[Forestomach carcinoma and hepatoma induced in mice and rats by N-3-methylbutyl-N-1-methylacetonylnitrosamine (MAMBNA)].

MAMBNA is a new N-nitroso compound isolated from Fusarium moniliforme-inoculated corn meal. In the present studies the carcinogenicity of MAMBNA is shown by the induction of forestomach carcinomas and liver tumors in mice and rats following the gastric intubation of this compound. Among 42 mice of Kunming (KM) stock treated with MAMBNA (10-20 mg/week), 22 showed epithelial hyperplasia of the esophagus, 29 papillomas and 4 squamous carcinomas in the forestomach, and there were 6 liver adenomas and 3 hepatomas. One mouse had forestomach carcinoma and carcinoma in the liver. Most tumors developed in mice receiving the treatment for 136-317 days, with a total dose of 210-670 mg (Table 1). No tumor was found in 12 controls observed for 239-357 days. In the experiment with 29 Wistar strain rats, administration of MAMBNA (20-120 mg/week) resulted in 11 epithelial hyperplasias in the lower esophagus, 14 atypical hyperplasias and papillomas, and 11 squamous carcinomas in the forestomach. The earliest forestomach carcinoma appeared in a rat treated for 454 days, receiving 4480 mg of MAMBNA, and the other 10 carcinomas occurred in animals treated for 518-640 days. Hyperplasia of liver cells was noted in 4 rats and liver adenoma in 7 and hepatocellular carcinoma in 8. Most hepatomas developed in rats treated for 480-640 days, and 5 rats had both forestomach carcinoma and hepatoma (Table 2). In 11 untreated rats observed for 411-644 days only one forestomach papilloma was noted.