Identification of constitutive and γ-interferon- and interleukin 4-regulated proteins in the human renal carcinoma cell line ACHN

The effects of IFN-gamma and interleukin 4 (IL-4) on cell proliferation and two-dimensional gel electrophoretic protein patterns of the human renal carcinoma cell line ACHN were studied. Treatment of the cells with IFN-gamma resulted in a 40-50% decrease in their proliferation. IL-4 treatment resulted in a 30-40% decrease. Treating cells with both cytokines had the same effect as with IFN-gamma alone, thus precluding a synergistic antiproliferative interaction of these two cytokines. To identify IL-4- and IFN-gamma-regulated proteins in ACHN, two-dimensional preparative gel electrophoresis was used, combined with either capillary electrophoresis or high-performance liquid chromatography and either Edman or mass spectrometric sequencing. The following cytokine-induced proteins were identified: tropomyosin, heat shock protein 27, manganese superoxide dismutase, glutathione S-transferase pi, and protein kinase C inhibitor I. Tropomyosin increased 2-fold when cells were treated with IFN-gamma. Levels of heat shock protein 27 increased 2-fold with IL-4, 3-fold with IFN-gamma, and 4-fold when the cytokines were used in combination. Manganese superoxide dismutase increased 3-fold with IFN-gamma but was unaffected by IL-4. Glutathione S-transferase pi increased 3-fold with IFN-gamma. Levels of protein kinase C inhibitor I increased greater than 3-fold with IL-4, 4-fold with IFN-gamma, and 7-fold when both cytokines were used. In addition, the following constitutive ACHN proteins were identified: copper zinc superoxide dismutase, 60S acidic ribosomal protein P2, and a second heat shock protein 27 isoform. These findings help define the biochemical modes of action of IFN-gamma and IL-4 and their potential in the biological therapy of renal cell carcinoma.