title: Measurement of Endogenous versus Exogenous Formaldehyde-Induced DNA-Protein Crosslinks in Animal Tissues by Stable Isotope Labeling and Ultrasensitive Mass Spectrometry.
abstract: DNA-protein crosslinks (DPC) arise from a wide range of endogenous and exogenous chemicals, such as chemotherapeutic drugs and formaldehyde. Importantly, recent identification of aldehydes as endogenous genotoxins in Fanconi anemia has provided new insight into disease causation. Because of their bulky nature, DPCs pose severe threats to genome stability, but previous methods to measure formaldehyde-induced DPCs were incapable of discriminating between endogenous and exogenous sources of chemical. In this study, we developed methods that provide accurate and distinct measurements of both exogenous and endogenous DPCs in a structurally specific manner. We exposed experimental animals to stable isotope-labeled formaldehyde ([(13)CD2]-formaldehyde) by inhalation and performed ultrasensitive mass spectrometry to measure endogenous (unlabeled) and exogenous ((13)CD2-labeled) DPCs. We found that exogenous DPCs readily accumulated in nasal respiratory tissues but were absent in tissues distant to the site of contact. This observation, together with the finding that endogenous formaldehyde-induced DPCs were present in all tissues examined, suggests that endogenous DPCs may be responsible for increased risks of bone marrow toxicity and leukemia. Furthermore, the slow rate of DPC repair provided evidence for the persistence of DPCs. In conclusion, our method for measuring endogenous and exogenous DPCs presents a new perspective for the potential health risks inflicted by endogenous formaldehyde and may inform improved disease prevention and treatment strategies. Cancer Res; 76(9); 2652-61. ©2016 AACR.
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Lai
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Rui
authors.initials: R
authors.lastname: Yu
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Hadley J
authors.initials: HJ
authors.lastname: Hartwell
authors.affiliation: Lovelace Respiratory Research Institute, Albuquerque, New Mexico.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Moeller
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Wanda M
authors.initials: WM
authors.lastname: Bodnar
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. jswenber@email.unc.edu.
authors.forename: James A
authors.initials: JA
authors.lastname: Swenberg
mesh_terms: D000818:Animals; D003432:Cross-Linking Reagents / Q000633:toxicity*; D004249:DNA Damage; D005557:Formaldehyde / Q000633:toxicity*; D007553:Isotope Labeling / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods*; D051381:Rats
chemical_list: D003432:Cross-Linking Reagents; D005557:Formaldehyde