Torsten Kroll

Universitätsklinikum Jena, Jena, Thuringia, Germany

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Publications (23)65.8 Total impact

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    ABSTRACT: The majority of targeted personalized cancer therapies are effective only in part of the patients, and most of these drugs are excessively expensive. Therefore, methods are urgently required, which reveal already early during treatment, whether the therapy is effective. In the present report, monitoring of circulating epithelial tumor cells (CETC) was used as a timely control of trastuzumab therapy in patients with HER2/neu-positive breast cancer. Seventy-nine sequential HER2/neu-positive breast cancer patients, 35 without trastuzumab, and 36 treated with 1 year of trastuzumab treatment were included. CETC from unseparated white blood cells stained with FITC-anti-EpCAM were analyzed repeatedly during chemotherapy and between 2 and 10 times during 1 year of maintenance treatment or observation. Patients treated with trastuzumab had a better relapse-free survival than patients without trastuzumab treatment during the first 2-4 years of follow-up. Decrease in numbers or no change versus highly variable numbers or increase (fivefold or more) allowed to discriminate highly significantly and clearly (P < 0.0001, hazard ratio 5.5) between patients with a low or high risk of relapse. An increase in CETC was accompanied by an increasing portion of cells containing a very high number of HER2/neu gene amplificates. Analysis of the behavior of CETC can, in the future, contribute to evaluate the efficacy of targeted therapy early during the course of the disease, sparing patients unnecessary treatment but also to reduce the costs for the health system and to downsize the extent and length of clinical studies.
    Journal of Cancer Research and Clinical Oncology 09/2011; 137(9):1317-27. · 2.91 Impact Factor
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    ABSTRACT: In malignant tumors, predictive markers have been developed with respect to targeted therapies. One of the first targeted therapies was the hormone-blocking treatment of tumors of the male and female reproductive system. A typical therapy in breast cancer is the use of the selective estrogen receptor modulator, tamoxifen. However, only some of the patients, positive for the target molecules, respond to the selected therapy. It would, therefore, be highly desirable to have a tool to promptly assess the therapeutic efficacy of the applied agent in the individual patient. Longitudinal observation of CETC provides a unique tool for monitoring therapy response. About 178 patients with breast cancer were followed prospectively during hormone therapy, requiring only 1 ml of peripheral blood, using a fluorochrome-labeled antibody against surface-epithelial antigen. Image analysis allowed CETC numbers to be calculated in relation to blood volume and monitoring over the entire course of treatment. A more than tenfold increase in CETC during therapy was a strong indicator of looming relapse (P = 0.0001 hazard ratio 5.5; 95% confidence interval 1,297-23,626), and a Cox regression analysis of age, tumor size, receptor expression, nodal status and previous treatment resulted in a regression model, in which CETC behavior was the parameter with the highest independent correlation to relapse-free survival. The change in the number of CETC (increase or decrease) may, in the future, be used to guide therapy in order to change to other available treatment options in good time.
    Journal of Cancer Research and Clinical Oncology 05/2011; 137(5):821-8. · 2.91 Impact Factor
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    ChemBioChem 02/2010; 11(5):649-52. · 3.74 Impact Factor
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    ABSTRACT: A new chimerism analysis based on automated interphase fluorescence in situ hybridization (FISH) evaluation was established to detect residual cells after allogene sex-mismatched bone marrow or blood stem-cell transplantation.Cells of 58 patients were characterized as disease-associated due to presence of a bcr/abl-gene-fusion or a trisomy 8 and/or a simultaneous hybridization of gonosome-specific centromeric probes. The automatic slide scanning platform Metafer with its module MetaCyte was used to analyse 3,000 cells per sample. Overall 454 assays of 58 patients were analyzed. 13 of 58 patients showed residual recipient cells at one stage of more than 4% and 12 of 58 showed residual recipient cells less than 4%, respectively. As to be expected, patients of the latter group were associated with a higher survival rate (48 vs. 34 month). In only two of seven patients with disease-marker positive residual cells between 0.1-1.3% a relapse was observed. Besides, disease-marker negative residual cells were found in two patients without relapse at a rate of 2.8% and 3.3%, respectively. The definite origin and meaning of disease-marker negative residual cells is still unclear. Overall, with the presented automatic chimerism analysis of interphase FISH slides, a sensitive method for detection of disease-marker positive residual cells is on hand.
    Molecular Cytogenetics 02/2009; 2:12. · 2.36 Impact Factor
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    ABSTRACT: The interaction of magnetic core shell nanoparticles with living cells depends on the structure of the shell. In this paper we demonstrate a strong difference in the cell–nanoparticle interaction depending on the backbone of carboxymethylated polysaccharides used as shell material. Carboxymethyl cellulose with its β-1→4 linked structure and the carboxymethylated pullulan [α-1→6 linked maltotriose with α-1→4 linkages] show a constant interaction rate with both, tumor cells and leukocytes. In contrast, carboxymethyl dextran with a α-1→6 linked backbone exhibits a rapid interaction kinetic with tumor cells that is reduced with leukocytes as target.
    Journal of Magnetism and Magnetic Materials 01/2009; 321(10):1469-1473. · 1.83 Impact Factor
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    Cell Communication and Signaling 01/2009; 7. · 5.09 Impact Factor
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    Journal of Magnetism and Magnetic Materials 01/2009; 321(10):1469–1473. · 1.83 Impact Factor
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    ABSTRACT: Products derived from roots of Leuzea carthamoides (Maral root) are being promoted as dietary supplements with anti-aging, adaptogenic and anabolic activity, without much scientific evidence. We investigated the effects of a lipophilic Leuzea root extract and the major phytoecdysteroid, 20-hydroxyecdysone, in human breast adenocarcinoma MCF-7 cells. Cell proliferation was inhibited by the extract (IC50 = 30 microg/mL) but not by 20-hydroxyecdysone. Genome-wide expression profiling using Affymetrix HG U133 Plus 2.0 microarrays was carried out to analyse effects at the transcriptional level. 241 genes appeared to be differentially expressed after Leuzea treatment, more than after treatment with either 17beta-estradiol or tamoxifen. Transcripts linked to cell cycle regulation and DNA replication were highly over-represented and regulated in an anti-proliferative manner. Genes involved in apoptosis were regulated in a pro-apoptotic manner. Expression levels of several oxidoreductase transcripts were strongly induced, most prominent CYP1A1, known to be regulated via the aryl hydrocarbon receptor pathway. An XRE-dependent reporter gene assay confirmed the AhR-agonistic activity of the Leuzea root extract, whereas 20-hydroxyecdysone was not active. Leuzea extract also inhibited 5alpha-reductase, type II. While the extract significantly modulates cellular activities, the phytoecdysteroids, are most likely not the active principles of L. carthamoides.
    Planta Medica 12/2008; 74(14):1701-8. · 2.35 Impact Factor
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    Annals of Oncology 10/2008; 19(12):2090-1. · 7.38 Impact Factor
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    ABSTRACT: Bone morphogenetic proteins (BMPs) are multifunctional regulators of various cell functions. The BMP-signalling network plays a pivotal role during embryogenesis and tumorigenesis. BMPs, e.g. BMP-2 exert their biological function in a time and concentration-dependent manner but also modulated by the context of the cellular microenvironment. In this study, we investigated the effect of a steady high level of BMP-2 versus a single application of BMP-2 on the breast cancer cell line MCF-7. The effect of the incubation regimes was analysed by DNA microarray expression profiling. Data were verified by real-time PCR. The protein expression of apoptosis-related genes was studied by western blot analysis. We found a clear difference in the altered gene expression between the constant high level and the single application of BMP-2. After grouping the genes of interest into the biological processes of Gene Ontology, the group of apoptosis-related genes like BAX, BAG5 or PKR, was predominantly affected under the single-application regime of BMP-2. Among these protein kinase R was the most prominently regulated. Further studies on the protein level showed activation of PKR after 4 h with a subsequent enhanced phosphorylation of the PKR substrate eIF2alpha for several hours. The duration of treatment and the concentration of BMP-2 affect the global expression pattern of MCF-7 cells. Among the regulated cancer-related genes, the cohort of the apoptosis-related genes showed the pronounced alterations. Our data point to a novel role of BMP-2 in the regulation of the PKR pathway in tumorigenesis.
    Journal of Cancer Research and Clinical Oncology 05/2008; 134(11):1237-45. · 2.91 Impact Factor
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    ABSTRACT: To demonstrate that it is possible to monitor the response to adjuvant therapy by repeated analysis of circulating epithelial tumor cells (CETCs) and to detect patients early who are at risk of relapse. In 91 nonmetastatic primary breast cancer patients, CETCs were quantified using laser scanning cytometry of anti-epithelial cell adhesion molecule-stained epithelial cells from whole unseparated blood before and during adjuvant chemotherapy. Numbers of CETCs were analyzed before therapy, before each new cycle, and at the end of chemotherapy. The following three typical patterns of response were observed: (1) decrease in cell numbers (> 10-fold); (2) marginal changes in cell numbers (< 10-fold); and (3) an (sometimes saw-toothed) increase or an initial decrease with subsequent reincrease (> 10-fold) in numbers of CETCs. Twenty relapses (22%) were observed within the accrual time of 40 months, including one of 28 patients from response group 1, five of 30 patients from response group 2, and 14 of 33 patients from response group 3. The difference in relapse-free survival was highly significant for CETC (hazard ratio = 4.407; 95% CI, 1.739 to 9.418; P < .001) between patients with decreasing cell numbers and those with marginal changes and between patients with marginal changes and those with an increase of more than 10-fold (linear Cox regression model). These results show that peripherally circulating tumor cells are influenced by systemic chemotherapy and that an increase (even after initial response to therapy) of 10-fold or more at the end of therapy is a strong predictor of relapse and a surrogate marker for the aggressiveness of the tumor cells.
    Journal of Clinical Oncology 04/2008; 26(8):1208-15. · 18.04 Impact Factor
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    ABSTRACT: Treatment efficiency of adjuvant therapy in breast cancer is only revealed after several years by statistical evaluation and gives no answer for the individual patient. We here present a method to analyze the response to adjuvant chemotherapy online in individual patients. In 25 consecutive non-metastatic primary breast cancer patients adjuvant fluorouracil/epirubicin/cyclophosphamid (FEC) or EC followed by taxane (EC-T) or cyclophosphamid/methotrexate/fluorouracil (CMF) therapy were given. Circulating epithelial tumor cells (CETC) were quantified before and after each second cycle of the therapy regimen, between the anthracycline and the taxane block of the regimen and in some cases repeatedly during CMF treatment. Independent of the initial cell number CETC numbers showed a decline, no change or a minor increase in 15 patients of which 14 remained in complete remission and 1 suffered local relapse. Ten patients showed an increase at the end of therapy of which 4 have relapsed during the observation time of between 2 months and up to 54 months. This patient group was compared to a previously published group of 25 patients who have all reached a follow-up of 4.5 years or until relapse. As in the previous report, Kaplan-Meier analysis revealed a high correlation between the response of CETC to therapy and relapse (p < 0.0001) and curves of both patient groups were super imposable. Multivariate analysis revealed the response of CETC to therapy to be an independent predictive marker for relapse.
    Journal of Cancer Research and Clinical Oncology 01/2008; 134(1):59-65. · 2.91 Impact Factor
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    ABSTRACT: Extracts from the rhizome of Cimicifuga racemosa (black cohosh) are increasingly popular as herbal alternative to hormone replacement therapy (HRT) for the alleviation of postmenopausal disorders. However, the molecular mode of action and the active principles are presently not clear. Previously published data have been largely contradictory. We, therefore, investigated the effects of a lipophilic black cohosh rhizome extract and cycloartane-type triterpenoids on the estrogen receptor positive human breast cancer cell line MCF-7. Both extract and purified compounds clearly inhibited cellular proliferation. Gene expression profiling with the extract allowed us to identify 431 regulated genes with high significance. The extract induced expression pattern differed from those of 17beta-estradiol or the estrogen receptor antagonist tamoxifen. We observed a significant enrichment of genes in an anti-proliferative and apoptosis-sensitizing manner, as well as an increase of mRNAs coding for gene products involved in several stress response pathways. These functional groups were highly overrepresented among all regulated genes. Also several transcripts coding for oxidoreductases were induced, as for example the cytochrome P450 family members 1A1 and 1B1. In addition, some transcripts associated with antitumor but also tumor-promoting activity were regulated. Real-Time RT-PCR analysis of 13 selected genes was conducted after treatment with purified compounds - the cycloartane-type triterpene glycoside actein and triterpene aglycons - showing similar expression levels compared to the extract. No estrogenic but antiproliferative and proapoptotic gene expression was shown for black cohosh in MCF-7 cells at the transcriptional level. The effects may be results of the activation of different pathways. The cycloartane glycosides and - for the first time - their aglycons could be identified as an active principle in black cohosh.
    BMC Pharmacology 02/2007; 7:11.
  • Onkologe. 01/2007; 13(1):32-45.
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    ABSTRACT: Tumorzellen zeichnen sich in der Regel durch vernderte intrazellulre Signalwege aus. Knotenpunkte dieses komplexen Kommunikationsnetzwerks bieten sich als Angriffspunkte fr die Krebstherapie an. Mit Hilfe niedermolekularer Substanzen knnen die aktiven Zentren dieser Proteine, die hufig zur Klasse der Kinasen gehren, blockiert werden. Diese zielorientierte Therapie gewinnt zunehmend an Bedeutung und fhrt in Kombination mit etablierten Therapieformen zu Erfolgen.Targeting intracellular pathways is a promising new approach in cancer treatment. During tumorigenesis key elements of the intracellular signalling network are altered in their biological activity. Low-molecular-weight compounds directed against the active motifs of kinases or other regulatory proteins therefore open up new therapeutic options, especially in combination with established cancer therapies.
    Der Onkologe 12/2006; 13(1):32-45. · 0.13 Impact Factor
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    Torsten C Kroll, Stefan Wölfl
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    ABSTRACT: Data from gene expression arrays are influenced by many experimental parameters that lead to variations not simply accessible by standard quantification methods. To compare measurements from gene expression array experiments, quantitative data are commonly normalised using reference genes or global normalisation methods based on mean or median values. These methods are based on the assumption that (i) selected reference genes are expressed at a standard level in all experiments or (ii) that mean or median signal of expression will give a quantitative reference for each individual experiment. We introduce here a new ranking diagram, with which we can show how the different normalisation methods compare, and how they are influenced by variations in measurements (noise) that occur in every experiment. Furthermore, we show that an upper trimmed mean provides a simple and robust method for normalisation of larger sets of experiments by comparative analysis.
    Nucleic Acids Research 07/2002; 30(11):e50. · 8.28 Impact Factor
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    ABSTRACT: Gene expression patterns provide detailed insights into cellular regulation that reflect minor differences of cellular capacity not accessible by standard descriptions of the cellular phenotype or origin. To identify fundamental differences and similarities we analyzed the gene expression patterns of four breast cancer cell lines: MCF-7, SK-BR-3, T-47D, and BT-474. Although only a small subset of genes (597) is represented on the Atlas-cDNA-Array (Clontech) used, clear differences in the expression of a number of genes could be detected. For example, unique high levels of expressions were found for the HLH-protein ID-1 (MCF-7) and the receptor tyrosine kinase erbB2 (SK-BR-3 and T-47D). Most genes analyzed were expressed at comparable levels in all cell lines studied. For interpretation of the results sets of genes that show similar variation of expression among the cells were grouped together. Furthermore, our analysis allows the assignment of similarity values that lead to a relation profile of the cell lines. How these results correlate with known biological properties of the cell lines is discussed. Additionally, we demonstrate that results obtained by cDNA-Array hybridization for expression of the ErbB receptor family correlate well with competitive RT-PCR, thus confirming the reliability of the cDNA-Array analysis.
    Journal of Cancer Research and Clinical Oncology 04/2002; 128(3):125-34. · 2.91 Impact Factor
  • Nature Genetics - NAT GENET. 01/2001; 27(4):96-96.
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    ABSTRACT: Wie hnlich sind Faltungsintermediate dem nativen Protein, und welches ist der geschwindigkeitsbestimmende Schritt bei der Proteinfaltung? Unterstützen neue Ribozyme die RNA-Welt-Hypothese? In der Genomforschung ist die Hlfte der Zeit um - erreichte man auch die Hlfte der angestrebten Ziele? Und welche Datenbank informiert den Suchenden über den Stand der Genomforschung? Die diesjhrigen Trendberichte gehen diesen Fragen nach.
    Nachrichten aus der Chemie 01/1999; 47(2):175 - 185. · 0.20 Impact Factor