title: Activation of the cellular Harvey ras gene in mouse skin tumors initiated with urethane.
abstract: Mouse skin tumors, benign papillomas, and squamous cell carcinomas (SCCs) were initiated by a single topical application of urethane followed by repeated promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA). Using the NIH 3T3 focus forming assay, dominant transforming activity was detected in DNA isolated from SCC samples. Rearranged and amplified copies of the c-Ha-ras gene were detected in NIH 3T3 transformant cell lines, indicating that an activated Ha-ras gene had been transferred to the NIH 3T3 recipient cells. Analysis of p21ras from the transformant cell lines suggested that the activating ras mutation was present in codon 61. Ultimately, the Ha-ras gene was shown to be activated by a specific A----T transversion at the second position of codon 61. This mutation was detected in both benign papillomas and SCCs, suggesting the activation occurred early in tumor development. The results demonstrate a highly consistent activation of the Ha-ras oncogene by a specific point mutation, suggesting a functional role for an activated ras gene in the initiation of mouse skin tumors by urethane.
authors.affiliation: Radiation Oncology Department, University of Arizona Health Sciences Center, Tucson 85724.
authors.forename: K
authors.initials: K
authors.lastname: Bonham
authors.forename: T
authors.initials: T
authors.lastname: Embry
authors.forename: D
authors.initials: D
authors.lastname: Gibson
authors.forename: D R
authors.initials: DR
authors.lastname: Jaffe
authors.forename: R A
authors.initials: RA
authors.lastname: Roberts
authors.forename: A E
authors.initials: AE
authors.lastname: Cress
authors.forename: G T
authors.initials: GT
authors.lastname: Bowden
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics*; D002471:Cell Transformation, Neoplastic; D003043:Cocarcinogenesis; D003062:Codon; D015342:DNA Probes; D005784:Gene Amplification; D011905:Genes, ras; D051379:Mice; D009154:Mutation; D010212:Papilloma / Q000139:chemically induced / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D011518:Proto-Oncogene Proteins / Q000032:analysis; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate; D014410:Tumor Stem Cell Assay; D014520:Urethane
chemical_list: D003062:Codon; D015342:DNA Probes; D011518:Proto-Oncogene Proteins; D014520:Urethane; D013755:Tetradecanoylphorbol Acetate