Interferon-specific effects on protein synthesis in P3HR-1 cells.

The effect of interferon (IFN) on protein synthesis was studied in the Burkitt's lymphoma cell line P3HR-1 by [35S]methionine labelling of the cells, followed by two-dimensional gel electrophoresis of cell extracts. De novo synthesis of three proteins (mol. wts. 33 000, 62 000, and 98 000, respectively) and alterations in the rate of synthesis for a small number of additional proteins were observed during the first 12 h of treatment, while the rate of overall protein synthesis was unaffected. Treatment of P3HR-1 cells with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or hydrocortisone (HC), which induce similar changes in cell cycle distribution as does IFN, did not induce comparable changes in the rates of protein synthesis. Thus, the effects were specific for IFN and not induced by the change in cell cycle distribution per se, i.e., accumulation in G0. Treatment of cells with 2'-5' pA core did not mimic the effect of IFN at the translational level. A substrain of P3HR-1 cells, selected for resistance to the anti-proliferative effect of IFN, lacked six proteins found in the wild-type. The 62 000 mol. wt. protein was induced in this substrain as well as in native P3HR-1 cells on addition of IFN. The resistant substrain still developed an anti-viral effect in response to IFN. Thus, it seems as if the anti-proliferative and anti-viral effects of IFN, at least in some cells are mediated by different intracellular molecular mechanisms.