Release of sulfur mustard-modified DNA bases by Escherichia coli 3-methyladenine DNA glycosylase II.

The toxic effects of sulfur mustard have been attributed to DNA modification with the formation of 7-hydroxyethylthioethyl guanine, 3-hydroxyethylthioethyl adenine and the cross-link, di-(2-guanin-7-yl-ethyl)sulfide. To investigate the action of bacterial 3-methyladenine DNA glycosylase II (Gly II) on these adducts, calf thymus DNA was modified with [14C]sulfur mustard and used as a substrate for Gly II. Gly II releases both 3-hydroxyethylthioethyl adenine and 7-hydroxyethylthioethyl guanine from this substrate.

A 32P-postlabeling method for the detection of adducts in the DNA of human fibroblasts exposed to sulfur mustard.

Since the toxicities of sulfur mustard are attributed to DNA alkylation, levels of DNA modification in exposed cells should correlate with the intensity of exposure. We have found that 32P-postlabeling can be used successfully to detect the major adduct, 7-hydroxyethylthio- ethyldeoxyguanosine 5'-phosphate (HETEpdG), that is formed in DNA by sulfur mustard. This method has been used to establish a correlation between exposure and adduct formation in human fibroblasts grown in cell culture and exposed to sulfur mustard concentrations between 2.

A 32P-postlabeling method for detecting unstable N-7-substituted deoxyguanosine adducts in DNA.

Many antitumor agents, including the mustards, form N-7 deoxyguanosine adducts in DNA that are difficult to quantitate by the 32P-postlabeling procedure because of their instability. We have developed a method that is successful for the analysis of such adducts using, as a prototype mustard, 14C-labeled bis(2-chloroethyl)sulfide. This agent forms the unstable product 7-hydroxyethylthioethyldeoxyguanosine in DNA.

Detection of sulfur mustard-induced DNA modifications.

Sulfur mustard is acutely toxic to the skin, eyes, and respiratory tract, and is considered carcinogenic to humans by the IARC. Since all of these toxicities are thought to be initiated by DNA alkylation, the level of DNA damage should serve as a biomarker for exposure. To develop methods of detecting this damage, DNA was modified by [14C]-labeled sulfur mustard and DNA adducts were released by mild acid hydrolysis.