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Mutational Spectrum of N-Nitrosodimethylamine in vitro and in vivo at Endogenous Mammalian Marker Loci
EPA Grant Number: GF9500964Title: Mutational Spectrum of N-Nitrosodimethylamine in vitro and in vivo at Endogenous Mammalian Marker Loci
Investigators: Dobo, Krista
Institution: University of California - Davis
EPA Project Officer: Broadway, Virginia
Project Period: September 1, 1995 through January 1, 2000
Project Amount: $35,807
RFA: STAR Graduate Fellowships (1995)
Research Category: Fellowship - Health , Academic Fellowships , Health Effects
Description:
Objective:The purpose of this project is to establish a mutational spectrum for Nitrosodimethylamine (NDMA) in order to provide evidence that environmental tobacco smoke (ETS) exposure among nonsmokers is involved in the induction of lung cancer, and other tobacco smoke-related cancers. Of the 43 known carcinogenic components present in ETS, NDMA is one of the most abundant constituents and is also a potent mutagen and carcinogen in numerous animal species. The establishment of the mutational spectrum for NDMA in endogenous mammalian genes is necessary if exposure to NDMA, based on its mutational specificity, is going to be assessed in human tissues. Initially, two human B lymphoblastoid cell lines AHH-1 and MCL-5 will be used to study the mutational spectrum of NDMA. In addition to having metabolic capabilities, AHH-1 and MCL-5 contain two marker loci, hypoxanthine phosphoribosyltransferase (hprt) and thymidine kinase (tk) which can be used for studying mutagenicity. Both loci will be used to study the mutational spectrum of NDMA. The applicability of in vitro systems for the determination of mutational spectra for a given agent can be validated by comparison to spectra observed using in vivo systems. The methodology which will be used to perform this part of the research will include well-established cell culture protocols for the isolation of NDMA-induced tk and hprt mutants. Following isolation of NDMA-induced mutants, genomic DNA will be isolated from each for molecular analysis. In addition to establishing a mutational spectrum for NDMA using human cell lines, in vivo studies will be conducted in mice to determine the mutational spectrum of NDMA at hprt locus. HPRT mutants will be isolated from the spleen of treated mice. Although there are large differences between animal models and cell culture systems, hprt will be the target for mutagenesis in both systems being employed. This will simplify the comparison of the mutational spectra observed in vitro and in vivo. Observation of similar mutational spectra for NDMA in human lymphoblastoid cells treated in vitro and in mouse lymphocytes following in vivo exposure will support the application of in vitro results for comparison to humans. This would allow the establishment of a much larger collection of representative mutants for NDMA in a time and cost-effective manner.
Supplemental Keywords:Scientific Discipline, Health, RFA, Biology, Health Risk Assessment, Immunology, Biochemistry, Environmental Chemistry, cancer risk, Limnology, lung cancer, thymidine kinase (tk), carcinogens, mutational spectrum of Nitrosodimethylamine, mutational spectrum of NDMA in vivo, cancer causation, Nitrosodimethylamine (NDMA), MCL-5, environmental tobacco smoke (ETS), mutational spectrum of NDMA in vitro, endogenous mammalian marker loci, AHH-1