Quantitation of benzo[a]pyrene-DNA adducts by postlabeling with 14C-acetic anhydride and accelerator mass spectrometry.
Quantitation of carcinogen-DNA adducts provides an estimate of the biologically effective dose of a chemical carcinogen reaching the target tissue. In order to improve exposure-assessment and cancer risk estimates, we are developing an ultrasensitive procedure for the detection of carcinogen-DNA adducts. The method is based upon postlabeling of carcinogen-DNA adducts by acetylation with 14C-acetic anhydride combined with quantitation of 14C by accelerator mass spectrometry (AMS). For this purpose, adducts of benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE) with DNA and deoxyguanosine (dG) were synthesized. The most promutagenic adduct of BPDE, 7R,8S,9R-trihydroxy-10S-(N(2)-deoxyguanosyl)-7,8,9, 10-tetrahydrobenzo[a]pyrene (BPdG), was HPLC purified and structurally characterized. Postlabeling of the BPdG adduct with acetic anhydride yielded a major product with a greater than 60% yield. The postlabeled adduct was identified by liquid chromatography-mass spectrometry as pentakis(acetyl) BPdG (AcBPdG). Postlabeling of the BPdG adduct with 14C-acetic anhydride yielded a major product coeluting with an AcBPdG standard. Quantitation of the 14C-postlabeled adduct by AMS promises to allow detection of attomolar amounts of adducts. The method is now being optimized and validated for use in human samples.
Goldman
R
R
Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. rg26@gunet.georgetown.edu
Day
B W
BW
Carver
T A
TA
Mauthe
R J
RJ
Turteltaub
K W
KW
Shields
P G
PG
D000089:Acetic Anhydrides / Q000737:chemistry*; D000107:Acetylation; D000818:Animals; D001564:Benzo(a)pyrene / Q000032:analysis*; D002250:Carbon Radioisotopes; D002274:Carcinogens, Environmental / Q000032:analysis*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D018736:DNA Adducts / Q000032:analysis*; D007553:Isotope Labeling / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods*; D013054:Spectrophotometry, Atomic
D000089:Acetic Anhydrides; D002250:Carbon Radioisotopes; D002274:Carcinogens, Environmental; D018736:DNA Adducts; C056612:benzo(a)pyrene-DNA adduct; C031800:acetic anhydride; D001564:Benzo(a)pyrene