Guerrero-Cazares, Hugo

Cancer stem cells (CSCs) are increasingly recognized as central drivers of tumorigenesis, therapeutic resistance, and recurrence across diverse malignancies. This review synthesizes our current understanding of CSC biology across CNS tumors, with a focus on glioblastoma, where stem-like cells are sustained by specialized and overlapping tumor microenvironmental niches. Perivascular, hypoxic, invasive, immunosuppressive, and extracellular matrix-associated niches cooperatively enforce stemness, metabolic adaptability, immune evasion, and phenotypic plasticity, enabling CSC persistence despite maximal surgical resection and standard-of-care therapy. Notably, CSCs extend beyond radiographically defined tumor margins and populate peritumoral regions, providing a biological basis for near-universal recurrence. Advances in multiparametric imaging, stem cell-based ex vivo and in vivo models, and single-cell and spatial profiling have refined insight into CSC heterogeneity, niche dependence, and treatment resistance. Together, these findings reframe therapeutic strategies, highlighting the need for function-preserving maximal resection and multimodal therapies that target both CSC-intrinsic pathways and their supportive microenvironments.

ABSTRACT Glioblastoma (GBM), the most aggressive primary brain tumour in adults, presents significant challenges due to its universal recurrence and limited survival rates. A key driver of GBM progression is the subpopulation of brain tumour‐initiating cells (BTICs), which contribute to therapy resistance and interact with the tumour microenvironment, particularly the cellular components in the subventricular zone (SVZ). Extracellular vesicles (EVs) are critical mediators of intercellular communication, carrying bioactive molecules, such as proteins and RNAs, that can modulate the behaviour of recipient cells. This study investigates the role of EVs in GBM's communication with non‐cancer cells. We utilised the proximity‐labelling system TurboID to achieve global and unbiased labelling of proteins within GBM‐derived EVs. By inducing TurboID expression in primary‐cultured human BTICs from GBM patients, we achieved efficient biotinylation of EV proteins without compromising vesicle integrity, and performed proteomic analysis of biotinylated proteins, which revealed a diverse cargo within BTIC‐EVs. Our method marks the first implementation of TurboID for unbiased global labelling of EV protein cargo in primary cells. This approach facilitates the investigation of EV‐mediated communication and potential therapeutic targets, contributing to the understanding of GBM's complex interactions with the brain's microenvironment and identification of biomarkers for improved diagnosis and treatment response.

Glioblastoma (GBM) is the most frequent and aggressive malignant primary tumor of the central nervous system in adults, with an incidence of 3.23 per 100,000 people. Despite the existence of various therapeutic approaches, the absence of a cure and the unfavorable prognosis persist for this neoplasm, with a median survival of approximately 8-15 months and a 5-year survival rate of 6.9%. In this review, we address the epidemiology, histopathology, molecular characteristics, and treatment of GBM. We highlight the relationship of GBM with the microenvironment in the lateral ventricle wall and the cerebrospinal fluid. The location of GBM in this region results in more aggressive tumors and shorter life expectancy for patients. Understanding the malignancy mechanisms that hinder remission, treatment, and positive prognosis opens the possibility of improving diagnostic and therapeutic interventions against GBM.

Glioblastoma (GBM) is the most prevalent and aggressive malignant primary brain tumor. GBM proximal to the lateral ventricles (LVs) is more aggressive, potentially because of subventricular zone contact. Despite this, cross-talk between GBM and neural stem/progenitor cells (NSC/NPCs) is not well understood. Using cell-specific proteomics, we show that LV-proximal GBM prevents neuronal maturation of NSCs through induction of senescence. In addition, GBM brain tumor–initiating cells (BTICs) increase expression of cathepsin B (CTSB) upon interaction with NPCs. Lentiviral knockdown and recombinant protein experiments reveal that both cell-intrinsic and soluble CTSB promote malignancy-associated phenotypes in BTICs. Soluble CTSB stalls neuronal maturation in NPCs while promoting senescence, providing a link between LV-tumor proximity and neurogenesis disruption. Last, we show LV-proximal CTSB up-regulation in patients, showing the relevance of this cross-talk in human GBM biology. These results demonstrate the value of proteomic analysis in tumor microenvironment research and provide direction for new therapeutic strategies in GBM.

Abstract Background Mesenchymal stromal cells (MSCs) have a dynamic secretome that plays a critical role in tissue repair and regeneration. However, studying the MSC secretome in mixed-culture disease models remains challenging. This study aimed to develop a mutant methionyl-tRNA synthetase-based toolkit (MetRSL274G) to selectively profile secreted proteins from MSCs in mixed-culture systems and demonstrate its potential for investigating MSC responses to pathological stimulation.Methods We used CRISPR/Cas9 homology-directed repair to stably integrate MetRSL274G into cells, enabling the incorporation of the non-canonical amino acid, azidonorleucine (ANL), and facilitating selective protein isolation using click chemistry. MetRSL274G was integrated into both in H4 cells and induced pluripotent stem cells (iPSCs) for a series of proof-of-concept studies. Following iPSC differentiation into induced-MSCs, we validated their identity and co-cultured MetRSL274G-expressing iMSCs with naïve or lipopolysaccharide- (LPS) treated THP-1 cells. We then profiled the iMSC secretome using antibody arrays.Results Our results showed successful integration of MetRSL274G into targeted cells, allowing specific isolation of proteins from mixed-culture environments. We also demonstrated that the secretome of MetRSL274G-expressing iMSCs can be differentiated from that of THP-1 cells in co-culture, and is altered when co-cultured with LPS-treated THP-1 cells compared to naïve THP-1 cells.Conclusions The MetRSL274G-based toolkit we have generated enables selective profiling of the MSC secretome in mixed-culture disease models. This approach has broad applications for examining not only MSC responses to models of pathological conditions, but any other cell type that can be differentiated from iPSCs. This can potentially reveal novel MSC-mediated repair mechanisms and advancing our understanding of tissue regeneration processes.

Glioblastoma (GBM) remains the most common and aggressive malignant primary brain tumor [...]

OBJECTIVE The vertebral column is the most common site for skeletal metastasis, often leading to debilitating pain and weakness. Metastatic cancer has unique genetic drivers that potentiate tumorigenicity. There is an unmet need for novel targeted therapy in patients with spinal metastatic disease. METHODS The authors assessed the effect of verteporfin-induced yes-associated protein (YAP) inhibition on spine metastatic cell tumorigenicity and radiation sensitivity in vitro. Animal studies used a subcutaneous xenograft mouse model to assess the use of systemic intraperitoneal verteporfin (IP-VP) and intratumoral verteporfin microparticles (IT-VP) to inhibit the tumorigenicity of lung and breast spinal metastatic tumors from primary patient-derived tissue. RESULTS Verteporfin led to a dose-dependent decrease in migration, clonogenicity, and cell viability via inhibition of YAP and downstream effectors cyclin D1, CTGF, TOP2A, ANDRD1, MCL-1, FOSL2, KIF14, and KIF23. This was confirmed with knockdown of YAP. Verteporfin has an additive response when combined with radiation, and knockdown of YAP rendered cells more sensitive to radiation. The addition of verteporfin to YAP knockdown cells did not significantly alter migration, clonogenicity, or cell viability. IP-VP and IT-VP led to diminished tumor growth (p < 0.0001), especially when combined with radiation (p < 0.0001). Tissue analysis revealed diminished expression of YAP (p < 0.0001), MCL-1 (p < 0.0001), and Ki-67 (p < 0.0001) in tissue from verteporfin-treated tumors compared with vehicle-treated tumors. CONCLUSIONS This is the first study to demonstrate that verteporfin-mediated inhibition of YAP leads to diminished tumorigenicity in lung and breast spinal metastatic cancer cells. Targeting of YAP with verteporfin offers promising results that could be translated to human clinical trials.

Metabolic rewiring in glioblastoma (GBM) is linked to intra- and extracellular pH regulation. In this study, we sought to characterize the role of melatonin on intracellular pH modulation and metabolic consequences to identify the mechanisms of action underlying melatonin oncostatic effects on GBM tumor initiating cells. GBM tumor initiating cells were treated at different times with melatonin (1.5 and 3.0 mM). We analyzed melatonin’s functional effects on GBM proliferation, cell cycle, viability, stemness, and chemo-radiosensitivity. We then assessed the effects of melatonin on GBM metabolism by analyzing the mitochondrial and glycolytic parameters. We also measured the intracellular and extracellular pH. Finally, we tested the effects of melatonin on a mouse subcutaneous xenograft model. We found that melatonin downregulated LDHA and MCT4, decreasing lactate production and inducing a decrease in intracellular pH that was associated with an increase in ROS and ATP depletion. These changes blocked cell cycle progression and induced cellular death and we observed similar results in vivo. Melatonin’s cytotoxic effects on GBM were due, at least in part, to intracellular pH modulation, which has emerged as a newly identified mechanism, providing new insights into the oncostatic effect of melatonin on GBM.

AbstractMicroglia have fundamental roles in health and disease; however, effects of age, sex, and genetic factors on human microglia have not been fully explored. We applied bulk and single‐cell approaches to comprehensively characterize human microglia transcriptomes and their associations with age, sex, and APOE. We identified a novel microglial signature, characterized its expression in bulk tissue and single‐cell microglia transcriptomes. We discovered microglial co‐expression network modules associated with age, sex, and APOE‐ε4 that are enriched for lipid and carbohydrate metabolism genes. Integrated analyses of modules with single‐cell transcriptomes revealed significant overlap between age‐associated module genes and both pro‐inflammatory and disease‐associated microglial clusters. These modules and clusters harbor known neurodegenerative disease genes including APOE, PLCG2, and BIN1. Meta‐analyses with published bulk and single‐cell microglial datasets further supported our findings. Thus, these data represent a well‐characterized human microglial transcriptome resource and highlight age, sex, and APOE‐related microglial immunometabolism perturbations with potential relevance in neurodegeneration.