Metabolism of an antineoplastic methylhydrazine derivative in a P815 mouse neoplasm.

Ten normally occurring methylated trace bases of cytoplasmic RNA extracted from P815 ascites cells were identified as thymine, 3-methylcytosine, 5-methylcytosine, jV2-methylguanine, JV2, A^-dimethylguanine, 1-methylguanine, 7-methylguanine, 1-methyladenine, 6-methyladenine, and jV*,yV6-dimethyladenine. When the carcinostatic drug, l-methyl-2-(p-isopropylcarbamoyl)benzylhydrazine hydrochloride (MBH) (NSC 77213), is injected into mice bearing P815 ascites, its TV-methyl group is partially oxidized and used via the C-l pool for the de novo synthesis of adenine and guanine, partially oxidized to C02, and partially used for methylation of RNA. Trace amounts of radioactive methylated purines, identified as 7-methylguanine (the major methylated base), thymine, 5-methylcy tosine, 1-methylguanine, and 1-methyladenine (tentatively), were identified in cytoplasmic RNA with likely predominance in transfer RNA of ascites cells 2 and 4 hr after i.p. injection of the labeled MBH to mice bearing P815 ascites. In experiments with 3Hand l4C-double-labeled