Effect of Insulin on Free Tumor Cells in Peritoneal Exudate and on Their Host. ∗

Abstract

Summary and Conclusions

CFW mice were inoculated i.p. with S-180 or S-37 cell suspensions and treated with 3 daily i.m. injections of globin insulin (0.5 to 2 units). On the 4th or 5th day, specimens of peritoneal exudate were withdrawn from these mice and from untreated controls; the number of tumor cells per cmm and the percentage of their mitoses were consistently lower in insulin treated animals; this effect of insulin could be prevented by repeated injections of glucose (1 cc of 20% solution). In other experiments, the survival span was recorded for insulin treated tumor-bearing animals, their untreated controls and insulin treated normal mice. The first group showed the shortest survival which could not be extended by injections of glucose. It is concluded that growth of free tumor cells in the exudate was reversibly inhibited by hypoglycemia, its metabolic products or by the direct effect of insulin on tumor cells (permeability?) and that the same factors (or some of them) provided additional stress to some vitally important tissues damaged by tumor growth.