Cytogenetic effects of promutagens in genetically engineerd V79 Chinese hamster cells expressing cytochromes P450.

V79 Chinese hamster cell lines genetically engineered to express rat CYP2B1, CYP1A1, CYP1A2, and their parental cell lines V79-MZ, without acetyltransferase, and V79-NH, with acetyltransferase, were studied for chromosome aberrations and sister chromatid exchange induced by aflatoxin B1, cyclophosphamide, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine. The parental V79 cell lines did not show clastogenic effects. Significant clastogenic effects were observed after an 18 h exposure to aflatoxin B1 and cyclophosphamide in CYP2B1 expressing cells, to benzo[a]pyrene in CYP1A1 and CYP1A2 expressing cells, to 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine in cells, expressing CYP1A2 with or without acetyltransferase, and to cyclophosphamide in cells expressing both CYP1A2 and acetyltransferase. A significant sister chromatid exchange inducing effect was found after a 24 h exposure in each of the genetically engineered cell lines, except for benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene in CYP2B1 expressing cells, and for benzo[a]pyrene in cells expressing both CYP1A2 and acetyltransferase. Thus, a battery of cell lines genetically engineered for metabolic competence may serve as a tool for investigating chromosomal changes induced by activated xenobiotics

Development and validation of a fluorescence HPLC-based screening assay for inhibition of human estrogen sulfotransferase

Human estrogen sulfotransferase (SULT1E1) is involved in the regulation of 17β-estradiol responsiveness and is believed to protect peripheral tissues from excessive estrogenic effects. Several assays already have been developed to investigate the inhibitory effect of endocrine-disrupting compounds (EDCs) on SULT1E1. However, most of these assays make use of the radiolabeled cofactor

Die Nutzung hepatischer Funktionen fuer In-vitro-Verfahren zur Pruefung von Stoffen mit dem Ziel der Einsparung von Versuchstieren. T. 8: Gentechnische Konstruktion und Nutzung von Zellinien, die hepatische Sulfotransferasen des Menschen und von Versuchstieren stabil exprimieren Schlussbericht

cDNAs encoding rat and human xenobiotic-metabolizing sulfotransferases were cloned and stably expressed in Chinese hamster V79 cells, alone or in combination with a cDNA of a cytochrome P450. The heterologously expressed enzymes showed the same electrophoretic properties and immunoreactivities as the naturally expressed enzymes from rat and human tissues. Enzyme activities towards various substrates were determined in intact cells as well as their subscellular preparations using radiometric and mass spectrometric methods. Activities were compared between cells grown under different culture conditions (passages after establishment of the recombinant cell line, presence of selecting agents, cell density, serum batch). Reference values for enzyme activities were established. Furthermore, the cells were used for the detection of sulfotransferase-mediated cyototoxic effects and genotoxic effects (gene mutations, sister chromatid exchange, DNA adducts) of chemicals. The systems were established and optimized using various pro-genotoxicants, such as 2-acetylaminofluorene and its N-hydroxylated derivative, #alpha#-hydroxytamoxifen, primary and secondary benzylic alcohols, and 2-nitropropane. (orig.)Available from TIB Hannover: F99B43 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman