Immuno-slot-blot: a highly sensitive immunoassay for the quantitation of carcinogen-modified nucleosides in DNA.
We have established a highly sensitive immuno-slot-blot (ISB) procedure that can be routinely applied for detection and quantitation of any heat- or alkali-stable structural DNA modification (caused by carcinogens or mutagens, for example) for which a specific (monoclonal) antibody (MAB) is available. The essential step in this assay is the immobilization on nitrocellulose filters of the structurally modified DNA in its single-stranded form. The immobilized DNA is first reacted with an MAB specifically directed against a particular modified DNA component (e.g., an alkyldeoxynucleoside), and thereafter with a second antibody directed against the first one. The second antibody can be either labeled with 125I or linked to an enzyme complex capable of eliciting a color reaction with a suitable substrate. The sensitivity of the ISB is demonstrated for two different alkyldeoxynucleosides, O6-ethyldeoxyguanosine (O6-EtdGuo) and O4-ethyldeoxythymidine (O4-EtdThd), both of which are produced in cellular DNA exposed to the alkylating N-nitroso carcinogen N-ethyl-N-nitrosourea and both of which represent DNA lesions miscoding during DNA replication and transcription. Using anti-(O6-EtdGuo) and anti-(O4-EtdThd) MABs, respectively, O6-EtdGuo and O4-EtdThd are detected at levels as low as greater than or equal to 0.3 X 10(-15) mol O6-EtdGuo/3 micrograms DNA (O6-EtdGuo/deoxyguanosine molar ratio in DNA, greater than or equal to 2 X 10(-7) ) and greater than or equal to 0.1 X 10(-15) mol of O4-EtdThd/3 micrograms DNA (O4-EtdThd/deoxythymidine molar ratio in DNA, greater than or equal to 4 X 10(-8) ).
D000478:Alkylation; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002273:Carcinogens; D004247:DNA / Q000032:analysis*; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D005260:Female; D007118:Immunoassay / Q000379:methods*; D009705:Nucleosides / Q000032:analysis*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
D000911:Antibodies, Monoclonal; D002273:Carcinogens; D009705:Nucleosides; C018534:O(6)-ethyl-2'-deoxyguanosine; D004247:DNA; D003849:Deoxyguanosine