Reinhard Buettner

Institute for Pathology, Cologne, Köln, North Rhine-Westphalia, Germany

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Publications (554)2257.01 Total impact

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    ABSTRACT: Background Personalised medicine and targeted therapy have revolutionised cancer treatment. However, most patients develop drug resistance and relapse after showing an initial treatment response. Two theories have been postulated; either secondary resistance mutations develop de novo during therapy by mutagenesis or they are present in minor subclones prior to therapy. In this study, these two theories were evaluated in gastrointestinal stromal tumours (GISTs) where most patients develop secondary resistance mutations in the KIT gene during therapy with tyrosine kinase inhibitors. Methods We used a cohort of 33 formalin-fixed, paraffin embedded (FFPE) primary GISTs and their corresponding recurrent tumours with known mutational status. The primary tumours were analysed for the secondary mutations of the recurrences, which had been identified previously. The primary tumours were resected prior to tyrosine kinase inhibitor therapy. Three ultrasensitive, massively parallel sequencing approaches on the GS Junior (Roche, Mannheim, Germany) and the MiSeqTM (Illumina, San Diego, CA, USA) were applied. Additionally, nine fresh-frozen samples resected prior to therapy were analysed for the most common secondary resistance mutations. Results With a sensitivity level of down to 0.02%, no pre-existing resistant subclones with secondary KIT mutations were detected in primary GISTs. The sensitivity level varied for individual secondary mutations and was limited by sequencing artefacts on both systems. Artificial T > C substitutions at the position of the exon 13 p.V654A mutation, in particular, led to a lower sensitivity, independent from the source of the material. Fresh-frozen samples showed the same range of artificially mutated allele frequencies as the FFPE material. Conclusions Although we achieved a sufficiently high level of sensitivity, neither in the primary FFPE nor in the fresh-frozen GISTs we were able to detect pre-existing resistant subclones of the corresponding known secondary resistance mutations of the recurrent tumours. This supports the theory that secondary KIT resistance mutations develop under treatment by “de novo” mutagenesis. Alternatively, the detection limit of two mutated clones in 10,000 wild-type clones might not have been high enough or heterogeneous tissue samples, per se, might not be suitable for the detection of very small subpopulations of mutated cells. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1311-0) contains supplementary material, which is available to authorized users.
    BMC Cancer 12/2015; 15(1). DOI:10.1186/s12885-015-1311-0 · 3.32 Impact Factor
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    ABSTRACT: Liposarcomas (LS) are the most common malignant mesenchymal tumors, with an overall long-term mortality rate of 60%. LS comprise three major subtypes, i.e. well differentiated/dedifferentiated liposarcoma (WDLS/DDLS), myxoid/round cell liposarcoma (MLS), and pleomorphic liposarcoma (PLS). Aiming at the preclinical identification of novel therapeutic options, we here investigate the functional significance of SRC in primary human LS and in LS derived cell lines. Immunohistochemical and western blot analyses reveal relevant levels of activated p-(Tyr416)-SRC in LS of the different subtypes with particular activation in MLS and PLS. Dysregulation of the SRC modifiers CSK and PTP1B was excluded as major reason for the activation of the kinase. Consistent siRNA-mediated knockdown of SRC or inhibition by the SRC inhibitor Dasatinib led to decreased proliferation of LS cell lines of the different subtypes, with MLS cells reacting particularly sensitive in MTT assays. Flow cytometric analyses revealed that this effect was due to a significant decrease in mitotic activity and an induction of apoptosis. SRC inhibition by Dasatinib resulted in dephosphorylation of SRC itself, its interacting partners FAK and IGF-IR as well as its downstream target AKT. Consistent with a particular role of SRC in cell motility, Dasatinib reduced the migratory and invasive potential of MLS cells in Boyden chamber and matrigel chamber assays. In summary, we provide evidence that SRC activation plays an important role in LS biology and therefore represents a potential therapeutic target, particularly in MLS and PLS. This article is protected by copyright. All rights reserved. © 2015 UICC.
    International Journal of Cancer 06/2015; DOI:10.1002/ijc.29645 · 5.01 Impact Factor
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    ABSTRACT: Background High resolution molecular studies have demonstrated that the clonal acquisition of gene mutations is an important mechanism that may promote rapid disease progression and drug resistance in chronic lymphocytic leukemia (CLL). Therefore, the early and sensitive detection of such mutations is an important prerequisite for future predictive CLL diagnostics in the clinical setting. Material & Methods Here, we describe a novel, target-specific next generation sequencing (NGS) approach, which combines multiplex PCR-based target enrichment and library generation with ultra-deep high-throughput parallel sequencing using a MiSeq platform. We designed a CLL specific target panel, covering hotspots or complete coding regions of 15 genes known to be recurrently mutated and/or related to B-cell receptor signaling. Results High-throughput sequencing was performed using as little as 40 ng of peripheral blood B-cell DNA from 136 CLL patients and a dilution series of two ATM- or TP53-mutated cell lines, the latter of which demonstrated a limit of mutation detection below 5%. Using a stringent functional assessment algorithm, 102 mutations in 8 genes were identified in CLL patients, including hotspot regions of TP53, SF3B1, NOTCH1, ATM, XPO1, MYD88, DDX3X and the B-cell receptor signaling regulator PTPN6. The presence of mutations was significantly associated with an advanced disease status und molecular markers of an inferior prognosis, such as an unmutated IGHV mutation status or positivity for ZAP70 by flow cytometry. Conclusion In summary, targeted sequencing using an amplicon based library technology allows a resource-efficient and sensitive mutation analysis for diagnostic or exploratory purposes and facilitates molecular subtyping of patient sets with adverse prognosis.
    PLoS ONE 06/2015; 10(6). DOI:10.1371/journal.pone.0129544 · 3.53 Impact Factor
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    ABSTRACT: Baclground: Point mutations and small insertions/deletions (indels) in tumor relevant genes have been identified and proposed as new indicators of prognostic subsets in molecular pathology. Next generation sequencing (NGS) technologies provide the simultaneous analysis of genomic mutations in numerous target regions with high sensitivity. In the present study, multiplex PCR combined with NGS was used to establish a robust, low cost, and high sensitivity pipeline to analyse mutations of diagnostic relevant genes in prostate cancer with therapy resistance and metastases. Material & Methods: A total of more than 100 formalin-fixed and paraffin-embedded (FFPE) prostate cancer tissues including primary prostate carcinoma and the corresponding metastases, as well as prostate carcinoma from patients with transurethral resection or salvage therapy, were used for tumore macrodissection and automated DNA extraction. DNA was quantified by GeneRead quantitative PCR (Qiagen, Hilden GER) and cancer related gebe loci were amplified by multiplex PCR using primer sets designed and provided by Qiagen according to recent literature of whole exome sequencing reports. Specific barcode adapters were ligated and adapter library pools of each sample were sequenced using a MiSeq intrument platform (Illumina). Conventional Sanger sequencing served as a referenece technology. Primary data analysis and generation of fastq files was carried out by means of the MiSeq reporter program. Alignment and variant calling was performed using the CLC Cancer Workbench software (CLCbio, Qiagen). Results: We obtained a total of around 10 million reads per run. Each of the 1,837 amplicons was covered by 400 to 2,000 reads. After seperation of known single nucleotide polymorphisms (SNPs), silent mutations, and aberrations with allelic fraction <5%, mutation hotpsots in many of the 31 tumor specific genes were identified. Frequent mutations were found in TP53, the androgen receptor gene, in the epigenetic writer MLL2, as well as in the MED12 and PIK3CA genes. Conclusions: We established an easy to use, low cost, and fast pipeline of mutation analysis of a prostate cancer specific, hotspot gene panel covering the diagnostic relevant loci by a deep and highly reproducible coverage.
    99. Jahrestagung der deutschen Gesellschaft für Pathologie, Frankfurt/Main; 05/2015
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    ABSTRACT: Salivary gland cancer represents a heterogeneous group of malignant tumors. Due to their low incidence and the existence of multiple morphologically defined subtypes, these tumors are still poorly understood with regard to their molecular pathogenesis and therapeutically relevant genetic alterations. Performing a systematic and comprehensive study covering 13 subtypes of salivary gland cancer, next generation sequencing was done on 84 tissue samples of parotid gland cancer using multiplex PCR for enrichment of cancer related gene loci covering hotspots of 46 cancer genes. Mutations were identified in 22 different genes. The most frequent alterations affected TP53, followed by RAS genes, PIK3CA, SMAD4 and members of the ERB family. HRAS mutations accounted for more than 90% of RAS mutations, occurring especially in epithelial-myoepithelial carcinomas and salivary duct carcinomas. Additional mutations in PIK3CA also affected particularly epithelial-myoepithelial carcinomas and salivary duct carcinomas, occurring simultaneously with HRAS mutations in almost all cases, pointing to an unknown and therapeutically relevant molecular constellation. Interestingly, 14% of tumors revealed mutations in surface growth factor receptor genes including ALK, HER2, ERBB4, FGFR, cMET and RET, which might prove to be targetable by new therapeutic agents. 6% of tumors revealed mutations in SMAD4. In summary, our data provide novel insight into the fundamental molecular heterogeneity of salivary gland cancer, relevant in terms of tumor classification and the establishment of targeted therapeutic concepts.
    Oncotarget 05/2015; · 6.63 Impact Factor
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    ABSTRACT: Myxoid liposarcomas account for more than one third of liposarcomas and about 10% of all adult soft tissue sarcomas. The tumors are characterized by specific chromosomal translocations leading to the chimeric oncogenes FUS-DDIT3 or EWS1R-DDIT3. The encoded fusion proteins act as aberrant transcription factors. Therefore, we implemented comparative expression analyses using whole-genome microarrays in tumor and fat tissue samples. We aimed at identifying differentially expressed genes which may serve as diagnostic or prognostic biomarkers or as therapeutic targets. Microarray analyses revealed overexpression of FGFR2 and other members of the FGF/FGFR family. Overexpression of FGFR2 was validated by qPCR, immunohistochemistry and western blot analysis in primary tumor samples. Treatment of the myxoid liposarcoma cell lines MLS 402 and MLS 1765 with the FGFR inhibitors PD173074, TKI258 (dovitinib) and BGJ398 as well as specific siRNAs reduced cell proliferation, induced apoptosis and delayed cell migration. Combination of FGFR inhibitors with trabectedin further increased the effect. Our study demonstrates overexpression of FGFR2 and a functional role of FGFR signaling in myxoid liposarcoma. As FGFR inhibition showed effects on proliferation and cell migration and induced apoptosis in vitro, our data indicate the potential use of FGFR inhibitors as a targeted therapy for these tumors.
    Oncotarget 05/2015; · 6.63 Impact Factor
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    ABSTRACT: Microsatellite instability (MSI) is detected in approximately 15% of all colorectal cancers (CRC) and virtually in all cases with Lynch syndrome. The MSI phenotype is caused by dysfunctional mismatch repair (MMR) and leads to accumulation of DNA replication errors. Sporadic MSI CRC often harbours BRAF(V600E); however, no consistent data exist regarding targeted treatment approaches in BRAF(wt) MSI CRC. Mutations and quantitative MSI were analysed by deep sequencing in 196 formalin fixed paraffin embedded (FFPE) specimens comprising Lynch and Lynch-like CRCs from the German Hereditary Nonpolyposis Colorectal Cancer registry. Functional relevance of recurrent ERBB2/HER2 mutations was investigated in CRC cell lines using reversible and irreversible HER-targeting inhibitors, EGFR-directed antibody cetuximab, HER2-directed antibody trastuzumab and siRNA-mediated ERBB2/HER2 knockdown. Quantification of nucleotide loss in non-coding mononucleotide repeats distinguished microsatellite status with very high accuracy (area under curve=0.9998) and demonstrated progressive losses with deeper invasion of MMR-deficient colorectal neoplasms (p=0.008). Characterisation of BRAF(wt) MSI CRC revealed hot-spot mutations in well-known oncogenic drivers, including KRAS (38.7%), PIK3CA (36.5%), and ERBB2 (15.0%). L755S and V842I substitutions in ERBB2 were highly recurrent. Functional analyses in ERBB2-mutated MSI CRC cell lines revealed a differential response to HER-targeting compounds and superiority of irreversible pan-HER inhibitors. We developed a high-throughput deep sequencing approach for concomitant MSI and mutational analyses in FFPE specimens. We provided novel insights into clinically relevant alterations in MSI CRC and a rationale for targeting ERBB2/HER2 mutations in Lynch and Lynch-like CRC. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    Gut 04/2015; DOI:10.1136/gutjnl-2014-309026 · 13.32 Impact Factor
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    ABSTRACT: Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms, displaying variable morphological and clinicopathological features. Supportive immunohistochemical markers such as CD34, CD99, BCL2 and LSD1 are commonly applied in the differential diagnosis of SFTs, although none is sufficiently sensitive or specific enough. The aim of the present study was to examine the most differential markers for the reliable distinction of SFTs from histological mimics. We investigated the expression of STAT6, NAB2, ALDH1, GRIA2 and IGF2 in 454 comprehensive soft tissue tumors, comprising formalin-fixed paraffin-embedded (FFPE) tissue samples from 80 SFTs and 374 other mesenchymal tumors. The Duolink in situ proximity ligation assay (PLA) was adopted for the detection of NAB2-STAT6 fusion proteins. STAT6 was expressed in all 80 SFT cases with a moderate-strong nuclear staining intensity. In contrast, only 4/374 (1%) non-SFT mesenchymal tumors showed a nuclear STAT6 staining pattern. Strong expression of NAB2 and IGF2 was detected in SFT and non-SFT cases. Positive GRIA2 immunoreactivity was found in 64% (SFT) and 8% (non-SFT), respectively. Expression of ALDH1 was moderate-strong in 76% (SFT), whereas only 2 non-SFT lesions showed positive ALDH1 immunoreactivity. Moreover, the presence of NAB2‑STAT6 fusion proteins was indicated in 71/78 (91%) SFT cases by PLA. Nuclear STAT6 and cytoplasmic ALDH1 expression are the most sensitive and specific markers in the differential diagnosis of SFTs. Furthermore, application of Duolink in situ proximity ligation assay can be helpful to detect the NAB2-STAT6 fusion protein in the majority of SFTs.
    International Journal of Oncology 04/2015; DOI:10.3892/ijo.2015.2975 · 2.77 Impact Factor
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    ABSTRACT: Aberrantly expressed microRNAs (miRNAs) are involved in many diseases including cancer. In gastrointestinal stromal tumours (GISTs) expression of miR-221 and miR-222 is reduced compared to control tissue and other sarcomas but the functional effects of this downregulation are not fully understood. This study aimed at evaluating the miR-221 and miR-222 expression profiles in different GIST subtypes and the functional role of these miRNAs. Expression of miR-221 and miR-222 was analysed in six KIT exon 9 and three KIT exon 11 mutated and nine wildtype GISTs by qPCR. Viability and apoptosis were examined in three different, KIT positive GIST cell lines (GIST882, GIST-T1 and GIST48) after overexpression of these miRNAs. The modulation of KIT and the PI3K/AKT pathways was determined by Western blot. Wildtype and KIT mutated GISTs revealed reduced miRNA expression compared to adequate control tissue. miRNA expression was lower for wildtype compared to mutated GISTs. Transient transfection of miR-221 and miR-222 reduced viability and induced apoptosis by inhibition of KIT expression and its phosphorylation and activation of caspases 3 and 7 in all three GIST cell lines. p-AKT, AKT and BCL2 expression was reduced after miRNA transfection whereas only slight influence on p-MTOR, MTOR and BCL2L11 (BIM) was detected. Our results demonstrate that miR-221 and miR-222 which are downregulated in wildtype and mutated GISTs, induce apoptosis in vitro by a signalling cascade involving KIT, AKT and BCL2. Therefore, overexpression of these miRNAs seems to functionally counteract oncogenic signalling pathways in GIST. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
    Molecular Oncology 04/2015; DOI:10.1016/j.molonc.2015.03.013 · 5.94 Impact Factor
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    ABSTRACT: Multiple drug resistance (MDR), known from treating malignant tumors with chemotherapy, increases the efflux of reabsorbed reagents in tumor cells. This mechanism has been reported in the renal proximal tubule and may prevent therapeutic tubular protection in proteinuria. Since endothelin-1 (ET-1), a major component in the urine of proteinuric patients, stimulates proximal tubules, its influence on MDR was analyzed with emphasis on the multidrug resistance-associated protein 2 (MRP2), a prominent transporter in the human proximal tubule and microRNA (miRNA) 133a. ET-1 stimulated, cultured human renal proximal tubule cells (RPTECs), were analyzed via Western blot for the expression of MRP2 and via qRT-PCR for miRNA 133a. For direct interaction between the miRNA 133a and the 3'UTR of MRP2, an immunoprecipitation was performed using FITC-labelled miRNA 133a as capture, followed by MRP2 PCR analysis and Sanger sequencing. Murine Adriamycin nephropathic model and human proteinuric samples showed high levels of miRNA 133a but low levels of MRP2. The increasing miRNA 133a levels were detectable in urine samples of humans and animals. ET-1 activates the miRNA 133a, which can bind to the 3'UTR of MRP2 and is therefore responsible for the detectable decrease of MRP2. This is the first report to analyze the correlation between ET-1-induced miRNA 133a overexpression in proteinuria resulting in MRP2 downregulation, which is a contributing factor for renal cytotoxicity. The detection of the miRNA 133a in urine samples can be possibly used as a monitor for cytotoxicity. © 2015 S. Karger AG, Basel.
    American Journal of Nephrology 04/2015; 41(3):191-199. DOI:10.1159/000381272 · 2.65 Impact Factor
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    PLoS ONE 04/2015; 10(4):e0120079. DOI:10.1371/journal.pone.0120079 · 3.53 Impact Factor
  • Journal of Hepatology 04/2015; 62:S416. DOI:10.1016/S0168-8278(15)30505-5 · 10.40 Impact Factor
  • Journal of Hepatology 04/2015; 62:S428. DOI:10.1016/S0168-8278(15)30533-X · 10.40 Impact Factor
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    ABSTRACT: While recent data show that crizotinib is highly effective in patients with ROS1 rearrangement, few data is available about the prognostic impact, the predictive value for different treatments, and the genetic heterogeneity of ROS1- positive patients. 1137 patients with adenocarcinoma of the lung were analyzed regarding their ROS1 status. In positive cases, next-generation sequencing (NGS) was performed. Clinical characteristics, treatments and outcome of these patients were assessed. Overall survival (OS) was compared with genetically defined subgroups of ROS1-negative patients. 19 patients of 1035 evaluable (1.8%) had ROS1-rearrangement. The median OS has not been reached. Stage IV patients with ROS1-rearrangement had the best OS of all subgroups (36.7 months, p < 0.001). 9 of 14 (64.2%) patients had at least one response to chemotherapy. Estimated mean OS for patients receiving chemotherapy and crizotinib was 5.3 years. Ten patients with ROS1-rearrangement (52.6%) harbored additional aberrations. ROS1-rearangement is not only a predictive marker for response to crizotinib, but also seems to be the one of the best prognostic molecular markers in NSCLC reported so far. In stage IV patients, response to chemotherapy was remarkable high and overall survival was significantly better compared to other subgroups including EGFR-mutated and ALK-fusion-positive NSCLC.
    Oncotarget 03/2015; · 6.63 Impact Factor
  • Oncotarget 03/2015; · 6.63 Impact Factor
  • 03/2015; 119(3):e190-e191. DOI:10.1016/j.oooo.2014.07.390
  • 03/2015; 119(3):e178-e179. DOI:10.1016/j.oooo.2014.07.339
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    Journal of Thoracic Oncology 03/2015; DOI:10.1097/JTO.0000000000000503 · 5.80 Impact Factor
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    ABSTRACT: Background Autosomal recessive polycystic kidney disease (ARPKD) is a rare but frequently severe disorder that is typically characterized by cystic kidneys and congenital hepatic fibrosis but displays pronounced phenotypic heterogeneity. ARPKD is among the most important causes for pediatric end stage renal disease and a leading reason for liver-, kidney- or combined liver kidney transplantation in childhood. The underlying pathophysiology, the mechanisms resulting in the observed clinical heterogeneity and the long-term clinical evolution of patients remain poorly understood. Current treatment approaches continue to be largely symptomatic and opinion-based even in most-advanced medical centers. While large clinical trials for the frequent and mostly adult onset autosomal dominant polycystic kidney diseases have recently been conducted, therapeutic initiatives for ARPKD are facing the challenge of small and clinically variable cohorts for which reliable end points are hard to establish. Methods/Design ARegPKD is an international, mostly European, observational study to deeply phenotype ARPKD patients in a pro- and retrospective fashion. This registry study is conducted with the support of the German Society for Pediatric Nephrology (GPN) and the European Study Consortium for Chronic Kidney Disorders Affecting Pediatric Patients (ESCAPE Network). ARegPKD clinically characterizes long-term ARPKD courses by a web-based approach that uses detailed basic data questionnaires in combination with yearly follow-up visits. Clinical data collection is accompanied by associated biobanking and reference histology, thus setting roots for future translational research. Discussion The novel registry study ARegPKD aims to characterize miscellaneous subcohorts and to compare the applied treatment options in a large cohort of deeply characterized patients. ARegPKD will thus provide evidence base for clinical treatment decisions and contribute to the pathophysiological understanding of this severe inherited disorder.
    BMC Nephrology 02/2015; 16(1). DOI:10.1186/s12882-015-0002-z · 1.52 Impact Factor
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    ABSTRACT: Endocrine treatment regimens for breast cancer that target the estrogen receptor-α (ERα) are effective, but acquired resistance remains a limiting drawback. One mechanism of acquired resistance that has been hypothesized is functional substitution of the orphan receptor estrogen-related receptor-α (ERRα) for ERα. To examine this hypothesis, we analyzed ERRα and ERα in recurrent tamoxifen-resistant breast tumors and conducted a genome-wide target gene profiling analysis of MCF-7 breast cancer cell populations that were sensitive or resistant to tamoxifen treatment. This analysis uncovered a global redirection in the target genes controlled by ERα, ERRα, and their coactivator AIB1, defining a novel set of target genes in tamoxifen-resistant cells. Beyond differences in the ERα and ERRα target gene repertoires, both factors were engaged in similar pathobiologic processes relevant to acquired resistance. Functional analyses confirmed a requirement for ERRα in tamoxifen- and fulvestrant-resistant MCF-7 cells, with pharmacologic inhibition of ERRα sufficient to partly restore sensitivity to antiestrogens. In clinical specimens (n = 1041), increased expression of ERRα was associated with enhanced proliferation and aggressive disease parameters, including increased levels of p53 in ERα-positive cases. In addition, increased ERRα expression was linked to reduced overall survival in independent tamoxifen-treated patient cohorts. Taken together, our results suggest that ERα and ERRα cooperate to promote endocrine resistance, and they provide a rationale for the exploration of ERRα as a candidate drug target to treat endocrine-resistant breast cancer. Cancer Res; 75(4); 1-12. ©2015 AACR. ©2015 American Association for Cancer Research.
    Cancer Research 02/2015; 75(4). DOI:10.1158/0008-5472.CAN-14-0652 · 9.28 Impact Factor

Publication Stats

13k Citations
2,257.01 Total Impact Points

Institutions

  • 2011–2015
    • Institute for Pathology, Cologne
      Köln, North Rhine-Westphalia, Germany
    • Bioscientia - Institut für Medizinische Diagnostik GmbH
      Frankfurt, Hesse, Germany
  • 2010–2015
    • University of Cologne
      • • Institute of Pathology
      • • Faculty of Medicine
      Köln, North Rhine-Westphalia, Germany
    • Medical University of Varna
      Odessos, Varna, Bulgaria
  • 2013
    • Centrum für Integrierte Onkologie
      Köln, North Rhine-Westphalia, Germany
    • Universität Heidelberg
      • Institute of Papyrology
      Heidelburg, Baden-Württemberg, Germany
  • 2003–2013
    • University of Bonn
      • • Institute of Human Genetics
      • • Institute of Pathology
      Bonn, North Rhine-Westphalia, Germany
    • Johns Hopkins University
      Baltimore, Maryland, United States
    • Max Planck Institute of Biochemistry
      • Department of Molecular Medicine
      München, Bavaria, Germany
  • 2003–2011
    • University of Bonn - Medical Center
      • Institute for Clinical Chemistry and Clinical Pharmacology
      Bonn, North Rhine-Westphalia, Germany
  • 2003–2010
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany
  • 2002–2009
    • Sigmund-Freud-Institut
      Frankfurt, Hesse, Germany
  • 2008
    • Targos Molecular Pathology GmbH
      Cassel, Hesse, Germany
    • Institut für Pathologie und Molekularpathologie
      Gelsenkirchen, North Rhine-Westphalia, Germany
    • Universität des Saarlandes
      Saarbrücken, Saarland, Germany
    • University of Wuerzburg
      Würzburg, Bavaria, Germany
    • Erasmus MC
      • Department of Pathology
      Rotterdam, South Holland, Netherlands
  • 2006
    • University of Pretoria
      Πρετόρια/Πόλη του Ακρωτηρίου, Gauteng, South Africa
    • Heidelberg University
      Tiffin, Ohio, United States
  • 2005
    • Georg-August-Universität Göttingen
      Göttingen, Lower Saxony, Germany
  • 2000–2005
    • University Hospital RWTH Aachen
      Aachen, North Rhine-Westphalia, Germany
    • University of California, San Francisco
      • Department of Neurological Surgery
      San Francisco, California, United States
    • Geisel School of Medicine at Dartmouth
      • Norris Cotton Cancer Center
      Hanover, New Hampshire, United States
  • 2004
    • Klinikum Kassel
      Cassel, Hesse, Germany
    • Università degli Studi di Palermo
      Palermo, Sicily, Italy
  • 2000–2002
    • RWTH Aachen University
      • Institute of Pathology
      Aachen, North Rhine-Westphalia, Germany
  • 1997–2001
    • Universität Regensburg
      • • Department of Dermatology and Venereology
      • • Institut für Psychologie
      Ratisbon, Bavaria, Germany
  • 1993–2000
    • University Hospital Regensburg
      • • Institut für Pathologie
      • • Klinik für Dermatologie
      Ratisbon, Bavaria, Germany
  • 1991–1994
    • University of Texas MD Anderson Cancer Center
      Houston, Texas, United States