title: Identification of 4-(3-Pyridyl)-4-oxobutyl-2'-deoxycytidine Adducts Formed in the Reaction of DNA with 4-(Acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone: A Chemically Activated Form of Tobacco-Specific Carcinogens.
abstract: Metabolic activation of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK,1) andN'-nitrosonornicotine (NNN,2) results in the formation of 4-(3-pyridyl)-4-oxobutyl (POB)-DNA adducts, several of which have been previously identified both in vitro and in tissues of laboratory animals treated with NNK or NNN. However, 2'-deoxycytidine adducts formed in this process have been incompletely examined in previous studies. Therefore, in this study we prepared characterized standards for the identification of previously unknown 2'-deoxycytidine and 2'-deoxyuridine adducts that could be produced in these reactions. The formation of these products in reactions of 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc,3), a model 4-(3-pyridyl)-4-oxobutylating agent, with DNA was investigated. The major 2'-deoxycytidine adduct, identified as its stable cytosine analogueO2-[4-(3-pyridyl)-4-oxobut-1-yl]-cytosine (12), wasO2-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine (13), whereas lesser amounts of 3-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine (14) andN4-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxycytidine (15) were also observed. The potential conversion of relatively unstable 2'-deoxycytidine adducts to stable 2'-deoxyuridine adducts by treatment of the adducted DNA with bisulfite was also investigated, but the harsh conditions associated with this approach prevented quantitation. The results of this study provide new validated standards for the study of 4-(3-pyridyl)-4-oxobutylation of DNA, a critical reaction in the carcinogenesis by1and2, and demonstrate the presence of previously unidentified 2'-deoxycytidine adducts in this DNA.
authors.affiliation: Masonic Cancer Center, University of Minnesota , 2231 6th Street SE, Room 2-148 CCRB, Minneapolis, Minnesota 55455, United States.
authors.forename: Anna K
authors.initials: AK
authors.lastname: Michel
authors.affiliation: Masonic Cancer Center, University of Minnesota , 2231 6th Street SE, Room 2-148 CCRB, Minneapolis, Minnesota 55455, United States.
authors.forename: Adam T
authors.initials: AT
authors.lastname: Zarth
authors.affiliation: Masonic Cancer Center, University of Minnesota , 2231 6th Street SE, Room 2-148 CCRB, Minneapolis, Minnesota 55455, United States.
authors.forename: Pramod
authors.initials: P
authors.lastname: Upadhyaya
authors.affiliation: Masonic Cancer Center, University of Minnesota , 2231 6th Street SE, Room 2-148 CCRB, Minneapolis, Minnesota 55455, United States.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Hecht