N-methyl-N-nitrosourea concentration-dependent, rather than total intake-dependent, induction of adenocarcinomas in the glandular stomach of BALB/c mice

Takasuke Yamachika, Hayao Nakanishi, Ken Ichi Inada, Tetsuya Tsukamoto, Nobuyuki Shimizu, Kiyoshi Kobayashi, Shoji Fukushima, Masae Tatematsu

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35 Citations (Scopus)

Abstract

The influence of the level of carcinogen exposure on histopathological types and cellular differentiation of the induced tumours was examined in 100 male BALB/c mice given N-methyl-N-nitrosourea (MNU) in their drinking water at 240 ppm on alternate weeks (total exposure: five weeks) (group 1), at 120 ppm similarly (total exposure: ten weeks ) (group 2), at 60 ppm for 20 weeks continously (group 3), or at 30 ppm for 40 weeks continously (group 4). Forty-three differentiated and 17 undifferentiated type adenocarcinomas were induced. Glandular stomach carcinomas and undifferentiated type lesions were more common in mice treated with a high concentration of MNU for a short period than with a low concentration of MNU for a long period, even though total measured intake of MNU was smaller (P < 0.01). All the induced glandular stomach carcinomas, independent of the treatment schedule, consisted entirely of gastric phenotype cells. In conclusion, the induction of glandular stomach cancers and the proportion of undifferentiated type lesions depend not on the total quantity, but rather on the concentration of the carcinogen, while the phenotypic expression of tumor cells is not affected by the differences in the administration protocol.

Original languageEnglish
Pages (from-to)385-391
Number of pages7
JournalJapanese Journal of Cancer Research
Volume89
Issue number4
DOIs
Publication statusPublished - 04-1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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