Contribution of Notch signaling activation to human glioblastoma multiforme

Genomic, epigenomic and transcriptomic landscape of glioblastoma

The mostly aggressive and extremely malignant type of central nervous system is Glioblastoma (GBM), which is characterized by an extremely short average survival time of lesser than 16 months. The primary cause of this phenomenon can be attributed to the extensively altered genome of GBM, which is characterized by the dysregulation of numerous critical signaling pathways and epigenetics regulations associated with proliferation, cellular growth, survival, and apoptosis. In light of this, different genetic alterations in critical signaling pathways and various epigenetics regulation mechanisms are associated with GBM and identified as distinguishing markers. Such GBM prognostic alterations are identified in PI3K/AKT, p53, RTK, RAS, RB, STAT3 and ZIP4 signaling pathways, metabolic pathway (IDH1/2), as well as alterations in epigenetic regulation genes (MGMT, CDKN2A-p16INK4aCDKN2B-p15INK4b). The exploration of innovative diagnostic and therapeutic approaches that specifically target these pathways is utmost importance to enhance the future medication for GBM. This study provides a comprehensive overview of dysregulated epigenetic mechanisms and signaling pathways due to mutations, methylation, and copy number alterations of in critical genes in GBM with prevalence and emphasizing their significance.

Emerging Therapies for Glioblastoma

Glioblastoma is most commonly a primary brain tumor and the utmost malignant one, with a survival rate of approximately 12-18 months. Glioblastoma is highly heterogeneous, demonstrating that different types of cells from the same tumor can manifest distinct gene expression patterns and biological behaviors. Conventional therapies such as temozolomide, radiation, and surgery have limitations. As of now, there is no cure for glioblastoma. Alternative treatment methods to eradicate glioblastoma are discussed in this review, including targeted therapies to PI3K, NFKβ, JAK-STAT, CK2, WNT, NOTCH, Hedgehog, and TGFβ pathways. The highly novel application of oncolytic viruses and nanomaterials in combating glioblastoma are also discussed. Despite scores of clinical trials for glioblastoma, the prognosis remains poor. Progress in breaching the blood-brain barrier with nanomaterials and novel avenues for targeted and combination treatments hold promise for the future development of efficacious glioblastoma therapies.

Deciphering Glioblastoma: Fundamental and Novel Insights into the Biology and Therapeutic Strategies of Gliomas

Gliomas constitute a diverse and complex array of tumors within the central nervous system (CNS), characterized by a wide range of prognostic outcomes and responses to therapeutic interventions. This literature review endeavors to conduct a thorough investigation of gliomas, with a particular emphasis on glioblastoma (GBM), beginning with their classification and epidemiological characteristics, evaluating their relative importance within the CNS tumor spectrum. We examine the immunological context of gliomas, unveiling the intricate immune environment and its ramifications for disease progression and therapeutic strategies. Moreover, we accentuate critical developments in understanding tumor behavior, focusing on recent research breakthroughs in treatment responses and the elucidation of cellular signaling pathways. Analyzing the most novel transcriptomic studies, we investigate the variations in gene expression patterns in glioma cells, assessing the prognostic and therapeutic implications of these genetic alterations. Furthermore, the role of epigenetic modifications in the pathogenesis of gliomas is underscored, suggesting that such changes are fundamental to tumor evolution and possible therapeutic advancements. In the end, this comparative oncological analysis situates GBM within the wider context of neoplasms, delineating both distinct and shared characteristics with other types of tumors.

Molecular signature of stem-like glioma cells (SLGCs) from human glioblastoma and gliosarcoma

Glioblastoma multiforme (GBM) and the GBM variant gliosarcoma (GS) are among the tumors with the highest morbidity and mortality, providing only palliation. Stem-like glioma cells (SLGCs) are involved in tumor initiation, progression, therapy resistance, and relapse. The identification of general features of SLGCs could contribute to the development of more efficient therapies. Commercially available protein arrays were used to determine the cell surface signature of eight SLGC lines from GBMs, one SLGC line obtained from a xenotransplanted GBM-derived SLGC line, and three SLGC lines from GSs. By means of non-negative matrix factorization expression metaprofiles were calculated. Using the cophenetic correlation coefficient (CCC) five metaprofiles (MPs) were identified, which are characterized by specific combinations of 7-12 factors. Furthermore, the expression of several factors, that are associated with GBM prognosis, GBM subtypes, SLGC differentiation stages, or neural identity was evaluated. The investigation encompassed 24 distinct SLGC lines, four of which were derived from xenotransplanted SLGCs, and included the SLGC lines characterized by the metaprofiles. It turned out that all SLGC lines expressed the epidermal growth factor EGFR and EGFR ligands, often in the presence of additional receptor tyrosine kinases. Moreover, all SLGC lines displayed a neural signature and the IDH1 wildtype, but differed in their p53 and PTEN status. Pearson Correlation analysis identified a positive association between the pluripotency factor Sox2 and the expression of FABP7, Musashi, CD133, GFAP, but not with MGMT or Hif1α. Spherical growth, however, was positively correlated with high levels of Hif1α, CDK4, PTEN, and PDGFRβ, whereas correlations with stemness factors or MGMT (MGMT expression and promoter methylation) were low or missing. Factors highly expressed by all SLGC lines, irrespective of their degree of stemness and growth behavior, are Cathepsin-D, CD99, EMMPRIN/CD147, Intβ1, the Galectins 3 and 3b, and N-Cadherin.

Eukaryotic initiation factor 4 A-3 promotes glioblastoma growth and invasion through the Notch1-dependent pathway

BACKGROUND

As an adult tumor with the most invasion and the highest mortality rate, the inherent heterogeneity of glioblastoma (GBM) is the main factor that causes treatment failure. Therefore, it is important to have a deeper understanding of the pathology of GBM. Some studies have shown that Eukaryotic Initiation Factor 4A-3 (EIF4A3) can promote the growth of many people's tumors, and the role of specific molecules in GBM remains unclear.

METHODS

The correlation between the expression of EIF4A3 gene and its prognosis was studied in 94 GBM patients using survival analysis. Further in vitro and in vivo experiments, the effect of EIF4A3 on GBM cells proliferation, migration, and the mechanism of EIF4A3 on GBM was explored. In addition, combined with bioinformatics analysis, we further confirmed that EIF4A3 contributes to the progress of GBM.

RESULTS

The expression of EIF4A3 was upregulated in GBM tissues, and high expression of EIF4A3 is associated with poor prognosis in GBM. In vitro, knockdown of EIF4A3 significantly reduced the proliferation, migration, and invasion abilities of GBM cells, whereas overexpression of EIF4A3 led to the opposite effect. The analysis of differentially expressed genes related to EIF4A3 indicates that it is involved in many cancer-related pathways, such as Notch and JAK-STAT3 signal pathway. In Besides, we demonstrated the interaction between EIF4A3 and Notch1 by RNA immunoprecipitation. Finally, the biological function of EIF4A3-promoted GBM was confirmed in living organisms.

CONCLUSION

The results of this study suggest that EIF4A3 may be a potential prognostic factor, and Notch1 participates in the proliferation and metastasis of GBM cells mediated by EIF4A3.

Biological functions of the Olig gene family in brain cancer and therapeutic targeting

The Olig genes encode members of the basic helix-loop-helix (bHLH) family of transcription factors. Olig1, Olig2, and Olig3 are expressed in both the developing and mature central nervous system (CNS) and regulate cellular specification and differentiation. Over the past decade extensive studies have established functional roles of Olig1 and Olig2 in development as well as in cancer. Olig2 overexpression drives glioma proliferation and resistance to radiation and chemotherapy. In this review, we summarize the biological functions of the Olig family in brain cancer and how targeting Olig family genes may have therapeutic benefit.

Regulation of Cell Plasticity by Bromodomain and Extraterminal Domain (BET) Proteins: A New Perspective in Glioblastoma Therapy

BET proteins are a family of multifunctional epigenetic readers, mainly involved in transcriptional regulation through chromatin modelling. Transcriptome handling ability of BET proteins suggests a key role in the modulation of cell plasticity, both in fate decision and in lineage commitment during embryonic development and in pathogenic conditions, including cancerogenesis. Glioblastoma is the most aggressive form of glioma, characterized by a very poor prognosis despite the application of a multimodal therapy. Recently, new insights are emerging about the glioblastoma cellular origin, leading to the hypothesis that several putative mechanisms occur during gliomagenesis. Interestingly, epigenome dysregulation associated with loss of cellular identity and functions are emerging as crucial features of glioblastoma pathogenesis. Therefore, the emerging roles of BET protein in glioblastoma onco-biology and the compelling demand for more effective therapeutic strategies suggest that BET family members could be promising targets for translational breakthroughs in glioblastoma treatment. Primarily, “Reprogramming Therapy”, which is aimed at reverting the malignant phenotype, is now considered a promising strategy for GBM therapy.

Hypocretin-1 suppresses malignant progression of glioblastoma cells through Notch1 signaling pathway

Hypocretin-1 is a multifunctional neuropeptide that has been identified as a potential antitumor agent for its role in inhibiting tumor growth, including in colon cancer, neuroendocrine tumor, and prostate cancer. However, the role and mechanism of hypocretin-1 in the occurrence and development of malignant glioma have not been well studied. Therefore, we investigated the effect of hypocretin-1 on glioblastoma proliferation, apoptosis, migration and invasion and its mechanism. We found that the hypocretin-1 receptor was expressed in both glioma cell lines and glioma tissues. Hypocretin-1 treatment can inhibit glioblastoma cell proliferation, migration and invasion, and induce cell apoptosis. Meanwhile, hypocretin-1 treatment significantly reduces tumor growth rate and tumor weight. In addition, mechanistic studies have found that hypocretin-1 exerts antitumor effects by inhibiting NOTCH signaling pathway. Overexpression of NICD significantly reversed the antitumor effect of hypocretin on glioblastoma. Taken together, these findings suggest that hypocretin-1 inhibits glioblastoma proliferation, migration and invasion and induces apoptosis in vitro and in vivo through NOTCH signaling pathway.

Fluoride in the Central Nervous System and Its Potential Influence on the Development and Invasiveness of Brain Tumours-A Research Hypothesis

The purpose of this review is to attempt to outline the potential role of fluoride in the pathogenesis of brain tumours, including glioblastoma (GBM). In this paper, we show for the first time that fluoride can potentially affect the generally accepted signalling pathways implicated in the formation and clinical course of GBM. Fluorine compounds easily cross the blood-brain barrier. Enhanced oxidative stress, disruption of multiple cellular pathways, and microglial activation are just a few examples of recent reports on the role of fluoride in the central nervous system (CNS). We sought to present the key mechanisms underlying the development and invasiveness of GBM, as well as evidence on the current state of knowledge about the pleiotropic, direct, or indirect involvement of fluoride in the regulation of these mechanisms in various tissues, including neural and tumour tissue. The effects of fluoride on the human body are still a matter of controversy. However, given the growing incidence of brain tumours, especially in children, and numerous reports on the effects of fluoride on the CNS, it is worth taking a closer look at these mechanisms in the context of brain tumours, including gliomas.

Pharmacological attributes of Bacopa monnieri extract: Current updates and clinical manifestation

Bacopa monnieri has been used for centuries in Ayurvedic medicine, alone or in combination with other herbs, as a memory and learning enhancer, sedative, and anti-epileptic. This review aimed to highlight the health benefits of B. monnieri extracts (BME), focusing on anti-cancer and neurodegenerative diseases. We examined the clinical studies on phytochemistry and pharmacological application of BME. We further highlighted the mechanism of action of these extracts in varying types of cancer and their therapeutic implications. In addition, we investigated the underlying molecular mechanism in therapeutic interventions, toxicities, safety concerns and synergistic potential in cognition and neuroprotection. Overall, this review provides deeper insights into the therapeutic implications of Brahmi as a lead formulation for treating neurological disorders and exerting cognitive-enhancing effects.

The Current State of Radiotherapy for Pediatric Brain Tumors: An Overview of Post-Radiotherapy Neurocognitive Decline and Outcomes

Tumors of the central nervous system are the most common solid malignancies diagnosed in children. While common, they are also found to have some of the lowest survival rates of all malignancies. Treatment of childhood brain tumors often consists of operative gross total resection with adjuvant chemotherapy or radiotherapy. The current body of literature is largely inconclusive regarding the overall benefit of adjuvant chemo- or radiotherapy. However, it is known that both are associated with conditions that lower the quality of life in children who undergo those treatments. Chemotherapy is often associated with nausea, emesis, significant fatigue, immunosuppression, and alopecia. While radiotherapy can be effective for achieving local control, it is associated with late effects such as endocrine dysfunction, secondary malignancy, and neurocognitive decline. Advancements in radiotherapy grant both an increase in lifetime survival and an increased lifetime for survivors to contend with these late effects. In this review, the authors examined all the published literature, analyzing the results of clinical trials, case series, and technical notes on patients undergoing radiotherapy for the treatment of tumors of the central nervous system with a focus on neurocognitive decline and survival outcomes.

Notch signaling in malignant gliomas: supporting tumor growth and the vascular environment

Glioblastoma is the most malignant form of glioma, which is the most commonly occurring tumor of the central nervous system. Notch signaling in glioblastoma is considered to be a marker of an undifferentiated tumor cell state, associated with tumor stem cells. Notch is also known for facilitating tumor dormancy escape, recurrence and progression after treatment. Studies in vitro suggest that reducing, removing or blocking the expression of this gene triggers tumor cell differentiation, which shifts the phenotype away from stemness status and consequently facilitates treatment. In contrast, in the vasculature, Notch appears to also function as an important receptor that defines mature non-leaking vessels, and increasing its expression promotes tumor normalization in models of cancer in vivo. Failures in clinical trials with Notch inhibitors are potentially related to their opposing effects on the tumor versus the tumor vasculature, which points to the need for a greater understanding of this signaling pathway.

The Role of Micro RNAs in Regulating PI3K/AKT Signaling Pathways in Glioblastoma

Glioblastoma is a type of brain cancer with aggressive and invasive nature. Such features result from increased proliferation and migration and also poor apoptosis of glioma cells leading to resistance to current treatments such as chemotherapy and radiotherapy. In recent studies, micro RNAs have been introduced as a novel target for treating glioblastoma via regulation of apoptotic signaling pathway, remarkably PI3K/AKT, which affect cellular functions and blockage or progression of the tumor. In this review, we focus on PI3K/AKT signaling pathway and other related apoptotic processes contributing to glioblastoma and investigate the role of micro RNAs interfering in apoptosis, invasion and proliferation of glioma through such apoptotic processes pathways. Databases NCBI, PubMed, and Web of Science were searched for published English articles using keywords such as 'miRNA OR microRNA', 'Glioblastoma', 'apoptotic pathways', 'PI3K and AKT', 'Caspase signaling Pathway' and 'Notch pathway'. Most articles were published from 7 May 2015 to 16 June 2020. This study focused on PI3K/AKT signaling pathway affecting glioma cells in separated subparts. Also, other related apoptotic pathways as the Caspase cycle and Notch have been also investigated. Nearly 40 miRNAs were found as tumor suppressors or onco-miRNA, and their targets, which regulated subcomponents participating in proliferation, invasion, and apoptosis of the tumoral cells. Our review reveals that miRNAs affect key molecules in signaling apoptotic pathways, partly PI3K/AKT, making them potential therapeutic targets to overcome the tumor. However, their utility as a novel treatment for glioblastoma requires further examination and investigation.

The multifaceted mechanisms of malignant glioblastoma progression and clinical implications

With the application of high throughput sequencing technologies at single-cell resolution, studies of the tumor microenvironment in glioblastoma, one of the most aggressive and invasive of all cancers, have revealed immense cellular and tissue heterogeneity. A unique extracellular scaffold system adapts to and supports progressive infiltration and migration of tumor cells, which is characterized by altered composition, effector delivery, and mechanical properties. The spatiotemporal interactions between malignant and immune cells generate an immunosuppressive microenvironment, contributing to the failure of effective anti-tumor immune attack. Among the heterogeneous tumor cell subpopulations of glioblastoma, glioma stem cells (GSCs), which exhibit tumorigenic properties and strong invasive capacity, are critical for tumor growth and are believed to contribute to therapeutic resistance and tumor recurrence. Here we discuss the role of extracellular matrix and immune cell populations, major components of the tumor ecosystem in glioblastoma, as well as signaling pathways that regulate GSC maintenance and invasion. We also highlight emerging advances in therapeutic targeting of these components.

Hippo Pathway in Regulating Drug Resistance of Glioblastoma

Glioblastoma (GBM) represents the most common and malignant tumor of the Central Nervous System (CNS), affecting both children and adults. GBM is one of the deadliest tumor types and it shows a strong multidrug resistance (MDR) and an immunosuppressive microenvironment which remain a great challenge to therapy. Due to the high recurrence of GBM after treatment, the understanding of the chemoresistance phenomenon and how to stimulate the antitumor immune response in this pathology is crucial. The deregulation of the Hippo pathway is involved in tumor genesis, chemoresistance and immunosuppressive nature of GBM. This pathway is an evolutionarily conserved signaling pathway with a kinase cascade core, which controls the translocation of YAP (Yes-Associated Protein)/TAZ (Transcriptional Co-activator with PDZ-binding Motif) into the nucleus, leading to regulation of organ size and growth. With this review, we want to highlight how chemoresistance and tumor immunosuppression work in GBM and how the Hippo pathway has a key role in them. We linger on the role of the Hippo pathway evaluating the effect of its de-regulation among different human cancers. Moreover, we consider how different pathways are cross-linked with the Hippo signaling in GBM genesis and the hypothetical mechanisms responsible for the Hippo pathway activation in GBM. Furthermore, we describe various drugs targeting the Hippo pathway. In conclusion, all the evidence described largely support a strong involvement of the Hippo pathway in gliomas progression, in the activation of chemoresistance mechanisms and in the development of an immunosuppressive microenvironment. Therefore, this pathway is a promising target for the treatment of high grade gliomas and in particular of GBM.

RBM8A Promotes Glioblastoma Growth and Invasion Through the Notch/STAT3 Pathway

Background

Glioblastoma (GBM) is a prevalent brain malignancy with an extremely poor prognosis, which is attributable to its invasive biological behavior. The RNA-binding motif protein 8A (RBM8A) has different effects on various human cancers. However, the role of RBM8A in GBM progression remains unclear.

Methods

We investigated the expression levels of RBM8A in 94 GBM patients and explored the correlation between RBM8A expression and patient prognosis. Using in vitro and in vivo assays, combined with GBM sequencing data from the Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA), we examined whether and how RBM8A contributes to GBM progression.

Results

RBM8A was up-regulated in GBM tissues, and its higher expression correlated with worse prognosis. Knockdown of RBM8A inhibited GBM progression and invasion ability both in vitro and in vivo. On the contrary, overexpression of RBM8A promoted GBM progression and invasion ability. Enrichment analysis of differentially expressed genes in GBM data identified the Notch1/STAT3 network as a potential downstream target of RBM8A, and this was supported by molecular docking studies. Furthermore, we demonstrated that RBM8A regulates the transcriptional activity of CBF1. The γ-secretase inhibitor DAPT significantly reversed RBM8A-enhanced GBM cell proliferation and invasion, and was associated with down-regulation of p-STAT3 and Notch1 protein. Finally, the gene set variance analysis score of genes involved in regulation of the Notch1/STAT3 network by RBM8A showed good diagnostic and prognostic value for GBM.

Conclusions

RBM8A may promote GBM cell proliferation and migration by activating the Notch/STAT3 pathway in GBM cells, suggesting that RBM8A may serve as a potential therapeutic target for the treatment of GBM.

A Phase II and Pharmacodynamic Trial of RO4929097 for Patients With Recurrent/Progressive Glioblastoma

BACKGROUND

Cancer stem-like cells are a major cause of resistance to therapy in patients with glioblastoma (GBM) as well as other cancers. Tumor cells are maintained in a stem-like proliferative state in large part through the Notch signaling pathway. The function of this pathway in turn depends on gamma secretase activity. Inhibition of this enzyme therefore inhibits the Notch pathway and tumor growth as measured by a reduction in the formation of brain tumor neurospheres in murine models. RO4929097 is an oral gamma secretase inhibitor.

OBJECTIVE

To estimate the 6-mo progression-free survival rate (PFS6) in patients with progressive GBM and to inhibit by 50% the generation of neurospheres in fresh tissue resected from patients treated with RO4929097.

METHODS

In this phase II and pharmacodynamic study, patients with recurrent GBM received RO4929097 in a study of 2 groups. Group A patients had unresectable disease and received drug in a standard phase II design. Group B patients had resectable disease and received drug before and after surgical resection. Endpoints included PFS6 and the inhibition of neurosphere formation in the resected tumor samples.

RESULTS

A total of 47 patients received treatment, 7 of whom had tumor resection. The PFS6 was 4%, and the inhibition of neurosphere formation occurred in 1 of 7 patient samples.

CONCLUSION

RO4929097 was inactive in recurrent GBM patients and demonstrated minimal inhibition of neurosphere formation in fresh tissue samples.

Functional Gene Expression Differentiation of the Notch Signaling Pathway in Female Reproductive Tract Tissues-A Comprehensive Review With Analysis

The Notch pathway involves evolutionarily conserved signaling regulating the development of the female tract organs such as breast, ovary, cervix, and uterine endometrium. A great number of studies revealed Notch aberrancies in association with their carcinogenesis and disease progression, the management of which is still challenging. The present study is a comprehensive review of the available literature on Notch signaling during the normal development and carcinogenesis of the female tract organs. The review has been enriched with our analyses of the TCGA data including breast, cervical, ovarian, and endometrial carcinomas concerning the effects of Notch signaling at two levels: the core components and downstream effectors, hence filling the lack of global overview of Notch-driven carcinogenesis and disease progression. Phenotype heterogeneity regarding Notch signaling was projected in two uniform manifold approximation and projection algorithm dimensions, preceded by the principal component analysis step reducing the data burden. Additionally, overall and disease-free survival analyses were performed with the optimal cutpoint determination by Evaluate Cutpoints software to establish the character of particular Notch components in tumorigenesis. In addition to the review, we demonstrated separate models of the examined cancers of the Notch pathway and its targets, although expression profiles of all normal tissues were much more similar to each other than to its cancerous compartments. Such Notch-driven cancerous differentiation resulted in a case of opposite association with DFS and OS. As a consequence, target genes also show very distinct profiles including genes associated with cell proliferation and differentiation, energy metabolism, or the EMT. In conclusion, the observed Notch associations with the female tract malignancies resulted from differential expression of target genes. This may influence a future analysis to search for new therapeutic targets based on specific Notch pathway profiles.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

TRPM7 Induces Tumorigenesis and Stemness Through Notch Activation in Glioma

We have reported that transient receptor potential melastatin-related 7 (TRPM7) regulates glioma stem cells (GSC) growth and proliferation through Notch, STAT3-ALDH1, and CD133 signaling pathways. In this study, we determined the major contributor(s) to TRPM7 mediated glioma stemness by further deciphering each individual Notch signaling. We first determined whether TRPM7 is an oncotarget in glioblastoma multiforme (GBM) using the Oncomine database. Next, we determined whether TRPM7 silencing by siRNA TRPM7 (siTRPM7) induces cell growth arrest or apoptosis to reduce glioma cell proliferation using cell cycle analysis and annexin V staining assay. We then examined the correlations between the expression of TRPM7 and Notch signaling activity as well as the expression of GSC markers CD133 and ALDH1 in GBM by downregulating TRPM7 through siTRPM7 or upregulating TRPM7 through overexpression of human TRPM7 (M7-wt). To distinguish the different function of channel and kinase domain of TRPM7, we further determined how the α-kinase-dead mutants of TRPM7 (α-kinase domain deleted/M7-DK and K1648R point mutation/M7-KR) affect Notch activities and CD133 and ALDH1 expression. Lastly, we determined the changes in TRPM7-mediated regulation of glioma cell growth/proliferation, cell cycle, and apoptosis by targeting Notch1. The Oncomine data revealed a significant increase in TRPM7 mRNA expression in anaplastic astrocytoma, diffuse astrocytoma, and GBM patients compared to that in normal brain tissues. TRPM7 silencing reduced glioma cell growth by inhibiting cell entry into S and G2/M phases and promoting cell apoptosis. TRPM7 expression in GBM cells was found to be positively correlated with Notch1 signaling activity and CD133 and ALDH1 expression; briefly, downregulation of TRPM7 by siTRPM7 decreased Notch1 signaling whereas upregulation of TRPM7 increased Notch1 signaling. Interestingly, kinase-inactive mutants (M7-DK and M7-KR) resulted in reduced activation of Notch1 signaling and decreased expression of CD133 and ALDH1 compared to that of wtTRPM7. Finally, targeting Notch1 effectively suppressed TRPM7-induced growth and proliferation of glioma cells through cell G1/S arrest and apoptotic induction. TRPM7 is responsible for sustained Notch1 signaling activation, enhanced expression of GSC markers CD133 and ALDH1, and regulation of glioma stemness, which contributes to malignant glioma cell growth and invasion.

Loss of PLK2 induces acquired resistance to temozolomide in GBM via activation of notch signaling

Background

Glioblastoma (GBM) is a lethal type of primary brain tumor with a median survival less than 15 months. Despite the recent improvements of comprehensive strategies, the outcomes for GBM patients remain dismal. Accumulating evidence indicates that rapid acquired chemoresistance is the major cause of GBM recurrence thus leads to worse clinical outcomes. Therefore, developing novel biomarkers and therapeutic targets for chemoresistant GBM is crucial for long-term cures.

Methods

Transcriptomic profiles of glioblastoma were downloaded from gene expression omnibus (GEO) and TCGA database. Differentially expressed genes were analyzed and candidate gene PLK2 was selected for subsequent validation. Clinical samples and corresponding data were collected from our center and measured using immunohistochemistry analysis. Lentiviral transduction and in vivo xenograft transplantation were used to validate the bioinformatic findings. GSEA analyses were conducted to identify potential signaling pathways related to PLK2 expression and further confirmed by in vitro mechanistic assays.

Results

In this study, we identified PLK2 as an extremely suppressed kinase-encoding gene in GBM samples, particularly in therapy resistant GBM. Additionally, reduced PLK2 expression implied poor prognosis and TMZ resistance in GBM patients. Functionally, up-regulated PLK2 attenuated cell proliferation, migration, invasion, and tumorigenesis of GBM cells. Besides, exogenous overexpression of PLK2 reduced acquired TMZ resistance of GBM cells. Furthermore, bioinformatics analysis indicated that PLK2 was negatively correlated with Notch signaling pathway in GBM. Mechanically, loss of PLK2 activated Notch pathway through negative transcriptional regulation of HES1 and degradation of Notch1.

Conclusion

Loss of PLK2 enhances aggressive biological behavior of GBM through activation of Notch signaling, indicating that PLK2 could be a prognostic biomarker and potential therapeutic target for chemoresistant GBM.

RBPJ contributes to the malignancy of glioblastoma and induction of proneural-mesenchymal transition via IL-6-STAT3 pathway

Notch signaling plays a pivotal role in many cancers, including glioblastoma (GBM). Recombination signal binding protein for immunoglobulin kappa J region (RBPJ) is a key transcription factor of the Notch signaling pathway. Here, we interrogated the function of RBPJ in GBM. Firstly, RBPJ expression of GBM samples was examined. Then, we knocked down RBPJ expression in 2 GBM cell lines (U251 and T98) and 4 glioblastoma (GBM) stem-like cell lines derived from surgical samples of GBM (KGS01, KGS07, KGS10 and KGS15) to investigate the effect on cell proliferation, invasion, stemness, and tumor formation ability. Expression of possible downstream targets of RBPJ was also assessed. RBPJ was overexpressed in the GBM samples, downregulation of RBPJ reduced cell proliferation and the invasion ability of U251 and T98 cells and cell proliferation ability and stemness of glioblastoma stem-like cells (GSC) lines. These were accompanied by reduced IL-6 expression, reduced activation of STAT3, and inhibited proneural-mesenchymal transition (PMT). Tumor formation and PMT were also impaired by RBPJ knockdown in vivo. In conclusion, RBPJ promotes cell proliferation, invasion, stemness, and tumor initiation ability in GBM cells through enhanced activation of IL-6-STAT3 pathway and PMT, inhibition of RBPJ may constitute a prospective treatment for GBM.

Targeting the Epithelial-to-Mesenchymal Transition in Cancer Stem Cells for a Better Clinical Outcome of Glioma

Glioma is one of the most common malignant tumors of the central nervous system with a poor prognosis at present due to lack of effective treatment options. Its initiation, migration, and multipotency are affected by cancer stem cell’s transition. Previous studies imply that changes in the cancer stem cells can affect the malignant differentiation of the tumor. We found that the epithelial-to-mesenchymal transition (EMT)-related regulatory pathway is an important target for tumor therapy. In this review, we discuss the transition factor of EMT and 3 specific pathways that affect the EMT of cancer stem cells during tumor development. We conclude that targeting the EMT process of cancer stem cells can be a feasible approach in the treatment of glioma.

Tenascin-C Function in Glioma: Immunomodulation and Beyond

First identified in the 1980s, tenascin-C (TNC) is a multi-domain extracellular matrix glycoprotein abundantly expressed during the development of multicellular organisms. TNC level is undetectable in most adult tissues but rapidly and transiently induced by a handful of pro-inflammatory cytokines in a variety of pathological conditions including infection, inflammation, fibrosis, and wound healing. Persistent TNC expression is associated with chronic inflammation and many malignancies, including glioma. By interacting with its receptor integrin and a myriad of other binding partners, TNC elicits context- and cell type-dependent function to regulate cell adhesion, migration, proliferation, and angiogenesis. TNC operates as an endogenous activator of toll-like receptor 4 and promotes inflammatory response by inducing the expression of multiple pro-inflammatory factors in innate immune cells such as microglia and macrophages. In addition, TNC drives macrophage differentiation and polarization predominantly towards an M1-like phenotype. In contrast, TNC shows immunosuppressive function in T cells. In glioma, TNC is expressed by tumor cells and stromal cells; high expression of TNC is correlated with tumor progression and poor prognosis. Besides promoting glioma invasion and angiogenesis, TNC has been found to affect the morphology and function of tumor-associated microglia/macrophages in glioma. Clinically, TNC can serve as a biomarker for tumor progression; and TNC antibodies have been utilized as an adjuvant agent to deliver anti-tumor drugs to target glioma. A better mechanistic understanding of how TNC impacts innate and adaptive immunity during tumorigenesis and tumor progression will open new therapeutic avenues to treat brain tumors and other malignancies.

Integrin Beta 1 Promotes Glioma Cell Proliferation by Negatively Regulating the Notch Pathway

In this study, genes associated with the Notch signaling pathway in gliomas were analyzed using bioinformatics and in vitro experiments. The dataset GSE22772 was downloaded from the Gene-Cloud of Biotechnology Information database. Differentially expressed genes (DEGs) between short hairpin RNA (shRNA) intervening glioma cells and control cells were screened using the unpaired t test. Functional enrichment analysis was performed, and coexpression network was analyzed to identify the most important genes associated with the Notch signaling pathway. Integrin beta 1 (ITGB1) mRNA and protein levels in clinical glioma tumor samples and tumor adjacent normal tissue samples were analyzed using quantitative real-time PCR and immunohistochemistry, respectively. The relationship between ITGB1 expression and the prognosis of patients with gliomas was analyzed using the Kaplan-Meier curve. ITGB1 interference expression cell line U87 and ITGB1 overexpressing cell line were established using sh-ITGB1 and oe-ITGB1 plasmids, respectively. MTT and colony formation assays were used to detect changes in the proliferation of glioma cells. Moreover, western blotting was used to detect the expression of Notch and Hey1. A total of 7,962 DEGs were screened between shRNA intervening glioma cells and control cells, which were mainly associated with spliceosome, proteoglycans in cancer, focal adhesion, and the Notch signaling pathway. ITGB1 showed the highest expression in the coexpression network. The mRNA and protein expression of ITGB1 in glioma tumor samples was significantly higher than that in tumor adjacent normal tissue samples (p < 0.05). Overall survival time of patients in the ITGB1 low-expression group was significantly longer than that in the ITGB1 high-expression group, indicating that ITGB1 expression negatively correlated with the prognosis. Fluorescence microscopy, qRT-PCR, and western blotting confirmed the transfection efficiency of ITGB1 overexpression and interference expression in U251 and U87 cells. The MTT and colony formation assays indicated that U87 cell proliferation was significantly inhibited after intervention with ITGB1 (p < 0.05), and overexpression of ITGB1 significantly promoted U251 cell proliferation (p < 0.05). In addition, the expression of Notch and Hey1 proteins was significantly decreased after ITGB1 intervention (p < 0.05), and their expression was significantly upregulated after ITGB1 overexpression (p < 0.05). ITGB1 expression in glioma tissues was significantly higher than that in adjacent normal tissues and was negatively correlated with the survival time of patients. Therefore, ITGB1 can significantly promote proliferation of glioma cells via feedback regulation of the Notch signaling pathway.

Transcriptome analysis of duck embryo fibroblasts for the dynamic response to duck tembusu virus infection and dual regulation of apoptosis genes

Duck Tembusu virus (DTMUV) is an emerging pathogenic flavivirus that has caused enormous economic losses in Southeast Asia. However, the pathogenic mechanism and host's responses after DTMUV infection remain poorly understood. During this study, total mRNA sequencing (RNA-Seq) analysis was used to detect the global gene expression in DEFs at various time points after DTMUV infection. We identified 326 genes altered significantly at all time points, and these genes were dynamically enriched in multifarious biological processes, including apoptosis, innate immune response, DNA replication, cell cycle arrest and DNA repair. Next, the results showed that apoptosis was induced and the proportion of apoptosis increased with time, and pro-apoptotic molecules caspases were activated. The RNA-seq data analysis further revealed that most pro-apoptosis and anti-apoptosis genes were early continually responsive, and the genes involved in both intrinsic and extrinsic apoptotic pathways were initiated. Further, the considerably enriched immune-relevant pathways were involved in apoptosis process, and protein-protein interactions (PPIs) analysis showed that IL6, STAT1, TNFAIP3, CFLAR and PTGS2 may be key regulators of DEFs apoptosis. In conclusion, this study not only contributes to understanding the underlying mechanism of DEFs infection with DTMUV, but also provides new insights into targets screening for antiviral therapy.

Leptin and Notch Signaling Cooperate in Sustaining Glioblastoma Multiforme Progression

Glioblastoma multiforme (GBM) is the most malignant form of glioma, which represents one of the commonly occurring tumors of the central nervous system. Despite the continuous development of new clinical therapies against this malignancy, it still remains a deadly disease with very poor prognosis. Here, we demonstrated the existence of a biologically active interaction between leptin and Notch signaling pathways that sustains GBM development and progression. We found that the expression of leptin and its receptors was significantly higher in human glioblastoma cells, U-87 MG and T98G, than in a normal human glial cell line, SVG p12, and that activation of leptin signaling induced growth and motility in GBM cells. Interestingly, flow cytometry and real-time RT-PCR assays revealed that GBM cells, grown as neurospheres, displayed stem cell-like properties (CD133+) along with an enhanced expression of leptin receptors. Leptin treatment significantly increased the neurosphere forming efficiency, self-renewal capacity, and mRNA expression levels of the stemness markers CD133, Nestin, SOX2, and GFAP. Mechanistically, we evidenced a leptin-mediated upregulation of Notch 1 receptor and the activation of its downstream effectors and target molecules. Leptin-induced effects on U-87 MG and T98G cells were abrogated by the selective leptin antagonist, the peptide LDFI (Leu-Asp-Phe-Ile), as well as by the specific Notch signaling inhibitor, GSI (Gamma Secretase Inhibitor) and in the presence of a dominant-negative of mastermind-like-1. Overall, these findings demonstrate, for the first time, a functional interaction between leptin and Notch signaling in GBM, highlighting leptin/Notch crosstalk as a potential novel therapeutic target for GBM treatment.

Subtype-specific signaling pathways and genomic aberrations associated with prognosis of glioblastoma

Background

A high heterogeneity and activation of multiple oncogenic pathways have been implicated in failure of targeted therapies in glioblastoma (GBM).

Methods

Using The Cancer Genome Atlas data, we identified subtype-specific prognostic core genes by a combined approach of genome-wide Cox regression and Gene Set Enrichment Analysis. The results were validated with 8 combined public datasets containing 608 GBMs. We further examined prognostic chromosome aberrations and mutations.

Results

In classical and mesenchymal subtypes, 2 receptor tyrosine kinases (RTKs) (MET and IGF1R), and the genes in RTK downstream pathways such as phosphatidylinositol-3 kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), and nuclear factor-kappaB (NF-kB), were commonly detected as prognostic core genes. Classical subtype-specific prognostic core genes included those in cell cycle, DNA repair, and the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway. Immune-related genes were enriched in the prognostic genes showing negative promoter cytosine-phosphate-guanine (CpG) methylation/expression correlations. Mesenchymal subtype-specific prognostic genes were those related to mesenchymal cell movement, PI3K/Akt, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), Wnt/β-catenin, and Wnt/Ca2+ pathways. In copy number alterations and mutations, 6p loss and TP53 mutation were associated with poor and good survival, respectively, in the classical subtype. In the mesenchymal subtype, patients with PIK3R1 or PCLO mutations showed poor prognosis. In the glioma CpG island methylator phenotype (G-CIMP) subtype, patients harboring 10q loss, 12p gain, or 14q loss exhibited poor survival. Furthermore, 10q loss was significantly associated with the recently recognized G-CIMP subclass showing relatively low CpG methylation and poor prognosis.

Conclusion

These subtype-specific alterations have promising potentials as new prognostic biomarkers and therapeutic targets combined with surrogate markers of GBM subtypes. However, considering the small number of events, the results of copy number alterations and mutations require further validations.

The Role of a Neurovascular Signaling Pathway Involving Hypoxia-Inducible Factor and Notch in the Function of the Central Nervous System

In the neurovascular unit, the neuronal and vascular systems communicate with each other. O₂ and nutrients, reaching endothelial cells (ECs) through the blood stream, spread into neighboring cells, such as neural stem cells, and neurons. The proper function of neural circuits in adults requires sufficient O₂ and glucose for their metabolic demands through angiogenesis. In a central nervous system (CNS) injury, such as glioma, Parkinson’s disease, and Alzheimer’s disease, damaged ECs can contribute to tissue hypoxia and to the consequent disruption of neuronal functions and accelerated neurodegeneration. This review discusses the current evidence regarding the contribution of oxygen deprivation to CNS injury, with an emphasis on hypoxia-inducible factor (HIF)-mediated pathways and Notch signaling. Additionally, it focuses on adult neurological functions and angiogenesis, as well as pathological conditions in the CNS. Furthermore, the functional interplay between HIFs and Notch is demonstrated in pathophysiological conditions.

Emerging Role of Cellular Prion Protein in the Maintenance and Expansion of Glioma Stem Cells

Cellular prion protein (PrP^C) is a membrane-anchored glycoprotein representing the physiological counterpart of PrP scrapie (PrP^Sc), which plays a pathogenetic role in prion diseases. Relatively little information is however available about physiological role of PrP^C. Although PrP^C ablation in mice does not induce lethal phenotypes, impairment of neuronal and bone marrow plasticity was reported in embryos and adult animals. In neurons, PrP^C stimulates neurite growth, prevents oxidative stress-dependent cell death, and favors antiapoptotic signaling. However, PrP^C activity is not restricted to post-mitotic neurons, but promotes cell proliferation and migration during embryogenesis and tissue regeneration in adult. PrP^C acts as scaffold to stabilize the binding between different membrane receptors, growth factors, and basement proteins, contributing to tumorigenesis. Indeed, ablation of PrP^C expression reduces cancer cell proliferation and migration and restores cell sensitivity to chemotherapy. Conversely, PrP^C overexpression in cancer stem cells (CSCs) from different tumors, including gliomas—the most malignant brain tumors—is predictive for poor prognosis, and correlates with relapses. The mechanisms of the PrP^C role in tumorigenesis and its molecular partners in this activity are the topic of the present review, with a particular focus on PrP^C contribution to glioma CSCs multipotency, invasiveness, and tumorigenicity.

Modulation of cancer cell signaling by long noncoding RNAs

Cellular signaling pathways play a very important role in almost all molecular processes in the cell, and are generally composed of a complex set of cascades in which enzymes and proteins play a key role. These signaling pathways include different types of cellular signaling classified based on their receptors and effector proteins such as enzyme-linked receptors, cytokine receptors, and G-protein-coupled receptors each of which is subdivided into different classes. Signaling pathways are tightly controlled by different mechanisms mostly thorough inhibiting/activating their receptors or effector proteins. In the last two decades, our knowledge of molecular biology has changed dramatically and today we know that more than 85% of the human genome expresses noncoding RNAs most of which are crucial in the cellular and molecular mechanisms of cells. One of these noncoding RNAs are long noncoding RNAs (lncRNA) containing more than 200 nucleotides. LncRNAs participate in the progression of cancer growth through several mechanism including signaling pathways. In this review, we summarize some of the most important of lncRNAs and their effect on important signaling pathways.

Noncoding RNAs in Calcific Aortic Valve Disease: A Review of Recent Studies

Calcific aortic valve disease (CAVD) is the most common heart valve disorder in human populations. Nevertheless, there are presently no effective means for its prevention and treatment. It is therefore critical to comprehensively define key mechanisms of the disease. A major focus of cardiovascular research has been characterization of how regulation of gene expression maintains healthy physiologic status of the component tissues of the system and how derangements of gene regulation may become pathological. Recently, substantial evidence has emerged that noncoding RNAs, which are an enormous and versatile class of regulatory elements, such as microRNAs and long noncoding RNAs, have roles in onset and prognosis of CAVD. Authors of the present report have therefore here provided a summary of the current understanding of contributions made by noncoding RNAs major features of CAVD. It is anticipated that this article will serve as a valuable guide to research strategy in this field and may additionally provide both researchers and clinicians with an expanded range of CAVD-associated biomarkers.

Role of Notch Signaling Pathway in Glioblastoma Pathogenesis

Notch signaling is an evolutionarily conserved pathway that regulates important biological processes, such as cell proliferation, apoptosis, migration, self-renewal, and differentiation. In mammals, Notch signaling is composed of four receptors (Notch1–4) and five ligands (Dll1-3–4, Jagged1–2) that mainly contribute to the development and maintenance of the central nervous system (CNS). Neural stem cells (NSCs) are the starting point for neurogenesis and other neurological functions, representing an essential aspect for the homeostasis of the CNS. Therefore, genetic and functional alterations to NSCs can lead to the development of brain tumors, including glioblastoma. Glioblastoma remains an incurable disease, and the reason for the failure of current therapies and tumor relapse is the presence of a small subpopulation of tumor cells known as glioma stem cells (GSCs), characterized by their stem cell-like properties and aggressive phenotype. Growing evidence reveals that Notch signaling is highly active in GSCs, where it suppresses differentiation and maintains stem-like properties, contributing to Glioblastoma tumorigenesis and conventional-treatment resistance. In this review, we try to give a comprehensive view of the contribution of Notch signaling to Glioblastoma and its possible implication as a target for new therapeutic approaches.

Aberrant miRNAs Regulate the Biological Hallmarks of Glioblastoma

GBM is the highest incidence in primary intracranial malignancy, and it remains poor prognosis even though the patient is gave standard treatment. Despite decades of intense research, the complex biology of GBM remains elusive. In view of eight hallmarks of cancer which were proposed in 2011, studies related to the eight biological capabilities in GBM have made great progress. From these studies, it can be inferred that miRs, as a mode of post-transcriptional regulation, are involved in regulating these malignant biological hallmarks of GBM. Herein, we discuss state-of-the-art research on how aberrant miRs modulate the eight hallmarks of GBM. The upregulation of 'oncomiRs' or the genetic loss of tumor suppressor miRs is associated with these eight biological capabilities acquired during GBM formation. Furthermore, we also discuss the applicable clinical potential of these research results. MiRs may aid in the diagnosis and prognosis of GBM. Moreover, miRs are also therapeutic targets of GBM. These studies will develop and improve precision medicine for GBM in the future.

Molecular mechanism of Notch signaling with special emphasis on microRNAs: Implications for glioma

Glioma is the most aggressive primary brain tumor and is notorious for resistance to chemoradiotherapy. Although its associated mechanisms are still not completely understood, Notch signaling, an evolutionarily conserved pathway, appears to be the key processes involved. Nevertheless, its mechanisms are sophisticated, due to a variety of targets and signal pathways, especially microRNA. MicroRNAs, which are small noncoding regulatory RNA molecules, have been proposed as one of the key mechanisms in glioma pathogenesis. Among the known glioma associated microRNA, microRNA-129, microRNA-34 family, and microRNA-326 have been shown to influence the progress of glioma through Notch signaling. Evidence also indicates that recurrence is due to development or persistence of the glioma stem-like cells and active angiogenesis, which are tightly regulated by a variety of factors, including Notch signaling. In this review, we summarize the recent progress regarding the functional roles of Notch signaling in glioma, including Notch ligand, microRNA, intracellular crosstalk, glioma stem-like cells and active angiogenesis and explore their clinical implications as diagnostic or prognostic biomarkers and molecular therapeutic targets for glioma.

Natural products: a hope for glioblastoma patients

Glioblastoma (GBM) is one of the most aggressive malignant tumors with an overall dismal survival averaging one year despite multimodality therapeutic interventions including surgery, radiotherapy and concomitant and adjuvant chemotherapy. Few drugs are FDA approved for GBM, and the addition of temozolomide (TMZ) to standard therapy increases the median survival by only 2.5 months. Targeted therapy appeared promising in in vitro monolayer cultures, but disappointed in preclinical and clinical trials, partly due to the poor penetration of drugs through the blood brain barrier (BBB). Cancer stem cells (CSCs) have intrinsic resistance to initial chemoradiation therapy (CRT) and acquire further resistance via deregulation of many signaling pathways. Due to the failure of classical chemotherapies and targeted drugs, research efforts focusing on the use of less toxic agents have increased. Interestingly, multiple natural compounds have shown antitumor and apoptotic effects in TMZ resistant and p53 mutant GBM cell lines and also displayed synergistic effects with TMZ. In this review, we have summarized the current literature on natural products or product analogs used to modulate the BBB permeability, induce cell death, eradicate CSCs and sensitize GBM to CRT.

ETV2 mediates endothelial transdifferentiation of glioblastoma

Glioblastoma multiforme (GBM) is characterized by extensive endothelial hyperplasia. Recent studies suggest that a subpopulation of endothelial cells originates via vasculogenesis by the transdifferentiation of GBM tumor cells into endothelial cells (endo-transdifferentiation). The molecular mechanism underlying this process remains poorly defined. Here, we show that the expression of ETS variant 2 (ETV2), a master regulator of endothelial cell development, is highly correlated with malignancy. Functional studies demonstrate that ETV2 is sufficient and necessary for the transdifferentiation of a subpopulation of CD133+/Nestin+ GBM/neural stem cells to an endothelial lineage. Combinational studies of ChIP-Seq with gain-of-function RNA-Seq data sets suggest that ETV2, in addition to activating vascular genes, represses proneural genes to direct endo-transdifferentiation. Since endo-transdifferentiation by ETV2 is VEGF-A independent, it likely accounts for the observed resistance of GBM tumor cells to anti-angiogenesis therapy. Further characterization of the regulatory networks mediated by ETV2 in endo-transdifferentiation of GBM tumor cells should lead to the identification of more effective therapeutic targets for GBM.

Notch1 is a prognostic factor that is distinctly activated in the classical and proneural subtype of glioblastoma and that promotes glioma cell survival via the NF-κB(p65) pathway

Glioblastomas (GBMs) are the most prevalent and devastating primary intracranial malignancies and have extensive heterogeneity. Notch1 signaling is a more complex process in the development of numerous cell and tissue types, including gliomagenesis and progression, and is upregulated in glioma-initiating cells. However, the contradictory expression of Notch1 among lower grade gliomas and GBMs confounds our understanding of GBM biology and has made identifying effective therapies difficult. In this study, we validated that Notch1 and NF-κB(p65) are highly expressed in the classical and proneural subtypes of GBM using the data set from The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA). DAPT and shRNA targeting Notch1 decreased NF-κB(p65) expression, suppressed cell proliferation, and induced apoptosis of GBM cells in vitro and in vivo. Furthermore, we illustrated that the intracellular Notch could bind with NF-κB(p65) in GBM cells. These findings suggest that the cross-talk between Notch1 signaling and NF-κB(p65) could contribute to the proliferation and apoptosis of glioma, and this discovery could help drive the design of more effective therapies in Notch1-targeted clinical trials.

Notch signaling: its roles and therapeutic potential in hematological malignancies

Notch is a highly conserved signaling system that allows neighboring cells to communicate, thereby controlling their differentiation, proliferation and apoptosis, with the outcome of its activation being highly dependent on signal strength and cell type. As such, there is growing evidence that disturbances in physiological Notch signaling contribute to cancer development and growth through various mechanisms. Notch was first reported to contribute to tumorigenesis in the early 90s, through identification of the involvement of the Notch1 gene in the chromosomal translocation t(7;9)(q34;q34.3), found in a small subset of T-cell acute lymphoblastic leukemia. Since then, Notch mutations and aberrant Notch signaling have been reported in numerous other precursor and mature hematological malignancies, of both myeloid and lymphoid origin, as well as many epithelial tumor types. Of note, Notch has been reported to have both oncogenic and tumor suppressor roles, dependent on the cancer cell type. In this review, we will first give a general description of the Notch signaling pathway, and its physiologic role in hematopoiesis. Next, we will review the role of aberrant Notch signaling in several hematological malignancies. Finally, we will discuss current and potential future therapeutic approaches targeting this pathway.

NOTCH blockade combined with radiation therapy and temozolomide prolongs survival of orthotopic glioblastoma

Glioblastoma multiforme (GBM) is the most common malignant brain tumor in adults. The current standard of care includes surgery followed by radiotherapy (RT) and chemotherapy with temozolomide (TMZ). Treatment often fails due to the radiation resistance and intrinsic or acquired TMZ resistance of a small percentage of cells with stem cell-like behavior (CSC). The NOTCH signaling pathway is expressed and active in human glioblastoma and NOTCH inhibitors attenuate tumor growth in vivo in xenograft models. Here we show using an image guided micro-CT and precision radiotherapy platform that a combination of the clinically approved NOTCH/γ-secretase inhibitor (GSI) RO4929097 with standard of care (TMZ + RT) reduces tumor growth and prolongs survival compared to dual combinations. We show that GSI in combination with RT and TMZ attenuates proliferation, decreases 3D spheroid growth and results into a marked reduction in clonogenic survival in primary and established glioma cell lines. We found that the glioma stem cell marker CD133, SOX2 and Nestin were reduced following combination treatments and NOTCH inhibitors albeit in a different manner. These findings indicate that NOTCH inhibition combined with standard of care treatment has an anti-glioma stem cell effect which provides an improved survival benefit for GBM and encourages further translational and clinical studies.

Cancer stem cells and signaling pathways in radioresistance

Radiation therapy (RT) is one of the most important strategies in cancer treatment. Radioresistance (the failure to RT) results in locoregional recurrence and metastasis. Therefore, it is critically important to investigate the mechanisms leading to cancer radioresistance to overcome this problem and increase patients' survival. Currently, the majority of the radioresistance-associated researches have focused on preclinical studies. Although the exact mechanisms of cancer radioresistance have not been fully uncovered, accumulating evidence supports that cancer stem cells (CSCs) and different signaling pathways play important roles in regulating radiation response and radioresistance. Therefore, targeting CSCs or signaling pathway proteins may hold promise for developing novel combination modalities and overcoming radioresistance. The present review focuses on the key evidence of CSC markers and several important signaling pathways in cancer radioresistance and explores innovative approaches for future radiation treatment.

Notch1 ablation radiosensitizes glioblastoma cells

Broad specific Notch1 inhibitors suppress glioblastoma multiforme (GBM) growth but have significant gastrointestinal toxicities. Here, we examined Notch1 expression in GBM tissue specimens and its correlation with the overall survival (OS) of GBM patients. Furthermore, using the CRISPR/Cas9 system, we investigated the effects of Notch1 downregulation on clonogenic growth and angiogenesis of GBM cells and xenografts. Immunohistochemistry showed positive Notch1 expression in 71% (49/69) of GBM tissues. Our multivariate Cox regression analysis further revealed that Notch1 expression was an independent adverse prognostic factor for OS. Notch1 downregulation suppressed the growth of GBM cells U87MG and U251. The mean duration to reach 6 x the starting volume was 18.3 days for xenografts with Notch1 downregulation and 13.4 days for the control xenografts. Immunofluorescent staining further disclosed that Notch1 downregulation markedly increased the number of γH2AX foci and radiosensitized GBM cells. Notch1 downregulation also impaired angiogenesis and attenuated VEGF and hypoxic response to irradiation in xenografts. In conclusion, Notch1 ablation inhibited GBM cell proliferation and neovascularization and radiosensitized GBM cells and xenografts, suggesting a pivotal role of Notch1 in tumor growth, angiogenesis, and radioresistance in GBM.

RNAi for contactin 2 inhibits proliferation of U87-glioma stem cells by downregulating AICD, EGFR, and HES1

Glioblastoma is the most common form of malignant brain tumors and has a poor prognosis. Glioma stem cells (GSCs) are thought to be responsible for the aberrant proliferation and invasion. Targeting the signaling pathways that promote proliferation in GSCs is one of the strategies for glioma treatment. In this study, we found increased expression of contactin 2 (CNTN2) and amyloid β precursor protein (APP) in U87-derived GSCs (U87-GSCs). RNA interference (RNAi) for CNTN2 downregulated the expression of APP intracellular domain (AICD), which is the proteolytic product of APP. Treatment with CNTN2 RNAi inhibited the proliferation of U87-GSCs. CNTN2 RNAi decreased the expression of epidermal growth factor receptor and HES1, which are potential targets of AICD. In summary, inhibition of the CNTN2/APP signaling pathway may repress the proliferation in U87-GSCs via downregulating the expression of HES1 and epidermal growth factor receptor. CNTN2/APP/AICD signaling pathway plays an important role in U87 glial tumorigenesis. Further studies are warranted to elucidate the role of these signaling pathways in other sources of GSCs. Depending on their role in proliferation in other sources of GSCs, members of the CNTN2/APP/AICD signaling pathway may provide novel targets for the development of therapy for glioblastomas.

Glioblastoma Stem-Like Cells: Characteristics, Microenvironment, and Therapy

Glioblastoma multiforme (GBM), grade IV astrocytoma, is the most fatal malignant primary brain tumor. GBM contains functional subsets of cells called glioblastoma stem-like cells (GSCs), which are radioresistant and chemoresistant and eventually lead to tumor recurrence. Recent studies showed that GSCs reside in particular tumor niches that are necessary to support their behavior. To successfully eradicate GBM growth and recurrence, new strategies selectively targeting GSCs and/or their microenvironmental niche should be designed. In this regard, here we focus on elucidating the molecular mechanisms that govern these GSC properties and on understanding the mechanism of the microenvironmental signals within the tumor mass. Moreover, to overcome the blood–brain barrier, which represents a critical limitation of GBM treatments, a new drug delivery system should be developed. Nanoparticles can be easily modified by different methods to facilitate delivery efficiency of chemotherapeutics, to enhance the accumulation within the tumors, and to promote the capacity for targeting the GSCs. Therefore, nanotechnology has become the most promising approach to GSC-targeting therapy. Additionally, we discussed the future of nanotechnology-based targeted therapy and point out the disadvantages that should be overcome.

Phase I study of RO4929097 with bevacizumab in patients with recurrent malignant glioma

Antiangiogenic therapies for malignant gliomas often result in transient response, and recurrent disease is characterized by adoption of invasive and hypoxic phenotype. The notch signaling pathway is activated in gliomas, and augments cell migration and hypoxic response. Here we report a clinical study of the combination of bevacizumab and RO4929097, an inhibitor of the notch signaling cascade. A phase I clinical trial was conducted through the Adult Brain Tumor Consortium in subjects with recurrent malignant glioma. Primary objectives were to assess safety and to define the maximum tolerated dose of RO4929097 in combination with bevacizumab. Secondary objectives were to determine overall survival, progression free survival, radiographic response, pharmacokinetic evaluation, and tissue biomarker analysis. Thirteen subjects were enrolled. Of the three subjects treated with the highest dose of RO4929097, one grade 3 toxicity and one grade 2 toxicity were observed. Definitive maximum tolerated dose of RO4929097 in combination with bevacizumab was not identified due to manufacturer's decision to halt drug production. 2 of 12 evaluable subjects demonstrated radiographic response; one subject experienced CR and the second PR. The median overall survival was 10.9 months with a median progression-free survival of 3.7 months. Two subjects remained free of disease progression at 6 months from treatment initiation. PK evaluation did not identify clinically significant drug-drug interactions. All analyzed tissue specimens revealed activation of notch signaling. Combination of RO4929097 and bevacizumab was well-tolerated. Given the compelling scientific rationale, additional studies of antiangiogenic and notch signaling inhibitors should be considered.

Molecular heterogeneity of glioblastomas: does location matter?

Glioblastomas in adults are highly heterogeneous tumors that can develop throughout the brain. To date no predictive-location marker has been identified. We previously derived two glioblastoma cell lines from cortical and periventricular locations and demonstrated distinct transcriptomic profiles. Based on these preliminary results, the aim of this study was to correlate glioblastoma locations with the expression of ten selected genes (VEGFC, FLT4, MET, HGF, CHI3L1, PROM1, NOTCH1, DLL3, PDGFRA, BCAN). Fifty nine patients with newly diagnosed glioblastomas were retrospectively included. Tumors were classified into cortical and periventricular locations, which were subsequently segregated according to cerebral lobes involved: cortical fronto-parietal (C-FP), cortical temporal (C-T), periventricular fronto-parietal (PV-FP), periventricular temporal (PV-T), and periventricular occipital (PV-O). Gene expression levels were determined using RT-qPCR. Compared to cortical glioblastomas, periventricular glioblastomas were characterized by a higher expression of two mesenchymal genes, VEGFC (p = 0.001) and HGF (p = 0.001). Among cortical locations, gene expressions were homogeneous. In contrast, periventricular locations exhibited distinct expression profiles. PV-T tumors were associated with higher expression of two proneural and cancer stem cell genes, NOTCH1 (p = 0.028) and PROM1 (p = 0.033) while PV-FP tumors were characterized by high expression of a mesenchymal gene, CHI3L1 (p = 0.006). Protein expression of NOTCH1 was correlated with RNA expression levels. PV-O glioblastomas were associated with lower expression of VEGFC (p = 0.032) than other periventricular locations, whereas MET overexpression remained exceptional. These data suggest a differential gene expression profile according to initial glioblastoma location.

Glioblastoma multiforme: Effect of hypoxia and hypoxia inducible factors on therapeutic approaches

Central nervous system-based cancers have a much higher mortality rate with the 2016 estimates at 6.4 for incidence and 4.3 for deaths per 100,000 individuals. Grade IV astrocytomas, known as glioblastomas are highly aggressive and show a high proliferation index, diffused infiltration, angiogenesis, microvascular proliferation and pleomorphic vessels, resistance to apoptosis, and pseudopalisading necrosis. Extensive hypoxic regions in glioblastomas contribute to the highly malignant phenotype of these tumors. Hypoxic regions of glioblastoma exacerbate the prognosis and clinical outcomes of the patients as hypoxic tumor cells are resistant to chemo- and radiation therapy and are also protected by the malfunctional vasculature that developed due to hypoxia. Predominantly, hypoxia-inducible factor-1α, vascular endothelial growth factor (VEGF)/VEGF receptor, transforming growth factor-β, epidermal growth factor receptor and PI3 kinase/Akt signaling systems are involved in tumor progression and growth. Glioblastomas are predominantly glycolytic and hypoxia-induced factors are useful in the metabolic reprogramming of these tumors. Abnormal vessel formation is crucial in generating pseudopalisading necrosis regions that protect cancer stem cells residing in that region from therapeutic agents and this facilitates the cancer stem cell niche to expand and contribute to cell proliferation and tumor growth. Therapeutic approaches that target hypoxia-induced factors, such as use of the monoclonal antibody against VEGF, bevacizumab, have been useful only in stabilizing the disease but failed to increase overall survival. Hypoxia-activated TH-302, a nitroimidazole prodrug of cytotoxin bromo-isophosphoramide mustard, appears to be more attractive due to its better beneficial effects in glioblastoma patients. A better understanding of the hypoxia-mediated protection of glioblastoma cells is required for developing more effective therapeutics.

Decreased miRNA-146A in Glioblastoma Multiforme and Regulation of Cell Proliferation and Apoptosis by Target Notch1

Objective

The primary purpose of this paper is to investigate the relationship between the microRNA 146a (miR-146a) and the proliferation of cells occurring in glioblastoma multiforme. The secondary purpose of the paper is to investigate abnormalities of expression in miR-146a.

Methods

A real-time PCR assay was used to investigate the abnormal expression of miR-146a in glioma and adjacent tissue. Lipofection was used to transfect a mimic of miR-146a and induce the upregulation of miR-146a. Real-time PCR was used to observe the expression level of miR-146a. A cell viability analysis was conducted using MTT. A luciferase report vector was used to identify potential targets for miR-146a.

Results

The miR-146a component was found to be downregulated in glioma tissue compared with adjacent nontumor tissue (p<0.05). The upregulation of miR-146a in glioma cells through miR-146a mimic transfection led to reduction of cell viability and to an increase in the percentage of apoptosis. Notch1 was the name of the potential targeted gene for miR-146a in glioma.

Conclusions

The study found that the presence of miR-146a potentially affected the proliferation of glioma cells by regulating the rate of Notch1 expression.