title: ras activation in human tumors and in animal model systems.
abstract: Environmental agents such as radiation and chemicals are known to cause genetic damage. Alterations in a limited set of cellular genes called proto-oncogenes lead to unregulated proliferation and differentiation. We have studied the role of the ras gene family in carcinogenesis using two different animal models. In one case, thymic lymphomas were induced in mice by either gamma or neutron radiation, and in the other, keratoacanthomas were induced in rabbit skin with dimethylbezanthracene. Human keratoacanthomas similar to the ones induced in rabbits were also analyzed. We found that different types of radiation such as gamma rays and neutrons, induced different point mutations in ras genes. A novel K-ras mutation in codon 146 has been found in thymic lymphomas induced by neutrons. Keratoacanthomas induced in rabbit skin by dimethylbenzanthracene show a high frequency of H-ras-activated genes carrying a mutation in codon 61. The same is observed in human keratoacanthomas, although mutations are in both the 12th and the 61st codons of the H-ras gene. H-ras activation is less frequent in human squamous cell carcinomas than in keratoacanthomas, suggesting that ras genes could play a role in vivo in differentiation as well as in proliferation.
authors.affiliation: Department of Pathology, New York University Medical Center, NY 10016.
authors.forename: M
authors.initials: M
authors.lastname: Corominas
authors.forename: S R
authors.initials: SR
authors.lastname: Sloan
authors.forename: J
authors.initials: J
authors.lastname: Leon
authors.forename: H
authors.initials: H
authors.lastname: Kamino
authors.forename: E W
authors.initials: EW
authors.lastname: Newcomb
authors.forename: A
authors.initials: A
authors.lastname: Pellicer
mesh_terms: D016475:3T3 Cells; D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics*; D004249:DNA Damage; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D004789:Enzyme Activation; D005260:Female; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D007636:Keratoacanthoma / Q000139:chemically induced / Q000235:genetics*; D008223:Lymphoma / Q000209:etiology / Q000235:genetics*; D051379:Mice; D009381:Neoplasms, Radiation-Induced / Q000235:genetics*; D009502:Neutrons; D016133:Polymerase Chain Reaction; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis / Q000235:genetics*; D011817:Rabbits; D012878:Skin Neoplasms / Q000139:chemically induced / Q000235:genetics*; D013953:Thymus Neoplasms / Q000209:etiology / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm; D015127:9,10-Dimethyl-1,2-benzanthracene; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)