Reinhard Buettner

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

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Publications (543)2172.84 Total impact

  • [Show abstract] [Hide abstract]
    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
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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
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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
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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
  • PLoS ONE 04/2015; 10(4):e0120079. DOI:10.1371/journal.pone.0120079
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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;
  • Oncotarget 03/2015;
  • 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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    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
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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
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    ABSTRACT: This study examines the expression and the role of four-and-a-half LIM domains protein 2 (FHL2) and transforming growth factor β1 (TGF-β1) in human malignant melanoma. It is determined whether both proteins influence melanoma survival time. We analyzed the immunohistochemical staining intensities of FHL2 and TGF-β1 in normal skin and in 50 malignant melanomas with different mutation status (BRAF-V600E, NRAS codon 61 mutation, and wild type). Survival data were available for 45 cases. In melanocytes of nonneoplastic human skin, FHL2 expression was absent. In contrast, 38 (76%) of 50 melanomas showed strong cytoplasmic and partly nuclear FHL2 expression. At the invasion front, cytoplasmic TGF-β1 staining was observed in 32 (64%) of 50 melanomas, and a correlation of FHL2 and TGF-β1 staining intensities was detectable. In follow-up analyses, enhanced FHL2 and TGF-β1 staining intensities in the tumor invasion front were associated with poor survival. Enhanced FHL2 and TGF-β1 expression is correlated with poor survival in human malignant melanoma. Protumorigenic effects of autocrine TGF-β1 secretion might be exerted by induction of FHL2 expression in melanoma cells. Since melanomas treated with targeted therapies often do not show sufficient response rates, inhibition of FHL2 and/or TGF-β1 might be a promising therapeutic approach. Copyright© by the American Society for Clinical Pathology.
    American Journal of Clinical Pathology 02/2015; 143(2):248-56. DOI:10.1309/AJCPXEC6CIT2TXAF
  • Zeitschrift für Gastroenterologie 01/2015; 53(01). DOI:10.1055/s-0034-1397089
  • Zeitschrift für Gastroenterologie 01/2015; 53(01). DOI:10.1055/s-0034-1397082
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    ABSTRACT: Hepatocellular carcinoma (HCC) are highly malignant tumors triggered by a wide variety of genetic alterations. Importantly, they show multicentric occurrence characterized by a nodule-in-nodule pattern. In the present study, we investigate the occurrence of disease related nuclear mutations and whole mitochondrial genomic variants by a comprehensive ultra-deep sequencing approach as a novel tool for hepatocellular cancer follow-up and prognosis. Macrodissected 48 HCC nodules, representing different tumor grades, and adjacent non-cancerous tissues from HCC patients were studied. Hot spot mutation screening of nuclear DNA (nDNA) was performed using a multiplex PCR approach covering 40 disease relevant gene regions by a total of 394 amplicons. The mitochondrial (mt) genome is highly susceptible to DNA alterations due to the lack of protective histones and a limited repair system. Therefore, we were using mt-variations as a way of focal cancer barcoding and tracking. Thus, 108 primer sets spanning the whole mtDNA were designed and automatic single PCR set-up was established using the Biomek robotic system. Target enriched libraries of mtDNA and nDNA were sequenced by means of the MiSeq platform and data analysis was performed by the CLC Cancer Research Workbench. Whole mt-genome analysis revealed high frequency of variants in the D-Loop region and the MT-CYB gene. In particular, in HCC nodules of non-cirrhotic origin a wide spectrum of mt-variants with high frequency were identified. However, highly frequent mt-variants occur not only in HCC nodules but also in peri-tumorous parenchymal foci raising the possibility that mtDNA mutations might precede nuclear alterations and play a role in the pre-tumor machinery. Furthermore, the occurrence of identical mt-variants in different nodules of one liver sample indicates the monoclonal HCC origin. Most notably, the increasing numbers of mt-variants as well as the increasing frequency of a particular mt-hot-spot mutation refer to the progression of the HCC dedifferentiation. This accumulation of mt-hot-spot variants in highly dedifferentiated nodules was associated with an enrichment of nuclear mutations as shown in the RPS6KA3, TP53, ARID2, ARID1A or the ATM gene. In conclusion, screening of mitochondrial genome by ultra-deep sequencing is a reliable and useful molecular tool to identify pre-tumorous nodules with high transformation potential and to illustrate tumor clonality and history. Early appearance and high frequency of mt-hot spot mutations associated with HCC development and nuclear genomic alterations provide novel insights in cancer diagnostics and therapeutic approaches.
    Zeitschrift für Gastroenterologie 01/2015; 53(01). DOI:10.1055/s-0034-1397153
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    ABSTRACT: Small cell lung cancer and extrapulmonary small cell carcinomas are the most aggressive type of neuroendocrine carcinomas. Clinical treatment relies on conventional chemotherapy and radiotherapy; relapses are frequent. The PD-1/PD-L1/PD-L2 pathway is a major target of anti-tumour immunotherapy. Aberrant PD-L1 or PD-L2 expression may cause local immune-suppression. Here we investigated expression of PD-1 and its ligands by immunohistochemistry and RNA-seq in small cell carcinomas. PD-L1 and PD-1 protein expression were analysed in 94 clinical cases of small cell carcinomas (61 pulmonary, 33 extrapulmonary) by immunohistochemistry using two different monoclonal antibodies (5H1, E1L3N). RNA expression was profiled by RNA-seq in 43 clinical cases. None of the small cell carcinomas showed PD-L1 protein expression in tumour cells. PD-L1 and PD-1 expression was noticed in the stroma: Using immunohistochemistry, 18.5% of cases (17/92) showed PD-L1 expression in tumour-infiltrating macrophages and 48% showed PD-1 positive lymphocytes (45/94). RNA-seq showed moderate PD-L1 gene expression in 37.2% (16/43). PD-L1 was correlated with macrophage and T-cell markers. The second PD-1 ligand PD-L2 was expressed in 27.9% (12/43) and showed similar correlations. Thus, the PD-1/PD-L1 pathway seems activated in a fraction of small cell carcinomas. The carcinoma cells were negative in all cases, PD-L1 was expressed in tumour-infiltrating macrophages and was correlated with tumour-infiltrating lymphocytes. Patients with stromal PD-L1/PD-L2 expression may respond to anti-PD-1 treatment. Thus, evaluation of the composition of the tumour microenvironment should be included in clinical trials. Besides conventional immunohistochemistry, RNA-seq seems suitable for detection of PD-L1/PD-L2 expression and might prove to be more sensitive. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.
    European journal of cancer (Oxford, England: 1990) 01/2015; 51(3). DOI:10.1016/j.ejca.2014.12.006
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    ABSTRACT: Genomic translocation events frequently underlie cancer development through generation of gene fusions with oncogenic properties. Identification of such fusion transcripts by transcriptome sequencing might help to discover new potential therapeutic targets. We developed TRUP (Tumor-specimen suited RNA-seq Unified Pipeline) (, a computational approach that combines split-read and read-pair analysis with de novo assembly for the identification of chimeric transcripts in cancer specimens. We apply TRUP to RNA-seq data of different tumor types, and find it to be more sensitive than alternative tools in detecting chimeric transcripts, such as secondary rearrangements in EML4-ALK-positive lung tumors, or recurrent inactivating rearrangements affecting RASSF8.
    Genome Biology 01/2015; 16(7). DOI:10.1186/s13059-014-0558-0
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    ABSTRACT: Vimentin is currently used to differentiate between malignant renal carcinomas and benign oncocytomas. Recent reports showing Vimentin positive oncocytomas seriously question the validity of this present diagnostic approach. Vimentin 3 is a spliced variant and ends with a unique C-terminal ending after exon 7 which differentiates it from the full length version that has 9 exons. Therefore, the protein size is different; the full length Vimentin version has a protein size of ~57 kDa and the truncated version of ~47 kDa. We designed an antibody, called Vim3, against the unique C-terminal ending of the Vimentin 3 variant. Using immune histology, immune fluorescence, Western blot, and qRT-PCR analysis, a Vim3 overexpression was detectable exclusively in oncocytoma, making the detection of Vim3 a potential specific marker for benign kidney tumors. This antibody is the first to clearly differentiate benign oncocytoma and the mimicking eosinophilic variants of the RCCs. This differentiation between malignant and benign RCCs is essential for operative planning, follow-up therapy, and patients’ survival. In the future the usage of Vimentin antibodies in routine pathology has to be applied with care. Consideration must be given to Vimentin specific binding epitopes otherwise a misdiagnosis of the patients’ tumor samples may result.
    Disease markers 01/2015; 2015:1-8. DOI:10.1155/2015/368534
  • Journal of Thoracic Oncology 01/2015; DOI:10.1097/JTO.0000000000000503
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    ABSTRACT: Cervical carcinoma develops from preneoplasia by a multistep process. Although most low-grade dysplastic lesions will regress without intervention and even high-grade changes exhibit a substantial rate of regression, a small percentage of dysplasia will progress over time. Thus, indicators are needed to estimate the biological risk and to help avoid overtreatment in women who desire to preserve fertility. In addition to the classical biomarkers, PCR-ELISA-determined HPV genotype and immunohistochemically assessed p16INK4a and Ki-67 expression, cells with integrated HPV and copy number gain of TERC and c-myc were quantified in a panel of 104 benign, intraepithelial neoplastic (CIN I, II, III) and cancerous lesions using fluorescence in situ hybridization. Optimal cut-off values were calculated; Kaplan-Meier curves and a Cox proportional hazard regression model were used to evaluate prognostic signatures. The assay reliably identified HPV integration, TERC and c-myc copy number gain as determined by comparisons with established biomarkers. All biomarker levels increased with the progression of the disease. However, only c-myc copy number gain independently prognosticated a low probability of dysplastic regression. Our results suggest that c-myc plays a key role in the process of dysplastic transformation and might thus be exploited for treatment and follow-up decision-making of cervical dysplasia.
    Oncotarget 12/2014;

Publication Stats

13k Citations
2,172.84 Total Impact Points


  • 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
      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