Pretreatment of primary rat cutaneous epidermal keratinocyte culture with a low concentration of MNNG: Effect on DNA cross-linking measured in situ after challenge with bis-2-chloroethyl sulfide

Journal Article · Sun Jan 01 04:00:00 EST 1989 · Journal of Toxicology and Environmental Health; (USA)

DOI:https://doi.org/10.1080/15287398909531307· OSTI ID:5015446

Sorsher, D H; Conolly, R B ^[1]

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1. Univ. of Michigan School of Public Health, Ann Arbor (USA)

Bis-2-chloroethyl sulfide- (BCES-) induced DNA cross-links in confluent, primary cultures of newborn rat cutaneous epidermal keratinocytes were detected using an assay that includes in situ unwinding of the DNA followed by separation of single-stranded DNA and double-stranded DNA (DSDNA) with hydroxylapatite. DNA cross-links in BCES-challenged cultures were inferred form increases in the percentage of DNA the remained double-stranded, compared with control cultures, after a 60-min alkaline unwinding incubation. The amount of DNA cross-linking after 5 or 10 {mu}M BCES was increased when keratinocytes were first pretreated with 0.05 {mu}M MNNG for 1 h at 8 a.m., 2 p.m., and 8 p.m. for two consecutive days and challenged with BCES the following morning. This increase was statistically significant. For example, after 5{mu}M BCES challenge, cultures not pretreated with MNNG had 114.14% control DSDNA, whereas MNNG pretreated cultures had 122.78% control DSDNA. The level of BCES-induced cross-linking was maximal immediately after 30-min challenge and decreased during postchallenge incubation. At 24 and 48 h post 5, 10, or 20 {mu}M BCES challenge, the level of DSDNA was actually depressed below unchallenged levels. This postchallenge decreased in the level of DSDNA, indicative of SSB in DNA, suggests repair activity by glycosylases and endonucleases. However completion of repair (i.e., a return to control levels of DSDNA) was not seen in these experiments. The activity that resulted in decreases in the level of DSDNA during postchallenge incubation response was unaffected by MNNG pretreatment.

• OSTI ID: 5015446
• Journal Information: Journal of Toxicology and Environmental Health; (USA), Journal Name: Journal of Toxicology and Environmental Health; (USA) Vol. 27:3; ISSN JTEHD; ISSN 0098-4108
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKYLATING AGENTS
ANIMAL CELLS
ANIMAL TISSUES
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY
CHEMICAL REACTIONS
CROSS-LINKING
DNA
DNA REPAIR
EPIDERMIS
EPITHELIUM
NITROSO COMPOUNDS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
POLYMERIZATION
RECOVERY
REPAIR
SKIN
TISSUES
TOXICITY