Quantification of Hemoglobin and White Blood Cell DNA Adducts of the Tobacco Carcinogens 2-Amino-9H-pyrido[2,3-b]indole and 4-Aminobiphenyl Formed in Humans by Nanoflow Liquid Chromatography/Ion Trap Multistage Mass Spectrometry

Chem Res Toxicol. 2017 Jun 19;30(6):1333-1343. doi: 10.1021/acs.chemrestox.7b00072. Epub 2017 May 25.

Abstract

Aromatic amines covalently bound to hemoglobin (Hb) as sulfinamide adducts at the cysteine 93 residue of the Hb β chain have served as biomarkers to assess exposure to this class of human carcinogens for the past 30 years. In this study, we report that 2-amino-9H-pyrido[2,3-b]indole (AαC), an abundant carcinogenic heterocyclic aromatic amine formed in tobacco smoke and charred cooked meats, also reacts with Hb to form a sulfinamide adduct. A novel nanoflow liquid chromatography/ion trap multistage mass spectrometry (nanoLC-IT/MS3) method was established to assess exposure to AαC and the tobacco-associated bladder carcinogen 4-aminobiphenyl (4-ABP) through their Hb sulfinamide adducts. Following mild acid hydrolysis of Hb in vitro, the liberated AαC and 4-ABP were derivatized with acetic anhydride to form the N-acetylated amines, which were measured by nanoLC-IT/MS3. The limits of quantification (LOQ) for AαC- and 4-ABP-Hb sulfinamide adducts were ≤7.1 pg/g Hb. In a pilot study, the mean level of Hb sulfinamide adducts of AαC and 4-ABP were, respectively, 3.4-fold and 4.8-fold higher in smokers (>20 cigarettes/day) than nonsmokers. In contrast, the major DNA adducts of 4-ABP, N-(2'-deoxyguanosin-8-yl)-4-aminobiphenyl, and AαC, N-(2'-deoxyguanosin-8-yl)-2-amino-9H-pyrido[2,3-b]indole, were below the LOQ (3 adducts per 109 bases) in white blood cell (WBC) DNA of smokers and nonsmokers. These findings reaffirm that tobacco smoke is a major source of exposure to AαC. Hb sulfinamide adducts are suitable biomarkers to biomonitor 4-ABP and AαC; however, neither carcinogen binds to DNA in WBC, even in heavy smokers, at levels sufficient for biomonitoring.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aminobiphenyl Compounds / chemistry*
  • Carbolines / chemistry*
  • Carcinogens / chemistry*
  • Chromatography, High Pressure Liquid
  • DNA Adducts / analysis*
  • DNA Adducts / chemistry
  • Hemoglobins / analysis
  • Hemoglobins / chemistry*
  • Humans
  • Leukocytes / metabolism*
  • Mass Spectrometry
  • Molecular Structure
  • Nanotechnology
  • Nicotiana / chemistry*
  • Sulfamerazine / analysis
  • Sulfamerazine / chemistry

Substances

  • Aminobiphenyl Compounds
  • Carbolines
  • Carcinogens
  • DNA Adducts
  • Hemoglobins
  • sulfenamide
  • 4-biphenylamine
  • 2-amino-9H-pyrido(2,3-b)indole
  • Sulfamerazine