Search Results (128)

Glioblastoma (GBM) is a highly aggressive brain tumor marked by invasive growth and therapy resistance. Tumor cells adapt to hostile conditions, such as hypoxia and nutrient deprivation, by activating survival mechanisms including autophagy and metabolic reprogramming. Among GBM-associated changes, hypersialylation, particularly, the aberrant expression of polysialic acid (PSA), has been linked to increased plasticity, motility, and immune evasion. PSA, a long α2,8-linked sialic acid polymer typically attached to the NCAM, is abundant in the embryonic brain and re-expressed in cancers, correlating with poor prognosis. Here, we investigated how PSA expression was regulated in GBM cells under nutrient-limiting conditions. Serum starvation induced a marked increase in PSA-NCAM, driven by upregulation of the polysialyltransferase ST8SiaIV and an autophagy-dependent recycling of sialic acids from degraded glycoproteins. Inhibition of autophagy or sialidases impaired PSA induction, and PSA regulation appeared dependent on p53 function. Immunohistochemical analysis of GBM tissues revealed co-localization of PSA and LC3, particularly around necrotic regions. In conclusion, we identified a novel mechanism by which GBM cells sustain PSA-NCAM expression via autophagy-mediated sialic acid recycling under nutrient stress. This pathway may enhance cell migration, immune escape, and stem-like properties, offering a potential therapeutic target in GBM. Full article

Glioblastoma (GBM) is a highly aggressive and heterogeneous brain tumor. Glioma stem-like cells (GSCs) play a central role in tumor progression, therapeutic resistance, and recurrence. Although immune cells are known to shape the GBM microenvironment, the impact of antigen-presenting-cell (APC) signature genes on tumor-intrinsic phenotypes remains underexplored. We analyzed both bulk- and single-cell RNA sequencing datasets of GBM to investigate the association between APC gene expression and tumor-cell states, including stemness and metabolic reprogramming. Signature scores were computed using curated gene sets related to APC activity, KEGG metabolic pathways, and cancer hallmark pathways. Protein–protein interaction (PPI) networks were constructed to examine the links between immune regulators and metabolic programs. The high expression of APC-related genes, such as HLA-DRA, CD74, CD80, CD86, and CIITA, was associated with lower stemness signatures and enhanced inflammatory signaling. These APC-high states (mean difference = –0.43, adjusted p < 0.001) also showed a shift in metabolic activity, with decreased oxidative phosphorylation and increased lipid and steroid metabolism. This pattern suggests coordinated changes in immune activity and metabolic status. Furthermore, TNF-α and other inflammatory markers were more highly expressed in the less stem-like tumor cells, indicating a possible role of inflammation in promoting differentiation. Our findings revealed that elevated APC gene signatures are associated with more differentiated and metabolically specialized GBM cell states. These transcriptional features may also reflect greater immunogenicity and inflammation sensitivity. The APC metabolic signature may serve as a useful biomarker to identify GBM subpopulations with reduced stemness and increased immune engagement, offering potential therapeutic implications. Full article

The WHO estimates that nearly 10–15% of cancers have a known viral etiology, although this number is likely an underestimate. In glioblastoma (GBM), the most common primary brain malignancy, viral associations have been proposed and investigated without a definitive etiology. Viral–host interactions are known to alter cellular growth and stem cell programming, as well as modulate innate immune signaling. However, in GBM, the multifaceted role of endogenous or exogenous viral expression remains unclear. Here, we provide a review of common viral associations in GBM and discuss how these viruses modulate intrinsic cellular processes to enhance anti-viral immune response or suppress anti-tumor immunity. Full article

Glioblastoma (GBM) is the most aggressive and challenging brain cancer, in terms of diagnosis and therapy. The highly infiltrative glioblastoma stem cells (GSCs) are difficult to visualize and surgically remove with the current diagnostic tools, which often lead to misdiagnosis and false-positive results. In this study, we focused on a groundbreaking tool for specifically visualizing and removing GSCs. We exploited the specific binding of A40s aptamer to EphA2 for the selective delivery of Near-Infrared Dyes (NIR-Dyes), like IR700DX and ICG, both in vitro and in vivo. The A40s aptamer, engineered through the NIR-Dye conjugation, did not affect aptamer binding ability; indeed, A40s-NIR-Dye conjugates bound GLI261 stem-like cells and patient-derived GSCs in vitro; moreover, they induced cell death upon photodynamic therapy treatment (PDT). Additionally, when systemically administrated, the A40s-NIR-Dye conjugates allowed GSC visualization and accumulated in tumor mass. This allows GSCs detection and treatment. Our findings demonstrate the potential use of A40s aptamer as a targeted therapeutic approach and imaging tool in vivo for GSCs, paving the way for improved, more effective, and less invasive GBM management. Full article

Background: Glioblastoma (GBM) is the most malignant brain tumor, with a cellular hierarchy dominated by glioma stem cells (GSCs). Understanding global communications among GSCs and other cells helps us identify potential new therapeutic targets. In this study, multi-transcriptomic analysis was utilized to explore the communication pattern of GSCs in GBM. Methods: CellChat was used to quantitatively infer and analyze intercellular communication networks from GBM single-cell RNA-sequencing (scRNA-seq) data. Gene set enrichment analysis (GSEA) was conducted to identify specific biological pathways (epithelial–mesenchymal transition, EMT) involved in the communication pattern of GSCs. Spatial transcriptomic database was used to support the relationship between EMT and GSC proliferation. Single-sample GSEA (ssGSEA) was employed to assess which GSC state exhibited the strongest association with the EMT signature. Results: The cell communication pattern of GSCs is mostly related to EMT. Multiple EMT-related genes are highly expressed in GBM, particularly in GSCs, which are associated with poor prognosis. In addition, EMT-related genes are most enriched in mesenchymal-like (MES-like) GSCs. Tumor patients with MES-like GSC-enriched signatures demonstrate the most unfavorable prognosis compared to those harboring proneural-like (PN-like) or classical-like (CL-like) GSCs. Conclusions: This study suggests that GSCs facilitate GBM progression through intercellular communication in the pattern of EMT. EMT-associated genes may drive the differentiation of GSCs toward a MES-like phenotype, thereby leading to poorer clinical outcomes. Consequently, targeting EMT-related pathways could represent a novel therapeutic strategy for GBM treatment. Full article

Background: Glioblastoma (GBM) remains almost uniformly fatal, owing in part to therapy-resistant cancer stem-like cells (CSCs) and to temozolomide (TMZ) resistance driven by O⁶-methylguanine-DNA methyltransferase (MGMT). Differentiation therapy with all-trans retinoic acid (ATRA) has the potential to attenuate stemness and sensitize GBM to TMZ. We therefore asked whether ATRA reduces expression of key CSC markers and MGMT in established GBM lines. Methods: Two established human GBM cell lines, U87-MG and A172, were cultured under neurosphere-promoting conditions to enrich for potential stem-like subpopulations. Cells were treated with either 1 µM ATRA or vehicle control (DMSO) for 5 days. Total RNA was extracted, and cDNA was synthesized. Quantitative Real-Time PCR (qPCR) assessed relative mRNA expression levels of key stemness transcription factors (SOX2, NES) and the DNA repair gene MGMT and corresponding protein levels were measured by an Enzyme-Linked Immunosorbent Assay (ELISA). Gene expression was normalized to the geometric mean of two validated housekeeping genes (GAPDH, ACTB). Relative quantification was calculated using the ΔΔCt method, and statistical significance was determined using Student’s t-tests. Results: ATRA markedly suppressed stemness and MGMT in both lines. In U87-MG, SOX2 mRNA fell 3.7-fold (p = 0.0008) and protein 2.99-fold (148.3 ± 6.0 → 49.7 ± 2.7 pg µg⁻¹; p = 0.0002); Nestin dropped 4.1-fold (p = 0.0005) and 3.51-fold (450.0 ± 17.3 → 128.3 ± 4.4 pg µg⁻¹; p = 0.00008). MGMT decreased 2.6-fold at transcript level (p = 0.0065) and 2.11-fold at protein level (81.7 ± 4.4 → 38.7 ± 1.8 pg µg⁻¹; p = 0.0005). In A172, SOX2 was reduced 2.9-fold (p = 0.0041) and 2.31-fold (p = 0.0007); Nestin 3.3-fold (p = 0.0028) and 2.79-fold (p = 0.00009). MGMT declined 2.2-fold (p = 0.0132) and 1.82-fold (p = 0.0015), respectively. Conclusions: Five-day exposure to ATRA diminishes SOX2, Nestin, and MGMT at both mRNA and protein levels in stem-enriched GBM cultures, supporting the premise that ATRA-induced differentiation can concurrently blunt CSC traits and TMZ-resistance mechanisms. These data provide a molecular rationale for testing ATRA in combination regimens aimed at improving GBM therapy. Full article

Attempts to activate an anti-tumor immune response in glioblastoma (GBM) have been met with many challenges due to its inherently immunosuppressive tumor microenvironment. The degree and mechanisms by which molecularly and phenotypically diverse tumor-propagating glioma stem cells (GSCs) contribute to this state are poorly defined. In this study, our multifaceted approach combining bioinformatics analyses of clinical and experimental datasets, single-cell sequencing, and the molecular and pharmacologic manipulation of patient-derived cells identified GSCs expressing immunosuppressive effectors mimicking regulatory T cells (Tregs). We showed that this immunosuppressive Treg-like (ITL) GSC state is specific to the mesenchymal GSC subset and is associated with and driven specifically by TGFβ type II receptor (TGFBR2) in contrast to TGFBR1. Transgenic TGFBR2 expression in patient-derived GBM neurospheres promoted a mesenchymal transition and induced a six-gene ITL signature consisting of CD274 (PD-L1), NT5E (CD73), ENTPD1 (CD39), LGALS1 (galectin-1), PDCD1LG2 (PD-L2), and TGFB1. This TGFBR2-driven ITL signature was identified in clinical GBM specimens, patient-derived GSCs, and systemic mesenchymal malignancies. TGFBR2^high GSCs inhibited CD4+ and CD8+ T cell viability and their capacity to kill GBM cells, effects reversed by pharmacologic and shRNA-based TGFBR2 inhibition. Collectively, our data identify an immunosuppressive GSC state that is TGFBR2-dependent and susceptible to TGFBR2-targeted therapeutics. Full article

Glioblastoma (GBM) is an exceedingly aggressive primary brain tumor defined by rapid growth, extensive infiltration, and resistance to standard therapies. A central factor driving these malignancies is the subpopulation of glioblastoma stem cells (GSCs), which possess self-renewal capacity, multipotency, and the ability to regenerate tumor heterogeneity. GSCs contribute to key hallmarks of GBM pathobiology, including relentless progression, resistance to chemotherapy and radiotherapy, and inevitable recurrence. GSCs exhibit distinct molecular signatures, enhanced DNA repair, and metabolic adaptations that protect them against conventional treatments. Moreover, they reside within specialized niches—such as perivascular or hypoxic microenvironments—that sustain stemness, promote immunosuppression, and facilitate angiogenesis. Recent discoveries highlight signaling pathways like Notch, Wnt/β-catenin, Hedgehog, STAT3-PARN, and factors such as TFPI2 and HML-2 as critical regulators of GSC maintenance, plasticity, and immune evasion. These findings underscore the complexity of GSC biology and their pivotal role in driving GBM heterogeneity and therapeutic failure. Emerging therapeutic strategies aim to target GSCs through multiple avenues, including surface markers, immunotherapeutics (e.g., CAR T cells), metabolic vulnerabilities, and combination regimens. Advances in patient-derived organoids, single-cell omics, and 3D co-culture models enable more accurate representation of the tumor ecosystem and personalized therapeutic approaches. Ultimately, improved understanding of GSC-specific targets and the tumor microenvironment promises more effective interventions, paving the way toward better clinical outcomes for GBM patients. Full article

InfoScan is a novel bioinformatics tool designed for the comprehensive analysis of full-length single-cell RNA sequencing (scRNA-seq) data. It enables the identification of unannotated transcripts and rare cell populations, providing a powerful platform for transcriptome characterization. In this study, InfoScan was applied to glioblastoma multiforme (GBM), identifying a rare “neoplastic-stemness” subpopulation exhibiting cancer stem cell-like features. Functional analyses suggested that tumor-associated macrophages (TAMs) secrete SPP1, which binds to CD44 on neoplastic-stemness cells, activating the PI3K/AKT pathway and driving lncRNA transcription to promote metastasis. Integration of TCGA and CGGA datasets further supported these findings, highlighting key mutations associated with the neoplastic-stemness subpopulation. Drug sensitivity assays indicated that neoplastic-stemness cells might be sensitive to omipalisib, a PI3K inhibitor, pointing to a potential therapeutic target. InfoScan offers a robust framework for exploring complex transcriptomic landscapes and characterizing rare cell populations, providing valuable insights into GBM biology and advancing precision cancer therapy. Full article

Background/Objectives: Late epilepsy occurring in the late stage after glioblastoma (GBM) resection is suggested to be caused by increased extracellular glutamate (Glu). To elucidate the mechanism underlying postoperative late epilepsy, the present study aimed to investigate the expressions and relations of molecules related to Glu metabolism in tumor tissues from GBM patients and cultured glioma stem-like cells (GSCs). Methods: Expressions of CD44, xCT and excitatory amino acid transporter (EAAT) 2 and extracellular Glu concentration in GBM patients with and without epilepsy were examined and their relationships were analyzed. For the study using GSCs, expressions and relationships of the same molecules were analyzed and the effects of CD44 knock-down on xCT, EAAT2, and Glu were investigated. In addition, the effects of hypoxia on the expressions of these molecules were investigated. Results: Tumor tissues highly expressed CD44 and xCT in the periphery of GBM with epilepsy, whereas no significant difference in EAAT2 expression was seen between groups with and without epilepsy. Extracellular Glu concentration was higher in patients with epilepsy than those without epilepsy. GSCs displayed reciprocal expressions of CD44 and xCT. Concentrations of extracellular Glu coincided with the degree of xCT expression, and CD44 knock-down elevated xCT expression and extracellular Glu concentrations. Hypoxia of 1% O₂ elevated expression of CD44, while 5% O₂ increased xCT and extracellular Glu concentration. Conclusions: Late epilepsy after GBM resection was related to extracellular Glu concentrations that were regulated by reciprocal expression of CD44 and xCT, which were stimulated by differential hypoxia for each molecule. Full article

Background/Objectives: Glioblastoma (GBM), a highly aggressive grade IV astrocytoma, poses a major therapeutic challenge due to the resistance of cancer stem cells (CSCs) existing within its cell population to the conventional therapies. Recently, we reported that RNA interference targeting CSC protection mechanism significantly improved therapeutic efficacy. However, challenges remain, including limited transfection efficiency in neural cells and the difficulty of crossing the blood–brain barrier (BBB). Methods: In this study, we investigated the potential of exosome-mediated delivery of therapeutic cargo to GBM cells by engineering the exosomes to carry green fluorescent protein (GFP) and expressing brain-homing peptide (BHP) on their surface, which has high affinity to the neural cells. Results: We found that BHP-modified exosomes doubled GFP delivery efficacy from 20% to 40%, outperforming traditional transfection methods like lipofection in vitro. In vivo, BHP-modified exosomes demonstrated an ability to cross the BBB and targeted cargo delivery to brain regions following intranasal and subcutaneous administration. Conclusions: These results underscore the potential of engineered exosomes for efficient cargo delivery to enhance therapeutic efficacy against brain tumors and suggest novel avenues for delivering biomolecules to the brain in the treatment of neurological disorders. Full article

Glioblastoma (GBM) is the most common and lethal intracranial tumor in adults. Despite advances in the understanding of the molecular events responsible for disease development and progression, survival rates and mortality statistics for GBM patients have been virtually unchanged for decades and chemotherapeutic drugs used to treat GBM are limited. Arsenic derivatives, known as highly effective anticancer agents for leukemia therapy, has been demonstrated to exhibit cytocidal effects toward GBM cells by inducing cell death, cell cycle arrest, inhibition of migration/invasion, and angiogenesis. Differentiation induction of glioma stem-like cells (GSCs) and inhibition of neurosphere formation have also been attributed to the cytotoxicity of arsenic derivatives. Intriguingly, similar cytotoxic effects against GBM cells and GSCs have also been observed in natural agents such as anthocyanidins, tetrandrine, and bufadienolides. In the current review, we highlight the available data on the molecular mechanisms underlying the multifaceted anticancer activity of arsenic compounds and natural agents against cancer cells, especially focusing on GBM cells and GCSs. We also outline possible strategies for developing anticancer therapy by combining natural agents and arsenic compounds, as well as temozolomide, an alkylating agent used to treat GBM, in terms of improvement of chemotherapy sensitivity and minimization of side effects. Full article

The gold standard assay for radiation response is the clonogenic assay, a normalized colony formation assay (CFA) that can capture a broad range of radiation-induced cell death mechanisms. Traditionally, this assay relies on two-dimensional (2D) cell culture conditions with colonies counted by fixing and staining protocols. While some groups have converted these to three-dimensional (3D) conditions, these models still utilize 2D-like media compositions containing serum that are incompatible with stem-like cell models such as brain tumor initiating cells (BTICs) that form self-aggregating spheroids in neural stem cell media. BTICs are the preferred patient-derived model system for studying glioblastoma (GBM) as they tend to better retain molecular and phenotypic characteristics of the original tumor tissue. As such, it is important that preclinical radiation studies should be adapted to BTIC conditions. In this study, we describe a series of experimental approaches for performing CFA experiments with BTIC cultures. Our results indicate that serum-free clonogenic assays are feasible for combination drug and radiation testing and may better facilitate translatability of preclinical findings. Full article

Background: Targeted therapies have been largely ineffective against glioblastoma (GBM) owing to the tumor’s heterogeneity and intrinsic and adaptive treatment resistance. Targeting multiple pro-survival pathways simultaneously may overcome these limitations and yield effective treatments. Heat shock protein 90 (HSP90), an essential component of the epichaperome complex, is critical for the proper folding and activation of several pro-survival oncogenic proteins that drive GBM biology. Methods: Using a panel of biochemical and biological assays, we assessed the expression of HSP90 and its downstream targets and the effects of PU-H71, a highly specific and potent HSP90 inhibitor, on target modulation, downstream biochemical alterations, cell cycle progression, proliferation, migration, and apoptosis in patient-derived glioma stem-like cells (GSCs) with molecular profiles characteristic of GBM, as well as commercial glioma cell lines and normal human astrocytes (NHAs). Results: HSP90 inhibition by PU-H71 in GSCs significantly reduced cell proliferation, colony formation, wound healing, migration, and angiogenesis. In glioma cells, but not NHAs, potent PU-H71-mediated HSP90 inhibition resulted in the downregulation of pro-survival client proteins such as EGFR, MAPK, AKT, and S6. This reduction in pro-survival signals increased glioma cells’ sensitivity to temozolomide, a monofunctional alkylator, and the combination of PU-H71 and temozolomide had greater anticancer efficacy than either agent alone. Conclusions: These results confirm that HSP90 is a strong pro-survival factor in molecularly heterogeneous gliomas and suggest that epichaperome inhibition with HSP90 inhibitors warrants further investigation for the treatment of gliomas. Full article

Glioblastoma multiforme (GBM) is among the most aggressive brain cancers, and it contains glioma stem cells (GSCs) that drive tumor initiation, progression, and recurrence. These cells resist conventional therapies, contributing to high recurrence rates in GBM patients. Developing in vitro models that mimic the tumor microenvironment (TME), particularly the GSC niche, is crucial for understanding GBM growth and therapeutic resistance. Three-dimensional (3D) spheroid models provide a more physiologically relevant approach than traditional two-dimensional (2D) cultures, recapitulating key tumor features like hypoxia, cell heterogeneity, and drug resistance. This review examines scaffold-free and scaffold-based methods for generating 3D GBM spheroids, focusing on their applications in studying the cancer stem cell niche. The discussion encompasses methods such as the hanging drop, low-adhesion plates, and magnetic levitation, alongside advancements in embedding spheroids within extracellular matrix-based hydrogels and employing 3D bioprinting to fabricate more intricate tumor models. These 3D culture systems offer substantial potential for enhancing our understanding of GBM biology and devising more effective targeted therapies. Full article