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

Replicating DNA was modified by BPDEI 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 pha...

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Bibliographic Details
Published in:Carcinogenesis (New York) 1986-05, Vol.7 (5), p.737-744
Main Authors: Ribovich, Martin L., Kurian, Ponnamma, Milo, George E.
Format: Article
Language:English
Subjects:
7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
Benzopyrenes - analysis
Benzopyrenes - metabolism
Benzopyrenes - toxicity
Biological and medical sciences
Carcinogenesis, carcinogens and anticarcinogens
Carcinogens
Cell Transformation, Neoplastic - drug effects
Cells, Cultured
Chemical agents
DNA - analysis
DNA - metabolism
DNA Adducts
DNA Replication - drug effects
Fibroblasts - drug effects
Humans
Interphase
Male
Medical sciences
Methylation
Nucleotides - metabolism
Tumors
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Summary:Replicating DNA was modified by BPDEI 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 deoxyribonudeoside 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.
ISSN:0143-3334
1460-2180
DOI:10.1093/carcin/7.5.737