Research Group
Molecular Toxicology [MolTox]

Occupationally dependent exposure to chemicals results in alterations at the molecular level in the organism. It is the aim of the research group to recognize and to analyze these alterations and to find relations to pathogenetic processes such as carcinogenesis. In parallel, we try to identify relevant exposure and effect biomarkers as well as genes which are responsible for the individually different susceptibility for chemically induced adverse effects. In this respect, chemically induced bladder carcinogenesis is a focus of our research. Both the hazardous potential of chemicals as well as the individual-related risk will be considered, analyzed and assessed.

Scientific Members

• Herrmann Bolt
• Kathrin Herbst
• Jeanette Niestroy
• Angufor Numfor
• Peter Roos (head)
• Alfonso Barbara (guest scientist)

Current research

• Field of research 1 "Urothelium, urinary bladder and cancerogenesis of the urinary bladder"
  (Alfonso Barbara, Brigitte Begher-Tibbe, Ingeborg Bichbäumer, Kathrin Herbst, Angufor Numfor, Peter Roos)
  About 80 % of the research group’s capacities are utilized by research on urothelium and bladder carcinogenesis. The activities are closely connected to the parallel development of methods for the analysis of bladder tumor markers and for the study of molecular alterations in urothelial cells following carcinogen treatment.
  Until recently, the bladder epithelium was thought to be non-competent with respect to xenobiotic phase I metabolism. Xenobiotic dependent adverse effects such as bladder carcinogenesis were ascribed to the phase I activities of the liver which efficiently metabolizes xenobiotics by means of cytochromes P450. Resultant reactive metabolites with cell and DNA-damaging potential may reach the bladder epithelium and exert their effects. Own investigations and data from the literature show that urothelial cells express several cytochromes P450 and are therefore capable to generate reactive metabolites by their own. Starting from here, we study several aspects of chemically induced bladder carcinogenesis.
  
  Besides molecular characterization of urothelial cells concerning expression profiles we also study effects of chemicals, in particular of carcinogens, on urothelial cells. For these studies, several human urothelial cell lines as well as exfoliated urothelial cells are used which are excreted with urine. Our work includes the following aspects:
• expression and inducibility of cytochrome P450-enzymes in urothelial cell lines and in exfoliated urothelial cells
• primary effects of carcinogens on the expression of cytochromes P450 in urothelial cells
• mechansims of synergistic effects elicited by carcinogens on the cytochroem P450 system and the Ah-receptor pathway in urothelial cells
• fast effects (within minutes) of carcinogens on components of cell cycle control and signal transduction pathways
• polymorphisms with relevance for bladder carcinogenesis
   
• Field of research 2 "Combination effects of carcinogens and plant flavonoids on cytochrome P450 induction and on the Ah-receptor pathway in duodenal cells"
  (Jeanette Niestroy, Peter Roos)
  The activation of receptors by endogenous and exogenous ligands such as carcinogens is the initial step for reaction cascades resulting in altered transcription rates and finally in altered protein activities. The protein components of signal pathways offer multiple sites for xenobiotic attacks. The Ah-receptor (aryl hydrocarbon receptor) is a key component in the regulation of xenobiotic/carcinogen metabolism. Its function and cellular localization is contolled by interaction with several proteins (ARA9, ARNT, hsp90, p23) and is linked to the transcriptional control of the cytochrome P450 enzymes CYP1A1 und CYP1B1 which metabolize carcinogens such as polycyclic aromatic hydrocarbons (PAH). We study modulatory effects of plant flavonoids on the benzo[a]pyrene activated Ah-receptor pathway in duodenal cells to get insight into the interplay of agonists and anagonists of the pathway.
   
• Field of research 3 "Quantification of proteins and their modifications by mass spectrometric methods using element labels" – Co-operation with Institute of Analytical Scíences (ISAS)
  (Ingeborg Bichbäumer, Angufor Numfor, Peter Roos)
  (ISAS: Ingo Feldmann, Larissa Wäntig, Norbert Jakubowski)
  Sensitive cellular processes such as cell division and differentiation are controlled by complex signaling networks which include numerous proteins. The activities of theses proteins are meticulously regulated to avoid fatal errors in the process flow. Besides by transcriptional control, final protein activities are essentially modulated by post-translational modifications such as phosphorylation and acetylation as well as covalent attachment of small proteins such ubiquitin and SUMO. Thus, protein levels and protein modifications define the final activity status of proteins. Therefore, it is our aim to concomitantly quantify preoteins including their modifications (functional proteome). The development and evaluation of methods is connected to questions of bladder cancer biomarkers and bladder carcinogenesis.
   
• Field of research 4 "Single cell analysis of toxic and carcinogenic effects“ – Co-operation with the Institute of Analytical Scíences (ISAS)
  (Ingeborg Bichbäumer, Peter Roos, NN)
  (ISAS: Ingo Feldmann, Joachim Franzke, Larissa Wäntig, Norbert Jakubowski)
  Usually, molecular effects of xenobiotics and carcinogens on cells are determined in cell or tissue-homogenates. Thus, effects are integrated over the whole cell population. However, it is important to know whether several alterations are effectively realized within one and the same cell as the functional biological entity. Therefore, we analyze carcinogen-dependent and carcinogenesis-related effects in single cells and apply several analytical methods including microfluidic devices. In a new approach we will additionally utilize FACS (fluorescence assisted cell sorter) and ICP-MS (inductively coupled plasma mass spectrometry) based methods.
   
• Intergroup research initiative "Urothelium and chemical toxicity" (UroTox)
  (Meinolf Blaszkewicz, Gisela Degen, Wolfram Föllmann, Klaus Golka, Jan Hengstler, Peter Roos)
  The Intergroup research initiative "UroTox" links experimental research concerning effects of xenobiotics on urinary and bladder (research group "Chemical risks"; research group "Molecular toxicology") with studies in occupational medicine concerning risk factors for tumors of the urinary tract (research group "Systems toxicology"; central support unit "Clinical Occupational Medicine") and tasks of the central support unit "Analytical Chemistry".

Research facilities

• microarray-scanner and hybridization device
• lightcycler for real-time PCR and conventional thermocyclers
• fluorescence assisted cell sorter (FACS), BD Influx
• HPLC
• FPLC and low pressure liquid chromatography
• electrophoresis- and blotting apparatus
• UV/VIS- and fluorescence spectrofotometer
• phosphoimager
• cell culture lab
• light and fluorescence microscopes

Recent grants

• thesis project "Interaction of flavonoids and AhR signaling: effect on absorption, transport and metabolism of xenobiotics". Graduiate college 1427 'Food constituents as triggers of nuclear receptor-mediated intestinal signaling' at the University Düsseldorf; DFG, 2007-2009
• German-Indian Co-operation "Pesticide-induced alterations of expression profiles in brain and in blood lymphoctes as biomarkers of exposure and effect". Bundesministerium für Bildung und Forschung (BMBF), 2008-2010
• Fluorescence asisted cell sorter (FACS), BD Influx Cell Sorter. Ministerium für Innovation, Wissenschaft, Forschung und Technologie des Landes Nordrhein-Westfalen, 2009

Co-operations

• A close and intensive co-operation exists with the Institute for Analytical Sciences (ISAS), Dortmund, concerning the development of new methods for the detection of bladder cancer markers and molecular alterations in urothelial cells. In co-operation with the research group of Dr. Jakubowski, we develop new mass spectrometric methods for the quantitative analysis of proteins and their post-translational modifications. For multiparameter analysis of molecular alterations in single cells, we use microfluidic devices (Dr. Franzke, ISAS).
• Effects of selected chemicals on the cytochrome P450 system and cell cycle control mechanisms in different cell types are studied in a co-operation with the Institute for Environmental Medicine and Hospital Hygiene, Universitätsklinikum Freiburg (Prof. Dr. Mersch-Sundermann).
• Interactions of neurotoxins with the cytochrome P450 system are investigated in a co-operation with the Institute for Organic Chemistry, Universität Würzburg (Prof. Dr. Bringmann).
• Additionally, we co-operate with the Institute for Pathology, Universitätsklinikum Essen (PD Dr. Theegarten) with respect to immunohistochemical investigations of bladder and kidney tissue sections as well as with the Institute for Toxicology, Heinrich-Heine-Universität Düsseldorf within a DFG-funded graduate college (Prof. Dr. Kahl, Prof. Dr. Abel).
• An international co-operation exists with the Industrial Toxicology Research Centre, Lucknow, Indien (Dr. Parmar) concerning biomarkers of exposure and effect for pesticides.

Selected publications

• Roos PH, Golka K, Hengstler JG (2008). Predictive biomarkers and signatures in urinary bladder cancer. Curr Opin Mol Ther 10, 243-250.
• Roos PH, Venkatachalam A, Manz A, Wäntig L, Koehler CU, Jakubowski N (2008). Detection of electrophoretically separated cytochromes P450 by element labelled monoclonal antibodies via laser ablation inductively coupled plasma mass spectrometry. Anal Bioanal Chem 392, 1135–1147.
• Köhler CU, Roos PH (2008). Focus on the Intermediate State: Immature mRNA of Cytochromes P450 - Methods and Insights. Anal Bioanal Chem 392, 1109-1122.
• Jakubowski N, Messerschmidt J, Garijo Anorbe M, Wäntig L, Hayen H, Roos PH (2008). Labelling of proteins by use of iodination and detection by ICP-MS. J Anal At Spectrom 23, 1487-1496.
• Dörrenhaus A, Müller T, Roos PH (2007). Increased CYP1A1 expression in human exfoliated urothelial cells of cigarette smokers compared to non-smokers. Arch Toxicol 81, 19-25.
• Roos PH, Belik R, Föllmann W, Degen GH, Knopf HJ, Bolt HM, Golka K (2006). Expression of cytochrome P450 enzymes CYP1A1, CYP1B1, CYP2E1, and CYP4B1 in non-invasively obtained transitional cells of the human urinary tract. Arch Toxicol 80, 45–52.
• Roos PH, Bolt HM (2005). Cytochrome P450 interactions in human cancers: new aspects considering CYP1B1. Expert Opinion Drug Metab Toxicol 1, 187–202.
• Roos PH, Tschirbs S, Hack A, Welge P, Wilhelm M (2004). Different mechanisms of mammalian species to handle ingested polycyclic aromatic hydrocarbons: Organ-specific response patterns of CYP1A1-induction upon oral intake of PAH-contaminated soils in mipigs and rats. Xenobiotica 34, 781–795.
• Lemm F, Wilhelm M, Roos PH (2004). Occupational exposure to polycyclic aromatic hydrocarbons suppresses constitutive expression of CYP1B1 on the transcript level in human leukocytes. Int J Hyg Environ Health 207, 325–335.

• Publications