Association between cigarette smoking and urinary excretion of 1,N2-ethenoguanine measured by isotope dilution liquid chromatography-electrospray ionization/tandem mass spectrometry.
Levels of the promutagenic 1,N2-ethenoguanine (1,N2-epsilonGua), an etheno DNA adduct derived mainly from lipid peroxidation, in experimental animals are associated with risk of cancer formation. Since 1,N2-epsilonGua can be repaired by human glycosylases, it is possible to use it as a biomarker for cancer risk assessment in humans. In the present study, a highly sensitive and specific stable isotope dilution liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/MS) was developed for accurate quantification of 1,N2-epsilonGua in human urine. The sample pretreatment involved a consecutive strong cation exchange solid-phase extraction (SPE) and reversed phase SPE chromatography. The pretreated sample was analyzed by LC-ESI/MS/MS under multiple reaction monitoring mode (MRM) using a triple quadrupole mass spectrometer. The detection limit of 1,N2-epsilonGua using this LC-ESI/MS/MS assay was 1.0 pg (5.8 fmol) injected on-column. Levels of urine samples collected from healthy volunteers were found to range from 0 to 199 pg/mL, and levels as low as 5.0 pg/mL (29 pM) could be accurately quantified. After adjusting for creatinine levels and body weight, an statistically significant association was observed between urinary levels of 1,N2-epsilonGua and cigarette smoking (p = 0.0006). This highly specific and sensitive assay should be valuable in measuring urinary 1,N2-epsilonGua as a potential noninvasive biomarker for oxidative DNA damage.
Department of Chemistry and Biochemistry, National Chung Cheng University, 168 University Road, Ming-Hsiung, Chia-Yi 62142, Taiwan. chehjc@ccu.edu.tw
Hauh-Jyun Candy
HJ
Chen
Wei-Loong
WL
Chiu
D000328:Adult; D015415:Biomarkers / Q000652:urine; D002853:Chromatography, Liquid / Q000379:methods*; D018736:DNA Adducts / Q000652:urine*; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives* / Q000652:urine; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012907:Smoking / Q000652:urine*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D015415:Biomarkers; D018736:DNA Adducts; C085534:1,(N2)-ethenoguanine; D006147:Guanine