Influence of p53 mutations on prognosis of patients with glioblastoma

Synergistic Effect of a Combination of Proteasome and Ribonucleotide Reductase Inhibitors in a Biochemical Model of the Yeast Saccharomyces cerevisiae and a Glioblastoma Cell Line

Proteasome inhibitors are used in the therapy of several cancers, and clinical trials are underway for their use in the treatment of glioblastoma (GBM). However, GBM becomes resistant to chemotherapy relatively rapidly. Recently, the overexpression of ribonucleotide reductase (RNR) genes was found to mediate therapy resistance in GBM. The use of combinations of chemotherapeutic agents is considered a promising direction in cancer therapy. The present work aimed to evaluate the efficacy of the combination of proteasome and RNR inhibitors in yeast and GBM cell models. We have shown that impaired proteasome function results in increased levels of RNR subunits and increased enzyme activity in yeast. Co-administration of the proteasome inhibitor bortezomib and the RNR inhibitor hydroxyurea was found to significantly reduce the growth rate of S. cerevisiae yeast. Accordingly, the combination of bortezomib and another RNR inhibitor gemcitabine reduced the survival of DBTRG-05MG compared to the HEK293 cell line. Thus, yeast can be used as a simple model to evaluate the efficacy of combinations of proteasome and RNR inhibitors.

Haploinsufficiency of Adenomatous Polyposis Coli Coupled with Kirsten Rat Sarcoma Viral Oncogene Homologue Activation and P53 Loss Provokes High-Grade Glioblastoma Formation in Mice

Glioblastoma multiforme (GBM) is the most common and deadly type of brain tumor originating from glial cells. Despite decades of clinical trials and research, there has been limited success in improving survival rates. However, molecular pathology studies have provided a detailed understanding of the genetic alterations associated with the formation and progression of glioblastoma-such as Kirsten rat sarcoma viral oncogene homolog (KRAS) signaling activation (5%), P53 mutations (25%), and adenomatous polyposis coli (APC) alterations (2%)-laying the groundwork for further investigation into the biological and biochemical basis of this malignancy. These analyses have been crucial in revealing the sequential appearance of specific genetic lesions at distinct histopathological stages during the development of GBM. To further explore the pathogenesis and progression of glioblastoma, here, we developed the glial-fibrillary-acidic-protein (GFAP)-Cre-driven mouse model and demonstrated that activated KRAS and p53 deficiencies play distinct and cooperative roles in initiating glioma tumorigenesis. Additionally, the combination of APC haploinsufficiency with mutant Kras activation and p53 deletion resulted in the rapid progression of GBM, characterized by perivascular inflammation, large necrotic areas, and multinucleated giant cells. Consequently, our GBM models have proven to be invaluable resources for identifying early disease biomarkers in glioblastoma, as they closely mimic the human disease. The insights gained from these models may pave the way for potential advancements in the diagnosis and treatment of this challenging brain tumor.

Identification of BST2 Contributing to the Development of Glioblastoma Based on Bioinformatics Analysis

Rigorous molecular analysis of the immune cell environment and immune response of human tumors has led to immune checkpoint inhibitors as one of the most promising strategies for the treatment of human cancer. However, in human glioblastoma multiforme (GBM) which develops in part by attracting immune cell types intrinsic to the human brain (microglia), standard immunotherapy has yielded inconsistent results in experimental models and patients. Here, we analyzed publicly available expression datasets to identify molecules possibly associated with immune response originating from or influencing the tumor microenvironment in primary tumor samples. Using three glioma datasets (GSE16011, Rembrandt-glioma and TCGA-glioma), we first analyzed the data to distinguish between GBMs of high and low tumor cell purity, a reflection of the cellular composition of the tumor microenvironment, and second, to identify differentially expressed genes (DEGs) between these two groups using GSEA and other analyses. Tumor purity was negatively correlated with patient prognosis. The interferon gamma-related gene BST2 emerged as a DEG that was highly expressed in GBM and negatively correlated with tumor purity. BST2^high tumors also tended to harbor PTEN mutations (31 vs. 9%, BST2^high versus BST2^low) while BST2^low tumors more often had sustained TP53 mutations (8 versus 36%, BST2^high versus BST2^low). Prognosis of patients with BST2^high tumors was also poor relative to patients with BST2^low tumors. Further molecular in silico analysis demonstrated that high expression of BST2 was negatively correlated with CD8⁺ T cells but positively correlated with macrophages with an M2 phenotype. Further functional analysis demonstrated that BST2 was associated with multiple immune checkpoints and cytokines, and may promote tumorigenesis and progression through interferon gamma, IL6/JAK/STAT3 signaling, IL2/STAT5 signaling and the TNF-α signaling via NF-kB pathway. Finally, a series of experiments confirmed that the expression of BST2 can be significantly increased by IFN induction, and knockdown of BST2 can significantly inhibit the growth and invasion of GBM cells, and may affect the phenotype of tumor-associated macrophages. In conclusion, BST2 may promote the progression of GBM and may be a target for treatment.

Multivariate analysis of associations between clinical sequencing and outcome in glioblastoma

BACKGROUND

Many factors impact survival in patients with glioblastoma, including age, Karnofsky Performance Status, postoperative chemoradiation, IDH1/2 mutation status, MGMT promoter methylation status, and extent of resection. High-throughput next-generation sequencing is a widely available diagnostic tool, but the independent impact of tumors harboring specific mutant genes on survival and the efficacy of extent of resection are not clear.

METHODS

We utilized a widely available diagnostic platform (FoundationOne CDx) to perform high-throughput next-generation sequencing on 185 patients with newly diagnosed glioblastoma in our tertiary care center. We performed multivariate analysis to control for clinical parameters with known impact on survival to elucidate the independent prognostic value of prevalent mutant genes and the independent impact of gross total resection.

RESULTS

When controlling for factors with known prognostic significance including IDH1/2 mutation and after multiple comparisons analysis, CDKN2B and EGFR mutations were associated with reduced overall survival while PTEN mutation was associated with improved overall survival. Gross total resection, compared to other extent of resection, was associated with improved overall survival in patients with tumors harboring mutations in CDKN2A, CDKN2B, EGFR, PTEN, TERT promoter, and TP53. All patients possessed at least one of these 6 mutant genes.

CONCLUSIONS

This study verifies the independent prognostic value of several mutant genes in glioblastoma. Six commonly found mutant genes were associated with improved survival when gross total resection was achieved. Thus, even when accounting for known predictors of survival and multiple mutant gene comparisons, extent of resection continues to be strongly associated with survival.

Biomarkers of Systemic Inflammation in Patients with Glioblastoma: An Analysis of Correlation with Tumour-Related Factors and Survival

Background

Biomarkers of systemic inflammation (BMSIs), including haemogram cell counts (CC, e.g., absolute neutrophil count) and cell count-ratios (CCR, e.g., the neutrophil-lymphocyte ratio, etc.), have been found to have prognostic significance in many solid-organ cancers.

Aims

In this three-part study, we first examined if the CCs and CCRs were altered in patients with glioblastoma (GBM) when compared with healthy controls. Second, we evaluated for any correlation between the BMSIs and patient- and tumour-related factors. Third, we evaluated the influence of the CCs and CCRs on survival.

Methods

This was a retrospective analysis of patients who underwent surgery/biopsy for a newly diagnosed brain tumour that was subsequently confirmed to be GBM (Cases). Controls were healthy individuals who underwent pre-employment screening blood tests.

Statistical Methods

Parametric tests were used to compare normally distributed continuous variables, whereas non-normally distributed variables were compared using non-parametric tests. Thresholds for the BMSIs were determined using X-tile analysis. Cox regression using the proportional hazards model was used for survival analyses around the determined thresholds.

Results

All CCs and CCRs were altered in Cases compared with Controls. Presentation with raised intracranial pressure, altered sensorium, poor performance status, loss of ATRX, and lack of p53 overexpression was associated with an inflammatory phenotype of changes in the BMSIs. The inflammatory phenotype of changes was associated with poor survival.

Conclusions

A significant inflammatory response was found in patients with GBM and correlated with clinical features, the molecular profile of the tumour and poor survival.

MicroRNA-744-5p inhibits glioblastoma malignancy by suppressing replication factor C subunit 2

Glioblastoma (GBM) is the most common malignant primary brain tumor, accounting for ~57% of all gliomas and 48% of all malignant primary central nervous system tumors in the United States. Abnormal expression of the replication factor C subunit 2 (RFC2) gene and microRNA (miR)-744-5p is associated with tumorigenic characteristics, including cellular proliferation, migration and invasiveness. However, the mechanism underlying the interaction between miR-744-5p and RFC2 in GBM remains unknown. Reverse transcription-quantitative (RT-q) PCR analysis of RFC2 and miR-744-5p was performed using GBM tumor tissues and cells, and the association between miR-744-5p and RFC2 was determined by dual-luciferase reporter assay. Cell Counting Kit 8, 5-bromo-2-deoxyuridine (BrdU), wound-healing and cellular adhesion assays, as well as the detection of caspase-3 activity and western blotting were used to detect cellular proliferation, migration and adhesion, caspase-3 activity, and Bax and Bcl-2 protein expression, respectively, in GBM cells. The results of the present study demonstrated that RFC2 expression was increased in GBM tissues and cell lines. Overexpression of RFC2 promoted cellular proliferation, migration, adhesion and an increase in Bcl-2 protein levels, and suppressed cellular caspase-3 activity and Bax protein expression, while silencing RFC2 resulted in the opposite effect. The effects of miR-744-5p inhibition were similar to those of RFC2 overexpression. Moreover, miR-744-5p was found to target RFC2 in GBM cells, and inhibiting the expression of RFC2 suppressed GBM tumorigenesis. In conclusion, the present study demonstrated that miR-744-5p targets RFC2 and suppresses the progression of GBM by repressing cellular proliferation, migration and Bcl-2 protein expression, and effectively promoting caspase-3 activity and Bax protein expression. These findings suggest a new target for the clinical treatment and improved prognosis of patients with GBM in the future.

The combined effect of neutron irradiation and temozolomide on glioblastoma cell lines with different MGMT and P53 status

Temozolomide (TMZ) is a DNA-alkylating agent used for chemo-radiotherapy of glioblastoma, which is also a target cancer for boron neutron capture therapy (BNCT). Although the DNA-repair enzyme O⁶-methylguanine DNA methyltransferase (MGMT) and the tumor suppressor p53 are mutated in some glioblastoma cells, it remains unknown whether these mutations affect sensitivity to neutron irradiation. We examined sensitivity to neutron irradiation and TMZ in two glioblastoma cell lines: T98G, which is p53-mutant with high levels of MGMT activity; and A172, which is p53-wild-type and has low MGMT activity. T98G cells were more resistant to TMZ treatment than A172 cells, with a 10-fold higher LC50. In A172 cells, TMZ treatment did not change the cell-killing effect of neutron irradiation in the presence of borono-phenylalanine (BPA). By contrast, T98G cells were more resistant to neutron irradiation when BPA was present. These results indicate that DNA repair activity in T98G cells might be higher due to upregulation of MGMT after TMZ treatment. Thus, differences in the MGMT and p53 statuses of glioblastoma cells might predict the effect of combination therapy with BNCT and DNA-alkylating agent.

Antimicrobial Peptide TP4 Induces ROS-Mediated Necrosis by Triggering Mitochondrial Dysfunction in Wild-Type and Mutant p53 Glioblastoma Cells

Antimicrobial peptide tilapia piscidin 4 (TP4) from Oreochromis niloticus exhibits potent bactericidal and anti-tumorigenic effects. In a variety of cancers, the mutation status of p53 is a decisive factor for therapeutic sensitivity. Therefore, we investigated the impact of p53 status on TP4-induced cytotoxicity in glioblastoma cell lines and the molecular mechanisms that govern cytotoxic effects. Both U87MG (wild-type/WT p53) and U251 (mutant p53) glioblastoma cell lines were sensitive to TP4-induced cytotoxicity. The necrosis inhibitors Necrostatin-1 and GSK’872 attenuated TP4-induced cytotoxicity, and TP4 treatment induced the release of cyclophilin A, a biomarker of necrosis. Moreover, TP4 induced mitochondrial hyperpolarization and dysfunction, which preceded the elevation of intracellular reactive oxygen species, DNA damage, and necrotic cell death in both U87MG and U251 glioblastoma cells. p38 was also activated by TP4, but did not contribute to cytotoxicity. SB202190, a specific p38 inhibitor, enhanced TP4-induced oxidative stress, mitochondrial dysfunction, and cytotoxicity, suggesting a protective role of p38. Furthermore, TP4-induced cytotoxicity, oxidative stress, phosphorylation of p38, and DNA damage were all attenuated by the mitochondrial-targeted reactive oxygen species (ROS) scavenger MitoTEMPO, or the reactive oxygen species scavenger N-acetyl-L-cysteine. Based on these data, we conclude that TP4 induces necrosis in both WT and mutant p53 glioblastoma cells through a mitochondrial ROS-dependent pathway.

Attenuation of Tumor Suppressive Function of FBXO16 Ubiquitin Ligase Activates Wnt Signaling In Glioblastoma

Glioblastoma (GBM) is one of the most aggressive and lethal types of brain tumor. Despite the advancements in conventional or targeted therapies, median survival of GBM patients is less than 12 months. Amongst various signaling pathways aberrantly activated in glioma, active Wnt/β-catenin signaling pathway is one of the crucial oncogenic players. β-catenin, an important mediator of Wnt signaling pathway, gets phosphorylated by GSK3β complex. Phosphorylated β-catenin is specifically recognized by β-Trcp1, a F-box/WD40-repeat protein and with the help of Skp1 it plays a central role in recruiting phosphorylated β-catenin for degradation. In GBM, expression of β-TrCP1 and its affinity for β catenin is reported to be very low. Hence, we investigated whether any other members of the E3 ubiquitin ligase family could be involved in degradation of nuclear β-catenin. We here report that FBXO16, a component of SCF E3 ubiquitin ligase complex, is an interacting protein partner for β-catenin and mediates its degradation. Next, we show that FBXO16 functions as a tumor suppressor in GBM. Under normal growth conditions, FBXO16 proteasomally degrades β-catenin in a GSK-3β independent manner. Specifically, the C-terminal region of FBXO16 targets the nuclear β-catenin for degradation and inhibits TCF4/LEF1 dependent Wnt signaling pathway. The nuclear fraction of β-catenin undergoes K-48 linked poly-ubiquitination in presence of FBXO16. In summary, we show that due to low expression of FBXO16, the β-catenin is not targeted in glioma cells leading to its nuclear accumulation resulting in active Wnt signaling. Activated Wnt signaling potentiates the glioma cells toward a highly proliferative and malignant state.

Genetics of Glioblastoma in Moroccan population: Review of literature

Glioblastoma is the most aggressive malignant type of central nervous system tumors. The literature review revealed that the most common genetic abnormalities in primary and secondary glioblastomas are IDH1 / 2 mutations, p53 mutations, and overexpression of EGFR. To our knowledge, this is the first Moroccan study to provide a global picture of genetic studies performed on Moroccan patients to describe genetic markers and their frequency in our population. An in-depth research in ScienceDirect and Pubmed on glioblastoma articles treated in Morocco, this research is based on the following keywords: glioblastoma in Morocco, primary glioblastoma in Morocco, secondary glioblastoma in Morocco. We found only three research articles on genomic alteration of IDH1 / 2, p53 and EGFR expression. The frequency of these gene mutations in our population was similar to those reported from other populations. Additional molecular studies need to be performed on other genes to describe other genetic markers in the Moroccan population.

Treatment of Glioblastoma in the Elderly

Clinical research in neuro-oncology frequently classifies patients over 60-70 years of age as 'elderly', a designation intended to identify patients with the disease characteristics, psychosocial changes, and susceptibility to treatment toxicities associated with advancing age. The elderly account for a large proportion of patients diagnosed with glioblastoma (GBM), and this population is projected to increase. Their prognosis is inferior to that of GBM patients as a whole, and concerns over treatment toxicity may limit the aggressiveness with which they are treated. Recent clinical studies have assisted with therapeutic decision making in this cohort. Hypofractionated radiation with concurrent and adjuvant temozolomide has been shown to increase survival without worsened quality of life in elderly patients with good functional status. Single modality radiation therapy or temozolomide therapy are frequently used in this population, and while neither has demonstrated superiority, O⁶-methylguanine-DNA methyltransferase (MGMT) methylation status is predictive of improved survival with temozolomide over radiation therapy. Despite these advances, ambiguity as to how to best define, assess, and treat this population remains. The specific response of elderly patients to emerging therapies, such as immunotherapies, is unclear. Advancing outcomes for elderly patients with GBM requires persistent efforts to include them in translational and clinical research endeavors, and concurrent dedication to the preservation of function and quality of life in this population.

Using genomics to guide treatment for glioblastoma

Glioblastoma has been shown to have many different genetic mutations found both within and between tumor samples. Molecular testing and genomic sequencing has helped to classify diagnoses and clarify difficult to interpret histopathological specimens. Genomic information also plays a critical role in prognostication for patients, with IDH mutations and MGMT methylation having significant impact of the response to chemotherapy and overall survival of patients. Unfortunately, personalized medicine and targeted therapy against specific mutations have not been shown to improve patient outcomes. As technology continues to improve, exome and RNA sequencing will play a role in the design of clinical trials, classification of patient subgroups and identification of rare mutations that can be targeted by small-molecule inhibitors and biologic agents.

TP53 gain-of-function mutation promotes inflammation in glioblastoma

Glioblastoma (GBM), the most severe and common brain tumor in adults, is characterized by multiple somatic mutations and aberrant activation of inflammatory responses. Immune cell infiltration and subsequent inflammation cause tumor growth and resistance to therapy. Somatic loss-of-function mutations in the gene encoding tumor suppressor protein p53 (TP53) are frequently observed in various cancers. However, numerous studies suggest that TP53 regulates malignant phenotypes by gain-of-function (GOF) mutations. Here we demonstrate that a TP53 GOF mutation promotes inflammation in GBM. Ectopic expression of a TP53 GOF mutant induced transcriptomic changes, which resulted in enrichment of gene signatures related to inflammation and chemotaxis. Bioinformatics analyses revealed that a gene signature, upregulated by the TP53 GOF mutation, is associated with progression and shorter overall survival in GBM. We also observed significant correlations between the TP53 GOF mutation signature and inflammation in the clinical database of GBM and other cancers. The TP53 GOF mutant showed upregulated C-C motif chemokine ligand 2 (CCL2) and tumor necrosis factor alpha (TNFA) expression via nuclear factor kappa B (NFκB) signaling, consequently increasing microglia and monocyte-derived immune cell infiltration. Additionally, TP53 GOF mutation and CCL2 and TNFA expression correlated positively with tumor-associated immunity in patients with GBM. Taken together, our findings suggest that the TP53 GOF mutation plays a crucial role in inflammatory responses, thereby deteriorating prognostic outcomes in patients with GBM.

Inferring network structure in non-normal and mixed discrete-continuous genomic data

Inferring dependence structure through undirected graphs is crucial for uncovering the major modes of multivariate interaction among high-dimensional genomic markers that are potentially associated with cancer. Traditionally, conditional independence has been studied using sparse Gaussian graphical models for continuous data and sparse Ising models for discrete data. However, there are two clear situations when these approaches are inadequate. The first occurs when the data are continuous but display non-normal marginal behavior such as heavy tails or skewness, rendering an assumption of normality inappropriate. The second occurs when a part of the data is ordinal or discrete (e.g., presence or absence of a mutation) and the other part is continuous (e.g., expression levels of genes or proteins). In this case, the existing Bayesian approaches typically employ a latent variable framework for the discrete part that precludes inferring conditional independence among the data that are actually observed. The current article overcomes these two challenges in a unified framework using Gaussian scale mixtures. Our framework is able to handle continuous data that are not normal and data that are of mixed continuous and discrete nature, while still being able to infer a sparse conditional sign independence structure among the observed data. Extensive performance comparison in simulations with alternative techniques and an analysis of a real cancer genomics data set demonstrate the effectiveness of the proposed approach.

Artesunate enhances the therapeutic response of glioma cells to temozolomide by inhibition of homologous recombination and senescence

Glioblastoma multiforme (GBM), a malignant brain tumor with a dismal prognosis, shows a high level of chemo- and radioresistance and, therefore, attempts to sensitize glioma cells are highly desired. Here, we addressed the question of whether artesunate (ART), a drug currently used in the treatment of malaria, enhances the killing response of glioblastoma cells to temozolomide (TMZ), which is the first-line therapeutic for GBM. We measured apoptosis, necrosis, autophagy and senescence, and the extent of DNA damage in glioblastoma cells. Further, we determined the tumor growth in nude mice. We show that ART enhances the killing effect of TMZ in glioblastoma cell lines and in glioblastoma stem-like cells. The DNA double-strand break level induced by TMZ was not clearly enhanced in the combined treatment regime. Also, we did not observe an attenuation of TMZ-induced autophagy, which is considered a survival mechanism. However, we observed a significant effect of ART on homologous recombination (HR) with downregulation of RAD51 protein expression and HR activity. Further, we found that ART is able to inhibit senescence induced by TMZ. Since HR and senescence are pro-survival mechanisms, its inhibition by ART appears to be a key node in enhancing the TMZ-induced killing response. Enhancement of the antitumor effect of TMZ by co-administration of ART was also observed in a mouse tumor model. In conclusion, the amelioration of TMZ-induced cell death upon ART co-treatment provides a rational basis for a combination regime of TMZ and ART in glioblastoma therapy.

ATM and p53 combined analysis predicts survival in glioblastoma multiforme patients: A clinicopathologic study

Glioblastoma is one of the most malignant cancers, with a distinguishing dismal prognosis: surgery followed by chemo- and radiotherapy represents the current standard of care, and chemo- and radioresistance underlie disease recurrence and short overall survival of patients suffering from this malignancy. ATM is a kinase activated by autophosphorylation upon DNA doublestrand breaks arising from errors during replication, byproducts of metabolism, chemotherapy or ionizing radiations; TP53 is one of the most popular tumor suppressor, with a preeminent role in DNA damage response and repair. To study the effects of the immunohistochemical expression of p-ATM and p53 in glioblastoma patients, 21 cases were retrospectively examined. In normal brain tissue, p-ATM was expressed only in neurons; conversely, in tumors cells, the protein showed a variable cytoplasmic expression (score: +,++,+++), with being completely undetectable in three cases. Statistical analysis revealed that high p-ATM score (++/+++) strongly correlated to shorter survival (P = 0.022). No difference in overall survival was registered between p53 normally expressed (NE) and overexpressed (OE) glioblastoma patients (P = 0.669). Survival analysis performed on the results from combined assessment of the two proteins showed that patients with NE p53 /low pATM score had longer overall survival than the NE p53/ high pATM score counterpart. Cox-regression analysis confirmed this finding (HR = 0.025; CI 95% = 0.002-0.284; P = 0.003). Our study outlined the immunohistochemical expression of p-ATM/p53 in glioblastomas and provided data on their possible prognostic/predictive of response role. A "non-oncogene addiction" to ATM for NEp53 glioblastoma could be postulated, strengthening the rationale for development of ATM inhibiting drugs.

A systematic review and meta-analysis of topoisomerase inhibition in pre-clinical glioma models

Malignant glioma is a devastating disease affecting both adults and children with limited treatment strategies. Pre-clinical animal studies are critical to the development and planning of novel treatment designs for human clinical trials. Topoisomerases has been a target of interest in the treatment of high grade gliomas, such as glioblastoma, in the past years. Here we assess pre-clinical glioma literature with the aim to identify predictive variables that favour treatment outcomes from topoisomerase inhibition. Data was extracted from 90 experimental comparisons, this was divided based on available survival (n = 61) and tumor volume (n = 29) data. The meta-analysis revealed that the overall effect of topoisomerase inhibition prolonged survival by a factor of 1.33 (95% CI: 1.23–1.43) and reduced tumor growth by a factor of 3.21 (95% CI: 1.99–5.88), with considerable between-study heterogeneity. Multivariable meta-regression identified glioma model, type of control, route of drug administration and drug of choice to be predictive of improved survival outcome. Publication bias assessment by contour-enhanced funnel plots, Egger’s regression test and trim and fill analysis showed evidence of publication bias in all studies. This study identified multiple study design factors that should be taken into consideration to improve the translation of pre-clinical investigation of topoisomerase inhibition into clinical use.

Hinokitiol suppresses cancer stemness and oncogenicity in glioma stem cells by Nrf2 regulation

PURPOSE

Glioma is one of the lethal malignancies with poor prognosis. In addition, glioma stem cells (GSCs) have been considered as the crucial player that attributed to the tumorigenesis and drug resistance. In the current study, we investigated the therapeutic effect of hinokitiol, a natural bioactive compound of aromatic tropolone, on the characteristics of GSCs and the possible mechanism.

METHODS

U87MG and T98G glioma cells were used to isolate GSCs. CD133 positivity and ALDH1 activity of GSCs following hinokitiol treatment were assessed by flow cytometry analysis. Secondary sphere formation, migration, invasion, and colony-forming assays were performed to examine the self-renewal capacity and oncogenicity in GCS after hinokitiol administration. The expression of Nrf2 was evaluated by RT-PCR and western blot analyses.

RESULTS

We demonstrated that hinokitiol effectively inhibited the CD133 positivity and ALDH1 activity along with the reduced self-renewal, migration, invasion, and colony formation properties of GSCs. In addition, hinokitiol repressed the gene and protein expression of Nrf2, which has been shown to be critical for those GSCs features. Furthermore, we showed that administration of exogenous Nrf2 counteracted the inhibitory effect of hinokitiol on self-renewal and invasiveness of GSCs.

CONCLUSION

These evidences suggest that treatment of hinokitiol significantly attenuates the hallmarks of GSCs due to downregulation of Nrf2 expression. Hence, hinokitiol may serve as a promising agent for the therapy of glioma.

The Effect of Sodium Valproate on the Glioblastoma U87 Cell Line Tumor Development on the Chicken Embryo Chorioallantoic Membrane and on EZH2 and p53 Expression

Literature data support evidences that glioblastoma (GBM) patients experience prolonged survival due to sodium valproate (NaVP) treatment. The study assessed the human GBM cell U87 xenograft studied in the chicken embryo chorioallantoic membrane (CAM) model evaluating NaVP effect on tumor. Three groups of tumors (each n = 10) were studied: nontreated, treated with 4 mM, and treated with 8 mM of NaVP. The majority of tumors without NaVP treatment during tumor growth destroyed the chorionic epithelium, invaded the mesenchyme, and induced angiogenesis. Incidence of tumor formation on CAM without invasion into the mesenchyme was higher when U87 cells were treated with NaVP; the effect significantly increased with NaVP concentration. Treatment with 8 mM of NaVP did not show clear dynamics of tumor growth during 5 days; at the same time, the angiogenesis failed. With a strong staining of EZH2, p53 in tumors without NaVP treatment was found, and NaVP significantly decreased the expression of EZH2- and p53-positive cells; the effect was significantly higher at its 8 mM concentration. NaVP has a function in blocking the growth, invasion, and angiogenesis of tumor in the CAM model; tumor growth interferes with EZH2 and p53 molecular pathways, supporting the NaVP potential in GBM therapy.

Relationship Between Cytogenetic Complexity and Peritumoral Edema in High-Grade Astrocytoma

BACKGROUND

The purpose of the study is to reveal the association of cytogenetic compltyexi and peritumoral edema volume (PTEV) and its prognostic significance in high-grade astrocytoma patients by culturing patient tumor cells.

METHODS

Twenty-seven high-grade astrocytoma patients were divided into three groups according to karyotype complexity: normal, non-complex karyotype (NCK), and complex karyotype (CK). Endothelial growth factor receptor (EGFR) amplification was detected by FISH, and its association with chromosome 7 abnormalities was analyzed. Mean PTEV of each group was compared by ANOVA to evaluate the relationship between PTEV and cytogenetic complexity.

RESULTS

The PTEV of patients in normal (n=6), NCK (n=8), and CK (n=13) groups were 24.52±17.73, 34.26±35.04, and 86.31±48.7 cm³, respectively (P=0.005). Ten out of 11 patients with EGFR amplification showed abnormalities in chromosome 7. The mean PTEV of EGFR-amplified and non-amplified groups were 80.4±53.7 and 41.3±37.9 cm³, respectively (P=0.035). The average survival of patients with PTEV less than 90 cm³ was 30.52±26.11 months, while in patients with PTEVs over or equal to 90 cm³, it was 10.83±5.53 months (P=0.007).

CONCLUSIONS

The results show an association of complex karyotype with the PTEV of high-grade astrocytoma. EGFR amplification plays a significant role in the formation of peritumoral edema, causing PTEV to increase, which is related with survival. This implies that cytogenetic karyotype can be applied as a prognostic factor.

Manganese superoxide dismutase (MnSOD) is a malignant astrocytoma specific biomarker and associated with adverse prognosis in p53 expressing glioblastoma

BACKGROUND

Manganese super oxide dismutase (MnSOD) has been previously identified as one of the top regulated genes associated with poor survival in glioblastoma (GBM) patients. In the current study we have evaluated the protein expression of MnSOD across various grades of astrocytoma, studied its influence on survival of GBM patients and following recurrence.

METHODS

The protein expression of MnSOD was analyzed on tumor tissue sections by immunohistochemistry on 30 diffuse astrocytomas (DA), 50 anaplastic astrocytomas (AA), 30 paired (primary and recurrent) GBM samples and 30 non-tumor brain tissues. The protein expression among the different grades of diffusely infiltrating astrocytoma (DIA) was evaluated by Kruskal-Wallis one-way ANOVA followed by post hoc test. Wilcoxon matched pair test was employed to assess MnSOD protein expression across 30 paired GBM samples (primary and recurrent). The prognostic impact of MnSOD protein expression individually and following stratification with p53 expression was evaluated in a cohort of 123 GBM patients. Both over-all survival (OS) and progression free survival (PFS) analysis were performed by employing Cox regression analysis and Kaplan-Meier survival analysis on GBM patients.

RESULTS

A significantly increased protein expression of MnSOD was observed among malignant astrocytomas (GBM and AA) in comparison with either DA or non-tumor brain tissues (p<0.05). Among the GBM cases it was noted that the IDH1 immunopositive tumors (R132H mutant protein; n=17) had a low MnSOD expression as opposed to IDH1 immunonegative tumors (n=106), which had high expression of MnSOD (p=0.0307). Further, a statistically significant increase (p=0.010) in extent of MnSOD protein expression was also noted in GBM tumors following recurrence. Protein expression of MnSOD was associated with both poor OS (HR: 1.021; p=0.011) and early PFS (HR: 1.022; p=0.006) on univariate analysis. Multivariate Cox regression analysis as well as Kaplan-Meier survival analysis demonstrated similar poor prognostic association. Stratification of GBM cases based on p53 expression status revealed a strong association of MnSOD with OS (HR: 1.042; p=0.002) and PFS (HR: 1.044; p=0.001) in p53 positive tumor tissue samples. Similar findings were noted on multivariate Cox regression analysis and K-M survival analysis, while no such association was noted in tumor tissues staining negative for p53 expression.

CONCLUSIONS

Our study shows an increased expression of MnSOD in anaplastic astrocytoma and GBM compared to low grade astrocytoma and control brain. An increase in MnSOD expression following GBM tumor recurrence strengthens its putative role in tumor aggressiveness. Further, MnSOD emerges as a poor prognostic biomarker in p53 expressing GBMs, rendering this molecule as a potential therapeutic target in such patients.

The Added Prognostic Value of Preoperative Dynamic Contrast-Enhanced MRI Histogram Analysis in Patients with Glioblastoma: Analysis of Overall and Progression-Free Survival

BACKGROUND AND PURPOSE

The prognostic value of dynamic contrast-enhanced MR imaging in patients with glioblastoma is controversial. We investigated the added prognostic value of dynamic contrast-enhanced MR imaging to clinical parameters and molecular biomarkers in patients with glioblastoma by using histogram analysis.

MATERIALS AND METHODS

This retrospective study consisted of 61 patients who underwent preoperative dynamic contrast-enhanced MR imaging for glioblastoma. The histogram parameters of dynamic contrast-enhanced MR imaging, including volume transfer constant, extravascular extracellular volume fraction, and plasma volume fraction, were calculated from entire enhancing tumors. Univariate analyses for overall survival and progression-free survival were performed with preoperative clinical and dynamic contrast-enhanced MR imaging parameters and postoperative molecular biomarkers. Multivariate Cox regression was performed to build pre- and postoperative models for overall survival and progression-free survival. The performance of models was assessed by calculating the Harrell concordance index.

RESULTS

In univariate analysis, patients with higher volume transfer constant and extravascular extracellular volume fraction values showed worse overall survival and progression-free survival, whereas plasma volume fraction showed no significant correlation. In multivariate analyses for overall survival, the fifth percentile value of volume transfer constant and kurtosis of extravascular extracellular volume fraction were independently prognostic in the preoperative model, and kurtosis of volume transfer constant and extravascular extracellular volume fraction were independently prognostic in the postoperative model. For progression-free survival, independent prognostic factors were minimum and fifth percentile values of volume transfer constant and kurtosis of extravascular extracellular volume fraction in the preoperative model and kurtosis of extravascular extracellular volume fraction in the postoperative model. The performance of preoperative models for progression-free survival was significantly improved when minimum or fifth percentile values of volume transfer constant and kurtosis of extravascular extracellular volume fraction were added.

CONCLUSIONS

Higher volume transfer constant and extravascular extracellular volume fraction values are associated with worse prognosis, and dynamic contrast-enhanced MR imaging may have added prognostic value in combination with preoperative clinical parameters, especially in predicting progression-free survival.

Modern brain tumor imaging

The imaging and clinical management of patients with brain tumor continue to evolve over time and now heavily rely on physiologic imaging in addition to high-resolution structural imaging. Imaging remains a powerful noninvasive tool to positively impact the management of patients with brain tumor. This article provides an overview of the current state-of-the art clinical brain tumor imaging. In this review, we discuss general magnetic resonance (MR) imaging methods and their application to the diagnosis of, treatment planning and navigation, and disease monitoring in patients with brain tumor. We review the strengths, limitations, and pitfalls of structural imaging, diffusion-weighted imaging techniques, MR spectroscopy, perfusion imaging, positron emission tomography/MR, and functional imaging. Overall this review provides a basis for understudying the role of modern imaging in the care of brain tumor patients.

Identification of differential splicing genes in gliomas using exon expression profiling

Diffuse gliomas are the most common type of malignant primary brain tumor, and their initiation and/or progression are often associated with alternative splicing. They produce an enormous economic burden on society and greatly impair the quality of life of those affected. The aim of the current study was to explore the differentially expressed genes (DEGs) observed in glioblastoma (GBM) and oligodendroglioma (OD) at the splicing level, and to analyze their functions in order to identify the underlying molecular mechanisms of gliomas. The exon‑level expression profile data GSE9385 was downloaded from the Gene Expression Omnibus database, and included 26 GBM samples, 22 OD samples and 6 control brain samples. The differentially expressed exon‑level probes were analyzed using the microarray detection of alternative splicing algorithm combined with the splicing index method, and the corresponding DEGs were identified. Next, a Gene Ontology enrichment analysis of the DEGs was performed. Additionally, the protein‑protein interaction (PPI) networks were constructed based on the depth‑first search algorithm. A total of 300 DEGs were identified to be shared by GBM and OD, including 97 upregulated and 203 downregulated DEGs. Furthermore, screening with a defined threshold identified 6 genes that were highly expressed in GBM, including AFF2, CACNA2D3 and ARPP21, while the 6 highly expressed genes in OD notably included CNTN2. The TP53 and HIST1H3A genes were the hub nodes in the PPI network of DEGs from GBM, while CNTN2 was linked to the highest degree in the OD PPI network. The present study provides a comprehensive bioinformatics analysis of DEGs in GBM and OD, which may provide a basis for understanding the initiation and/or progression of glioma development.

Case comparison and literature review of glioblastoma: A tale of two tumors

Background:

Diagnosis of glioblastoma multiforme (GBM) includes a heterogeneous group of tumors. We describe two cases with histopathologically and molecularly similar tumors, but very different outcomes. We attempt to illustrate the need for improved prognostic markers for GBM.

Case Description:

Two patients with similar molecular profiles were retrospectively identified. The following markers were assessed: O⁶-methylguanine DNA methyltransferase (MGMT) methylation, isocitrate dehydrogenase (IDH) 1 and 2 status, epidermal growth factor receptor (EGFR) amplification, phosphatase and tensin homolog (PTEN) status, Ki-67, p53, and 1p/19q status. Each patient was assigned a Karnofsky performance score at presentation. Case 1 (62-year-old male) was a right temporal lobe glioblastoma with a molecular profile of amplified EGFR, normal PTEN, no IDH1/2 mutation, 28.7% MGMT promoter methylation, 5-20% Ki-67, 1p deletion, and 19q intact. The patient underwent resection followed by radiation therapy and 2 years of chemotherapy, and was asymptomatic and tumor free 5 years post diagnosis. Tumor eventually recurred and the patient expired 72 months after initial diagnosis. Case 2 (63-year-old male) was a right frontal white matter mass consistent with glioblastoma with a molecular profile of amplified EGFR, absent PTEN, no IDH1/2 mutation, 9.9% MGMT promoter methylation, 5-10% Ki-67, and 1p/19q status inconclusive. A radical subtotal resection was performed; however, 2 weeks later symptoms had returned. Subsequent imaging revealed a tumor larger than at diagnosis. The patient expired 3 months after initial diagnosis.

Conclusion:

The need for formulating more robust means to classify GBM tumor subtypes is paramount. Standard histopathologic and molecular analyses are costly and did not provide either of these patients with a realistic appraisal of their prognosis. Individualized whole genome testing similar to that being reported for medulloblastoma and other tumors may be preferable to the array of tests as currently utilized.

Connection between Cell Phone use, p53 Gene Expression in Different Zones of Glioblastoma Multiforme and Survival Prognoses

The aim of this paper is to investigate p53 gene expression in the central and peripheral zones of glioblastoma multiforme using a real-time reverse transcription polymerase chain reaction (RT-PCR) technique in patients who use cell phones ≥3 hours a day and determine its relationship to clinicopathological findings and overall survival. Sixty-three patients (38 males and 25 females), diagnosed with glioblastoma multiforme (GBM), underwent tumor resection between 2008 and 2011. Patient ages ranged from 25 to 88 years, with a mean age of 55. The levels of expression of p53 in the central and peripheral zone of the GBM were quantified by RT-PCR. Data on p53 gene expression from the central and peripheral zone, the related malignancy and the clinicopatholagical findings (age, gender, tumor location and size), as well as overall survival, were analyzed. Forty-one out of 63 patients (65%) with the highest level of cell phone use (≥3 hours/day) had higher mutant type p53 expression in the peripheral zone of the glioblastoma; the difference was statistically significant (P=0.034). Results from the present study on the use of mobile phones for ≥3 hours a day show a consistent pattern of increased risk for the mutant type of p53 gene expression in the peripheral zone of the glioblastoma, and that this increase was significantly correlated with shorter overall survival time. The risk was not higher for ipsilateral exposure. We found that the mutant type of p53 gene expression in the peripheral zone of the glioblastoma was increased in 65% of patients using cell phones ≥3 hours a day.

Clinicopathologic characteristics of brain tumors are associated with the presence and patterns of TP53 mutations: evidence from the IARC TP53 Database

Biological diversity in the development and progression of brain tumors may be based on the consequences of the nature of the TP53 mutation in the cancer sample. This study was designed to estimate the possible impact of the presence and spectrum of TP53 mutations on clinical variability of brain tumors using the IARC TP53 Database (R17). Somatic and germline mutation patterns differ in brain tumor carriers. The most frequent mutation in sporadic brain tumors is mutation R273C, which is relatively rare in grade 4 tumors compared with lower-grade tumors (p = 1.2 × 10(-5), OR 0.43, 95% CI 0.29-0.63). Mutations at all hot spots, DNA contact mutations, and mutations in the conserved regions of the TP53 gene are also more common in grade 1-3 tumors than in grade 4 tumors. The frequencies of missense mutations at hotspot codons and DNA contact mutations gradually decrease in all three age groups studied, indicating the role of these mutations in early-onset tumors. The role of TP53 somatic mutations in the development of brain tumors has been elucidated in the individual-participant meta-analysis that provided, for the first time, strong evidence that mean age at the onset of sporadic brain tumor is significantly lower in patients with mutated compared with wild-type TP53 in all groups stratified by tumor grade. The presence and patterns of TP53 mutations are associated mainly with the age at the onset and with the development of less malignant brain tumors. Malignant degeneration of brain tumors may depend on other genetic determinants.

ASYMMETRIC CELL DIVISION: IMPLICATIONS FOR GLIOMA DEVELOPMENT AND TREATMENT

Glioma is a heterogeneous disease process with differential histology and treatment response. It was previously thought that the histological features of glial tumors indicated their cell of origin. However, the discovery of continuous neuro-gliogenesis in the normal adult brain and the identification of brain tumor stem cells within glioma have led to the hypothesis that these brain tumors originate from multipotent neural stem or progenitor cells, which primarily divide asymmetrically during the postnatal period. Asymmetric cell division allows these cell types to concurrently self-renew whilst also producing cells for the differentiation pathway. It has recently been shown that increased symmetrical cell division, favoring the self-renewal pathway, leads to oligodendroglioma formation from oligodendrocyte progenitor cells. In contrast, there is some evidence that asymmetric cell division maintenance in tumor stem-like cells within astrocytoma may lead to acquisition of treatment resistance. Therefore cell division mode in normal brain stem and progenitor cells may play a role in setting tumorigenic potential and the type of tumor formed. Moreover, heterogeneous tumor cell populations and their respective cell division mode may confer differential sensitivity to therapy. This review aims to shed light on the controllers of cell division mode which may be therapeutically targeted to prevent glioma formation and improve treatment response.

Integrins and p53 pathways in glioblastoma resistance to temozolomide

Glioblastoma is the most common malignant primary brain tumor. Surgical resection, postoperative radiotherapy plus concomitant and adjuvant chemotherapy with temozolomide (TMZ) is the standard of care for newly diagnosed glioblastoma. In the past decade, efforts have been made to decipher genomic and core pathway alterations to identify clinically relevant glioblastoma subtypes. Based on these studies and more academic explorations, new potential therapeutic targets were found and several targeting agents were developed. Such molecules should hopefully overcome the resistance of glioblastoma to the current therapy. One of the hallmarks of glioblastoma subtypes was the enrichment of extracellular matrix/invasion-related genes. Integrins, which are cell adhesion molecules important in glioma cell migration/invasion and angiogenesis were one of those genes. Integrins seem to be pertinent therapeutic targets and antagonists recently reached the clinic. Although the p53 pathway appears often altered in glioblastoma, conflicting results can be found in the literature about the clinically relevant impact of the p53 status in the resistance to TMZ. Here, we will summarize the current knowledge on (1) integrin expression, (2) p53 status, and (3) relationship between integrins and p53 to discuss their potential impact on the resistance of glioblastoma to temozolomide.

Clinicopathological features and molecular analysis of primary glioblastomas in Moroccan patients

Glioblastoma is the most frequent and most aggressive primary brain tumor. Primary and secondary glioblastomas develop through different genetic pathways. The aim of this study was to determinate the genetic and clinical features of primary glioblastoma in Moroccan patients. The blood and tumor samples were obtained from a group of 34 Moroccan patients affected with primary glioblastoma. The tumors were investigated for TP53, IDH1, and IDH2 mutations using PCR sequencing analysis. Clinicopathological data showed that the mean age at diagnosis of patients was 50.06 years, the sex ratio was 11 F/23 M, and the median of Karnofsky performance score was 60. About 18 % of patients were initially treated by total tumor resection, 41 % by subtotal, and 38 % by partial resection, but biopsy was performed for a single patient (3 %). Twenty-five patients (74 %) received radiotherapy. In addition, the median survival of the all patients was 13 months following diagnosis. There was a significant impact of higher Karnofsky performance score (KPS) (≥80) on overall survival, p-log-rank test = 0.0002, whereas other parameters did not show any significant differences. The molecular analysis revealed TP53 mutations in 3/34 (8.82 %) cases; R273H, R306X, and Q136X. However, none of the analyzed samples contained the R132-IDH1 or R172-IDH2 mutations. These results showed the absence of IDH1 mutation in primary glioblastoma, confirming that this mutation is a hallmark of secondary glioblastoma. It can be used to distinguish primary from secondary glioblastomas. We found also that higher KPS was a significantly favorable factor in patients with primary glioblastoma.

Detailed characterization of alterations of chromosomes 7, 9, and 10 in glioblastomas as assessed by single-nucleotide polymorphism arrays

Glioblastomas are cytogenetically heterogeneous tumors that frequently display alterations of chromosomes 7, 9p, and 10q. We used high-density (500K) single-nucleotide polymorphism arrays to investigate genome-wide copy number alterations and loss of heterozygosity in 35 primary glioblastomas. We focused on the identification and detailed characterization of alterations involving the most frequently altered chromosomes (chromosomes 7, 9, and 10), the identification of distinct prognostic subgroups of glioblastomas based on the cytogenetic patterns of alteration for these chromosomes, and validation of their prognostic impact in a larger series of tumors from public databases. Gains of chromosome 7 (97%), with or without epidermal growth factor receptor (EGFR) amplification, and losses of chromosomes 9p (83%) and 10 (91%) were the most frequent alterations. Such alterations defined five different cytogenetic groups with a significant effect on patient survival; notably, EGFR amplification (29%) was associated with a better survival among older patients, as confirmed by multivariate analysis of a larger series of glioblastomas from the literature. In addition, our results provide further evidence about the relevance of other genes (eg, EGFR, CDKN2A/B, MTAP) in the pathogenesis of glioblastomas. Altogether, our results confirm the cytogenetic heterogeneity of glioblastomas and suggest that their stratification based on combined assessment of cytogenetic alterations involving chromosomes 7, 9, and 10 may contribute to the prognostic evaluation of glioblastomas.

Modeling Adult Gliomas Using RCAS/t-va Technology

Malignant gliomas remain the most devastating childhood and adult tumors of the central nervous system. Although adult and pediatric gliomas are histologically indistinguishable, they differ in location, behavior, and molecular characteristics. This implies that the molecular pathways and pathophysiology of malignant gliomagenesis in these two populations are distinct. Such differences between adult and pediatric gliomas may predict different therapeutic responses. Therefore, accurate genetically engineered models of adult and pediatric gliomas may help understand the biology of these tumors and evaluate therapeutic agents in preclinical studies. It has been proposed that gliomas arise from the subventricular zone in mice during development. Here, we demonstrate that, in adult mice, gliomas may arise not only when injected in the subventricular zone but also when injected in the cortex and cerebellum. Our work demonstrates a versatile and highly reproducible adult mouse model of glioma, which can be easily incorporated into preclinical studies.

Thymoquinone induces telomere shortening, DNA damage and apoptosis in human glioblastoma cells

Background

A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells.

Methodology/Principal Findings

The cytotoxic effect of thymoquinone, a component derived from the plant Nigella sativa, was tested on human glioblastoma and normal cells. Our findings demonstrated that glioblastoma cells were more sensitive to thymoquinone-induced antiproliferative effects. Thymoquinone induced DNA damage, cell cycle arrest and apoptosis in the glioblastoma cells. It was also observed that thymoquinone facilitated telomere attrition by inhibiting the activity of telomerase. In addition to these, we investigated the role of DNA-PKcs on thymoquinone mediated changes in telomere length. Telomeres in glioblastoma cells with DNA-PKcs were more sensitive to thymoquinone mediated effects as compared to those cells deficient in DNA-PKcs.

Conclusions/Significance

Our results indicate that thymoquinone induces DNA damage, telomere attrition by inhibiting telomerase and cell death in glioblastoma cells. Telomere shortening was found to be dependent on the status of DNA-PKcs. Collectively, these data suggest that thymoquinone could be useful as a potential chemotherapeutic agent in the management for brain tumours.

Pseudoprogression in patients with malignant gliomas treated with concurrent temozolomide and radiotherapy: potential role of p53

We investigated pseudoprogression (psPD) in patients with malignant gliomas treated with radiotherapy (RT) and maintenance temozolomide (TMZ) in terms of incidence, outcomes, and predictive and prognostic factors. We evaluated p53 overexpression by immunohistochemical analysis of thirty-five tumor samples as a predictor for psPD. The time to progression and overall survival were compared between subgroups, psPD versus early progression (ePD) versus nonprogression (nonPD). Eight patients developed psPD among eighteen patients with lesion enlargement at the first MRI scan, and the others were classified as ePD. The remaining stable or improved patients were classified as nonPD. All patients with psPD were alive at last follow-up (median follow-up period was 12 months; range 5.8-58.5 months). Overall survival of psPD patients was significantly higher than ePD patients (P < 0.01). There was no significant survival difference between the psPD group and nonPD group (P = 0.25). Seven (87.5%) of eight tumors with psPD showed p53 overexpression, as compared to 3 (30%) of the ten tumors with ePD (P = 0.03). Our study indicates that psPD following chemoradiotherapy with TMZ is associated with significantly better overall survival compared to that of ePD, and is comparable to nonPD group. Overexpression of p53 was identified as a potential biomarker for predicting the development of psPD.

The pathobiology of glioma tumors

The ongoing characterization of the genetic and epigenetic alterations in the gliomas has already improved the classification of these heterogeneous tumors and enabled the development of rodent models for analysis of the molecular pathways underlying their proliferative and invasive behavior. Effective application of the targeted therapies that are now in development will depend on pathologists' ability to provide accurate information regarding the genetic alterations and the expression of key receptors and ligands in the tumors. Here we review the mechanisms that have been implicated in the pathogenesis of the gliomas and provide examples of the cooperative nature of the pathways involved, which may influence the initial therapeutic response and the potential for development of resistance.

The use of hsa-miR-21, hsa-miR-181b and hsa-miR-106a as prognostic indicators of astrocytoma

BACKGROUND

The aberrant expression of microRNAs (miRNAs) is associated with a variety of diseases including cancers. In the present study, the miRNA expression profile was examined in astrocytoma, a malignant and prevalent intracranial tumour in adults.

METHODS

We screened the expression profile of 200 miRNAs in a training sample set consisting of 84 astrocytoma samples and 20 normal adjacent tissue (NAT) samples using the method of stem-loop quantitative RT-PCR. The significantly altered miRNAs were validated in another independent sample set consisting of 40 astrocytoma samples and 40 NAT samples. The correlation of the miRNA levels with survival in astrocytoma samples was estimated by performing Kaplan-Meier survival analysis and univariate/multivariate Cox proportional hazard regression analysis.

RESULTS

After a two-phase selection and validation process, seven miRNAs were found to have a significantly different expression profile in astrocytoma samples upon comparison to the NAT samples. Unsupervised clustering analysis further revealed the great potential of the 7-miRNA profile to differentiate between tumours and normal brain tissues. The down-regulation of hsa-miR-137 in astrocytomas was shown to be associated with advanced clinical stages of this disease. Using Kaplan-Meier survival analysis we showed that low expression of hsa-miR-181b or hsa-miR-106a, or high expression of hsa-miR-21 was significantly associated with poor patient survival. Moreover, Cox proportional hazard regression analysis revealed that this prognostic impact was independent of other clinicopathological factors.

CONCLUSIONS

Our results suggest a great potential for the use of miRNA profiling as a powerful diagnostic and prognostic marker in defining the signature of astrocytomas and in predicting the post-surgical outcome.

Decreased expression of germinal center-associated nuclear protein is involved in chromosomal instability in malignant gliomas

Malignant glioma (MG) is highly proliferative and invasive, with the malignant characteristics associated with aneuploidy and chromosomal instability (CIN). Here, we found that the level of germinal center-associated nuclear protein (GANP), a mammalian homologue of yeast Sac3, was markedly decreased in MGs with a poor prognosis; and thus we explored the effect of its decrease on cell-cycle progression of MG cell lines. Glioblastomas showed a significantly lower level of ganp mRNA than anaplastic astrocytomas, as measured by real-time reverse transcription-PCR, in 101 cases of adult MG. MGs of ganp(Low) expression displayed more malignant characteristics, with loss of heterozygosity on chromosome 10, epidermal growth factor receptor gene amplification, and significantly poorer prognosis than the ganp(High) group. Human diploid fibroblasts depleted of ganp mRNA by the RNA interference (RNAi) method showed a decreased percentage of S-phase cells and a cellular-senescence phenotype. MG cell lines harboring abnormalities of various cell-cycle checkpoint molecules displayed slippage of mitotic checkpoints and an increased proportion of hyperploid cells after ganp RNAi-treatment. These results suggest that GANP protects cells from cellular senescence caused by DNA damage and that a significant decrease in GANP expression leads to malignancy by generating hyperploidy and CIN.

Long-term survivors of glioblastoma: clinical features and molecular analysis

BACKGROUND

Glioblastoma is a highly lethal neoplasm with a median survival of 12-14 months; only 2-5% of patients survive >3 years.

METHODS

At our institute, patients with glioblastoma are initially treated with maximum tumor resection followed by radiation and the intravenous injection of nimustine hydrochloride (ACNU).

RESULTS

Using this strategy, 18 of 123 (14.6%) patients treated at our hospital survived >3 years; 7 manifested no recurrence, and the other 11 had early recurrence and received additional therapies. To identify factors associated with prolonged survival, we compared these patients with 21 short-term (<1.5 years) glioblastoma survivors. In the long-term survivors, the MGMT promoter methylation was significantly more frequent. The rate of p53 mutation was lower, and the rate of PTEN mutations and the proliferation index were slightly higher in short-term survivors.

CONCLUSION

By multivariate analysis, we found that a younger age and MGMT promoter methylation were significant favorable factors in patients with glioblastoma.

Prognostic and predictive value of p53 in low MGMT expressing glioblastoma treated with surgery, radiation and adjuvant temozolomide chemotherapy

OBJECTIVE

To assess the prognostic and predictive significance of p53 protein expression in low O6-methylguanine-DNA methyltransferase (MGMT) expressing glioblastoma multiform (GBM) treated with combined therapy.

METHODS

The authors reviewed the clinical outcomes of 46 low MGMT expressing GBM patients who had undergone surgery, conventional local radiotherapy and temozolomide chemotherapy. Correlation between p53 expression level and clinical outcomes were analysed with univariate and multivariate Cox model.

RESULTS

Patients with low p53 expression had a significantly improved progression free survival (PFS) (p=0.015) and overall survival (OS) (p=0.047) compared to those with high expression. On both univariate and multivariate analyses, low p53 expression persisted as a significant independent favorable prognostic factor for PFS (p=0.017). Pre-operative Karnofsky performance status score (p=0.029), tumor resection extent (p=0.045) and p53 expression level (p=0.038) were significant independent prognostic factors for OS.

CONCLUSION

In these low MGMT expressing GBM patients with combined treatment, low p53 expression was a significant independent favorable prognostic factor for both PFS and OS. In addition to MGMT, p53 may be another stratification variable in the future therapeutic trials.

Antitumor effect of humanized anti–interleukin-6 receptor antibody (tocilizumab) on glioma cell proliferation

Object

Interleukin-6 (IL-6) is a pleiotropic cytokine that regulates diverse physiological functions, including cell proliferation and survival. Recent studies have shown that IL-6 expression is often elevated in response to several types of glioma. Although IL-6 is said to play an important role in glioma, the involvement of IL-6 signaling has been quite controversial. The aim of this study was to evaluate the involvement of IL-6 signaling in glioma and the inhibitory effect of IL-6 signaling on glioma tumor proliferation.

Methods

The expression of IL-6 receptors (IL-6Rs) was evaluated in glioma tissues by means of immunohistochemical analysis, and the involvement of IL-6 signaling in glioblastoma multiforme (GBM) U87MG cell proliferation was also determined. In addition, to examine the inhibitory effect of IL-6 signaling on glioma cell proliferation, the authors investigated the effects of tocilizumab, the humanized anti–human IL-6R antibody in U87MG cells.

Results

Increased immunoreactivity for IL-6R was predominantly found in the cytoplasm of endothelial cells in all GBM samples. Inhibition of IL-6 signaling by both IL-6– and IL-6R–specific small interfering RNA and AG490, a specific inhibitor of JAK2 phosphorylation, suppressed glioma cell proliferation. Furthermore, tocilizumab, a clinically developed humanized anti–human IL-6R antibody, exerted an antiproliferative effect on cells from the GBM cell line U87MG via the IL-6R–dependent JAK-STAT3 pathway.

Conclusions

The IL-6 signaling pathway plays an important role in glioma cell proliferation, and tocilizumab exerts an antitumor effect in U87MG glioma cells. These results may bring new insight into the molecular pathogenesis of glioma and may lead to a new therapeutic intervention.

Single nucleotide polymorphism 309 affects murin-double-minute 2 protein expression but not glioma tumorigenesis

Murin-double-minute 2 (MDM2) is an important negative regulator of the p53 tumor suppressor, and affects the p53 protein level and transcriptional activity. The genotype of the single nucleotide polymorphism in the promoter region of MDM2 (single nucleotide polymorphism [SNP] 309) is associated with the MDM2 protein expression level and the onset age of several types of cancer. The SNP309 genotype was investigated in 254 Japanese patients with glioma and 50 healthy subjects. The genotype frequency of SNP309 was T/T homozygous in 62 patients (24%), T/G heterozygous in 126 (50%), and G/G homozygous in 66 (26%) of the glioma patients, and was similar in the healthy subjects. The G/G ratio was higher in our Japanese subjects than in Western populations. Immunohistochemical study of glioma tissues showed that the G/G genotype was associated with higher expression of MDM2 protein compared to the T/T genotype, suggesting that SNP309 attenuates MDM2 protein expression in vivo. However, no association was found between the SNP309 genotype and the histological grade of glioma, age at disease onset, or p53 gene mutation rate. In our study population, SNP309 affected MDM2 protein level, but had no significant involvement in glioma tumorigenesis.

Association of mutant TP53 with alternative lengthening of telomeres and favorable prognosis in glioma

The molecular basis for alternative lengthening of telomeres (ALT), a prognostic marker for glioma patients, remains unknown. We examined TP53 status in relation to telomere maintenance mechanism (TMM) in 108 patients with glioblastoma multiforme and two patients with anaplastic astrocytoma from New Zealand and United Kingdom. Tumor samples were analyzed with respect to telomerase activity, telomere length, and ALT-associated promyelocytic leukemia nuclear bodies to determine their TMM. TP53 mutation was analyzed by direct sequencing of coding exons 2 to 11. We found an association between TP53 mutation and ALT mechanism and between wild-type TP53 and telomerase and absence of a known TMM (P < 0.0001). We suggest that TP53 deficiency plays a permissive role in the activation of ALT.

Delivery systems and molecular targets of mechanism-based therapies for GBM

Glioblastoma multiforme (GBM) is the most common malignant brain tumor of adults and is in great need of novel diagnostic and therapeutic approaches. Diagnosis is beginning to consider a tumor's genetic status and in the future may incorporate gene expression or proteomic profiles. Genetic alterations in gliomas that are being used in classification include TP53 and retinoblastoma pathway disruption, PTEN mutations, epidermal growth factor receptor amplification and 1p/19q losses. Molecular mechanisms are being exploited to treat glioblastoma multiforme. Tyrosine kinase inhibitors directed at epidermal growth factor receptor (ZD1839, OSI-774) are being explored. Farnesyltransferase inhibitors (R115777) block activation of the ras pathway and may be effective. Antagonists of the endothelin receptor (e.g., atrasentan) expressed on blood vessels may block the high degree of angiogenesis in gliomas. Tumors lacking methylthioadenosine phosphorylase are sensitive to inhibitors of de novo adenosine synthesis (SDX-102) since they lack a salvage pathway. Future goals are to tailor therapies to a tumor's molecular, proteomic or genomic status ,and manage glioblastoma multiformes as in chronic diseases in a multidisciplinary clinical setting.

Survival prediction in patients with glioblastoma multiforme by human telomerase genetic variation

PURPOSE

Glioblastoma multiforme (GBM) is the most common and aggressive glioma with the poorest survival. Use of biomarkers for screening patients with GBM may be used to modify treatments and improve outcomes. The level of human telomerase (hTERT) expression is an independent predictor of outcome of many cancers, and a functional variant of hTERT MNS16A (shorter tandem repeats or short [S] allele) is associated with increased hTERT mRNA expression. We investigated whether hTERT MNS16A variant genotype predicted survival in GBM patients.

PATIENTS AND METHODS

We genotyped hTERT MNS16A in 299 GBM patients using polymerase chain reaction and determined hTERT genotype by classifying the DNA band of 243 or 272 base pairs (bp) as S allele and 302 or 333 bp as long (L) allele. We compared overall survival using Kaplan-Meier estimates and equality of survival distributions using the log-rank test, and we computed univariate and multivariate Cox proportional hazards models to estimate the effects of selected variables.

RESULTS

Overall survival differed significantly by hTERT MNS16A genotype, with median survivals of 25.1, 14.7, and 14.6 months for the SS, SL, and LL genotypes, respectively. Compared with the SS genotype, the hazard ratios for the SL and LL genotypes were 1.69 and 1.87, respectively, after adjustment for other factors. Multivariate Cox regression analysis showed an independent statistically significant association between the hTERT MNS16A variant genotype and outcome.

CONCLUSION

A functional hTERT MNS16A genotype is a potential biomarker for assessment of survival outcome of GBM. Larger studies are needed to verify these findings.

Glioma: What is the role of c-Myc, hsp90 and telomerase?

The continuous advancements in cancer research have contributed to the overwhelming evidence of the presence of telomerase in primary and secondary tumours together with hsp90 and c-Myc. This review will discuss the important role of telomerase together with hsp90 and c-Myc within the initiation and progression of gliomas. Also it will review the differential expression of these genes in the different grades of gliomas and the possibility of new treatments targeting these specific genes.