Molecular markers in glioma

FAM225B Is a Prognostic lncRNA for Patients with Recurrent Glioblastoma

Objective

The overall survival of patients with recurrent glioblastoma (rGBM) is quite different, so clinical outcome prediction is necessary to guide personalized clinical treatment for patients with rGBM. The expression level of lncRNA FAM225B was analyzed to determine its prognostic value in rGBMs.

Methods

We collected 109 samples of Chinese Glioma Genome Atlas (CGGA) RNA sequencing dataset and divided into training set and validation set. Then, we analyzed the expression of FAM225B, clinical characteristics, and overall survival (OS) information. Kaplan-Meier survival analysis was used to estimate the OS distributions. The prognostic value of FAM225B in rGBMs was tested by univariate and multivariate Cox regression analyses. Moreover, we analyzed the biological processes and signaling pathways of FAM225B.

Results

We found that FAM225B was upregulated in rGBMs (P = 0.0009). The expression of FAM225B increased with the grades of gliomas (P < 0.0001). The OS of rGBMs in the low-expression group was significantly longer than that in the high-expression group (P = 0.0041). Similar result was found in the training set (P = 0.0340) and verified in the validation set (P = 0.0292). In multivariate Cox regression analysis, FAM225B was identified to be an independent prognostic factor for rGBMs (P = 0.003). Biological process and KEGG pathway analyses implied FAM225B mainly played a functional role on transcription, regulation of transcription, cell migration, focal adhesion, etc.

Conclusions

FAM225B is expected to be as a new prognostic biomarker for the identification of rGBM patients with poor outcome. And our study provided a potential therapeutic target for rGBMs.

Current biomarker-associated procedures of cancer modeling-a reference in the context of IDH1 mutant glioma

Isocitrate dehydrogenases (IDH1/2) are central molecular markers for glioblastoma. Providing in vitro or in vivo models with mutated IDH1/2 can help prepare facilities to understand the biology of these mutated genes as glioma markers, as well as help, improve therapeutic strategies. In this review, we first summarize the biology principles of IDH and its mutations and outline the core primary findings in the clinical context of neuro-oncology. Given the extensive research interest and exciting developments in current stem cell biology and genome editing, the central part of the manuscript is dedicated to introducing various routes of disease modeling strategies of IDH mutation (IDHMut) glioma and comparing the scientific-technological findings from the field using different engineering methods. Lastly, by giving our perspective on the benefits and limitations of patient-derived and donor-derived disease modeling respectively, we aim to propose leading research questions to be answered in the context of IDH1 and glioma.

Short tandem repeat profiling for the authentication of cancer stem-like cells

Colorectal and glioblastoma cancer stem‐like cells (CSCs) are essential for translational research. Cell line authentication by short tandem repeat (STR) profiling ensures reproducibility of results in oncology research. This technique enables to identify mislabeling or cross‐contamination of cell lines. In our study, we provide a reference dataset for a panel of colorectal and glioblastoma CSCs that allows authentication. Each cell line was entered into the cell Line Integrated Molecular Authentication database 2.1 to be compared to the STR profiles of 4485 tumor cell lines. This article also provides clinical data of patients from whom CSCs arose and data on the parent tumor stage and mutations. STR profiles and information of our CSCs are also available in the Cellosaurus database (ExPASy) as identified by unique research resource identifier codes.

Human cell lines obtained from cancer stem‐like cells represent an invaluable model for studying tumor properties. Cell line authentication by short tandem repeat (STR) profiling is an important tool to identify the potential mislabeling or cross‐contamination of cell lines. Here, the authors characterized 18 colorectal cancer stem‐like cell lines from 17 patients and 103 glioblastoma cancer stem‐like cell lines from 95 patients by STR profiling to create a reference dataset that allows the authentication of these cell lines and their identification through a unique research resource identifier. The results will help further ensure the reliability and reproducibility of research experiments.

IDH1-mutant primary intraventricular gliosarcoma: Case report and systematic review of a rare location and molecular profile

Background:

Gliosarcoma (GS) is classified as an IDH-wild-type variant of glioblastoma (GBM). While GS is already an unusual presentation of GBM, IDH1-mutant cases are especially rare. We present an IDH1-mutant primary intraventricular GS case report and a systematic review of the molecular profile in GS correlating to the prognostic and pathogenesis of IDH1/2 mutations.

Case Description:

A 44-years-old man presented with ongoing fatigue symptoms and a new-onset intense occipital headache. The patient complained of memory loss, dyscalculia, and concentration difficulties. An MRI revealed a bihemispheric intraventricular mass crossing the midline through the corpus callosum and infiltrating the trigone of the lateral ventricles, hypointense, and hyperintense on the T1- and T2-weighted image. We performed a microsurgical resection with a transparietal transsulcal approach; however, the contralateral mass was attached to vascular structures and we decided to reoperate the patient in another moment. The histopathological study showed a Grade IV tumor and the immunohistochemistry confirmed the diagnosis of GS. The patient presented progressive neurologic decline and died 45 days after the surgical approach.

Conclusion:

We did two systematic reviews studies from PubMed, EMBASE, MEDLINE, Cochrane, and SCOPUS databases, and included molecular and intraventricular studies of GS. We performed further meta-analysis using OpenMetaAnalyst™ software. We conducted a forest plot with the molecular profile of GS. When correlated IDH1 mutation versus tp53 mutation, we found an odds ratio (OR) of 0.018 (0.005–0.064) and P < 0.001. Moreover, we compared IDH1 mutation versus MGMT methylation (P = 0.006; OR = 0.138 [0.034–0.562]). The studies evaluating the molecular profile in GS prognostics are often extended from all GBMs despite specifics GBM variants (i.e., GS). We found a correlation between IDH1 mutation expression with tp53 and MGMT expression in GS, and future studies exploring this molecular profile in GS are strongly encouraged.

Long-term efficacy of surgical resection with or without adjuvant therapy for treatment of secondary glioblastoma in adults

Background

There are limited studies on treatment strategies and associated clinical outcomes in patients with secondary glioblastoma (sGBM). We sought to investigate the prognostic factors and treatment decisions in a retrospective cohort of patients with sGBM.

Methods

One hundred and seventy-one patients with sGBM who met the screening criteria were included in this study. Kaplan–Meier survival analysis and Cox survival analysis were used to detect prognostic factors. R (v3.5.0) and SPSS software (v25.0, IBM) were used to perform statistical analyses.

Results

The median overall survival was 303 days (range 23–2237 days) and the median progression-free survival was 229 days (range 33–1964 days) in patients with sGBM. When assessing the relationship between adjuvant treatment outcome and extent of resection (EOR), the results showed that patients underwent gross total resection can benefit from postoperative radiotherapy and chemotherapy, but not in patients underwent subtotal resection. In addition, we also found that aggressive adjuvant therapy can significantly improve clinical outcomes of IDH1-mutated patients but no significant prognostic value for IDH1-wildtyped patients. The univariate Cox regression analyses demonstrated that EOR, adjuvant therapy, and postoperative Karnofsky Performance Scores were prognostic factors for patients with sGBM, and multivariate COX analysis confirmed that adjuvant therapy and EOR were independent prognostic factors.

Conclusions

For patients with sGBM, aggressive postoperative adjuvant therapy after gross total resection was recommended. However, we did not detect a benefit in IDH1-wildtype patients in our cohort.

Identification and validation of potential novel prognostic biomarkers for patients with glioma based on a gene co-expression network

BACKGROUND

Glioma is widely regarded as one of most lethal and challenging diseases of the nervous system. The aim of this study was to identify novel biomarkers that offer better prognosis prediction for Chinese patients with glioma.

METHODS

By using systematic approaches, the co-expression modules were identified from the Chinese Glioma Genome Atlas (CGGA) database through weighted gene co-expression network analysis and functional enrichment of essential modules of Kyoto Encyclopedia of Genes and Genomes terms. The co-expression modules were validated using The Cancer Genome Atlas database and the protein-protein interaction (PPI) network.

RESULTS

For network construction, 5,374 among 21,494 genes were selected, and an increasing genetic variance was associated with the prognosis of glioma. By using functional enrichment analysis, the involvement of multiple vital processes, including metabolism of fatty acids, was correlated with the patient prognosis. Notably, five hub genes (KCNB1, UST, SOX8, KLHL42, and HDAC4) were identified for these processes. Accordingly, using the Kaplan-Meier method, there was enhanced expression of these genes in patients with significantly lower overall survival rates, especially those from the CGGA database.

CONCLUSIONS

This study not only revealed the essential co-expression gene modules in patients with glioma, but it also unraveled the potential signaling pathways underlying these functional processes.

Adenovirus infection promotes the formation of glioma stem cells from glioblastoma cells through the TLR9/NEAT1/STAT3 pathway

BACKGROUND

Glioma stem cells (GSCs) are glioma cells with stemness and are responsible for a variety of malignant behaviors of glioma. Evidence has shown that signals from tumor microenvironment (TME) enhance stemness of glioma cells. However, identification of the signaling molecules and underlying mechanisms has not been completely elucidated.

METHODS

Human samples and glioma cell lines were cultured in vitro to determine the effects of adenovirus (ADV) infection by sphere formation, RT-qPCR, western blotting, FACS and immunofluorescence. For in vivo analysis, mouse intracranial tumor model was applied. Bioinformatics analysis, gene knockdown by siRNA, RT-qPCR and western blotting were applied for further mechanistic studies.

RESULTS

Infection of patient-derived glioma cells with ADV increases the formation of tumor spheres. ADV infection upregulated stem cell markers and in turn promoted the capacities of self-renewal and multi-lineage differentiation of the infected tumor spheres. These ADV infected tumor spheres had stronger potential to form xenograft tumors in immune-compromised mice. GSCs formation could be promoted by ADV infection via TLR9, because TLR9 was upregulated after ADV infection, and knockdown of TLR9 reduced ADV-induced GSCs. Consistently, MYD88, as well as total STAT3 and phosphorylated (p-)STAT3, were also upregulated in ADV-induced GSCs. Knockdown of MYD88 or pharmaceutical inhibition of STAT3 attenuated stemness of ADV-induced GSCs. Moreover, we found that ADV infection upregulated lncRNA NEAT1. Knockdown of NEAT1 impaired stemness of ADV-induced GSCs. Lastly, HMGB1, a damage associated molecular pattern (DAMP) that triggers TLR signaling, also upregulated stemness markers in glioma cells.

CONCLUSION

ADV, which has been developed as vectors for gene therapy and oncolytic virus, promotes the formation of GSCs via TLR9/NEAT1/STAT3 signaling. Video abstract.

Human cord blood hematopoietic cells acquire neural features when cultured in the presence of neurogenic cytokines

In vitro growth of hematopoietic cells depends on the presence of hematopoietic cytokines. To date, it is unclear if these cells would be able to respond to non-hematopoietic cytokines. In the present study, we have explored this by culturing human hematopoietic cells in presence of neurogenic cytokines. Lineage-negative (Lin^-) umbilical cord blood (UCB)-derived cells -enriched for hematopoietic stem and progenitor cells- were cultured in presence of different combinations of hematopoietic cytokines, neurotrophins, epidermal growth factor, fibroblast growth factor, and neurogenic culture media, in a 3-phase culture system. A proportion (1-22%) of Lin^- UCB hematopoietic cells normally express neural markers and are capable of responding to neural cytokines. Neural cytokines did not have effects on hematopoietic cell proliferation; however, we observed generation of neural-like cells, assessed by morphology, and a significant increase in the proportion of cells expressing neural markers. Such neural-like cells, however, retained expression of hematopoietic markers. It seems that under our culture conditions, no actual transdifferentiation of hematopoietic cells into neural cells occurred; instead, the cells generated in culture seem to be hematopoietic cells that acquired neural features upon contact with neurogenic factors. The identity of UCB cells that acquired a neural phenotype is still unclear.

Therapeutic Strategies for Overcoming Immunotherapy Resistance Mediated by Immunosuppressive Factors of the Glioblastoma Microenvironment

Various mechanisms of treatment resistance have been reported for glioblastoma (GBM) and other tumors. Resistance to immunotherapy in GBM patients may be caused by acquisition of immunosuppressive ability by tumor cells and an altered tumor microenvironment. Although novel strategies using an immune-checkpoint inhibitor (ICI), such as anti-programmed cell death-1 antibody, have been clinically proven to be effective in many types of malignant tumors, such strategies may be insufficient to prevent regrowth in recurrent GBM. The main cause of GBM recurrence may be the existence of an immunosuppressive tumor microenvironment involving immunosuppressive cytokines, extracellular vesicles, chemokines produced by glioma and glioma-initiating cells, immunosuppressive cells, etc. Among these, recent research has paid attention to various immunosuppressive cells—including M2-type macrophages and myeloid-derived suppressor cells—that cause immunosuppression in GBM microenvironments. Here, we review the epidemiological features, tumor immune microenvironment, and associations between the expression of immune checkpoint molecules and the prognosis of GBM. We also reviewed various ongoing or future immunotherapies for GBM. Various strategies, such as a combination of ICI therapies, might overcome these immunosuppressive mechanisms in the GBM microenvironment.

Abnormal polarization of macrophage-like cells in the peripheral blood of patients with glioma

Glioma is a type of malignant tumor arising from glial cells of the brain or the spine. Circulation-derived macrophage infiltration is a characteristic of the glioma microenvironment. The polarization status of circulation-derived macrophages in patients with glioma remains unclear. Therefore, the present study aimed to evaluate the polarization status of circulation-derived macrophages in patients with glioma. A total of 40 patients with glioma and 38 healthy volunteers were recruited. The polarization status of macrophage-like cells in the peripheral blood of patients with glioma was evaluated. In addition, the associations between the polarization status of macrophage-like cells and glioma stage or the expression levels of the glioma tumor marker chitinase-3-like protein 1 (also termed YKL-40) were evaluated. The number of macrophage-like cells (CD115+CD1c-CD2-CD15-CD19-CD14+CD16+CD11b+) was higher in the peripheral blood of patients with glioma compared with that of healthy volunteers. There were fewer M1 macrophage-like cells, and more M2 macrophage-like cells were induced in the peripheral blood of patients with glioma compared with healthy controls. Specifically, the number of M2a/M2b macrophage-like cells increased, whereas that of M2c macrophage-like cells decreased in the peripheral blood of patients with glioma compared with healthy controls. The polarization status of macrophage-like cells in patients with glioma was not significantly associated with glioma stage or with the glioma marker YKL-40. Overall, the results of the present study revealed that the polarization status of macrophage-like cells in the peripheral blood of patients with glioma was abnormal, offering potential novel diagnostic and therapeutic targets, such as different macrophage subsets, for glioma.

The Development and Applications of a Dual Optical Imaging System for Studying Glioma Stem Cells

Glioblastoma multiforme represents one of the deadliest brain tumor types, manifested by a high rate of recurrence and poor prognosis. The presence of glioma stem cells (GSCs) can repopulate the tumor posttreatment and resist therapeutics. A better understanding of GSC biology is essential for developing more effective interventions. We established a CD133 promoter-driven dual reporter, expressing green fluorescent protein (GFP) and firefly luciferase (CD133-LG), capable for in vitro and in vivo imaging of CD133+ GSCs. We first demonstrated the reporter enabled in vitro analyses of GSCs. DBTRG-05MG (Denver Brain Tumor Research Group 05) carrying CD133-LG (DBTRG-05MG-CD133-LG) system reported increased GFP/luciferase activities in neurospheres. Additionally, we identified and isolated CD133+/GFP+ cells with increased tumorigenic properties, stemness markers, Notch1, β-catenin, and Bruton’s tyrosine kinase (Btk). Furthermore, prolonged temozolomide (TMZ) treatment enriched GSCs (reflected by increased percentage of CD133+ cells). Subsequently, Btk inhibitor, ibrutinib, suppressed GSC generation and stemness markers. Finally, we demonstrated real-time evaluation of anti-GSC function of ibrutinib in vivo with TMZ-enriched GSCs. Tumorigenesis was noninvasively monitored by bioluminescence imaging and mice that received ibrutinib showed a significantly lower tumor burden, indicating ibrutinib as a potential GSC inhibitor. In conclusion, we established a dual optical imaging system which enables the identification of CD133+ GSCs and screening for anti-GSC drugs.

Epithelial-to-mesenchymal transition as the driver of changing carcinoma and glioblastoma microenvironment

Epithelial-to-mesenchymal transition (EMT) is an essential molecular and cellular process that is part of normal embryogenesis and wound healing, and also has a ubiquitous role in various types of carcinoma and glioblastoma. EMT is activated and regulated by specific microenvironmental endogenous triggers and a complex network of signalling pathways. These mostly include epigenetic events that affect protein translation-controlling factors and proteases, altogether orchestrated by the switching on and off of oncogenes and tumour-suppressor genes in cancer cells. The hallmark of cancer-linked EMT is that the process is incomplete, as it is opposed by the reverse process of mesenchymal-to-epithelial transition, which results in a hybrid epithelial/mesenchymal phenotype that shows notable cell plasticity. This is a characteristic of cancer stem cells (CSCs), and it is of the utmost importance in their niche microenvironment, where it governs CSC migratory and invasive properties, thereby creating metastatic CSCs. These cells have high resistance to therapeutic treatments, in particular in glioblastoma.

Prognostic factor identification by analysis of the gene expression and DNA methylation data in glioma

Objective: This study was aimed to identify prognostic factors in glioma by analysis of the gene expression and DNA methylation data. Methods: The RNAseq and DNA methylation data associated with glioma were downloaded from GEO and TCGA databases to analyze the differentially expressed genes (DEGs) and methylated genes between tumor and normal tissues. Function and pathway analyses, co-expression network and survival analysis were performed based on these DEGs. The intersection genes of DEGs and differentially methylated genes were obtained followed by function analysis. Results: Total 2190 DEGs were identified between tumor and normal tissues, which were significantly enriched in neuron differentiation associated functions, as well as ribosome pathway. There were 6186 methylation sites (2834 up-regulated and 3352 down-regulated) with significant differences in tumor vs. normal. In the constructed co-expression network, DPP6, MAPK10 and RPL3 were hub genes. Survival analysis of 20 DEGs obtained 18 prognostic genes, among which 9 were differentially methylated, such as LHFPL tetraspan subfamily member 3 (LHFPL3), cadherin 20 (CDH20), complexin 2 (CPLX2), and tenascin R (TNR). The intersection of DEGs and differentially methylated genes (632 genes) were significantly enriched in functions of neuron differentiation. Conclusion: DPP6, MAPK10 and RPL3 may play important roles in tumorigenesis of glioma. Additionally, methylation of LHFPL3, CDH20, CPLX2, and TNR may serve as prognostic factors of glioma.

Biological effects of selective COX-2 inhibitor NS398 on human glioblastoma cell lines

Background

Cyclooxygenase-2 (COX-2), an inflammation-associated enzyme, has been implicated in tumorigenesis and progression of glioblastoma (GBM). The poor survival of GBM was mainly associated with the presence of glioma stem cells (GSC) and the markedly inflammatory microenvironment. To further explore the involvement of COX-2 in glioma biology, the effects of NS398, a selective COX-2 inhibitor, were evaluated on GSC derived from COX-2 expressing GBM cell lines, i.e., U87MG and T98G, in terms of neurospheres' growth, autophagy, and extracellular vesicle (EV) release.

Methods

Neurospheres' growth and morphology were evaluated by optical and scanning electron microscopy. Autophagy was measured by staining acidic vesicular organelles. Extracellular vesicles (EV), released from neurospheres, were analyzed by transmission electron microscopy. The autophagic proteins Beclin-1 and LC3B, as well as the EV markers CD63 and CD81, were analyzed by western blotting. The scratch assay test was used to evaluate the NS398 influence on GBM cell migration.

Results

Both cell lines were strongly influenced by NS398 exposure, as showed by morphological changes, reduced growth rate, and appearance of autophagy. Furthermore, the inhibitor led to a functional change of EV released by neurospheres. Indeed, EV secreted by NS398-treated GSC, but not those from control cells, were able to significantly inhibit adherent U87MG and T98G cell migration and induced autophagy in recipient cells, thus leading to effects quite similar to those directly caused by NS398 in the same cells.

Conclusion

Despite the intrinsic diversity and individual genetic features of U87MG and T98G, comparable effects were exerted by the COX-2 inhibitor NS398 on both GBM cell lines. Overall, our findings support the crucial role of the inflammatory-associated COX-2/PGE2 system in glioma and glioma stem cell biology.

LINC01198 facilitates gliomagenesis through activating PI3K/AKT pathway

Glioma is the most malignant primary brain cancer which frequently occurred in adults. In recent years, long-non coding RNAs (lncRNAs) have been demonstrated to play pivotal roles in human cancers. However, the role of most lncRNAs in gliomagenesis has not been probed. Presently, through TCGA, a novel lncRNA LINC01198 was found to be up-regulated and associated with clinical outcomes in glioblastoma multiforme (GBM). In our study, LINC01198 was proved to be up-regulated in glioma cell lines, and silenced LINC01198 curbed glioma cell proliferation and accelerated cell apoptosis. Importantly, we corroborated that LINC01198 activated the PI3 K/AKT pathway to aggravate glioma progression by targeting PIK3 CA and PTEN. Subsequently, LINC01198 was validated to localize in both cytoplasm and nucleus of glioma cells. Through mechanistic exploration, we illustrated that LINC01198 increased PIK3CA expression by sponging miR-129-5p in the cytoplasm. Furthermore, PTEN was transcriptionally repressed by REST/RCOR1/HDAC2 complex. More importantly, LINC01198 accelerated the assembly of REST/RCOR1/HDAC2 complex and recruited such complex to PTEN promoter so as to impair PTEN expression in glioma. Finally, we further verified that LINC01198 hindered glioma tumour growth in vivo through AKT-dependent manner. Jointly, LINC01198 activates PI3 K/AKT signalling to exert oncogenic function in gliomagenesis by regulating PIK3CA and PTEN, which highlights a new approach for glioma treatment.

Diffusion kurtosis imaging combined with molecular markers as a comprehensive approach to predict overall survival in patients with gliomas

PURPOSE

The purpose of this study was to explore the usefulness of diffusion kurtosis imaging (DKI) and molecular markers in predicting the prognosis of glioma patients.

METHOD

Fifty-one patients with gliomas were examined by conventional MRI and DKI at 3.0 T before operation. The mean kurtosis (MK), mean diffusivity (MD), axial kurtosis (AK), and radial kurtosis (RK) values of tumors were measured and normalized to the contralateral normal-appearing white matter. The molecular markers of gliomas, including isocitrate dehydrogenase-1 (IDH1), α thalassemia/mental retardation syndrome x-linked (ATRX) and O6-methylguanine-DNA methyltransferase (MGMT), were immunohistochemically stained on the resected tumor tissues. Statistical methods, including the chi-square test, independent sample t-test, receiver operating characteristic curve analysis, Kaplan-Meier curve analysis, and Cox regression analysis were performed.

RESULTS

The patients with lower MK, AK, RK, and higher MD values showed significantly better prognosis (P < 0.001). Survival time was better in glioma patients with IDH1 mutation (P < 0.01), ATRX loss of expression (P < 0.05), and MGMT negative expression (P < 0.05). However, among the groups of gliomas with IDH1 wild type, ATRX retention and those with MGMT positive expression, the patients with lower MK showed better outcome (P < 0.01). Cox multivariate regression analysis demonstrated that MK, RK values and ATRX retention could be used as independent prognostic risk factors, and high MK values had the highest risk for prognosis (HR = 65.288).

CONCLUSIONS

Molecular markers and DKI parameters, especially MK values, can be used to effectively evaluate the prognosis of glioma patients.

A risk signature with four autophagy-related genes for predicting survival of glioblastoma multiforme

Glioblastoma multiforme (GBM) is a devastating brain tumour without effective treatment. Recent studies have shown that autophagy is a promising therapeutic strategy for GBM. Therefore, it is necessary to identify novel biomarkers associated with autophagy in GBM. In this study, we downloaded autophagy-related genes from Human Autophagy Database (HADb) and Gene Set Enrichment Analysis (GSEA) website. Least absolute shrinkage and selection operator (LASSO) regression and multivariate Cox regression analysis were performed to identify genes for constructing a risk signature. A nomogram was developed by integrating the risk signature with clinicopathological factors. Time-dependent receiver operating characteristic (ROC) curve and calibration plot were used to evaluate the efficiency of the prognostic model. Finally, four autophagy-related genes (DIRAS3, LGALS8, MAPK8 and STAM) were identified and were used for constructing a risk signature, which proved to be an independent risk factor for GBM patients. Furthermore, a nomogram was developed based on the risk signature and clinicopathological factors (IDH1 status, age and history of radiotherapy or chemotherapy). ROC curve and calibration plot suggested the nomogram could accurately predict 1-, 3- and 5-year survival rate of GBM patients. For function analysis, the risk signature was associated with apoptosis, necrosis, immunity, inflammation response and MAPK signalling pathway. In conclusion, the risk signature with 4 autophagy-related genes could serve as an independent prognostic factor for GBM patients. Moreover, we developed a nomogram based on the risk signature and clinical traits which was validated to perform better for predicting 1-, 3- and 5-year survival rate of GBM.

Effects of progesterone on the cell number of gliomaspheres derived from human glioblastoma cell lines

AIMS

The malignancy of the Glioblastomas (GBM), the most frequent and aggressive brain tumors, have been associated with the presence of glioma stem cells (GSCs) which can form gliomaspheres (GS) in vitro. Progesterone (P) increases the proliferation, migration, and invasion of GBM cell lines through the interaction with its intracellular receptor (PR). However, it is unknown if the PR is expressed and the possible effects of P in the formation/differentiation of GS.

MAIN METHODS

GS were grown from U251 and U87 cell lines by selective culture with serum-free neural stem cell medium. GSCs were identified by the detection of Sox2, Ki67, Nestin, CD133, and CD15 by immunofluorescence. Additionally, the relative expression of PROM1, NES, SOX2, OLIG2, EZH2, BMI1 and PR genes was evaluated by RT-qPCR. The GS were treated with P, and the number of cells was quantified. By RT-PCR the βIII-TUB and GFAP differentiation genes were evaluated.

KEY FINDINGS

GS were maintained until passage four. The expression of all GSCs markers was significantly higher in GS as compared with the basal culture of U251 and U87 cells. We demonstrated for the first time that PR is expressed in GS and this expression was higher as compared with the U251 and U87 cells in basal conditions. Also, we observed that P increased the number of cells derived primary gliomaspheres (GS1) from the U251 line, as well as the expression of the neuronal differentiation marker βIII-TUB.

SIGNIFICANCE

These results suggest the participation of P in the growth of GSCs.

Long noncoding RNA MALAT1 may be a prognostic biomarker in IDH1/2 wild-type primary glioblastomas

Primary glioblastoma (GB) is the most aggressive type of brain tumors. While mutations in isocitrate dehydrogenase (IDH) genes are frequent in secondary GBs and correlate with a better prognosis, most primary GBs are IDH wild-type. Recent studies have shown that the long noncoding RNA metastasis associated lung adenocarcinoma transcript-1 (MALAT1) is associated with aggressive tumor phenotypes in different cancers. Our aim was to clarify the prognostic significance of MALAT1 in IDH1/2 wild-type primary GB tumors. We analyzed IDH1/2 mutation status in 75 patients with primary GB by DNA sequencing. The expression of MALAT1 was detected in the 75 primary GB tissues and 5 normal brain tissues using reverse transcription quantitative PCR (RT-qPCR). The associations between MALAT1 expression, IDH1/2 mutation status, and clinicopathological variables of patients were determined. IDH1 (R132H) mutation was observed in 5/75 primary GBs. IDH2 (R172H) mutation was not detected in any of our cases. MALAT1 expression was significantly upregulated in primary GB vs. normal brain tissues (p = 0.025). Increased MALAT1 expression in IDH1/2 wild-type primary GBs correlated with patient age and tumor localization (p = 0.032 and p = 0.025, respectively). A multivariate analysis showed that high MALAT1 expression was an unfavorable prognostic factor for overall survival (p = 0.034) in IDH1/2 wild-type primary GBs. High MALAT1 expression may have a prognostic role in primary GBs independent of IDH mutations.

Targeting Glutamine Addiction in Gliomas

The most common malignant brain tumors are those of astrocytic origin, gliomas, with the most aggressive glioblastoma (WHO grade IV) among them. Despite efforts, medicine has not made progress in terms of the prognosis and life expectancy of glioma patients. Behind the malignant phenotype of gliomas lies multiple genetic mutations leading to reprogramming of their metabolism, which gives those highly proliferating cells an advantage over healthy ones. The so-called glutamine addiction is a metabolic adaptation that supplements oxidative glycolysis in order to secure neoplastic cells with nutrients and energy in unfavorable conditions of hypoxia. The present review aims at presenting the research and clinical attempts targeting the different metabolic pathways involved in glutamine metabolism in gliomas. A brief description of the biochemistry of glutamine transport, synthesis, and glutaminolysis, etc. will forego a detailed comparison of the therapeutic strategies undertaken to inhibit glutamine utilization by gliomas.

Meningioma Tumor Microenvironment

The tumor microenvironment consists of noncancerous cells, such as immune cells and fibroblasts, and the proteins produced by these cells as well as the extracellular matrix components in the environment around a tumor. Tumor influences the behavior of the cells present in the surrounding environment, while the cells in the tumor microenvironment modulate the evolution of the tumor. Little is known about the microenvironment of meningioma, the most common benign intracranial tumor. Here, we review the current knowledge of the tumor microenvironment of meningioma and discusses its importance in meningioma tumorigenesis as well as in the designation of novel therapeutic approaches.

Splicing Dysregulation as Oncogenic Driver and Passenger Factor in Brain Tumors

Brain tumors are a heterogeneous group of neoplasms ranging from almost benign to highly aggressive phenotypes. The malignancy of these tumors mostly relies on gene expression reprogramming, which is frequently accompanied by the aberrant regulation of RNA processing mechanisms. In brain tumors, defects in alternative splicing result either from the dysregulation of expression and activity of splicing factors, or from mutations in the genes encoding splicing machinery components. Aberrant splicing regulation can generate dysfunctional proteins that lead to modification of fundamental physiological cellular processes, thus contributing to the development or progression of brain tumors. Herein, we summarize the current knowledge on splicing abnormalities in brain tumors and how these alterations contribute to the disease by sustaining proliferative signaling, escaping growth suppressors, or establishing a tumor microenvironment that fosters angiogenesis and intercellular communications. Lastly, we review recent efforts aimed at developing novel splicing-targeted cancer therapies, which employ oligonucleotide-based approaches or chemical modulators of alternative splicing that elicit an impact on brain tumor biology.

Novel approaches for glioblastoma treatment: Focus on tumor heterogeneity, treatment resistance, and computational tools

BACKGROUND

Glioblastoma (GBM) is a highly aggressive primary brain tumor. Currently, the suggested line of action is the surgical resection followed by radiotherapy and treatment with the adjuvant temozolomide, a DNA alkylating agent. However, the ability of tumor cells to deeply infiltrate the surrounding tissue makes complete resection quite impossible, and, in consequence, the probability of tumor recurrence is high, and the prognosis is not positive. GBM is highly heterogeneous and adapts to treatment in most individuals. Nevertheless, these mechanisms of adaption are unknown.

RECENT FINDINGS

In this review, we will discuss the recent discoveries in molecular and cellular heterogeneity, mechanisms of therapeutic resistance, and new technological approaches to identify new treatments for GBM. The combination of biology and computer resources allow the use of algorithms to apply artificial intelligence and machine learning approaches to identify potential therapeutic pathways and to identify new drug candidates.

CONCLUSION

These new approaches will generate a better understanding of GBM pathogenesis and will result in novel treatments to reduce or block the devastating consequences of brain cancers.

Promising Prognosis Marker Candidates on the Status of Epithelial-Mesenchymal Transition and Glioma Stem Cells in Glioblastoma

Multivariable analyses of global expression profiling are valid indicators of the prognosis of various diseases including brain cancers. To identify the candidates for markers of prognosis of glioblastoma, we performed multivariable analyses on the status of epithelial (EPI)-mesenchymal (MES) transition (EMT), glioma (GLI) stem cells (GSCs), molecular target therapy (MTT), and potential glioma biomarkers (PGBs) using the expression data and clinical information from patients. Random forest survival and Cox proportional hazards regression analyses indicated significant variable values for DSG3, CLDN1, CDH11, FN1, HDAC3/7, PTEN, L1CAM, OLIG2, TIMP4, IGFBP2, and GFAP. The analyses also comprised prognosis prediction formulae that could distinguish between the survival curves of the glioblastoma patients. In addition to the genes mentioned above, HDAC1, FLT1, EGFR, MGMT, PGF, STAT3, SIRT1, and GADD45A constituted complex genetic interaction networks. The calculated status scores obtained by principal component analysis indicated that GLI genes covered the status of EPI, GSC, and MTT-related genes. Moreover, survival tree analyses indicated that MES^high, MES^highGLI^low, GSC^highGLI^low, MES^highMTT^low, and PGB^high showed poor prognoses and MES^middle, GSC^low, and PGB^low showed good prognoses, suggesting that enhanced EMT and GSC are associated with poor survival and that lower expression of EPI markers and the pre-stages of EMT are relatively less malignant in glioblastoma. These results demonstrate that the assessment of EMT and GSC enables the prediction of the prognosis of glioblastoma that would help develop novel therapeutics and de novo marker candidates for the prognoses of glioblastoma.

The influence of patient sex on clinical approaches to malignant glioma

Gliomas are tumors that originate from the glial tissue, thus involving the central nervous system with varying degrees of malignancy. The most aggressive and frequent form is glioblastoma multiforme, a disease characterized by resistance to therapies, frequent recurrences, and extremely poor median survival time. Data on overall glioma case studies demonstrate clear sex disparities regarding incidence, prognosis, drug toxicity, clinical outcome, and, recently, prediction of therapeutic response. In this study, we analyze data in the literature regarding malignant glioma, mainly glioblastoma multiforme, focusing on epidemiological and clinical evaluations. Less discussed issues, such as the role of viral infections, energy metabolism, and predictive aspects concerning the possible use of dedicated therapeutic approaches for male or female patients, will be reported together with different estimated pathogenetic mechanisms underlying astrocyte transformation and glioma chemosensitivity. In this era, where personalized/precision medicine is the most important driver for targeted cancer therapies, the lines of evidence discussed herein strongly suggest that clinical approaches to malignant glioma should consider the patient's sex. Furthermore, retrospectively revising previous clinical studies considering patient sex as a crucial variable is recommended.

Mechanical Compression Regulates Brain Cancer Cell Migration Through MEK1/Erk1 Pathway Activation and GDF15 Expression

Mechanical compression is a common abnormality of brain tumors that has been shown to be responsible for the severe neurological defects of brain cancer patients representing a negative prognostic factor. Indeed, it is of note that patients that undergo resection exhibited higher survival rates than those subjected to biopsy only, suggesting that compressive forces generated during brain tumor growth play a key role in tumor progression. Despite the importance of mechanical compression in brain tumors, there is a lack of studies examining its direct effects on brain cancer cells and the mechanisms involved. In the present study, we used two brain cancer cell lines with distinct metastatic potential, the less aggressive H4 and the highly aggressive A172 cell lines, in order to study the effect of compression on their proliferative and migratory ability. Specifically, we used multicellular tumor spheroids (MCS) embedded in agarose matrix to show that compression strongly impaired their growth. Using mathematical modeling, we estimated the levels of compressive stress generated during the growth of brain MCS and then we applied the respective stress levels on brain cancer cell monolayers using our previously established transmembrane pressure device. By performing a scratch assay, we found that compression strongly induced the migration of the less aggressive H4 cells, while a less pronounced effect was observed for A172 cells. Analysis of the gene expression profile of both cell lines revealed that GDF15 and small GTPases are strongly regulated by mechanical compression, while GDF15 was further shown to be necessary for cells to migrate under compression. Through a phospho-proteomic screening, we further found that compressive stimulus is transmitted through the MEK1/Erk1 signaling pathway, which is also necessary for the migration of brain cancer cells. Finally, our results gave the first indication that GDF15 could regulate and being regulated by MEK1/Erk1 signaling pathway in order to facilitate the compression-induced brain cancer cell migration, rendering them along with small GTPases as potential targets for future anti-metastatic therapeutic innovations to treat brain tumors.

Identification of key candidate genes and pathways in glioblastoma by integrated bioinformatical analysis

Glioblastoma (GBM), characterized by high morbidity and mortality, is one of the most common lethal diseases worldwide. To identify the molecular mechanisms that contribute to the development of GBM, three cohort profile datasets (GSE50161, GSE90598 and GSE104291) were integrated and thoroughly analyzed; these datasets included 57 GBM cases and 22 cases of normal brain tissue. The current study identified differentially expressed genes (DEGs), and analyzed potential candidate genes and pathways. Additionally, a DEGs-associated protein-protein interaction (PPI) network was established for further investigation. Then, the hub genes associated with prognosis were identified using a Kaplan-Meier analysis based on The Cancer Genome Atlas database. Firstly, the current study identified 378 consistent DEGs (240 upregulated and 138 downregulated). Secondly, a cluster analysis of the DEGs was performed based on functions of the DEGs and signaling pathways were analyzed using the enrichment analysis tool on DAVID. Thirdly, 245 DEGs were identified using PPI network analysis. Among them, two co-expression modules comprising of 30 and 27 genes, respectively, and 35 hub genes were identified using Cytoscape MCODE. Finally, Kaplan-Meier analysis of the hub genes revealed that the increased expression of calcium-binding protein 1 (CABP1) was negatively associated with relapse-free survival. To summarize, all enriched Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways may participate in mechanisms underlying GBM occurrence and progression, however further studies are required. CABP1 may be a key gene associated with the biological process of GBM development and may be involved in a crucial mechanism of GBM progression.

Current and Future Trends on Diagnosis and Prognosis of Glioblastoma: From Molecular Biology to Proteomics

Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and to develop new personalized treatments. On these bases, the aim of this review article is to summarize the current knowledge regarding the application of molecular biology and proteomics techniques for the identification of novel biomarkers through the analysis of different biological samples obtained from glioblastoma patients, including DNA, microRNAs, proteins, small molecules, circulating tumor cells, extracellular vesicles, etc. Both benefits and pitfalls of molecular biology and proteomics analyses are discussed, including the different mass spectrometry-based analytical techniques, highlighting how these investigation strategies are powerful tools to study the biology of glioblastoma, as well as to develop advanced methods for the management of this pathology.

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.

Amide proton transfer imaging might predict survival and IDH mutation status in high-grade glioma

OBJECTIVES

To assess the utility of amide proton transfer (APT) imaging as an imaging biomarker to predict prognosis and molecular marker status in high-grade glioma (HGG, WHO grade III/IV).

METHODS

We included 71 patients with pathologically diagnosed HGG who underwent preoperative MRI with APT imaging. Overall survival (OS) and progression-free survival (PFS) according to APT signal, clinical factors, MGMT methylation status, and IDH mutation status were analyzed. Multivariate Cox regression models with and without APT signal data were constructed. Model performance was compared using the integrated AUC (iAUC). Associations between APT signals and molecular markers were assessed using the Mann-Whitney test.

RESULTS

High APT signal was a significant predictor for poor OS (HR = 3.21, 95% CI = 1.62-6.34) and PFS (HR = 2.22, 95% CI = 1.33-3.72) on univariate analysis. On multivariate analysis, high APT signals were an independent predictor of poor OS and PFS when clinical factors alone (OS: HR = 2.89; PFS: HR = 2.13), or in combination with molecular markers (OS: HR = 2.85; PFS: HR = 2.00), were included as covariates. The incremental prognostic value of APT signals was significant for OS and PFS. IDH-wild type was significantly associated with high APT signals (p = 0.001) when compared to IDH-mutant; however, there was no difference based on MGMT methylation status (p = 0.208).

CONCLUSION

High APT signal was a significant predictor of poor prognosis in HGG. APT data showed significant incremental prognostic value over clinical prognostic factors and molecular markers and may also predict IDH mutation status.

KEY POINTS

• Amide proton transfer (APT) imaging is a promising prognostic marker of high-grade glioma. • APT signals were significantly higher in IDH-wild type compared to IDH-mutant high-grade glioma. • APT imaging may be valuable for preoperative screening and treatment guidance.

Detection and Correlation of Single and Concomitant TP53, PTEN, and CDKN2A Alterations in Gliomas

Gliomas are the most frequent primary tumors of central nervous system and represent a heterogeneous group of tumors that originates from the glial cells. TP53, PTEN, and CDKN2A are important tumor suppressor genes that encode proteins involved in sustaining cellular homeostasis by different signaling pathways. Though genetic alterations in these genes play a significant role in tumorigenesis, few studies are available regarding the incidence and relation of concomitant TP53, PTEN, and CDKN2A alterations in gliomas. The purpose of this study was to evaluate the occurrence of mutation and deletion in these genes, through single-strand conformational polymorphism, array-comparative genomic hybridization, and fluorescence in situ hybridization techniques, in 69 gliomas samples. Molecular results demonstrated a significant higher prevalence of TP53, PTEN, and CDKN2A alterations in astrocytoma than other tumor subtypes, and heterozygous deletion was the most frequent event. In addition, a significant association was observed between TP53 and CDKN2A alterations (p = 0.0424), which tend to coexist in low grade astrocytomas (5/46 cases (10.9%)), suggesting that they are early events in development of these tumors, and PTEN and CDKN2A deletions (p = 0.0022), which occurred concomitantly in 9/50 (18%) patients, with CDKN2A changes preceding PTEN deletions, present preferably in high-grade gliomas.

Glioblastoma Stem Cells and Comparison of Isolation Methods

Background

Glioblastoma (GBM) is the most aggressive and the most common primary brain tumor. Over the last few years, studies have identified many genetical and phenotypical molecular situations for developing new treatment modalities in patients with GBM. Nevertheless, main problem for the GBM is radio-chemotherapy resistance and relapse after the surgery. The identification of glioma stem cells and microenvironmental influences has created a paradigm shift in targets of therapy. Current studies have shown that glioma stem cell is responsible for aggressiveness, recurrence and resistance to therapy of GBM. GBM stem cell isolated from human GBM multiforme fresh tissue samples is important both for curative therapeutic options and personalized targeted therapy. The purpose of this study was to determine the most suitable isolation method of GBM stem cells (GSCs).

Methods

Tumor tissue sample was obtained during the surgical resection of lesion in patients with the diagnosis of GBM. Tumor stem cell isolation from tissue was performed in three different ways: 1) GBM cell isolation with trypsin; 2) GBM cell isolation with brain tumor dissociation Kit (BTD Kit); and 3) GBM cell isolation with tumor dissociation enzyme (TDE).

Results

We showed that GSCs were isolated from tumor specimen using flow cytometry and immunofluorescence staining. Our study showed that isolation with BTD Kit is the most suitable method to isolate GBM tissue-derived glial tumor stem cells.

Conclusions

The development of alternative personalized therapies targeting brain tumor stem cell is urgently needed. It is important to understand the fundamental mechanisms of driving stem cells. If their life cycle mechanisms can be identified, we can control the growth of GBM.

Visualization of spatiotemporal dynamics of human glioma stem cell invasion

Glioblastoma exhibits phenotypic and genetic heterogeneity, aggressive invasiveness, therapeutic resistance, and tumor recurrence, which can be explained by the existence of glioma stem cells (GSCs). In this study, we visualized the spatiotemporal dynamics of invasion of human GSCs in an orthotopic xenograft mouse model using time-lapse imaging of organotypic brain slice cultures and three-dimensional imaging of optically cleared whole brains. GSCs implanted in the striatum exhibited directional migration toward axon bundles, perivascular area, and the subventricular zone around the inferior horn of the lateral ventricle. GSCs migrated in a helical pattern around axon bundles in the striatum and invaded broadly in both the rostral and caudal directions. GSCs in the corpus callosum migrated more rapidly and unidirectionally toward the contralateral side with pseudopod extension. These characteristics of GSC invasion shared histological features observed in glioblastoma patients. Spatiotemporal visualization techniques can contribute to the elucidation of the mechanisms underlying GSC invasion that may lead to the development of effective therapy for glioblastoma.

CEP55 promoted the migration, invasion and neuroshpere formation of the glioma cell line U251

Glioma stem cells (GSC) were important for Glioblastoma (GBM) initiation and chemotherapy resistance. Centrosomal protein of 55 kDa (CEP55) was a biomarker for multiple cancers. However, roles and mechanism of CEP55 in glioma tumorigenesis and stemness maintains of stem like cells was still unclear. U251 cells which stable overexpression or downregulation of CEP55 was obtained by lentivirus mediated transduction. Roles and mechanism of CEP55 in stemness maintains of stem like cells and tumorigenesis was investigated. Our results implied that knockdown the expression of CEP55 inhibited the invasion and migration of U251 cells, while overexpression of CEP55 displayed opposite results. Moreover, overexpression of CEP55 promoted neurosphere formation of glioma stem-like cells, while CEP55 knockdown decreased the number and size of neurosphere. Mechanistically, overexpression of CEP55 enhanced the expression of Forkhead box protein M1 (FOXM1), Matrix metalloproteinases (MMPs) and activated the NF-κB pathway, while knockdown CEP55 displayed opposite results. In conclusion, our results indicated that CEP55 played an important role in promoting the invasion and migration of U251 cell and self-renewal of glioma stem like cells which might be a new therapeutic target for glioma.

Novel Cancer Stem Marker and Its Applicability for Grading Primary Human Gliomas

Poorly differentiated cell populations including tumor-initiating stem cells have been demonstrated to display a unique ability to natively internalize fragmented double-stranded DNA. Using this feature as a marker, we show that 0.1% to 6% of human glioblastoma cells from the bioptates can effectively internalize a fluorescently labeled DNA probe. Of these, using samples from 3 patients, 66% to 100% cells are also positive for CD133, a well-established surface marker of tumor-initiating glioma stem cells. Using the samples from primary malignant brain lesions (33 patients), we demonstrate that tumor grading significantly correlates ( R = .71) with the percentage of DNA-internalizing cells. No such correlation is observed for relapse samples (18 patients).

Aberrations in DNA repair pathways in cancer and therapeutic significances

Cancer cells show various types of mutations and aberrant expression in genes involved in DNA repair responses. These alterations induce genome instability and promote carcinogenesis steps and cancer progression processes. These defects in DNA repair have also been considered as suitable targets for cancer therapies. A most effective target so far clinically demonstrated is "homologous recombination repair defect", such as BRCA1/2 mutations, shown to cause synthetic lethality with inhibitors of poly(ADP-ribose) polymerase (PARP), which in turn is involved in DNA repair as well as multiple physiological processes. Different approaches targeting genomic instability, including immune therapy targeting mismatch-repair deficiency, have also recently been demonstrated to be promising strategies. In these DNA repair targeting-strategies, common issues could be how to optimize treatment and suppress/conquer the development of drug resistance. In this article, we review the extending framework of DNA repair response pathways and the potential impact of exploiting those defects on cancer treatments, including chemotherapy, radiation therapy and immune therapy.

Arsenic Trioxide and (-)-Gossypol Synergistically Target Glioma Stem-Like Cells via Inhibition of Hedgehog and Notch Signaling

Glioblastoma is one of the deadliest malignancies and is virtually incurable. Accumulating evidence indicates that a small population of cells with a stem-like phenotype is the major culprit of tumor recurrence. Enhanced DNA repair capacity and expression of stemness marker genes are the main characteristics of these cells. Elimination of this population might delay or prevent tumor recurrence following radiochemotherapy. The aim of this study was to analyze whether interference with the Hedgehog signaling (Hh) pathway or combined Hh/Notch blockade using small-molecule inhibitors can efficiently target these cancer stem cells and sensitize them to therapy. Using tumor sphere lines and primary patient-derived glioma cultures we demonstrate that the Hh pathway inhibitor GANT61 (GANT) and the arsenic trioxide (ATO)-mediated Hh/Notch inhibition are capable to synergistically induce cell death in combination with the natural anticancer agent (−)-Gossypol (Gos). Only ATO in combination with Gos also strongly decreased stemness marker expression and prevented sphere formation and recovery. These synergistic effects were associated with distinct proteomic changes indicating diminished DNA repair and markedly reduced stemness. Finally, using an organotypic brain slice transplantation model, we show that combined ATO/Gos treatment elicits strong growth inhibition or even complete elimination of tumors. Collectively, our data show for the first time that ATO and Gos, two drugs that can be used in the clinic, represent a promising targeted therapy approach for the synergistic elimination of glioma stem-like cells.

Glioblastoma Stem-Like Cells, Metabolic Strategy to Kill a Challenging Target

Over the years, substantial evidence has definitively confirmed the existence of cancer stem-like cells within tumors such as Glioblastoma (GBM). The importance of Glioblastoma stem-like cells (GSCs) in tumor progression and relapse clearly highlights that cancer eradication requires killing of GSCs that are intrinsically resistant to conventional therapies as well as eradication of the non-GSCs cells since GSCs emergence relies on a dynamic process. The past decade of research highlights that metabolism is a significant player in tumor progression and actually might orchestrate it. The growing interest in cancer metabolism reprogrammation can lead to innovative approaches exploiting metabolic vulnerabilities of cancer cells. These approaches are challenging since they require overcoming the compensatory and adaptive responses of GSCs. In this review, we will summarize the current knowledge on GSCs with a particular focus on their metabolic complexity. We will also discuss potential approaches targeting GSCs metabolism to potentially improve clinical care.

Cytometric analysis of cell suspension generated by cavitron ultrasonic surgical aspirator in pediatric brain tumors

PURPOSE

The aim of this study was to test the possibility of using specimens obtained by a cavitron ultrasonic surgical aspirator (CUSA) in flow and mass cytometry investigations of pediatric brain tumors.

METHODS

CUSA specimens obtained from 19 pediatric patients with brain tumors were investigated. Flow and mass cytometry methods were applied to analyze the composition of material collected using the CUSA. Cell suspensions were prepared from CUSA aspirates. Then sample viability was assessed by conventional flow cytometry and subsequently stained with a panel of 31 metal-labeled antibodies.

RESULTS

Viability assessment was performed using conventional flow cytometry. Viability of cells in the acquired samples was below 50% in 16 of 19 cases. A mass cytometry investigation and subsequent analysis enabled us to discriminate brain tumor cells from contaminating leukocytes, whose proportions varied across the specimens. The addition of the viability marker cisplatin directly into the mass cytometry panel gave the means to selecting viable cells only for subsequent analyses. The proportion of non-viable cells was higher among tumor cells compared leukocytes.

CONCLUSIONS

When the analysis of the tumor cell immunophenotype is performed with markers for determining viability, the expression of the investigated markers can be evaluated. Suitable markers can be selected by high-throughput methods, such as mass cytometry, and those that are diagnostically relevant can be investigated using flow cytometry, which is more flexible in terms of time.

Analyses of temporal and spatial patterns of glioblastoma multiforme and other brain cancer subtypes in relation to mobile phones using synthetic counterfactuals

This study assesses whether temporal trends in glioblastoma multiforme (GBM) in different brain regions, and of different malignant and benign (including acoustic neuroma and meningioma) subtypes in the temporal lobe, could be associated with mobile phone use. Annual 1985-2005 incidence of brain cancer subtypes for England were linked to population-level covariates. Bayesian structural timeseries were used to create 2006-2014 counterfactual trends, and differences with measured newly diagnosed cases were interpreted as causal effects. Increases in excess of the counterfactuals for GBM were found in the temporal (+38% [95% Credible Interval -7%,78%]) and frontal (+36% [-8%,77%]) lobes, which were in agreement with hypothesised temporal and spatial mechanisms of mobile phone usage, and cerebellum (+59% [-0%,120%]). However, effects were primarily present in older age groups, with largest effects in 75 + and 85 + groups, indicating mobile phone use is unlikely to have been an important putative factor. There was no evidence of an effect of mobile phone use on incidence of acoustic neuroma and meningioma. Although 1985-2014 trends in GBM in the temporal and frontal lobes, and probably cerebellum, seem consistent with mobile phone use as an important putative factor, age-group specific analyses indicate that it is unlikely that this correlation is causal.

A Risk Classification System With Five-Gene for Survival Prediction of Glioblastoma Patients

Objective: Glioblastoma (GBM) is the most common and fatal primary brain tumor in adults. It is necessary to identify novel and effective biomarkers or risk signatures for GBM patients. Methods: Differentially expressed genes (DEGs) between GBM and low-grade glioma (LGG) in TCGA samples were screened out and weight correlation network analysis (WGCNA) was performed to confirm WHO grade-related genes. Five genes were selected via multivariate Cox proportional hazards regression analysis and were used to construct a risk signature. A nomogram composed of the risk signature and clinical characters (age, radiotherapy, and chemotherapy experience) was established to predict 1, 3, 5-year survival rate for GBM patients. Results: One hundred ninety-four DEGs in blue gene module were found to be positively related to WHO grade via WGCNA. Five genes (DES, RANBP17, CLEC5A, HOXC11, POSTN) were selected to construct a risk signature for GBM via R language. This risk signature was identified to independently predict the outcome of GBM patients, as well as stratified by IDH1 status, MGMT promoter status, and radio-chemotherapy. The nomogram was established which combined the risk signature with clinical factors. The results of c-index, ROC curve and calibration plot revealed the nomogram showing a good accuracy for predicting 1, 3, or 5-year survival of GBM patients. Conclusion: The risk signature with five genes could serve as an independent factor for predicting the prognosis of patients with GBM. Moreover, the nomogram with the risk signature and clinical traits proved to perform better for predicting 1, 3, 5-year survival rate.

Dynamic expression of 11 miRNAs in 83 consecutive primary and corresponding recurrent glioblastoma: correlation to treatment, time to recurrence, overall survival and MGMT methylation status

Background

Glioblastoma (GBM) is the most common and the most malignant glioma subtype. Among numerous genetic alterations, miRNAs contribute to pathogenesis of GBM and it is suggested that also to GBM recurrence and resistance to therapy. Based on publications, we have selected 11 miRNAs and analyzed their expression in GBM. We hypothesized that selected miRNAs are differentially expressed and involved in primary as well as in recurrent GBM, that show significant expressional differences when different treatment options are in question, and that are related to certain patients and tumor characteristics.

Patients and methods

Paraffin embedded tissues, obtained from primary and corresponding recurrent tumor from 83 patients with primary GBM were used. Eleven miRNAs (miR-7, miR-9, miR-15b, miR-21, miR-26b, miR-124a, miR-199a, let-7a, let-7b, let-7d, and let-7f) were selected for qPCR expression analysis. For patients who received temozolamide (TMZ) as chemotherapeutic drug, O6-methylguanine-DNA methyltransferase (MGMT) methylation status was defined using the methyl-specific PCR.

Results

There was a significant change in expression of miR-7, miR-9, miR-21, miR-26b, mirR-124a, miR-199a and let-7f in recurrent tumor compared to the primary. In recurrent tumor, miR-15b, let-7d and let-7f significantly changed comparing both treatment options. We also observed difference in progression free survival between patients that received radiotherapy and patients that received radiotherapy and chemotherapy, and longer survival for patients who received chemotherapy after second surgery compared to not treated patients. miR-26b showed correlation to progression free survival and let-7f to overall survival. We did not find any expression difference between the tumors with and without methylated MGMT.

Conclusions

Our data suggest that analyzed miRNAs may not only contribute to pathogenesis of primary GBM, but also to tumor progression and its recurrence. Moreover, expression of certain miRNAs appears to be therapy-dependent and as such they might serve as additional biomarker for recurrence prediction and potentially predict a therapy-resistance.

Comparison of Survival Outcomes Between Partial Resection and Biopsy for Primary Glioblastoma: A Propensity Score-Matched Study

OBJECTIVES

Gross total resection for glioblastoma (GBM) has been associated with better prognosis. However, it is not always feasible, and the threshold for the extent of resection required for better prognosis has been controversial. Therefore, we compared the survival and clinical outcomes of patients with GBM who had undergone partial resection (PR) or biopsy.

METHODS

Of the 110 patients, 32 and 78, who had undergone PR and biopsy, respectively, were enrolled to identify any differences in clinical outcomes. No differences were found in patient demographics between the 2 groups, except for tumor location and mean tumor volume (P = 0.02 and P < 0.01, respectively). Propensity score matching between the PR and biopsy groups was performed, in which 20 patients each in the PR and biopsy groups were matched.

RESULTS

The overall survival (OS) and progression-free survival (PFS) did not differ significantly between the PR and biopsy groups (P = 0.84 and P = 0.48, respectively). After propensity score matching, the differences in OS and PFS between the 2 groups were still not statistically significant (P = 0.51 and P = 0.75, respectively). The hazard ratios for OS and PFS for the PR group compared with biopsy were 0.98 and 0.73, respectively; however, the difference was not statistically significant (P = 0.96 and P = 0.39, respectively). The surgical complication rate was greater in the PR group (14 of 32; 43.7%) than in the biopsy group (9 of 78; 11.5%; P < 0.01).

CONCLUSIONS

PR failed to improve survival compared with biopsy for patients with GBM. Moreover, the surgical complication rate in the PR group was greater than that in the biopsy group.

Regulating glioma stem cells by hypoxia through the Notch1 and Oct3/4 signaling pathway

To investigate the effects of hypoxia on the features of cancer stem cells in the glioma cancer U87 cell line and underlying mechanism, stem cell markers and features in U87 were studied under the hypoxic and normoxic culture conditions by reverse transcription-quantitative polymerase chain reaction, western blot analysis, MTT, a colony formation test and flow cytometry. Compared to the normoxic group, the cluster of differentiation 133+ phenotype, clone formation rate and cell vitality were significantly elevated in U87 cells cultured in a hypoxic microenvironment. Also, the mRNA and protein expression of neurogenic locus notch homolog protein 1 (Notch1) and Oct3/4 were significantly elevated in U87 cells cultured in a hypoxic microenvironment, however, transcription factor SOX-2 expression was not significantly changed. These results indicate that hypoxia can promote the proliferation of glioma stem cells and maintain the characteristics of stem cells through the activation of Notch1 and Oct3/4 or Notch1 activation, affecting the biological characteristics of glioma cells.

Inhibition of Chloride Intracellular Channel 1 (CLIC1) as Biguanide Class-Effect to Impair Human Glioblastoma Stem Cell Viability

The antidiabetic biguanide metformin exerts antiproliferative effects in different solid tumors. However, during preclinical studies, metformin concentrations required to induce cell growth arrest were invariably within the mM range, thus difficult to translate in a clinical setting. Consequently, the search for more potent metformin derivatives is a current goal for new drug development. Although several cell-specific intracellular mechanisms contribute to the anti-tumor activity of metformin, the inhibition of the chloride intracellular channel 1 activity (CLIC1) at G1/S transition is a key events in metformin antiproliferative effect in glioblastoma stem cells (GSCs). Here we tested several known biguanide-related drugs for the ability to affect glioblastoma (but not normal) stem cell viability, and in particular: phenformin, a withdrawn antidiabetic drug; moroxydine, a former antiviral agent; and proguanil, an antimalarial compound, all of them possessing a linear biguanide structure as metformin; moreover, we evaluated cycloguanil, the active form of proguanil, characterized by a cyclized biguanide moiety. All these drugs caused a significant impairment of GSC proliferation, invasiveness, and self-renewal reaching IC₅₀ values significantly lower than metformin, (range 0.054–0.53 mM vs. 9.4 mM of metformin). All biguanides inhibited CLIC1-mediated ion current, showing the same potency observed in the antiproliferative effects, with the exception of proguanil which was ineffective. These effects were specific for GSCs, since no (or little) cytotoxicity was observed in normal umbilical cord mesenchymal stem cells, whose viability was not affected by metformin and moroxydine, while cycloguanil and phenformin induced toxicity only at much higher concentrations than required to reduce GSC proliferation or invasiveness. Conversely, proguanil was highly cytotoxic also for normal mesenchymal stem cells. In conclusion, the inhibition of CLIC1 activity represents a biguanide class-effect to impair GSC viability, invasiveness, and self-renewal, although dissimilarities among different drugs were observed as far as potency, efficacy and selectivity as CLIC1 inhibitors. Being CLIC1 constitutively active in GSCs, this feature is relevant to grant the molecules with high specificity toward GSCs while sparing normal cells. These results could represent the basis for the development of novel biguanide-structured molecules, characterized by high antitumor efficacy and safe toxicological profile.