Ali Fuat Okuducu

DNA methylation-based classification and grading system for meningioma: a multicentre, retrospective analysis

BACKGROUNDnThe WHO classification of brain tumours describes 15 subtypes of meningioma. Nine of these subtypes are allotted to WHO grade I, and three each to grade II and grade III. Grading is based solely on histology, with an absence of molecular markers. Although the existing classification and grading approach is of prognostic value, it harbours shortcomings such as ill-defined parameters for subtypes and grading criteria prone to arbitrary judgment. In this study, we aimed for a comprehensive characterisation of the entire molecular genetic landscape of meningioma to identify biologically and clinically relevant subgroups.nnnMETHODSnIn this multicentre, retrospective analysis, we investigated genome-wide DNA methylation patterns of meningiomas from ten European academic neuro-oncology centres to identify distinct methylation classes of meningiomas. The methylation classes were further characterised by DNA copy number analysis, mutational profiling, and RNA sequencing. Methylation classes were analysed for progression-free survival outcomes by the Kaplan-Meier method. The DNA methylation-based and WHO classification schema were compared using the Brier prediction score, analysed in an independent cohort with WHO grading, progression-free survival, and disease-specific survival data available, collected at the Medical University Vienna (Vienna, Austria), assessing methylation patterns with an alternative methylation chip.nnnFINDINGSnWe retrospectively collected 497 meningiomas along with 309 samples of other extra-axial skull tumours that might histologically mimic meningioma variants. Unsupervised clustering of DNA methylation data clearly segregated all meningiomas from other skull tumours. We generated genome-wide DNA methylation profiles from all 497 meningioma samples. DNA methylation profiling distinguished six distinct clinically relevant methylation classes associated with typical mutational, cytogenetic, and gene expression patterns. Compared with WHO grading, classification by individual and combined methylation classes more accurately identifies patients at high risk of disease progression in tumours with WHO grade I histology, and patients at lower risk of recurrence among WHO grade II tumours (p=0·0096) from the Brier prediction test). We validated this finding in our independent cohort of 140 patients with meningioma.nnnINTERPRETATIONnDNA methylation-based meningioma classification captures clinically more homogenous groups and has a higher power for predicting tumour recurrence and prognosis than the WHO classification. The approach presented here is potentially very useful for stratifying meningioma patients to observation-only or adjuvant treatment groups. We consider methylation-based tumour classification highly relevant for the future diagnosis and treatment of meningioma.nnnFUNDINGnGerman Cancer Aid, Else Kröner-Fresenius Foundation, and DKFZ/Heidelberg Institute of Personalized Oncology/Precision Oncology Program.

TERT Promoter Mutations and Risk of Recurrence in Meningioma

The World Health Organization (WHO) classification and grading system attempts to predict the clinical course of meningiomas based on morphological parameters. However, because of high interobserver variation of some criteria, more reliable prognostic markers are required. Here, we assessed the TERT promoter for mutations in the hotspot regions C228T and C250T in meningioma samples from 252 patients. Mutations were detected in 16 samples (6.4% across the cohort, 1.7%, 5.7%, and 20.0% of WHO grade I, II, and III cases, respectively). Data were analyzed by t test, Fishers exact test, log-rank test, and Cox proportional hazard model. All statistical tests were two-sided. Within a mean follow-up time in surviving patients of 68.1 months, TERT promoter mutations were statistically significantly associated with shorter time to progression (P < .001). Median time to progression among mutant cases was 10.1 months compared with 179.0 months among wild-type cases. Our results indicate that the inclusion of molecular data (ie, analysis of TERT promoter status) into a histologically and genetically integrated classification and grading system for meningiomas increases prognostic power. Consequently, we propose to incorporate the assessment of TERT promoter status in upcoming grading schemes for meningioma.

EGFR and erbB2 in malignant peripheral nerve sheath tumors and implications for targeted therapy

Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas with poor prognosis and limited treatment options. Evidence for a role of epidermal growth factor receptor (EGFR) and receptor tyrosine kinase erbB2 in MPNSTs led us to systematically study these potential therapeutic targets in a larger tumor panel (n = 37). Multiplex ligation-dependent probe amplification and fluorescence in situ hybridization analysis revealed increased EGFR dosage in 28% of MPNSTs. ERBB2 and three tumor suppressor genes (PTEN [phosphatase and tensin homolog deleted on chromosome 10], CDKN2A [cyclin-dependent kinase inhibitor 2A], and TP53 [tumor protein p53]) were frequently lost or reduced. Reduction of CDKN2A was linked to appearance of metastasis. Comparison of corresponding neurofibromas and MPNSTs revealed an increase in genetic lesions in MPNSTs. No somatic mutations were found within tyrosine-kinase-encoding exons of EGFR and ERBB2. However, at the protein level, expression of EGFR and erbB2 was frequently detected in MPNSTs. EGFR expression was significantly associated with increased EGFR gene dosage. The EGFR ligands transforming growth factor alpha and EGF were more strongly expressed in MPNSTs than in neurofibromas. The effects of the drugs erlotinib and trastuzumab, which target EGFR and erbB2, were determined on MPNST cell lines. In contrast to trastuzumab, erlotinib mediated dose-dependent inhibition of cell proliferation. EGF-induced EGFR phosphorylation was attenuated by erlotinib. Summarized, our data indicate that EGFR and erbB2 are potential targets in treatment of MPNST patients.

Methylation-based classification of benign and malignant peripheral nerve sheath tumors

AbstractThe vast majority of peripheral nerve sheath tumors derive from the Schwann cell lineage and comprise diverse histological entities ranging from benign schwannomas and neurofibromas to high-grade malignant peripheral nerve sheath tumors (MPNST), each with several variants. nThere is increasing evidence for methylation profiling being able to delineate biologically relevant tumor groups even within the same cellular lineage. Therefore, we used DNA methylation arrays for methylome- and chromosomal profile-based characterization of 171 peripheral nerve sheath tumors. We analyzed 28 conventional high-grade MPNST, three malignant Triton tumors, six low-grade MPNST, four epithelioid MPNST, 33 neurofibromas (15 dermal, 8 intraneural, 10 plexiform), six atypical neurofibromas, 43 schwannomas (including 5 NF2 and 5 schwannomatosis associated cases), 11 cellular schwannomas, 10 melanotic schwannomas, 7 neurofibroma/schwannoma hybrid tumors, 10 nerve sheath myxomas and 10 ganglioneuromas. Schwannomas formed different epigenomic subgroups including a vestibular schwannoma subgroup. Cellular schwannomas were not distinct from conventional schwannomas. Nerve sheath myxomas and neurofibroma/schwannoma hybrid tumors were most similar to schwannomas. Dermal, intraneural and plexiform neurofibromas as well as ganglioneuromas all showed distinct methylation profiles. Atypical neurofibromas and low-grade MPNST were indistinguishable with a common methylation profile and frequent losses of CDKN2A. Epigenomic analysis finds two groups of conventional high-grade MPNST sharing a frequent loss of neurofibromin. The larger of the two groups shows an additional loss of trimethylation of histone H3 at lysine 27 (H3K27me3). The smaller one retains H3K27me3 and is found in spinal locations. Sporadic MPNST with retained neurofibromin expression did not form an epigenetic group and most cases could be reclassified as cellular schwannomas or soft tissue sarcomas. Widespread immunohistochemical loss of H3K27me3 was exclusively seen in MPNST of the main methylation cluster, which defines it as an additional useful marker for the differentiation of cellular schwannoma and MPNST.

The Evolution of Our Understanding on Glioma

The description of neuroglia by Virchow in 1848 may be considered the starting point of our understanding of primary brain tumors. At the beginning of the 20th century, surgical removal of primary brain tumors became possible, and therefore, tissue for microscopic analysis and clinical data on survival became available. During this time, research on gliomas beyond improving surgical procedures focused on their classification. The classification schemes developed emphasized parameters for sorting tumors with regard to (i) cytological aspects; (ii) presumed tumor cell origin; (iii) histological appearance of the tissue; or (iv) clinical outcome. Over the years, experimental studies have greatly improved our knowledge on gliomas. Gliomas induced by viruses, chemicals, radiation, transgenes and knock‐out technology contributed to the understanding of their pathogenesis and still serve as preclinical models for the testing of novel therapies. Recent advances in developmental neurobiology and the identification of stem cells provided new insights into the origin of brain tumors and the molecular mechanisms of tumor formation. This review briefly compiles the evolution of our concepts on gliomas, focusing on the latest developments.

Increased expression of avian erythroblastosis virus E26 oncogene homolog 1 in World Health Organization grade 1 meningiomas is associated with an elevated risk of recurrence and is correlated with the expression of its target genes matrix metalloproteinase‐2 and MMP‐9

The transcription factor avian erythroblastosis virus E26 (V‐Ets) oncogene homolog 1 (Ets‐1) is involved in tumor development and progression through the transcriptional regulation of several matrix‐degrading enzyme systems, including matrix metalloproteinases (MMPs). It has been demonstrated that the MMPs are expressed strongly in high‐grade meningiomas. To determine the biologic significance of Ets‐1 in the progression of benign meningiomas, the authors investigated the expressions of Ets‐1 and its target genes MMP‐2 and MMP‐9 in primary and recurrent, Grade 1 meningiomas.

Ets‐1 is up‐regulated together with its target gene products matrix metalloproteinase‐2 and matrix metalloproteinase‐9 in atypical and anaplastic meningiomas

Aims :u2002Matrix metalloproteinases (MMPs) are a pivotal enzyme system involved in extracellular matrix (ECM) degradation and are considered to be important in the development and invasion of human tumours. Little is known about the regulation of MMPs in meningioma development and prognosis. The transcription factor Ets‐1 is the main regulator of several MMPs, including MMP‐2 and ‐9. The aim of this study was to determine the relationship between the expression of Ets‐1, MMP‐2 and ‐9 and the malignant potential of meningiomas.

The transcription factor Ets-1 is expressed in human amniochorionic membranes and is up-regulated in term and preterm premature rupture of membranes.

Abstract Objective: The major tensile strength of fetal membranes is provided by their extracellular matrix (ECM) components. The transcription factor Ets-1 is a critical mediator of ECM remodelling. The purpose of this study was to examine whether Ets-1 is expressed in human fetal membranes and whether it is implicated in premature membrane rupture. Study design: Amniochorionic membranes from 52 women in the following categories were analyzed for Ets-1 expression: preterm and term premature rupture of membranes, preterm and term labor and delivery, and preterm and term cesarean sections without previous onset of labor. Ets-1 protein was localized with the use of immunohistochemistry. Ets-1 levels were determined with a histoscore. Results: Ets-1 protein was localized to the trophoblast as well as to the stromal layers. Ets-1 protein expression was up-regulated in the stroma of term and preterm prematurely ruptured membranes. Conclusion: Ets-1 is expressed in human fetal membranes and its expression is up-regulated with premature rupture of membranes, suggesting a role for Ets-1 in ECM remodelling of the membranes.

Hemosiderin deposits in chronic graft‐vs.‐host disease related myopathy

Abstract:u2002 Chronic graft‐vs.‐host disease (cGVHD) occurs in 20–50% of patients who survive for at least 100u2003d after allogeneic stem cell transplantation (SCT). cGVHD includes scleroderma‐like skin changes, chronic cholangitis, obstructive lung disease and general wasting syndrome. Polymyositis or myopathy are rare manifestations of cGVHD with approximately 40 reported cases. Polymyositis accompanied by hemosiderin deposits in cGVHD has been reported only once, and there are no reports on lipofuscin deposits in skeletal muscle cells in cGVHD. We report here on a 56‐yr‐old male who underwent allogeneic SCT in 1999 for osteomyelofibrosis and progressive hematopoietic insufficiency. In February 2004, the patient was hospitalized for progressive muscular weakness with loss of the ability to walk. Laboratory tests demonstrated normal values for serum creatine kinase, aldolase and lactic dehydrogenase; the ferritin level was highly elevated. The femoral muscle biopsy showed mostly perifascicular atrophy as well as numerous subsarcolemmal hemosiderin and lipofuscin deposits. Intravenous administration of the chelating agent deferoxamine was ineffective. Three weeks later the patient died of aspiration pneumonia. Interestingly, autopsy disclosed moderate hemosiderin deposits in the liver, the organ usually involved in hemosiderosis.