Inhibitory effect of gramicidin S on the growth of murine tumor cells in vitro and in vivo.

The Effect of gramicidin S (GS), a polypeptide antibiotic, on the growth of murine tumor cells such as allotransplantable sarcoma 180 (S180) and Ehrlich ascites carcinoma (EAC) and Meth A fibrosarcoma (Meth A) was studied. GS inhibited the proliferation of EAC cells in culture and its effect on cell viability was dependent on the concentration of GS. On exposure to GS at concentrations ranging from 1 to 100 micrograms/ml for 10 min, EAC cells lost their transplantability in ddY mice depending on the concentration of GS. In particular, the transplantability of EAC cells was completely missing on exposure to GS at a concentration of 100 micrograms/ml. In the in vivo experiments, a daily intraperitoneal injection of GS exhibited a high inhibitory effect not only on the growth of subcutaneously implanted S180 in ICR mice but on the growth of subcutaneously implanted syngeneic Meth A in BALB/c mice. In the studies using radioactively labeled DNA, RNA and protein precursors, GS at high concentrations inhibited the incorporation of all the precursors into EAC cells.