| Abstract: | The administration of interferon-alpha/beta to female nude (nu/nu) mice caused significant changes in the levels of the cytosolic hepatic glutathione transferases. Antibodies raised against rat subunits, Ya, Yc, Yb1, Yb2, and Yk, and the subunits of the human transferases, mu (YbYb), lambda (YfYf), and epsilon (B1B1) all reacted with enzymes in the mouse and were used to demonstrate suppression and induction of transferase levels. Western blot analysis followed by semiquantitation by laser scanning showed the Ya, Yb1, Yb2, Yc, Yk, mu, and B1 subunits to be suppressed by 11, 11, 44, 30, 12, 14, and 47%, respectively, by interferon treatment. In contrast to these findings, the Yf subunit was induced 5-7-fold. A concomitant 220% increase was observed in the specific activity of the hepatic cytosol for ethacrynic acid, a substrate for the Yf subunit. Changes in the levels of transferase enzymes in normal and tumor cells may have significant implications when cytotoxic drugs are used in combination with interferons in cancer therapy. The Yf subunit, an enzyme found in human tumors and in placenta (Polidoro, G., Di Mio, C., Del Boccio, G., Zulli, P., and Fererici, G. (1980) Biochem. Pharmacol. 29, 1677-1680) has also been shown to be elevated in hepatic preneoplastic lesions (Kitahara, A., Satoh, K., Nishimura, K., Ishikawa, T., Ruike, K., Sato, K., Tsuda, H., and Ito, N. (1984) Cancer Res. 44, 2698-2703). These data indicate that the Yf subunit represents a potentially important interferon-inducible gene product. |
