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8 Publications visible to you, out of a total of 8
Combined SOM-portrayal of gene expression and DNA methylation landscapes disentangles modes of epigenetic regulation in glioblastoma.
GGN - German Glioma Network

Abstract (Expand)

AIM: We present here a novel method that enables unraveling the interplay between gene expression and DNA methylation in complex diseases such as cancer. MATERIALS & METHODS: The method is based … on self-organizing maps and allows for analysis of data landscapes from 'governed by methylation' to 'governed by expression'. RESULTS: We identified regulatory modules of coexpressed and comethylated genes in high-grade gliomas: two modes are governed by genes hypermethylated and underexpressed in IDH-mutated cases, while two other modes reflect immune and stromal signatures in the classical and mesenchymal subtypes. A fifth mode with proneural characteristics comprises genes of repressed and poised chromatin states active in healthy brain. Two additional modes enrich genes either in active or repressed chromatin states. CONCLUSION: The method disentangles the interplay between gene expression and methylation. It has the potential to integrate also mutation and copy number data and to apply to large sample cohorts.

Authors: L. Hopp, H. Loffler-Wirth, J. Galle, H. Binder

Date Published: 12th Jun 2018

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Limited role for transforming growth factor-beta pathway activation-mediated escape from VEGF inhibition in murine glioma models.
GGN - German Glioma Network

Abstract (Expand)

BACKGROUND: The vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-beta pathways regulate key biological features of glioblastoma. Here we explore whether the TGF-beta … pathway, which promotes angiogenesis, invasiveness, and immunosuppression, acts as an escape pathway from VEGF inhibition. METHODS: The role of the TGF-beta pathway in escape from VEGF inhibition was assessed in vitro and in vivo and by gene expression profiling in syngeneic mouse glioma models. RESULTS: We found that TGF-beta is an upstream regulator of VEGF, whereas VEGF pathway activity does not alter the TGF-beta pathway in vitro. In vivo, single-agent activity was observed for the VEGF antibody B20-4.1.1 in 3 and for the TGF-beta receptor 1 antagonist LY2157299 in 2 of 4 models. Reduction of tumor volume and blood vessel density, but not induction of hypoxia, correlated with benefit from B20-4.1.1. Reduction of phosphorylated (p)SMAD2 by LY2157299 was seen in all models but did not predict survival. Resistance to B20 was associated with anti-angiogenesis escape pathway gene expression, whereas resistance to LY2157299 was associated with different immune response gene signatures in SMA-497 and GL-261 on transcriptomic profiling. The combination of B20 with LY2157299 was ineffective in SMA-497 but provided prolongation of survival in GL-261, associated with early suppression of pSMAD2 in tumor and host immune cells, prolonged suppression of angiogenesis, and delayed accumulation of tumor infiltrating microglia/macrophages. CONCLUSIONS: Our study highlights the biological heterogeneity of murine glioma models and illustrates that cotargeting of the VEGF and TGF-beta pathways might lead to improved tumor control only in subsets of glioblastoma.

Authors: D. Mangani, M. Weller, E. Seyed Sadr, E. Willscher, K. Seystahl, G. Reifenberger, G. Tabatabai, H. Binder, H. Schneider

Date Published: 12th Jun 2016

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Genomic profiling reveals distinctive molecular relapse patterns in IDH1/2 wild-type glioblastoma.
GGN - German Glioma Network

Abstract (Expand)

Molecular changes associated with the progression of glioblastoma after standard radiochemotherapy remain poorly understood. We compared genomic profiles of 27 paired primary and recurrent IDH1/2 … wild-type glioblastomas by genome-wide array-based comparative genomic hybridization. By bioinformatic analysis, primary and recurrent tumor profiles were normalized and segmented, chromosomal gains and losses identified taking the tumor cell content into account, and difference profiles deduced. Seven of 27 (26%) pairs lacked DNA copy number differences between primary and recurrent tumors (equal pairs). The recurrent tumors in 9/27 (33%) pairs contained all chromosomal imbalances of the primary tumors plus additional ones, suggesting a sequential acquisition of and/or selection for aberrations during progression (sequential pairs). In 11/27 (41%) pairs, the profiles of primary and recurrent tumors were divergent, i.e., the recurrent tumors contained additional aberrations but had lost others, suggesting a polyclonal composition of the primary tumors and considerable clonal evolution (discrepant pairs). Losses on 9p21.3 harboring the CDKN2A/B locus were significantly more common in primary tumors from sequential and discrepant (nonequal) pairs. Nonequal pairs showed ten regions of recurrent genomic differences between primary and recurrent tumors harboring 46 candidate genes associated with tumor recurrence. In particular, copy numbers of genes encoding apoptosis regulators were frequently changed at progression. In summary, approximately 25% of IDH1/2 wild-type glioblastoma pairs have stable genomic imbalances. In contrast, approximately 75% of IDH1/2 wild-type glioblastomas undergo further genomic aberrations and alter their clonal composition upon recurrence impacting their genomic profile, a process possibly facilitated by 9p21.3 loss in the primary tumor. (c) 2014 Wiley Periodicals, Inc.

Authors: V. Riehmer, J. Gietzelt, U. Beyer, B. Hentschel, M. Westphal, G. Schackert, M. C. Sabel, B. Radlwimmer, T. Pietsch, G. Reifenberger, M. Weller, R. G. Weber, M. Loeffler

Date Published: 8th Apr 2014

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Long-term survival in primary glioblastoma with versus without isocitrate dehydrogenase mutations.
GGN - German Glioma Network

Abstract (Expand)

PURPOSE: The determinants of long-term survival in glioblastoma have remained largely obscure. Isocitrate dehydrogenase (IDH) 1 or 2 mutations are common in World Health Organization (WHO) grades II … and III gliomas, but rare in primary glioblastomas, and associated with longer survival. EXPERIMENTAL DESIGN: We compared clinical and molecular characteristics of 69 patients with centrally confirmed glioblastoma and survival >36 months (LTS-36), including 33 patients surviving >60 months (LTS-60), with 257 patients surviving <36 months. MGMT promoter methylation, 1p/19q codeletions, EGFR amplification, TP53 mutations, and IDH1/2 mutations were determined by standard techniques. RESULTS: The rate of IDH1/2 mutations in LTS-36 patients was 34% (23 of 67 patients) as opposed to 4.3% in controls (11 of 257 patients). Long-term survivors with IDH1/2-mutant glioblastomas were younger, had almost no EGFR amplifications, but exhibited more often 1p/19q codeletions and TP53 mutations than LTS patients with IDH1/2 wild-type glioblastomas. Long-term survivors with IDH1/2 wild-type showed no distinguishing features from other patients with IDH1/2 wild-type glioblastomas except for a higher rate of MGMT promoter methylation. Similarly, among 11 patients with IDH1/2-mutant glioblastomas without long-term survival, the only difference to IDH1/2-mutant long-term survivors was less-frequent MGMT promoter methylation. Compared with LTS-36 patients, LTS-60 patients had less frequently TP53 mutations and radiotherapy alone as initial treatment. CONCLUSIONS: IDH1/2 mutations define a subgroup of tumors of LTS patients that exhibit molecular characteristics of WHO grade II/III gliomas and secondary glioblastomas. Determinants of LTS with IDH1/2 wild-type glioblastomas, which exhibit typical molecular features of primary glioblastomas, beyond MGMT promoter methylation, remain to be identified.

Authors: C. Hartmann, B. Hentschel, M. Simon, M. Westphal, G. Schackert, J. C. Tonn, M. Loeffler, G. Reifenberger, T. Pietsch, A. von Deimling, M. Weller

Date Published: 15th Sep 2013

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Predictive impact of MGMT promoter methylation in glioblastoma of the elderly.
GGN - German Glioma Network

Abstract (Expand)

O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter methylation identifies a subpopulation of glioblastoma patients with more favorable prognosis and predicts a benefit from alkylating agent … chemotherapy (CT). Little is known about its prevalence and clinical significance in older glioblastoma patients. We studied 233 glioblastoma patients aged 70 years or more (144 males, 89 females, median age: 74 years, range: 70.0-86.6 years), who were prospectively enrolled in the German Glioma Network, for MGMT promoter methylation by methylation-specific PCR (MSP) in all patients and DNA pyrosequencing in 166 patients. MGMT data were correlated with patient outcome. Median progression-free survival (PFS) was 4.8 months (95% CI: 4.3-5.3) and median overall survival (OS) was 7.7 months (95% CI: 6.3-9.0). MGMT promoter methylation was detected by MSP in 134 patients (57.5%). For the whole cohort, PFS was 5.2 versus 4.7 months (p = 0.207) and OS was 8.4 versus 6.4 months (p = 0.031) in patients with versus without MGMT promoter methylation. Patients with MGMT methylated tumors had longer PFS when treated with radiotherapy (RT) plus CT or CT alone compared to patients treated with RT alone. Patients with MGMT unmethylated tumors appeared to derive no survival benefit from CT, regardless of whether given at diagnosis together with RT or as a salvage treatment. Patients treated with RT plus CT or CT alone demonstrated longer OS when pyrosequencing revealed >25% MGMT methylated alleles. Taken together, MGMT promoter methylation may be a useful biomarker to stratify elderly glioblastoma patients for treatment with versus without alkylating agent CT.

Authors: G. Reifenberger, B. Hentschel, J. Felsberg, G. Schackert, M. Simon, O. Schnell, M. Westphal, W. Wick, T. Pietsch, M. Loeffler, M. Weller

Date Published: 15th Sep 2012

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Promoter methylation and expression of MGMT and the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2 in paired primary and recurrent glioblastomas.
GGN - German Glioma Network

Abstract (Expand)

Epigenetic silencing of the O(6) -methylguanine-DNA methyltransferase (MGMT) gene promoter is associated with prolonged survival in glioblastoma patients treated with temozolomide (TMZ). We investigated … whether glioblastoma recurrence is associated with changes in the promoter methylation status and the expression of MGMT and the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2 in pairs of primary and recurrent glioblastomas of 80 patients, including 64 patients treated with radiotherapy and TMZ after the first operation. Among the primary tumors, the MGMT promoter was methylated in 31 patients and unmethylated in 49 patients. In 71 patients (89%), the MGMT promoter methylation status of the primary tumor was retained at recurrence. MGMT promoter methylation, but not MGMT protein expression, was associated with longer progression-free survival, overall survival and postrecurrence survival (PRS). Moreover, PRS was increased under salvage chemotherapy. Investigation of primary and recurrent glioblastomas of 43 patients did not identify promoter methylation in any of the four MMR genes. However, recurrent glioblastomas demonstrated significantly lower MSH2, MSH6 and PMS2 protein expression as detected by immunohistochemistry. In conclusion, reduced expression of MMR proteins, but not changes in MGMT promoter methylation, is characteristic of glioblastomas recurring after the current standards of care.

Authors: J. Felsberg, N. Thon, S. Eigenbrod, B. Hentschel, M. C. Sabel, M. Westphal, G. Schackert, F. W. Kreth, T. Pietsch, M. Loffler, M. Weller, G. Reifenberger, J. C. Tonn

Date Published: 1st Aug 2011

Publication Type: Not specified

Human Diseases: glioblastoma multiforme

Patients with IDH1 wild type anaplastic astrocytomas exhibit worse prognosis than IDH1-mutated glioblastomas, and IDH1 mutation status accounts for the unfavorable prognostic effect of higher age: implications for classification of gliomas.
GGN - German Glioma Network

Abstract (Expand)

WHO grading of human brain tumors extends beyond a strictly histological grading system by providing a basis predictive for the clinical behavior of the respective neoplasm. For example, patients with … glioblastoma WHO grade IV usually show a less favorable clinical course and receive more aggressive first-line treatment than patients with anaplastic astrocytoma WHO grade III. Here we provide evidence that the IDH1 status is more prognostic for overall survival than standard histological criteria that differentiate high-grade astrocytomas. We sequenced the isocitrate dehydrogenase 1 gene (IDH1) at codon 132 in 382 patients with anaplastic astrocytoma and glioblastoma from the NOA-04 trial and from a prospective translational cohort study of the German Glioma Network. Patients with anaplastic astrocytomas carried IDH1 mutations in 60%, and patients with glioblastomas in 7.2%. IDH1 was the most prominent single prognostic factor (RR 2.7; 95% CI 1.6-4.5) followed by age, diagnosis and MGMT. The sequence from more favorable to poorer outcome was (1) anaplastic astrocytoma with IDH1 mutation, (2) glioblastoma with IDH1 mutation, (3) anaplastic astrocytoma without IDH1 mutation and (4) glioblastoma without IDH1 mutation (p < 0.0001). In this combined set of anaplastic astrocytomas and glioblastomas both, IDH1 mutation and IDH1 expression status were of greater prognostic relevance than histological diagnosis according to the current WHO classification system. Our data indicate that much of the prognostic significance of patient age is due to the predominant occurrence of IDH1 mutations in younger patients. Immunohistochemistry using a mutation-specific antibody recognizing the R132H mutation yielded similar results. We propose to complement the current WHO classification and grading of high-grade astrocytic gliomas by the IDH1 mutation status and to use this combined histological and molecular classification in future clinical trials.

Authors: C. Hartmann, B. Hentschel, W. Wick, D. Capper, J. Felsberg, M. Simon, M. Westphal, G. Schackert, R. Meyermann, T. Pietsch, G. Reifenberger, M. Weller, M. Loeffler, A. von Deimling

Date Published: 20th Nov 2010

Publication Type: Not specified

Human Diseases: brain glioma, glioblastoma multiforme

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