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Detection of 1,N6-etheno-2'-deoxyadenosine and 3,N4-etheno-2'-deoxycytidine occurring endogenously in DNA
W P Watson1, J P Aston, T Barlow
1Toxicology Department, Shell International Chemicals BV, Shell Research and Technology Centre, Amsterdam, The Netherlands.
IARC Scientific Publications
|January 8, 2000
Summary
Researchers developed sensitive methods to detect DNA adducts like 1,N6-etheno-2'-deoxyadenosine (epsilon dA) and 3,N4-etheno-2'-deoxycytidine (epsilon dC). This helps understand chemical exposure risks by comparing them to natural background levels.
Area of Science:
- Biochemistry
- Toxicology
- Molecular Biology
Background:
- 1,N6-Etheno-2 -deoxyadenosine (epsilon dA) and 3,N4-etheno-2 -deoxycytidine (epsilon dC) are DNA adducts formed by genotoxic chemicals and endogenous processes.
- Understanding the endogenous formation of these adducts is crucial for contextualizing chemical exposure risks, such as from vinyl chloride.
- Sensitive analytical methods are needed to quantify these adducts at background levels.
Purpose of the Study:
- To develop and validate sensitive methods for detecting endogenous 1,N6-etheno-2 -deoxyadenosine (epsilon dA) and 3,N4-etheno-2 -deoxycytidine (epsilon dC) DNA adducts.
- To compare adduct levels in control rats with those exposed to vinyl chloride.
- To explore immunochemical approaches for etheno-DNA adduct detection.
Main Methods:
- High-performance liquid chromatography (HPLC) with 32P-postlabelling was employed for sensitive adduct detection.
- HPLC-32P-postlabelling was used to analyze liver DNA from control and vinyl chloride-exposed Wistar rats.
- Immunochemical methods, including monoclonal antibodies and immunoaffinity enrichment coupled with capillary zone electrophoresis, were developed.
Main Results:
- The HPLC-32P-postlabelling method detected epsilon dA and epsilon dC in control rat liver DNA at frequencies of 1 adduct in 8.1 x 10^7 and 1 adduct in 1.8 x 10^7 nucleotides, respectively.
- Vinyl chloride exposure increased adduct levels to 1 adduct in 2.9 x 10^7 (epsilon dA) and 1 adduct in 1.4 x 10^7 (epsilon dC) nucleotides.
- Immunochemical methods demonstrated high selectivity, resolving approximately one epsilon dC adduct in 3 x 10^6 nucleotides when coupled with capillary electrophoresis.
Conclusions:
- Sensitive HPLC-32P-postlabelling and immunochemical methods can quantify endogenous and chemically induced etheno-DNA adducts.
- These methods provide a critical baseline for assessing the risk associated with genotoxic chemical exposure.
- Immunochemical techniques offer a promising avenue for highly sensitive and selective detection of specific DNA adducts.