EFFECT OF SUCROSE MONOSTEARATE, AN EMULSIFIER, ON POLYAMINE METABOLISM AND PHOSPHATIDYLINOSITOL TURNOVER IN EHRLICH ASCITES TUMOR-CELLS

Sucrose esters of fatty acids have antitumor activity. We studied the effect of sucrose monostearate (SS), an emulsifier, on polyamine metab olism and phosphatidylinositol turnover in Ehrlich ascites tumor cells . The activity of ornithine decarboxylase (ODC) was increased in the c ells by changing the medium. This increase in the activity was inhibit ed by adding sucrose stearate, but not sucrose or stearate to the medi um. The activity of spermidine/spermine N-1-acetyltransferase (SAT), a rate-limiting enzyme of polyamine biodegradation, was enhanced with t he addition of SS in a time- and dose-dependent manner. The elevation of SAT activity was completely prevented when cycloheximide was added to the culture simultaneously. In in vitro studies, SS at various conc entrations up to 1 mM hardly affected the activities of ODC or SAT. Th e incorporation of [H-3]inositol into both fractions of inositolphosph olipid and inositol phosphates was inhibited by SS. These results sugg est that the perturbation of polyamine metabolism and phosphatidylinos itol turnover is involved in the mechanism of antitumor activity of SS in Ehrlich ascites tumor cells.