Oncogene Alterations in In vitro Transformed Rat Tracheal Epithelial Cells

摘要

Ten derivations of rat tracheal epithelial (RTE) cells, including normal cells, normal primary cultures, 7 tumorigenic cell lines and 1 non-tumorigenic cell line transformed in vitro by treatment with 7,12-dimethylbenz(a)anthracene (DMBA), benzo(a)pyrene and/or 12-O-tetradecanoylphorbol-13-acetate (TPA) were examined for oncogene alterations. The analyses included amplification, restriction length polymorphisms (RFLPs), and changes in the expression of RNA transcripts of Ha-ras, Ki-ras, and c-myc. Two DMBA-derived cell lines displayed RFLPs after Eco RI digestion and probing for Ki-ras. No abnormalities of Ha-ras were seen after digestion with Bam HI, Eco RI, or Hind III. No extra Pst I (Ha-ras codon 12, GGA to CGA) or Xba I (Ha-ras codon 61, CAA to CTA) sites were seen after probing for Ha-ras. In one cell line derived by DMBA-treatment, changes in the c-myc restriction pattern were seen after digestion with Bam HI and Hind III. Analysis of CCGG sequences by Hpa II/Msp I digestion indicated that Ki-ras was highly methylated, Ha-ras exhibited limited methylation, and c-myc CCGG sequences were not methylated. In addition, normal cells removed from tracheas and those in primary cultures displayed Hpa II digestion patterns that were distinguishable from those of transformed cell lines by the presence of an apparent extra methylation site. (Copyright (c) 1990 Elsevier Science Publishers B.V. (Biomedical Division).)