Metabolic fate of endogenous molecular damage: Urinary glutathione conjugates of DNA-derived base propenals as markers of inflammation.
Although mechanistically linked to disease, cellular molecules damaged by endogenous processes have not emerged as significant biomarkers of inflammation and disease risk, due in part to poor understanding of their pharmacokinetic fate from tissue to excretion. Here, we use systematic metabolite profiling to define the fate of a common DNA oxidation product, base propenals, to discover such a biomarker. Based on known chemical reactivity and metabolism in liver cell extracts, 15 candidate metabolites were identified for liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) quantification in urine and bile of rats treated with thymine propenal (Tp). Analysis of urine revealed three metabolites (6% of Tp dose): thymine propenoate and two mercapturate derivatives of glutathione conjugates. Bile contained an additional four metabolites (22% of Tp dose): cysteinylglycine and cysteine derivatives of glutathione adducts. A bis-mercapturate was observed in urine of untreated rats and increased approximately three- to fourfold following CCl4-induced oxidative stress or treatment with the DNA-cleaving antitumor agent, bleomycin. Systematic metabolite profiling thus provides evidence for a metabolized DNA damage product as a candidate biomarker of inflammation and oxidative stress in humans.
Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
Watthanachai
W
Jumpathong
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong;
Wan
W
Chan
Center for Environmental Health Science, Massachusetts Institute of Technology, Cambridge, MA 02139.
Koli
K
Taghizadeh
Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
I Ramesh
IR
Babu
Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Center for Environmental Health Science, Massachusetts Institute of Technology, Cambridge, MA 02139 pcdedon@mit.edu.
Peter C
PC
Dedon
D000475:Alkenes / Q000378:metabolism*; D000818:Animals; D001646:Bile / Q000378:metabolism; D015415:Biomarkers / Q000652:urine*; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D005260:Female; D005978:Glutathione / Q000652:urine*; D007249:Inflammation / Q000652:urine*; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley
D000475:Alkenes; D015415:Biomarkers; D004247:DNA; C013658:propylene; D005978:Glutathione
DNA damage; biomarker; mass spectrometry; metabolism; oxidative stress