title: The raf oncogene is associated with a radiation-resistant human laryngeal cancer.
abstract: In order to identify the genetic factors associated with the radiation-resistant human laryngeal carcinoma cell line (SQ-20B), tumor cell DNA was transfected into NIH/3T3 cells. A high incidence (six out of six) of raf sequences was found in transfected NIH/3T3 clones and the tumorigenic potential of SQ-20B DNA could be linked to genomic fragments that represent most of the kinase domain of human c-raf-1. An apparently unaltered 3.5-kilobase pair (kb) human c-raf transcript was identified in SQ-20B cells but was not observed in the transfected NIH/3T3 cell clones. Two new transcripts (4.2 kb and 2.6 kb) were found in tumorigenic clones; the large transcript was missing in a very poorly tumorigenic clone. Cytogenetic analysis indicated that the normal autosomes of chromosome 3 were absent in SQ-20B karyotypes and had formed apparently stable marker chromosomes. Unlike the recipient NIH/3T3 cell line, 30 percent of the transformed clone-1 metaphases had minute and double-minute chromosomes representative of amplified DNA sequences. The frequency of the c-raf-1 identification by NIH/3T3 transfection of SQ-20B DNA suggests the presence of some genetic abnormality within this locus.
mesh_terms: D000818:Animals; D002460:Cell Line; D004273:DNA, Neoplasm / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D007822:Laryngeal Neoplasms / Q000235:genetics* / Q000532:radiotherapy; D051379:Mice; D008819:Mice, Nude; D009693:Nucleic Acid Hybridization; D009857:Oncogenes / Q000528:radiation effects*; D011519:Proto-Oncogenes / Q000528:radiation effects; D011836:Radiation Tolerance
chemical_list: D004273:DNA, Neoplasm