Combined effects of polyunsaturated fatty acids on formation of perox1dation products by liver and breast cancer cells

In earlier work we and others have found that the tram (TLA) and conjugated (CLA) isomers of linoleic acid can inhibit the proliferation of some cancer cell lines. There have been conflicting reports on the anti-oxidative properties of CLA while TLA has been found to influence the metabolism of cis unsaturated fatty acids. We have examined the combined effects of TLA and CLA on the conversion of linolenic acids to oxidation products as judged by formation of thiobarbiturate-reactive substances (TEARS). The formation of peroxidation products by hepatoma cells was in the order: gamma-linolenic acid>alpha-h'nolenic acid>CLA>TLA. The production of TEARS from alpha-linolenic by rat hepatoma cells was significantly decreased by TLA with 200 (iM concentrations but not at 100 uM. Combined incubation of CLA with alpha-linolenic usually gave close to additive effects with hepatoma and breast cancer cells although with 7800NJ rat hepatoma cells there was a less than additive effect with 200 \iM alpha-linolenic acid and 50 uM CLA. In conclusion, combined addition of linolenic acids with conjugated linoleic acid or linolelaidic acid gave metabolite yields that were frequently non-additive and suggested that the toxic effects of linolenic acids on cancer cells may be influenced by the presence of other fatty acids.