title: Time-dependent differential effects of natural and recombinant murine interferon-gamma on ornithine decarboxylase activity of tumor cells.
abstract: Incubation of quiescent tumor cells with fetal calf serum induced ornithine decarboxylase (ODCase) activity concomitantly with mitogenic stimulation. Pretreatment of cells with highly purified natural or recombinant murine interferon-gamma (MuIFN-gamma) for 5 h caused a dose-dependent increase of ODCase activity induced by fetal calf serum (FCS). Pretreatment of target cells with IFN-gamma for 5 h in absence of FCS stimulation did not induce ODCase activity. When pretreatment of cells with natural or recombinant MuIFN-gamma was prolonged for 18 h both ODCase activity and DNA synthesis induced by FCS were suppressed. By contrast when a mixture of MuIFN-alpha and -beta was used, ODCase activity was significantly suppressed after 5 h pretreatment compared to untreated controls. These results suggest that IFN-gamma exerts a differential effect on mitogen-stimulated events depending on the dose and the time of addition.
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D007370:Interferon Type I / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D051379:Mice; D009374:Neoplasms, Experimental / Q000473:pathology / Q000503:physiopathology*; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D007370:Interferon Type I; D011994:Recombinant Proteins; D007371:Interferon-gamma; D004247:DNA; D009955:Ornithine Decarboxylase