The Microenvironmental Landscape of Brain Tumors

Hormonal and neuronal interactions shaping the brain metastatic microenvironment

Metastatic progression drives the majority of cancer-related fatalities, and involvement of the central nervous system (CNS) poses especially formidable challenges to patients and clinicians. Brain metastases (BrM), commonly originate from lung, breast and melanoma cancers, and carry disproportionately poor outcomes. Although therapeutic advances have extended survival for many extracranial tumors, BrM incidence continues to climb-underscoring critical knowledge gaps in understanding the unique biology of tumor colonization in the CNS. While definitive evidence remains limited, a growing focus on cancer neuroscience-especially regarding hormone dependent cancer cells in the brain-has begun to reveal that factors normally regulated by sex steroids and neurosteroids may similarly influence the specialized metastatic microenvironment in the CNS. Steroid hormones can permeate the blood-brain barrier (BBB) or be synthesized de novo by astrocytes and other CNS-resident cells, potentially influencing processes such as inflammation, synaptic plasticity, and immune surveillance. However, how these hormonal pathways are co-opted by disseminated cancer cells remains unclear. Here, we review the complex hormonal landscape of the adult brain and examine how neuroendocrine-immune interactions, often regulated by sex hormones, may support metastatic growth. We discuss the interplay between systemic hormones, local steroidogenesis, and tumor adaptation to identify novel therapeutic opportunities.

Challenges and material innovations in drug delivery to central nervous system tumors

Central nervous system (CNS) tumors, encompassing a diverse array of neoplasms in the brain and spinal cord, pose significant therapeutic challenges due to their intricate anatomy and the protective presence of the blood-brain barrier (BBB). The primary treatment obstacle is the effective delivery of therapeutics to the tumor site, which is hindered by multiple physiological, biological, and technical barriers, including the BBB. This comprehensive review highlights recent advancements in material science and nanotechnology aimed at surmounting these delivery challenges, with a focus on the development and application of nanomaterials. Nanomaterials emerge as potent tools in designing innovative drug delivery systems that demonstrate the potential to overcome the limitations posed by CNS tumors. The review delves into various strategies, including the use of lipid nanoparticles, polymeric nanoparticles, and inorganic nanoparticles, all of which are engineered to enhance drug stability, BBB penetration, and targeted tumor delivery. Additionally, this review highlights the burgeoning role of theranostic nanoparticles, integrating therapeutic and diagnostic functionalities to optimize treatment efficacy. The exploration extends to biocompatible materials like biodegradable polymers, liposomes, and advanced material-integrated delivery systems such as implantable drug-eluting devices and microfabricated devices. Despite promising preclinical results, the translation of these material-based strategies into clinical practice necessitates further research and optimization.

Multifaceted regulatory mechanisms of the EGR family in tumours and prospects for therapeutic applications (Review)

The early growth response (EGR) family comprises four zinc finger transcription factors: EGR1, EGR2, EGR3 and EGR4. These transcription factors belong to the Cys2‑His2‑type zinc finger protein family and are essential in cell differentiation, proliferation, apoptosis and stress response. Initially, EGR1 was recognised for its essential regulatory role in tumourigenesis. Recent studies have identified similarities between other members of the EGR family and EGR1 in tumour regulation and the multifaceted regulatory mechanism employed by the EGR family to affect tumours. Therefore, the present review describes the dual roles of the EGR family in tumours and their regulatory mechanisms in immunity, metabolism and differentiation. Additionally, the present review offers a new perspective on relevant tumour therapeutic studies based on current EGR targeting.

Myeloid cells in the microenvironment of brain metastases

Brain metastasis (BrM) from peripheral solid tumors has a high mortality rate and remains a daunting clinical challenge. In addition to the targeting of tumor cells, studies have focused on the regulation of the tumor microenvironment (TME) for BrM treatment. Here, through a review of recent studies, we revealed that myeloid infiltration is a common feature of the TME in BrMs from different primary sites even though the brain is regarded as an immune-privileged site and is always in an immunosuppressive state. Tumor-educated bone marrow progenitors, especially mesenchymal stem cells (MSCs), may impact the brain tropism and and phenotypic switching of myeloid cells. Additionally, chronic inflammation may be key factors regulating the immunosuppressive TME and myeloid cell reprogramming. Here, the role of myeloid cells in the formation of the TME and strategies for targeting these cells before and after BrM are reviewed, emphasizing the potential for the use of myeloid cells in BrM treatment. However, the direct relationship between the neuronal system and myeloid cell filtration is still unclear and worthy of further study.

Neuro-astrocytic network in breast cancer brain metastases: Adaptive mechanisms and novel therapeutic targets

Breast cancer brain metastases (BrM) are a common and fatal complication in advanced breast cancer patients, with the intricate brain microenvironment significantly limiting the efficacy of current therapeutic strategies. Recently, the neuro-astrocytic network, as a core component of the brain metastasis microenvironment, has garnered extensive attention for its pivotal role in supporting tumor adaptive growth. This review systematically outlines the adaptive mechanisms of the neuro-astrocytic network in BrM, including bidirectional interactions between tumor cells, neurons, and astrocytes, and their profound effects on synapse-like signaling, metabolic pathways, and regulatory networks. Furthermore, we integrate recent advancements in exploring therapeutic targets and discuss potential intervention strategies against tumor-microenvironment interactions and associated challenges. Future research focusing on the multi-target collaborative mechanisms within this network and its clinical translational potential may provide new avenues for precise treatment of BrM.

Circular RNAs in glioma progression: Fundamental mechanisms and therapeutic potential: A review

Gliomas are the most common primary malignant brain tumors, characterized by aggressive invasion, limited therapeutic options, and poor prognosis. Despite advances in surgery, radiotherapy, and chemotherapy, the median survival of glioma patients remains disappointingly low. Therefore, identifying glioma-associated therapeutic targets and biomarkers is of significant clinical importance. Circular RNAs (circRNAs) are a class of naturally occurring long non-coding RNAs (lncRNAs), notable for their stability and evolutionary conservation. Increasing evidence indicates that circRNA expression is dysregulated in gliomas compared to adjacent non-tumor tissues and contributes to the regulation of glioma-related biological processes. Furthermore, numerous circRNAs function as oncogenes or tumor suppressors, mediating glioma initiation, progression, and resistance to temozolomide (TMZ). Mechanistically, circRNAs regulate glioma biology through diverse pathways, including acting as miRNA sponges, binding RNA-binding proteins (RBPs), modulating transcription, and even encoding functional peptides. These features highlight the potential of circRNAs as diagnostic and prognostic biomarkers, as well as therapeutic targets for glioma. This review summarizes the dysregulation and functions of circRNAs in glioma and explores key mechanisms through which they mediate tumor progression, including DNA damage repair, programmed cell death (PCD), angiogenesis, and metabolic reprogramming. Our aim is to provide a comprehensive perspective on the multifaceted roles of circRNAs in glioma and to highlight their potential for translational application in targeted therapy.

KCNE3 Facilitates M1 Macrophage Polarization by Suppressing the Wnt/β-Catenin Pathway, Inhibiting Glioma Proliferation, Migration, and Invasion

The glioma microenvironment is critical for tumor growth, where reprogramming M2-polarized tumor-associated macrophages/microglia (TAMs) to an antitumor M1 phenotype represents a promising therapeutic strategy. While the potassium channel regulatory subunit KCNE3 has been implicated in tumorigenesis across malignancies, its functional role in shaping the glioma microenvironment remains undefined. Here, we leveraged transcriptome data from the Gene Expression Omnibus (GEO) to identify KCNE3 as a TAM-enriched gene in gliomas. To interrogate its mechanistic contributions, we generated KCNE3-knockdown and overexpressing macrophages and evaluated their impact on glioma cells in coculture systems. Silencing KCNE3 in macrophages significantly attenuated glioma cell proliferation, migration, and invasion in vitro, accompanied by enhanced M1 polarization. Mechanistically, KCNE3 depletion suppressed Wnt/β-catenin signaling, driving increased secretion of pro-inflammatory cytokines TNF-α, IL-6, and IL-12. Conversely, KCNE3 overexpression reversed these effects, promoting M2-like characteristics and tumor-supportive behaviors. These findings establish KCNE3 as a key modulator of TAM phenotype and glioma progression, suggesting that targeted KCNE3 inhibition may disarm pro-tumorigenic immune responses to improve therapeutic outcomes. This study uncovers a novel actionable method in glioma immunotherapy.

Unveiling the multifaceted functions of TRIM proteins in glioma pathogenesis

Gliomas, the most prevalent malignant primary brain tumors in adults, represent a heterogeneous group of neoplasms characterized by poor prognosis and limited therapeutic options, particularly in high-grade cases. Understanding the molecular mechanisms underlying glioma pathogenesis is crucial for developing novel and effective treatment strategies. In recent years, increasing attention has been directed toward the tripartite motif (TRIM) family of proteins, a class of E3 ubiquitin ligases, due to their significant roles in glioma development and progression. This review comprehensively explores the diverse functions of TRIM proteins in gliomas, including their expression patterns, prognostic significance, and mechanisms of action that are both ubiquitination-dependent and -independent. By synthesizing current knowledge, we aim to elucidate the role of TRIM proteins in glioma pathogenesis and identify potential therapeutic targets within this protein family.

Knockdown of STK39 inhibits lung cancer brain metastasis by suppressing the CPSF4/NFκB/COX2 pathway

PURPOSE

Lung cancer is the most common cancer worldwide, and approximately 30% of lung cancer patients will develop brain metastases. Serine/threonine kinase 39 (STK39) plays a significant role in various malignancies. However, the role and mechanism of STK39 in lung cancer brain metastasis have not been reported.

METHODS

The expression levels of STK39 in lung cancer cells were detected using quantitative reverse transcription PCR (RT-qPCR) and Western blotting. STK39 expression was knocked down in lung cancer cell lines PC9 and H1299 using RNA interference. Cell proliferation, apoptosis, cell cycle, migration, and invasion abilities were assessed using the CCK-8 assay, colony formation assay, flow cytometry, and Transwell chamber assay, respectively. Phosphoproteomics analysis was performed to identify phosphorylated target proteins of STK39 and associated signaling pathways. PC9 and H1299 cells with knocked-down STK39 were injected into nude mice via the common carotid artery to observe the formation of brain metastases. Finally, RT-qPCR and Western blotting were used to detect the expression of STK39, CPSF4/NFκB/COX2, and epithelial-mesenchymal transition (EMT) markers in lung cancer and brain metastasis tissues, and to analyze the correlation between STK39 expression and the size of metastatic tumors.

RESULTS

STK39 was highly expressed in lung cancer cell lines PC9 and H1299. Knockdown of STK39 inhibited proliferation, migration, and invasion of lung cancer cells, induced apoptosis, and caused cell cycle arrest. Phosphoproteomics and Phos-tag analyses showed that knockdown of STK39 significantly downregulated the expression of phosphorylated CPSF4 protein in PC9 and H1299 cells, along with significant downregulation of NFκB, COX2, and EMT markers. Knockdown of STK39 inhibited the formation of brain metastases by PC9 and H1299 cells in nude mice. Lung cancer brain metastasis tissues exhibited high expression of STK39, CPSF4, NFκB, and COX2, with their expression levels showing a significant positive correlation with the size of metastatic tumors.

CONCLUSION

STK39 is highly expressed in lung cancer brain metastasis tissues, and knockdown of STK39 significantly inhibits brain metastasis in experimental models, accompanied by the suppression of the CPSF4/NFκB/COX2 signaling pathway and EMT process. Therefore, STK39 may be a key factor promoting lung cancer brain metastasis and a potential therapeutic target.

Photoimmuno-Lure Nanoplatform for Enhancing T Cell Expansion in Glioblastoma via Synergistic Treatment of Photodynamic Therapy and Immune Checkpoint Inhibition

The immunosuppressive tumor microenvironment (TME) of glioblastoma (GBM) limits the efficacy of immune checkpoint inhibitors (ICI), primarily due to the absence of cytotoxic T (Tc) cells. In this study, a photoimmuno-lure nanoplatform is presented that combines amphiphilic photosensitizers (PSs) with Atezolizumab leading to the modulation of the TME of GBM and improvement of the therapeutic efficacy through synergistic photodynamic therapy (PDT). The amphiphilic PSs exhibited four-fold higher GBM specificity, superior photostability, and enhanced singlet oxygen generation efficiency (1O2ΦΔ: 0.92) compared to conventional PSs. In in vitro GBM cell lines, amphiphilic PSs increased immune activation cytokines and improved ICI responsiveness compared to single ICI treatment. In addition, similar results are acquired in a GBM 3D spheroid model, showing significantly elevated Tc cell activation. In orthotopic in vivo GBM model, the nanoplatform achieved a 100% survival rate for up to 60 days. Immunological analysis revealed each 2.36-fold, 4.19-fold increase in activated dendritic cells and Tc cells respectively, and significant reductions in MDSCs (0.48-fold) and regulatory T cells (0.5-fold). As a result, this study demonstrates the potential of the synergistic photoimmuno-lure nanoplatform as a clinical solution to overcome the immunosuppressive TME of GBM and activate innate and adaptive immunity for effective treatment.

Integrating multi-omics data to identify the role of Aggrephagy-related genes in tumor microenvironment and key tumorigenesis factors of GB from the perspective of single-cell sequencing

This study presents a pioneering exploration into the role of aggrephagy-related genes (ARGs) in glioblastoma (GB), a kind of malignant tumor which is highly invasive and resistant to a series of therapy. Utilizing single-cell sequencing to dissect their influence on the tumor microenvironment (TME) and tumorigenesis. By applying non-negative matrix factorization for dimensionality reduction and clustering of single-cell data, distinct cellular subtypes within the TME influenced by ARGs were identified, uncovering their functions and interactions. The investigation extends to validating the prognostic significance of ARGs and their potential in predicting immunotherapy outcomes. Molecular docking analysis of key ARGs further highlights TUBA1C and UBB as promising therapeutic targets, offering novel insights into GB's complex biology and suggesting a targeted approach for therapy, which is characterized by some crucial pathways in our analysis, including PI3k-akt and TGF-beta pathways. This comprehensive single-cell level examination not only advances our understanding of aggrephagy's role in GB but also proposes new avenues for prognosis and treatment strategies, emphasizing the critical impact of ARGs on the TME and GB progression.

O-GlcNAcylation stabilized WTAP promotes GBM malignant progression in an N6-methyladenosine-dependent manner

BACKGROUND

Interactions between mesenchymal glioblastoma stem cells (MES GSCs) and myeloid-derived macrophages (MDMs) shape the tumor-immunosuppressive microenvironment (TIME), promoting the progression of glioblastoma (GBM). N6-methyladenosine (m6A) plays important roles in the tumor progression. However, the mechanism of m6A in shaping the TIME of GBM remains elusive.

METHODS

Single-cell RNA sequencing and bulk RNA-seq datasets were employed to identify the critical role of WTAP in interactions between MES GBM and MDMs. The biological function of WTAP was confirmed both in vitro and in vivo. Mechanistically, mass spectrum, RNA immunoprecipitation (RIP), and co-immunoprecipitation assays were conducted.

RESULTS

Here, we identified that m6A methyltransferase Wilms' tumor 1-associated protein (WTAP), whose protein stability could be synergistically enhanced via OGT-mediated O-GlcNAcylation and USP7-mediated de-ubiquitination, promoted LOXL2 m6A modification to enhance its mRNA stabilization in an IGF2BP2-dependent manner, upregulating secretion of LOXL2 protein (sLOXL2). sLOXL2 then interacted with integrin α5β1 on GSCs to activate FAK-ERK signaling, inducing mesenchymal transition of GSCs in an autocrine manner. Meanwhile, sLOXL2 also activated the integrin α5β1-FAK-ERK axis in MDMs, which promoted M2-like MDM phenotypes in a paracrine pathway, thereby contributing to T-cell exhaustion to induce GBM immune escape. In translational medicine, combinations of the OGT inhibitor by targeting WTAP expression and the LOXL2 antagonist by disrupting MES GSC and MDM interactions showed favorable outcomes to the anti-PD1 immunotherapy.

CONCLUSIONS

WTAP plays critical roles in mesenchymal transition of GSCs and formation of TIME, highlighting the therapeutic potential of targeting WTAP and its downstream effectors to enhance the efficacy of immunotherapy.

Repurposing Chemotherapeutics in a Hyaluronic Acid-conjugate Combination Treatment Approach for the Local Immunomodulation of the Glioblastoma Microenvironment

The immunosuppressive tumor immune microenvironment (TIME) renders glioblastoma (GBM) refractory to current chemo-immunotherapeutics. We sought to explore a novel approach for local GBM-associated TIME immunomodulation based on a synergistic combination of the repurposed chemotherapeutic drugs doxorubicin (DOX), which acts to induce immunogenic cell death (ICD) and gemcitabine (GEM), which depletes immunosuppressive myeloid-derived suppressor cells (MDSCs). We conjugated DOX and GEM to hyaluronic acid (HA) to improve efficacy, given this polymer's ability to target CD44 which are overexpressed on cancer cells. The HA-DOX and HA-GEM polymer-drug conjugates provided synergistic cytotoxic effects and maintained ICD-related properties in GBM cells compared to a combination of free drugs. HA-DOX and HA-GEM also reverted the immunosuppressive GBM-associated TIME in orthotopic GL261 tumor-bearing mice by selectively depleting MDSCs and reprogramming M2-like macrophages towards a pro-inflammatory M1-like state, resulting in controlled tumor growth. Local HA-DOX and HA-GEM delivery also increased median survival and controlled tumor growth in an immune refractory SB28-GBM orthotopic mouse GBM model. These findings highlight the potential of repurposing clinically applicable chemotherapeutics in the context of polymer-drug combination treatments for novel immunomodulation strategies in unresectable GBM, which may open new avenues for developing innovative therapies.

Assessing Ecto-5'-Nucleotidase/CD73 Expression and Malignancy Parameters in Early- and Late- Passage C6 Glioma Cells

Glioblastoma (GB) is a highly aggressive tumor characterized by its proliferative and invasive behavior. Ecto-5'-nucleotidase (e5NT/CD73), an enzyme that hydrolyzes extracellular AMP to adenosine, plays a pivotal role in cellular processes and has been involved in tumor progression, with its upregulation observed in several cancers. C6 glioma cells, widely used in GB research, exhibit changes in morphology and biochemical properties, depending on their passage number. This study investigates malignancy-related parameters in early-passage (EPC6) and late-passage (LPC6) C6 cells, highlighting the e5NT/CD73 expression and activity. The results presented here demonstrate that the LPC6 cells showed reduced CD73 expression and lower e5NT/CD73 AMPase activity compared to the EPC6 cells. Despite a higher proliferation rate in the LPC6 cells after two days of growth, Ki67 expression analysis revealed comparable proliferation between the two cell types at 5 and 10 days. Notably, the EPC6 cells showed enhanced proliferation in response to exogenous AMP, whereas the LPC6 cells did not. Furthermore, the EPC6 cells exhibited decreased adhesion but greater colony formation than the LPC6 cells. The LPC6 cells showed a significant reduction in migration, likely due to the loss of e5NT/CD73 migratory function. In the in vivo results, all the rats injected with EPC6 cells developed tumors displaying all the histopathological features of GB, whereas the LPC6 cells formed smaller tumors. Confirming the role performed by e5NT/CD73 in glioma progression, protein silencing significantly reduced tumor growth in vivo. These findings underscore the critical role of purinergic signalling in GB progression and emphasize the need for careful monitoring of passage number and e5NT/CD73 in in vitro experiments.

Complex neural-immune interactions shape glioma immunotherapy

Rich neural-immune interactions in the central nervous system (CNS) shape its function and create a unique immunological microenvironment for immunotherapy in CNS malignancies. Far from the now-debunked concept of CNS "immune privilege," it is now understood that unique immunological niches and constant immune surveillance of the brain contribute in multifaceted ways to brain health and robustly influence immunotherapy approaches for CNS cancers. Challenges include immune-suppressive and neurotoxicity-promoting crosstalk between brain, immune, and tumor cells. Developing effective immunotherapies for cancers of the nervous system will require a deeper understanding of these neural-immune-malignant cell interactions. Here, we review progress and challenges in immunotherapy for gliomas of the brain and spinal cord in light of these unique neural-immune interactions and highlight future work needed to optimize promising immunotherapies for gliomas.

Recent advances in nanomaterial-based brain-targeted delivery systems for glioblastoma therapy

Glioblastoma (GBM) poses a formidable challenge because of its high morbidity and mortality. The therapeutic efficacy of GBM is significantly hampered by the intricate blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). Nanomaterial-based brain-targeted delivery systems have shown great potential for effectively delivering therapeutic agents for GBM treatment by overcoming the limitations of conventional drugs, such as poor BBB penetration, a short half-life, and low bioavailability. This review focuses on an in-depth analysis of the interplay between the BBB/BBTB and drug transport kinetics while analyzing innovative nanoparticle-mediated strategies for enhanced GBM treatment. Moreover, the delivery strategies of nanoparticle-based brain-targeted systems are emphasized, with particular attention given to biomimetic nanoparticles (BMNPs), whose unique advantages. The current challenges, translational potential, and future research directions in this rapidly evolving field are comprehensively discussed, highlighting advances in nanomaterial applications. This review aims to stimulate further research into GBM delivery systems, offering promising avenues for maximizing the therapeutic effects of gene drugs or chemotherapeutic agents in practical applications.

The curse of blood-brain barrier and blood-tumor barrier in malignant brain tumor treatment

The blood-brain barrier (BBB) is crucial for brain homeostasis but is a major obstacle in delivering anticancer drugs to brain tumors. However, this perspective requires re-evaluation, particularly for malignant brain tumors, such as gliomas and brain metastases. In these aggressive tumors, the BBB undergoes significant alterations, leading to the formation of a more permeable blood-tumor barrier. While this increased permeability allows better drug penetration, heterogeneity in blood-tumor barrier (BTB) integrity across different tumor regions remains a challenge. Additionally, the main challenge in treating brain tumors lies not in BBB penetration but in the lack of effective drugs. Conventional chemotherapies, including temozolomide and nitrosourea agents, have shown limited efficacy, and resistance mechanisms often reduce their long-term benefits. The "BBB curse" has often been blamed for the slow progress in drug development. However, emerging evidence suggests that even larger-molecule therapies, such as antibody-drug conjugates, can successfully target brain tumors. This review aims to critically reassess the roles of the BBB and BTB in brain tumor therapy, highlighting their impact on drug delivery and evaluating the current landscape of chemotherapeutic strategies. Furthermore, it explores new approaches to overcome treatment limitations, emphasizing the need for personalized and targeted therapeutic strategies.

Exosome-powered neuropharmaceutics: unlocking the blood-brain barrier for next-gen therapies

BACKGROUND

The blood-brain barrier (BBB) presents a formidable challenge in neuropharmacology, limiting the delivery of therapeutic agents to the brain. Exosomes, nature's nanocarriers, have emerged as a promising solution due to their biocompatibility, low immunogenicity, and innate ability to traverse the BBB. A thorough examination of BBB anatomy and physiology reveals the complexities of neurological drug delivery and underscores the limitations of conventional methods.

MAIN BODY

This review explores the potential of exosome-powered neuropharmaceutics, highlighting their structural and functional properties, biogenesis, and mechanisms of release. Their intrinsic advantages in drug delivery, including enhanced stability and efficient cellular uptake, are discussed in detail. Exosomes naturally overcome BBB barriers through specific translocation mechanisms, making them a compelling vehicle for targeted brain therapies. Advances in engineering strategies, such as genetic and biochemical modifications, drug loading techniques, and specificity enhancement, further bolster their therapeutic potential. Exosome-based approaches hold immense promise for treating a spectrum of neurological disorders, including Alzheimer's, Parkinson's, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), brain tumors, stroke, and psychiatric conditions.

CONCLUSION

By leveraging their innate properties and engineering innovations, exosomes offer a versatile platform for precision neurotherapeutics. Despite their promise, challenges remain in clinical translation, including large-scale production, standardization, and regulatory considerations. Future research directions in exosome nanobiotechnology aim to refine these therapeutic strategies, unlocking new avenues for treating neurological diseases. This review underscores the transformative impact of exosome-based drug delivery, paving the way for next-generation therapies that can effectively penetrate the BBB and revolutionize neuropharmacology.

Identification and characterization of tertiary lymphoid structures in brain metastases

Brain metastases (BrM) are the most common cancers in the brain and linked to poor prognosis. Given the high incidence and often limited treatment options, understanding the complexity of the BrM tumor microenvironment is crucial for the development of novel therapeutic strategies. We performed transcriptome-wide gene expression profiling combined with spatial immune cell profiling to characterize the tumor immune microenvironment in 95 patients with BrM from different primary tumors. We found that BrM from lung carcinoma and malignant melanoma showed overall higher immune cell infiltration as compared to BrM from breast carcinoma. RNA sequencing-based immune cell deconvolution revealed gene expression signatures indicative of tertiary lymphoid structures (TLS) in subsets of BrM, mostly from lung cancer and melanoma. This finding was corroborated by multiplex immunofluorescence staining of immune cells in BrM tissue sections. Detection of TLS signatures was more common in treatment-naïve BrM and associated with prolonged survival after BrM diagnosis in lung cancer patients. Our findings highlight the cellular diversity of the tumor immune microenvironment in BrM of different cancer types and suggest a role of TLS formation for BrM patient outcome.

RETRACTED: Zinc finger Protein207 orchestrates glioma migration through regulation of epithelial-mesenchymal transition

BACKGROUND

Glioma represents the predominant primary malignant brain tumor. For several years, molecular profiling has been instrumental in the management and therapeutic stratification of glioma, providing a deeper understanding of its biological complexity. Accumulating evidence unveils the putative involvement of zinc finger proteins (ZNFs) in cancer. This study aimed to elucidate the role and significance of ZNF207 in glioma.

METHODS

Utilizing online data such as The Cancer Genome Atlas (TCGA), the Chinese Glioma Genome Atlas (CGGA), the Genotype-Tissue Expression (GTEx) project, the Clinical Proteomic Tumor Analysis Consortium (CPTAC), and the Human Protein Atlas (HPA) databases, in conjunction with bioinformatics methodologies including GO, KEGG, GSEA, CIBERSORT immune cell infiltration estimation, and protein-protein interaction (PPI) analysis, enabled a comprehensive exploration of ZNF207's involvement in gliomagenesis. Immunohistochemistry and RT-PCR techniques were employed to validate the expression level of ZNF207 in glioma samples. Subsequently, the biological effects of ZNF207 on glioma cells were explored through in vitro assays.

RESULTS

Our results demonstrate elevated expression of ZNF207 in gliomas, correlating with unfavorable patient outcomes. Stratification analyses were used to delineate the prognostic efficacy of ZNF207 in glioma with different clinicopathological characteristics. Immunocorrelation analysis revealed a significant association between ZNF207 expression and the infiltration levels of T helper cells, macrophages, and natural killer (NK) cells. Utilizing ZNF207 expression and clinical features, we constructed an OS prediction model and displayed well discrimination with a C-index of 0.861. Moreover, the strategic silencing of ZNF207 attenuated glioma cell advancement, evidenced by diminished cellular proliferation, weakened cell tumorigenesis, augmented apoptotic activity, and curtailed migratory capacity alongside the inhibition of the epithelial-mesenchymal transition (EMT) pathway.

CONCLUSIONS

ZNF207 may identify as a prospective biomarker and therapeutic candidate for glioma prevention, providing valuable insights into understanding glioma pathogenesis and treatment strategies.

RNA-Seq Reveals the Mechanism of Synergistic Hydrogen-Chemotherapy Based on Active Magnesium Micromotors for Inhibiting Glioblastoma Recurrence by Modulating Tumor Microenvironment

Postoperative recurrence of glioblastoma (GBM) is a key contributing factor to the unfavorable prognosis of patients. Chemotherapy has been extensively employed as a postoperative treatment for GBM; however, the produced drug resistance significantly undermines the chemotherapeutic efficacy. Herein, a multifunctional system based on magnesium micromotor (Mg-Motor-DOX) is designed and fabricated that can generate hydrogen gas in situ and actively deliver the chemotherapeutic drug doxorubicin (DOX). Utilizing a temperature-sensitive hydrogel, Mg-Motor-DOX is administrated in situ to the residual cavity of the tumor after subtotal GBM resection. The produced H2 by the Mg-water reaction not only propels the motion of motors but also functions as an antioxidant to effectively alleviate the neuroinflammation caused by GBM resection. The H2 bubbles create a pronounced vortex flow in situ, greatly enhancing the DOX penetration and the sensitivity of GBM cells to DOX. Therefore, synergistic hydrogen-chemotherapy significantly inhibits the recurrence of the in situ GBM model. RNA-Seq technology further elucidates the role of the strategy in modulating the tumor immune microenvironment via converting cold tumors into hot tumors, thereby establishing a theoretical foundation for the clinical implementation of synergistic hydrogen-chemotherapy.

Harnessing Immune Rejuvenation: Advances in Overcoming T Cell Senescence and Exhaustion in Cancer Immunotherapy

Immunotherapy has transformed the landscape of cancer treatment, with T cell-based strategies at the forefront of this revolution. However, the durability of these responses is frequently undermined by two intertwined phenomena: T cell exhaustion and senescence. While exhaustion is driven by chronic antigen exposure in the immunosuppressive tumor microenvironment, leading to a reversible state of diminished functionality, senescence reflects a more permanent, age- or stress-induced arrest in cellular proliferation and effector capacity. Together, these processes represent formidable barriers to sustained anti-tumor immunity. In this review, we dissect the molecular underpinnings of T cell exhaustion and senescence, revealing how these dysfunctions synergistically contribute to immune evasion and resistance across a range of solid tumors. We explore cutting-edge therapeutic approaches aimed at rewiring the exhausted and senescent T cell phenotypes. These include advances in immune checkpoint blockade, the engineering of "armored" CAR-T cells, senolytic therapies that selectively eliminate senescent cells, and novel interventions that reinvigorate the immune system's capacity for tumor eradication. By spotlighting emerging strategies that target both exhaustion and senescence, we provide a forward-looking perspective on the potential to harness immune rejuvenation. This comprehensive review outlines the next frontier in cancer immunotherapy: unlocking durable responses by overcoming the immune system's intrinsic aging and exhaustion, ultimately paving the way for transformative therapeutic breakthroughs.

CAR-NK cell therapy combined with checkpoint inhibition induces an NKT cell response in glioblastoma

BACKGROUND

Glioblastoma is the most aggressive primary brain tumor with limited efficacy of established therapies, and a pronounced immunosuppressive tumor microenvironment. Targeting HER2 with local immunotherapy allows for high tumor specificity in the brain with physiologically very low expression. Monotherapy with CAR-NK cells targeted against HER2 has previously shown efficacy in medium-sized GL261/HER2 tumors.

METHODS

Advanced GL261/HER2 tumors were treated by local CAR-NK cell injection combined with systemic anti-PD-1 checkpoint blockade. Tumor growth and survival were monitored. In-depth characterization of the microenvironment was performed by multiplex immune fluorescence, spectral flow cytometry and RNAseq.

RESULTS

Untreated GL261/HER2 tumors were characterized by local immunosuppression and high PD-L1 expression. Combined treatment with NK-92/5.28.z and systemic anti-PD-1 induced robust anti-tumor response and long-term survival. Multiplex immunofluorescence and spectral flow cytometry showed increased CD4+ T cell infiltration in mice treated with CAR-NK cell and anti-PD-1 combination therapy. A cluster of T cells specifically emerging in the combination therapy group expressed markers of NKT cells, which was further verified by immunofluorescence staining.

CONCLUSION

The combination therapy reverted the immunosuppressive tumor microenvironment with increased T and NKT cell infiltration. This resulted in successful treatment of advanced orthotopic tumors refractory to CAR-NK cell monotherapy.

Microfabricated Organ-Specific Models of Tumor Microenvironments

Despite the advances in detection, diagnosis, and treatments, cancer remains a lethal disease, claiming the lives of more than 600,000 people in the United States alone in 2024. To accelerate the development of new therapeutic strategies with improved responses, significant efforts have been made to develop microfabricated in vitro models of tumor microenvironments (TMEs) that address the limitations of animal-based cancer models. These models incorporate several advanced tissue engineering techniques to better reflect the organ- and patient-specific TMEs. Additionally, microfabricated models integrated with next-generation single-cell omics technologies provide unprecedented insights into patient's cellular and molecular heterogeneity and complexity. This review provides an overview of the recent understanding of cancer development and outlines the key TME elements that can be captured in microfabricated models to enhance their physiological relevance. We highlight the recent advances in microfabricated cancer models that reflect the unique characteristics of their organs of origin or sites of dissemination.

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.

7aaRGD - a novel SPP1/integrin signaling-blocking peptide reverses immunosuppression and improves anti-PD-1 immunotherapy outcomes in experimental gliomas

BACKGROUND

Immune checkpoint inhibitors (ICIs) present clinical benefits in many cancer patients but invariably fail in glioblastoma (GBM), the most common and deadly primary brain tumor. The lack of ICIs efficacy in GBM is attributed to the accumulation of tumor-reprogrammed glioma-associated myeloid cells (GAMs) that create a "cold" immunosuppressive tumor microenvironment (TME), impeding the infiltration and activation of effector T cells. GBM-derived αvβ3/αvβ5-integrin ligands, including SPP1, were shown to mediate the emergence of GAMs. We hypothesized that a combination strategy aiming to block the reprogramming of GAMs using a synthetic 7aaRGD peptide that targets SPP1/integrin signaling might overcome resistance to ICIs and reinvigorate anti-tumor immunity.

METHODS

Matrigel invasion assay was used to test the efficacy of 7aaRGD in glioma-microglia co-cultures. We determined the impact of 7aaRGD, administered as a monotherapy or combined with PD-1 blockade, on tumor growth, GAMs accumulation and phenotypes, arginase-1 levels and neovasculature in experimental gliomas. The effects of treatments on the tumor immune landscape were dissected using multiparameter flow cytometry, immunocytochemistry, cytokine profiling and RNA-seq analysis of sorted GAMs followed by CITE-seq based data deconvolution.

RESULTS

7aaRGD efficiently blocked microglia-dependent invasion of human and mouse glioma cells in vitro. Intratumorally delivered 7aaRGD alone did not reduce tumor growth in orthotopic gliomas but prevented the emergence of immunosuppressive GAMs and led to normalization of peritumoral blood vessels. Combining 7aaRGD with anti-PD-1 antibody resulted in reduced tumor growth, with an increase in the number of proliferating, interferon-ɣ producing CD8+T cells and depletion of regulatory T cells. Transcriptomic profiles of myeloid cells were altered by the combined treatment, reflecting the restored "hot" inflammatory TME and boosted immunotherapy responses. Intratumoral administration of 7aaRGD similarly modified the phenotypes of GAMs in human U87-MG gliomas in immunocompromised mice. Exploration of transcriptomic datasets revealed that high expression of integrin receptor coding genes in pre-treatment biopsies was associated with a poorer response to immune check-point blockade in patients with several types of cancers.

CONCLUSIONS

We demonstrate that combining the blockade of SPP1/integrin signaling with ICIs modifies innate immunity and reinvigorates adaptive antitumor responses, which paves the way to improve immunotherapy outcomes in GBM.

ADCYAP1 as a pan-solid cancer biomarker: predictor of immunotherapy efficacy in bladder cancer and prognostic potential across solid tumors

BACKGROUND

ADCYAP1 has been identified with potential effects ranging from tumor growth activation to inhibition. However, it remains unknown whether ADCYAP1 plays a substantial role across pan-cancer.

METHODS

The potential roles of ADCYAP1 in 33 different tumors were analyzed based on The Cancer Genome Atlas (TCGA). We investigated the expression levels, mutations, survival rates, DNA methylation, and immune cell infiltration associated with ADCYAP1. In addition, we analyzed immunotherapy response data from the Tumor Immunotherapy Gene Expression Resource (TIGER) database and previously reported studies.

RESULTS

In general, high expression of ADCYAP1 has been linked to poor OS in the TCGA Bladder urothelial carcinoma cohort (BLCA) (p = 0.003), Stomach adenocarcinoma (STAD) cohort (p = 0.002), and Uterine corpus endometrial carcinoma (UCEC) cohort (p = 0.032). However, the opposite association was observed in the Adrenocortical carcinoma (ACC) cohort (p = 0.034), Kidney renal clear cell carcinoma (KIRC) cohort (p < 0.0001), and Liver hepatocellular carcinoma (LIHC) cohort (p = 0.027). Notably, the BLCA and UCEC samples showed a higher frequency of ADCYAP1 mutations compared to others. Our results suggested that the level of ADCYAP1 methylation can serve as a prognostic factor for OS in patients with STAD and UCEC. The analysis of six cancer immunotherapy(CIT) response datasets showed that ADCYAP1 has predictive value for immunotherapy response in BLCA.

CONCLUSIONS

There is a potential correlation between ADCYAP1 and tumor immunity. Consequently, we propose that ADCYAP1 could potentially serve as a valuable prognostic biomarker for BLCA.

Advances in stem cell-based therapeutic transfers for glioblastoma treatment

INTRODUCTION

Glioblastoma (GBM), a highly malignant brain tumor, has a poor prognosis despite standard treatments like surgery, chemotherapy, and radiation. Glioblastoma stem cells (GSCs) play a critical role in recurrence and therapy resistance. Stem cell-based therapies have emerged as innovative approaches, leveraging the tumor-targeting abilities of stem cells to deliver treatments directly to GBM.

AREAS COVERED

This review focuses on using intact stem cells or subtypes for GBM therapy, excluding antigenic characteristics. The stem cell-based therapies explored include neural, mesenchymal, glioblastoma, hematopoietic and adipose-derived stem cells that have been investigated in both clinical and preclinical settings. A systematic search in PubMed, EMBASE, ClinicalTrials.gov, and Scopus had identified research up until January 2024. Key mechanisms reviewed include immune modulation, angiogenesis inhibition, and apoptosis induction. Discussion of completed and ongoing trials include emphasis on safety, efficacy, challenges, and study design limitations.

EXPERT OPINION

Stem cell-based therapies hold promise for treating GBM by targeting GSCs and improving treatment outcomes. Despite some potential advantages, challenges such as tumorigenesis risks, delivery complexities, and sustained therapeutic effects persist. Future research should prioritize optimizing stem cell modifications, combining them with current treatments, and conducting large-scale trials to ensure safety and efficacy. Integrating stem cell therapies into GBM treatment could provide more effective and less invasive options for patients.

Kinin B1 Receptor Agonist Enhances Blood-Brain Barrier Permeability in Healthy and Glioblastoma Environments

Background/Objectives: The low permeability of the blood-brain barrier (BBB) represents a significant challenge to effective systemic chemotherapy for primary and metastatic brain cancers. Kinin receptors play a crucial role in modulating BBB permeability, and their agonist analogs have been explored in preclinical animal models to enhance drug delivery to the brain. In this study, we investigated whether des-Arg9-bradykinin (DBK), a physiological agonist of kinin B1 receptor (B1R), acts as a brain drug delivery adjuvant by promoting the transient opening of the BBB. Methods: Human brain microvascular endothelial cells (HBMECs) were treated with DBK in the culture medium and in conditioned media from glioblastoma cell lines, namely T98G (CMT98G) and U87MG (CMU87). Immunofluorescence, RT-qPCR, in-cell Western assay, and proximity ligation assay (PLA) were performed to analyze BBB components, kinin receptors and TLR4, a receptor associated with the kinin pathway and inflammation. The effect of DBK on enhancing paracellular molecule transport was evaluated using Evans blue dye (EB) quantification in a cell culture insert assay and in an in vivo model, where mice with and without brain tumors were treated with DBK. To assess the functional impact of the transient BBB opening induced by DBK, the chemotherapeutic drug doxorubicin (DOX) was administered. Results: Treatment with DBK facilitates the presence of EB in the brain parenchyma by transiently disrupting the BBB, as further evidenced by the increased paracellular passage of the dye in an in vitro assay. B1R activation by DBK induces transient BBB opening lasting less than 48 h, enhancing the bioavailability of the DOX within the brain parenchyma and glioma tumor mass. The interaction between B1R and TLR4 is disrupted by the secreted factors released by glioblastoma cells, as conditioned media from T98G and U87 reduce TLR4 staining in endothelial cells without affecting B1R expression. Conclusions: These results further support the potential of B1R activation as a strategy to enhance targeted drug delivery to the brain.

Tumor-associated macrophages correlate with better outcome in SHH medulloblastoma

Objective

Tumor-associated macrophages (TAMs) constitute a significant proportion of the immune cell population within brain tumors. The polarization of macrophages exerts an important influence on the tumor microenvironment (TME). Nevertheless, the specific role of TAMs in sonic hedgehog (SHH) medulloblastoma remains unclear. To investigate the polarization characteristics and effects of TAMs in SHH medulloblastoma, we evaluated the infiltration of M1 and M2 macrophages in SHH medulloblastoma tissues and analyzed the correlation between TAMs recruitment and the clinical outcome of SHH medulloblastoma patients.

Methods

We enrolled a total of 42 patients diagnosed with SHH medulloblastoma. Using multiple immunofluorescence staining on paraffin-embedded sections, we detected the activated phenotype (M1/M2) by monoclonal antibodies for CD68, HLA-DR and CD163. Subsequently, we analyzed the correlation between TAMs and clinical characteristics as well as prognostic factors.

Results

The median age of 42 patients (31 boys, 11 girls) was 5.3 years (range: 0.8-15.1 years). All patients had confirmed pathological types, including 4 cases of classic medulloblastoma (CMB), 33 cases of desmoplastic/nodular medulloblastoma (DNMB), 3 cases of medulloblastoma with extensive nodularity (MBEN), and 2 cases of large-cell/anaplastic medulloblastoma (LCA). Thirteen cases presented with metastasis at diagnosis, while twenty-nine cases were without metastasis. Four cases had high-risk genetic abnormalities. Different proportions of macrophages were found in the collected medulloblastoma tissues, and large amounts of CD68+HLA-DR+CD163+ cells were found. The study revealed that Mtotal (total macrophages) and Mmix (CD68+HLA-DR+CD163+ cells) were significantly higher in group of patients <5 years old (P < 0.05), and Mtotal in non-metastatic group were significantly higher than that in metastatic group (P = 0.043). M2 macrophages in CMB group were significantly higher than that in DNMB/MBEN group (P = 0.036), M1 macrophages were significantly higher in children without high-risk genetic abnormalities (P = 0.007). Five-year PFS was significantly poorer in patients ≥5 years old and metastatic group (P < 0.05). High Mtotal group had a better 5-year PFS (P = 0.000), whereas high M2 group had both better 5-year PFS and OS (P = 0.001, P = 0.001). Multivariate analysis showed that Mtotal and M2 macrophages were independent prognostic factors for 5-year PFS, and M2 macrophages were an independent prognostic factor for 5-year OS.

Conclusion

The increase in total macrophages and M2 macrophages predicts a better outcome of SHH medulloblastoma. TAMs especially M2 macrophages might be a therapeutic target for SHH medulloblastoma.

Combination of Sodium Butyrate and Immunotherapy in Glioma: regulation of immunologically hot and cold tumors via gut microbiota and metabolites

Background

Recent studies have highlighted the importance of cross-talk along the gut-brain axis in regulating inflammatory nociception, inflammatory responses, and immune homeostasis. The gut microbiota, particularly its bacterial composition, plays a crucial role in the development and function of the immune system. Moreover, metabolites produced by the gut microbiota can significantly impact both systemic immune responses and central nervous system (CNS) immunity. Sodium butyrate is a key metabolite produced by the gut microbiota and, as a histone deacetylase inhibitor, can enhance the anti-tumor immunity of cytotoxic CD8+ T cells. However, it remains unclear whether sodium butyrate treatment can enhance the efficacy of PD-1 blockade in glioma therapy. In this research, the effect and underlying mechanism of combination of gut microbiota metabolites and anti-mouse PD-1 mAb on glioma has been investigated.

Methods

RNA-seq assay in glioma cell and biomedical databases, including ONCOMINE, GEPIA and TCGA were incorporated. Subsequently, the inhibitory effect of sodium butyrate on glioma cells and its related mechanisms were assessed through Counting Kit-8 (CCK-8), Flow Cytometry, Western blot (WB), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and other in vitro experiments. In vitro, an orthotopic mouse glioma model was established. MRI imaging, Immunohistochemistry, and Immune cell flow cytometry were used to investigate the therapeutic effects of combined sodium butyrate and PD-1 inhibitor treatment on glioma-bearing mice.

Results

We discovered that deacetylation-associated gene expression is significantly increased in glioma patients and affects patient survival time. Moreover, we found sodium butyrate promoted glioma cell apoptosis, disrupted the cell cycle, and inhibited tumor growth. Additionally, sodium butyrate may upregulate PD-L1 expression in glioma cells by modulating the PI3K/AKT pathway. The experimental results demonstrated that this combination therapy significantly reduced tumor volume and prolonged survival in an orthotopic murine glioma model. Moreover, combination therapy led to an increase in the proportion of probiotic bacteria in the mouse gut microbiota, resulting in elevated levels of antitumor metabolites and a decrease in metabolites that affect immune cell function.

Integrated single cell and bulk RNA sequencing analyses reveal the impact of tryptophan metabolism on prognosis and immunotherapy in colon cancer

Tryptophan metabolism is intricately associated with the progression of colon cancer. This research endeavored to meticulously analyze tryptophan metabolic characteristics in colon cancer and forecast immunotherapy responses. This study analyzed colon cancer samples from a training cohort of 473 tumors and 41 normal tissues from TCGA, with validation in 902 cancer patients across multiple GEO datasets. Patients were stratified into subtypes through consistent clustering, and a tryptophan metabolic risk score model was constructed using the random forest algorithm. Based on these risk scores, patients were delineated into high and low-risk groups, and their clinicopathologic characteristics, immune cell infiltration, immune checkpoint expression, and signaling pathway disparities were examined. The Oncopredict algorithm facilitated the identification of sensitive chemotherapeutic agents, while the immune escape score was employed to evaluate the immunotherapy response across risk groups. Transcriptomic sequencing findings were corroborated by single-cell sequencing from Shanghai Ruijin Hospital. Two distinct subtypes of colon cancer patients emerged, exhibiting significant prognostic and immune cell infiltration differences. The high-risk group demonstrated a poorer prognosis (p < 0.001), advanced clinical stage (p < 0.001), and elevated immunosuppressive cell expression (p < 0.05). Additionally, three chemotherapeutic drugs showed efficacy in the high-risk cohort, displaying a heightened immune escape potential (p < 0.05) and diminished response to immunotherapy. Single-cell sequencing validated the overexpression of tryptophan-related genes in epithelial cells. In conclusion, tryptophan metabolism significantly influences the colon cancer immune microenvironment, with high-risk patients experiencing adverse prognoses and potentially reduced efficacy of immunotherapy.

Single-cell atlas of endothelial and mural cells across primary and metastatic brain tumors

Central nervous system (CNS) malignancies include primary tumors, such as gliomas, and brain metastases (BrMs) originating from diverse extracranial cancers. The blood-brain barrier (BBB) is a key structural component of both primary and metastatic brain cancers. Here, we comprehensively analyzed the two major BBB cell types, endothelial and mural cells, across non-tumor brain tissue, isocitrate dehydrogenase (IDH) mutant (IDH mut) low-grade gliomas, IDH wild-type (IDH WT) high-grade glioblastomas (GBMs), and BrMs from various primary tumors. Bulk and single-cell RNA sequencing, integrated with spatial analyses, revealed that GBMs, but not low-grade gliomas, exhibit significant alterations in the tumor vasculature, including the emergence of diverse pathological vascular cell subtypes. However, these alterations are less pronounced in GBMs than in BrMs. Notably, the BrM vasculature shows higher permeability and more extensive interactions with distinct immune cell populations. This vascular atlas presents a resource toward understanding of tumor-specific vascular features in the brain, providing a foundation for developing vascular- and immune-targeting therapies.

Single-cell transcriptomics reveals immunosuppressive microenvironment and highlights tumor-promoting macrophage cells in Glioblastoma

Glioblastoma (GBM) is the most prevalent and aggressive primary brain malignancy in adults. Nevertheless, the cellular heterogeneity and complexity within the GBM microenvironment (TME) are still not fully understood, posing a significant obstacle in the advancement of more efficient immunotherapies for GBM. In this study, we conducted an integrated analysis of 48 tumor fragments from 24 GBM patients at the single-cell level, uncovering substantial molecular diversity within immune infiltrates. We characterized molecular signatures for five distinct tumor-associated macrophages (TAMs) subtypes. Notably, the TAM_MRC1 subtype displayed a pronounced M2 polarization signature. Additionally, we identified a subtype of natural killer (NK) cells, designated CD56dim_DNAJB1. This subtype is characterized by an exhausted phenotype, evidenced by an elevated stress signature and enrichment in the PD-L1/PD-1 checkpoint pathway. Our findings also highlight significant cell-cell interactions among malignant glioma cells, TAM, and NK cells within the TME. Overall, this research sheds light on the functional heterogeneity of glioma and immune cells in the TME, providing potential targets for therapeutic intervention in this immunologically cold cancer.

Development of a fully human glioblastoma-in-brain-spheroid model for accelerated translational research

INTRODUCTION

Glioblastoma (GBM) progression and therapeutic resistance are significantly influenced by complex interactions between tumor cells and the brain microenvironment, particularly neurons. However, studying these interactions in physiologically relevant conditions has remained challenging due to limitations in existing model systems.

OBJECTIVES

Here, we present hGliCS (human glioma-cortical spheroid), a novel fully human brain tumor model that overcomes key limitations of current approaches by combining patient-derived GBM cells with mature human cortical neurons derived from induced pluripotent stem cells.

RESULTS

We demonstrate that GBM cells in hGliCS develop three critical hallmark features observed in patients: (i) formation of tumor microtubes enabling intercellular communication, (ii) establishment of neuron-glioma synapses, and (iii) development of an interconnected network with coordinated calcium signaling. Single-cell RNA sequencing reveals that tumor cells in hGliCS exhibit cellular heterogeneity and transcriptional profiles remarkably similar to those observed in mouse xenografts, including activation of key oncogenic pathways and neuronal-like features. Notably, while GBM cells showed substantial transcriptional adaptation to the neural environment, neurons maintained their core identity with only subtle alterations in glutamate signaling and structural gene expression. We validate hGliCS as a drug screening platform by demonstrating resistance patterns to standard chemotherapy and radiation similar to clinical observations. Furthermore, we show the model's utility in testing standard and novel therapeutic compounds targeting cell proliferation and tumor-specific neurobiological features, respectively.

CONCLUSION

This physiologically relevant human model system provides new opportunities for studying GBM biology and tumor-neuron interactions in a controlled environment. By bridging the gap between simplified in vitro systems and complex in vivo models, hGliCS represents a promising platform for therapeutic development and personalized medicine approaches in GBM treatment.

Targeting ARPC1B Overcomes Immune Checkpoint Inhibitor Resistance in Glioblastoma by Reversing Protumorigenic Macrophage Polarization

Immunotherapy has elicited significant improvements in outcomes for patients with several tumor types. However, the immunosuppressive microenvironment in glioblastoma (GBM) restricts the therapeutic efficacy of immune checkpoint blockade (ICB). In this study, we investigated the components of the immune microenvironment that contribute to ICB failure in GBM to elucidate the underlying causes of immunotherapeutic resistance. Macrophages were identified as a main contributor to ICB resistance. Expression of actin-related protein 2/3 complex subunit 1B (ARPC1B), a regulatory subunit of the Arp2/3 complex, was elevated in GBM and correlated with macrophage enrichment and prognosis. ARPC1B in tumor cells increased STAT1 expression and subsequent IL10 production, which induced a protumorigenic macrophage state. Mechanistically, ARPC1B inhibited the ubiquitination and degradation of STAT1 by preventing the E3 ubiquitin ligase NEDD4L from binding to STAT1 and by supporting the interaction between STAT1 and the deubiquitinase USP7. Inhibiting ARPC1B reshaped the immunosuppressive microenvironment and increased the efficacy of ICB in GBM models. This study highlights the important role of ARPC1B in macrophage-mediated immunosuppression and proposes a combination treatment regimen for GBM immunotherapy. Significance: ARPC1B induces macrophage-mediated immunosuppression by activating a STAT1/IL10 axis and can be targeted to improve the efficacy of immune checkpoint blockade in glioblastoma.

Plasma-Derived Exosomal i-tRF-LeuCAA as Biomarker for Glioma Diagnosis and Promoter of Epithelial-Mesenchymal Transition via TPM4 Regulation

AIMS

This study aimed to discover plasma-derived exosomal tsRNAs that serve as novel diagnostic biomarkers for glioma and to investigate the mechanism by which tsRNAs regulate glioma development.

METHODS

Differentially expressed tsRNAs in the plasma exosomes of glioma patients were identified using small RNA array sequencing. Bioinformatics analyses were used to predict the biological function of tsRNAs. The changes in the phenotypes of glioma cells treated with a tsRNA mimic and inhibitor were detected. The diagnostic and prognostic characteristics of potential target genes and their related functions in gliomas were further analyzed. The cell and animal experiments were used to analyze the molecular mechanisms.

RESULTS

Among the 453 differentially expressed tsRNAs identified in the plasma-derived exosomes of glioma patients using small RNA sequencing, i-tRF-LeuCAA was associated with the prognosis and molecular diagnostic characteristics of glioma patients and promoted the migration, invasion, and proliferation of glioma cells and inhibited their apoptosis. In addition, TPM4 is a potential target of i-tRF-LeuCAA and is related to epithelial-mesenchymal transition in gliomas.

CONCLUSIONS

i-tRF-LeuCAA could be served as a non-invasive biomarker in the diagnosis and prognosis of glioma. i-tRF-LeuCAA may indirectly regulate TPM4 expression and influence epithelial-mesenchymal transition, which may promote glioma progression.

Analysis of Long Noncoding RNA in Fatty Acid Metabolism to Identify Prognostic Markers and Predict Immunotherapy Response in Low-Grade Glioma

BACKGROUND

Low-grade gliomas (LGGs) are notorious for their difficult early-stage diagnosis, limited treatment options, and poor prognosis, making them a focal point in cancer research. Long noncoding RNAs (lncRNAs) have been identified as regulators of metabolic reprogramming in tumor cells, offering new directions for LGG treatment.

METHODS

This study employed data from The Cancer Genome Atlas, focusing on key fatty acid metabolism-related lncRNA. A risk scoring model was developed using univariate/multifactorial and least absolute shrinkage and selection operator Cox regression. Additionally, the study evaluated the role of these prognostic lncRNAs in LGG progression by assessing associations between LGG immune markers and tumor drug resistance. Finally, functional enrichment analysis highlighted the molecular roles of these lncRNAs.

RESULTS

In this study, a total of 14 prognostic lncRNAs were obtained. The risk model demonstrated excellent validity and reliability, making it a superior predictor of prognosis among patients with varying LGG risks. Among the identified lncRNAs, GHET-1 was notably associated with LGG sensitivity to current chemotherapy options and might be a crucial lncRNA affecting LGG progression. High-risk patients exhibited T-helper cell-mediated immunosuppression, potentially paving new paths for future LGG immunotherapy.

CONCLUSIONS

Focusing on lncRNA regulation and fatty acid metabolism reprogramming, this study established an innovative prognostic prediction model for LGGs, showing outstanding validity and reliability. The findings offer new molecular and cellular targets for the future development of LGG treatments.

Therapeutic Targets in Glioblastoma: Molecular Pathways, Emerging Strategies, and Future Directions

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, characterized by rapid growth, invasive infiltration into surrounding brain tissue, and resistance to conventional therapies. Despite advancements in surgery, radiotherapy, and chemotherapy, median survival remains approximately 15 months, underscoring the urgent need for innovative treatments. Key considerations informing treatment development include oncogenic genetic and epigenetic alterations that may dually serve as therapeutic targets and facilitate treatment resistance. Various immunotherapeutic strategies have been explored and continue to be refined for their anti-tumor potential. Technical aspects of drug delivery and blood-brain barrier (BBB) penetration have been addressed through novel vehicles and techniques including the incorporation of nanotechnology. Molecular profiling has emerged as an important tool to individualize treatment where applicable, and to identify patient populations with the most drug sensitivity. The goal of this review is to describe the spectrum of potential GBM therapeutic targets, and to provide an overview of key trial outcomes. Altogether, the progress of clinical and preclinical work must be critically evaluated in order to develop therapies for GBM with the strongest therapeutic efficacy.

The local microenvironment suppresses the synergy between irradiation and anti-PD1 therapy in breast-to-brain metastasis

The brain environment is uniquely specialized to protect its neuronal tissue from excessive inflammation by tightly regulating adaptive immunity. However, in the context of brain cancer progression, this regulation can lead to a conflict between T cell activation and suppression. Here, we show that, while CD8+ T cells can infiltrate breast cancer-brain metastases, their anti-tumor cytotoxicity is locally suppressed in the brain. Conversely, CD8+ T cells exhibited tumoricidal activity in extracranial mammary lesions originating from the same cancer cells. Consequently, combined high-dose irradiation and anti-programmed cell death protein 1 (PD1) therapy was effective in extracranial tumors but not intracranial lesions. Transcriptional analyses and functional studies identified neutrophils and Trem2-expressing macrophages as key sources for local T cell suppression within the brain, providing rational targets for future therapeutic strategies.

Temporal dynamics of immune cell transcriptomics in brain metastasis progression influenced by gut microbiome dysbiosis

Interactions between metastatic cancer cells and the brain microenvironment regulate brain metastasis (BrMet) progression. Central nervous system (CNS)-native and peripheral immune cells influence the BrMet immune landscape, but the dynamics and factors modulating this microenvironment remain unclear. As the gut microbiome impacts CNS and peripheral immune activity, we investigated its role in regulating immune response dynamics throughout BrMet stages. Antibiotic-induced (ABX) gut dysbiosis significantly increased BrMet burden versus controls but was equalized with fecal matter transplantation, highlighting microbiome diversity as a regulator of BrMet. Single-cell sequencing revealed a highly dynamic immune landscape during BrMet progression in both conditions. However, the timing of the monocyte inflammatory response was altered. Microglia displayed an elevated activation signature in late-stage metastasis in ABX-treated mice. T cell and microglia perturbation revealed involvement of these cell types in modulating BrMet under gut dysbiosis. These data indicate profound effects on immune response dynamics imposed by gut dysbiosis across BrMet progression.

Opportunities to Modulate Tumor Ecosystem Toward Successful Glioblastoma Immunotherapy

Over the past decade, the failure of multiple clinical trials has confirmed the need for a systematic and comprehensive understanding of glioblastoma (GBM). Current immunotherapies aiming to harness the immune system to achieve anti-tumor effects remain largely ineffective, highlighting the complexities of the GBM microenvironment. However, our recent understanding of immune niches within the central nervous system provides both opportunities and challenges in translating these insights into successful immunotherapy implementation. We discuss these strategies, including targeting multiple antigens within the heterogeneous GBM microenvironment, identifying new druggable targets to abrogate immunosuppression, and understanding niche-specific immune cell functionality to modulate tumor-immune-stroma interactions.

Targeting gut microbiota: a potential therapeutic approach for tumor microenvironment in glioma

Glioma, being one of the malignant tumors with the highest mortality rate globally, has an unclear pathogenesis, and the existing treatment effects still have certain limitations. The tumor microenvironment (TME) plays an important role in the occurrence, development, and recurrence of glioma. As one of the important regulatory factors of TME, the gut microbiota can regulate the progression of glioma not only by interacting with the brain through the brain-gut axis but also by influencing the tumor immune microenvironment (TIME) and inflammatory microenvironment. Recent studies have identified the gut microbiota and TME as potential therapeutic targets for glioma. This paper aims to summarize the role of the gut microbiota in TME, the association between them and glioma, and the potential of developing new intervention measures by targeting the gut microbiota. Understanding the involvement process of the gut microbiota in glioma may pave the way for the development of effective treatment methods that can regulate TME and prevent disease progression.

Extracellular Vesicles Carrying Tenascin-C are Clinical Biomarkers and Improve Tumor-Derived DNA Analysis in Glioblastoma Patients

Extracellular vesicles (EVs) act as carriers of biological information from tumors to the bloodstream, enabling the detection of circulating tumor material and tracking of disease progression. This is particularly crucial in glioblastoma, a highly aggressive and heterogeneous tumor that is challenging to monitor. Using imaging flow cytometry (IFCM), we conducted an immunophenotyping analysis of eight glioma-associated antigens and tetraspanins in plasma EVs from 37 newly diagnosed glioblastoma patients (pre- and post-surgery), 11 matched individuals with recurrent glioblastoma, and 22 healthy donors (HD). Tenascin-C (TNC) positive EVs displayed the strongest differences in newly diagnosed and recurrent glioblastoma patients, when compared to non-tumor subjects. Among dual-positive subpopulations, TNC+/CD9+ EVs were the most elevated in newly diagnosed (FC = 7.6, p <0.0001, AUC = 81%) and recurrent patients (FC = 16.5, p <0.0001; AUC = 90%) than HD. In comparison with other CNS tumors (n = 25), this subpopulation was also 34.5-fold higher in glioblastoma than in meningioma cases (p <0.01). Additionally, TNC+/CD9+ EV levels were 3.3-fold elevated in cerebrospinal fluid from glioblastoma patients (n = 6) than controls (p <0.05). Aberrant TNC levels were further observed in glioblastoma EVs from different sources and purified via different methods. Immunohistochemical analysis revealed high levels of TNC in tumor tissues. Spatial transcriptomic analysis indicated a TNC overexpression in malignant cell populations of glioblastoma resections, particularly in cells with mesenchymal-like signatures and chromosomal aberrations. Lastly, we purified TNC+ EVs from plasma of 21 glioblastoma patients by magnetic sorting and detected the oncogenic mutation TERT*C228T by droplet digital PCR. The mutant allele frequency was higher in TNC+ EVs vs TNC-negative EVs (FC = 32, p <0.001), total EVs (FC = 5.3, p <0.001) or cell-free DNA (FC = 5.3, p <0.01). In conclusion, circulating TNC+ EVs may have potential as clinical biomarkers in glioblastoma, and their purification could improve the identification of tumor-specific mutations in liquid biopsies.

A novel optimized orthotopic mouse model for brain metastasis with sustained cerebral blood circulation and capability of multiple delivery

Brain metastasis is thought to be related to the high mortality and poor prognosis of lung cancer. Despite significant advances in the treatment of primary lung cancer, the unique microenvironment of the brain renders current therapeutic strategies largely ineffective against brain metastasis. The lack of effective drugs for brain metastasis treatment is primarily due to the incomplete understanding of the mechanisms underlying its initiation and progression. Currently, our understanding of brain metastasis remains limited, primarily due to the absence of appropriate models that can realistically simulate the entire process of tumor cell detachment from the primary site, circulation through the bloodstream, and eventual colonization of the brain. Therefore, there is a pressing need to develop more suitable lung cancer brain metastasis models that can effectively replicate these critical stages of metastasis. Here, based on the traditional carotid artery injection model, we established a novel orthotopic mouse model by using a light-controlled hydrogel to repair the puncture site on the carotid artery, with sustained cerebral blood circulation and the capability of multiple delivery cancer cell to mimic lung cancer brain metastasis. The optimized orthotopic mouse model significantly reduced cerebral ischemia and improved cerebral oxygenation by 60% compared to the traditional orthotopic mouse model, enhancing post-operative survival rates. It also showed a reduction in pro-inflammatory cytokines and featured less inflammatory and more resting states of microglial and astrocyte cells. Furthermore, the optimized orthotopic mouse model markedly increased the success rate and absolute number of the metastatic clones in the brain. Additionally, the multiple delivery model based on the optimized orthotopic mouse model substantially augmented the tumor clone number and formation rates compared to single injection in the optimized orthotopic mouse model. This model overcomes previous limitations by maintaining cerebral circulation, providing a more accurate simulation of the continuous entry of tumor cells into cerebral circulation. It offers a robust platform for studying the interactions of cancer cells with the brain microenvironment and testing new therapeutic approaches.

Effects of Induced Pluripotent Stem Cell-Derived Astrocytes on Cisplatin Sensitivity in Pediatric Brain Cancer Cells

Background: ATRTs and DIPGs are deadly pediatric brain tumors with poor prognosis. These tumors can develop resistance to chemotherapies, which may be significantly influenced by their microenvironment. Since astrocytes are the most abundant glial cell type in the brain microenvironment and may support tumor growth and chemoresistance, this study investigated the effects of induced pluripotent stem cell-derived astrocytes (iPSC-astrocytes) on cisplatin sensitivity in CHLA-05-ATRT and SF8628 (DIPG) cells. iPSCs provide an unlimited and standardized source of nascent astrocytes, which enables modeling the interaction between childhood brain tumor cells and iPSC-astrocytes within a controlled coculture system. Methods: To study the effects on tumor growth, the iPSC-astrocytes were cocultured with tumor cells. Additionally, the tumor cells were exposed to various concentrations of cisplatin to evaluate their chemosensitivity in the presence of astrocytes. Results: The paracrine interaction of iPSC-astrocytes with tumor cells upregulated astrocyte activation markers GFAP and STAT3 and promoted tumor cell proliferation. Moreover, the cisplatin treatment significantly decreased the viability of CHLA-05-ATRT and SF8628 cells. However, tumor cells exhibited reduced sensitivity to cisplatin in the coculture with iPSC-astrocytes. During cisplatin treatment, DIPG cells in particular showed upregulation of resistance markers, ERK1, STAT3, and MTDH, which are associated with enhanced proliferation and invasion. They also had increased expression of APEX1, which is involved in the base excision repair pathway following cisplatin-induced DNA damage. Conclusion: These findings underscore the significance of the tumor microenvironment in modulating tumor cell survival and chemosensitivity.

Myeloid Cells Induce Infiltration and Activation of B Cells and CD4+ T Follicular Helper Cells to Sensitize Brain Metastases to Combination Immunotherapy

Brain metastasis is a poor prognostic factor in patients with cancer. Despite showing efficacy in many extracranial tumors, immunotherapy with anti-PD-1 mAb or anti-CTLA4 mAb seems to be less effective against intracranial tumors. Promisingly, recent clinical studies have reported that combination therapy with anti-PD-1 and anti-CTLA4 mAbs has a potent antitumor effect on brain metastasis, highlighting the need to elucidate the detailed mechanisms controlling the intracranial tumor microenvironment (TME) to develop effective immunotherapeutic strategies. In this study, we analyzed the tumor-infiltrating lymphocytes in murine models of brain metastasis that responded to anti-CTLA4 and anti-PD-1 mAbs. Activated CD4+ T follicular helper (TFH) cells with high CTLA4 expression characteristically infiltrated the intracranial TME, which were activated by combination anti-CTLA4 and anti-PD-1 treatment. The loss of TFH cells suppressed the additive effect of CTLA4 blockade on anti-PD-1 mAb. B-cell-activating factor belonging to the TNF family (BAFF) and a proliferation-inducing ligand (APRIL) produced by abundant myeloid cells, particularly CD80hiCD206lo proinflammatory M1-like macrophages, in the intracranial TME induced B-cell and TFH-cell infiltration and activation. Furthermore, the intracranial TME of patients with non-small cell lung cancer featured TFH- and B-cell infiltration as tertiary lymphoid structures. Together, these findings provide insights into the immune cell cross-talk in the intracranial TME that facilitates an additive antitumor effect of CTLA4 blockade with anti-PD-1 treatment, supporting the potential of a combination immunotherapeutic strategy for brain metastases. Significance: B-cell and CD4+ T follicular helper cell activation via BAFF/APRIL from abundant myeloid cells in the intracranial tumor microenvironment enables a combinatorial effect of CTLA4 and PD-1 blockade in brain metastases.

Targeting CHEK2-YBX1&YBX3 regulatory hub to potentiate immune checkpoint blockade response in gliomas

Although GBM's immunosuppressive environment is well known, the tumor's resistance to CD8+ T cell killing is not fully understood. Our previous study identified Checkpoint Kinase 2 (Chek2) as the key driver of CD8+ T cell resistance in mouse glioma through an in vivo CRISPR screen and demonstrated that Chk2 inhibition, combined with PD-1/PD-L1 blockade, significantly enhanced CD8+ T cell-mediated tumor killing and improved survival in preclinical model. Here, we aimed to elucidate the immunosuppressive function of Chek2. Immunoprecipitation (IP) followed by mass spectrometry (MS) and phosphoproteomics identified an association between Chek2 with the DNA/RNA-binding proteins YBX1 and YBX3 that are implicated in transcriptional repression of pro-inflammatory genes. Single-gene knock-out and overexpression studies of CHEK2, YBX1, and YBX3 in multiple glioma cell lines revealed that these proteins positively regulate each other's expression. RNA sequencing coupled with chromatin immunoprecipitation-sequencing (ChIP-seq) analysis demonstrated common inflammatory genes repressed by CHK2-YBX1&YBX3 hub. Targeting one of the hub proteins, YBX1, with the YBX1 inhibitor SU056 led to degradation of CHK2-YBX1&YBX3 hub. Targeting of this hub by SU056 led to enhanced antigen presentation and antigen specific CD8+ T cell proliferation. Further, combination of SU056 with ICB significantly improved survival in multiple glioma models. Collectively, these findings reveal an immunosuppressive mechanism mediated by the CHK2-YBX1&YBX3 hub proteins. Therefore, CHK2-YBX1&YBX3 hub targeting in combination with immune checkpoint blockade therapies in gliomas is warranted.

Glioblastoma Tumor Microenvironment and Purinergic Signaling: Implications for Novel Therapies

Glial-origin brain tumors, particularly glioblastomas (GBMs), are known for their devastating prognosis and are characterized by rapid progression and fatal outcomes. Despite advances in surgical resection, complete removal of the tumor remains unattainable, with residual cells driving recurrence that is resistant to conventional therapies. The GBM tumor microenviroment (TME) significantly impacts tumor progression and treatment response. In this review, we explore the emerging role of purinergic signaling, especially the P2X7 receptor (P2X7R). Due to its unique characteristics, it plays a key role in tumor progression and offers a potential therapeutic strategy for GBM through TME modulation. We discuss also the emerging role of the P2X4 receptor (P2X4R) as a promising therapeutic target. Overall, targeting purinergic signaling offers a potential approach to overcoming current GBM treatment limitations.

Characterization of immune microenvironment associated with medulloblastoma metastasis based on explainable machine learning

Importance

Medulloblastoma (MB) is the most common malignant brain tumor in children, with metastasis being the primary cause of recurrence and mortality. The tumor microenvironment (TME) plays a critical role in driving metastasis; however, the mechanisms underlying TME alterations in MB metastasis remain poorly understood.

Objective

To develop and validate machine learning (ML) models for predicting patient outcomes in MB and to investigate the role of TME components, particularly immune cells and immunoregulatory molecules, in metastasis.

Methods

ML models were constructed and validated to predict prognosis and metastasis in MB patients. Eight algorithms were evaluated, and the optimal model was selected. Lasso regression was employed for feature selection, and SHapley Additive exPlanations values were used to interpret the contribution of individual features to model predictions. Immune cell infiltration in tumor tissues was quantified using the microenvironment cell populations-counter method, and immunohistochemistry was applied to analyze the expression and distribution of specific proteins in tumor tissues.

Results

The ML models identified metastasis as the strongest predictor of poor prognosis in MB patients, with significantly worse survival outcomes observed in metastatic cases. High infiltration of CD8+ T cells and cytotoxic T lymphocytes (CTLs), along with elevated expression of the TGFB1 gene encoding transforming growth factor beta 1 (TGF-β1), were strongly associated with metastasis. Independent transcriptomic and immunohistochemical analyses confirmed significantly higher CD8+ T cell/CTL infiltration and TGF-β1 expression in metastatic compared to nonmetastatic MB samples. Patients with both high CD8+ T cell/CTL infiltration and elevated TGFB1 expression in the context of metastasis exhibited significantly worse survival outcomes compared to patients with low expression and no metastasis.

Interpretation

This study identifies metastasis as the key prognostic factor in MB and reveals the pivotal roles of CD8+ T cells, CTLs, and TGF-β1 within the TME in promoting metastasis and poor outcomes. These findings provide a foundation for developing future therapeutic strategies targeting the TME to improve MB patient outcomes.