title: Specific BPDE I modification of replicating and parental DNA from early S phase human foreskin fibroblasts.
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.
authors.forename: M L
authors.initials: ML
authors.lastname: Ribovich
authors.forename: P
authors.initials: P
authors.lastname: Kurian
authors.forename: G E
authors.initials: GE
authors.lastname: Milo
mesh_terms: D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D001580:Benzopyrenes / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis / Q000378:metabolism*; D018736:DNA Adducts; D004261:DNA Replication / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D007399:Interphase; D008297:Male; D008745:Methylation; D009711:Nucleotides / Q000378:metabolism
chemical_list: D001580:Benzopyrenes; D002273:Carcinogens; D018736:DNA Adducts; D009711:Nucleotides; C043931:benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-DNA; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D004247:DNA