title: The rasH2 transgenic mouse: nature of the model and mechanistic studies on tumorigenesis.
abstract: The rasH2 mouse is a hemizygous transgenic mouse carrying the c-Ha-ras oncogene and that gene's promotor/enhancer within the genetic background of a BALB/cByJ x C57BL/6J F1 mouse. Approximately 3 copies of the transgene are integrated in a tandem array into chromosome number 15. The transgene is transmitted stably without point mutation in hot spots and is expressed in all tissues over 20 backcross generations. The homozygous c-Ha-ras genotype is lethal. Hemizygotes are selected by polymerase chain reaction (PCR) analysis of tail tips after birth. Spontaneous tumors in hemizygous transgenic mice are rare until 6 months of age. The observed rasH2 tumor spectrum, including lung adenoma/adenocarcinoma, forestomach and skin papillomas, Harderian gland adenoma, liver proliferative lesions, splenic hemangioma/sarcoma, and lymphoma is consistent with the BALB/c and C57BL/6 background. In the rasH2 mouse, point mutations of the transgene induced by genotoxins are reported frequently but not in all tumors. Elevated levels of transgene expression were detected in all genotoxin-induced tumors in the rasH2. Increased transgene expression was independent of the mutation rate in transgenic and endogenous ras genes. These observations suggest that the overexpression of transgenic c-Ha-ras is responsible for accelerated tumor development.
authors.affiliation: Tokai University School of Medicine, Central Institute for Experimental Animals, Miyamae, Kawasaki, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Tamaoki
mesh_terms: D000826:Animal Testing Alternatives; D000818:Animals; D001835:Body Weight; D015197:Carcinogenicity Tests / Q000379:methods*; D002273:Carcinogens / Q000633:toxicity; D004195:Disease Models, Animal; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras; D006579:Heterozygote; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009153:Mutagens / Q000633:toxicity; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology
chemical_list: D002273:Carcinogens; D009153:Mutagens