Detection of the major DNA adducts of benzo[b]fluoranthene in mouse skin: role of phenolic dihydrodiols.
The primary mechanism of activation of benzo[b]fluoranthene (B[b]F) to a genotoxic agent does not involve the bay region dihydrodiol epoxide trans-9,10-dihydroxy-anti- 11,12-epoxy-9,10,11,12-tetrahydrobenzo[b]fluoranthene (B[b]F-9,10-DE). Previous results have suggested that the major DNA adduct(s) formed in vivo with B[b]F are more polar than those formed from B[b]F-9,10-DE. Employing newly-developed synthetic methods for the formation of B[b]F derivatives, trans-9,10-dihydro-5,9,10-trihydroxybenzo[b]fluoranthene (5-OH-B[b]F-9,10-diol) and trans-9,10-dihydro-6,9,10-trihydroxybenzo[b]fluoranthene (6-OH-B[b]F-9,10-diol) were synthesized and evaluated for tumor-initiating activity at initiation doses of 0.04, 0.12, and 0.4 mumol per mouse. In contrast to previous bioassay results, both of these phenolic dihydrodiols exhibited tumor-initiating activity. 5-OH-B[b]F-9,10-diol was the more potent tumor initiator, inducing a 90% incidence of tumor-bearing mice with an average of 7.50 tumors per mouse at a total initiator dose of 0.4 mumol. 6-OH-B[b]F-9,10-diol was significantly less active as a tumor initiator in this bioassay, inducing a 50% incidence of tumor-bearing mice with an average of 0.60 tumor per mouse at a total dose of 0.4 mumol. 32P-Postlabeling analysis was employed to evaluate the DNA adducts formed in vivo in mouse skin from both 5- and 6-OH-B[b]F-9,10-diol. HPLC analysis of B[b]F-DNA adducts formed in mouse skin demonstrated the presence of a single major adduct together with four additional minor adducts. The DNA adducts formed with 5-OH-B[b]F-9,10-diol had identical HPLC retention to the major and one of the minor adducts observed for B[b]F. These two DNA adducts account for 58% of the modified nucleotides detected in mouse skin following the topical application of B[b]F. Methods for the preparation of trans-9,10-dihydroxy-anti-11,12-epoxy-5-hydroxy-9,10,11,12- tetrahydrobenzo[b]fluoranthene (5-OH-B[b]F-9,10-DE) were developed. The DNA adducts formed with 5-OH-B[b]F-9,10-DE were similar to the adducts formed with 5-OH-B[b]F-9,10-diol. The results of the DNA binding studies along with the tumor-initiating data indicate that 5-OH-B[b]F-9,10-diol is the major proximate tumorigenic metabolite of B[b]F on mouse skin. Studies performed with deoxyguanosine 3'-phosphate suggest that the principal adducts formed with anti-5-OH-B[b]F-9,10-DE are the result of the interaction with deoxyguanosine.
College of Pharmacy, Rutgers, State University of New Jersey, Piscataway 08855-0789.
E H
EH
Weyand
Z W
ZW
Cai
Y
Y
Wu
J E
JE
Rice
Z M
ZM
He
E J
EJ
LaVoie
D000818:Animals; D002273:Carcinogens / Q000138:chemical synthesis* / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004247:DNA / Q000737:chemistry*; D003849:Deoxyguanosine / Q000737:chemistry; D005260:Female; D005449:Fluorenes / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D051379:Mice; D009153:Mutagens / Q000737:chemistry; D012867:Skin / Q000737:chemistry* / Q000378:metabolism; D012878:Skin Neoplasms / Q000139:chemically induced
D002273:Carcinogens; D005449:Fluorenes; D009153:Mutagens; C083261:9,10-dihydro-5,9,10-trihydroxybenzo(b)fluoranthene; C083260:9,10-dihydro-6,9,10-trihydroxybenzo(b)fluoranthene; D004247:DNA; C006703:benzo(b)fluoranthene; D003849:Deoxyguanosine