Characterization of environmental chemicals with potential for DNA damage using isogenic DNA repair-deficient chicken DT40 cell lines

Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Japan.
Environmental and Molecular Mutagenesis (Impact Factor: 2.63). 08/2011; 52(7):547-61. DOI: 10.1002/em.20656
Source: PubMed

ABSTRACT Included among the quantitative high throughput screens (qHTS) conducted in support of the US Tox21 program are those being evaluated for the detection of genotoxic compounds. One such screen is based on the induction of increased cytotoxicity in seven isogenic chicken DT40 cell lines deficient in DNA repair pathways compared to the parental DNA repair-proficient cell line. To characterize the utility of this approach for detecting genotoxic compounds and identifying the type(s) of DNA damage induced, we evaluated nine of 42 compounds identified as positive for differential cytotoxicity in qHTS (actinomycin D, adriamycin, alachlor, benzotrichloride, diglycidyl resorcinol ether, lovastatin, melphalan, trans-1,4-dichloro-2-butene, tris(2,3-epoxypropyl)isocyanurate) and one non-cytotoxic genotoxic compound (2-aminothiamine) for (1) clastogenicity in mutant and wild-type cells; (2) the comparative induction of γH2AX positive foci by melphalan; (3) the extent to which a 72-hr exposure duration increased assay sensitivity or specificity; (4) the use of 10 additional DT40 DNA repair-deficient cell lines to better analyze the type(s) of DNA damage induced; and (5) the involvement of reactive oxygen species in the induction of DNA damage. All compounds but lovastatin and 2-aminothiamine were more clastogenic in at least one DNA repair-deficient cell line than the wild-type cells. The differential responses across the various DNA repair-deficient cell lines provided information on the type(s) of DNA damage induced. The results demonstrate the utility of this DT40 screen for detecting genotoxic compounds, for characterizing the nature of the DNA damage, and potentially for analyzing mechanisms of mutagenesis.

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Available from: Raymond R Tice, Sep 28, 2015
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    • "Thus, DT40 are advantageous in the functional and mechanistic screening of various toxicants. Currently, they are used primarily in the study of genotoxicants, as the majority of the cell lines harbor various individual deletions in DNA repair genes (Ridpath et al., 2007; Yamamoto et al., 2011; Lee et al., 2013). Although other cellular components and processes are not represented in the set of mutants, the cells could become another general resource if additional deletions are generated. "
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    • "According to the International System for Human Cytogenetic Nomenclature (ISCN), chromosomal breakage, i.e. the discontinuity of sister chromatids, is classified into two types: chromatid-type breaks, which involve discontinuity in one of the sister chromatids, and isochromatid-type breaks, which involve discontinuity in both sister chromatids at the same location [4] (Figure S1). Chromosomal breaks are induced by a variety of mutagenic agents, such as ionizing radiation [5]–[8]. It is generally believed that virtually all chromosomal breaks are associated with DSBs at the site of the break. "
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