Cellular transforming genes have been identified in a number of different tumor cell lines and tumor types. A significant number of these oncogenes belong to the ras gene family. The ras gene family consists of three closely related genes:H-ras, K-ras and N-ras which code for a related 21 kDa protein. Mutations in codon 12, 13 and 61 of one of the three ras genes convert these genes into acute oncogenes. The presence of H-ras gene mutaions has important prognostic implication in various tumors. Each genomic DNA was isolated from tumors induced by implantation with DMBA, or by treatment with DMBA-implantation/irradiation. When genome DNA was transfected into NIH 3T3 cells and investigated by two-step PCR-RFLP, the following results were concluded : 1. Transformation foci developed in two groups when the genome DNA of two experimental groups were transfected into NIH 3T3 cells. 2. Transformation efficiency was 0.01-0.02 foci/ DNA in the experimental group with the DMBA-implantation, 0.01-0.03 foci/ DNA in the experimental group with the DMBA-implantation/irradiation according to results of trasfection assay. 3. When the point mutation of H-ras gene was investigated by a two-step PCR-RFLP, there was 13.9%(5/36) in the experimental group with the DMBA implantation, 15.4%(6/39) in the experimental group with the DMBA-implantation/irradiation. 4. The point mutation in codon 12 and 61 of H-ras was 5.6%(2/36) and 8.3%(3/36) in the experimental group with the DMBA implantation. 5. The point mutation in codon 12 and 61 of H-ras gene was 7.7%(3/39) in the experimental group with the DMBA-implantation/irradiation.
9,10-Dimethyl-1,2-benzanthracene* ; Animals ; Cell Line, Tumor ; Codon ; DNA ; Genes, ras* ; Genome ; Humans ; NIH 3T3 Cells ; Oncogenes ; Point Mutation ; Rats* ; Salivary Glands*