Characterization of covalently modified deoxyribonucleosides formed from dibenz[a,j]anthracene in primary cultures of mouse keratinocytes

Abstract

Identification of various deoxyribonucleoside adducts formed in primary cultures of mouse keratinocytes exposed to dibenz[a,j]anthracene (DB[a,j]A) is presented. A preliminary analysis of the DNA adducts formed from 7-methyldibenz[a,j]anthracene (7MeDB[a,j]A) also is presented. Cultures of keratinocytes obtained from dorsal skins of female SENCAR mice were exposed to 0.5 microgram of tritium-labeled hydrocarbons/mL of medium for 24 h. The total DNA binding was 2.23 +/- 0.54 and 5.28 +/- 0.97 pmol of hydrocarbon/mg of DNA for DB[a,j]A and 7MeDB[a,j]A, respectively. These binding values represented the radioactivity associated with the modified deoxyribonucleosides separated from the normal deoxyribonucleosides on Sephadex LH-20 columns following enzymatic digestion of isolated DNA. Treatment of keratinocytes with DB[a,j]A produced adduct peaks corresponding to marker adducts derived from trans addition of both deoxyguanosine as well as deoxyadenosine residues to the (+) enantiomer of the anti-diol epoxide where the deoxyadenosine adducts were predominant. In addition, DNA adduct peaks corresponding to markers of trans and cis addition, respectively, of deoxyguanosine and deoxyadenosine to the (+)-syn-diol epoxide were also noted in these chromatograms. A major DNA adduct in cells exposed to DB[a,j]A was tentatively identified as resulting from the addition of deoxyadenosine to DB[a,j]A-5,6-oxide. Several other later eluting DNA adduct peaks, not corresponding to any of the marker adducts, were also present in these chromatograms. In comparison, when cells were exposed to the more biologically potent 7-methyl analogue, at least 12 DNA adduct peaks were consistently observed in HPLC chromatograms.(ABSTRACT TRUNCATED AT 250 WORDS)

Integrating Field Analyses with Laboratory Exposures to Assess Ecosystems Health

“…Topical application of dibenz [a,j]anthracene and its metabolites to mouse skin gave at least 23 DNA adducts, including four less polar (derived from synand anti-dibenz [a,j]anthracene -3,4-diol-1,2-oxide; 23% of total adducts) and 19 highly polar (derived primarily from the dibenz [a,j]anthracene-3,4:10,11-bis-diol; 77% of total adducts) DNA adducts (Vulimiri et al, 1999). Dibenz [a,j]anthracene forms DNA adducts in primary cultures of mouse keratinocytes that were identified as (+)-anti-dibenz [a,j]anthracene-3,4-diol-1,2-oxide-deoxyguanosine adducts, (+)-anti-dibenz [a,j]anthracene-3,4-diol-1,2-oxide-deoxyadenosine adducts (the deoxyadenosine adducts were predominant), trans and cis adducts with deoxyguanosine and deoxyadenosine of (+)-syndibenz [a,j]anthracene-3,4-diol-1,2-oxide and the major adduct, dibenz [a,j]anthracene-5,6-oxide-deoxyadenosine (Nair et al, 1991).…”

“…Racemic anti-dibenz [a,j]anthracene-3,4-diol-1,2-oxide formed DNA adducts with calf thymus DNA. The major adducts were (+)-anti-trans-dibenz [a,j]anthracene-3,4-diol-1,2-oxide-deoxyguanosine and (+)-antitrans-dibenz [a,j]anthracene -3,4-diol-1,2-oxide-deoxyadenosine (major adduct) (Nair et al, 1989(Nair et al, , 1991.…”

Benzo[ghi]perylene Induces Morphological and Genotoxic Effects in Human Bronchial Cells Independently of The AhR Pathway

“…The results of exposure to B property, such that no adducts are produced. This K region, which is present in other PAH as wellincluding B[ghi]p -preferentially generates deoxyguanosine (Rojas and Alexandrov 1986) and deoxyadenosine (Nair et al 1991). In this regard, Desler et al (2009) propose that the PAH with no bay or gulf regions are generators of oxidative stress, and that it is through this pathway that they cause oxidative damage in nitrogenous bases of DNA such as 8-oxo-dG.…”

Targeted A → T and G → T Mutations Induced by Site-Specific Deoxyadenosine and Deoxyguanosine Adducts, Respectively, from the (+)-anti-Diol Epoxide of Dibenz[a,j]anthracene in M13mp7L2

“…DB[a,j]A (Figure 1), a nonalternant PAH, is an effective tumor initiator in mouse skin although less potent than B[a]P (DiGiovanni et al, 1983;Sawyer et al, 1988). This compound, like other PAHs, appears to generate its carcinogenic action through metabolic conversion of the parent hydrocarbon into diol epoxide derivatives (Baer-Dubowska et al, 1995;Nair et al, 1991;Sawyer et al, 1988). In particular, the (+)-anti-diol epoxide (Figure 1) is a more potent tumor initiator than the parent compound Sawyer et al, 1988).…”

“…The major reaction products obtained with either racemic or pure (+)anti-DB[a,j]A-diol epoxide [(+)anti-DB[a,j]A-DE] arise through trans addition of the exocyclic amino groups of dGuo and dAdo (Figure 1). Treatment of cultured mouse keratinocytes with DB[a,j]A produced adducts with both dGuo and dAdo residues covalently bound to the (+)enantiomer of the anti-diol epoxide where the dAdo adducts were predominant (Nair et al, 1991). The (+)anti-DB[a,j]A-DE-trans-N 6 -dAdo adduct was also found in mouse epidermal DNA after topical application of DB[a,j]A (Baer-Dubowska et al, 1995).…”