Carcinogenesis Advance Access originally published online on August 21, 2006
Carcinogenesis 2007 28(2):342-349; doi:10.1093/carcin/bgl142
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Detection and quantification of 4-ABP adducts in DNA from bladder cancer patients
1 Universidad Metropolitana, San Juan, Puerto Rico MA, USA
2 Biological Engineering Division, Massachusetts Institute of Technology, Cambridge MA, USA
3 Chemistry Department, Massachusetts Institute of Technology, Cambridge MA, USA
4 The Cancer Center, University of Minnesota Minneapolis, MN, USA
*To whom correspondence should be addressed. Email: ljtrudel{at}mit.edu
We analyzed bladder DNA from 27 cancer patients for dG-C8-4-aminobiphenyl (dG-C8-ABP) adducts using the liquid chromatography tandem mass spectrometry method with a 700 attomol (1 adduct in 109 bases) detection limit. Hemoglobin (Hb) 4-aminobiphenyl (4-ABP) adduct levels were measured by gas chromatography-mass spectrometry. After isolation of dG-C8-ABP by immunoaffinity chromatography and further purification, deuterated (d9) dG-C8-ABP (MW = 443 Da) was added to each sample. Structural evidence and adduct quantification were determined by selected reaction monitoring, based on the expected adduct ion [M+H+]+1, at m/z 435 with fragmentation to the product ion at m/z 319, and monitoring of the transition for the internal standard, m/z 444 
328. The method was validated by analysis of DNA (100 µg each) from calf thymus; livers from ABP-treated and untreated rats; human placentas; and TK6 lymphoblastoid cells. Adduct was detected at femtomol levels in DNA from livers of ABP-treated rats and calf thymus, but not in other controls. The method was applied to 41 DNA samples (200 µg each) from 27 human bladders; 28 from tumor and 14 from surrounding non-tumor tissue. Of 27 tissues analyzed, 44% (12) contained 5–80 dG-C8-ABP adducts per 109 bases; only 1 out of 27 (4%) contained adduct in both tumor and surrounding tissues. The Hb adduct was detected in samples from all patients, at levels of 12–1960 pg per gram Hb. There was no correlation between levels of DNA and Hb adducts. The presence of DNA adducts in 44% of the subjects and high levels of Hb adducts in these non-smokers indicate environmental sources of exposure to 4-ABP.
Abbreviations: 4-ABP, 4-aminobiphenyl; acetyl cyanide, pyruvonitrile; d9-dG-C8-ABP, deuterated dG-C8-4-ABP; dG-C8-ABP, dG-C8-4-aminobiphenyl; DMAC, dimethylacetamide; GC/MS, gas chromatography-mass spectrometry; LC/MS, liquid chromatography mass spectrometry; LC/MS/MS, liquid chromatography tandem mass spectrometry; SRM, selected reaction monitoring
Received April 12, 2006; revised July 7, 2006; accepted August 1, 2006.