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Methylation of DNA in target and non‐target organs of the rat with methylbenzylnitrosamine and dimethylnitrosamine
Author(s) -
Fong Louise Y. Y.,
Lin Hsiang Ju,
Lee Clara Lai Hing
Publication year - 1979
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910230514
Subject(s) - carcinogen , guanine , dna , labelling , chemistry , methylation , biochemistry , purine metabolism , dna methylation , microbiology and biotechnology , nitrosamine , in vitro , ap site , dna damage , biology , enzyme , nucleotide , gene , gene expression
The sites of labelling of DNA with [ 14 C]methyl groups from methylbenzylnitrosamine and dimethylnitrosamine were studied in rat oeso‐phageal epithelium and liver. All four combinations of tissue and carcinogen were studied. Tissues were labelled in vitro and the DNA contained therein purified and hydrolysed (pH 1, 37° C) to free purines and apurinic acid. Quantitative analysis was performed with the aid of thin‐layer chromatography. The apurinic acid and 7‐methylguanine fractions were found to be extensively labelled. Smaller amounts of radioactivity were found in O 6 ‐methyl‐guanine and some of the methylated adenines. The same carcinogen produced different patterns of labelling in oesophageal and liver DNA. The proportion of O 6 ‐methylguanine to 7‐methylguanine was higher when the methylating agent was a carcinogen specific for the organ.