Effects of tumor necrosis factor and interferon-beta on proliferation and epidermal growth factor binding in young...

Tumor necrosis factor-alpha (TNF) and various interferons (IFN) have potent cytostatic or cytotoxic effects on a variety of human tumor-derived cell lines. Their effects on normal cells are more controversial. We have examined the effects of TNF and IFN-beta on the proliferation of WI-38 cells in a serum-free, growth factor-supplemented medium and in serum-containing medium. These cells respond to the combination of epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), and dexamethasone by DNA synthesis at a rate and extent equivalent to serum-stimulated cells. TNF has no effect on this growth factor-stimulated proliferation. However, it is stimulatory in serum-containing medium. IFN-beta inhibits DNA synthesis 60 to 70% in both young and senescent cells. TNF and IFN-beta together have a synergistic effect and completely inhibit growth factor-stimulated DNA synthesis in young cells. No synergism was observed with senescent cells. TNF stimulated an increase in the number of EGF specific binding sites two- to threefold in 24 h in both young and senescent cells. This seems to result from a proportional increase in a very high affinity binding site. IFN-beta has little or no effect on EGF binding either alone or in combination with TNF.