title: Mutation and overexpression of the transgene in ethylnitrosourea-induced tumors in mice carrying a human prototype c-Ha-ras gene.
abstract: 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.
authors.affiliation: Safety Research Laboratories, Dainippon Pharmaceutical Co, Ltd, Suita, Osaka 564-0053, Japan. kaoru-toyozawa@dainippon-pharm.co.jp
authors.forename: Kaoru
authors.initials: K
authors.lastname: Toyosawa
authors.forename: Kohji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Imai
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yasuhara
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Koujitani
authors.forename: Masao
authors.initials: M
authors.lastname: Hirose
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Mitsumori
mesh_terms: 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
chemical_list: D002273:Carcinogens; D003062:Codon; D012333:RNA, Messenger; D005038:Ethylnitrosourea