Antiproliferative activity of recombinant interferons alpha and beta for human renal carcinoma cells: Supra-additive activity with elevated temperature or vinblastine

Abstract

We are investigating IFN activity for human renal cell carcinoma (RCC) in conjunction with other forms of therapy in vitro. Our investigations employed IFN alpha and beta generated by recombinant DNA technology. We employed IFN species in conjunction with vinblastine or elevated temperature of incubation for RCC cells. Recombinant IFNs alpha and beta were provided by Triton/Cetus IFN program. RCC cells grown at 37°C with 1,000 IU/ml IFN alpha for seven days produced significant inhibition in growth kinetics (p<0.01). Incubation at 39.5 °C significantly augmented inhibition producing cytotoxicity without altering growth kinetics in controls (p<0.01). Treatment of cells with IFN beta (5 ng/ml) 24 hours prior to treatment with vinblastine (0.25 μg/ml×1 h) resulted in supra-additive inhibition of growth kinetics as determined by isobole analysis (p<0.001). Concomitant treatment with IFN and vinblastine or IFN treatment 24 hours after vinblastine treatment augmented inhibition to a lesser extent. Our results suggest supra-additive biological activity of recombinant IFN at increased temperature, or with vinblastine.