GAMMA-LINOLENIC ACID SUPPLEMENTATION CAN AFFECT CANCER CELL-PROLIFERATION VIA MODIFICATION OF FATTY-ACID COMPOSITION

We examined the effect of gamma-linolenic acid (GLA) supplementation o n the growth and fatty acid composition of three human tumor cell line s (the neuroblastoma CHP-212, the tubal carcinoma TG, and the colon ca rcinoma SW-620), in order to evaluate the relationship between GLA-ind uced tumor cell death and the distribution of fatty acids in tumor cel ls. At the highest GLA concentrations (10 and 20 mu g/ml), the DNA syn thesis was completely abolished; at 5 mu g/ml GLA only SW-620 cells di d not proliferate, while CHP-212 and TG cells showed a residual [H-3]- thymidine incorporation. GLA levels were very low in cells grown in co ntrol medium; GLA supplementation caused a significant incorporation o f GLA itself in all the cell lines at each concentration. In TG and CH P-212 cells, GLA was metabolized, although to a different extent, to d ihomo-gamma linolenic acid and arachidonic acid. SW-620 cells neither elongated nor desaturated the incorporated GLA. The highest cytostatic effect was reached when GLA was not transformed into its metabolites, suggesting that the GLA toxicity to tumor cells is not dependent on m etabolites but is due to GLA itself. (C) 1996 Academic Press, Inc.