IDH1 and IDH2 mutations in gliomas

The generation of glioma organoids and the comparison of two culture methods

BACKGROUND

The intra- and inter-tumoral heterogeneity of gliomas and the complex tumor microenvironment make accurate treatment of gliomas challenging. At present, research on gliomas mainly relies on cell lines, stem cell tumor spheres, and xenotransplantation models. The similarity between traditional tumor models and patients with glioma is very low.

AIMS

In this study, we aimed to address the limitations of traditional tumor models by generating patient-derived glioma organoids using two methods that summarized the cell diversity, histological features, gene expression, and mutant profiles of their respective parent tumors and assess the feasibility of organoids for personalized treatment.

MATERIALS AND METHODS

We compared the organoids generated using two methods through growth analysis, immunohistological analysis, genetic testing, and the establishment of xenograft models.

RESULTS

Both types of organoids exhibited rapid infiltration when transplanted into the brains of adult immunodeficient mice. However, organoids formed using the microtumor method demonstrated more similar cellular characteristics and tissue structures to the parent tumors. Furthermore, the microtumor method allowed for faster culture times and more convenient operational procedures compared to the Matrigel method.

DISCUSSION

Patient-derived glioma organoids, especially those generated through the microtumor method, present a promising avenue for personalized treatment strategies. Their capacity to faithfully mimic the cellular and molecular characteristics of gliomas provides a valuable platform for elucidating tumor biology and evaluating therapeutic modalities.

CONCLUSION

The success rates of the Matrigel and microtumor methods were 45.5% and 60.5%, respectively. The microtumor method had a higher success rate, shorter establishment time, more convenient passage and cryopreservation methods, better simulation of the cellular and histological characteristics of the parent tumor, and a high genetic guarantee.

LonP1 Drives Proneural Mesenchymal Transition in IDH1-R132H Diffuse Glioma

Malignant astroctyoma and glioblastoma are diffuse CNS tumors that have markedly similar features, including microvascular proliferation and necrosis, and the latter presents higher grade and poorer survival. The Isocitrate dehydrogenase 1/2 (IDH) mutation further predicts improved survival and is present in oligodendroglioma and astrocytoma. The latter are more prevalent in younger populations with a median age of 37 years at diagnosis as compared to glioblastoma with a median age of 641,2. These tumors frequently have co-occurring ATRX and/or TP53 mutations (Brat et al., 2021). The IDH mutation is known to cause dysregulation of the hypoxia response broadly in CNS tumors and subsequent reduction in both tumor growth and treatment resistance. The frequency of tumor recurrence is high for diffuse CNS tumors. Understanding the mechanism and potential molecular targets enhancing treatment resistance and local invasion in IDH mutant diffuse glioma is necessary for developing new treatment strategies for better tumor control and improving overall survival. Recent evidence highlights the importance of local foci in IDH mutant glioma with an accelerated stress response as responsible for recurrence in these tumors. Here, we demonstrate that LonP1 drives NRF2 and subsequent proneural mesenchymal transition interdependent with the IDH mutation in response to stress and other tumor microenvironment cues. Our findings provide further evidence that targeting LonP1 may be a crucial strategy for improving the standard-of-care treatment in IDH mutant diffuse astrocytoma.

Treatments against Polymorphosal discrepancies in Glioblastoma Multiforme

Glioblastoma (GB) are aggressive tumors that obstruct normal brain function. While the skull cannot expand in response to cancer growth, the growing pressure in the brain is generally the first sign. It can produce more frequent headaches, unexplained nausea or vomiting, blurred peripheral vision, double vision, a loss of feeling or movement in an arm or leg, and difficulty speaking and concentrating; all depend on the tumor's location. GB can also cause vascular thrombi, damaging endothelial cells and leading to red blood cell leakage. Latest studies have revealed the role of single nucleotide polymorphisms (SNPs) in developing and spreading cancers such as GB and breast cancer. Many discovered SNPs are associated with GB, particularly in great abundance in the promoter region, creating polygenetic vulnerability to glioma. This study aims to compile a list of some of the most frequent and significant SNPs implicated with GB formation and proliferation.

Radiomic study on preoperative multi-modal magnetic resonance images identifies IDH-mutant TERT promoter-mutant gliomas

OBJECTIVES

Gliomas with comutations of isocitrate dehydrogenase (IDH) genes and telomerase reverse transcriptase (TERT) gene promoter (IDHmut pTERTmut) show distinct biological features and respond to first-line treatment differently in comparison with other gliomas. This study aimed to characterize the IDHmut pTERTmut gliomas in multimodal MRI using the radiomic method and establish a precise diagnostic model identifying this group of gliomas.

METHODS

A total of 140 patients with untreated primary gliomas were admitted between 2016 and 2020 to West China Hospital as a discovery cohort, including 22 IDHmut pTERTmut patients. Thirty-four additional cases from a different hospital were included in the study as an independent validation cohort. A total of 3654 radiomic features were extracted from the preoperative multimodal MRI images (T1c, FLAIR, and ADC maps) and filtered in a data-driven approach. The discovery cohort was split into training and test sets by a 4:1 ratio. A diagnostic model (multilayer perceptron classifier) for detecting the IDHmut pTERTmut gliomas was trained using an automatic machine-learning algorithm named tree-based pipeline optimization tool (TPOT). The most critical radiomic features in the model were identified and visualized.

RESULTS

The model achieved an area under the receiver-operating curve (AUROC) of 0.971 (95% CI, 0.902-1.000), the sensitivity of 0.833 (95% CI, 0.333-1.000), and the specificity of 0.966 (95% CI, 0.931-1.000) in the test set. The area under the precision-recall curve (AUCPR) was 0.754 (95% CI, 0.572-0.833) and the F1 score was 0.833 (95% CI, 0.500-1.000). In the independent validation set, the model reached 0.952 AUROC, 0.714 sensitivity, 0.963 specificity, 0.841 AUCPR, and 0.769 F1 score. MR radiomic features of the IDHmut pTERTmut gliomas represented homogenous low-complexity texture in three modalities.

CONCLUSIONS

An accurate diagnostic model was constructed for detecting IDHmut pTERTmut gliomas using multimodal radiomic features. The most important features were associated with the homogenous simple texture of IDHmut pTERTmut gliomas in MRI images transformed using Laplacian of Gaussian and wavelet filters.

Exosome-based strategies for diagnosis and therapy of glioma cancer

Glioblastoma belongs to the most aggressive type of cancer with a low survival rate that is characterized by the ability in forming a highly immunosuppressive tumor microenvironment. Intercellular communication are created via exosomes in the tumor microenvironment through the transport of various biomolecules. They are primarily involved in tumor growth, differentiation, metastasis, and chemotherapy or radiation resistance. Recently several studies have highlighted the critical role of tumor-derived exosomes against immune cells. According to the structural and functional properties, exosomes could be essential instruments to gain a better molecular mechanism for tumor understanding. Additionally, they are qualified as diagnostic/prognostic markers and therapeutic tools for specific targeting of invasive tumor cells such as glioblastomas. Due to the strong dependency of exosome features on the original cells and their developmental status, it is essential to review their critical modulating molecules, clinical relevance to glioma, and associated signaling pathways. This review is a non-clinical study, as the possible role of exosomes and exosomal microRNAs in glioma cancer are reported. In addition, their content to overcome cancer resistance and their potential as diagnostic biomarkers are analyzed.

A high-throughput screening assay for mutant isocitrate dehydrogenase 1 using acoustic droplet ejection mass spectrometry

Acoustic droplet ejection mass spectrometry (ADE-MS) has recently emerged as a promising label-free, MS-based readout method for high throughput screening (HTS) campaigns in early pharmaceutical drug discovery, since it enables high-speed analysis directly from 384- or 1536-well plates. In this manuscript we describe our characterization of an ADE-MS based high sample content enzymatic assay for mutant isocitrate dehydrogenase 1 (IDH1) R132H with a strong focus on assay development. IDH1 R132H has become a very attractive therapeutic target in the field of antitumor drug discovery, and several pharmaceutical companies have attempted to develop novel small molecule inhibitors against mutant IDH1. With the development of an mIDH1 ADE-MS based HTS assay and a detailed comparison of this new readout technique to the commonly used fluorescence intensity mIDH1 assay, we demonstrated good correlation of both methods and were able to identify new potent inhibitors of mIDH1.

Targeting Wnt/β-Catenin Signaling by TET1/FOXO4 Inhibits Metastatic Spreading and Self-Renewal of Cancer Stem Cells in Gastric Cancer

Simple Summary

Metastasis is the main cause of death for patients suffering gastric cancer. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) are critical attributes of metastasis, both of which are regulated tightly by DNA methylation and Wnt/β-catenin signaling. In this study, we unveiled a novel TET1-FOXO4-β-catenin signaling cascade, in which TET1 inhibits β-catenin activity and its nuclear translocation through transactivating FOXO4 expression. TET1 expression can significantly inhibit EMT and stemness properties of gastric cancer cells, while knocking-down endogenous TET1 induces metastasis and enhances self-renewal of CSCs by activating canonical Wnt signaling, which could be fully rescued by modulating FOXO4 expression. Our data also showed that low expression of TET1 or FOXO4 predicts poor survival of gastric cancer patients, suggesting reactivation of TET1 or FOXO4 might be a novel therapeutic approach to prevent gastric cancer metastasis.

Abstract

Metastasis is the main cause of death for patients suffering gastric cancer. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) are critical attributes of metastasis, both of which are regulated tightly by DNA methylation and Wnt/β-catenin signaling. Here, we studied the functions of DNA dioxygenase TET1 in regulating Wnt signaling and in gastric cancer metastasis. Knocking-down and overexpressing TET1 in gastric cancer cells promoted and inhibited metastatic spreading to the liver in immune-deficient mice, respectively. TET1 showed inhibitory effects on metastasis-related features -EMT and CSC, which were reversed by interfering with Wnt/β-catenin signaling. RNA-sequencing identified FOXO4 as a direct transactivating target of TET1. FOXO4 directly interacted with β-catenin and recruited it in the cytoplasm, so as to inhibit β-catenin-mediated transcription of Wnt target genes, including CSC marker EpCAM. Moreover, modulation of FOXO4 could reverse the effects of TET1 manipulation on EMT and self-renewal of CSCs. The analysis with clinical samples confirmed the value of FOXO4 as an independent prognostic predictor of patients’ overall survival. Taken together, regulation of Wnt signaling by TET1/FOXO4 is essential for metastasis-associated cellular properties, and targeting TET1/FOXO4/β-catenin pathway may serve as promising therapeutics in the prevention and treatment of gastric cancer metastasis.

Preoperative Diagnosis and Molecular Characterization of Gliomas With Liquid Biopsy and Radiogenomics

Gliomas are a heterogenous group of central nervous system tumors with different outcomes and different therapeutic needs. Glioblastoma, the most common subtype in adults, has a very poor prognosis and disabling consequences. The World Health Organization (WHO) classification specifies that the typing and grading of gliomas should include molecular markers. The molecular characterization of gliomas has implications for prognosis, treatment planning, and prediction of treatment response. At present, gliomas are diagnosed via tumor resection or biopsy, which are always invasive and frequently risky methods. In recent years, however, substantial advances have been made in developing different methods for the molecular characterization of tumors through the analysis of products shed in body fluids. Known as liquid biopsies, these analyses can potentially provide diagnostic and prognostic information, guidance on choice of treatment, and real-time information on tumor status. In addition, magnetic resonance imaging (MRI) is another good source of tumor data; radiomics and radiogenomics can link the imaging phenotypes to gene expression patterns and provide insights to tumor biology and underlying molecular signatures. Machine and deep learning and computational techniques can also use quantitative imaging features to non-invasively detect genetic mutations. The key molecular information obtained with liquid biopsies and radiogenomics can be useful not only in the diagnosis of gliomas but can also help predict response to specific treatments and provide guidelines for personalized medicine. In this article, we review the available data on the molecular characterization of gliomas using the non-invasive methods of liquid biopsy and MRI and suggest that these tools could be used in the future for the preoperative diagnosis of gliomas.

Multi-institutional study of the frequency, genomic landscape, and outcome of IDH-mutant glioma in pediatrics

BACKGROUND

The incidence and biology of IDH1/2 mutations in pediatric gliomas are unclear. Notably, current treatment approaches by pediatric and adult providers vary significantly. We describe the frequency and clinical outcomes of IDH1/2-mutant gliomas in pediatrics.

METHODS

We performed a multi-institutional analysis of the frequency of pediatric IDH1/2-mutant gliomas, identified by next-generation sequencing (NGS). In parallel, we retrospectively reviewed pediatric IDH1/2-mutant gliomas, analyzing clinico-genomic features, treatment approaches, and outcomes.

RESULTS

Incidence: Among 851 patients with pediatric glioma who underwent NGS, we identified 78 with IDH1/2 mutations. Among patients 0-9 and 10-21 years old, 2/378 (0.5%) and 76/473 (16.1%) had IDH1/2-mutant tumors, respectively. Frequency of IDH mutations was similar between low-grade glioma (52/570, 9.1%) and high-grade glioma (25/277, 9.0%). Four tumors were graded as intermediate histologically, with one IDH1 mutation. Outcome: Seventy-six patients with IDH1/2-mutant glioma had outcome data available. Eighty-four percent of patients with low-grade glioma (LGG) were managed observantly without additional therapy. For low-grade astrocytoma, 5-year progression-free survival (PFS) was 42.9% (95%CI:20.3-63.8) and, despite excellent short-term overall survival (OS), numerous disease-related deaths after year 10 were reported. Patients with high-grade astrocytoma had a 5-year PFS/OS of 36.8% (95%CI:8.8-66.4) and 84% (95%CI:50.1-95.6), respectively. Patients with oligodendroglioma had excellent OS.

CONCLUSIONS

A subset of pediatric gliomas is driven by IDH1/2 mutations, with a higher rate among adolescents. The majority of patients underwent upfront observant management without adjuvant therapy. Findings suggest that the natural history of pediatric IDH1/2-mutant glioma may be similar to that of adults, though additional studies are needed.

Pediatric Glial Tumors

Pediatric glial tumors are unique from their adult counterparts. This important distinction is recognized and incorporated into the World Health Organization classification of central nervous system tumors and applies to both high- and low-grade gliomas, incorporating their specific molecular profiles. Molecular alterations in pediatric high-grade gliomas provide important prognostic information, for example in H3 K27M-mutant tumors. The integration of molecular information is also important for pediatric low-grade gliomas due to their overlapping morphologies and the prognostic and therapeutic implications of these molecular alterations. In this paper, we cover a variety of glial tumors, encompassing neoplasms with predominantly glial histology, astrocytic tumors, oligodendroglial tumors, and mixed glioneuronal tumors. Considering the complexity of this evolving field, the purpose of this article is to offer a practical approach to the diagnosis of pediatric gliomas, including the selection of the most appropriate molecular surrogate immunohistochemical stains, basic molecular studies, and more sophisticated techniques if needed. The goal is to reach a rapid, sound diagnosis, helping guide clinical decision-making regarding prognosis and potential therapies.

Integrated Analysis of the Clinical and Molecular Characteristics of IDH Wild-Type Gliomas in the Chinese Glioma Genome Atlas

Purpose

Current studies and guidelines suggest that the biobehavior of IDH-wild type (IDH-wt) lower-grade glioma (LGG, WHO II-III) is similar to IDH-wt glioblastoma (GBM). However, differences in their clinical and molecular characteristics have not been reported. This study aimed to analyze the clinical and genetic information of gliomas with IDH-wt.

Methods

389 patients with IDH-wt were enrolled in the study (LGG=165, GBM=224), and their clinical and genetic information was collected from the Chinese Glioma Genome Atlas (CGGA). We conducted an analysis of this information between the two groups of patients and drew conclusions thereof.

Results

The median age of the LGG patients was 42 (18–74) years, whereas that of the GBM patients was 51 (18–79) years (P < 0.010). GBM patients were more likely to undergo total resection (P = 0.018) and had fewer epileptic seizure symptoms (P < 0.001). The median overall survival (OS) was 55 months for the LGG patients and only 14.83 months for the GBM patients (P < 0.01). The median progression-free survival (PFS) was 44 months for the LGG patients and only 9.767 months for the GBM patients (P < 0.001). GBM patients were more prone to PETN mutations (P = 0.010). Transcriptome analysis showed that the differentially expressed genes in LGG patients were mainly enriched in metabolic pathways and pathways in cancer and in the function of signal transduction and positive regulation of GTPase activity, whereas in GBM patients, they were mainly enriched in the PI3K-Akt signaling pathway and in the functions of apoptotic process and oxidation-reduction process.

Conclusions

Our data indicate that these two groups of patients should be re-evaluated and treated differently, despite both having IDH wild type.

Opposed Interplay between IDH1 Mutations and the WNT/β-Catenin Pathway: Added Information for Glioma Classification

Gliomas are the main common primary intraparenchymal brain tumor in the central nervous system (CNS), with approximately 7% of the death caused by cancers. In the WHO 2016 classification, molecular dysregulations are part of the definition of particular brain tumor entities for the first time. Nevertheless, the underlying molecular mechanisms remain unclear. Several studies have shown that 75% to 80% of secondary glioblastoma (GBM) showed IDH1 mutations, whereas only 5% of primary GBM have IDH1 mutations. IDH1 mutations lead to better overall survival in gliomas patients. IDH1 mutations are associated with lower stimulation of the HIF-1α a, aerobic glycolysis and angiogenesis. The stimulation of HIF-1α and the process of angiogenesis appears to be activated only when hypoxia occurs in IDH1-mutated gliomas. In contrast, the observed upregulation of the canonical WNT/β-catenin pathway in gliomas is associated with proliferation, invasion, aggressive-ness and angiogenesis.. Molecular pathways of the malignancy process are involved in early stages of WNT/β-catenin pathway-activated-gliomas, and this even under normoxic conditions. IDH1 mutations lead to decreased activity of the WNT/β-catenin pathway and its enzymatic targets. The opposed interplay between IDH1 mutations and the canonical WNT/β-catenin pathway in gliomas could participate in better understanding of the observed evolution of different tumors and could reinforce the glioma classification.

The diagnostic value of lower glucose consumption for IDH1 mutated gliomas on FDG-PET

Background

Non-invasive diagnosis of IDH1 mutation for gliomas has great clinical significance, and PET has natural advantage to detect metabolism, as IDH mutated gliomas share lower glucose consumption.

Methods

Clinical data of patients with gliomas and ¹⁸F-FDG PET were retrospectively reviewed. Receiver operating characteristic curve (ROC) analysis was conducted, and standard uptake value (SUV) was estimated in combination with grades or IDH1 mutation. The glucose consumption was investigated with U251 cells expressing wild-type or mutated IDH1 by glucose assay. Quantification of glucose was determined by HPLC in clinical tissues. Meanwhile, bioinformatics and western blot were applied to analyze the expression level of metabolic enzymes (e.g. HK1, PKM2, PC) in gliomas.

Results

Seventy-one glioma cases were enrolled, including 30 carrying IDH1 mutation. The sensitivity and specificity dependent on SUV_max (3.85) predicting IDH1 mutation reached 73.2 and 86.7%, respectively. The sensitivity and specificity of differentiating grades by SUVmax (3.1) were 92.3 and 64.4%, respectively. Glucose consumption of U251 IDH1 mutant cells (0.209 ± 0.0472 mg/ml) was obviously lower than IDH1wild-type cells (0.978 ± 0.0773 mg/ml, P = 0.0001) and astrocyte controls (0.335 ± 0.0592 mg/ml, P = 0.0451). Meanwhile, the glucose quantity in IDH1mutant glioma samples were significantly lower than those in IDH1 wild-type tissues (1.033 ± 1.19608 vs 6.361 ± 4.3909 mg/g, P = 0.0051). Silico analysis and western blot confirmed that HK1 and PKM2 in IDH1 wild-type gliomas were significantly higher than in IDH1 mutant group, while PC was significantly higher in IDH1 mutant gliomas.

Conclusion

SUV_max on PET can predict IDH1 mutation with adequate sensitivity and specificity, as is supported by reduced glucose consumption in IDH1 mutant gliomas.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07797-6.

An Immune-Related Signature for Predicting the Prognosis of Lower-Grade Gliomas

Background

Lower-grade gliomas (LGGs) have more favorable outcomes than glioblastomas; however, LGGs often progress to process glioblastomas within a few years. Numerous studies have proven that the tumor microenvironment (TME) is correlated with the prognosis of glioma.

Methods

LGG RNA-Sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA) were extracted and then divided into training and testing cohorts, respectively. Immune-related differentially expressed genes (DEGs) were screened to establish a prognostic signature by a multivariate Cox proportional hazards regression model. The immune-related risk score and clinical information, such as age, sex, World Health Organization (WHO) grade, and isocitrate dehydrogenase 1 (IDH1) mutation, were used to independently validate and develop a prognostic nomogram. GO and KEGG pathway analyses to DEGs between immune-related high-risk and low-risk groups were performed.

Results

Sixteen immune-related genes were screened for establishing a prognostic signature. The risk score had a negative correlation with prognosis, with an area under the receiver operating characteristic (ROC) curve of 0.941. The risk score, age, grade, and IDH1 mutation were identified as independent prognostic factors in patients with LGGs. The hazard ratios (HRs) of the high-risk score were 5.247 [95% confidence interval (CI) = 3.060–8.996] in the multivariate analysis. A prognostic nomogram of 1-, 3-, and 5-year survival was established and validated internally and externally. Go and KEGG pathway analyses implied that immune-related biological function and pathways were involved in the TME.

Conclusion

The immune-related prognostic signature and the prognostic nomogram could accurately predict survival.

Recent Trends of microRNA Significance in Pediatric Population Glioblastoma and Current Knowledge of Micro RNA Function in Glioblastoma Multiforme

Central nervous system tumors are a significant problem for modern medicine because of their location. The explanation of the importance of microRNA (miRNA) in the development of cancerous changes plays an important role in this respect. The first papers describing the presence of miRNA were published in the 1990s. The role of miRNA has been pointed out in many medical conditions such as kidney disease, diabetes, neurodegenerative disorder, arthritis and cancer. There are several miRNAs responsible for invasiveness, apoptosis, resistance to treatment, angiogenesis, proliferation and immunology, and many others. The research conducted in recent years analyzing this group of tumors has shown the important role of miRNA in the course of gliomagenesis. These particles seem to participate in many stages of the development of cancer processes, such as proliferation, angiogenesis, regulation of apoptosis or cell resistance to cytostatics.

RGS16 promotes glioma progression and serves as a prognostic factor

Background

RGS protein family members have recently became new potentially promising therapeutic targets in many cancers. However, as a key member of RGS family, RGS16 has seldom been studied in glioma. The present study was designed to investigate the prognostic value and biological function of RGS16 based on large‐scale databases and functional assays in vitro.

Methods

Here, we performed comprehensive analysis for the expression characteristic of RGS16 in Chinese Glioma Genome Atlas (CGGA) microarray database with 301 patients and validated in The Cancer Genome Atlas (TCGA) microarray and RNA sequencing database. Student's t‐test, one‐way ANOVA test and long‐rank test were used to assess differences between groups. Kaplan‐Meier survival, univariate and multivariate Cox analysis and ROC curve were used to estimate the survival distributions. Biological implication of abnormal expression of RGS16 in glioma was also explored. Functional analysis of RGS16 was performed in several glioblastoma (GBM) cell lines. R language and SPSS were used for statistical analysis and graphical work.

Results

We found that the expression of RGS16 was positively related to the grade of glioma. High level of RGS16 commonly gathered in glioma of mesenchymal subtype and wild‐type IDH1. Moreover, higher expression level of RGS16 was found to be significantly correlated with poor prognosis. The univariate and multivariate Cox regression analysis and ROC curve showed that RGS16 was an independent prognostic factor for glioma patients. Gene ontology analysis, gene set enrichment analysis, and gene set variation analysis suggested that the overexpression of RGS16 tightly related to cell proliferation, migration, epithelial‐mesenchymal transition (EMT), immune and inflammatory response of glioma. Knockdown of RGS16 in glioma cell lines also showed that RGS16 promoted the malignant progress of glioma cell lines.

Conclusions

RGS16 plays an important role in glioma progression and serves as an independent prognostic factor, especially in GBM patients.

Pediatric low-grade glioma in the era of molecular diagnostics

Low grade gliomas are the most frequent brain tumors in children and encompass a spectrum of histologic entities which are currently assigned World Health Organisation grades I and II. They differ substantially from their adult counterparts in both their underlying genetic alterations and in the infrequency with which they transform to higher grade tumors. Nonetheless, children with low grade glioma are a therapeutic challenge due to the heterogeneity in their clinical behavior – in particular, those with incomplete surgical resection often suffer repeat progressions with resultant morbidity and, in some cases, mortality. The identification of up-regulation of the RAS–mitogen-activated protein kinase (RAS/MAPK) pathway as a near universal feature of these tumors has led to the development of targeted therapeutics aimed at improving responses while mitigating patient morbidity. Here, we review how molecular information can help to further define the entities which fall under the umbrella of pediatric-type low-grade glioma. In doing so we discuss the specific molecular drivers of pediatric low grade glioma and how to effectively test for them, review the newest therapeutic agents and their utility in treating this disease, and propose a risk-based stratification system that considers both clinical and molecular parameters to aid clinicians in making treatment decisions.

Design and synthesis of novel 2-arylbenzimidazoles as selective mutant isocitrate dehydrogenase 2 R140Q inhibitors

A series of novel 2-arylbenzimidazoles have been designed, synthesized and evaluated for their inhibitory activity against IDH2 R140Q mutant. The preliminary results indicated that four compounds 7b, 7c, 7m and 7r displayed the potent inhibitory activity against IDH2 R140Q mutant. Among them, compound 7c showed the highest inhibitory activity, with the IC₅₀ value of 0.26 μM, which was more active than positive control enasidenib. The exquisite selectivity of 7c for IDH2 R140Q mutant isoform was demonstrated by the poor activity against the IDH1 R132C mutant, IDH1 R132H mutant, wild-type IDH1, IDH2 R172K mutant and the wild-type IDH2.

Alteration of Cellular Reduction Potential Will Change 64Cu-ATSM Signal With or Without Hypoxia

Therapies targeting reductive/oxidative (redox) metabolism hold potential in cancers resistant to chemotherapy and radiation. A redox imaging marker would help identify cancers susceptible to redox-directed therapies. Copper(II)-diacetyl-bis(4-methylthiosemicarbazonato) (Cu-ATSM) is a PET tracer developed for hypoxia imaging that could potentially be used for this purpose. We aimed to demonstrate that Cu-ATSM signal is dependent on cellular redox state, irrespective of hypoxia. Methods: We investigated the relationship between ⁶⁴Cu-ATSM signal and redox state in human cervical and colon cancer cells. We altered redox state using drug strategies and single-gene mutations in isocitrate dehydrogenases (IDH1/2). Concentrations of reducing molecules were determined by spectrophotometry and liquid chromatography-mass spectrometry and compared with ⁶⁴Cu-ATSM signal in vitro. Mouse models of cervical cancer were used to evaluate the relationship between ⁶⁴Cu-ATSM signal and levels of reducing molecules in vivo, as well as to evaluate the change in ⁶⁴Cu-ATSM signal after redox-active drug treatment. Results: A correlation exists between baseline ⁶⁴Cu-ATSM signal and cellular concentration of glutathione, nicotinamide adenine dinucleotide phosphate (NADPH), and nicotinamide adenine dinucleotide (NADH). Altering NADH and NADPH metabolism using drug strategies and IDH1 mutations resulted in significant changes in ⁶⁴Cu-ATSM signal under normoxic conditions. Hypoxia likewise changed ⁶⁴Cu-ATSM signal, but treatment of hypoxic cells with redox-active drugs resulted in a more dramatic change than hypoxia alone. A significant difference in NADPH was seen between cervical tumor orthotopic implants in vivo, without a corresponding difference in ⁶⁴Cu-ATSM signal. After treatment with β-lapachone, there was a change in ⁶⁴Cu-ATSM signal in xenograft tumors smaller than 50 mg but not in larger tumors. Conclusion: ⁶⁴Cu-ATSM signal reflects redox state, and altering redox state impacts ⁶⁴Cu-ATSM metabolism. Our animal data suggest there are other modulating factors in vivo. These findings have implications for the use of ⁶⁴Cu-ATSM as a predictive marker for redox therapies, though further in vivo work is needed.

Arterial spin labeling perfusion-weighted imaging aids in prediction of molecular biomarkers and survival in glioblastomas

OBJECTIVES

Prediction of progression-free survival (PFS) and overall survival (OS) and early identification of molecular biomarkers with prognostic information are clinically important in glioblastoma (GBM) patients. We aimed to explore the utility of arterial spin labeling perfusion-weighted imaging (ASL-PWI) in the prediction of molecular biomarkers and survival in GBM patients.

METHODS

We retrospectively analyzed 149 consecutive GBM patients, who had undergone maximal surgical resection or biopsy followed by concurrent chemoradiotherapy and adjuvant chemotherapy using temozolomide between November 2010 and June 2016. On preoperative ASL-PWI, cerebral blood flow (CBF) within contrast-enhancing (CE) and nonenhancing (NE) portions were evaluated both qualitatively (perfusion pattern_[CE] and perfusion pattern_[NE]) and quantitatively (nCBF_CE and nCBF_NE). ASL-PWI findings were correlated with molecular biomarkers, including isocitrate dehydrogenase (IDH) and O6-methylguanine-DNA methyltransferase (MGMT) methylation statuses, and survival, using the Mann-Whitney U-test, Spearman rank correlation, Kaplan-Meier analysis, and receiver operating characteristics analysis.

RESULTS

nCBF_CE was significantly higher in the IDH wild-type group than in the IDH mutant group (p = .013) and in the MGMT unmethylated group than in the methylated group (p = .047). Areas under the receiver operating characteristic curve were 0.678 for IDH mutation (p = .022) and 0.601 for MGMT promoter methylation (p = .043). Hyperperfusion was associated with the shortest median PFS for both perfusion pattern_[CE] (7.6 months) and perfusion pattern_[NE] (4.0 months). The perfusion pattern_[NE] remained an independent predictor for PFS and OS even after adjusting for clinical and molecular predictors, unlike perfusion pattern_[CE].

CONCLUSIONS

ASL-PWI can aid to predict survival and molecular biomarkers including IDH mutation and MGMT promoter methylation statuses in GBM patients.

KEY POINTS

• ASL-PWI can aid to predict survival in GBM patients. • ASL-PWI can aid to predict IDH and MGMT promoter methylation statuses in GBM.

Next Generation Sequencing-Based Transcriptome Predicts Bevacizumab Efficacy in Combination with Temozolomide in Glioblastoma

Glioblastoma (GBM), the most common and malignant brain tumor, is classified according to its isocitrate dehydrogenase (IDH) mutation status in the 2016 World Health Organization (WHO) brain tumor classification scheme. The standard treatment for GBM is maximal resection, radiotherapy, and Temozolomide (TMZ). Recently, Bevacizumab (Bev) has been added to basic therapy for newly diagnosed GBM, and monotherapy for recurrent GBM. However, the effect of IDH1 mutation on the combination of Bev and TMZ is unknown. In this study, we performed transcriptomic analysis by RNA sequencing with next generation sequencing (NGS), a newly developed powerful method that enables the quantification of the expression level of genome-wide genes. Extracellular matrix and immune cell migration genes were mainly upregulated whereas cell cycle genes were downregulated in IDH1-mutant U87 cells but not in IDH1-wildtype U87 cells after adding Bev to TMZ. In vitro and in vivo studies were conducted for further investigations to verify these results, and the addition of Bev to TMZ showed a significant antitumor effect only in the IDH1-mutant GBM xenograft model. Further studies of gene expression profiling in IDH1 mutation gliomas using NGS will provide more genetic information and will lead to new treatments for this refractory disease.

A Noninvasive Comparison Study between Human Gliomas with IDH1 and IDH2 Mutations by MR Spectroscopy

The oncogenes that are expressed in gliomas reprogram particular pathways of glucose, amino acids, and fatty acid metabolism. Mutations in isocitrate dehydrogenase genes (IDH1/2) in diffuse gliomas are associated with abnormally high levels of 2-hydroxyglutarate (2-HG) levels. The aim of this study was to determine whether metabolic reprogramming associated with IDH mutant gliomas leads to additional ¹H MRS-detectable differences between IDH1 and IDH2 mutations, and to identify metabolites correlated with 2-HG. A total of 21 glioma patients (age= 37 ± 11, 13 males) were recruited for magnetic resonance spectroscopy (MRS) using semi-localization by adiabatic selective refocusing pulse sequence at an ultra-high-field (7T). For 20 patients, the tumor mutation subtype was confirmed by immunohistochemistry and DNA sequencing. LCModel analysis was applied for metabolite quantification. A two-sample t-test was used for metabolite comparisons between IDH1 (n = 15) and IDH2 (n = 5) mutant gliomas. The Pearson correlation coefficients between 2-HG and associated metabolites were calculated. A Bonferroni correction was applied for multiple comparison. IDH2 mutant gliomas have a higher level of 2-HG/tCho (total choline=phosphocholine+glycerylphosphorylcholine) (2.48 ± 1.01vs.0.72 ± 0.38, Pc < 0.001) and myo-Inositol/tCho (2.70 ± 0.90 vs. 1.46 ± 0.51, Pc = 0.011) compared to IDH1 mutation gliomas. Associated metabolites, myo-Inositol and glucose+taurine were correlated with 2-HG levels. These results show the improved characterization of the metabolic pathways in IDH1 and IDH2 gliomas for precision medicine.

Oncogenic transgelin-2 is differentially regulated in isocitrate dehydrogenase wild-type vs. mutant gliomas

The presence of an isocitrate dehydrogenase (IDH1/2) mutation in gliomas is associated with favorable outcomes compared to gliomas without the mutation (IDH1/2 wild-type, WT). The underlying biological mechanisms accounting for improved clinical outcomes in IDH1/2 mutant gliomas remain poorly understood, but may, in part, be due to the glioma CpG island methylator phenotype (G-CIMP) and epigenetic silencing of genes. We performed profiling of IDH1/2 WT versus IDH1/2 mutant Grade II and III gliomas and identified transgelin-2 (TAGLN2), an oncogene and actin-polymerizing protein, to be expressed at significantly higher levels in IDH1/2 WT gliomas compared to IDH1/2 mutant gliomas. This differential expression of TAGLN2 was primarily due to promoter hypermethylation in IDH1/2 mutant gliomas, suggesting involvement of TAGLN2 in the G-CIMP. Our results also suggest that TAGLN2 may be involved in progression due to higher expression in glioblastomas compared to IDH1/2 WT gliomas of lower grades. Furthermore, our results suggest that TAGLN2 functions as an oncogene by contributing to proliferation and invasion when overexpressed in IDH1/2 WT glioma cells. Taken together, this study demonstrates a possible link between increased TAGLN2 expression, invasion and poor patient outcomes in IDH1/2 WT gliomas and identifies TAGLN2 as a potential novel therapeutic target for IDH1/2 WT gliomas.

A comprehensive review of available omics data resources and molecular profiling for precision glioma studies

Gliomas are the most common and lethal type of primary malignant central nervous system tumors, with an extremely poor prognosis. The latest progression in the technological development of sequencing/microarray and bioinformatics has provided insights into the glioma genome. These technologies have generated large amounts of easily accessible biological omics data, providing an unprecedented opportunity to study glioma formation. According to the 2016 WHO organization classification of brain tumors, gliomas are currently diagnosed with respect to morphological and molecular tumor alterations, especially for isocitrate dehydrogenase and 1p/19q codeletions. In the present study, the comprehensive molecular profiling and available omics data resources for malignant gliomas were reviewed for novel insights into the biology and classification of these tumors. These molecular profiling resources may be useful for improving the understanding of malignant gliomas, and to accelerate the clinical, experimental and epidemiological studies that may lead to improvements in the lives of patients with glioma.

CKAP2 expression is associated with glioma tumor growth and acts as a prognostic factor in high‑grade glioma

Cytoskeletal‑associated protein 2 (CKAP2), which is also known as tumor‑associated microtubule‑associated protein, has been reported to be dysregulated in various types of human cancer. However, the role of CKAP2 in glioma has not been fully elucidated. The present study evaluated the expression pattern of CKAP2 using the Chinese Glioma Genome Atlas microarray database, which included 301 patients, and validated the findings using The Cancer Genome Atlas RNA sequencing database. Kaplan‑Meier survival analysis, and univariate and multivariate Cox analyses, were used to estimate survival distributions. Furthermore, the biological implication of aberrant CKAP2 expression in high‑grade glioma (HGG) was investigated using Gene Ontology analysis, gene set enrichment analysis, gene set variation analysis and STRING. The results indicated that patients with HGG exhibited significantly higher CKAP2 expression levels compared with patients with low‑grade glioma in both databases. Higher expression levels of CKAP2 were significantly associated with shorter overall survival and progression‑free survival of patients with HGG. Furthermore, CKAP2 was also positively correlated with known malignant factors, including high Ki67 expression and phosphatase and tensin homolog mutations. The univariate and multivariate Cox regression analyses demonstrated that CKAP2 may be a novel independent prognostic biomarker for patients with HGG. Functional assays also indicated that CKAP2 was closely associated with the cell cycle, mitosis and cell proliferation. These results suggested that CKAP2 may be associated with tumor growth and could serve as an independent prognostic factor, particularly in patients with HGG.

IDH1 Arg-132 mutant promotes tumor formation through down-regulating p53

Resistance to apoptosis and uncontrolled proliferation are two hallmarks of cancer cells. p53 is crucial for apoptosis triggered by a broad range of stresses and a well-known gatekeeper for neoplastic transformation. Here we show that oncogenic IDH1 R132H/R132Q mutants robustly inhibit p53 expression and such an effect is attributed to 2-HG production. Mechanistically, 2-hydroxyglutarate (2-HG) stabilizes hypoxia-inducible factor-2α, which in turn activates the expression of miR-380-5p, a characterized microRNA against p53 expression. Rescue expression of p53 can inhibit the proliferation rate and impair the resistance of apoptosis induced by doxorubicin in IDH1 R132Q mouse embryonic fibroblast cells. Furthermore, p53 protein levels correlates negatively with IDH1 R132H levels in human glioma samples. Our results thus shed a new light on how p53 is down-regulated by 2-HG and suggests that impairment of p53-mediated apoptosis contributes to the tumorigenesis driven by IDH1 mutants.

A novel serum microRNA-based identification and classification biomarker of human glioma

Malignant glioma is one of the most common primary brain tumors that develop via multiple pathways and gene deregulation. MicroRNAs are involved in human cancer development and progression, and their serum expression profiles of glioma patients may be useful for classifying cancers. However, the profile and molecular mechanism of serum microRNAs for human glioma are poorly understood. Thus, it is crucial to analyze microRNA expression in human glioma serum to identify molecular subclasses and early stage of glioma. In this study, we performed microRNA alteration that contributes to glioma profile via analysis of The Cancer Genome Atlas RNA sequencing data and other independent Gene Expression Omnibus microarray data. We identified the glioma-associated novel microRNA as a key regulator of human glioma development and progression. The putative novel miR-1825 was validated by real-time polymerase chain reaction and its expression was significantly decreased in the serum of glioma patients compared with healthy controls. Patients with high miR-1825 expression had a longer survival rate. Interestingly, we found that miR-1825 expression levels were dependent on tumor size and pathological grading in glioma patients, but not associated with other factors including age and T classification. MicroRNA-Gene Ontology network indicated that miR-1825 may play an important role in the development of human glioma including apoptosis, cell proliferation, and invasion. In vitro assays of miR-1825 inhibit U87 cell proliferation and invasion and induce apoptosis. Furthermore, we provide evidence that the tumor-suppressive microRNA miR-1825 controls KLF2 expression. Reporter gene analyses revealed that both microRNAs directly targeted the 3'-untranslated region of KLF2 messenger RNA. These data demonstrated that miR-1825 expression in serum of human glioma was associated with tumorigenesis and miR-1825 may be used as a biomarker for identification of the pathological grade of glioma.

Targeted knockdown of polo-like kinase 1 alters metabolic regulation in melanoma

A limited number of studies have indicated an association of the mitotic kinase polo-like kinase 1 (PLK1) and cellular metabolism. Here, employing an inducible RNA interference approach in A375 melanoma cells coupled with a PCR array and multiple validation approaches, we demonstrated that PLK1 alters a number of genes associated with cellular metabolism. PLK1 knockdown resulted in a significant downregulation of IDH1, PDP2 and PCK1 and upregulation of FBP1. Ingenuity Pathway Analysis (IPA) identified that 1) glycolysis and the pentose phosphate pathway are major canonical pathways associated with PLK1, and 2) PLK1 inhibition-modulated genes were largely associated with cellular proliferation, with FBP1 being the key modulator. Further, BI 6727-mediated inhibition of PLK1 caused a decrease in PCK1 and increase in FBP1 in A375 melanoma cell implanted xenografts in vivo. Furthermore, an inverse correlation between PLK1 and FBP1 was found in melanoma cells, with FBP1 expression significantly downregulated in a panel of melanoma cells. In addition, BI 6727 treatment resulted in an upregulation in FBP1 in A375, Hs294T and G361 melanoma cells. Overall, our study suggests that PLK1 may be an important regulator of metabolism maintenance in melanoma cells.

The Process and Regulatory Components of Inflammation in Brain Oncogenesis

Central nervous system tumors comprising the primary cancers and brain metastases remain the most lethal neoplasms and challenging to treat. Substantial evidence points to a paramount role for inflammation in the pathology leading to gliomagenesis, malignant progression and tumor aggressiveness in the central nervous system (CNS) microenvironment. This review summarizes the salient contributions of oxidative stress, interleukins, tumor necrosis factor-α(TNF-α), cyclooxygenases, and transcription factors such as signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB) and the associated cross-talks to the inflammatory signaling in CNS cancers. The roles of reactive astrocytes, tumor associated microglia and macrophages, metabolic alterations, microsatellite instability, O⁶-methylguanine DNA methyltransferase (MGMT) DNA repair and epigenetic alterations mediated by the isocitrate dehydrogenase 1 (IDH1) mutations have been discussed. The inflammatory pathways with relevance to the brain cancer treatments have been highlighted.

Metabolic Alterations at the Crossroad of Aging and Oncogenesis

Aging represents the major risk factor for cancer. Cancer and aging are characterized by a similar dysregulated metabolism consisting in upregulation of glycolysis and downmodulation of oxidative phosphorylation. In this respect, metabolic interventions can be viewed as promising strategies to promote longevity and to prevent or delay age-related disorders including cancer. In this review, we discuss the most promising metabolic approaches including chronic calorie restriction, periodic fasting/fasting-mimicking diets, and pharmacological interventions mimicking calorie restriction. Metabolic interventions can also be viewed as adjuvant anticancer strategies to be combined to standard cancer therapy (chemotherapeutic agents, ionizing radiation, and drugs with specific molecular target), whose major limiting factors are represented by toxicity against healthy cells but also limited efficacy easily circumvented by tumor cells. In fact, conventional cancer therapy is unable to distinguish normal and cancerous cells and thus causes toxic side effects including secondary malignancies, cardiovascular and respiratory complications, endocrinopathies, and other chronic conditions, that resemble and, in some cases, accelerate the age-related disorders and profoundly affect the quality of life. In this scenario, geroscience contributes to the understanding of the mechanisms of protection of normal cells against a cytotoxic agent and finding strategies focused on the preserving healthy cells while enhancing the efficacy of the treatment against malignant cells.

Drug discovery strategies in the field of tumor energy metabolism: Limitations by metabolic flexibility and metabolic resistance to chemotherapy

The search for new drugs capable of blocking the metabolic vulnerabilities of human tumors has now entered the clinical evaluation stage, but several projects already failed in phase I or phase II. In particular, very promising in vitro studies could not be translated in vivo at preclinical stage and beyond. This was the case for most glycolysis inhibitors that demonstrated systemic toxicity. A more recent example is the inhibition of glutamine catabolism in lung adenocarcinoma that failed in vivo despite a strong addiction of several cancer cell lines to glutamine in vitro. Such contradictory findings raised several questions concerning the optimization of drug discovery strategies in the field of cancer metabolism. For instance, the cell culture models in 2D or 3D might already show strong limitations to mimic the tumor micro- and macro-environment. The microenvironment of tumors is composed of cancer cells of variegated metabolic profiles, supporting local metabolic exchanges and symbiosis, but also of immune cells and stroma that further interact with and reshape cancer cell metabolism. The macroenvironment includes the different tissues of the organism, capable of exchanging signals and fueling the tumor 'a distance'. Moreover, most metabolic targets were identified from their increased expression in tumor transcriptomic studies, or from targeted analyses looking at the metabolic impact of particular oncogenes or tumor suppressors on selected metabolic pathways. Still, very few targets were identified from in vivo analyses of tumor metabolism in patients because such studies are difficult and adequate imaging methods are only currently being developed for that purpose. For instance, perfusion of patients with [¹³C]-glucose allows deciphering the metabolomics of tumors and opens a new area in the search for effective targets. Metabolic imaging with positron emission tomography and other techniques that do not involve [¹³C] can also be used to evaluate tumor metabolism and to follow the efficiency of a treatment at a preclinical or clinical stage. Relevant descriptors of tumor metabolism are now required to better stratify patients for the development of personalized metabolic medicine. In this review, we discuss the current limitations in basic research and drug discovery in the field of cancer metabolism to foster the need for more clinically relevant target identification and validation. We discuss the design of adapted drug screening assays and compound efficacy evaluation methods for the discovery of innovative anti-cancer therapeutic approaches at the level of tumor energetics. This article is part of a Special Issue entitled Mitochondria in Cancer, edited by Giuseppe Gasparre, Rodrigue Rossignol and Pierre Sonveaux.

Prevalence and Prognostic Value of IDH1 R132 Mutation in Newly Diagnosed AML Egyptian Patients with Normal Karyotype

Mutation in IDH1 gene was suggested to be associated with bad prognosis in cytogenetically normal AML (CN-AML). However, there are conflicting data about its prognostic impact. Besides, its prevalence and prognostic significance in Egyptian patients still not fully stated. We aimed to assess the prevalence of IDH1^R132 mutation in Egyptian CN-AML patients, its correlation with FAB subtypes, and clinical outcome of those patients. Sequencing of amplified IDH1 gene exon four from 50 patients was performed to detect codon R132 point mutation. High prevalence of IDH1 mutation was detected in our patients (9/50, 18 %). Mutated IDH1^R132 was associated with older age and higher platelets count (p = 0.04 and 0.01 respectively). The most common FAB subtype associated with mutated IDH1^R132 was AML-M2 followed by M4. In multivariate analysis, IDH1^R132 mutation was found as independent prognostic variable. It was significantly associated with lower CR and shorter OS (p = 0.06 and 0.009 respectively).

Epigenomic Consequences of Coding and Noncoding Driver Mutations

Chromatin alterations are integral to the pathogenic process of cancer, as demonstrated by recent discoveries of frequent mutations in chromatin-modifier genes and aberrant DNA methylation states in different cancer types. Progress is being made on elucidating how chromatin alterations, and how proteins catalyzing these alterations, mechanistically contribute to tissue-specific tumorigenesis. In parallel, technologies enabling the genome-wide profiling of histone modifications have revealed the existence of noncoding driver genetic alterations in cancer. In this review, we survey the current knowledge of coding and noncoding cancer drivers, and discuss their impact on the chromatin landscape. Translational implications of these findings for novel cancer therapies are also presented.

An update on the epigenetics of glioblastomas

Glioblastomas, also known as glioblastoma multiforme (GBM), are the most aggressive and malignant type of primary brain tumor in adults, exhibiting notable variability at the histopathological, genetic and epigenetic levels. Recently, epigenetic alterations have emerged as a common hallmark of many tumors, including GBM. Considering that a deeper understanding of the epigenetic modifications that occur in GBM may increase the knowledge regarding the tumorigenesis, progression and recurrence of this disease, in this review we discuss the recent major advances in GBM epigenetics research involving histone modification, glioblastoma stem cells, DNA methylation, noncoding RNAs expression, including their main alterations and the use of epigenetic therapy as a valid option for GBM treatment.

The comparison of clinical and biological characteristics between IDH1 and IDH2 mutations in gliomas

Background

Mutations in isocitrate dehydrogenase 1 (IDH1) and isocitrate dehydrogenase 2 (IDH2) are frequent in low-grade gliomas and secondary glioblastomas (sGBM). Because they yield the same oncometabolite, D-2-hydroxyglutarate, they are often treated as equivalent and pooled. The objective of this study was to provide insight into the differences between IDH1 and IDH2 mutant gliomas.

Methods

To investigate the different clinical and molecular characterization between IDH1 mutant and IDH2 mutant gliomas, we studied 811 patients with IDH1 mutations, IDH2 mutations and IDH1/2 wild-type. In addition, whole-transcriptome sequencing and DNA methylation data were used to assess the distribution of genetic changes in IDH1 and IDH2 mutant gliomas in a Chinese population-based cohort.

Results

Among 811 gliomas in our cohort, 448 cases (55.2 %) harbored an IDH1 mutation, 18 cases (2.2 %) harbored an IDH2 mutation and 345 cases (42.6 %) harbored an IDH1/2 wild-type. We found that IDH1 and IDH2 are mutually exclusive in gliomas, and IDH2 mutations are mutually exclusive with PTEN, P53 and ATRX mutations. Patients with IDH2 mutations had a higher frequency of 1p/19q co-deletion (p < 0.05) than IDH1 mutant patients. In addition, a Gene Set Enrichment Analysis (GSEA) showed that IDH2 mutant gliomas were associated with the oxidative phosphorylation gene set, and the four most representative biological processes for genes commonly altered by hypermethylation in IDH2 mutant gliomas were the regulation of cell proliferation, cell motion, cell migration and response to hypoxia. Patients with IDH2 mutant gliomas exhibited longer Overall survival (OS) (p < 0.05) and longer Progression-free survival (PFS) (p < 0.05) than patients with IDH1/2 wild-type gliomas. However, their OS and PFS did not differ from that of IDH1 mutant patients.

Conclusions

Our study revealed an intrinsic distinction between IDH1 and IDH2 mutant gliomas, and these mutations should be considered separately because their differences could have implications for the diagnosis and treatment of IDH1/2 mutant gliomas.

Expression Profile Analysis of Zinc Transporters (ZIP4, ZIP9, ZIP11, ZnT9) in Gliomas and their Correlation with IDH1 Mutation Status

BACKGROUND

Zinc transporters have been considered as essential regulators in many cancers; however, their mechanisms remain unknown, especially in gliomas. Isocitrate dehydrogenase 1(IDH1) mutation is crucial to glioma. This study aimed to investigate whether zinc transporters are correlated with glioma grade and IDH1 mutation status.

MATERIALS AND METHODS

IDH1 mutation status and mRNA expression of four zinc transporters (ZIP4, ZIP9, ZIP11, and ZnT9) were determined by subjecting a panel of 74 glioma tissue samples to quantitative real-time PCR and pyrosequencing. The correlations between the expression levels of these zinc transporter genes and the grade of glioma, as well as IDH1 mutation status, were investigated.

RESULTS

Among the four zinc transporter genes, high ZIP4 expression and low ZIP11 expression were significantly associated with higher grade (grades III and IV) tumors compared with lower grade (grades I and II) counterparts (p<0.0001). However, only ZIP11 exhibited weak correlation with IDH1 mutation status (p=0.045). Samples with mutations in IDH1 displayed higher ZIP11 expression than those without IDH1 mutations.

CONCLUSIONS

This finding indicated that zinc transporters may interact with IDH1 mutation by direct modulation or action in some shared pathways or genes to promote the development of glioma. Zinc transporters may play an important role in glioma. ZIP4 and ZIP11 are promising molecular diagnostic markers and novel therapeutic targets. Nevertheless, the detailed biological function of zinc transporters and the mechanism of the potential interaction between ZIP11 and IDH1 mutation in gliomagenesis should be further investigated.

Neuroimaging

Imaging is integral to the management of patients with brain tumors. Conventional structural imaging provides exquisite anatomic detail but remains limited in the evaluation of molecular characteristics of intracranial neoplasms. Quantitative and physiologic biomarkers derived from advanced imaging techniques have been increasingly utilized as problem-solving tools to identify glioma grade and assess response to therapy. This chapter provides a comprehensive overview of the imaging strategies used in the clinical assessment of patients with gliomas and describes how novel imaging biomarkers have the potential to improve patient management.

Histone H3F3A and HIST1H3B K27M mutations define two subgroups of diffuse intrinsic pontine gliomas with different prognosis and phenotypes

Diffuse intrinsic pontine glioma (DIPG) is the most severe paediatric solid tumour, with no significant therapeutic progress made in the past 50 years. Recent studies suggest that diffuse midline glioma, H3-K27M mutant, may comprise more than one biological entity. The aim of the study was to determine the clinical and biological variables that most impact their prognosis. Ninety-one patients with classically defined DIPG underwent a systematic stereotactic biopsy and were included in this observational retrospective study. Histone H3 genes mutations were assessed by immunochemistry and direct sequencing, whilst global gene expression profiling and chromosomal imbalances were determined by microarrays. A full description of the MRI findings at diagnosis and at relapse was integrated with the molecular profiling data and clinical outcome. All DIPG but one were found to harbour either a somatic H3-K27M mutation and/or loss of H3K27 trimethylation. We also discovered a novel K27M mutation in HIST2H3C, and a lysine-to-isoleucine substitution (K27I) in H3F3A, also creating a loss of trimethylation. Patients with tumours harbouring a K27M mutation in H3.3 (H3F3A) did not respond clinically to radiotherapy as well, relapsed significantly earlier and exhibited more metastatic recurrences than those in H3.1 (HIST1H3B/C). H3.3-K27M-mutated DIPG have a proneural/oligodendroglial phenotype and a pro-metastatic gene expression signature with PDGFRA activation, while H3.1-K27M-mutated tumours exhibit a mesenchymal/astrocytic phenotype and a pro-angiogenic/hypoxic signature supported by expression profiling and radiological findings. H3K27 alterations appear as the founding event in DIPG and the mutations in the two main histone H3 variants drive two distinct oncogenic programmes with potential specific therapeutic targets.

Radiological features combined with IDH1 status for predicting the survival outcome of glioblastoma patients

BACKGROUND

Radiological characteristics may reflect the biological features of brain tumors and may be associated with genetic alterations that occur in tumorigenesis. This study aimed to investigate the relationship between radiological features and IDH1 status as well as their predictive value for survival of glioblastoma patients.

METHODS

The clinical information and MR images of 280 patients with histologically confirmed glioblastoma were retrospectively reviewed. The radiological characteristics of tumors were examined on MR images, and the IDH1 status was determined using DNA sequencing for all cases. The Kaplan-Meier method and Cox regression model were used to identify prognostic factors for progression-free and overall survival.

RESULTS

The IDH1 mutation was associated with longer progression-free survival (P = .022; hazard ratio, 0.602) and overall survival (P = .018; hazard ratio, 0.554). In patients with the IDH1 mutation, tumor contrast enhancement and peritumoral edema indicated worse progression-free survival (P = .015 and P = .024, respectively) and worse overall survival (P = .024 and P = .032, respectively). For tumors with contrast enhancement, multifocal contrast enhancement of the tumor lesion was associated with poor progression-free survival (P = .002) and poor overall survival (P = .010) in patients with wild-type IDH1 tumors.

CONCLUSIONS

Combining the radiological features and IDH1 status of a tumor allows more accurate prediction of survival outcomes in glioblastoma patients. The complementary roles of genetic changes and radiological features of tumors should be considered in future studies.

MR Imaging-Based Analysis of Glioblastoma Multiforme: Estimation of IDH1 Mutation Status

BACKGROUND AND PURPOSE

Glioblastoma multiforme is highly aggressive and the most common type of primary malignant brain tumor in adults. Imaging biomarkers may provide prognostic information for patients with this condition. Patients with glioma with isocitrate dehydrogenase 1 (IDH1) mutations have a better clinical outcome than those without such mutations. Our purpose was to investigate whether the IDH1 mutation status in glioblastoma multiforme can be predicted by using MR imaging.

MATERIALS AND METHODS

We retrospectively studied 55 patients with glioblastoma multiforme with wild type IDH1 and 11 patients with mutant IDH1. Absolute tumor blood flow and relative tumor blood flow within the enhancing portion of each tumor were measured by using arterial spin-labeling data. In addition, the maximum necrosis area, the percentage of cross-sectional necrosis area inside the enhancing lesions, and the minimum and mean apparent diffusion coefficients were obtained from contrast-enhanced T1-weighted images and diffusion-weighted imaging data. Each of the 6 parameters was compared between patients with wild type IDH1 and mutant IDH1 by using the Mann-Whitney U test. The performance in discriminating between the 2 entities was evaluated by using receiver operating characteristic analysis.

RESULTS

Absolute tumor blood flow, relative tumor blood flow, necrosis area, and percentage of cross-sectional necrosis area inside the enhancing lesion were significantly higher in patients with wild type IDH1 than in those with mutant IDH1 (P < .05 each). In contrast, no significant difference was found in the ADC(minimum) and ADC(mean). The area under the curve for absolute tumor blood flow, relative tumor blood flow, percentage of cross-sectional necrosis area inside the enhancing lesion, and necrosis area were 0.850, 0.873, 0.739, and 0.772, respectively.

CONCLUSIONS

Tumor blood flow and necrosis area calculated from MR imaging are useful for predicting the IDH1 mutation status.

Molecular characteristics of pediatric high-grade gliomas

High-grade gliomas (HGGs) are extremely lethal tumors. Survival has not changed significantly in the past decades. The only known prognostic factors in pediatric HGGs (pHGGs) are extent of resection and histologic grade. Treatment has historically been based on adult trials because of the rarity of pHGGs and the lack of genomic tools to explore their unique molecular characteristics. The recent advances in molecular biological data helped divide these tumors into distinct subgroups. In this review, the authors focus on major molecular targets of alterations in pHGGs: histone H3.3, telomeres, PDGFRA, IDH, BRAF (V600E), ACVR1 and NTRK and briefly highlight the difference with the adult counterpart.

Prognostic impact of molecular phenotype in patients with recurrent anaplastic glioma treated with prolonged administration of temozolomide

We retrospectively investigated the prognostic impact of molecular phenotypes in patients with recurrent anaplastic glioma treated with prolonged administration of temozolomide (TMZ). Malignant gliomas have a dismal prognosis despite the available multimodal treatments. We reviewed 87 patients who were diagnosed with recurrent anaplastic gliomas between March 2004 and June 2010, and 58 were enrolled for analysis. In the cohort, 21 patients had anaplastic oligodendrogliomas, 18 anaplastic oligoastrocytomas and 19 anaplastic astrocytomas. All patients were initially treated with surgical resection or biopsy followed by involved-field radiotherapy. At recurrence, patients were treated with 150-200mg/m(2) of TMZ on days 1-5 in 28 day cycles until disease progression. We evaluated the association of molecular phenotypes, including 1p19q deletion, O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status, isocitrate dehydrogenase-1 (IDH1) mutation and other clinico-histopathological findings with treatment outcome. During the mean follow-up period of 34.6 months, 33 patients were still alive (56.9%). Median survival from recurrence was 39.7 months (95% confidence interval [CI] 22.7-56.7). Time to progression from administration of TMZ was 6.4 months (95% CI 5.0-7.8). Univariate analysis demonstrated that the presence of the IDH1 mutation was closely associated with treatment response (8.4 versus 3.8 months; p=0.015). Oligodendroglial lineage, 1p19q deletion status and MGMT promoter methylation status were not independent variables for determining the TMZ treatment outcome. In recurrent anaplastic gliomas, TMZ treatment is an effective modality regardless of MGMT methylation status or histological type. The IDH1 mutation has the most powerful prognostic impact on overall patient survival.

Pediatric diffuse intrinsic pontine glioma: can optimism replace pessimism?

Pediatric diffuse intrinsic pontine glioma (DIPG) has a dismal prognosis that has not seen a change in outcome despite multiple clinical trials. Possible reasons for failure to make progress in this aggressive childhood brain tumor include: poor understanding of the underlying molecular biology due to lack of access to tumor material; absence of accurate and relevant DIPG preclinical models for drug development; ill-defined therapeutic targets for novel agents; and inadequate drug delivery to the brainstem. This review will demonstrate that systematic studies to identify solutions for each of these barriers is starting to deliver progress that can turn pessimism to optimism in DIPG.

Profiling metabolic states with genetically encoded fluorescent biosensors for NADH

NADH and its oxidized form, NAD(+), play central roles in energy metabolism and are ideal indicators of cellular metabolic states. In this review, we will introduce recent progress made in the developing of a series of genetically encoded NADH sensors, which offer the potential to fill the gap in currently used techniques of endogenous NAD(P)H fluorescence imaging. These sensors are bright, specific and organelles targetable, allowing real-time tracking and quantification of intracellular NADH levels in different subcellular compartments. The individual strengths and weaknesses of these sensors when applied to the study of metabolic states profiling will be also discussed.

Lentiviral-induced high-grade gliomas in rats: the effects of PDGFB, HRAS-G12V, AKT, and IDH1-R132H

In human gliomas, the RTK/RAS/PI(3)K signaling pathway is nearly always altered. We present a model of experimental gliomagenesis that elucidates the contributions of genes involved in this pathway (PDGF-B ligand, HRAS-G12V, and AKT). We also examine the effect on gliomagenesis by the potential modifier gene, IDH1-R132H. Injections of lentiviral-encoded oncogenes induce de novo gliomas of varying penetrance, tumor progression, and histological grade depending on the specific oncogenes used. Our model mimics hallmark histological structures of high-grade glioma, such as pseudopalisades, glomeruloid microvascular proliferation, and diffuse tumor invasion. We use our model of gliomagenesis to test the efficacy of an experimental brain tumor gene therapy. Our model allowed us to test the contributions of oncogenes in the RTK/RAS/PI(3)K pathway, and their potential modification by over-expression of mutated IDH1, in glioma development and progression in rats. Our model constitutes a clinically relevant system to study gliomagenesis, the effects of modifier genes, and the efficacy of experimental therapeutics.

O-GlcNAc signaling in cancer metabolism and epigenetics

The covalent attachment of β-D-N-acetylglucosamine monosaccharides (O-GlcNAc) to serine/threonine residues of nuclear and cytoplasmic proteins is a major regulatory mechanism in cell physiology. Aberrant O-GlcNAc modification of signaling proteins, metabolic enzymes, and transcriptional and epigenetic regulators has been implicated in cancer. Relentless growth of cancer cells requires metabolic reprogramming that is intertwined with changes in the epigenetic landscape. This review highlights the emerging role of protein O-GlcNAcylation at the interface of cancer metabolism and epigenetics.