Specific BPDE I modification of replicating and parental DNA from early S phase human foreskin fibroblasts

Carcinogenesis. 1986 May;7(5):737-44. doi: 10.1093/carcin/7.5.737.

Abstract

Replicating DNA was modified by BPDE I to a greater extent than parental DNA when human fibroblast cells were treated with the carcinogen for 30 min in early S phase. Synchronized cells were exposed to 5-bromodeoxyuridine and treated with non-radioactive BPDE I and [methyl-3H]thymidine in early S phase. The density- and tritium-labeled, replicated DNA was separated from parental DNA in a CsCl gradient. The individual carcinogen-DNA adduct levels in both samples were quantitated by using the 32P-postlabeling method. The total modification of replicated DNA was 1.4-2.4 times greater than parental DNA. This difference was mainly reflected by differences in the main adducts, identified as the 3', [5'-32P]bisphosphates of 7R and 7S-BPDE I-dG. Confirmation of the identity of these two specific carcinogen-DNA adducts was accomplished by co-chromatography on t.l.c. with 3H-labeled 3',5'-bisphosphate adducts. The two 3H- and 32P-labeled adducts were isolated and dephosphorylated. The resultant 3H-labeled deoxyribonucleoside adducts were analyzed on h.p.l.c. and identified by co-chromatography with authentic standards. These results suggest that preferential modification of replicating DNA occurs when human cells are treated with BPDE I in early S phase. The ultimate result of this specific modification is the expression of a transformed phenotype.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
  • Benzopyrenes / analysis
  • Benzopyrenes / metabolism
  • Benzopyrenes / toxicity*
  • Carcinogens*
  • Cell Transformation, Neoplastic / drug effects
  • Cells, Cultured
  • DNA / analysis
  • DNA / metabolism*
  • DNA Adducts*
  • DNA Replication / drug effects*
  • Fibroblasts / drug effects
  • Humans
  • Interphase
  • Male
  • Methylation
  • Nucleotides / metabolism

Substances

  • Benzopyrenes
  • Carcinogens
  • DNA Adducts
  • Nucleotides
  • benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-DNA
  • 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
  • DNA