Effects of gamma-linolenic acid on murine cells in vitro and in vivo.

The effects of gamma-linolenic acid (GLA) on growth of cells of the continuous murine sarcoma line M52B were investigated in vitro. Prostaglandin (PG) production by these cells after GLA treatment was also measured. GLA inhibited the growth of M52B cells and became overtly toxic at high doses or after long periods of exposure to lower doses. The inhibitory effects of GLA were accompanied by an increase in PGE production by M52B cells. However, the rise in PGE was not statistically significant. Accordingly the extent to which PGE may contribute to the inhibition observed with GLA remains unclear. In order to establish whether these in vitro effects could be reproduced in vivo, athymic nude mice bearing murine sarcoma allografts were fed either standard laboratory diets or diets supplemented with 35% evening primrose oil, which contains 10% GLA. As there was no significant difference in tumour volumes between the two groups at the end of the treatment period, the oil-enriched diet was concluded to be without effect on tumour growth in this in vivo model.