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Fisher, P. B., H. Hermo, Jr., W. E. Solowey, M. C. Dietrich, G. M. Edwalds, I. B. Weinstein, J. A. Langer, S. Pestka, P. Giacomini, M. Kusama, and et al. 1986. Effect of recombinant human fibroblast interferon and mezerein on growth, differentiation, immune interferon binding and tumor associated antigen expression in human melanoma cells. Anticancer Res 6: 765-74.

The combination of recombinant human fibroblast interferon (INF-delta) and the antileukemic compound mezerein (MEZ) results in a synergistic suppression in the growth of human melanoma cells and a concomitant increase in melanin synthesis. In the present study we have further analyzed this synergistic interaction and have also evaluated the effect of IFN-delta and MEZ, alone and in combination, on recombinant human gamma interferon (IFN-gamma) binding and Class I HLA and melanoma associated antigen (MAA) expression in the HO-1 human melanoma cell line. Single cell clones isolated from the HO-1 cell line varied in their sensitivity to the antiproliferative effects of IFN-delta and MEZ. With all twelve clones, however, the combination of IFN-delta plus MEZ was more growth inhibitory than either agent used alone, even in HO-1 subclones displaying relative resistance to IFN-delta. By continuous growth in gradually increasing concentrations of IFN-delta, a variant population of HO-1 cells, HO-1 delta R-D, was generated which was more resistant to the antigrowth effects of IFN-delta than the original HO-1 parental cell line. In the IFN delta R-D cell line the combination of IFN-delta plus MEZ synergistically suppressed growth. Exposure of HO-1 cells to 2500 units/ml IFN-delta or 50 ng/ml MEZ for 96 hr resulted in no change or an increase in the binding of labelled IFN-gamma to surface receptors, whereas the combination of IFN-delta plus MEZ increased IFN-gamma binding 2-to-4-fold in HO-1 cells. This increase was the result of an increase in the number of receptors on treated cells coupled with a protection against a decrease in receptors observed for confluent untreated cells. Changes in IFN-gamma binding resulting from treatment with IFN-delta plus MEZ were not associated with alterations in the binding affinity of INF-gamma to its receptor. Changes were also observed in the expression of HLA Class I antigens and MAAs following treatment of HO-1 cells with IFN-delta, MEZ or IFN-delta plus MEZ. IFN-delta and MEZ increased the expression of HLA Class I antigens a 96 kd MAA defined by MoAb CL203, a 100 kd MAA defined by MoAb 376.96 and a 115 kd MAA defined by MoAb 345.134 but decreased the expression of a high molecular weight-melanoma associated antigen (HMW-MAA) defined by MoAb 325.28S. abstract truncated at 400 words

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