lymphocytes are known to infiltrate the glioma tumor microenvironment and regulate immune response distinctively. Among the variety of immune cells, T lymphocytes have highly complex and multifaceted roles in the glioma immune landscape. T lymphocytes, which include CD4+ helper and CD8+ cytotoxic T cells, are known for their pivotal roles in anti-tumor responses. However, these cells may behave differently in the highly dynamic glioma microenvironment, for example, via an immune invasion mechanism enforced by tumor cells. Therefore, T lymphocytes play dual roles in glioma immunity, firstly by their anti-tumor responses, and secondly by exploiting gliomas to promote immune invasion. As an immunosuppression strategy, glioma induces T-cell exhaustion and suppression of effector T cells by regulatory T cells (Tregs) or by altering their signaling pathways. Further, the expression of immune checkpoint inhibitors on the glioma cell surface leads to T cell anergy and dysfunction. Overall, this dynamic interplay between T lymphocytes and glioma is crucial for designing more effective immunotherapies. The current review provides detailed knowledge on the roles of T lymphocytes in the glioma immune microenvironment and helps to explore novel therapeutic approaches to reinvigorate T lymphocytes.

Neuroinflammation in Glioblastoma: Progress and Perspectives

Glioblastoma is the most common and malignant primary brain tumor, with high morbidity and mortality. Despite an aggressive, multimodal treatment regimen, including surgical resection followed by chemotherapy and radiotherapy, the prognosis of glioblastoma patients remains poor. One formidable challenge to advancing glioblastoma therapy is the complexity of the tumor microenvironment. The tumor microenvironment of glioblastoma is a highly dynamic and heterogeneous system that consists of not only cancerous cells but also various resident or infiltrating inflammatory cells. These inflammatory cells not only provide a unique tumor environment for glioblastoma cells to develop and grow but also play important roles in regulating tumor aggressiveness and treatment resistance. Targeting the tumor microenvironment, especially neuroinflammation, has increasingly been recognized as a novel therapeutic approach in glioblastoma. In this review, we discuss the components of the tumor microenvironment in glioblastoma, focusing on neuroinflammation. We discuss the interactions between different tumor microenvironment components as well as their functions in regulating glioblastoma pathogenesis and progression. We will also discuss the anti-tumor microenvironment interventions that can be employed as potential therapeutic targets.

GBM Immunotherapy: Macrophage Impacts

BACKGROUND

Glioblastoma (GBM) is an extremely aggressive form of brain tumor with low survival rates. Current treatments such as chemotherapy, radiation, and surgery are problematic due to tumor growth, invasion, and tumor microenvironment. GBM cells are resistant to these standard treatments, and the heterogeneity of the tumor makes it difficult to find a universal approach. Progression of GBM and acquisition of resistance to therapy are due to the complex interplay between tumor cells and the TME. A significant portion of the TME consists of an inflammatory infiltrate, with microglia and macrophages being the predominant cells.

METHODS

Analysis of the literature data over a course of 5 years suggest that the tumor-associated macrophages (TAMs) are capable of releasing cytokines and growth factors that promote tumor proliferation, survival, and metastasis while inhibiting immune cell function at the same time.

RESULTS

Thus, immunosuppressive state, provided with this intensively studied kind of TME cells, is supposed to promote GBM development through TAMs modulation of tumor treatment-resistance and aggressiveness. Therefore, TAMs are an attractive therapeutic target in the treatment of glioblastoma.

CONCLUSION

This review provides a comprehensive overview of the latest research on the nature of TAMs and the development of therapeutic strategies targeting TAMs, focusing on the variety of macrophage properties, being modulated, as well as molecular targets.

Prognostic relevance of high expression of kynurenine pathway markers in glioblastoma

Glioblastoma (GBM) continues to exhibit a discouraging survival rate despite extensive research into new treatments. One factor contributing to its poor prognosis is the tumor's immunosuppressive microenvironment, in which the kynurenine pathway (KP) plays a significant role. This study aimed to explore how KP impacts the survival of newly diagnosed GBM patients. We examined tissue samples from 108 GBM patients to assess the expression levels of key KP markers-tryptophan 2,3-dioxygenase (TDO2), indoleamine 2,3-dioxygenase (IDO1/2), and the aryl hydrocarbon receptor (AhR). Using immunohistochemistry and QuPath software, three tumor cores were analyzed per patient to evaluate KP marker expression. Kaplan-Meier survival analysis and stepwise multivariate Cox regression were used to determine the effect of these markers on patient survival. Results showed that patients with high expression of TDO2, IDO1/2, and AhR had significantly shorter survival times. This finding held true even when controlling for other known prognostic variables, with a hazard ratio of 3.393 for IDO1, 2.775 for IDO2, 1.891 for TDO2, and 1.902 for AhR. We suggest that KP markers could serve as useful tools for patient stratification, potentially guiding future immunomodulating trials and personalized treatment approaches for GBM patients.

Unveiling novel cell clusters and biomarkers in glioblastoma and its peritumoral microenvironment at the single-cell perspective

BACKGROUND

Glioblastoma (GBM) is a highly heterogeneous, recurrent and aggressively invasive primary malignant brain tumor. The heterogeneity of GBM results in poor targeted therapy. Therefore, the aim of this study is to depict the cellular landscape of GBM and its peritumor from a single-cell perspective. Discovering new cell subtypes and biomarkers, and providing a theoretical basis for precision therapy.

METHODS

We collected 8 tissue samples from 4 GBM patients to perform 10 × single-cell transcriptome sequencing. Quality control and filtering of data by Seurat package for clustering. Inferring copy number variations to identify malignant cells via the infercnv package. Functional enrichment analysis was performed by GSVA and clusterProfiler packages. STRING database and Cytoscape software were used to construct protein interaction networks. Inferring transcription factors by pySCENIC. Building cell differentiation trajectories via the monocle package. To infer intercellular communication networks by CellPhoneDB software.

RESULTS

We observed that the tumor microenvironment (TME) varies among different locations and different GBM patients. We identified a proliferative cluster of oligodendrocytes with high expression of mitochondrial genes. We also identified two clusters of myeloid cells, one primarily located in the peritumor exhibiting an M1 phenotype with elevated TNFAIP8L3 expression, and another in the tumor and peritumor showing a proliferative tendency towards an M2 phenotype with increased DTL expression. We identified XIST, KCNH7, SYT1 and DIAPH3 as potential factors associated with the proliferation of malignant cells in GBM.

CONCLUSIONS

These biomarkers and cell clusters we discovered may serve as targets for treatment. Targeted drugs developed against these biomarkers and cell clusters may enhance treatment efficacy, optimize immune therapy strategies, and improve the response rates of GBM patients to immunotherapy. Our findings provide a theoretical basis for the development of individualized treatment and precision medicine for GBM, which may be used to improve the survival of GBM patients.

IGH Complementarity Determining Region-3-Cytomegalovirus Protein Chemical Complementarity Linked to Better Overall Survival Probabilities for Glioblastoma

Cytomegalovirus (CMV) has long been thought to have an association with glioblastoma multiforme (GBM), although the exact role of CMV and any subsequent implications for treatment have yet to be fully understood. This study addressed whether IGH complementarity determining region-3 (CDR3)-CMV protein chemical complementarity, with IGH CDR3s representing both tumor resident and blood-sourced IGH recombinations, was associated with overall survival (OS) distinctions. IGH recombination sequencing reads were obtained from (a) the Clinical Proteomic Tumor Analysis Consortium, tumor RNAseq files; and (b) the cancer genome atlas, blood exome-derived files. The Adaptive Match web tool was used to calculate chemical complementarity scores (CSs) based on hydrophobic interactions, and those scores were used to group GBM cases and assess survival probabilities. We found a higher OS probability for cases whose hydrophobic IGH CDR3-CMV protein chemical complementarity scores (Hydro CSs) were in the upper 50th percentile for several CMV proteins, including UL99 and UL123, as well as for CSs based on known B cell epitopes representing these proteins. We also identified multiple immune signature genes, including CD79A and TNFRSF17, for which higher RNA expression was associated with higher Hydro CSs. Results were consistent with the idea that stronger immunoglobulin responses to CMV are associated with better OS probabilities for GBM.

Synergistic Effects of Neratinib in Combination With Palbociclib or Miransertib in Brain Cancer Cells

Background

Aberrant expression and activation of epidermal growth factor receptor (EGFR) resulted in approval of several forms of EGFR inhibitors in the treatment of patients with a wide range of epithelial cancers. However, no EGFR inhibitor has yet been approved for the treatment of patients with brain cancer, indicating that targeting EGFR alone may not be sufficient in some patients.

Methods

In this study, we investigated the role of all members of the EGFR family, other growth factor receptors, cell-cycle proteins, and downstream cell signaling pathways (e.g., mitogen-activated protein kinase (MAPK), serine/threonine protein kinase (AKT), signal transducer and activator of transcription (STAT3), Src, Abelson murine leukemia viral oncogene homolog (Abl)) on the growth of a panel of human brain cancer cell lines (HBCCLs). We examined the growth response of HBCCLs to treatment with 17 targeted agents compared to two cytotoxic drugs.

Results

Of the targeted agents, the irreversible pan-human epidermal growth factor receptor (HER) inhibitors neratinib and afatinib were more effective than erlotinib and lapatinib at inhibiting the growth of all HBCCLs, and the cyclin-dependent kinase (CDK)1/2/5/9 inhibitor dinaciclib was the most potent targeted agent. We found that treatment with Src/Abl/c-kit inhibitor dasatinib, signal transducer and activator of transcription (STAT3) inhibitor stattic, Abl/platelet-derived growth factor receptor (PDGFR)α/vascular endothelial growth factor (VEGFR)2/fibroblast growth factor receptor (FGFR)1 inhibitor ponatinib, and the tropomyosin receptor kinase (TRK)/ROS proto-oncogene 1 receptor tyrosine kinase (ROS)/anaplastic lymphoma kinase (ALK) inhibitor entrectinib, also inhibited the growth of all HBCCLs. Interestingly, these agents were more effective in inhibiting growth of HBCCLs when proliferating at a slower rate. In addition to inhibiting the proliferation of HBCCLs, treatment with neratinib, dinaciclib, dasatinib, stattic and trametinib inhibited the migration of brain tumor cell line A172.

Conclusions

Notably, we found that treatment with neratinib in combination with palbociclib (CDK4/6 inhibitor), or miransertib (AKT1/2/3 inhibitor) resulted in synergistic growth inhibition of all HBCCLs. Our results support that repurposing drugs like neratinib in combination with the palbociclib or miransertib may be of therapeutic potential in brain cancer and warrants further investigations.

Microglia and glioblastoma heterocellular interplay sustains tumour growth and proliferation as an off-target effect of radiotherapy

Glioblastoma (GBM), a WHO grade IV glioma, is a malignant primary brain tumour for which combination of surgery, chemotherapy and radiotherapy is the first-line approach despite adverse effects. Tumour microenvironment (TME) is characterized by an interplay of cells and soluble factors holding a critical role in neoplastic development. Significant pathophysiological changes have been found in GBM TME, such as glia activation and oxidative stress. Microglia play a crucial role in favouring GBM growth, representing target cells of immune escape mechanisms. Our study aims at analysing radiation-induced effects in modulating intercellular communication and identifying the basis of protective mechanisms in radiation-naïve GBM cells. Tumour cells were treated with conditioned media (CM) derived from 0, 2 or 15 Gy irradiated GBM cells or 0, 2 or 15 Gy irradiated human microglia. We demonstrated that irradiated microglia promote an increase of GBM cell lines proliferation through paracrine signalling. On the contrary, irradiated GBM-derived CM affect viability, triggering cell death mechanisms. In addition, we investigated whether these processes involve mitochondrial mass, fitness and oxidative phosphorylation and how GBM cells respond at these induced alterations. Our study suggests that off-target radiotherapy modulates microglia to support GBM proliferation and induce metabolic modifications.

IFI35 regulates non-canonical NF-κB signaling to maintain glioblastoma stem cells and recruit tumor-associated macrophages

Glioblastoma (GBM) is the most aggressive malignant primary brain tumor characterized by a highly heterogeneous and immunosuppressive tumor microenvironment (TME). The symbiotic interactions between glioblastoma stem cells (GSCs) and tumor-associated macrophages (TAM) in the TME are critical for tumor progression. Here, we identified that IFI35, a transcriptional regulatory factor, plays both cell-intrinsic and cell-extrinsic roles in maintaining GSCs and the immunosuppressive TME. IFI35 induced non-canonical NF-kB signaling through proteasomal processing of p105 to the DNA-binding transcription factor p50, which heterodimerizes with RELB (RELB/p50), and activated cell chemotaxis in a cell-autonomous manner. Further, IFI35 induced recruitment and maintenance of M2-like TAMs in TME in a paracrine manner. Targeting IFI35 effectively suppressed in vivo tumor growth and prolonged survival of orthotopic xenograft-bearing mice. Collectively, these findings reveal the tumor-promoting functions of IFI35 and suggest that targeting IFI35 or its downstream effectors may provide effective approaches to improve GBM treatment.

AS1411 binds to nucleolin via its parallel structure and disrupts the exos-miRNA-27a-mediated reciprocal activation loop between glioma and astrocytes

The interaction between glioma cells and astrocytes promotes the proliferation of gliomas. Micro-RNAs (miRNAs) carried by astrocyte exosomes (exos) may be involved in this process, but the mechanism remains unclear. The oligonucleotide AS1411, which consists of 26 bases and has a G-quadruplex structure, is an aptamer that targets nucleolin. In this study, we demonstrate exosome-miRNA-27a-mediated cross-activation between astrocytes and glioblastoma and show that AS1411 reduces astrocytes' pro-glioma activity. The enhanced affinity of AS1411 toward nucleolin is attributed to its G-quadruplex structure. After binding to nucleolin, AS1411 inhibits the entry of the NF-κB pathway transcription factor P65 into the nucleus, then downregulates the expression of miRNA-27a in astrocytes surrounding gliomas. Then, AS1411 downregulates astrocyte exosome-miRNA-27a and upregulates the expression of INPP4B, the target gene of miRNA-27a in gliomas, thereby inhibiting the PI3K/AKT pathway and inhibiting glioma proliferation. These results were verified in mouse orthotopic glioma xenografts and human glioma samples. In conclusion, the parallel structure of AS1411 allows it to bind to nucleolin and disrupt the exosome-miRNA-27a-mediated reciprocal activation loop between glioma cells and astrocytes. Our results may help in the development of a novel approach to therapeutic modulation of the glioma microenvironment.

Novel Acetamide-Based HO-1 Inhibitor Counteracts Glioblastoma Progression by Interfering with the Hypoxic-Angiogenic Pathway

Glioblastoma multiforme (GBM) represents the deadliest tumor among brain cancers. It is a solid tumor characterized by uncontrolled cell proliferation generating the hypoxic niches in the cancer core. By inducing the transcription of hypoxic inducible factor (HIF), hypoxia triggers many signaling cascades responsible for cancer progression and aggressiveness, including enhanced expression of vascular endothelial growth factor (VEGF) or antioxidant enzymes, such as heme oxygenase-1 (HO-1). The present work aimed to investigate the link between HO-1 expression and the hypoxic microenvironment of GBM by culturing two human glioblastoma cell lines (U87MG and A172) in the presence of a hypoxic mimetic agent, deferoxamine (DFX). By targeting hypoxia-induced HO-1, we have tested the effect of a novel acetamide-based HO-1 inhibitor (VP18/58) on GBM progression. Results have demonstrated that hypoxic conditions induced upregulation and nuclear expression of HO-1 in a cell-dependent manner related to malignant phenotype. Moreover, our data demonstrated that the HO-1 inhibitor counteracted GBM progression by modulating the HIFα/HO-1/VEGF signaling cascade in cancer cells bearing more malignant phenotypes.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

Bulk and single cells transcriptomes with experimental validation identify USP18 as a novel glioma prognosis and proliferation indicator

The mechanism by which ubiquitin-specific protease 18 (USP18) (enzyme commission: 3.4.19.12) inhibition in cancer promotes cell pyroptosis via the induction of interferon (IFN)-stimulated genes has been recently demonstrated. It is also known that USP18 influences the epithelial-mesenchymal transition of glioma cells. In the present study, the upregulation of USP18 in glioma was revealed through bulk transcriptome analysis, which was associated with poor prognosis in patients with glioma. Furthermore, USP18 levels affected the response to immunotherapy in patients with glioma. Single-cell transcriptome and enrichment analyses demonstrated that USP18 was associated with type 1 IFN responses in glioma T cells. To demonstrate the effect of USP18 expression levels on glioma cells, USP18 expression was knocked down in U251 and U87MG ATCC cell lines. A subsequent Cell Counting Kit-8 assay revealed that glioma cell viability was significantly decreased 4 days after USP18 knockdown. In addition, the knockdown of USP18 expression significantly inhibited the clonogenicity of U251 and U87MG ATCC cells. In conclusion, the present study demonstrated that knockdown of USP18 expression inhibited the proliferation of glioma cells, which may be mediated by the effect of USP18 on the IFN-I response.

Hypoxia effects on glioblastoma progression through YAP/TAZ pathway regulation

The resistance of glioblastomas (GBM) to standard therapies poses a clinical challenge with limited survival despite interventions. The tumor microenvironment (TME) orchestrates GBM progression, comprising stromal and immune cells and is characterized by extensive hypoxic regions. Hypoxia activates the hypoxia-inducible factor 1 alpha (HIF-1α) pathway, interacting with the Hippo pathway (YAP/TAZ) in crucial cellular processes. We discuss here the related signaling crosstalk between YAP/TAZ and regions of hypoxia in the TME with particular attention on the MST1/2 and LATS1/2-regulated YAP/TAZ activation, impacting cell proliferation, invasion, and stemness. Moreover, the hypoxia-YAP/TAZ axis influence on angiogenesis, stem cells, and metabolic regulators is defined. By reviewing extracellular matrix alterations activation of YAP/TAZ, modulation of signaling pathways we also discuss the significance of spatial constraints and epigenetic modifications contribution to GBM progression, with potential therapeutic targets in YAP/TAZ-mediated gene regulation. Comprehensive understanding of the hypoxia-Hippo pathway-TME interplay offers insights for novel therapeutic strategies, aiming to provide new directions for treatment.

Gene expression analysis suggests immunosuppressive roles of endolysosomes in glioblastoma

Targeting endolysosomes is a strategy extensively pursued for treating cancers, including glioblastomas (GBMs), on the basis that the intact function of these subcellular organelles is key to tumor cell autophagy and survival. Through gene expression analyses and cell type abundance estimation in GBMs, we showed that genes associated with the endolysosomal machinery are more prominently featured in non-tumor cells in GBMs than in tumor cells, and that tumor-associated macrophages represent the primary immune cell type that contributes to this trend. Further analyses found an enrichment of endolysosomal pathway genes in immunosuppressive (pro-tumorigenic) macrophages, such as M2-like macrophages or those associated with worse prognosis in glioma patients, but not in those linked to inflammation (anti-tumorigenic). Specifically, genes critical to the hydrolysis function of endolysosomes, including progranulin and cathepsins, were among the most positively correlated with immunosuppressive macrophages, and elevated expression of these genes is associated with worse patient survival in GBMs. Together, these results implicate the hydrolysis function of endolysosomes in shaping the immunosuppressive microenvironment of GBM. We propose that targeting endolysosomes, in addition to its detrimental effects on tumor cells, can be leveraged for modulating immunosuppression to render GBMs more amenable to immunotherapies.

Glioblastoma: An Update in Pathology, Molecular Mechanisms and Biomarkers

Glioblastoma multiforme (GBM) is the most common and malignant type of primary brain tumor in adults. Despite important advances in understanding the molecular pathogenesis and biology of this tumor in the past decade, the prognosis for GBM patients remains poor. GBM is characterized by aggressive biological behavior and high degrees of inter-tumor and intra-tumor heterogeneity. Increased understanding of the molecular and cellular heterogeneity of GBM may not only help more accurately define specific subgroups for precise diagnosis but also lay the groundwork for the successful implementation of targeted therapy. Herein, we systematically review the key achievements in the understanding of GBM molecular pathogenesis, mechanisms, and biomarkers in the past decade. We discuss the advances in the molecular pathology of GBM, including genetics, epigenetics, transcriptomics, and signaling pathways. We also review the molecular biomarkers that have potential clinical roles. Finally, new strategies, current challenges, and future directions for discovering new biomarkers and therapeutic targets for GBM will be discussed.

Biodistribution and pharmacokinetics of [89Zr]-anti-VEGF mAbs using PET in glioblastoma rat models

INTRODUCTION

Glioblastomas present intensive angiogenesis, thus anti-Vascular Endothelial Growth Factor (VEGF) antibodies (mAbs) have been proposed as promising therapies. However, the results of clinical trials reported moderate toxicity and limited effectiveness. This study evaluates the in vivo pharmacokinetics and biodistribution of these mAbs in a growing model of glioblastoma in rats using Positron Emission Tomography (PET).

MATERIAL

&Methods: mAbs were radiolabeled with zirconium-89. Four days after the model induction, animals were injected with 2.33 ± 1.3 MBq of [89Zr]-DFO-bevacizumab (n = 8) or 2.35 ± 0.26 MBq of [89Zr]-DFO-aflibercept (n = 6). PETs were performed at 0H, 48H, 168H, 240H, and 336H post-injection. Tumor induction was confirmed using [18F]-Fluorodeoxyglucose-PET and immunohistochemistry. Radiotracer uptake was estimated in all pre-defined Volumes-of-Interest.

RESULTS

Anti-VEGF mAbs showed 100 % Radiochemical-Purity. [89Zr]-DFO-bevacizumab showed a significantly higher bioavailability in whole-blood. A significant increase in the tumor uptake was detectable at 168H PET with [89Zr]-DFO-bevacizumab meanwhile with [89Zr]-DFO-aflibercept it was only detectable at 336H. [89Zr]-DFO-bevacizumab tumor uptake was significantly higher than that of [89Zr]-DFO-aflibercept in all the scans. Tumor induction was confirmed in all animal models.

CONCLUSION

MAbs detect VEGF-expression in glioblastoma models. Tumors were earlier targeted by Bevacizumab. The lower blood availability of aflibercept resulted in a lower tumor uptake than bevacizumab in all the scans.

Epigenetic remodeling to improve the efficacy of immunotherapy in human glioblastoma: pre-clinical evidence for development of new immunotherapy approaches

BACKGROUND

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor, that is refractory to standard treatment and to immunotherapy with immune-checkpoint inhibitors (ICI). Noteworthy, melanoma brain metastases (MM-BM), that share the same niche as GBM, frequently respond to current ICI therapies. Epigenetic modifications regulate GBM cellular proliferation, invasion, and prognosis and may negatively regulate the cross-talk between malignant cells and immune cells in the tumor milieu, likely contributing to limit the efficacy of ICI therapy of GBM. Thus, manipulating the tumor epigenome can be considered a therapeutic opportunity in GBM.

METHODS

Microarray transcriptional and methylation profiles, followed by gene set enrichment and IPA analyses, were performed to study the differences in the constitutive expression profiles of GBM vs MM-BM cells, compared to the extracranial MM cells and to investigate the modulatory effects of the DNA hypomethylating agent (DHA) guadecitabine among the different tumor cells. The prognostic relevance of DHA-modulated genes was tested by Cox analysis in a TCGA GBM patients' cohort.

RESULTS

The most striking differences between GBM and MM-BM cells were found to be the enrichment of biological processes associated with tumor growth, invasion, and extravasation with the inhibition of MHC class II antigen processing/presentation in GBM cells. Treatment with guadecitabine reduced these biological differences, shaping GBM cells towards a more immunogenic phenotype. Indeed, in GBM cells, promoter hypomethylation by guadecitabine led to the up-regulation of genes mainly associated with activation, proliferation, and migration of T and B cells and with MHC class II antigen processing/presentation. Among DHA-modulated genes in GBM, 7.6% showed a significant prognostic relevance. Moreover, a large set of immune-related upstream-regulators (URs) were commonly modulated by DHA in GBM, MM-BM, and MM cells: DHA-activated URs enriched for biological processes mainly involved in the regulation of cytokines and chemokines production, inflammatory response, and in Type I/II/III IFN-mediated signaling; conversely, DHA-inhibited URs were involved in metabolic and proliferative pathways.

CONCLUSIONS

Epigenetic remodeling by guadecitabine represents a promising strategy to increase the efficacy of cancer immunotherapy of GBM, supporting the rationale to develop new epigenetic-based immunotherapeutic approaches for the treatment of this still highly deadly disease.

Crosstalk between glioblastoma and tumor microenvironment drives proneural-mesenchymal transition through ligand-receptor interactions

Glioblastoma (GBM) is the most common intrinsic and aggressive primary brain tumor in adults, with a median survival of approximately 15 months. GBM heterogeneity is considered responsible for the treatment resistance and unfavorable prognosis. Proneural-mesenchymal transition (PMT) represents GBM malignant progression and recurrence, which might be a breakthrough to understand GBM heterogeneity and overcome treatment resistance. PMT is a complicated process influenced by crosstalk between GBM and tumor microenvironment, depending on intricate ligand-receptor interactions. In this review, we summarize the autocrine and paracrine pathways in the GBM microenvironment and related ligand-receptor interactions inducing PMT. We also discuss the current therapies targeting the PMT-related autocrine and paracrine pathways. Together, this review offers a comprehensive understanding of the failure of GBM-targeted therapy and ideas for future tendencies of GBM treatment.

Integrated multiomic analysis reveals disulfidptosis subtypes in glioblastoma: implications for immunotherapy, targeted therapy, and chemotherapy

Introduction

Glioblastoma (GBM) presents significant challenges due to its malignancy and limited treatment options. Precision treatment requires subtyping patients based on prognosis. Disulfidptosis, a novel cell death mechanism, is linked to aberrant glucose metabolism and disulfide stress, particularly in tumors expressing high levels of SLC7A11. The exploration of disulfidptosis may provide a new perspective for precise diagnosis and treatment of glioblastoma.

Methods

Transcriptome sequencing was conducted on samples from GBM patients treated at Tiantan Hospital (January 2022 - December 2023). Data from CGGA and TCGA databases were collected. Consensus clustering based on disulfidptosis features categorized GBM patients into two subtypes (DRGclusters). Tumor immune microenvironment, response to immunotherapy, and drug sensitivity were analyzed. An 8-gene disulfidptosis-based subtype predictor was developed using LASSO machine learning algorithm and validated on CGGA dataset.

Results

Patients in DRGcluster A exhibited improved overall survival (OS) compared to DRGcluster B. DRGcluster subtypes showed differences in tumor immune microenvironment and response to immunotherapy. The predictor effectively stratified patients into high and low-risk groups. Significant differences in IC50 values for chemotherapy and targeted therapy were observed between risk groups.

Discussion

Disulfidptosis-based classification offers promise as a prognostic predictor for GBM. It provides insights into tumor immune microenvironment and response to therapy. The predictor aids in patient stratification and personalized treatment selection, potentially improving outcomes for GBM patients.

SYSTEMIC INFLAMMATORY INDICES IN PATIENTS WITH MALIGNANT GLIOMAS AND EFFECTS OF PLATELET SECRETOME IN VITRO

BACKGROUND

To date, no significant clinical progress has been achieved in the treatment of brain malignant gliomas (MG), and the active search for non-invasive circulating biomarkers continues. The prognostic significance of the ratio of the main peripheral blood cell populations of patients with MG is evaluated. Considerable attention is paid to the secretome of platelets (Pt) of peripheral blood.

AIM

To evaluate the indicators of the peripheral blood cell population ratios in patients with brain MG and to study the influence of the secretome of Pt (SPt) of the peripheral blood of patients with brain MG in cell cultures in vitro.

MATERIALS AND METHODS

We studied samples of peripheral blood from patients with glioma CNS WHO grade G2 (n = 5), G3 (n = 12), and G4 (n = 20). The peripheral blood cell counts were analyzed in the preoperative period on an automatic hematology analyzer. The in vitro study of SPt was performed on the U251 human glioblastoma cell line cultured with SPt from MG patients or SPt pre-incubated with anti-TGF-β1 antibody. Cell cultures were observed for 72 h, and mitotic index (MI) was calculated.

RESULTS

In MG patients, the count of peripheral blood leukocytes and neutrophils increased (p < 0.05). The neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) increased by 2-3 times compared to control. Nevertheless, correlation analysis did not reveal significant relationships between quantitative indicators of peripheral blood cells and the tumor malignancy degree in MG patients. The MI in U251 cells increased under the influence of SPt from patients with MG (p < 0.021), correlated with the tumor degree of malignancy (r = 0.246, p = 0.014). Pre-incubation of SPt with anti-TGF-β1 antibody tends to neutralize this promitotic effect.

CONCLUSION

In MG patients, the integral indicators of NLR and SII increased but no significant relationship with the degree of tumor malignancy was found. In U251 cells, promitotic effects of SPt of MG patients partially decreased by anti-TGF-β1 antibody.

Tumor-associated microenvironment, PD-L1 expression and their relationship with immunotherapy in glioblastoma, IDH-wild type: A comprehensive review with emphasis on the implications for neuropathologists

Although novel knowledge has been acquired on the molecular landscape of glioblastoma (GBM), a relatively few steps forward have been made regarding its therapy. With the increasing use of novel immunotherapeutic drugs capable of stimulating the antitumor inflammatory response, in the last decades numerous studies aimed to characterize the tumor-associated microenvironment (TME) and its relationship with the immunogenicity of GBM. In this regard, although the tumor-associated microglia and macrophages (TAMs) and PD-L1/PD-1 axis have been emerged as one of the most relevant components of the GBM TME and one of the potential molecular pathways targetable with immunotherapy, respectively. It has been supposed that TAMs may acquire different phenotypes, switching from M1 to M2 phenotypes, with tumor-suppressive and tumor-stimulating role depending on the different surrounding conditions. PD-L1 is a type 1 transmembrane protein ligand expressed by T-cells, B-cells and antigen-presenting cells, with a main inhibitory checkpoint role on tumor immune regulation. While PD-L1 immunohistochemical expression has been extensively investigated in many cancers, its usefulness in the evaluation of GBM response rates to immunotherapy and its standardized evaluation by immunohistochemistry are still debated. The present review paper focuses on the current "state of the art" about the relationship between TME, PD-L1/PD-1 pathway and immunotherapy in GBM, also providing neuropathologists with an updated guide about the clinical trials conducted with PD-L1 and PD-1 inhibitors.

Immunoediting Dynamics in Glioblastoma: Implications for Immunotherapy Approaches

Glioblastoma is an aggressive primary brain tumor that poses many therapeutic difficulties because of the high rate of proliferation, genetic variability, and its immunosuppressive microenvironment. The theory of cancer immunoediting, which includes the phases of elimination, equilibrium, and escape, offers a paradigm for comprehending interactions between the immune system and glioblastoma. Immunoediting indicates the process by which immune cells initially suppress tumor development, but thereafter select for immune-resistant versions leading to tumor escape and progression. The tumor microenvironment (TME) in glioblastoma is particularly immunosuppressive, with regulatory T cells and myeloid-derived suppressor cells being involved in immune escape. To achieve an efficient immunotherapy for glioblastoma, it is crucial to understand these mechanisms within the TME. Existing immunotherapeutic modalities such as chimeric antigen receptor T cells and immune checkpoint inhibitors have been met with some level of resistance because of the heterogeneous nature of the immune response to glioblastoma. Solving these issues is critical to develop novel strategies capable of modulating the TME and re-establishing normal immune monitoring. Further studies should be conducted to identify the molecular and cellular events that underlie the immunosuppressive tumor microenvironment in glioblastoma. Comprehending and modifying the stages of immunoediting in glioblastoma could facilitate the development of more potent and long-lasting therapies.

Identification of Necroptosis-related Molecular Subtypes and Construction of Necroptosis-related Gene Signature for Glioblastoma Multiforme

BACKGROUND

Necroptosis is a highly regulated and genetically controlled process, and therefore, attention has been paid to the exact effects of this disorder on a variety of diseases, including cancer. An in-depth understanding of the key regulatory factors and molecular events that trigger necroptosis can not only identify patients at risk of cancer development but can also help to develop new treatment strategies.

AIMS

This study aimed to increase understanding of the complex role of necroptosis in glioblastoma multiforme (GBM) and provide a new perspective and reference for accurate prediction of clinical outcomes and gene-targeted therapy in patients with GBM. The objective of this study was to analyze the gene expression profile of necroptosis regulatory factors in glioblastoma multiforme (GBM) and establish a necroptosis regulatory factor-based GBM classification and prognostic gene signature to recognize the multifaceted impact of necroptosis on GBM.

METHODS

The necroptosis score of the glioblastoma multiforme (GBM) sample in TCGA was calculated by ssGSEA, and the correlation between each gene and the necroptosis score was calculated. Based on necroptosis score-related genes, unsupervised consensus clustering was employed to classify patients. The prognosis, tumor microenvironment (TME), genomic changes, biological signal pathways and gene expression differences among clusters were analyzed. The gene signature of GBM was constructed by Cox and LASSO regression analysis of differentially expressed genes (DEGs).

RESULT

Based on 34 necroptosis score-related genes, GBM was divided into two clusters with different overall survival (OS) and TME. A necroptosis-related gene signature (NRGS) containing 8 genes was developed, which could stratify the risk of GBM in both the training set and verification set and had good prognostic value. NRGS and age were both independent prognostic indicators of GBM, and a nomogram developed by the integration of both of them showed a better predictive effect than traditional clinical features.

CONCLUSION

In this study, patients from public data sets were divided into two clusters and the unique TME and molecular characteristics of each cluster were described. Furthermore, an NRGS was constructed to effectively and independently predict the survival outcome of GBM, which provides some insights for the implementation of personalized precision medicine in clinical practice.

Novel Therapies in Glioblastoma Treatment: Review of Glioblastoma; Current Treatment Options; and Novel Oncolytic Viral Therapies

One of the most prevalent primary malignant brain tumors is glioblastoma (GB). About 6 incidents per 100,000 people are reported annually. Most frequently, these tumors are linked to a poor prognosis and poor quality of life. There has been little advancement in the treatment of GB. In recent years, some innovative medicines have been tested for the treatment of newly diagnosed cases of GB and recurrent cases of GB. Surgery, radiotherapy, and alkylating chemotherapy are all common treatments for GB. A few of the potential alternatives include immunotherapy, tumor-treating fields (TTFs), and medications that target specific cellular receptors. To provide new multimodal therapies that focus on the molecular pathways implicated in tumor initiation and progression in GB, novel medications, delivery technologies, and immunotherapy approaches are being researched. Of these, oncolytic viruses (OVs) are among the most recent. Coupling OVs with certain modern treatment approaches may have significant benefits for GB patients. Here, we discuss several OVs and how they work in conjunction with other therapies, as well as virotherapy for GB. The study was based on the PRISMA guidelines. Systematic retrieval of information was performed on PubMed. A total of 307 articles were found in a search on oncolytic viral therapies for glioblastoma. Out of these 83 articles were meta-analyses, randomized controlled trials, reviews, and systematic reviews. A total of 42 articles were from the years 2018 to 2023. Appropriate studies were isolated, and important information from each of them was understood and entered into a database from which the information was used in this article. One of the most prevalent malignant brain tumors is still GB. Significant promise and opportunity exist for oncolytic viruses in the treatment of GB and in boosting immune response. Making the most of OVs in the treatment of GB requires careful consideration and evaluation of a number of its application factors.

Review: therapeutic approaches for circadian modulation of the glioma microenvironment

High-grade gliomas are malignant brain tumors that are characteristically hard to treat because of their nature; they grow quickly and invasively through the brain tissue and develop chemoradiation resistance in adults. There is also a distinct lack of targeted treatment options in the pediatric population for this tumor type to date. Several approaches to overcome therapeutic resistance have been explored, including targeted therapy to growth pathways (ie. EGFR and VEGF inhibitors), epigenetic modulators, and immunotherapies such as Chimeric Antigen Receptor T-cell and vaccine therapies. One new promising approach relies on the timing of chemotherapy administration based on intrinsic circadian rhythms. Recent work in glioblastoma has demonstrated temporal variations in chemosensitivity and, thus, improved survival based on treatment time of day. This may be due to intrinsic rhythms of the glioma cells, permeability of the blood brain barrier to chemotherapy agents, the tumor immune microenvironment, or another unknown mechanism. We review the literature to discuss chronotherapeutic approaches to high-grade glioma treatment, circadian regulation of the immune system and tumor microenvironment in gliomas. We further discuss how these two areas may be combined to temporally regulate and/or improve the effectiveness of immunotherapies.

ROS regulation in gliomas: implications for treatment strategies

Gliomas are one of the most common primary malignant tumours of the central nervous system (CNS), of which glioblastomas (GBMs) are the most common and destructive type. The glioma tumour microenvironment (TME) has unique characteristics, such as hypoxia, the blood-brain barrier (BBB), reactive oxygen species (ROS) and tumour neovascularization. Therefore, the traditional treatment effect is limited. As cellular oxidative metabolites, ROS not only promote the occurrence and development of gliomas but also affect immune cells in the immune microenvironment. In contrast, either too high or too low ROS levels are detrimental to the survival of glioma cells, which indicates the threshold of ROS. Therefore, an in-depth understanding of the mechanisms of ROS production and scavenging, the threshold of ROS, and the role of ROS in the glioma TME can provide new methods and strategies for glioma treatment. Current methods to increase ROS include photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT), etc., and methods to eliminate ROS include the ingestion of antioxidants. Increasing/scavenging ROS is potentially applicable treatment, and further studies will help to provide more effective strategies for glioma treatment.