title: X-ray-induced changes in gene expression in normal and oncogene-transformed rat cell lines.
abstract: As an approach to identifying specific cellular markers for the cytotoxic action of x rays in mammalian cells, we used the QUEST system of high-resolution, two-dimensional protein gel electrophoresis and a computerized data base on proteins to score quantitative changes in patterns of protein synthesis. We measured the responses elicited after x irradiation of cells from the normal rat cell line REF52 as well as two oncogene-transformed REF52 cell lines with E1a or E1a plus the mutated c-Harvey-ras T24 (HRAS1 T24) allele. The transformed cell lines differed substantially in the patterns of changes in protein synthesis seen immediately after DNA damage. In addition, we identified a specific subset of growth-regulated cellular polypeptides that are correlated with the observed increase in x-ray-induced cell killing in the transformed cell lines. One of these polypeptides was cyclin (proliferating-cell nuclear antigen), a cell-cycle-specific DNA polymerase delta auxiliary factor. Synthesis of this set of coregulated polypeptides was rapidly suppressed by x irradiation in normal REF52 cells only. The inability of x irradiation to induce suppression of protein synthesis in cells from the transformed cell lines correlated with the increased susceptibility to x-ray-induced cell killing. This finding suggests that the cellular processes that underlie regulation of DNA-damage-induced growth arrest at the level of replicative elongation plays a role in determining the survival of x-irradiated cells.
mesh_terms: D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects*; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D015180:Electrophoresis, Gel, Two-Dimensional; D007256:Information Systems; D009687:Nuclear Proteins / Q000096:biosynthesis; D009857:Oncogenes; D018809:Proliferating Cell Nuclear Antigen; D051381:Rats; D014158:Transcription, Genetic
chemical_list: D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D004247:DNA