Abstract
The environmental pollutants 1,6‐dinitropyrene (1,6‐DNP) and 1,8‐dinitropyrene (1,8‐DNP) are strongly carcinogenic in a number of animal models. These DNPs are metabolized by nitroreduction to N‐hydroxy arylamine derivatives that either directly or after acetylation bind to cellular DNA. In the experiments reported here, we examined whether DNA adduct formation by 1,6‐DNP and 1,8‐DNP was associated with amplification of specific DNA sequences, a process that may be causally related to tumorigenesis. CO60 cells, an SV40‐transformed Chinese hamster embryo cell line, were incubated with 2.5 or 50 ng/mL [4,5,9,10‐^3^H]1,6‐DNP for 5 h. Highpressure liquid chromatographic analysis of organic extracts of the medium indicated the presence of 1‐acetylamino‐6‐nitropyrene, suggesting that these cells are capable of nitroreduction and acetylation. ^32^P‐Postlabeling analysis of DNA isolated from cells exposed to 1.0 or 2.5 ng/mL 1,6‐DNP revealed dose‐related formation of N‐(deoxyguanosin‐8‐yl)‐1‐amino‐6‐nitropyrene. A similar adduct, presumably N‐(deoxyguanosin‐8‐yl)‐1‐amino‐8‐nitropyrene, was detected after incubations with 1,8‐DNP. DNA isolated from analogous experiments was slot‐blotted onto nylon membranes and hybridized with ^32^P‐labeled SV40, c‐fos, or β‐actin DNA probes. β‐Actin was not amplified and c‐fos was amplified only a small amount; however, there was dose‐related amplification of SV40 sequences, whose levels were in some instances approximately 20 times that observed in solvent‐treated controls. These data indicate that DNA adduct formation by 1,6‐DNP and 1,8‐DNP is associated with the amplification of certain DNA sequences, a response that may be related to the tumorigenic potential of these compounds.