Mutation and overexpression of the transgene in ethylnitrosourea-induced tumors in mice carrying a human prototype c-Ha-ras gene.
To investigate mechanisms underlying accelerated carcinogenesis in mice carrying a human prototype c-Ha-ras gene (rasH2 mouse), mutations and the expression profile of the transgene were evaluated in 14 tumors induced by a single injection of ethylnitrosourea (ENU), with or without additional beta-estradiol 3-benzoate (EB) treatment. Although no codon 12 mutations were detected, changes in codon 61 were evident in all lung adenocarcinomas, skin squamous cell carcinomas and forestomach squamous cell carcinomas examined. The mRNA levels of the transgene in these lesions were also elevated 1.71- to 4.77-fold, 3.04- to 5.18-fold, and 3.00- to 5.67-fold, respectively, in comparison with those in the normal livers of rasH2 mice. The results obtained in this study suggest that mutations in codon 61 and amplification of the transgene play key roles in the carcinogenesis induced by ENU in rasH2 mice.
Toyosawa
Kaoru
K
Safety Research Laboratories, Dainippon Pharmaceutical Co, Ltd, Suita, Osaka 564-0053, Japan. kaoru-toyozawa@dainippon-pharm.co.jp
Tanaka
Kohji
K
Imai
Toshio
T
Yasuhara
Kazuo
K
Koujitani
Takatoshi
T
Hirose
Masao
M
Mitsumori
Kunitoshi
K
D000230:Adenocarcinoma / Q000139:chemically induced / Q000473:pathology; D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000473:pathology; D003062:Codon; D005038:Ethylnitrosourea / Q000633:toxicity*; D005260:Female; D015870:Gene Expression; D011905:Genes, ras; D006801:Humans; D008099:Liver / Q000378:metabolism; D008175:Lung Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D012333:RNA, Messenger / Q000032:analysis; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology; D019076:Transgenes
D002273:Carcinogens; D003062:Codon; D012333:RNA, Messenger; D005038:Ethylnitrosourea