Similar rate of O6-ethylguanine elimination from DNA in normal human fibroblast and xeroderma pigmentosum cell strains not transformed by SV40.

Using a highly specific rabbit antiserum (E3) directed against O6-ethyldeoxyguanosine in a competitive radioimmunoassay, we have measured the kinetics of removal of this alkylation product from the DNA of human fibroblasts treated with the N-nitroso carcinogen N-ethyl-N-nitrosourea. A very similar rate of elimination from DNA was found in two normal human fibroblast strains (GM730 and 54BR) and in the nonvirus-transformed xeroderma pigmentosum fibroblast strains XP2BI and XP3BR. This is in contrast to the SV40-transformed xeroderma pigmentosum fibroblast strain XP12RO-SV40 which had previously been shown to be defective in its ability to remove O6-ethylguanine from DNA.