title: Resistance to the antiproliferative activity of IFN-alpha: further characterization and demonstration of antagonistic effects of IFN-gamma.
abstract: Mouse B16 melanoma cells have been shown to rapidly develop resistance to the antiproliferative effects of MuIFN-alpha or MuIFN-beta when exposed to these interferons. In cloning studies, the maximal antiproliferative effects of MuIFN-alpha were seen with 2-4 days treatment. This resistance has been further characterized. The level of resistance which develops in B16 melanoma cells is dependent upon the concentration of MuIFN-alpha to which the cells are exposed. In addition, B16 melanoma cells which are resistant to the antiproliferative effects of MuIFN-alpha have greatly elevated levels of the interferon-induced enzyme 2',5'-oligoadenylate (2-5A) synthetase. Since it has previously been shown that B16 melanoma cells do not develop resistance to the antiproliferative effects of MuIFN-gamma, several experiments studied the influence of MuIFN-gamma on the development of resistance to MuIFN-alpha. Combinations of IFN-gamma and IFN-alpha have previously been shown to result in a synergistic enhancement of the antiproliferative effects. Kinetic studies show that the response of the cells to the MuIFN-gamma antiproliferative effect appears to be dominant over the development of resistance since no resistance develops in response to combination treatment. Not only is MuIFN-gamma able to prevent development of resistance when it is present continuously, but also when it is used for the sequential treatment of the cells before their exposure to MuIFN-alpha. A 2-day pretreatment with MuIFN-gamma is sufficient to prevent the development of resistance during later exposure of the cells to MuIFN-alpha alone for up to 6 additional days.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Microbiology, University of Texas Medical Branch, Galveston.
authors.forename: C M
authors.initials: CM
authors.lastname: Fleischmann
authors.forename: W R
authors.initials: WR
authors.lastname: Fleischmann
mesh_terms: D015088:2',5'-Oligoadenylate Synthetase / Q000096:biosynthesis; D000818:Animals; D002455:Cell Division; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance / Q000502:physiology*; D007370:Interferon Type I / Q000037:antagonists & inhibitors / Q000494:pharmacology; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008546:Melanoma, Experimental / Q000201:enzymology; D051379:Mice; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D007370:Interferon Type I; D007371:Interferon-gamma; D015088:2',5'-Oligoadenylate Synthetase