Development Of Glioblastoma Multiforme Research Articles

Identification of aberrantly methylated differentially expressed genes in glioblastoma multiforme and their association with patient survival.

Glioblastoma multiforme (GBM) is the most malignant primary tumour type of the central nervous system with limited therapeutic options and poor prognosis, and its pathogenic mechanisms have remained to be fully elucidated. Aberrant DNA methylation is involved in multiple biological processes and may contribute to the occurrence and development of GBM by affecting the expression of certain genes. However, the specific molecular mechanisms remain to be fully elucidated. The present study focused on uncovering differentially expressed genes with altered methylation status in GBM and aimed to discover novel biomarkers for the diagnosis and treatment of GBM. These genes were identified by combined analysis of multiple gene expression and methylation datasets from gene expression omnibus (GSE16011, GSE50161 and GSE 50923) to increase the reliability. In addition, The Cancer Genome Atlas (TCGA) dataset for GBM was used to test the stability of the results. Overall, 251 hypomethylated upregulated genes (Hypo-UGs) and 199 hypermethylated downregulated genes (Hyper-DGs) were identified in the present study. Functional enrichment analysis revealed that the Hypo-UGs are involved in the regulation of immune- and infection-associated signalling, while the Hyper-DGs are involved in the regulation of synaptic transmission. The three hub genes for Hyper-DGs (somatostatin, neuropeptide Y and adenylate cyclase 2) and five hub genes for Hypo-UGs [interleukin-8, matrix metalloproteinase (MMP)9, cyclin-dependent kinase 1, 2′-5′-oligoadenylate synthetase 1, C-X-C motif chemokine ligand 10 and MMP2] were identified by protein-protein interaction network analysis. Among the Hypo-UGs and Hyper-DGs, overexpression of C-type lectin domain containing 5A, epithelial membrane protein 3, solute carrier family 43 member 3, STEAP3 metalloreductase, tumour necrosis factor α-induced protein 6 and apolipoprotein B mRNA editing enzyme catalytic subunit 3G was significantly associated with poor prognosis in the TCGA and GSE16011 datasets (P<0.001). In conclusion, the present study uncovered numerous novel aberrantly methylated genes and pathways associated with GBM. Methylation-based markers, including the hub genes and prognostic genes identified, may potentially serve as markers for the diagnosis of GBM and targets for its treatment.

The analysis of miRNA expression profiling datasets reveals inverse microRNA patterns in glioblastoma and Alzheimer's disease.

There is recent evidence to indicate the existence of an inverse association between the incidence of neurological disorders and cancer development. Concurrently, the transcriptional pathways responsible for the onset of glioblastoma multiforme (GBM) and Alzheimer's disease (AD) have been found to be mutually exclusive between the two pathologies. Despite advancements being made concerning the knowledge of the molecular mechanisms responsible for the development of GBM and AD, little is known about the identity of the microRNA (miRNAs or miRs) involved in the development and progression of these two pathologies and their possible inverse expression patterns. On these bases, the aim of the present study was to identify a set of miRNAs significantly de-regulated in both GBM and AD, and hence to determine whether the identified miRNAs exhibit an inverse association within the two pathologies. For this purpose, miRNA expression profiling datasets derived from the Gene Expression Omnibus (GEO) DataSets and relative to GBM and AD were used. Once the miRNAs significantly de-regulated in both pathologies were identified, DIANA-mirPath pathway prediction and STRING Gene Ontology enrichment analyses were performed to establish their functional roles in each of the pathologies. The results allowed the identification of a set of miRNAs found de-regulated in both GBM and AD, whose expression levels were inversely associated in the two pathologies. In particular, a strong negative association was observed between the expression levels of miRNAs in GBM compared to AD, suggesting that although the molecular pathways behind the development of these two pathologies are the same, they appear to be inversely regulated by miRNAs. Despite the identification of this set of miRNAs which may be used for diagnostic, prognostic and therapeutic purposes, further functional in vitro and in vivo evaluations are warranted in order to validate the diagnostic and therapeutic potential of the identified miRNAs, as well as their involvement in the development of GBM and AD.

Analysis of microarray data for identification of key microRNA signatures in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is one of the most malignant types of glioma known for its reduced survival rate and rapid relapse. Previous studies have shown that the expression patterns of different microRNAs (miRNA/miR) play a crucial role in the development and progression of GBM. In order to identify potential miRNA signatures of GBM for prognostic and therapeutic purposes, we downloaded and analyzed two expression data sets from Gene Expression Omnibus profiling miRNA patterns of GBM compared with normal brain tissues. Validated targets of the deregulated miRNAs were identified using MirTarBase, and were mapped to Search Tool for the Retrieval of Interacting Genes/Proteins, Database for Annotation, Visualization and Integrated Discovery and Kyoto Encyclopedia of Genes and Genomes databases in order to construct interaction networks and identify enriched pathways of target genes. A total of 6 miRNAs were found to be deregulated in both expression datasets studied. Pathway analysis demonstrated that most of the target genes were enriched in signaling cascades connected to cancer development, such as ‘Pathways in cancer’, ‘Focal adhesion’ and ‘PI3K-Akt signaling pathway’. Of the five target genes that were enriched in the glioblastoma pathway, in the WikiPathway database, both HRas proto-oncogene, GTPase and MET proto-oncogene, receptor tyrosine kinase target genes of hsa-miR-139-5p, were found to be significantly associated with patient survival. The present study may thus form the basis for further exploration of hsa-miR-139-5p, not only as a therapeutic agent, but also as a diagnostic biomarker for GBM as well as a predictive marker for patient survival.

Epithelial membrane protein 1 promotes glioblastoma progression through the PI3K/AKT/mTOR signaling pathway

Glioblastoma multiforme (GBM) is the most malignant intracranial tumor. Although the affected patients are usually treated with surgery combined with radiotherapy and chemotherapy, the median survival time for GBM patients is still approximately 12–14 months. Identifying the key molecular mechanisms and targets of GBM development may therefore lead to the development of improved therapies for GBM patients. In the present study, the clinical significance and potential function of epithelial membrane protein 1 (EMP1) in malignant gliomas were investigated. Increased EMP1 expression was associated with increasing tumor grade (P<0.001) and worse prognosis in patients (P<0.001) based on TCGA, Rembrandt and CGGA databases for human gliomas. In vitro, gene silencing of EMP1 in U87MG and P3 GBM (primary glioma) cells significantly inhibited tumor proliferation and invasion. In addition, it was revealed that activation of the PI3K/AKT/mTOR signaling pathway is the driving force of EMP1-promoted glioma progression. Finally, it was demonstrated, using an intracranial GBM animal model, that EMP1 knockdown significantly inhibits tumor growth in vivo and increases overall survival in tumor-bearing animals. Our research provides new insights into the molecular mechanisms underlying EMP1 knockdown-mediated inhibition of GBM cell invasion and raises the possibility that targeting of EMP1 may represent a promising strategy for the treatment of GBM.

Phytanoyl-CoA 2-Hydroxylase-Interacting Protein-Like Gene Is a Therapeutic Target Gene for Glioblastoma Multiforme.

Glioblastoma multiforme (GBM) is the most common primary CNS cancer and has a poor prognosis. This study searched for significant genes and the mechanisms involved in GBM.We used the Gene Expression Omnibus (GEO) to test the WHO normal and IV glioma database, used R tool to identify the significant gene, and finally, combined these with The Cancer Genome Atlas (TCGA) to verify the significant genes. Subsequently, we explored the biological mechanisms involved.Phytanoyl-CoA 2-hydroxylase-interacting protein-like gene (PHYHIPL) is downregulated in grade IV glioma (GBM). The downregulation of PHYHIPL in GBM is accompanied by poor overall survival in the TCGA database, which indicates that PHYHIPL is a protection gene in GBM development. Bioinformatics analysis shows that the poor prognosis with downregulated PHYHIPL may be the result of the TNF signaling pathway and the IL-17 signaling pathway, but good prognosis accompanied by upregulated PHYHIPL may be the result of retrograde endocannabinoid signaling and the cAMP signaling pathway. Protein-protein interactions (PPI) net indicated that PHYHIPL may play a vital role in cell metabolism, and we hypothesize that the downregulation mechanism may be the result of mutations of the β-catenin gene and the endogenous siRNA, as shown in previous studies.PHYHIPL may be a target gene for the treatment and prognosis of GBM.

Comparison and analysis of lncRNA-mediated ceRNA regulation in different molecular subtypes of glioblastoma.

Glioblastoma multiforme (GBM) is the most malignant brain tumor with a poor prognosis. A molecular level classification of GBM can provide insight into accurate patient-specific treatment. Competitive endogenous RNAs (ceRNAs), such as long non-coding RNAs (lncRNAs), play an essential role in the development of tumors and are associated with survival. However, the pattern of lncRNA-mediated ceRNA (LMce) crosstalk in different GBM subtypes is still unclear. In this study, we present a computational cascade to construct LMce networks of different GBM subtypes and investigate the lncRNA-mRNA regulations among them. Our results showed that although most lncRNAs and mRNAs in the different GBM subtype networks were the same, the regulation relationships of these RNAs were different among subtypes. 42.5%, 50.9%, 43.5% and 65.0% lncRNA-mRNA regulatory pairs were classic (CL)-, mesenchymal (MES)-, proneural (PN)- and neural (NE)-specific. In addition, our study identified 61, 132, 24 and 16 modules in which lncRNAs and mRNAs synergically competed with each other for miRNAs as CL-, MES-, PN- and NE-specific. CL- and MES-specific modules were mainly involved in biological functions such as cell proliferation, apoptosis and migration, while PN- and NE-specific modules were mainly related to DNA damage and cell cycle dysregulation. Survival analysis demonstrated that some modules could be potential prognostic markers of patients of CL and MES subtypes. This study uncovered the LMce interaction patterns in different GBM subtypes, identified subtype-specific modules with distinct biological functions, and revealed the potential prognostic markers of patients of different GBM subtypes. These results might contribute to the discovery of the GBM prognostic biomarkers and development of a more accurate therapeutic process.

The RNA helicase DHX33 is required for cancer cell proliferation in human glioblastoma and confers resistance to PI3K/mTOR inhibition

Human Glioblastoma is one deadly disease; the median survival time is reported to be 13.9 months after treatment. In the present study, we discovered that DHX33 is highly expressed in 84% of all Glioblastoma multiforme (GBM). Knockdown of DHX33 led to significant reduced proliferation and migration in glioblastoma cells in vitro and in vivo. Mechanistically, DHX33 regulated a set of critical genes involved in cell cycle and cell migration to promote glioblastoma development. Additionally, DHX33 was found to be induced by inhibitors of PI3K and mTOR whose activation has been detected in 50% of glioblastoma. Overexpression of wild type DHX33 protein, but not the helicase dead mutant, confers resistance to mTOR inhibitors in glioblastoma cells. DHX33 probably functions as a critical regulator to promote GBM development. Our results highlight its therapeutic potential in treating GBM.

Investigating the role of CRIPTO-1 (TDGF-1) in glioblastoma multiforme U87 cell line.

Cripto-1 has been implicated in a number of human cancers. Although there is high potential for a role of Cripto-1 in glioblastoma multiforme (GBM) pathogenesis and progression, few studies have tried to define its role in GBM. These studies were limited in that Cripto-1 expression was not studied in detail in relation to markers of cancer initiation and progression. Therefore, these correlative studies allowed limited interpretation of Criptos-1's effect on the various aspects of GBM development using the U87 GBM cell line. In this study, we sought to delineate the role of Cripto-1 in facilitating pathogenesis, stemness, proliferation, invasion, migration and angiogenesis in GBM. Our findings show that upon overexpressing Cripto-1 in U87 GBM cells, the stemness markers Nanog, Oct4, Sox2, and CD44 increased expression. Similarly, an increase in Ki67 was observed demonstrating Cripto-1's potential to induce cellular proliferation. Likewise, we report a novel finding that increased expression of the markers of migration and invasion, Vimentin and Twist, correlated with upregulation of Cripto-1. Moreover, Cripto-1 exposure led to VEGFR-2 overexpression along with higher tube formation under conditions promoting endothelial growth. Taken together our results support a role for Cripto-1 in the initiation, development, progression, and maintenance of GBM pathogenesis. The data presented here are also consistent with a role for Cripto-1 in the re-growth and invasive growth in GBM. This highlights its potential use as a predictive and diagnostic marker in GBM as well as a therapeutic target.

Impact of gender on the survival of patients with glioblastoma.

Background: Preclinical models have suggested a role for sex hormones in the development of glioblastoma multiforme (GBM). However, the impact of gender on the survival time of patients with GBM has not been fully understood. The objective of the present study was to clarify the association between gender and survival of patients with GBM by analyzing population-based data.Methods: We searched the Surveillance, Epidemiology, and End-Results database who were diagnosed with GBM between 2000 and 2008 and were treated with surgery. Five-year cancer specific survival data were obtained. Kaplan–Meier methods and multivariable Cox regression models were used to analyze long-term survival outcomes and risk factors.Results: A total of 6586 patients were identified; 61.5% were men and 38.5% were women. The 5-year cancer-specific survival (CSS) rates in the male and female groups were 6.8% and 8.3%, respectively (P=0.002 by univariate and P<0.001 by multivariate analysis). A stratified analysis showed that male patients always had the lowest CSS rate across localized cancer stage and different age subgroups.Conclusions: Gender has prognostic value for determining GBM risk. The role of sex hormones in the development of GBM warrants further investigation.

MicroRNA‑876‑5p inhibits the progression of glioblastoma multiforme by directly targeting Forkhead boxM1.

Considerable evidence has suggested that microRNAs (miRNAs) are dysregulated in glioblastoma multiforme (GBM), and their dysregulation may modulate the aggressiveness of GBM. Therefore, miRNAs with dysregulated expression are potential therapeutic targets for the treatment of GBM. miRNA‑876‑5p (miR‑876‑5p) has recently been identified to be aberrantly expressed and serve an important role in hepatocellular carcinoma and lung cancer. However, its expression pattern and functional significance in GBM remains largely unknown. Therefore, the present study detected miR‑876‑5p expression in GBM, examined the biological roles of miR‑876‑5p in GBM progression and explored its underlying mechanism. The present study demonstrated that miR‑876‑5p expression was significantly downregulated in GBM tissues and cell lines. Overexpression of miR‑876‑5p restricted the proliferation, induced the apoptosis and reduced the migration and invasion capabilities of GBM cells. In GBM cells, Forkhead boxM1 (FOXM1) was identified as a direct target of miR‑876‑5p. FOXM1 was overexpressed in clinical GBM tissues, and its overexpression was inversely correlated with miR‑876‑5p level. Small interfering RNA‑mediated knockdown of FOXM1 exhibited effects similar to those of miR‑876‑5p overexpression in GBM cells. The tumour suppressive roles of miR‑876‑5p overexpression in GBM cells were significantly reversed by FOXM1 reintroduction. Overall, the present results revealed that miR‑876‑5p may inhibit the development of GBM by directly targeting FOXM1, suggesting that this miRNA may be a potential therapeutic target in patients, for the management of GBM.

Chemo-resistance of A172 glioblastoma cells is controlled by miR-1271-regulated Bcl-2.

MicroRNAs (miRNAs) have been reported to exert important effects on the initiation, progression and metastasis of glioblastoma multiforme (GBM). In this study, we aimed to explore the regulation role of miR-1271 on the development of GBM. We found that miR-1271 was a Bcl-2-targeting miRNA, and the levels of miR-1271was decreased in samples from patients with GBM, compared with those from corresponding normal tissue samples. On the other hand, the levels of miR-1271 were inversely related to the levels of Bcl-2, which have been significantly increased in GBM samples. The overall survival was poorer in patients with low levels of miR-1271, compared to those with high levels of miR-1271. In vitro, the chemo-resistant cell survival mediated with Bcl-2 was inhibited by overexpression of miR-1271 and was enhanced by depletion of miR-1271. Thus, the chemo-resistance of GBM cells may be promoted after suppressing miR-1271 through cell survival mediated with Bcl-2. The prognosis of patients with GBM receiving chemotherapy may be improved by overexpressing miR-1271 in cancerous cells.

Integration of gene interaction information into a reweighted random survival forest approach for accurate survival prediction and survival biomarker discovery

Accurately predicting patient risk and identifying survival biomarkers are two important tasks in survival analysis. For the emerging high-throughput gene expression data, random survival forest (RSF) is attracting more and more attention as it not only shows excellent performance on survival prediction problems with high-dimensional variables, but also is capable of identifying important variables according to variable importance automatically calculated within the algorithm. However, RSF still suffers from some problems such as limited predictive accuracy on independent datasets and limited biological interpretation of survival biomarkers. In this study, we integrated gene interaction information into a Reweighted RSF model (RRSF) to improve predictive accuracy and identify biologically meaningful survival markers. We applied RRSF to the prediction of patients with glioblastoma multiforme (GBM) and esophageal squamous cell carcinoma (ESCC). With a reconstructed global pathway network and an mRNA-lncRNA co-expression network as the prior gene interaction information, RRSF showed better overall predictive performance than RSF on three GBM and two ESCC datasets. In addition, RRSF identified a two-gene and three-lncRNA signature, which showed robust prognostic values and had high biological relevance to the development of GBM and ESCC, respectively.

The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma.

Glioblastoma multiforme (GBM) is the most common primary malignant tumor affecting the human brain. Despite improvements in therapeutic technologies, patients with GBM have a poor clinical result and the molecular mechanisms responsible for the development of GBM have not yet been fully elucidated. 3-phosphoinositide dependent protein kinase1 (PDK1) is upregulated in various tumors and promotes tumor invasion. In glioma, transforming growth factor-β (TGF‑β) promotes cell invasion; however, whether TGF‑β directly regulates PDK1 protein and promotes proliferation and invasion is not yet clear. In this study, PDK1 levels were measured in glioma tissues using tissue microarray (TMA) by immunohistochemistry (IHC) and RT‑qPCR. Kaplan-Meier analyses were used to calculate the survival rate of patients with glioma. In vitro, U251 and U87 glioma cell lines were used for functional analyses. Cell proliferation and invasion were analyzed using siRNA transfection, MTT assay, RT‑qPCR, western blot analysis, flow cytometry and invasion assay. Invivo, U251 glioma cell xenografts were established. The results revealed that PDK1 protein was significantly upregulated in glioma tissues compared with non-tumorous tissues. Furthermore, the higher PDK1 levels were associated with a large tumor size (>5.0cm), a higher WHO grade and a shorter survival of patients with GBM. Univariate and multivariate analyses indicated that PDK1 was an independent prognostic factor. Invivo, PDK1 promoted glioma tumor xenograft growth. Invitro, functional analyses confirmed that TGF‑β upregulated PDK1 protein expression and PDK1 promoted cell migration and invasion, and functioned as an oncogene in GBM, by upregulating c‑Jun protein and inducing epithelial-mesenchymal transition (EMT). c‑Jun protein were overexpressed in glioma tissues and positively correlated with PDK1 levels. Moreover, our findings were further validated by the online Oncomine database. On the whole, the findings of this study indicate that in GBM, PDK1 functions as an oncogene, promoting proliferation and invasion.

Depression and glioblastoma, complicated concomitant diseases: a systemic review of published literature

Glioblastoma multiforme (GBM) is the most common primary brain cancer. Depression is a common co-morbidity of this condition. Despite this common interaction, relatively little research has been performed on the development of GBM-associated depression. We performed a literary search of the PubMed database for articles published relating to GBM and depression. A total of 85 articles were identified with 46 meeting inclusion criteria. Depression significantly impacts care, decreasing medication compliance, and patient survival. Diagnostically, because depression and GBM share intricate neuro-connectivity in a way that effect functionality, these diseases can be mistaken for alternative psychological or pathological disorders, complicating care. Therapeutically, anti-depressants have anti-tumor properties; yet, some have been shown to interfere with GBM treatment. One reason for this is that the pathophysiological development of depression and GBM share several pathways including altered regulation of the 5-HT receptor, norepinephrine, and 3':5'-cyclic monophosphate. Over time, depression can persist after GBM treatment, affecting patient quality of life. Together, depression and GBM are complicated concomitant diseases. Clinicians must be aware of their co-existence. Because of overlapping molecular pathways involved in both diseases, careful medication selection is imperative to avoid potential adverse interactions. Since GBMs are the most common primary brain cancer, physicians dealing with this disease should be prepared for the development of depression as a potential sequela of this condition, given the related pathophysiology and the known poor outcomes.

Angiogenesis inhibition on glioblastoma multiforme cell lines (U-87 MG and T98G) by AT-101

Abstract Aim Glioblastoma multiforme (GBM) is the most common glial tumor. Angiogenesis which provides nutrient and oxygen support to proliferating cells play an essential role in GBM development, proliferation and metastasis. The development of antiangiogenetic agents is a promising treatment issue as blood vessels are essential for the vitality of tumor cells. AT-101 is -(−) enantiomer of gossypol having anti-proliferative effects on different cancer cell lines. In this study, the cytotoxicity effect of AT-101 on GBM cell lines (U-87MG ve T98G) was confirmed and also the impact of this drug on VEGF synthesis on these cell lines were evaluated at transcriptional and protein levels. Materials and methods U-87 MG and T98 cell lines were treated with increasing concentrations (1–50 μM) of AT-101 for 72 h. Cytotoxicity was determined by xCELLigence (Roche). Apoptosis was detected by using ELISA and confirmed by caspase assay. VEGF and other proangiogenic factors expression were evaluated by angiogenesis array. Results The cell vitality was constantly followed up in the experiment. The cytotoxicity of AT-101 in both cell lines increased significantly at 24 h. The IC-50 values of U-87 MG and T98 were 2.4 and 2.7 μM respectively. The VEGF mRNA levels decreased by 2.7 fold in U-87MG and 3 fold in T98G by treating these cell lines with AT-101 IC50 dose for 24 h. Conclusions This study showed that AT-101 suppress VEGF on protein levels at U-87 MG and T98G cell lines and showed AT-101 might be a promising targeted agent in GBM treatment.

LAMP-1 gene is overexpressed in high grade glioma.

High-grade gliomas (HGG) are the most frequent brain tumors in adults. Glioblastoma multiforme (GBM) is their most aggressive form resistant to therapy. It was shown that inhibition ofautophagyreduced GBM development and autophagyinterfering agents are regarded as a new strategy to fight glioma cells. The lysosome-associated membrane proteins (LAMPs) display differential expression particularly in cancer. There are few data on their expression and especially on their molecular profile. The aim of the present study is to investigate the expression of LAMP-1 and LAMP-2 genes and proteins in HGG. Newly diagnosed patients with HGG and healthy controls were examined by immunohistochemistry and qPCR for both protein and mRNA levels of LAMP-1 and LAMP-2. The transcriptional activity of LAMP-1 in HGG was significantly higher compared to normal brain and to LAMP-2. The two glycoproteins were detected in the cytosol of tumor cells with varying intensity, LAMP-1 showing again enhanced expression. In conclusion, novel data on LAMP-1 overexpression in HGG are presented suggesting involvement of this gene and protein in cell adhesion and tumor progression. These findings might help the elucidation of the complex biological role of the multifunctional LAMPs proteins and to predict novel therapeutic targets in lysosomes.

Cancer stem cells from peritumoral tissue of glioblastoma multiforme: the possible missing link between tumor development and progression.

In glioblastoma multiforme (GBM), cancer stem cells (CSCs) are thought to be responsible for gliomagenesis, resistance to treatment and recurrence. Unfortunately, the prognosis for GBM remains poor and recurrence frequently occurs in the peritumoral tissue within 2 cm from the tumor edge. In this area, a population of CSCs has been demonstrated which may recapitulate the tumor after surgical resection. In the present study, we aimed to characterize CSCs derived from both peritumoral tissue (PCSCs) and GBM (GCSCs) in order to deepen their significance in GBM development and progression. The stemness of PCSC/GCSC pairs obtained from four human GBM surgical specimens was investigated by comparing the expression of specific stem cell markers such as Nestin, Musashi-1 and SOX2. In addition, the growth rate, the ultrastructural features and the expression of other molecules such as c-Met, pMet and MAP kinases, involved in cell migration/invasion, maintenance of tumor stemness and/or resistance to treatments were evaluated. Since it has been recently demonstrated the involvement of the long non-coding RNAs (lncRNAs) in the progression of gliomas, the expression of H19 lncRNA, as well as of one of its two mature products miR-675-5p was evaluated in neurospheres. Our results show significant differences between GCSCs and PCSCs in terms of proliferation, ultrastructural peculiarities and, at a lower extent, stemness profile. These differences might be important in view of their potential role as a therapeutic target.

An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective.

Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.

PD-L1 confers glioblastoma multiforme malignancy via Ras binding and Ras/Erk/EMT activation

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor due to the lack of effective therapeutic drugs. Cancer therapy targeting programmed cell death protein 1 (PD-1) or programmed death ligand-1 (PD-L1) is of revolutionary. However, the role of intrinsic PD-L1, which determines immune-therapy outcomes, remains largely unclear. Here we demonstrated an oncogenic role of PD-L1 via binding and activating Ras in GBM cells. RNA-sequencing transcriptome data revealed that PD-L1 significantly altered gene expression enriched in cell growth/migration/invasion pathways in human GBM cells. PD-L1 overexpression and knockout or knockdown demonstrated that PD-L1 promoted GBM cell proliferation and migration in vitro and in vivo. Mechanistically, PD-L1 prominently activated epithelial mesenchymal transition (EMT) process in a MEK/Erk- but not PI3K/Akt-dependent manner. Further, we identified intracellular interactions of PD-L1 and H-Ras, which led to Ras/Erk/EMT activation. Finally, we demonstrated that PD-L1 overexpression promoted while knockdown abolished GBM development and invasion in orthotopic GBM models of rodents. Taken together, we found that intracellular PD-L1 confers GBM cell malignancy and aggressiveness via binding Ras and activating the downstream Erk-EMT signaling. Thus, these results shed important insights in improving efficacy of immune therapy for GBM as well as other malignant tumors.

New extracellular factors in glioblastoma multiforme development: neurotensin, growth differentiation factor-15, sphingosine-1-phosphate and cytomegalovirus infection.

Recent years have seen considerable progress in understanding the biochemistry of cancer. For example, more significance is now assigned to the tumor microenvironment, especially with regard to intercellular signaling in the tumor niche which depends on many factors secreted by tumor cells. In addition, great progress has been made in understanding the influence of factors such as neurotensin, growth differentiation factor-15 (GDF-15), sphingosine-1-phosphate (S1P), and infection with cytomegalovirus (CMV) on the ‘hallmarks of cancer’ in glioblastoma multiforme.Therefore, in the present work we describe the influence of these factors on the proliferation and apoptosis of neoplastic cells, cancer stem cells, angiogenesis, migration and invasion, and cancer immune evasion in a glioblastoma multiforme tumor. In particular, we discuss the effect of neurotensin, GDF-15, S1P (including the drug FTY720), and infection with CMV on tumor-associated macrophages (TAM), microglial cells, neutrophil and regulatory T cells (Treg), on the tumor microenvironment. In order to better understand the role of the aforementioned factors in tumoral processes, we outline the latest models of intratumoral heterogeneity in glioblastoma multiforme. Based on the most recent reports, we discuss the problems of multi-drug therapy in treating glioblastoma multiforme.