Growth inhibition of human hepatoma cells (HepG2) by polyunsaturated fatty acids. Protection by albumin and vitamin E.

Albumin carries fatty acids and has also been suggested to act as an antioxidant. In the present work, polyunsaturated fatty acids (linoleic, arachidonic, eicosapentaenoic and docosahexaenoic acids)--but not palmitic and oleic acid--inhibited growth of human hepatoma cells in low albumin concentration (0.5%). Growth inhibition by polyunsaturated fatty acids was prevented by albumin in a dose-related manner in the range 0.7-5.0%. Albumin also protected against growth inhibition following catabolism (by lipoprotein lipase) of very low density lipoproteins. Vitamin E strongly counteracted the inhibitory effect of polyunsaturated fatty acids. Vitamin E and albumin appeared to have additive effects in protecting against growth inhibition by polyunsaturated fatty acids. Indomethacin did not greatly modify the polyunsaturated fatty acids effect. Growth inhibition by polyunsaturated fatty acids, as well as the level of thiobarbituric acid reacting substances (a measure of lipid peroxidation) in growth media, increased with increasing number of fatty acids double bonds. Vitamin E and albumin prevented both thiobarbituric acid reacting substances formation and growth inhibition by polyunsaturated fatty acids. The results suggest that the concentrations of albumin and vitamin E in the incubation medium are essential when studying polyunsaturated fatty acids effects on cell growth.