title: Benzo[a]pyrene- and formaldehyde-induced DNA damage and repair in rat tracheal epithelial cells.
abstract: The single and combined effects of 2 environmental carcinogens, benzo[a]pyrene (BAP) and formaldehyde (HCHO), on cell growth and DNA damage were assessed in a rat tracheal epithelial cell line, C18. Treatment of C18 cells with HCHO for 90 min reduced the calculated growth index at the highest concentration tested, 400 microM, while no growth effects were observed with BAP treatments. Combination treatments reduced the growth index to 75% of control values. Alkaline elution analysis of C18 cell DNA detected both DNA-protein crosslinks (DPC) and single-strand breaks (SSB) as a result of HCHO treatment, while BAP caused only SSB. HCHO-induced SSB were repaired within 2 h, whereas BAP-induced SSB persisted for at least 48 h. Combination treatment of cells with BAP followed by HCHO enhanced the number of SSB, but reduced DPC. The results are discussed in reference to earlier work which demonstrated the interaction in vivo between BAP and HCHO with respect to their carcinogenicity in rat tracheal implants.
authors.affiliation: Oak Ridge Graduate School of Biomedical Sciences, University of Tennessee, Oak Ridge National Laboratory 37831.
authors.forename: G N
authors.initials: GN
authors.lastname: Cosma
authors.forename: A C
authors.initials: AC
authors.lastname: Marchok
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D015197:Carcinogenicity Tests / Q000379:methods; D002273:Carcinogens; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003043:Cocarcinogenesis; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000187:drug effects; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D005557:Formaldehyde / Q000633:toxicity*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D014132:Trachea / Q000166:cytology / Q000187:drug effects
chemical_list: D002273:Carcinogens; D004277:DNA, Single-Stranded; D005557:Formaldehyde; D001564:Benzo(a)pyrene; D004247:DNA