DIVERSE EFFECTS OF ESSENTIAL (N-6 AND N-3) FATTY-ACIDS ON CULTURED-CELLS

Fatty acids (FAs) have long been recognized for their nutritional valu e in the absence of glucose, and as necessary components of cell membr anes. However, FAs have other effects on cells that may be less famili ar. Polyunsaturated FAs of dietary origin (n-6 and n-3) cannot be synt hesized by mammals, and are termed 'essential' because they are requir ed for the optimal biologic function of specialized cells and tissues. However, they do not appear to be necessary for normal growth and met abolism of a variety of cells in culture. The essential fatty acids (E FAs) have received increased attention in recent years due to their pr esumed involvement in cardiovascular disorders and in cancers of the b reast, pancreas, colon and prostate. Many in vitro systems have emerge d which either examine the role of EFAs in human disease directly, or utilize EFAs to mimic the in vivo cellular environment. The effects of EFAs on cells are both direct and indirect. As components of membrane phospholipids, and due to their varying structural and physical prope rties, EFAs can alter membrane fluidity, at least in the local environ ment, and affect any process that is mediated via the membrane. EFAs c ontaining 20 carbons and at least three double bonds can be enzymatica lly converted to eicosanoid hormones, which play important roles in a variety of physiological and pathological processes. Alternatively, EF As released into cells from phospholipids can act as second messengers that activate protein kinase C. Furthermore, susceptibility to oxidat ive damage increases with the degree of unsaturation, a complication t hat merits consideration because lipid peroxidation can lead to a vari ety of substances with toxic and mutagenic properties. The effects of EFAs on cultured cells are illustrated using the responses of normal a nd tumor human mammary epithelial cells. A thorough evaluation of EFA effects on commercially important cells could be used to advantage in the biotechnology industry by identifying EFA supplements that lead to improved cell growth and/or productivity.