Response of L-1210 Tumor in Mice Toward Treatment with Interferon or Poly(I) • Poly(C)

Abstract

Two interferon (IFN)-mediated enzyme activities, the protein kinase and pppA(2′p5′A)_n synthetase (2-5A synthetase) were employed to demonstrate the action of IFN on different tissues of mice as well as in ascitic tumors of L-1210 IFN (α + β)-sensitive (L-1210S) and IFN-resistant (L-1210R) leukemia cells. The protein kinase is manifested by the phosphorylation of endogenous protein of molecular weight 67 kD) (p67K kinase). Control and L-1210R or L-1210S tumor-bearing mice were found to respond similarly to treatment with IFN or when injected with an IFN inducer, poly(I). poly(C). The 2-5A synthetase and the p67K kinase were enhanced in the lung and the spleen of mice, both control and with tumor graft. There was no apparent effect on L-1210R leukemia cells whereas in L-1210S cells the level of both enzymes was enhanced in response to treatment of mice with IFN or poly(I). poly(C). These results indicate that the presence of tumor cells did not trigger modifications in the response of mice toward treatment with IFN. Furthermore, they provide biochemical evidences to show the response of IFN-sensitive and IFNresistant tumor cells during treatment of the host with IFN.