Mesenchymal differentiation mediated by NF-κB promotes radiation resistance in glioblastoma

Decoding glioblastoma's diversity: Are neurons part of the game?

Glioblastoma multiforme (GBM, WHO Grade 4) is a highly aggressive primary brain tumor with limited treatment options and a poor prognosis. A key challenge in GBM therapy lies in its pronounced heterogeneity, both within individual tumors (intratumoral) and between patients (intertumoral). Historically, neurons have been underexplored in GBM research; however, recent studies reveal that GBM development is closely linked to neural and glial progenitors, often mimicking neurodevelopmental processes in a dysregulated manner. Beyond damaging neuronal tissue, GBM actively engages with neurons to promote pro-tumorigenic signaling, including neuronal hyperexcitability and seizures. Single-cell RNA sequencing (scRNA-seq) has revolutionized our understanding of the tumor microenvironment (TME), uncovering the critical roles of immune cells, endothelial cells, and astrocytes in tumor progression. However, technical limitations of scRNA-seq hinder its ability to capture the transcriptomes of neurons, necessitating the use of single-nucleus RNA sequencing (snRNA-seq) to study these interactions at single-cell resolution. This work collects the emerging insights of glioblastoma-neuron interactions, focusing on how GBM exploits neurodevelopmental pathways and reshapes neuronal networks. Moreover, we perform bioinformatic analysis of publicly available snRNA-seq datasets to propose putative cell-cell interactions driving glioma-neuronal dynamics. This study delineates key signaling pathways and underscores the need for further investigation to evaluate their potential as therapeutic targets.

Glioblastoma multiforme: an updated overview of temozolomide resistance mechanisms and strategies to overcome resistance

Glioblastoma (GBM) is an aggressive primary brain tumor with high lethality. The typical treatment regimen includes post-surgical radiotherapy and temozolomide (TMZ) chemotherapy, which helps extend survival. Nevertheless, TMZ resistance occurs in approximately 50% of patients. This resistance is primarily associated with the expression of O6-methylguanine-DNA methyltransferase (MGMT), which repairs O6-methylguanine lesions generated by TMZ and is thought to be the major mechanism of drug resistance. Additionally, the mismatch repair and base excision repair pathways play crucial roles in TMZ resistance. Emerging studies also point to drug transport mechanisms, glioma stem cells, and the heterogeneous tumor microenvironment as additional influences on TMZ resistance in gliomas. A better understanding of these mechanisms is vital for developing new treatments to improve TMZ effectiveness, such as DNA repair inhibitors, inhibitors of multidrug transporting proteins, TMZ analogs, and combination therapies targeting multiple pathways. This article discusses the main resistance mechanisms and potential strategies to counteract resistance in GBM patients, aiming to broaden the understanding of these mechanisms for future research and to explore the therapeutic effects of traditional Chinese medicines and their active components in overcoming TMZ resistance.

KAT5 regulates neurodevelopmental states associated with G0-like populations in glioblastoma

Quiescence cancer stem-like cells may play key roles in promoting tumor cell heterogeneity and recurrence for many tumors, including glioblastoma (GBM). Here we show that the protein acetyltransferase KAT5 is a key regulator of transcriptional, epigenetic, and proliferative heterogeneity impacting transitions into G0-like states in GBM. KAT5 activity suppresses the emergence of quiescent subpopulations with neurodevelopmental progenitor characteristics, while promoting GBM stem-like cell (GSC) self-renewal through coordinately regulating E2F- and MYC- transcriptional networks with protein translation. KAT5 inactivation significantly decreases tumor progression and invasive behavior while increasing survival after standard of care. Further, increasing MYC expression in human neural stem cells stimulates KAT5 activity and protein translation, as well as confers sensitivity to homoharringtonine, to similar levels to those found in GSCs and high-grade gliomas. These results suggest that the dynamic behavior of KAT5 plays key roles in G0 ingress/egress, adoption of quasi-neurodevelopmental states, and aggressive tumor growth in gliomas.

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.

Assessing the diagnostic, prognostic, and therapeutic potential of the somatostatin/cortistatin system in glioblastoma

Glioblastoma remains an incurable tumour (median survival: ~ 15 months) and little clinical progress has been made over the past decades. Therefore, identification of novel biomarkers and therapeutic targets is imperative. Targeting the somatostatin/cortistatin-system is considered a successful avenue for treating different tumour pathologies. Thus, we comprehensively characterized (clinically and molecularly) the expression of the somatostatin/cortistatin-system components [ligands and receptors (SSTRs)] using five cohorts of patients and tested the in-vitro therapeutic response of different SSTR-agonists and somatostatin analogs (SSAs) in primary patient-derived glioblastoma cells. A clear downregulation of the whole somatostatin/cortistatin-system (except for SSTR5) in glioblastoma vs. non-tumour brain samples was demonstrated, with high discriminatory capacity. Moreover, poor overall-survival and critical aggressiveness-parameters (i.e., recurrence, IDH1-wildtype and G-CIMP status, classical and mesenchymal GBM-subtypes, EGFR-amplification) were robustly associated with SSTR1/SSTR2 downregulation. Notably, octreotide, pasireotide, and SSTR1/2/5-agonists treatments significantly reduced cell-proliferation in primary patient-derived GBM-cells. Molecularly, antitumour effects of octreotide/pasireotide were exerted through key signalling-factors related to glioblastoma-aggressiveness (i.e., CDKN1A-B/JAK-STAT/NF-κB/TGF-β-pathways). Altogether, this study demonstrated that somatostatin/cortistatin-system is drastically altered in GBM representing a useful prognostic tool, and that SSTR-modulators might represent a potential therapeutic strategy to treat specific subsets of patients with GBM.

Synthetic lethality through Gsk3β inhibition in glioma stem cells via the WNT-WWC1-YAP axis

Glioblastoma (GBM) is an aggressive brain tumor driven by glioma stem cells (GSCs), which contribute to tumor growth and therapeutic resistance. This study investigates the effects of Gsk3β inhibition on GSC viability, focusing on the role of the canonical WNT signaling pathway. We found that Gsk3β inhibition activates the WNT pathway, leading to upregulation of Wwc1, which downregulates Yap via Lats1 phosphorylation. This reduces GSC proliferation, self-renewal, and enhances chemosensitivity. Analysis of clinical datasets revealed that WNT pathway activation correlates with improved prognosis in proneural gliomas, particularly in IDH1-mutated tumors. Our findings suggest that targeting the WNT-WWC1-YAP axis, particularly through Gsk3β inhibition, could induce synthetic lethality in GSCs and provide a promising therapeutic strategy for gliomas. These results highlight the potential of exploiting WNT-induced synthetic lethality as a novel approach for glioma treatment.

p21-Dependent Senescence Induction by BMP4 Renders Glioblastoma Cells Vulnerable to Senolytics

Glioblastoma (GBM) is a highly malignant brain tumor with extensive cellular heterogeneity and plasticity. Bone morphogenetic protein 4 (BMP4) has shown potential as a therapeutic agent by promoting differentiation, but its effects are complex and context dependent. While BMP4's role in differentiation is well established, its impact on senescence remains unclear. This study investigates BMP4's ability to induce senescence in GBM cells. Primary GBM cultures were treated with BMP4 and analyzed for senescence markers, including cell enlargement, p21 expression, senescence-related gene enrichment, and senescence-associated-β-galactosidase activity. A p21 knockout model was used to determine its role in BMP4-induced senescence, and sensitivity to the senolytic agent navitoclax was evaluated. BMP4 induced senescence in the GBM cultures, particularly in mesenchymal (MES)-like GBM cells with high baseline p21 levels. The knockout of p21 nearly abolished BMP4-induced senescence, maintaining cell size and proliferation. Furthermore, navitoclax effectively eliminated BMP4-induced senescent cells through apoptosis, while sparing cells with normal p21 expression. Our findings highlight BMP4 as an inducer of p21-dependent senescence in GBM, particularly in MES-like cells. This study clarifies BMP4's dual roles in differentiation and senescence, emphasizing their context dependence. Given the strong link between MES-like cells and therapy resistance, their heightened susceptibility to senescence may aid in developing targeted therapies for GBM and potentially other cancers with similar cellular dynamics.

Cell death in glioblastoma and the central nervous system

Glioblastoma is the commonest and deadliest primary brain tumor. Glioblastoma is characterized by significant intra- and inter-tumoral heterogeneity, resistance to treatment and dismal prognoses despite decades of research in understanding its biological underpinnings. Encompassed within this heterogeneity and therapy resistance are severely dysregulated programmed cell death pathways. Glioblastomas recapitulate many neurodevelopmental and neural injury responses; in addition, glioblastoma cells are composed of multiple different transformed versions of CNS cell types. To obtain a greater understanding of the features underlying cell death regulation in glioblastoma, it is important to understand the control of cell death within the healthy CNS during homeostatic and neurodegenerative conditions. Herein, we review apoptotic control within neural stem cells, astrocytes, oligodendrocytes and neurons and compare them to glioblastoma apoptotic control. Specific focus is paid to the Inhibitor of Apoptosis proteins, which play key roles in neuroinflammation, CNS cell survival and gliomagenesis. This review will help in understanding glioblastoma as a transformed version of a heterogeneous organ composed of multiple varied cell types performing different functions and possessing different means of apoptotic control. Further, this review will help in developing more glioblastoma-specific treatment approaches and will better inform treatments looking at more direct brain delivery of therapeutic agents.

Inflammatory reprogramming of the solid tumor microenvironment by infiltrating clonal hematopoiesis is associated with adverse outcomes

Clonal hematopoiesis (CH)-the expansion of somatically mutated hematopoietic cells-is common in solid cancers. CH is associated with systemic inflammation, but its impact on tumor biology is underexplored. Here, we report the effects of CH on the tumor microenvironment (TME) using 1,550 treatment-naive patient samples from the Clinical Proteomics Tumor Analysis Consortium (CPTAC) cohort. CH is present in 18.3% of patients, with one-third of CH mutations also detectable in tumor-derived DNA from the same individual (CH-Tum), reflecting CH-mutant leukocyte infiltration. Across cancers, the presence of CH-Tum is associated with worse survival outcomes. Molecular analyses reveal an association between CH-Tum and an immune-rich, inflammatory TME that is notably distinct from age-related gene expression changes. These effects are most prominent in glioblastoma, where CH correlates with pronounced macrophage infiltration, inflammation, and an aggressive, mesenchymal phenotype. Our findings demonstrate that CH shapes the TME, with potential applications as a biomarker in precision oncology.

The epigenetic mechanisms involved in the treatment resistance of glioblastoma

Glioblastoma (GBM) is an aggressive malignant brain tumor with almost inevitable recurrence despite multimodal management with surgical resection and radio-chemotherapy. While several genetic, proteomic, cellular, and anatomic factors interplay to drive recurrence and promote treatment resistance, the epigenetic component remains among the most versatile and heterogeneous of these factors. Herein, the epigenetic landscape of GBM refers to a myriad of modifications and processes that can alter gene expression without altering the genetic code of cancer cells. These processes encompass DNA methylation, histone modification, chromatin remodeling, and non-coding RNA molecules, all of which have been found to be implicated in augmenting the tumor's aggressive behavior and driving its resistance to therapeutics. This review aims to delve into the underlying interactions that mediate this role for each of these epigenetic components. Further, it discusses the two-way relationship between epigenetic modifications and tumor heterogeneity and plasticity, which are crucial to effectively treat GBM. Finally, we build on the previous characterization of epigenetic modifications and interactions to explore specific targets that have been investigated for the development of promising therapeutic agents.

The translatome of glioblastoma

Glioblastoma (GB), the most common and aggressive brain tumor, demonstrates intrinsic resistance to current therapies, resulting in poor clinical outcomes. Cancer progression can be partially attributed to the deregulation of protein translation mechanisms that drive cancer cell growth. In this study, we present the translatome landscape of GB as a valuable data resource. Eight patient-derived GB sphere cultures (GSCs) were analyzed using ribosome profiling and messenger RNA (mRNA) sequencing. We investigated inter-cell-line differences through differential expression analysis at both the translatome and transcriptome levels. Translational changes post-radiotherapy were assessed at 30 and 60 min. The translation of non-coding RNAs (ncRNAs) was validated using in-house and public mass spectrometry (MS) data, whereas RNA expression was confirmed by quantitative PCR (qPCR). Our findings demonstrate that ribosome sequencing provides more detailed information than MS or transcriptional analyses. Transcriptional similarities among GSCs correlate with translational similarities, aligning with previously defined subtypes such as proneural and mesenchymal. Additionally, we identified a broad spectrum of open reading frame types in both coding and non-coding mRNA regions, including long non-coding RNAs (lncRNAs) and pseudogenes undergoing active translation. Translation of ncRNAs into peptides was independently confirmed by in-house data and external MS data. We also observed that translational regulation of histones (downregulated) and splicing factors (upregulated) occurs in response to radiotherapy. These data offer new insights into genome-wide protein synthesis, identifying translationally regulated genes and alternative translation initiation sites in GB under normal and radiotherapeutic conditions, providing a rich resource for GB research. Further functional validation of differentially expressed genes after radiotherapy is needed. Understanding translational control in GB can reveal mechanistic insights and identify currently unknown biomarkers, ultimately enhancing the diagnosis and treatment of this aggressive brain cancer.

GNE-317 Reverses MSN-Mediated Proneural-to-Mesenchymal Transition and Suppresses Chemoradiotherapy Resistance in Glioblastoma via PI3K/mTOR

Glioblastoma (GBM) resistance to chemoradiotherapy is a major factor contributing to poor treatment outcomes. This resistance markedly affects the effectiveness of surgery combined with chemoradiotherapy and leads to post-surgical tumor recurrence. Therefore, exploring the mechanisms underlying chemoradiotherapy resistance in GBM is crucial for understanding its progression and improving therapeutic options. This study found that moesin (MSN) acts as a key promotor of chemoradiotherapy resistance in glioma stem cells (GSCs), enhancing their proliferation and stemness maintenance. Mechanistically, MSN activates the downstream PI3K/mTOR signaling pathway, driving the proneural-to-mesenchymal transition (PMT) in GSCs. This process enhances the repair of DNA damage caused by radiotherapy (RT) and temozolomide (TMZ), thereby increasing the resistance of GSCs to chemoradiotherapy. Additionally, GNE-317, a small molecule drug capable of crossing the blood-brain barrier, specifically inhibits MSN and suppresses the activation of downstream PI3K/mTOR signaling. Importantly, the combination of GNE-317 with RT and TMZ exhibits a strong synergistic effect both in vivo and in vitro, achieving better efficacy compared to the traditional combination of RT and TMZ. This study not only advances understanding of the mechanisms underlying chemoradiotherapy resistance in GBM but also provides a promising new approach for enhancing treatment outcomes.

Transcriptomic Regulation by Astrocytic m6A Methylation in the mPFC

Astrocytes, the most prevalent type of glial cells, have been found to play a crucial part in numerous physiological functions. By offering metabolic and structural support, astrocytes are vital for the proper functioning of the brain and regulating information processing and synaptic transmission. Astrocytes located in the medial prefrontal cortex (mPFC) are highly responsive to environmental changes and have been associated with the development of brain disorders. One of the primary mechanisms through which the brain responds to environmental factors is epitranscriptome modification. M6-methyladenosine methylation is the most prevalent internal modification of eukaryotic messenger RNA (mRNA), and it significantly impacts transcript processing and protein synthesis. However, the effects of m6A on astrocyte transcription and function are still not well understood. Our research demonstrates that ALKBH5, an RNA demethylase of m6A found in astrocytes, affects gene expression in the mPFC. These findings suggest that further investigation into the potential role of astrocyte-mediated m6A methylation in the mPFC is warranted.

NUP98-p65 complex regulates DNA repair to maintain glioblastoma stem cells

The nuclear pore complex (NPC) is an evolutionarily conserved structure that maintains the traffic between the nucleus and cytoplasm. Here, we profiled the expression of nucleoporins (NUPs) in glioblastoma stem cells (GSCs) and found that NUP98 promoted GSC maintenance and therapeutic resistance. GSCs preferentially expressed NUP98, which is essential for GSC tumorigenesis in vitro and in vivo. RNA sequencing demonstrated that NUP98 regulated the expression of key DNA damage and repair pathways. NUP98 formed a complex with transcription factor p65 to directly activate genes involved in homologous repair. Attenuation of NUP98 or p65 expression induced unrepaired intrinsic DNA damage and sensitized GSC to ionizing radiation. Clinically, overexpression of NUP98 informs poor clinical outcome among glioblastoma (GBM) patients. Collectively, our results demonstrate that NUP98-p65 represents a novel node in the regulation of DNA repair, suggesting a therapeutic strategy with potential clinical benefits for GBM patients.

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.

EZH2 functional dichotomy in reactive oxygen species-stratified glioblastoma

BACKGROUND

Enhancer of zeste homolog 2 (EZH2), well known for its canonical methyltransferase activity in transcriptional repression in many cancers including glioblastoma (GBM), has an understudied noncanonical function critical for sustained tumor growth. Recent GBM consortial efforts reveal complex molecular heterogeneity for which therapeutic vulnerabilities correlated with subtype stratification remain relatively unexplored. Current enzymatic EZH2 inhibitors (EZH2inh) targeting its canonical su(var)3-9, enhancer-of-zeste and trithorax domain show limited efficacy and lack durable response, suggesting that underlying differences in the noncanonical pathway may yield new knowledge. Here, we unveiled dual roles of the EZH2 CXC domain in therapeutically distinct, reactive oxygen species (ROS)-stratified tumors.

METHODS

We analyzed differentially expressed genes between ROS classes by examining cis-regulatory elements as well as clustering of activities and pathways to identify EZH2 as the key mediator in ROS-stratified cohorts. Pull-down assays and CRISPR knockout of EZH2 domains were used to dissect the distinct functions of EZH2 in ROS-stratified GBM cells. The efficacy of NF-κB-inducing kinase inhibitor (NIKinh) and standard-of-care temozolomide was evaluated using orthotopic patient-derived GBM xenografts.

RESULTS

In ROS(+) tumors, CXC-mediated co-interaction with RelB drives constitutive activation of noncanonical NF-κB2 signaling, sustaining the ROS(+) chemoresistant phenotype. In contrast, in ROS(-) subtypes, Polycomb Repressive Complex 2 methyltransferase activity represses canonical NF-κB. Addressing the lack of EZH2inh targeting its nonmethyltransferase roles, we utilized a brain-penetrant NIKinh that disrupts EZH2-RelB binding, consequently prolonging survival in orthotopic ROS(+)-implanted mice.

CONCLUSIONS

Our findings highlight the functional dichotomy of the EZH2 CXC domain in governing ROS-stratified therapeutic resistance, thereby advocating for the development of therapeutic approaches targeting its noncanonical activities and underscoring the significance of patient stratification methodologies.

STAT3-controlled CHI3L1/SPP1 positive feedback loop demonstrates the spatial heterogeneity and immune characteristics of glioblastoma

Proneural-mesenchymal transition (PMT) is a phenotypic alteration and contributes to the malignant progression of glioblastoma (GBM). Macrophages, as a main infiltrating component of the tumor immune microenvironment (TIM), control the biological processes of PMT; however, the mechanisms driving this process remain largely unknown. Here, the overall landscape of tumor and nontumor cells was described by scMulti-omics technology. Then, we demonstrated that chitinase-3-like protein 1 (CHI3L1) played a critical role in maintaining mesenchymal (MES) status and reprogramming macrophage phenotype using C57BL/6 and NSG mice models derived from PN20 cells. Mechanistically, osteopontin (OPN)/ITGB1 maintained the activation of nuclear factor κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways by establishing a positive feedback loop with the CHI3L1-STAT3 axis, resulting in PMT. CHI3L1 enhanced the phosphorylation, nuclear localization, and transcriptional activity of STAT3 via directly binding its coiled-coil domain (CCD). Importantly, we screened and validated that hygromycin B (HB), an inhibitor of the STAT3-CCD domain, disrupted the CHI3L1-STAT3 interaction, thereby reducing the tumor burden in vitro and in vivo.

Mapping the developmental trajectory of human astrocytes reveals divergence in glioblastoma

Glioblastoma (GBM) is defined by heterogeneous and resilient cell populations that closely reflect neurodevelopmental cell types. Although it is clear that GBM echoes early and immature cell states, identifying the specific developmental programmes disrupted in these tumours has been hindered by a lack of high-resolution trajectories of glial and neuronal lineages. Here we delineate the course of human astrocyte maturation to uncover discrete developmental stages and attributes mirrored by GBM. We generated a transcriptomic and epigenomic map of human astrocyte maturation using cortical organoids maintained in culture for nearly 2 years. Through this approach, we chronicled a multiphase developmental process. Our time course of human astrocyte maturation includes a molecularly distinct intermediate period that serves as a lineage commitment checkpoint upstream of mature quiescence. This intermediate stage acts as a site of developmental deviation separating IDH-wild-type neoplastic astrocyte-lineage cells from quiescent astrocyte populations. Interestingly, IDH1-mutant tumour astrocyte-lineage cells are the exception to this developmental perturbation, where immature properties are suppressed as a result of D-2-hydroxyglutarate oncometabolite exposure. We propose that this defiance is a consequence of IDH1-mutant-associated epigenetic dysregulation, and we identified biased DNA hydroxymethylation (5hmC) in maturation genes as a possible mechanism. Together, this study illustrates a distinct cellular state aberration in GBM astrocyte-lineage cells and presents developmental targets for experimental and therapeutic exploration.

Hypoxia Dependent Inhibition of Glioblastoma Cell Proliferation, Invasion, and Metabolism by the Choline-Kinase Inhibitor JAS239

Background: Elevated choline kinase alpha (ChoK) levels are observed in most solid tumors, including glioblastomas (GBM), and ChoK inhibitors have demonstrated limited efficacy in GBM models. Given that hypoxia is associated with resistance to GBM therapy, we hypothesized that tumor hypoxia could be responsible for the limited response. Therefore, we evaluated the effects of hypoxia on the function of JAS239, a potent ChoK inhibitor in four GBM cell lines. Methods: Rodent (F98 and 9L) and human (U-87 MG and U-251 MG) GBM cell lines were subjected to 72 h of hypoxic conditioning and treated with JAS239 for 24 h. NMR metabolomic measurements and analyses were performed to evaluate the signaling pathways involved. In addition, cell proliferation, cell cycle progression, and cell invasion parameters were measured in 2D cell monolayers as well as in 3D cell spheroids, with or without JAS239 treatment, in normoxic or hypoxic cells to assess the effect of hypoxia on JAS239 function. Results: Hypoxia and JAS239 treatment led to significant changes in the cellular metabolic pathways, specifically the phospholipid and glycolytic pathways, associated with a reduction in cell proliferation via induced cell cycle arrest. Interestingly, JAS239 also impaired GBM invasion. However, effects from JAS239 were variable depending on the cell line, reflecting the inherent heterogeneity of GBMs. Conclusions: Our findings indicate that JAS239 and hypoxia can deregulate cellular metabolism, inhibit cell proliferation, and alter cell invasion. These results may be useful for designing new therapeutic strategies based on ChoK inhibition, which can act on multiple pro-tumorigenic features.

A novel case of glial transdifferentiation in renal medullary carcinoma brain metastasis

Renal medullary carcinoma is a rare undifferentiated tumor of the kidney associated with sickle cell trait and characterized by INI1 (SMARCB1) loss. Although metastasis to lungs, lymph nodes, and bone is commonly reported, distant spread to the central nervous system almost never occurs. Here we present an unusual case of a patient with renal medullary carcinoma with metastasis to the brain following treatment which included tazemetostat, an EZH2 inhibitor. The metastatic brain lesion harbored morphologic, immunohistochemical, and methylation profile supportive of a primary CNS phenotype with loss of the trimethylated lysine 27 residue of histone 3 while maintaining INI1 loss and a specific gene fusion shared with the patient's tumor prior to initiation of tazemetostat therapy. Therefore, given the common genetic signatures in the brain metastasis and the patient's prior tumor, this case represents a rare event of glial transdifferentiation in a brain metastasis of renal medullary carcinoma following the use of an epigenetic modulator. As renal medullary carcinoma has been known to cleverly utilize adaptive mechanisms for survival, we propose that such cell plasticity seen in this case may have been provoked by the use of a drug that alters the epigenetic signature of the tumor cells. Thus, careful assessment of tumor biology following novel therapeutic treatment options must be performed in order to note such unexpected consequences of treatment.

USP14 modulates stem-like properties, tumorigenicity, and radiotherapy resistance in glioblastoma stem cells through stabilization of MST4-phosphorylated ALKBH5

Rationale: Glioblastoma (GBM) is the most aggressive type of primary brain cancer and contains self-renewing GBM stem cells (GSCs) that contribute to tumor growth and therapeutic resistance. However, molecular determinants governing therapeutic resistance of GSCs are poorly understood. Methods: We performed genome-wide analysis of deubiquitylating enzymes (DUBs) in patient-derived GSCs and used gene-specific shRNAs to identify an important DUB gene contributing to GSC survival and radioresistance. Subsequently, we employed mass spectrometry and immunoprecipitation to show the interaction between USP14 and ALKBH5, and identified the upstream kinase MST4, which is essential for the deubiquitylation and stabilization of ALKBH5. Additionally, we performed integrated transcriptome and m6A-seq analyses to uncover the key downstream pathways of ALKBH5 that influence GSC radioresistance. Results: Our study demonstrates the essential role of the deubiquitinase USP14 in maintaining the stemness, tumorigenic potential, and radioresistance of GSCs. USP14 stabilizes the m6A demethylase ALKBH5 by preventing its K48-linked ubiquitination and degradation through HECW2. The phosphorylation of ALKBH5 at serine 64 and 69 by MST4 increases its interaction with USP14, promoting ALKBH5 deubiquitylation. Furthermore, ALKBH5 directly interacts with the USP14 transcript in a manner dependent on YTHDF2, establishing a positive feedback loop that sustains the overexpression of both proteins in GSCs. The MST4-USP14-ALKBH5 signaling pathway is crucial for enhancing stem cell-like traits, facilitating homologous recombination repair of DNA double-strand breaks, and promoting radioresistance and tumorigenicity in GSCs. This signaling cascade is further stimulated in GSCs following exposure to ionizing radiation (IR). Inhibiting USP14 with the small molecule IU1 disrupts ALKBH5 deubiquitylation and increases the effectiveness of IR therapy on GSC-derived brain tumor xenografts. Conclusion: Our results identify the MST4-USP14-ALKBH5 signaling pathway as a promising therapeutic target for treating GBM.

Endothelial-secreted Endocan activates PDGFRA and regulates vascularity and spatial phenotype in glioblastoma

Extensive neovascularization is a hallmark of glioblastoma (GBM). In addition to supplying oxygen and nutrients, vascular endothelial cells provide trophic support to GBM cells via paracrine signaling. Here we report that Endocan (ESM1), an endothelial-secreted proteoglycan, confers enhanced proliferative, migratory, and angiogenic properties to GBM cells and regulates their spatial identity. Mechanistically, Endocan exerts at least part of its functions via direct binding and activation of the PDGFRA receptor. Subsequent downstream signaling enhances chromatin accessibility of the Myc promoter and upregulates Myc expression inducing stable phenotypic changes in GBM cells. Furthermore, Endocan confers radioprotection on GBM cells in vitro and in vivo. Inhibition of Endocan-PDGFRA signaling with ponatinib increases survival in the Esm1 wild-type but not in the Esm1 knock-out mouse GBM model. Our findings identify Endocan and its downstream signaling axis as a potential target to subdue GBM recurrence and highlight the importance of vascular-tumor interactions for GBM development.

Red light-activated depletion of drug-refractory glioblastoma stem cells and chemosensitization of an acquired-resistant mesenchymal phenotype

Glioblastoma stem cells (GSCs) are potent tumor initiators resistant to radiochemotherapy, and this subpopulation is hypothesized to re-populate the tumor milieu due to selection following conventional therapies. Here, we show that 5-aminolevulinic acid (ALA) treatment-a pro-fluorophore used for fluorescence-guided cancer surgery-leads to elevated levels of fluorophore conversion in patient-derived GSC cultures, and subsequent red light-activation induces apoptosis in both intrinsically temozolomide chemotherapy-sensitive and -resistant GSC phenotypes. Red light irradiation of ALA-treated cultures also exhibits the ability to target mesenchymal GSCs (Mes-GSCs) with induced temozolomide resistance. Furthermore, sub-lethal light doses restore Mes-GSC sensitivity to temozolomide, abrogating GSC-acquired chemoresistance. These results suggest that ALA is not only useful for fluorescence-guided glioblastoma tumor resection, but that it also facilitates a GSC drug-resistance agnostic, red light-activated modality to mop up the surgical margins and prime subsequent chemotherapy.

The Slovenian translational platform GlioBank for brain tumor research: Identification of molecular signatures of glioblastoma progression

Background

Glioblastoma (GB) is one of the most lethal solid tumors in humans, with an average patient life expectancy of 15 months and a 5-year survival rate of 5%-10%. GB is still uncurable due to tumor heterogeneity and invasive nature as well as therapy-resistant cancer cells. Centralized biobanks with clinical data and corresponding biological material of GB patients facilitate the development of new treatment approaches and the search for clinically relevant biomarkers, with the goal of improving outcomes for GB patients. The aim of this study was firstly to establish a Slovenian translation platform, GlioBank, and secondly to demonstrate its utility through the identification of molecular signatures associated with GB progression and patient survival.

Methods

GlioBank contains tissue samples and corresponding tumor models as well as clinical data from patients diagnosed with glioma, with a focus on GB. Primary GB cells, glioblastoma stem cells (GSCs), and organoids have been established from fresh tumor biopsies. We performed expression analyses of genes associated with GB progression and bioinformatics analyses of available clinical and research data obtained from a subset of 91 GB patients. qPCR was performed to determine the expression of genes associated with therapy resistance and cancer cell invasion, including markers of different GB subtypes, GSCs, epithelial-to-mesenchymal transition, and immunomodulation/chemokine signaling in tumor tissues and corresponding cellular models.

Results

GlioBank contains biological material and research, and clinical data collected in the SciNote electronic laboratory notebook. To date, more than 240 glioma tissue samples have been collected and stored in GlioBank, most of which are GB tissues (205) and were further processed to establish primary GB cells (n = 64), GSCs (n = 14), and GB organoids (n = 17). Corresponding blood plasma (n = 103) and peripheral blood mononuclear cells (n = 101) are also stored. GB tumors were classified into 4 different subtypes that differed regarding patient survival; the mixed subtype exhibited the longest patient survival. High DAB2, S100A4, and STAT3 expression were associated with poor overall patient survival, and DAB2 was found to be an independent prognostic marker for GB survival. We analyzed the molecular signatures between different tumor regions (core vs. rim). STMN4, ERBB3, and ACSBG1 were upregulated in the tumor rim, suggesting that these genes are associated with the invasive nature of GB.

Conclusions

GlioBank is a centralized biobank that has been built by a multidisciplinary network with the aim of facilitating disease-oriented basic and clinical research. The advantages of GlioBank include the molecular characterization of GB based on targeted gene expression, the availability of diverse cellular models (eg, GB cells and organoids), and a large number of patient-matched tumor core and rim samples, all with accompanying molecular and clinical data. We report here for the first time an association between DAB2 expression and low overall survival in GB patients, indicative of a prognostic value of DAB2.

Protocol for quantifying xenografted human cancer cells in zebrafish larvae using Cellpose

Here, we present a protocol for quantifying xenografted human glioblastoma stem cells (GSCs) in zebrafish larvae. We first describe steps for orthotopic xenotransplantation of GSCs into the midbrain of zebrafish larvae, immunofluorescent labeling, and confocal imaging. We then detail procedures for GSC quantification using the Cellpose algorithm. This protocol provides a technique for the semi-automatic segmentation and quantification of human cancer cells in xenograft experiments. With this approach, cancer cell survival and proliferation can be determined in an unbiased manner.

Single-cell multi-omics analysis reveals candidate therapeutic drugs and key transcription factor specifically for the mesenchymal subtype of glioblastoma

The inherent heterogeneity of tumor cells impedes the development of targeted therapies for specific glioblastoma (GBM) subtypes. This study aims to investigate the mesenchymal subtype of GBM to uncover detailed characteristics, potential therapeutic strategies, and improve precision treatment for GBM patients. We integrated single-cell RNA sequencing (scRNA-seq), single-nucleus assay for transposase-accessible chromatin sequencing (snATAC-seq), and bulk RNA sequencing datasets to identify core gene modules, candidate therapeutic drugs, and key transcription factors specific to mesenchymal subtype GBM tumor cells which we validated in vitro and human samples. Our analysis encompassed a heterogeneous single-cell landscape of 55,845 cells from tumor and adjacent normal tissues, focusing on the mesenchymal subtype's adverse prognosis and its association with hypoxia. We identified a core gene module composed of 38 genes and, through pharmacogenomic analysis, found that Trametinib and Dasatinib exhibit increased effectiveness against mesenchymal subtype GBM cells. Furthermore, by incorporating snATAC-seq data, we delineated a crucial regulatory network and pinpointed the key transcription factor CEBPG. Our research has highlighted the strong link between the mesenchymal-like (MES-like) properties of GBM and hypoxia, providing valuable insights into candidate drugs and pivotal targets for precision treatment of the mesenchymal subtype.

Comprehensive Transcriptomic Analysis Reveals Cell-Type-Specific Roles of Human Odorant Receptors in Glioblastoma and the Tumor Microenvironment

Odorant receptors (ORs), which constitute approximately 50% of all human G protein-coupled receptors, are increasingly recognized for their diverse roles beyond odor perception, including functions in various pathological conditions like brain diseases and cancers. However, the roles of ORs in glioblastoma (GBM), the most aggressive primary brain tumor with a median survival of only 15 months, remain largely unexplored. Here, we performed an integrated transcriptomic analysis combining The Cancer Genome Atlas RNA-seq and single-cell RNA sequencing data from GBM patients to uncover cell-type-specific roles of ORs within the tumor and its microenvironment. Our findings reveal that ORs display distinct expression patterns, with OR51E1 enriched in pericytes linked to vascular remodeling and angiogenesis, OR2B11 associated with tumor-associated macrophages supporting immunosuppressive phenotypes, and OR2L13 correlated with synaptic activity in recurrent tumors, potentially mediating treatment-induced neuronal adaptations. These results highlight ORs as potential therapeutic targets, offering new insights into their regulatory roles in GBM progression, immune modulation, and treatment resistance.

Co-evolution of glioma and immune microenvironment

Glioma evolution is governed by a multitude of dynamic interactions between tumor cells and heterogenous neighboring, non-cancerous cells. This complex ecosystem, termed the tumor microenvironment (TME), includes diverse immune cell types that have gained increasing attention for their critical and paradoxical roles in tumor control and tumorigenesis. Recent work has revealed that the cellular composition and functional state of immune cells in the TME can evolve extensively depending on the tumor stage and intrinsic features of surrounding glioma cells. Concurrently, adaptations to the glioma cellular phenotype, including activation of various cellular states, occur in the context of these immune cell alterations. In this review, we summarize important features of the immune TME that play key roles during each stage of glioma progression, from initiation to immune escape, invasion and recurrence. Understanding the complex interplay between tumor and immune cells is critical for the development of effective immunotherapies for glioma treatment.

Glioblastoma-associated macrophages: A key target in overcoming glioblastoma therapeutic resistance

Glioblastoma multiforme (GBM) is recognized as the most aggressive and malignant form of brain cancer, characterized by a highly heterogeneous phenotype, poor prognosis, and a median survival time of less than 16 months. Recent studies have highlighted the critical role of glioblastoma-associated macrophages (GAMs) in promoting tumor progression and resistance not only to immunotherapy but also to radiotherapy and chemotherapy. GAMs actively suppress immune responses, promote angiogenesis, facilitate tumor metastasis, and induce therapy resistance, through various mechanisms such as cytokines production, signaling pathways regulation, and angiogenesis. In this context, understanding these regulatory mechanisms is essential for developing efficient therapies. Preclinical studies have investigated diverse approaches to target these cells, both as monotherapies or in combination with other treatments. While these approaches have shown promise in strengthening antitumor immune responses in animal models, their clinical success remains to be fully determined. Herein, we provide a comprehensive overview of GAMs's role in GBM therapeutic resistance and summarizes existing approaches to target GAMs in overcoming tumor resistance.

Unravelling the mosaic: Epigenetic diversity in glioblastoma

Glioblastoma is the most common primary malignant brain tumour. Despite decades of intensive research in the disease, its prognosis remains poor, with an average survival of only 14 months after diagnosis. The remarkable level of intra- and interpatient heterogeneity is certainly contributing to the lack of progress in tackling this tumour. Epigenetic dysregulation plays an important role in glioblastoma biology and significantly contributes to intratumour heterogeneity. However, it is becoming increasingly clear that it also contributes to intertumour heterogeneity, which historically had mainly been linked to diverse genetic events occurring in different patients. In this review, we explore how DNA methylation, chromatin remodelling, microRNA (miRNA) dysregulation, and long noncoding RNA (lncRNA) alterations contribute to intertumour heterogeneity in glioblastoma, including its implications for advanced tumour stratification, which is the essential first step for developing more effective patient-specific therapeutic approaches.

FACT inhibitor CBL0137, administered in an optimized schedule, potentiates radiation therapy for glioblastoma by suppressing DNA damage repair

PURPOSE

Standard-of-care for glioblastoma remains surgical debulking followed by temozolomide and radiation. However, many tumors become radio-resistant while radiation damages surrounding brain tissue. Novel therapies are needed to increase the effectiveness of radiation and reduce the required radiation dose. Drug candidate CBL0137 is efficacious against glioblastoma by inhibiting histone chaperone FACT, known to be involved in DNA damage repair. We investigated the combination of CBL0137 and radiation on glioblastoma.

METHODS

In vitro, we combined CBL0137 with radiation on U87MG and A1207 glioblastoma cells using the clonogenic assay to evaluate the response to several treatment regimens, and the Fast Halo Assay to examine DNA repair. In vivo, we used the optimum combination treatment regimen to evaluate the response of orthotopic tumors in nude mice.

RESULTS

In vitro, the combination of CBL0137 and radiation is superior to either alone and administering CBL0137 two hours prior to radiation, having the drug present during and for a prolonged period post-radiation, is an optimal schedule. CBL0137 inhibits DNA damage repair following radiation and affects the subcellular distribution of histone chaperone ATRX, a molecule involved in DNA repair. In vivo, one dose of CBL0137 is efficacious and the combination of CBL0137 with radiation increases median survival over either monotherapy.

CONCLUSIONS

CBL0137 is most effective with radiation for glioblastoma when present at the time of radiation, immediately after and for a prolonged period post-radiation, by inhibiting DNA repair caused by radiation. The combination leads to increased survival making it attractive as a dual therapy.

Hypoxia-driven heterogeneous expression of α5 integrin in glioblastoma stem cells is linked to HIF-2α

Despite numerous molecular targeted therapies tested in glioblastoma (GBM), no significant progress in patient survival has been achieved in the last 20 years in the overall population of GBM patients except with TTfield setup associated with the standard of care chemoradiotherapy. Therapy resistance is associated with target expression heterogeneity and plasticity between tumors and in tumor niches. We focused on α5 integrin implicated in aggressive GBM in preclinical and clinical samples. To address the characteristics of α5 integrin heterogeneity we started with patient data indicating that elevated levels of its mRNA are related to hypoxia pathways. We turned on glioma stem cells which are considered at the apex of tumor formation and recurrence but also as they localize in hypoxic niches. We demonstrated that α5 integrin expression is stem cell line dependent and is modulated positively by hypoxia in vitro. Importantly, heterogeneity of expression is conserved in in vivo stem cell-derived mice xenografts. In hypoxic niches, HIF-2α is preferentially implicated in α5 integrin expression which confers migratory capacity to GBM stem cells. Hence combining HIF-2α and α5 integrin inhibitors resulted in proliferation and migration impairment of α5 integrin expressing cells. Stabilization of HIF-2α is however not sufficient to control integrin α5 expression. Our results show that AHR (aryl hydrocarbon receptor) expression is inversely related to HIF-2α and α5 integrin expressions suggesting a functional competition between the two transcription factors. Collectively, data confirm the high heterogeneity of a GBM therapeutic target, its induction in hypoxic niches by HIF-2α and suggest a new way to attack molecularly defined GBM stem cells.

Targeted reprogramming of tumor-associated macrophages for overcoming glioblastoma resistance to chemotherapy and immunotherapy

The resistance of glioblastoma multiforme (GBM) to standard chemotherapy is primarily attributed to the existence of tumor-associated macrophages (TAMs) in the GBM microenvironment, particularly the anti-inflammatory M2 phenotype. Targeted modulation of M2-TAMs is emerging as a promising strategy to enhance chemotherapeutic efficacy. However, combination TAM-targeted therapy with chemotherapy faces substantial challenges, notably in terms of delivery efficiency and targeting specificity. In this study, we designed a pH-responsive hierarchical brain-targeting micelleplex loaded with temozolomide (TMZ) and resiquimod (R848) for combination chemo-immunotherapy against GBM. This delivery system, termed PCPA&PPM@TR, features a primary Angiopep-2 decoration on the outer layer via a pH-cleavable linker and a secondary mannose analogue (MAN) on the middle layer. This pH-responsive hierarchical targeting strategy enables effective BBB permeability while simultaneous GBM- and TAMs-targeting delivery. GBM-targeted delivery of TMZ induces alkylation and triggers an anti-GBM immune response. Concurrently, TAM-targeted delivery of R848 reprograms their phenotype from M2 to pro-inflammatory M1, thereby diminishing GBM resistance to TMZ and amplifying the immune response. In vivo studies demonstrated that targeted modulation of TAMs using PCPA&PPM@TR significantly enhanced anti-GBM efficacy. In summary, this study proposes a promising brain-targeting delivery system for the targeted modulation of TAMs to combat GBM.

CCN1 Promotes Mesenchymal Phenotype Transition Through Activating NF-κB Signaling Pathway Regulated by S100A8 in Glioma Stem Cells

BACKGROUND

The presence of glioma stem cells (GSCs) and the occurrence of mesenchymal phenotype transition contribute to the miserable prognosis of glioblastoma (GBM). Cellular communication network factor 1 (CCN1) is upregulated within various malignancies and associated with cancer development and progression, while the implications of CCN1 in the phenotype transition and tumorigenicity of GSCs remain unclear.

METHODS

Data for bioinformatic analysis were obtained from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. A range of primary GBM and GSC cell models were then used to demonstrate the regulatory role of CCN1 via the phenotype validation, tumor sphere formation assays, extreme limiting dilution assays (ELDA), and transwell assays. To screen out the downstream signaling pathway, we employed high-throughput RNA-seq. Intracranial xenograft GSC mouse models were used to investigate the role of CCN1 in vivo.

RESULTS

Among the CCN family members, CCN1 was highly expressed in MES-GBM/GSCs and was correlated with a poor prognosis. Both in vitro and in vivo assays indicated that knockdown of CCN1 in MES-GSCs reduced the tumor stemness, proliferation, invasion, and tumorigenicity, whereas CCN1 overexpression in PN-GSCs exhibited the opposite effects. Mechanistically, CCN1 triggered the FAK/STAT3 signaling in autocrine and paracrine manners to upregulate the expression of S100A8. Knockdown of S100A8 inactivated NF-κB/p65 pathway and significantly suppressed the tumorigenesis of MES-GSCs.

CONCLUSION

Our findings reveal that CCN1 may be an important factor in the enhanced invasiveness and MES phenotype transition of GSCs and highlight the potential to target CCN1 for treating GBM.

Microglia induce an interferon-stimulated gene expression profile in glioblastoma and increase glioblastoma resistance to temozolomide

AIMS

Glioblastoma is the most malignant primary brain tumour. Even with standard treatment comprising surgery followed by radiation and concomitant temozolomide (TMZ) chemotherapy, glioblastoma remains incurable. Almost all patients with glioblastoma relapse owing to various intrinsic and extrinsic resistance mechanisms of the tumour cells. Glioblastomas are densely infiltrated with tumour-associated microglia and macrophages (TAMs). These immune cells affect the tumour cells in experimental studies and are associated with poor patient survival in clinical studies. The aim of the study was to investigate the impact of microglia on glioblastoma chemo-resistance.

METHODS

We co-cultured patient-derived glioblastoma spheroids with microglia at different TMZ concentrations and analysed cell death. In addition, we used RNA sequencing to explore differentially expressed genes after co-culture. Immunostaining was used for validation.

RESULTS

Co-culture experiments showed that microglia significantly increased TMZ resistance in glioblastoma cells. RNA sequencing revealed upregulation of a clear interferon-stimulated gene (ISG) expression signature in the glioblastoma cells after co-culture with microglia, including genes such as IFI6, IFI27, BST2, MX1 and STAT1. This ISG expression signature is linked to STAT1 signalling, which was confirmed by immunostaining. The ISG expression profile observed in glioblastoma cells with enhanced TMZ resistance corresponded to the interferon-related DNA damage resistance signature (IRDS) described in different solid cancers.

CONCLUSIONS

Here, we show that the IRDS signature, linked to chemo-resistance in other cancers, can be induced in glioblastoma by microglia. ISG genes and the microglia inducing the ISG expression could be promising novel therapeutic targets in glioblastoma.

The Role of HDAC6 in Glioblastoma Multiforme: A New Avenue to Therapeutic Interventions?

Despite the great advances in basic research results, glioblastoma multiforme (GBM) still remains an incurable tumour. To date, a GBM diagnosis is a death sentence within 15-18 months, due to the high recurrence rate and resistance to conventional radio- and chemotherapy approaches. The effort the scientific community is lavishing on the never-ending battle against GBM is reflected by the huge number of clinical trials launched, about 2003 on 10 September 2024. However, we are still far from both an in-depth comprehension of the biological and molecular processes leading to GBM onset and progression and, importantly, a cure. GBM is provided with high intratumoral heterogeneity, immunosuppressive capacity, and infiltrative ability due to neoangiogenesis. These features impact both tumour aggressiveness and therapeutic vulnerability, which is further limited by the presence in the tumour core of niches of glioblastoma stem cells (GSCs) that are responsible for the relapse of this brain neoplasm. Epigenetic alterations may both drive and develop along GBM progression and also rely on changes in the expression of the genes encoding histone-modifying enzymes, including histone deacetylases (HDACs). Among them, HDAC6-a cytoplasmic HDAC-has recently gained attention because of its role in modulating several biological aspects of GBM, including DNA repair ability, massive growth, radio- and chemoresistance, and de-differentiation through primary cilia disruption. In this review article, the available information related to HDAC6 function in GBM will be presented, with the aim of proposing its inhibition as a valuable therapeutic route for this deadly brain tumour.

Stimuli-Responsive Peptide/siRNA Nanoparticles as a Radiation Sensitizer for Glioblastoma Treatment by Co-Inhibiting RELA/P65 and EGFR

Purpose

To develop a novel approach for increasing radiosensitivity in glioblastoma (GBM) by using targeted nanoparticles to deliver siRNA aimed at silencing the EGFR and RELA/P65 genes, which are implicated in radioresistance.

Patients and Methods

We engineered biodegradable, tumor-targeted, self-assembled, and stimuli-responsive peptide nanoparticles for efficient siRNA delivery. We evaluated the nanoparticles' ability to induce gene silencing and enhance DNA damage under radiation in vitro and in vivo. The nanoparticles were designed to exhibit pH-responsive endosomal escape and αvβ3 integrin targeting, allowing for preferential accumulation at tumor sites and traversal of the blood-brain tumor barrier.

Results

The application of these nanoparticles resulted in significant gene silencing, increased apoptosis, and decreased cell viability. The treatment impaired DNA repair mechanisms, thereby enhancing radiosensitivity in GBM cells. In a GBM mouse model, the combination of nanoparticle treatment with radiotherapy notably prolonged survival without apparent toxicity.

Conclusion

Our findings suggest that nanoparticle-mediated dual gene silencing can effectively overcome GBM radioresistance. This strategy has the potential to improve clinical outcomes in GBM treatment, proposing a promising therapeutic avenue for this challenging malignancy.

Reconstructing the regulatory programs underlying the phenotypic plasticity of neural cancers

Nervous system cancers exhibit diverse transcriptional cell states influenced by normal development, injury response, and growth. However, the understanding of these states' regulation and pharmacological relevance remains limited. Here we present "single-cell regulatory-driven clustering" (scregclust), a method that reconstructs cellular regulatory programs from extensive collections of single-cell RNA sequencing (scRNA-seq) data from both tumors and developing tissues. The algorithm efficiently divides target genes into modules, predicting key transcription factors and kinases with minimal computational time. Applying this method to adult and childhood brain cancers, we identify critical regulators and suggest interventions that could improve temozolomide treatment in glioblastoma. Additionally, our integrative analysis reveals a meta-module regulated by SPI1 and IRF8 linked to an immune-mediated mesenchymal-like state. Finally, scregclust's flexibility is demonstrated across 15 tumor types, uncovering both pan-cancer and specific regulators. The algorithm is provided as an easy-to-use R package that facilitates the exploration of regulatory programs underlying cell plasticity.

ZBTB18 regulates cytokine expression and affects microglia/macrophage recruitment and commitment in glioblastoma

Glioma associated macrophages/microglia (GAMs) play an important role in glioblastoma (GBM) progression, due to their massive recruitment to the tumor site and polarization to a tumor promoting phenotype. GAMs secrete a variety of cytokines, which facilitate tumor cell growth and invasion, and prevent other immune cells from mounting an immune response against the tumor. Here, we demonstrate that zinc finger and BTB containing domain 18 (ZBTB18), a transcriptional repressor with tumor suppressive function in glioblastoma, impairs the production of key cytokines, which function as chemoattractant for GAMs. Consistently, we observe a reduced migration of GAMs when ZBTB18 is expressed by glioblastoma cells, both in cell culture and in vivo experiments. Moreover, RNA sequencing analysis shows that the presence of ZBTB18 in glioblastoma cells alters the commitment of conditioned microglia, suggesting the loss of the immune-suppressive phenotype and the acquisition of pro-inflammatory features. Thus, therapeutic approaches to increase ZBTB18 expression in GBM cells could represent an effective adjuvant to immune therapy in GBM.

Multiomic and clinical analysis of multiply recurrent meningiomas reveals risk factors, underlying biology, and insights into evolution

An important subset of meningiomas behaves aggressively and is characterized by multiple recurrences. We identify clinical, genetic, and epigenetic predictors of multiply recurrent meningiomas (MRMs) and evaluate the evolution of these meningiomas in patient-matched samples. On multivariable binomial logistic regression, MRMs were significantly associated with male sex (P = 0.012), subtotal resection (P = 0.001), higher number of meningiomas on presentation (P = 0.017), and histopathological sheeting (P = 0.002). Multiomic analysis of primary meningiomas revealed that MRMs have greater copy number losses (P = 0.0313) and increased DNA methylation (P = 0.0155). In meningioma cells with knockdown of EDNRB, a locus with greater promoter methylation and decreased gene expression in MRMs had increased proliferation (P < 0.0001). MRM recurrences were found to be similar to primaries but have a greater burden of copy number gains (P < 0.0001) and increased methylation (P = 0.0045). This clinical and multiomic investigation of MRMs harbors implications for the future development of biomarkers and therapeutic agents for these challenging tumors.

HDAC7 drives glioblastoma to a mesenchymal-like state via LGALS3-mediated crosstalk between cancer cells and macrophages

Background: Glioblastoma multiforme (GBM) is an aggressive brain tumour for which current traditional treatment approaches have been unsuccessful, owing to the high genetic heterogeneity and immunosuppressive tumour microenvironment. Methods: Single-cell and spatial transcriptomic data revealed the niche-specific enrichment of mesenchymal-like (MES-like) GBM cells and monocyte-derived macrophages (MDMs); Gain- and loss-of-function assays of HDAC7 was confirmed both in vitro and in vivo assays. Mechanistically, mass spectrum, RNA immunoprecipitation (RIP), and co-immunoprecipitation assays were conducted. Results: We found that HDAC7, which upregulated by TRIM28-mediated sumoylation at the protein levels, inhibited SOX8 expression by mediating H3K27 deacetylation. And the down-regulated SOX8 facilitated the transcriptional activity of JUN, to induce LGALS3 secretion, which then bind to the membrane protein ITGB1 on GSC and MDMs in the autocrine and paracrine manners to facilitate the transformation of the mesenchymal phenotype of GBM and the M2 polarization of MDMs, respectively. In turn, LGALS3 could also secreted by M2 MDMs to promote MES transition of GBM in a paracrine manner, creating a positive feedback loop. In translational medicine, we found that blocking LGALS3 improved the therapeutic sensitivity of HDAC inhibitors. Conclusions: Our findings revealed the role of the novel HDAC7-H3K27ac-SOX8/JUN-LGALS3-ITGB1 axis in maintaining the crosstalk between MES GBM and M2 MDM, highlighting that HDAC7 and LGALS3 may serve as potential prognostic biomarkers and therapeutic targets in GBM.

Pivotal Role of Cranial Irradiation-Induced Peripheral, Intrinsic, and Brain-Engrafting Macrophages in Malignant Glioma

Malignant (high-grade) gliomas are aggressive intrinsic brain tumors that diffusely infiltrate the brain parenchyma. They comprise of World Health Organization (WHO) grade III and IV gliomas. Ionizing radiation or irradiation (IR) is frequently utilized in the treatment of both primary as well as metastatic brain tumors. On the contrary, macrophages (MΦ) are the most copious infiltrating immune cells of all the different cell types colonizing glioma. MΦ at tumor milieu are referred to as tumor-associated macrophages (TAMΦ). In malignant gliomas milieu, TAMΦ are also polarized into two distinct phenotypes such as M1 TAMΦ or M2 TAMΦ, which are capable of inhibiting or promoting tumor growth, respectively. Cranial-IR such as x- and γ-IR are sufficient to induce the migration of peripherally derived MΦ into the brain parenchyma. The IR facilitate a more immunosuppressive milieu via the stimulation of efferocytosis in TAMΦ, and an upsurge of tumor cell engulfment by TAMΦ exhibited detrimental effect of the anti-tumoral immune response in glioma. The MΦ inside the tumor mass are associated with multiple phenomena that include IR resistance and enrichment of the M2 MΦ after IR is able to facilitate glioblastoma multiforme (GBM) recurrence. Reviews on the role of cranial IR-induced peripheral and brain-engrafting macrophages (BeMΦ) in glioma are lacking. Specifically, most studies on peripheral, intrinsic as well as beMΦ on IR focus on WHO grade III and IV. Thus, this review precisely focuses primary on WHO grade III as well as IV gliomas.

Centromeres in cancer: Unraveling the link between chromosomal instability and tumorigenesis

Centromeres are critical structures involved in chromosome segregation, maintaining genomic stability, and facilitating the accurate transmission of genetic information. They are key in coordinating the assembly and help keep the correct structure, location, and function of the kinetochore, a proteinaceous structure vital for ensuring proper chromosome segregation during cell division. Abnormalities in centromere structure can lead to aneuploidy or chromosomal instability, which have been implicated in various diseases, including cancer. Accordingly, abnormalities in centromeres, such as structural rearrangements and dysregulation of centromere-associated proteins, disrupt gene function, leading to uncontrolled cell growth and tumor progression. For instance, altered expression of CENP-A, CENP-E, and others such as BUB1, BUBR1, MAD1, and INCENP, have been shown to ascribe to centromere over-amplification, chromosome missegregation, aneuploidy, and chromosomal instability; this, in turn, can culminate in tumor progression. These centromere abnormalities also promoted tumor heterogeneity by generating genetically diverse cell populations within tumors. Advanced techniques like fluorescence in situ hybridization (FISH) and chromosomal microarray analysis are crucial for detecting centromere abnormalities, enabling accurate cancer classification and tailored treatment strategies. Researchers are exploring strategies to disrupt centromere-associated proteins for targeted cancer therapies. Thus, this review explores centromere abnormalities in cancer, their molecular mechanisms, diagnostic implications, and therapeutic targeting. It aims to advance our understanding of centromeres' role in cancer and develop advanced diagnostic tools and targeted therapies for improved cancer management and treatment.

Elevated α-1,2-mannosidase MAN1C1 in glioma stem cells and its implications for immunological changes and prognosis in glioma patients

Glioblastoma multiforme (GBM) is the most aggressive type of primary brain tumor, and the presence of glioma stem cells (GSCs) has been linked to its resistance to treatments and recurrence. Additionally, aberrant glycosylation has been implicated in the aggressiveness of cancers. However, the influence and underlying mechanism of N-glycosylation on the GSC phenotype and GBM malignancy remain elusive. Here, we performed an in-silico analysis approach on publicly available datasets to examine the function of N-glycosylation-related genes in GSCs and gliomas, accompanied by a qRT-PCR validation experiment. We found that high α-1,2-mannosidase MAN1C1 is associated with immunological functions and worse survival of glioma patients. Differential gene expression analysis and qRT-PCR validation revealed that MAN1C1 is highly expressed in GSCs. Furthermore, higher MAN1C1 expression predicts worse outcomes in glioma patients. Also, MAN1C1 expression is increased in the perinecrotic region of GBM and is associated with immunological and inflammatory functions, a hallmark of the GBM mesenchymal subtype. Further analysis confirmed that MAN1C1 expression is closely associated with infiltrating immune cells and disrupted immune response in the GBM microenvironment. These suggest that MAN1C1 is a potential biomarker for gliomas and may be important as an immunotherapeutic target for GBM.

Patient-derived tumor organoids mimic treatment-induced DNA damage response in glioblastoma

Glioblastoma (GB) is the most common primary malignant brain tumor, characterized by resistance to therapy. Despite aggressive treatment options, GB remains an incurable disease. Invasiveness and heterogeneity are key GB features that cannot be studied in preclinical in vitro models. In this study, we investigated the effects of standard therapy using patient-derived GB organoids (GBOs). GBOs reflect the complexity and heterogeneity of the original tumor tissue. No significant effect on GBO viability or invasion was observed after irradiation and temozolomide treatment. E3 ubiquitin-protein ligase (MDM2), cyclin-dependent kinase inhibitor 1A (CDKN1A), and the serine/threonine kinases ATM and ATR were upregulated at the gene and protein levels after treatment. Our results show that the p53 pathway and DNA-damage response mechanisms were triggered, suggesting that GBOs recapitulate GB therapy resistance. GBOs thus provide a highly efficient platform to assess the specific responses of GB patients to therapy and to further explore therapy resistance.

FACT inhibitor CBL0137, administered in an optimized schedule, potentiates radiation therapy for glioblastoma by suppressing DNA damage repair

Purpose

Standard-of-care for glioblastoma remains surgical debulking followed by temozolomide and radiation. However, many tumors become radio-resistant while radiation damages surrounding brain tissue. Novel therapies are needed to increase the effectiveness of radiation and reduce the required radiation dose. Drug candidate CBL0137 is efficacious against glioblastoma by inhibiting histone chaperone FACT, known to be involved in DNA damage repair. We investigated the combination of CBL0137 and radiation on glioblastoma.

Methods

In vitro, we combined CBL0137 with radiation on U87MG and A1207 glioblastoma cells using the clonogenic assay to evaluate the response to several treatment regimens, and the Fast Halo Assay to examine DNA repair. In vivo, we used the optimum combination treatment regimen to evaluate the response of orthotopic tumors in nude mice.

Results

In vitro, the combination of CBL0137 and radiation is superior to either alone and administering CBL0137 two hours prior to radiation, having the drug present during and for a prolonged period post-radiation, is an optimal schedule. CBL0137 inhibits DNA damage repair following radiation and affects the subcellular distribution of histone chaperone ATRX, a molecule involved in DNA repair. In vivo, one dose of CBL0137 is efficacious and the combination of CBL0137 with radiation increases median survival over either monotherapy.

Conclusions

CBL0137 is most effective with radiation for glioblastoma when present at the time of radiation, immediately after and for a prolonged period post-radiation, by inhibiting DNA repair caused by radiation. The combination leads to increased survival making it attractive as a dual therapy.

Glioblastoma mesenchymal subtype enhances antioxidant defence to reduce susceptibility to ferroptosis

Glioblastoma (GBM) represents an aggressive brain tumor, characterized by intra- and inter-tumoral heterogeneity and therapy resistance, leading to unfavourable prognosis. An increasing number of studies pays attention on the regulation of ferroptosis, an iron-dependent cell death, as a strategy to reverse drug resistance in cancer. However, the debate on whether this strategy may have important implications for the treatment of GBM is still ongoing. In the present study, we used ferric ammonium citrate and erastin to evaluate ferroptosis induction effects on two human GBM cell lines, U-251 MG, with proneural characteristics, and T98-G, with a mesenchymal profile. The response to ferroptosis induction was markedly different between cell lines, indeed T98-G cells showed an enhanced antioxidant defence, with increased glutathione levels, as compared to U-251 MG cells. Moreover, using bioinformatic approaches and analysing publicly available datasets from patients' biopsies, we found that GBM with a mesenchymal phenotype showed an up-regulation of several genes involved in antioxidant mechanisms as compared to proneural subtype. Thus, our results suggest that GBM subtypes differently respond to ferroptosis induction, emphasizing the significance of further molecular studies on GBM to better discriminate between various tumor subtypes and progressively move towards personalized therapy.

Multi-omics Analysis Revealed that the CCN Family Regulates Cell Crosstalk, Extracellular Matrix, and Immune Escape, Leading to a Poor Prognosis of Glioma

The CCN family is a group of matricellular proteins associated with the extracellular matrix. This study aims to explore the role of the CCN family in glioma development and its implications in the tumor microenvironment. Through analysis of bulk RNA-seq cohorts, correlations between CCN family expression and glioma subtypes, patient survival, and bioactive pathway enrichment were investigated. Additionally, single-cell datasets were employed to identify novel cell subgroups, followed by analyses of cell communication and transcription factors. Spatial transcriptomic analysis was utilized to validate the CCN family's involvement in glioma. Results indicate overexpression of CYR61,CTGF, and WISP1 in glioma, associated with unfavorable subtypes and reduced survival. Enrichment analyses revealed associations with oncogenic pathways, while CTGF and WISP1 expression correlated with increased infiltration of regulatory T cells and M2 macrophages. Single-cell analysis identified MES-like cells as the highest CCN expression. Moreover, intercellular signal transduction analysis demonstrated active pathways, including SPP1-CD44, in cell subgroups with elevated CYR61 and CTGF expression. Spatial transcriptomic analysis confirmed co-localization of CYR61,CTGF and SPP1-CD44 with high oncogenic pathway activity. These findings suggest that CCN family members may serve as potential prognostic biomarkers and therapeutic targets for glioma.

Oncogenic roles of long non-coding RNAs in essential glioblastoma signaling pathways

Glioblastoma multiforme (GBM) is an aggressive and diffuse type of glioma with the lowest survival rate in patients. The recent failure of multiple treatments suggests that targeting several targets at once may be a different strategy to overcome GBM carcinogenesis. Normal function of oncogenes and tumor suppressor genes need for the preservation of regular cellular processes, so any defects in these genes' activity, operate the corresponding signaling pathways, which initiate carcinogenic processes. Long non-coding RNAs (lncRNAs) that can be found in the cytoplasm or nucleus of the cells, control the transcription and translation of genes. LncRNAs perform a variety of functions, including epigenetic alteration, protein modification and stability, transcriptional regulation, and competition for miRNA that regulate mRNA translation through sponging miRNAs. Identification of various oncogenic lncRNAs and their multiple roles in brain cancers making them potential candidates for use as glioma diagnostic, prognostic, and therapeutic targets in the future. This study highlighted multiple oncogenic lncRNAs and classified them into different signaling pathways based on the regulated target genes in glioblastoma.

ST3GAL1 Promotes Malignant Phenotypes in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) has a poor prognosis, and elucidation of the molecular mechanisms underlying iCCA malignancy is of great significance. Glycosylation, an important post-translational modification, is closely associated with tumor progression. Altered glycosylation, including aberrant sialylation resulting from abnormal expression of sialyltransferases (STs) and neuraminidases (NEUs), is a significant feature of cancer cells. However, there is limited information on the roles of STs and NEUs in iCCA malignancy. Here, utilizing our proteogenomic resources from a cohort of 262 patients with iCCA, we identified ST3GAL1 as a prognostically relevant molecule in iCCA. Moreover, overexpression of ST3GAL1 promoted proliferation, migration, and invasion and inhibited apoptosis of iCCA cells in vitro. Through proteomic analyses, we identified the downstream pathway potentially regulated by ST3GAL1, which was the NF-κB signaling pathway, and further demonstrated that this pathway was positively correlated with malignancy in iCCA cells. Notably, glycoproteomics showed that O-glycosylation was changed in iCCA cells with high ST3GAL1 expression. Importantly, the altered O-glycopeptides underscored the potential utility of O-glycosylation profiling as a discriminatory marker for iCCA cells with ST3GAL1 overexpression. Additionally, miR-320b was identified as a post-transcriptional regulator of ST3GAL1, capable of suppressing ST3GAL1 expression and then reducing the proliferation, migration, and invasion abilities of iCCA cell lines. Taken together, these results suggest ST3GAL1 could serve as a promising therapeutic target for iCCA.