Caveolin-1, a Key Mediator Across Multiple Pathways in Glioblastoma and an Independent Negative Biomarker of Patient Survival

Caveolae: Metabolic Platforms at the Crossroads of Health and Disease

Caveolae are small flask-shaped invaginations of the plasma membrane enriched in cholesterol and sphingolipids. They play a critical role in various cellular processes, including signal transduction, endocytosis, and mechanotransduction. Caveolin proteins, specifically Cav-1, Cav-2, and Cav-3, in addition to their role as structural components of caveolae, have been found to regulate the activity of signaling molecules. A growing body of research has highlighted the pivotal role of caveolae and caveolins in maintaining cellular metabolic homeostasis. Indeed, studies have demonstrated that caveolins interact with the key components of insulin signaling, glucose uptake, and lipid metabolism, thereby influencing energy production and storage. The dysfunction of caveolae or the altered expression of caveolins has been associated with metabolic disorders, including obesity, type 2 diabetes, and ocular diseases. Remarkably, mutations in caveolin genes can disrupt cellular energy balance, promote oxidative stress, and exacerbate metabolic dysregulation. This review examines current research on the molecular mechanisms through which caveolae and caveolins regulate cellular metabolism, explores their involvement in the pathogenesis of metabolic disorders, and discusses potential therapeutic strategies targeting caveolin function and the stabilization of caveolae to restore metabolic homeostasis.

Unite and Conquer: Association of Two G-Quadruplex Aptamers Provides Antiproliferative and Antimigration Activity for Cells from High-Grade Glioma Patients

Background: High-grade gliomas remain a virtually incurable form of brain cancer. Current therapies are unable to completely eradicate the tumor, and the tumor cells that survive chemotherapy or radiation therapy often become more aggressive and resistant to further treatment, leading to inevitable relapses. While the antiproliferative effects of new therapeutic molecules are typically the primary focus of research, less attention is given to their influence on tumor cell migratory activity, which can play a significant role in recurrence. A potential solution may lie in the synergistic effects of multiple drugs on the tumor. Objectives: In this study, we investigated the effect of combined exposure to bi-(AID-1-T), an anti-proliferative aptamer, and its analog bi-(AID-1-C), on the migratory activity of human GBM cells. Results: We examined the effects of various sequences of adding bi-(AID-1-T) and bi-(AID-1-C) on five human GBM cell cultures. Our findings indicate that certain sequences significantly reduced the ability of tumor cells to migrate and proliferate. Additionally, the expression of Nestin, PARP1, L1CAM, Caveolin-1, and c-Myc was downregulated in human GBM cells that survived exposure, suggesting that the treatment had a persistent antitumor effect on these cells.

Physiological and pathological roles of caveolins in the central nervous system

Caveolins are a family of transmembrane proteins located in caveolae, small lipid raft invaginations of the plasma membrane. The roles of caveolin-enriched lipid rafts are diverse, and include mechano-protection, lipid homeostasis, metabolism, transport, and cell signaling. Caveolin-1 (Cav-1) and other caveolins were described in endothelial cells and later in other cell types of the central nervous system (CNS), including neurons, astrocytes, oligodendrocytes, microglia, and pericytes. This pancellular presence of caveolins demands a better understanding of their functional roles in each cell type. In this review we describe the various functions of Cav-1 in the cells of normal and pathological brains. Several emerging preclinical findings suggest that Cav-1 could represent a potential therapeutic target in brain disorders.

A prognostic matrix gene expression signature defines functional glioblastoma phenotypes and niches

Background

Interactions among tumor, immune, and vascular niches play major roles in driving glioblastoma (GBM) malignancy and treatment responses. The composition, heterogeneity, and localization of extracellular core matrix proteins (CMPs) that mediate such interactions, however, are not well understood.

Methods

Here, through computational genomics and proteomics approaches, we analyzed the functional and clinical relevance of CMP expression in GBM at bulk, single cell, and spatial anatomical resolution.

Results

We identified genes encoding CMPs whose expression levels categorize GBM tumors into CMP expression-high (M-H) and CMP expression-low (M-L) groups. CMP enrichment is associated with worse patient survival, specific driver oncogenic alterations, mesenchymal state, infiltration of pro-tumor immune cells, and immune checkpoint gene expression. Anatomical and single-cell transcriptome analyses indicate that matrisome gene expression is enriched in vascular and leading edge/infiltrative niches that are known to harbor glioma stem cells driving GBM progression. Finally, we identified a 17-gene CMP expression signature, termed Matrisome 17 (M17) signature that further refines the prognostic value of CMP genes. The M17 signature is a significantly stronger prognostic factor compared to MGMT promoter methylation status as well as canonical subtypes, and importantly, potentially predicts responses to PD1 blockade.

Conclusion

The matrisome gene expression signature provides a robust stratification of GBM patients by survival and potential biomarkers of functionally relevant GBM niches that can mediate mesenchymal-immune cross talk. Patient stratification based on matrisome profiles can contribute to selection and optimization of treatment strategies.

mRNA markers for survival prediction in glioblastoma multiforme patients: a systematic review with bioinformatic analyses

BACKGROUND

Glioblastoma multiforme (GBM) is a type of fast-growing brain glioma associated with a very poor prognosis. This study aims to identify key genes whose expression is associated with the overall survival (OS) in patients with GBM.

METHODS

A systematic review was performed using PubMed, Scopus, Cochrane, and Web of Science up to Journey 2024. Two researchers independently extracted the data and assessed the study quality according to the New Castle Ottawa scale (NOS). The genes whose expression was found to be associated with survival were identified and considered in a subsequent bioinformatic study. The products of these genes were also analyzed considering protein-protein interaction (PPI) relationship analysis using STRING. Additionally, the most important genes associated with GBM patients' survival were also identified using the Cytoscape 3.9.0 software. For final validation, GEPIA and CGGA (mRNAseq_325 and mRNAseq_693) databases were used to conduct OS analyses. Gene set enrichment analysis was performed with GO Biological Process 2023.

RESULTS

From an initial search of 4104 articles, 255 studies were included from 24 countries. Studies described 613 unique genes whose mRNAs were significantly associated with OS in GBM patients, of which 107 were described in 2 or more studies. Based on the NOS, 131 studies were of high quality, while 124 were considered as low-quality studies. According to the PPI network, 31 key target genes were identified. Pathway analysis revealed five hub genes (IL6, NOTCH1, TGFB1, EGFR, and KDR). However, in the validation study, only, the FN1 gene was significant in three cohorts.

CONCLUSION

We successfully identified the most important 31 genes whose products may be considered as potential prognosis biomarkers as well as candidate target genes for innovative therapy of GBM tumors.

Impact of hypoxia on the molecular content of glioblastoma-derived exosomes

Hypoxia is a pathologic condition characterized by a tissue oxygen deficiency due to either decreased oxygen intake from outside and/or disruption of oxygen utilization in cells. This condition may arise when the oxygen demand exceeds its supply or the partial pressure of oxygen is below 10 mmHg. This situation poses a significant problem for glioblastoma (GBM) patients as it can activate angiogenesis, increase invasiveness and metastatic risk, prolong tumor survival, and suppress anti-tumor immunity, making hypoxic cells resistant to radiotherapy and chemotherapy. Low oxygen levels in tumors can cause severe cellular changes that can affect the release of extracellular vesicles (EVs), especially exosomes (EXOs), altering their proteomic profile both qualitatively and quantitatively. EXOs represent an adaptive response to hypoxic stress; therefore, they can be used to determine oxygen levels in cancer and assess its aggressiveness. They not only release signaling molecules to attract cells that promote the formation of small vessel walls but also send signals to other tumor cells that trigger their migration, which in turn plays a crucial role in the formation of metastases under hypoxia. This review investigates how the molecular profile of GBM-derived exosomes changes under hypoxic conditions, offering future possibilities for noninvasive diagnosis and monitoring of brain tumor patients.

A prognostic matrix code defines functional glioblastoma phenotypes and niches

Interactions among tumor, immune and vascular niches play major roles in driving glioblastoma (GBM) malignancy and treatment responses. The composition, heterogeneity, and localization of extracellular core matrix proteins (CMPs) that mediate such interactions, however, are not well understood. Here, we characterize functional and clinical relevance of genes encoding CMPs in GBM at bulk, single cell, and spatial anatomical resolution. We identify a "matrix code" for genes encoding CMPs whose expression levels categorize GBM tumors into matrisome-high and matrisome-low groups that correlate with worse and better patient survival, respectively. The matrisome enrichment is associated with specific driver oncogenic alterations, mesenchymal state, infiltration of pro-tumor immune cells and immune checkpoint gene expression. Anatomical and single cell transcriptome analyses indicate that matrisome gene expression is enriched in vascular and leading edge/infiltrative anatomic structures that are known to harbor glioma stem cells driving GBM progression. Finally, we identified a 17-gene matrisome signature that retains and further refines the prognostic value of genes encoding CMPs and, importantly, potentially predicts responses to PD1 blockade in clinical trials for GBM. The matrisome gene expression profiles provide potential biomarkers of functionally relevant GBM niches that contribute to mesenchymal-immune cross talk and patient stratification which could be applied to optimize treatment responses.

A prognostic matrix code defines functional glioblastoma phenotypes and niches

Interactions among tumor, immune and vascular niches play major roles in driving glioblastoma (GBM) malignancy and treatment responses. The composition, heterogeneity, and localization of extracellular core matrix proteins (CMPs) that mediate such interactions, however, are not well understood. Here, we characterize functional and clinical relevance of genes encoding CMPs in GBM at bulk, single cell, and spatial anatomical resolution. We identify a "matrix code" for genes encoding CMPs whose expression levels categorize GBM tumors into matrisome-high and matrisome-low groups that correlate with worse and better survival, respectively, of patients. The matrisome enrichment is associated with specific driver oncogenic alterations, mesenchymal state, infiltration of pro-tumor immune cells and immune checkpoint gene expression. Anatomical and single cell transcriptome analyses indicate that matrisome gene expression is enriched in vascular and leading edge/infiltrative anatomic structures that are known to harbor glioma stem cells driving GBM progression. Finally, we identified a 17-gene matrisome signature that retains and further refines the prognostic value of genes encoding CMPs and, importantly, potentially predicts responses to PD1 blockade in clinical trials for GBM. The matrisome gene expression profiles may provide biomarkers of functionally relevant GBM niches that contribute to mesenchymal-immune cross talk and patient stratification to optimize treatment responses.

SIWV tetrapeptide and ROS-responsive prodrug conjugate for advanced glioblastoma therapy

A new conjugate formulation, SIWV-PB-SN, based on glioblastoma (GBM)-homing SIWV tetrapeptide and an ROS-responsive prodrug is reported. SIWV-PB-SN selectively penetrates the GBM cells and releases anti-GBM drug (SN-38) via ROS-induced linker cleavage. This study presents a new insight for a more advanced therapeutic approach to overcoming GBM.