INI1 immunohistochemical expression in glioblastoma: correlation with MGMT gene promoter methylation status and patient survival

Embryonal Tumors of the Central Nervous System: The WHO 2016 Classification and New Insights

Central nervous system tumors comprise 26% of cancer in children, representing the most frequent solid neoplasms. Embryonal tumors comprise 15% of them, and they are defined as "small round blue cells" in which morphology is reminiscent of the developing embryonic nervous system. They are the most common high-grade central nervous system neoplasms. Over the years, molecular research has been improving our knowledge concerning these neoplasms, stressing the need for tumor reclassification. Indeed, the revised 2016 fourth edition of the World Health Organization classification introduced genetic parameters in the classification. Specific molecular signatures allow a more accurate risk assessment, leading to proper therapeutic approach and potentially improved prognosis. Holding this new approach, medulloblastoma is noteworthy. The present classification combines the previous histologic classification with a new genetic definition in WNT-activated, sonic hedgehog-activated and non-WNT/non-sonic hedgehog. Molecular data are also a defining feature in the diagnosis of atypical teratoid/rhabdoid tumors and embryonal tumors with multilayered rosettes. However, there are still embryonal tumors that challenge the present World Health Organization classification, and new molecular data have been underlining the need for novel tumor entities. Likewise, recent research has been highlighting heterogeneity in recognized entities. How to translate these molecular developments into routine clinical practice is still a major challenge.

Prognostic value of test(s) for O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation for predicting overall survival in people with glioblastoma treated with temozolomide

BACKGROUND

Glioblastoma is an aggressive form of brain cancer. Approximately five in 100 people with glioblastoma survive for five years past diagnosis. Glioblastomas that have a particular modification to their DNA (called methylation) in a particular region (the O6-methylguanine-DNA methyltransferase (MGMT) promoter) respond better to treatment with chemotherapy using a drug called temozolomide.

OBJECTIVES

To determine which method for assessing MGMT methylation status best predicts overall survival in people diagnosed with glioblastoma who are treated with temozolomide.

SEARCH METHODS

We searched MEDLINE, Embase, BIOSIS, Web of Science Conference Proceedings Citation Index to December 2018, and examined reference lists. For economic evaluation studies, we additionally searched NHS Economic Evaluation Database (EED) up to December 2014.

SELECTION CRITERIA

Eligible studies were longitudinal (cohort) studies of adults with diagnosed glioblastoma treated with temozolomide with/without radiotherapy/surgery. Studies had to have related MGMT status in tumour tissue (assessed by one or more method) with overall survival and presented results as hazard ratios or with sufficient information (e.g. Kaplan-Meier curves) for us to estimate hazard ratios. We focused mainly on studies comparing two or more methods, and listed brief details of articles that examined a single method of measuring MGMT promoter methylation. We also sought economic evaluations conducted alongside trials, modelling studies and cost analysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook all steps of the identification and data extraction process for multiple-method studies. We assessed risk of bias and applicability using our own modified and extended version of the QUality In Prognosis Studies (QUIPS) tool. We compared different techniques, exact promoter regions (5'-cytosine-phosphate-guanine-3' (CpG) sites) and thresholds for interpretation within studies by examining hazard ratios. We performed meta-analyses for comparisons of the three most commonly examined methods (immunohistochemistry (IHC), methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ)), with ratios of hazard ratios (RHR), using an imputed value of the correlation between results based on the same individuals.

MAIN RESULTS

We included 32 independent cohorts involving 3474 people that compared two or more methods. We found evidence that MSP (CpG sites 76 to 80 and 84 to 87) is more prognostic than IHC for MGMT protein at varying thresholds (RHR 1.31, 95% confidence interval (CI) 1.01 to 1.71). We also found evidence that PSQ is more prognostic than IHC for MGMT protein at various thresholds (RHR 1.36, 95% CI 1.01 to 1.84). The data suggest that PSQ (mainly at CpG sites 74 to 78, using various thresholds) is slightly more prognostic than MSP at sites 76 to 80 and 84 to 87 (RHR 1.14, 95% CI 0.87 to 1.48). Many variants of PSQ have been compared, although we did not see any strong and consistent messages from the results. Targeting multiple CpG sites is likely to be more prognostic than targeting just one. In addition, we identified and summarised 190 articles describing a single method for measuring MGMT promoter methylation status.

AUTHORS' CONCLUSIONS

PSQ and MSP appear more prognostic for overall survival than IHC. Strong evidence is not available to draw conclusions with confidence about the best CpG sites or thresholds for quantitative methods. MSP has been studied mainly for CpG sites 76 to 80 and 84 to 87 and PSQ at CpG sites ranging from 72 to 95. A threshold of 9% for CpG sites 74 to 78 performed better than higher thresholds of 28% or 29% in two of three good-quality studies making such comparisons.

Tumor-Suppressive Function of lncRNA-MEG3 in Glioma Cells by Regulating miR-6088/SMARCB1 Axis

Objective

Mounting evidence has elaborated the implication of long noncoding RNAs (lncRNAs) in tumorigenesis of several cancers, including glioma. However, little was known about the mechanism of lncRNA maternally expressed gene 3 (MEG3) in the development and progression of glioma. This work is designed to explore the effect of MEG3 on glioma progression and its possible mechanism.

Methods

Expressions of lncRNA-MEG3 and SMARCB1 were detected in human glioblastoma U87 and U251 cell lines. Gain and loss of function of MEG3 or/and miR-6088 was performed in U87 and U251 cells to observe its effect on cell proliferation and migration as well as on epithelial-mesenchymal transition (EMT) related markers. Luciferase reporter gene assay was employed to inspect the interactions among MEG3, miR-6088, and SMARCB1.

Results

MEG3 and SMARCB1 expressions were downregulated in glioma cells. Transfection of pcDNA3.1-MEG3 or pcDNA3.1-SMARCB1 plasmids could clearly block cell proliferation, migration, and EMT progression. MEG3 functions as a sponge for miR-6088, while SMARCB1 is a downstream protein of miR-6088. Transfection of miR-6088 mimic or si-SMARCB1 could obviously reverse the favorable effect of pcDNA3.1-MEG3 on glioma progression.

Conclusion

Collectively, the evidence in this study indicated that MEG3 was downregulated in glioma cells and inhibited proliferation and migration of glioma cells via regulating miR-6088/SMARCB1 axis.

Calvarium mass as the first presentation of glioblastoma multiforme: A very rare manifestation of high-grade glioma

Glioblastoma multiforme (GBM) is a high grade glial tumor, primarily located in cerebral hemispheres. The most common clinical presentations are slowly progressive neurological deficit such as motor weakness, seizure, and headaches that last less than three months. Calvarium and extra-axial invasion are very rare and generally occur after a brain biopsy or surgery, or secondary to radiotherapy of primary intra-axial glial tumors. We report a case of GBM with calvarium involvement in a 60-year-old man who presented with a frontal bump and left-sided clumsiness. Imaging studies revealed a tumoral lesion that destroyed the frontal bone with white matter involvement of the frontal lobe and extension into the corpus callosum. Histopathological examination of intra-axial and extra-axial lesions revealed pleomorphic high-grade tumor with large areas of necrosis and hemorrhage. Immunohistochemical (IHC) studies confirmed GBM that spread directly into the dura, galea, and calvarium (positive reaction for GFAP, S-100, CD68, OLIG2, and p53). The patient was treated with radiotherapy (60Gy/30 fractions) and concomitant temozolomide. Unfortunately, the patient died seven months after the initial diagnosis.

Is the prognostic significance of O6-methylguanine- DNA methyltransferase promoter methylation equally important in glioblastomas of patients from different continents? A systematic review with meta-analysis

BACKGROUND

O6-methylguanine-DNA methyltransferase (MGMT) is an independent predictor of therapeutic response and potential prognosis in patients with glioblastoma multiforme (GBM). However, its significance of clinical prognosis in different continents still needs to be explored.

PATIENTS AND METHODS

To explore the effects of MGMT promoter methylation on both progression-free survival (PFS) and overall survival (OS) among GBM patients from different continents, a systematic review of published studies was conducted.

RESULTS

A total of 5103 patients from 53 studies were involved in the systematic review and the total percentage of MGMT promoter methylation was 45.53%. Of these studies, 16 studies performed univariate analyses and 17 performed multivariate analyses of MGMT promoter methylation on PFS. The pooled hazard ratio (HR) estimated for PFS was 0.55 (95% CI 0.50, 0.60) by univariate analysis and 0.43 (95% CI 0.38, 0.48) by multivariate analysis. The effect of MGMT promoter methylation on OS was explored in 30 studies by univariate analysis and in 30 studies by multivariate analysis. The combined HR was 0.48 (95% CI 0.44, 0.52) and 0.42 (95% CI 0.38, 0.45), respectively.

CONCLUSION

In each subgroup divided by areas, the prognostic significance still remained highly significant. The proportion of methylation in each group was in inverse proportion to the corresponding HR in the univariate and multivariate analyses of PFS. However, from the perspective of OS, compared with data from Europe and the US, higher methylation rates in Asia did not bring better returns.

Development of an Atypical Teratoid Rhabdoid Tumor in a Meningioma

We describe an atypical teratoid rhabdoid tumor (AT/RT) with a component of low-grade and anaplastic rhabdoid meningioma in a 7-year-old child. The AT/RT was uniformly negative for INI1 and displayed immunoreactivity for vimentin, P53, CD99, cytokeratins with AE1/AE3 antibodies, epithelial membrane antigen, β-catenin, smooth muscle actin, E-cadherin, and S-100 protein. AT/RT was continuous, with small foci of recognizable low-grade and anaplastic meningioma. The low-grade meningioma was INI1 positive with scattered INI1-negative nuclei, whereas the remaining tumor components were INI1 negative. A recurrent tumor 6 months after partial resection contained only INI1-negative AT/RT. This case supports the hypothesis that rare examples of AT/RT may emerge from a preexisting “parent” neoplasm as a result of a second hit mutation.

The prognosis of MGMT promoter methylation in glioblastoma patients of different race: a meta-analysis

O(6)-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair gene. Epigenetic silencing of the MGMT promoter methylation compromises DNA repair and has been associated with longer survival in patients with glioblastoma (GBM) who receive alkylating agents. But the prognostic of MGMT promoter methylation in GBM patients of different race is still ambiguous. Based on an univariate or multivariate analysis between different race (Caucasian and Asian), a meta-analysis of the effects of MGMT promoter methylation on both progression-free survival (PFS) and overall survival (OS) among GBM patients was conducted. A total of 6,309 patients from 50 studies were involved in the analysis. Random effect models were applied to estimate the pooled hazard ratio (HR) with 95 % confidence intervals (CIs) for GBM patients of different race prognosis, the Chi square-based Q test was used to test heterogeneity. Begg's (funnel plot method) and Egger's linear regression tests were adopted to check publication bias (a bias with regard to what is likely to be published, among what is available to be published). The HR value estimated for OS was 0.524 (95 % CI 0.428-0.640) by univariate analysis and 0.427 (95 % CI 0.355-0.513) by multivariate analysis in Caucasian. The HR value estimated for OS was 0.892 (95 % CI 0.469-1.698) by univariate analysis and 0.562 (95 % CI 0.394-0.804) by multivariate analysis in Asian. The HR value estimated for PFS was 0.526 (95 % CI 0.372-0.743) by univariate analysis and 0.437 (95 % CI 0.356-0.537) by multivariate analysis in Caucasian. The HR value estimated for PFS was 0.132 (95 % CI 0.006-3.027) by multivariate analysis in Asian. This data revealed that GBM patients with MGMT promoter methylation had longer OS and PFS by univariate or multivariate analysis in Caucasian regardless of therapeutic intervention. However, GBM patients with MGMT promoter methylation only had longer OS by multivariate analysis in Asian.

The prognostic value of MGMT promoter methylation in Glioblastoma multiforme: a meta-analysis

The prognostic significance of O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation on Glioblastoma multiforme (GBM) remains controversial. A meta-analysis of published studies investigating the effects of MGMT promoter methylation on both progression-free survival (PFS) and overall survival (OS) among GBM patients was performed. A total of 2,986 patients from 30 studies were included in the meta-analysis. In all, the frequency of MGMT promoter methylation was 44.27 %. Five studies undertook univariate analyses and nine undertook multivariate analyses of MGMT promoter methylation on PFS. The pooled hazard ratio (HR) estimate for PFS was 0.72 (95 % CI 0.55-0.95) by univariate analysis and 0.51 (95 % CI 0.38-0.69) by multivariate analysis. The effect of MGMT promoter methylation on OS was evaluated in 15 studies by univariate analysis and 14 studies by multivariate analysis. The combined HR was 0.67 (95 % CI 0.58-0.78) and 0.49 (95 % CI 0.38-0.64), respectively. For GBM patients treated with Alkylating agent, the meta-risk remained highly significant by both univariate (HR = 0.58; 95 % CI 0.42-0.79) and multivariate analysis (HR = 0.42; 95 % CI 0.29-0.60). This study showed that MGMT promoter methylation was associated with better PFS and OS in patients with GBM regardless of therapeutic intervention, and associated with longer OS in GBM patients treated with alkylating agents.