Rapid emergence of mammary preneoplastic and malignant lesions in human c-Ha-ras proto-oncogene transgenic rats: possible application for screening of chemopreventive agents.
For comparison of mammary gland whole mounts with examination of 2 histologic sections of mammary gland, 56 Hras128 rats were intravenously injected with 50 mg/kg body weight of N-methyl-N-nitrosourea at 50 days of age and then sacrificed at days 5, 10, 15, 20, 25, and 56. Comparison of detection sensitivity between the whole mounts and histologic sections revealed no lesions apparent in whole mounts on day 10, although intraductal proliferation was clearly detected in histologic sections in 44% of treated rats. Proliferative lesions were first detected in whole mounts at a 44% incidence on day 15, while intraductal proliferations and atypical hyperplasias were apparent in the sections at 89% and 44% incidences, respectively. On day 20, atypical hyperplasias and small adenocarcinomas in histologic sections were found in almost all animals. In conclusion, examination of 2 histologic sections from mammary tissues was found to be practical for detection of small malignant lesions as early as 15 days after MNU injection, and suppressive effects of soy isoflavones were clearly evident within 20 days after carcinogen exposure. These results suggest that this model has practical utility for short-term screening of chemopreventive agents for mammary carcinogenesis.
Experimental Pathology and Chemotherapy Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
Yoichiro
Y
Matsuoka
Katsumi
K
Fukamachi
Tetsuya
T
Hamaguchi
Hiroyasu
H
Toriyama-Baba
Hiroaki
H
Kawaguchi
Masato
M
Kusunoki
Hiroki
H
Yoshida
Hiroyuki
H
Tsuda
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D000818:Animals; D030801:Animals, Genetically Modified; D000970:Antineoplastic Agents / Q000008:administration & dosage; D018890:Chemoprevention; D004354:Drug Screening Assays, Antitumor / Q000379:methods*; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage; D015674:Mammary Neoplasms, Animal / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D008770:Methylnitrosourea / Q000633:toxicity; D011230:Precancerous Conditions / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D000090063:Proto-Oncogene Mas; D051381:Rats
D000970:Antineoplastic Agents; D007529:Isoflavones; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D008770:Methylnitrosourea