Effect of lysolecithin and analogs on mouse ascites tumors.

Antitumor activity of lysolecithin and its ester and ether analogs has been investigated in three mouse ascites tumors: Meth A, Ehrlich, and Sarcoma S180J. Immediately after mice were inoculated i.p. with a suspension of tumor cells, they were given a single i.p. injection of lysolecithin or an analog. Inhibition of tumor growth was measured as the total packed cell volume on Day 8. Lysolecithin induced tumor inhibition against Ehrlich and S180J and, to a lesser extent, against Meth A ascites tumor. Further tests with ester-deoxylysolecithin analogs against Meth A showed that derivatives with stearic or lauric acid esters on the C-1 atom of the propanediol moiety induced tumor inhibition to a variable degree. However, the ether analogs, 1-hexadecyl or 1-dodecylpropanediol-3-phosphorylcholines and ot-1,2-dioctylglycero3-phosphorylcholine, but not the 1-decylpropanediol-3phosphorycholine, produced more marked, reproducible inhibition. Detergents, sodium dodecyl sulfate and Hyamine 10-X hydroxide, when injected i.p. immediately after ascites cells, reduced the capacity of the tumor cells to multiply as indicated by lower total packed cell volume on Day 8. Tween 80 did not produce this effect at the same dose. The effect of lysolecithin against the Meth A ascites was observed when treatment was administered 4 days before tumor inoculation but not before that day or subsequently. 1-Hexadecylpropanediol-3-phosphorylcholine was effec tive when administered as early as 7 days before tumor inoculation or as late as 2 days after. Treatment with lysolecithin of mice inoculated with 0.5 to 2 x 10°Meth A calls significantly prolonged the median survival time of tumor hosts. Exposure of ascites cells of Meth A tumor to lysoleci thin, 1-hexadecylpropanediol-3-phosphorylcholine, or Hy amine 10-X hydroxide destroyed the cells as shown by trypan blue staining and by reduction of the capacity of the cells to produce tumors on intradermal injection into mice. The concentrations of these substances required to produce a 50% effect were similar over a narrow range. Far higher concentrations of sodium dodecyl sulfate were required for a comparable effect.