Usefulness of Glycosylated Recombinant Human Lymphotoxin for Growth Inhibition of Human and Murine Solid Tumors and Experimental Metastasis in Mice

Abstract

We have examined the antitumor and antimetastatic effects of native-type, glycosylated recombinant lymphotoxin (LT) on human and murine tumors transplanted in mice. The results reported here are as follows: (a) The in vivo antitumor spectrum of LT is not coincident with the in vitro study, and it has a wide antitumor spectrum and substantially inhibits the growth of human solid tumors, (b) When both syngeneic and nude mice are transplanted with Meth A tumor, the significant growth-inhibitory effect of LT is obtained in syngeneic mice, but the effect is quite small in nude mice regardless of the routes; LT attains the same degree of effectiveness as that in syngeneic mice, but at an 8 to 16 times higher dose. Furthermore, the pretreatment with anti-asialo-GM1 antibody inhibits the antitumor effects of LT in syngeneic mice, (c) In the pulmonary metastasis model induced by i.v. injection of Meth A cells, a high preventive effect of LT is obtained by systemic administration in syngeneic mice, but not in nude mice. In addition, the pretreatment with anti-asialo-GM1 antibody completely prevents the antimetastatic effect of LT, but also blocks that effect of control mice without LT treatment. In conclusion, LT appears to be a potent cytokine against tumor growth and metastasis in vivo. The differences between nude and syngeneic mice suggest the involvement of host immunity in the expression of LT function.