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  • 1
    Keywords: GENE-EXPRESSION ; DIFFERENTIATION ; BREAST-CANCER ; REPRODUCIBILITY ; PROSTATE-CANCER ; SIGNATURE ; RISK STRATIFICATION ; transcriptome ; EXPRESSION-BASED CLASSIFICATION ; NEUROBLASTOMA PATIENTS
    Abstract: BACKGROUND: Gene expression profiling is being widely applied in cancer research to identify biomarkers for clinical endpoint prediction. Since RNA-seq provides a powerful tool for transcriptome-based applications beyond the limitations of microarrays, we sought to systematically evaluate the performance of RNA-seq-based and microarray-based classifiers in this MAQC-III/SEQC study for clinical endpoint prediction using neuroblastoma as a model. RESULTS: We generate gene expression profiles from 498 primary neuroblastomas using both RNA-seq and 44 k microarrays. Characterization of the neuroblastoma transcriptome by RNA-seq reveals that more than 48,000 genes and 200,000 transcripts are being expressed in this malignancy. We also find that RNA-seq provides much more detailed information on specific transcript expression patterns in clinico-genetic neuroblastoma subgroups than microarrays. To systematically compare the power of RNA-seq and microarray-based models in predicting clinical endpoints, we divide the cohort randomly into training and validation sets and develop 360 predictive models on six clinical endpoints of varying predictability. Evaluation of factors potentially affecting model performances reveals that prediction accuracies are most strongly influenced by the nature of the clinical endpoint, whereas technological platforms (RNA-seq vs. microarrays), RNA-seq data analysis pipelines, and feature levels (gene vs. transcript vs. exon-junction level) do not significantly affect performances of the models. CONCLUSIONS: We demonstrate that RNA-seq outperforms microarrays in determining the transcriptomic characteristics of cancer, while RNA-seq and microarray-based models perform similarly in clinical endpoint prediction. Our findings may be valuable to guide future studies on the development of gene expression-based predictive models and their implementation in clinical practice.
    Type of Publication: Journal article published
    PubMed ID: 26109056
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  • 2
    Publication Date: 2018-12-07
    Description: Neuroblastoma is a pediatric tumor of the sympathetic nervous system. Its clinical course ranges from spontaneous tumor regression to fatal progression. To investigate the molecular features of the divergent tumor subtypes, we performed genome sequencing on 416 pretreatment neuroblastomas and assessed telomere maintenance mechanisms in 208 of these tumors. We found that patients whose tumors lacked telomere maintenance mechanisms had an excellent prognosis, whereas the prognosis of patients whose tumors harbored telomere maintenance mechanisms was substantially worse. Survival rates were lowest for neuroblastoma patients whose tumors harbored telomere maintenance mechanisms in combination with RAS and/or p53 pathway mutations. Spontaneous tumor regression occurred both in the presence and absence of these mutations in patients with telomere maintenance–negative tumors. On the basis of these data, we propose a mechanistic classification of neuroblastoma that may benefit the clinical management of patients.
    Keywords: Medicine, Diseases
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Keywords: CANCER ; EXPRESSION ; Germany ; RISK ; GENE ; GENE-EXPRESSION ; GENES ; TUMORS ; PROGRESSION ; PATTERNS ; gene expression ; genetics ; DELETIONS ; REGION ; PHENOTYPE ; MICROARRAY ANALYSIS ; METHYLATION ; neuroblastoma ; ONCOLOGY ; PATTERN ; CANDIDATE GENES ; DNA COPY NUMBER ; SUBTYPES ; EXPRESSION PROFILES ; HIGH-RESOLUTION ANALYSIS ; SUBGROUPS ; outcome ; CELL BIOLOGY ; Genetic ; 4S NEUROBLASTOMA ; integrative genomics ; loss of 11q
    Abstract: Imbalances in chromosome 11q occur in approximately 30% of primary neuroblastoma and are associated with poor outcome. It has been suggested that 11q loss constitutes a distinct clinico-genetic neuroblastoma subgroup by affecting expression levels of corresponding genes. This study analysed the relationship of 11q loss, clinical phenotype and global transcriptomic profiles in four clinico-genetic subgroups (11q alteration/favourable outcome, n = 7; 11q alteration/unfavourable outcome, n 14; no 11q alteration/favourable outcome, n 81; no 11q alteration/unfavourable outcome, n 8; tumours with MYCN amplification and/or 1p loss were excluded). Unsupervised and supervised comparisons of gene expression profiles consistently showed significantly different mRNA patterns between favourable and unfavourable neuroblastomas, both in the subgroups with and without 11q loss. In contrast, favourable tumours with and without 11q loss showed highly similar transcriptomic profiles. Disproportionate downregulation of 11q genes was observed only in unfavourable tumours with 11q loss. The diverging molecular profiles were neither caused by considerable differences in the size of the deleted regions nor by differential methylation patterns of 11q genes. Together, this study shows that neuroblastoma with 11q loss comprises two biological subgroups that differ both in their clinical phenotype and gene expression patterns, indicating that 11q loss is not a primary determinant of neuroblastoma tumour behaviour. Oncogene (2010) 29, 865-875; doi:10.1038/onc.2009.390; published online 9 November 2009
    Type of Publication: Journal article published
    PubMed ID: 19901960
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  • 4
    Keywords: CANCER ; EXPRESSION ; CLASSIFICATION ; QUANTIFICATION ; GENE ; GENE-EXPRESSION ; TUMORS ; PATTERNS ; PATHOGENESIS ; REVEALS ; PREDISPOSITION ; ANAPLASTIC LYMPHOMA KINASE ; ACTIVATING MUTATIONS
    Abstract: Purpose: Genomic alterations of the anaplastic lymphoma kinase (ALK) gene have been postulated to contribute to neuroblastoma pathogenesis. This study aimed to determine the interrelation of ALK mutations, ALK expression levels, and clinical phenotype in primary neuroblastoma. Experimental Design: The genomic ALK status and global gene expression patterns were examined in 263 primary neuroblastomas. Allele-specific ALK expression was determined by cDNA cloning and sequencing. Associations of genomic ALK alterations and ALK expression levels with clinical phenotypes and transcriptomic profiles were compared. Results: Nonsynonymous point mutations of ALK were detected in 21 of 263 neuroblastomas (8%). Tumors with ALK mutations exhibited about 2-fold elevated median ALK mRNA levels in comparison with tumors with wild-type (WT) ALK. Unexpectedly, the WT allele was preferentially expressed in 12 of 21 mutated tumors. Whereas survival of patients with ALK mutated tumors was significantly worse as compared with the entire cohort of WT ALK patients, it was similarly poor in patients with WT ALK tumors in which ALK expression was as high as in ALK mutated neuroblastomas. Global gene expression patterns of tumors with ALK mutations or with high-level WT ALK expression were highly similar, and suggested that ALK may be involved in cellular proliferation in primary neuroblastoma. Conclusions: Primary neuroblastomas with mutated ALK exhibit high ALK expression levels and strongly resemble neuroblastomas with elevated WT ALK expression levels in both their clinical and molecular phenotypes. These data suggest that high levels of mutated and WT ALK mediate similar molecular functions that may contribute to a malignant phenotype in primary neuroblastoma.
    Type of Publication: Journal article published
    PubMed ID: 21632861
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  • 5
    Keywords: RECEPTOR ; CANCER ; GENES ; ASSOCIATION ; PHENOTYPE ; HETEROGENEITY ; N-MYC ; SIGNATURES ; ALK ; DNA METHYLATION DATA
    Abstract: Neuroblastoma is a malignancy of the developing sympathetic nervous system that is often lethal when relapse occurs. We here used whole-exome sequencing, mRNA expression profiling, array CGH and DNA methylation analysis to characterize 16 paired samples at diagnosis and relapse from individuals with neuroblastoma. The mutational burden significantly increased in relapsing tumors, accompanied by altered mutational signatures and reduced subclonal heterogeneity. Global allele frequencies at relapse indicated clonal mutation selection during disease progression. Promoter methylation patterns were consistent over disease course and were patient specific. Recurrent alterations at relapse included mutations in the putative CHD5 neuroblastoma tumor suppressor, chromosome 9p losses, DOCK8 mutations, inactivating mutations in PTPN14 and a relapse-specific activity pattern for the PTPN14 target YAP. Recurrent new mutations in HRAS, KRAS and genes mediating cell-cell interaction in 13 of 16 relapse tumors indicate disturbances in signaling pathways mediating mesenchymal transition. Our data shed light on genetic alteration frequency, identity and evolution in neuroblastoma.
    Type of Publication: Journal article published
    PubMed ID: 26121086
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  • 6
    Keywords: GENE ; neuroblastoma ; ENHANCERS ; LANDSCAPE ; TERT REARRANGEMENTS
    Abstract: Neuroblastoma is a malignant paediatric tumour of the sympathetic nervous system. Roughly half of these tumours regress spontaneously or are cured by limited therapy. By contrast, high-risk neuroblastomas have an unfavourable clinical course despite intensive multimodal treatment, and their molecular basis has remained largely elusive. Here we have performed whole-genome sequencing of 56 neuroblastomas (high-risk, n = 39; low-risk, n = 17) and discovered recurrent genomic rearrangements affecting a chromosomal region at 5p15.33 proximal of the telomerase reverse transcriptase gene (TERT). These rearrangements occurred only in high-risk neuroblastomas (12/39, 31%) in a mutually exclusive fashion with MYCN amplifications and ATRX mutations, which are known genetic events in this tumour type. In an extended case series (n = 217), TERT rearrangements defined a subgroup of high-risk tumours with particularly poor outcome. Despite a large structural diversity of these rearrangements, they all induced massive transcriptional upregulation of TERT. In the remaining high-risk tumours, TERT expression was also elevated in MYCN-amplified tumours, whereas alternative lengthening of telomeres was present in neuroblastomas without TERT or MYCN alterations, suggesting that telomere lengthening represents a central mechanism defining this subtype. The 5p15.33 rearrangements juxtapose the TERT coding sequence to strong enhancer elements, resulting in massive chromatin remodelling and DNA methylation of the affected region. Supporting a functional role of TERT, neuroblastoma cell lines bearing rearrangements or amplified MYCN exhibited both upregulated TERT expression and enzymatic telomerase activity. In summary, our findings show that remodelling of the genomic context abrogates transcriptional silencing of TERT in high-risk neuroblastoma and places telomerase activation in the centre of transformation in a large fraction of these tumours.
    Type of Publication: Journal article published
    PubMed ID: 26466568
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  • 7
    Keywords: STAGE ; PROGRESSION ; AMPLIFICATION ; chemotherapy ; DELETIONS ; SPONTANEOUS REGRESSION ; PREDICTION ; pathology ; N-MYC ; EXPRESSION-BASED CLASSIFICATION
    Abstract: Purpose: To optimize neuroblastoma treatment stratification, we aimed at developing a novel risk estimation system by integrating gene expression-based classification and established prognostic markers. Material and Methods: Gene expression profiles were generated from 709 neuroblastoma specimens using customized 4x44K microarrays. Classification models were built using 75 tumors with contrasting courses of disease. Validation was performed in an independent test set (n=634) by Kaplan-Meier estimates and Cox regression analyses. Results: The best-performing classifier predicted patient outcome with an accuracy of 0.95 (sensitivity 0.93, specificity 0.97) in the validation cohort. The highest potential clinical value of this predictor was observed for current low-risk patients (LR: 5-year EFS 0.84+/-0.02 vs 0.29+/-0.10; 5-year OS 0.99+/-0.01vs 0.76+/-0.11; both p〈0.001) and intermediate-risk patients (IR: 5-year EFS 0.88+/-0.06 vs 0.41+/-0.10; 5-year OS 1.0 vs 0.70+/-0.09; both p〈0.001). In multivariate Cox regression models for LR/IR patients the classifier outperformed risk assessment of the current German trial NB2004 (EFS: HR 5.07, 95%-CI 3.20-8.02, OS: HR 25.54, 95%-CI 8.40-77.66; both p〈0.001). Based on these findings, we propose to integrate the classifier into a revised risk stratification system for LR/IR patients. According to this system, we identified novel subgroups with poor outcome (5-year EFS 0.19+/-0.08; 5-year OS 0.59+/-0.1), for whom we propose intensified treatment, and with beneficial outcome (5-year EFS 0.87+/-0.05; 5-year OS 1.0), who may benefit from treatment de-escalation. Conclusion: Combination of gene expression-based classification and established prognostic markers improves risk estimation of LR/IR neuroblastoma patients. We propose to implement our revised treatment stratification system in a prospective clinical trial.
    Type of Publication: Journal article published
    PubMed ID: 25231397
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  • 8
    Keywords: tumor ; Germany ; PATHWAY ; PATHWAYS ; CLASSIFICATION ; DISEASE ; RISK ; GENE-EXPRESSION ; microarray ; TUMORS ; ACCURACY ; PATIENT ; MARKER ; PROGRESSION ; COMPARATIVE GENOMIC HYBRIDIZATION ; gene expression ; MUTATION ; TUMOR PROGRESSION ; TUMOR-SUPPRESSOR GENE ; SIGNALING PATHWAY ; SIGNALING PATHWAYS ; MUTATIONS ; CHILDREN ; BEHAVIOR ; neuroblastoma ; N-MYC ; signaling ; review ; GENE-EXPRESSION PROFILES ; ACCURATE ; MOLECULAR CLASSIFICATION ; STAGE NEUROBLASTOMA ; ARRAY-CGH ; outcome ; CHROMOSOME ARM 17Q ; pediatric oncology ; HIGH-RISK NEUROBLASTOMAS ; Genetic ; therapeutic ; STRATEGY ; 4S NEUROBLASTOMA ; CHILDRENS ONCOLOGY GROUP ; embryonal tumors ; METASTATIC NEUROBLASTOMA ; oncogenomics
    Abstract: For many decades, neuroblastoma has remained a challenging disease for both clinicians and researchers. Now, techniques that efficiently specify both comprehensive genetic and gene-expression alterations of neuroblastoma tumors have provided molecular markers that indicate tumor behavior and patient outcome with very high accuracy, Once the anticipated value of these markers has been confirmed in ongoing studies, patients may profit from more accurate risk assessment by integrating these markers into clinical routine. Moreover, disclosing further tumor-initiating events, such as the recently revealed oncogenic mutations of ALK, will further promote the elucidation of the genetic etiology of the disease. Together with recent information on altered signaling pathways in aggressively growing tumors, this knowledge will help to establish therapeutic strategies specifically targeting molecular key factors of neuroblastoma tumor progression
    Type of Publication: Journal article published
    PubMed ID: 19519203
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  • 9
    Keywords: EXPRESSION ; SURVIVAL ; Germany ; MODEL ; MODELS ; CLASSIFICATION ; DIAGNOSIS ; COHORT ; DEATH ; DISEASE ; MORTALITY ; RISK ; GENE ; GENE-EXPRESSION ; microarray ; PATIENT ; MARKER ; IMPACT ; STAGE ; AMPLIFICATION ; gene expression ; microarrays ; AGE ; MARKERS ; HIGH-RISK ; STRATEGIES ; SPONTANEOUS REGRESSION ; PREDICTION ; INFANTS ; pathology ; CHILDREN ; MICROARRAY ANALYSIS ; neuroblastoma ; ONCOLOGY ; REGRESSION ; overall survival ; INDEPENDENT PROGNOSTIC MARKER ; methods ; PROGNOSTIC MARKER ; PROFILES ; EXPRESSION PROFILES ; RISK STRATIFICATION ; SUBGROUPS ; MYC ; PROFILE ; outcome ; STRATEGY ; CONTRIBUTE ; COHORTS ; COX REGRESSION ; clinical oncology ; STRATIFICATION ; prognostic
    Abstract: Purpose To evaluate the impact of a predefined gene expression - based classifier for clinical risk estimation and cytotoxic treatment decision making in neuroblastoma patients. Patients and Methods Gene expression profiles of 440 internationally collected neuroblastoma specimens were investigated by microarray analysis, 125 of which were examined prospectively. Patients were classified as either favorable or unfavorable by a 144- gene prediction analysis for microarrays (PAM) classifier established previously on a separate set of 77 patients. PAM classification results were compared with those of current prognostic markers and risk estimation strategies. Results The PAM classifier reliably distinguished patients with contrasting clinical courses (favorable [n = 249] and unfavorable [n = 191]; 5- year event free survival [EFS] 0.84 +/- 0.03 v 0.38 +/- 0.04; 5-year overall survival [OS] 0.98 +/- 0.01 v 0.56 +/- 0.05, respectively; both P = .001). Moreover, patients with divergent outcome were robustly discriminated in both German and international cohorts and in prospectively analyzed samples (P = .001 for both EFS and OS for each). In subgroups with clinical low-, intermediate-, and high-risk of death from disease, the PAM predictor significantly separated patients with divergent outcome (low-risk 5-year OS: 1.0 v 0.75 +/- 0.10, P = .001; intermediaterisk: 1.0 v 0.82 +/- 0.08, P = .042; and high-risk: 0.81 +/- 0.08 v 0.43 = 0.05, P=.001). In multivariate Cox regression models based on both EFS and OS, PAM was a significant independent prognostic marker (EFS: hazard ratio [HR], 3.375; 95% CI, 2.075 to 5.492; P=.001; OS: HR, 11.119, 95% CI, 2.487 to 49.701; P=.001). The highest potential clinical impact of the classifier was observed in patients currently considered as non - high- risk (n= 289; 5- year EFS: 0.87= 0.02 v 0.44= 0.07; 5- year OS: 1.0 v 0.80= 0.06; both P=.001). Conclusion Gene expression - based classification using the 144- gene PAM predictor can contribute to improved treatment stratification of neuroblastoma patients
    Type of Publication: Journal article published
    PubMed ID: 20567016
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  • 10
    Keywords: APOPTOSIS ; CANCER ; EXPRESSION ; SITES ; GENE-EXPRESSION ; cell line ; DIFFERENTIATION ; NEUROBLASTOMA-CELLS ; CLEAVAGE ; AMPLIFICATION ; REGIONS ; DNA-DAMAGE ; REVEALS ; TUMOR-SUPPRESSOR ; senescence ; miRNA ; 3p25.3 ; p53 stabilization
    Abstract: Several microRNA (miRNA) loci are found within genomic regions frequently deleted in primary neuroblastoma, including miR-885-5p at 3p25.3. In this study, we demonstrate that miR-885-5p is downregulated on loss of 3p25.3 region in neuroblastoma. Experimentally enforced miR-885-5p expression in neuroblastoma cell lines inhibits proliferation triggering cell cycle arrest, senescence and/or apoptosis. miR-885-5p leads to the accumulation of p53 protein and activates the p53 pathway, resulting in upregulation of p53 targets. Enforced miR-885-5p expression consistently leads to downregulation of cyclin-dependent kinase (CDK2) and mini-chromosome maintenance protein (MCM5). Both genes are targeted by miR-885-5p via predicted binding sites within the 3'-untranslated regions (UTRs) of CDK2 and MCM5. Transcript profiling after miR-885-5p introduction in neuroblastoma cells reveals alterations in expression of multiple genes, including several p53 target genes and a number of factors involved in p53 pathway activity. Taken together, these data provide evidence that miR-885-5p has a tumor suppressive role in neuroblastoma interfering with cell cycle progression and cell survival.
    Type of Publication: Journal article published
    PubMed ID: 21233845
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