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Detection of carcinogen-DNA adducts in human fetal tissues by the 32P-postlabeling procedure
C Hansen1, I Asmussen, H Autrup
1Laboratory of Environmental Carcinogenesis, Danish Cancer Society, Copenhagen.
Abstract:
Tobacco smoke contains a number of genotoxic compounds that are metabolized to their biologically active forms that subsequently react with cellular DNA to form covalently bound carcinogen-DNA adducts. Several analytical procedures have been developed to detect these adducts in human tissues. Using the nuclease P1-enhanced 32P-postlabeling procedure for bulky adducts, we have detected at least 24 adducts in DNA isolated from placenta and umbilical cord DNA. Adducts were detected in both smokers and nonsmokers, but the relative adduct level (RAL) was significantly higher in smokers (42.8, 8 cases) than in nonsmokers (19.7, 11 cases). The origin of the adducts in nonsmokers remains unknown. The adduct levels in artery DNA were significantly lower than in the vein and the placenta, and a paired nonparametric analysis showed a significant association between the adduct levels in the three tissues. Our results show a maternal transfer of carcinogens present in cigarette smoke to fetal tissues and show that the tissues can metabolize the carcinogens to their DNA binding metabolites. The presence of adducts in fetal tissues may be indicative of genomic damage and may predispose the individual for the development of a serious disease later in life.
Insights
Cigarette smoke carcinogens form DNA adducts in maternal and fetal tissues. Higher adduct levels were found in smokers, indicating potential genomic damage and disease risk in newborns.
Area of Science:
- Environmental Health
- Toxicology
- Molecular Biology
Background:
- Tobacco smoke contains genotoxic compounds metabolized into DNA-reactive forms.
- These metabolites form carcinogen-DNA adducts, biomarkers of exposure and potential carcinogenicity.
- Analytical methods are crucial for detecting these adducts in human tissues.
Purpose of the Study:
- To detect and quantify carcinogen-DNA adducts in maternal and fetal tissues.
- To investigate the association between smoking status and adduct levels.
- To explore the maternal transfer of tobacco smoke carcinogens to the fetus.
Main Methods:
- Utilized the nuclease P1-enhanced 32P-postlabeling assay for bulky DNA adducts.
- Analyzed DNA from placenta, umbilical cord, artery, and vein tissues.
- Compared adduct levels between smokers and nonsmokers.
Main Results:
- Detected at least 24 distinct DNA adducts in placental and umbilical cord DNA.
- Significantly higher relative adduct levels (RAL) in smokers (42.8) versus nonsmokers (19.7).
- Adduct levels were lower in arteries than veins and placenta, with significant correlations across tissues.
Conclusions:
- Demonstrated maternal transfer of cigarette smoke carcinogens to fetal tissues.
- Confirmed fetal tissue metabolic activation of carcinogens to DNA-binding forms.
- Suggests fetal adducts may indicate genomic damage, increasing future disease risk.