Functions In Glioblastoma Research Articles

Ursolic acid inhibits glioblastoma through suppressing TGFβ-mediated epithelial-mesenchymal transition (EMT) and angiogenesis

Found in many fruits and plants, Ursolic acid (UA), a pentacyclic triterpene that occurs naturally, is recognized for its anti-cancer effects, especially in combating glioblastoma. However, the intricate molecular mechanisms underpinning its anti-tumor actions are still not fully understood, despite the recognition of these effects. By examining the functions of epithelial-mesenchymal transition (EMT) and angiogenesis, crucial for glioblastoma progression, and their regulation through Transforming Growth Factor Beta (TGFβ) – a key marker for glioblastoma, our research aims to fill this knowledge gap. This study explores how ursolic acid can block the progression of glioblastoma by precisely targeting TGFβ-triggered EMT and angiogenesis. The findings show that UA successfully blocks the spread, movement, and invasion of glioblastoma cells. Accompanying this, there is a significant reduction in the expression of TGFβ and crucial EMT indicators like snail and vimentin. Furthermore, UA shows a reduction in angiogenesis that depends on the dosage, highlighted by decreased vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs). Interestingly, increased TGFβ expression in U87 and U251 glioblastoma cell lines was found to weaken UA's anti-tumor properties, shedding more light on TGFβ′s critical function in glioblastoma's pathology. Supporting these laboratory results, UA also showed considerable inhibition of tumor growth in a glioblastoma xenograft mouse model. Overall, our research emphasizes Ursolic acid's promise as a new treatment for glioblastoma and clarifies its action mechanism, mainly by inhibiting TGFβ signaling and thereby EMT and angiogenesis.

Early growth response 1 transcription factor and its context-dependent functions in glioblastoma.

Glioblastoma is the most aggressive form of primary brain tumour in adults. This tumour employs numerous transcription factors to advance and sustain its progression. Current evidence suggest that early growth response 1 (EGR1) plays a dual role as both an oncogene and a tumour suppressor in glioblastoma. Early growth response 1 expression is prevalent in glioblastoma, affecting over 80% of cases. Early growth response 1 regulatory roles extend to angiogenesis, cell adhesion, and resistance to chemotherapy, notably influencing pathways like hypoxia-inducible factor 1α and vascular endothelial growth factor A. Early growth response 1 can also induce cell adhesion, migration, chemoresistance against temozolomide, stemness, and self-renewal in glioblastoma cells. Despite its oncogenic functions, EGR1 can also suppress tumours by upregulating non-steroidal anti-inflammatory drug-activated gene 1 and phosphatase and tensin homolog deleted on chromosome ten, and inhibiting invasion and metastasis. Additionally, EGR1 may have hypothetical implications in the viral hit-and-run theory, particularly regarding cytomegalovirus infection. The key findings of this review are the context- dependent nature of EGR1's actions and its potential as a prognostic marker in glioblastoma. Further research is needed to understand EGR1's role fully and exploit its potential in clinics.

CTLA-4 blockade induces a microglia-Th1 cell partnership that stimulates microglia phagocytosis and anti-tumor function in glioblastoma

The limited efficacy of immunotherapies against glioblastoma underscores the urgency of better understanding immunity in the central nervous system. We found that treatment with αCTLA-4, but not αPD-1, prolonged survival in a mouse model of mesenchymal-like glioblastoma. This effect was lost upon the depletion of CD4+ Tcells but not CD8+ Tcells. αCTLA-4 treatment increased frequencies of intratumoral IFNγ-producing CD4+ Tcells, and IFNγ blockade negated the therapeutic impact of αCTLA-4. The anti-tumor activity of CD4+ Tcells did not require tumor-intrinsic MHC-II expression but rather required conventional dendritic cells as well as MHC-II expression on microglia. CD4+ Tcells interacted directly with microglia, promoting IFNγ-dependent microglia activation and phagocytosis via the AXL/MER tyrosine kinase receptors, which were necessary fortumor suppression. Thus, αCTLA-4 blockade in mesenchymal-like glioblastoma promotes a CD4+ Tcell-microgliacircuit wherein IFNγ triggers microglia activation and phagocytosis and microglia in turn act as antigen-presenting cells fueling the CD4+ Tcell response.

AXL is required for hypoxia-mediated hypoxia-inducible factor-1 alpha function in glioblastoma.

The online version contains supplementary material available at 10.1007/s43188-023-00195-z.

Abstract 2603: Investigating TUSC2 for its tumor suppressive functions in glioblastoma and its role in gliomagenesis

Abstract The role of Tumor Suppressor Candidate 2 (TUSC2) in glioblastoma (GBM) is still poorly understood. Our recent study (Cancer Letters, 2022) reported, for the first time, that TUSC2 functions as a novel tumor suppressor for GBM. In this report, we found TUSC2 protein expression, not mRNA expression, to be significantly decreased in GBM as compared to normal brain. TUSC2 protein is destabilized in GBM due to polyubiquitination by E3 ligase, neural precursor cell-expressed developmentally downregulated gene 4 (NEDD4), and degradation by the proteasome. We further identified that NEDD4 targets TUSC2 on lysine residue K71. We reported that TUSC2 overexpression reduces colony formation, neurosphere formation and promotes apoptosis in vitro, and suppresses tumor growth in vivo. Conversely, GBM cells with CRISPR-mediated knockout (KO) of TUSC2 were highly aggressive in vitro and in vivo, demonstrating the role of TUSC2 as a novel tumor suppressor for GBM. We further performed RNA-seq analysis using our stable Control gRNA and TUSC2-KO GBM cell lines and discovered over 1,200 significantly differentially expressed genes. Since TUSC2 is not a transcription factor, we hypothesized that TUSC2 alters the GBM transcriptome through protein-protein interaction with transcriptional regulators. In the current study, we tested this hypothesis by performing immunoprecipitation-mass spectrometry analysis to identify TUSC2-interacting proteins in both normal human astrocytes and GBM cell lines. Results showed 95 and 88 TUSC2-interacing proteins in astrocytes and GBM cell lines respectively. 27 proteins were found to interact with TUSC2 in both astrocytes and GBM. Ongoing efforts are focused to validate the interaction of TUSC2 with transcriptional regulators identified within the immunoprecipitation-mass spectrometry analysis. Since the expression of TUSC2 is lost in GBM, we hypothesized that TUSC2 loss is an important event during gliomagenesis. To test this hypothesis, we generated a novel conditional transgenic mouse model to investigate the role of TUSC2 loss in gliomagenesis. GFAP-Cre C57/BL6 mice were crossed with TUSC2flx/flx mice, mice containing loxp-flanked TUSC2, to specifically delete TUSC2 from mouse astrocytes. The recombination would introduce firefly luciferase to allow for bioluminescence imaging to detect TUSC2 knockout. Ongoing efforts are to monitor TUSC2flx/flx/GFAP-Cre (TUSC2-KO) mice for glioma development using IVIS imaging and MRI. Taken together, our study is the first step in elucidating the functions of a novel GBM tumor suppressor TUSC2 and investigating the role that TUSC2 plays in gliomagenesis. Citation Format: Austin Arrigo, Mariana Najjar, Angelina Regua, Hui-Wen Lo. Investigating TUSC2 for its tumor suppressive functions in glioblastoma and its role in gliomagenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2603.

NCOG-19. TUMOR INVASION INFLUENCES ON COGNITIVE FUNCTION IN RIGHT CEREBRAL HEMISPHERIC GLIOBLASTOMAS

Abstract INTRODUCTION Glioblastoma cells broadly infiltrate into surrounding brain parenchyma. In this study, we investigated the influence of tumor invasion on cognitive function in glioblastomas, using diffusion tensor imaging (DTI) . METHODS Participants were 32 patients with right hemispheric glioblastoma who underwent surgery in Kanazawa University Hospital (mean age, 61.8 years). We evaluated the differences in p-map and q-map, which represent diffusion isotropy and anisotropy with the patients' preoperative DTI. The patients were divided into two groups: less-invasive and highly-invasive types. Following clinical and demographic factors were collected retrospectively: age, sex, volume of enhanced lesion, tumor location, and methylation status of MGMT promoter. Several kinds of cognitive functions mediated by right cerebral hemisphere were assessed preoperatively. All these factors were compared between two groups. Moreover, voxel-based lesion symptom (VLSM) analyses were performed to investigate brain regions relate to decline of cognitive function by tumor invasion. RESULTS All clinical and demographic factors were not significantly different between two groups. Tumor cells significantly infiltrated to insula and basal ganglia in highly-invasive group. Verbal fluency, executive function, attention, and social cognition were impaired in highly-invasive group (p=0.0067, 0.036, 0.0064, and 0.030, respectively). Score of verbal fluency and social cognition were significantly lower when tumor infiltrated to the medial frontal region including cingulate cortex, and deep part of posterior middle and inferior frontal gyrus. Invasion to the sagittal stratum influenced on deterioration of attention and executive function. CONCLUSION The present study revealed that tumor invasion extending beyond the enhanced lesion causes deterioration of cognitive functions such as verbal fluency, executive function, attention, and social cognition in right hemispheric glioblastoma.

PUF60 promotes glioblastoma progression through regulation of EGFR stability

PUF60 (Poly (U) binding splicing factor 60 kDa), a nucleic acid-binding protein, has been shown to regulate transcription and links to tumorigenesis in various cancers. However, its biological role and function in glioblastoma remain unknown. In this study, we found that PUF60 is highly expressed in glioblastoma and correlated with poor prognosis. Furthermore, PUF60 knockdown significantly decreased the proliferation of glioblastoma cells in vitro and in vivo. Mechanistically, PUF60 could reduce the ubiquitination level of EGFR by transcriptionally regulating STUB1, an E3 ubiquitin ligase of EGFR, which lead to the activation of the EGFR-AKT pathway. Collectively, our study reveals the oncogenic role of PUF60 in glioblastoma and provides a potential therapeutic target for glioblastoma treatment.

Radiogenomics to characterize the immune-related prognostic signature associated with biological functions in glioblastoma.

The tumor microenvironment and immune cell infiltration (ICI) associated with glioblastoma (GBM) play a vital role in cancer development, progression, and prognosis. This study aimed to establish an ICI-related prognostic biomarker and explore the associations between ICI signatures and radiomic features in patients with GBM. The gene expression and survival data of patients with GBM were obtained from three databases. Based on the ICI pattern, an individualized ICI score for each GBM patient was developed in the discovery set (n = 400) and independently verified in the validation set (n = 374). A total of 5915 radiomic features were extracted from the intratumoral and peritumoral regions. Recursive feature elimination and support vector machine methods were performed to select the key features and generate a model predictive of low- or high- ICI scores. The prognostic value of the identified radio genomic model was examined in an independent dataset (n = 149) using imaging and survival data. We found that higher ICI scores often indicated worse patient prognosis (multivariable hazard ratio: 0.48 and 0.63 in discovery and validation set, respectively) and higher expression levels of immune checkpoint-related genes. A model that combined 11 radiomic features could well distinguish tumors with different ICI scores (AUC = 0.96, accuracy = 94%). This model was proven to be helpful for noninvasive prognostic stratification in an independent validation cohort. ICI scores may serve as an effective prognostic biomarker to characterize potential biological processes in patients with GBM. This ICI signature can be evaluated noninvasively through radiogenomic analysis. • Immune cell infiltration (ICI) scores can serve as an effective prognostic biomarker in patients with glioblastoma. • The ICI signature can be evaluated noninvasively through radiomic features derived from the intratumoral and peritumoral regions. • The prognostic value of the radiogenomic model can be verified by independent survival and MRI data.

Centromere protein J is overexpressed in human glioblastoma and promotes cell proliferation and migration.

Glioblastoma is the most common and malignant type of primary brain tumor. Previous studies have shown that alterations in centrosome amplification and its components are frequently found in treatment-resistant tumors and may be associated with tumor progression. A centrosome protein essential for centrosome biogenesis is the centromere protein J (CENPJ), known to control the proliferation of neural progenitors and hepatocarcinoma cells, and also neuronal migration. However, it remains unknown the role of CENPJ in glioblastoma. Here we show that CENPJ is overexpressed in human glioblastoma cell lines in comparison to human astrocytes. Using bioinformatics analysis, we find that high Cenpj expression is associated with poor prognosis in glioma patients. Examining Cenpj loss of function in glioblastoma by siRNA transfection, we find impairments in cell proliferation and migration. Using a Cenpj mutant version with the deleted PN2-3 or TCP domain, we found that a conserved PN2-3 region is required for glioblastoma migration. Moreover, Cenpj downregulation modulates glioblastoma morphology resulting in microtubules stabilization and actin filaments depolymerization. Altogether, our findings indicate that CENPJ controls relevant aspects of glioblastoma progression and might be a target for therapeutic intervention and a biomarker for glioma malignancy.

RNA modification patterns based on major RNA modifications define tumor microenvironment characteristics in glioblastoma

RNA modifications play a major role in tumorigenicity and progression, but the expression and function in glioblastoma (GBM) have not been well described. In this study, we developed a GBM score based on the differentially expressed genes (DEGs) between groups showing RNA modification patterns. We assessed the association between the GBM score and tumor microenvironment (TME) characteristics. Based on the gene expression of these regulators, we identified two clusters with distinct RNA modification patterns. Kaplan–Meier survival curves showed that patients in cluster 1 had worse survival than those in cluster 2. Kaplan–Meier and multivariate Cox regression analyses showed that GBM scores (based on DEGs between RNA modification patterns) are an independent predictive biomarker for patient prognosis. Besides, we found that samples with high scores were significantly associated with epithelial-to-mesenchymal transition and immune checkpoints, while samples with low scores were associated with cell cycle regulation. Importantly, GBM-score markedly positively correlated drug resistance, while negatively correlated with drug sensitive. The responders of anti-PD-1/PD-L1 immunotherapy tend to have a lower GBM score than non-responders. In conclusion, our comprehensive analysis of multiple RNA modifications in GBM revealed that RNA modification regulators were closely correlated with TME.

A functional role of S100A4/non-muscle myosin IIA axis for pro-tumorigenic vascular functions in glioblastoma

BackgroundGlioblastoma (GBM) is the most aggressive form of brain tumor and has vascular-rich features. The S100A4/non-muscle myosin IIA (NMIIA) axis contributes to aggressive phenotypes in a variety of human malignancies, but little is known about its involvement in GBM tumorigenesis. Herein, we examined the role of the S100A4/NMIIA axis during tumor progression and vasculogenesis in GBM.MethodsWe performed immunohistochemistry for S100A4, NMIIA, and two hypoxic markers, hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase 9 (CA9), in samples from 94 GBM cases. The functional impact of S100A4 knockdown and hypoxia were also assessed using a GBM cell line.ResultsIn clinical GBM samples, overexpression of S100A4 and NMIIA was observed in both non-pseudopalisading (Ps) and Ps (-associated) perinecrotic lesions, consistent with stabilization of HIF-1α and CA9. CD34(+) microvascular densities (MVDs) and the interaction of S100A4 and NMIIA were significantly higher in non-Ps perinecrotic lesions compared to those in Ps perinecrotic areas. In non-Ps perinecrotic lesions, S100A4(+)/HIF-1α(−) GBM cells were recruited to the surface of preexisting host vessels in the vascular-rich areas. Elevated vascular endothelial growth factor A (VEGFA) mRNA expression was found in S100A4(+)/HIF-1α(+) GBM cells adjacent to the vascular-rich areas. In addition, GBM patients with high S100A4 protein expression had significantly worse OS and PFS than did patients with low S100A4 expression. Knockdown of S100A4 in the GBM cell line KS-1 decreased migration capability, concomitant with decreased Slug expression; the opposite effects were elicited by blebbistatin-dependent inhibition of NMIIA.ConclusionS100A4(+)/HIF-1α(−) GBM cells are recruited to (and migrate along) preexisting vessels through inhibition of NMIIA activity. This is likely stimulated by extracellular VEGF that is released by S100A4(+)/HIF-1α(+) tumor cells in non-Ps perinecrotic lesions. In turn, these events engender tumor progression via acceleration of pro-tumorigenic vascular functions.-mzznLaNnzTzVPc8r2eojtVideo abstract

Radiogenomics to Characterize the Immune-Related Prognostic Signature Associated With Biological Functions in Glioblastoma

Radiogenomics to Characterize the Immune-Related Prognostic Signature Associated With Biological Functions in Glioblastoma

CYP1B1-AS1 Is a Novel Biomarker in Glioblastoma by Comprehensive Analysis.

Objective Growing evidence shows that enhancer RNAs (eRNAs) are pivotal for tumor progression. In this research, our team aimed to identify the survival-related eRNAs and further explore their potential function in glioblastoma (GBM). Methods RNA-sequencing data in 31 tumor types were acquired from TCGA datasets. The survival-related eRNAs were identified by the use of Kaplan-Meier survival analyses and Spearman's correlation analyses. KEGG pathway enrichment analysis was completed to investigate the underlying signal paths of the critical eRNA. Pancancer assays were applied to explore the association between CYP1B1-AS1 and CYP1B1. Results We identified 74 survival-related eRNAs and focused on CYP1B1-AS1 which displayed the greatest cor value. CYP1B1 was identified as a regulatory target of CYP1B1-AS1. KEGG analyses suggested that CYP1B1-AS1 might play an essential role through CK-CKR mutual effect, complement and coagulation cascades, TNF signal path, and JAK-STAT signal path. The pancancer verification outcomes revealed that CYP1B1-AS1 was related to survival in 4 cancers, i.e., LIHC, KIRP, KICH, and KIRC. Association was discovered between CYP1B1-AS1 and the targeted gene, CYP1B1, in 29 cancer types. Conclusion The outcomes herein provided the first evidence that overexpression of CYP1B1-AS1 might be a potential molecular biomarker for predicting the prognosis of patients with GBM.

RETRACTED: LncRNA PVT1 promotes tumorigenesis of glioblastoma by recruiting COPS5 to deubiquitinate and stabilize TRIM24

LncRNA PVT1 has been implicated in numerous pathophysiological processes and diseases, especially cancers. However, the role and mechanism of PVT1 in the tumorigenesis of glioblastoma remain unclear. We investigated the alteration of PVT1 and its key functions in glioblastoma. PVT1 was upregulated and associated with poor prognosis in glioblastoma. We demonstrated that PVT1 silencing suppressed cell proliferation, colony formation, and orthotopic xenograft tumor growth. Mechanistic investigations found that PVT1 interacted with TRIM24 directly and increased its protein stability. PVT1 recruited COPS5 to deubiquitinate TRIM24; reciprocally, PVT1 depletion impaired the interaction between COPS5 and TRIM24, resulting in decreased expression of TRIM24. PVT1, TRIM24, and COPS5 coordinately contributed to the activation of STAT3 signaling and malignant phenotype of glioblastoma. Collectively, this study elucidates the essential role of PVT1 in the tumorigenesis of glioblastoma, which provides candidacy therapeutic target for glioblastoma treatment.

Biologic Pathways Underlying Prognostic Radiomics Phenotypes from Paired MRI and RNA Sequencing in Glioblastoma.

Background The biologic meaning of prognostic radiomics phenotypes remains poorly understood, hampered in part by lack of multicenter reproducible evidence. Purpose To uncover the biologic meaning of individual prognostic radiomics phenotypes in glioblastomas using paired MRI and RNA sequencing data and to validate the reproducibility of the identified radiogenomics linkages externally. Materials and Methods This retrospective multicenter study included four data sets gathered between January 2015 and December 2016. From a radiomics analysis set, a 13-feature radiomics signature was built using preoperative MRI for overall survival prediction. Using a radiogenomics training set with both MRI and RNA sequencing, biologic pathways were enriched and correlated with each of the 13 radiomics phenotypes. Radiomics-correlated key genes were identified to derive a prognostic radiomics gene expression (RadGene) score. The reproducibility of identified pathways and genes was validated with an external test set and a public data set (The Cancer Genome Atlas [TCGA]). A log-rank test was performed to assess prognostic significance. Results A total of 435 patients (mean age, 55 years ± 15 [standard deviation]; 263 men) were enrolled. The radiomics signature was associated with overall survival (hazard ratio [HR], 3.68; 95% CI: 2.08, 6.52; P < .001) in the radiomics validation subset. Four types of prognostic radiomics phenotypes were correlated with distinct pathways: immune, proliferative, treatment responsive, and cellular functions (false-discovery rate < 0.10). Thirty radiomics-correlated genes were identified. The prognostic significance of the RadGene score was confirmed in an external test set (HR, 2.02; 95% CI: 1.19, 3.41; P = .01) and a TCGA test set (HR, 1.43; 95% CI: 1.001, 2.04; P = .048). The radiomics-associated pathways and key genes can be replicated in an external test set. Conclusion Individual radiomics phenotypes on MRI scans predictive of overall survival were driven by distinct key pathways involved in immune regulation, tumor proliferation, treatment responses, and cellular functions in glioblastoma, which could be reproduced externally. © RSNA, 2021 Online supplemental material is available for this article.

Construction of Novel Methylation-Driven Gene Model and Investigation of PARVB Function in Glioblastoma.

BackgroundGlioblastoma multiforme (GBM) is characterized by widespread genetic and transcriptional heterogeneity. Aberrant DNA methylation plays a vital role in GBM progression by regulating gene expression. However, little is known about the role of methylation and its association with prognosis in GBM. Our aim was to explore DNA methylation-driven genes (DMDGs) and provide evidence for survival prediction and individualized treatment of GBM patients.MethodsUse of the MethylMix R package identified DMDGs in GBM. The prognostic signature of DMDGs based on the risk score was constructed by multivariate Cox regression analysis. Receiver operating characteristics (ROC) curve and C-index were applied to assess the predictive performance of the DMDG prognostic signature. The predictive ability of the multigene signature model was validated in TCGA and CGGA cohorts. Finally, the role of DMDG β-Parvin (PARVB) was explored in vitro.ResultsThe prognostic signature of DMDGs was constructed based on six genes (MDK, NMNAT3, PDPN, PARVB, SERPINB1, and UPP1). The low-risk cohort had significantly better survival than the high-risk cohort (p < 0.001). The area under the curve of the ROC of the six-gene signature was 0.832, 0.927, and 0.980 within 1, 2, and 3 years, respectively. The C-index of 0.704 indicated superior specificity and sensitivity. The six-gene model has been demonstrated to be an independent prognostic factor for GBM. In addition, joint survival analysis indicated that the MDK, NMNAT3, PARVB, SERPINB1, and UPP1 genes were significantly associated with prognosis and therapeutic targets for GBM. Importantly, our DMDG prognostic model was more suitable and accurate for low-grade gliomas. Finally, we verified that PARVB induced epithelial-mesenchymal transition partially through the JAK2/STAT3 pathway, which in turn promoted GBM cell proliferation, migration, and invasion.ConclusionThis study demonstrated the potential value of the prognostic signature of DMDGs and provided important bioinformatic and potential therapeutic target data to facilitate individualized treatment for GBM, and to elucidate the specific mechanism by which PARVB promotes GBM progression.

Role of microRNAs in glioblastoma.

Glioblastoma is the most common and aggressive primary human brain cancer. MicroRNAs (miRNAs) are a set of small endogenous non-coding RNA molecules which play critical roles in different biological processes including cancer. The realization of miRNA regulatory functions in GBM has demonstrated that these molecules play a critical role in its initiation, progression and response to therapy. In this review we discuss the studies related to miRNA discovery and function in glioblastoma. We first summarize the typical miRNAs and their roles in GBM. Then we debate the potential for miRNA-based therapy for glioblastoma, including various delivery strategies. We surmise that future directions identified by these studies will point towards the necessity for therapeutic development and optimization to improve the outcomes for patients with glioblastoma.

ELTD1 deletion reduces vascular abnormality and improves T-cell recruitment after PD-1 blockade in glioma.

BackgroundTumor vessels in glioma are molecularly and functionally abnormal, contributing to treatment resistance. Proteins differentially expressed in glioma vessels can change vessel phenotype and be targeted for therapy. ELTD1 (Adgrl4) is an orphan member of the adhesion G-protein-coupled receptor family upregulated in glioma vessels and has been suggested as a potential therapeutic target. However, the role of ELTD1 in regulating vessel function in glioblastoma is poorly understood.MethodsELTD1 expression in human gliomas and its association with patient survival was determined using tissue microarrays and public databases. The role of ELTD1 in regulating tumor vessel phenotype was analyzed using orthotopic glioma models and ELTD1−/− mice. Endothelial cells isolated from murine gliomas were transcriptionally profiled to determine differentially expressed genes and pathways. The consequence of ELTD1 deletion on glioma immunity was determined by treating tumor-bearing mice with PD-1-blocking antibodies.ResultsELTD1 levels were upregulated in human glioma vessels, increased with tumor malignancy, and were associated with poor patient survival. Progression of orthotopic gliomas was not affected by ELTD1 deletion, however, tumor vascular function was improved in ELTD1−/− mice. Bioinformatic analysis of differentially expressed genes indicated increased inflammatory response and decreased proliferation in tumor endothelium in ELTD1−/− mice. Consistent with an enhanced inflammatory response, ELTD1 deletion improved T-cell infiltration in GL261-bearing mice after PD-1 checkpoint blockade.ConclusionOur data demonstrate that ELTD1 participates in inducing vascular dysfunction in glioma, and suggest that targeting of ELTD1 may normalize the vessels and improve the response to immunotherapy.

Musashi1 Contribution to Glioblastoma Development via Regulation of a Network of DNA Replication, Cell Cycle and Division Genes.

Simple SummaryGlioblastoma (GBM) is one of the most aggressive tumor types with no effective treatment options. To create new routes for therapy, it is necessary to continue mapping new pathways contributing to gliomagenesis. In this regard, there is growing evidence that RNA binding proteins (RBPs) are major contributors to expression alterations affecting genes in signaling pathways critical to GBM growth and response to therapy. We have established Musashi1 (Msi1) as a main player in GBM and medulloblastoma and as a marker of clinical outcome and response to therapy. Our genomic and functional analyses established that Msi1 directly and indirectly regulates the expression of a network of genes, promoting cell cycle progression and DNA replication. Ultimately, Msi1 impact on this network has important consequences in tumor initiation, growth and response to therapy.RNA-binding proteins (RBPs) function as master regulators of gene expression. Alterations in their levels are often observed in tumors with numerous oncogenic RBPs identified in recent years. Musashi1 (Msi1) is an RBP and stem cell gene that controls the balance between self-renewal and differentiation. High Msi1 levels have been observed in multiple tumors including glioblastoma and are often associated with poor patient outcomes and tumor growth. A comprehensive genomic analysis identified a network of cell cycle/division and DNA replication genes and established these processes as Msi1’s core regulatory functions in glioblastoma. Msi1 controls this gene network via two mechanisms: direct interaction and indirect regulation mediated by the transcription factors E2F2 and E2F8. Moreover, glioblastoma lines with Msi1 knockout (KO) displayed increased sensitivity to cell cycle and DNA replication inhibitors. Our results suggest that a drug combination strategy (Msi1 + cell cycle/DNA replication inhibitors) could be a viable route to treat glioblastoma.

ALYREF Drives Cancer Cell Proliferation Through an ALYREF-MYC Positive Feedback Loop in Glioblastoma.

BackgroundWhile RNA-binding proteins (RBPs) are known to affect RNA homeostasis during cancer cell initiation and development, their characteristics and biological function in glioblastoma (GBM) remain unclear.MethodsDifferences in RBP expression were explored by differential analysis of The Cancer Genome Atlas-GBM and Genotype-Tissue Expression (GTEx) datasets. Real-time PCR was conducted to verify the expressional levels of Aly/REF export factor (ALYREF) in normal brain and GBM tissues. Proliferative assays were performed to investigate molecular functions of ALYREF in GBM cells in vitro and in vivo. Real-time PCR and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed to analyze the ALYREF downstream signaling pathways. A chromatin immunoprecipitation (ChIP) assay was performed to identify key transcriptional factors that regulate ALYREF expression at RNA level. UV crosslinking, immunoprecipitation (CLIP) and RNA stability assays were conducted to reveal the bound RNAs and their stability regulated by ALYREF.ResultsThe results showed that ALYREF is frequently increased in GBM tissues, and its mRNA expression is regulated by the MYC proto-oncogene, bHLH transcription factor (MYC). Inhibition of ALYREF expression decreased GBM cell proliferative ability in vitro and tumor formation in vivo. KEGG analysis revealed that high ALYREF expression in GBM tissues was enriched in the upregulation of oncogenic pathways such as the Wnt/β-catenin signaling pathway. The CLIP assay showed that ALYREF drives GBM carcinogenesis by binding to and stabilizing MYC mRNAs. Overexpression of MYC restored the oncogenic property of ALYREF-deficient GBM cells.ConclusionOur data showed that ALYREF is regulated by MYC at the transcriptional level. ALYREF drives GBM cell proliferation by activating the Wnt/β-catenin signaling pathway and stabilizing MYC mRNA, suggesting that an ALYREF-MYC positive feedback loop might be a potential therapeutic target for treating GBM patients.