title: Reduced synthesis of pp60src and expression of the transformation-related phenotype in interferon-treated Rous sarcoma virus-transformed rat cells.
abstract: Treatment of Rous sarcoma virus-transformed rat cells with rat interferon-alpha (specific activity, 10(6) U/mg of protein) for 24 h caused a 50% reduction in intracellular pp60src-associated protein kinase activity. Staphylococcus aureus V8 protease digestion of pp60src, derived from 32P-labeled monolayer cultures incubated with or without interferon, revealed no differences either in the phosphopeptide pattern or in the phosphoserine-phosphotyrosine ratio. However, [3H]leucine pulse-labeling experiments showed that the synthesis of pp60src was reduced by 42 to 48%, relative to the level of bulk protein synthesis, in the interferon-treated cultures. Rat interferon-alpha also reduced the growth rate of Rous sarcoma virus-transformed rat cells in a dose-dependent manner over a 72-h period. The decrease in growth rate was accompanied by increases in the thickness and number of actin fibers per cell and by a decline in intracellular tyrosine phosphorylation by pp60src. The results suggest that interferon can inhibit the expression of the transformation-related phenotype by selectively reducing the synthesis of the Rous sarcoma virus transforming gene product. However, the interferon effects on the cytoskeletal organization and proliferation of Rous sarcoma virus-transformed cells may be due at least in part to the predominance of interferon-induced phenotypic changes over those caused by pp60src.
mesh_terms: D000199:Actins / Q000096:biosynthesis; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002472:Cell Transformation, Viral / Q000187:drug effects*; D007370:Interferon Type I / Q000494:pharmacology*; D015688:Oncogene Protein pp60(v-src); D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D014443:Tyrosine / Q000378:metabolism; D014764:Viral Proteins / Q000096:biosynthesis*
chemical_list: D000199:Actins; D007370:Interferon Type I; D014764:Viral Proteins; D014443:Tyrosine; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src)