Metabolism of n-9, n-6 and n-3 fatty acids in hepatoma Morris 7777 cells. Preferential accumulation of linoleic acid in cardiolipin

The objective of this study was to investigate, using a pulse-chase techniq ue, the different incorporation of (1-C-14) n-9, n-6 and n-3 fatty acids in to hepatoma lipids and their secretion to the culture medium. Docosahexaeno ic acid (DHA) accumulated preferentially into the triacylglycerol while ara chidonic acid (AA) did into the phospholipid fraction. DHA was poorly secre ted to the culture medium whereas AA was secreted to a large extent. The fa tty acids were initially esterified mainly into phophatidylcholine and phos phatidylethanolamine. During the 24 h chase, a general shift from phophatid ylcholine to phosphatidylethanolamine was observed. Linoleic acid was ester ified in cardiolipin to a much greater extent than any other fatty acid and it was not converted to more polyunsaturated fatty acids. The supplementation of the culture medium with polyunsaturated fatty acids had no inhibitory effect on the growth of the hepatoma cells, in marked con trast to observations made in other tumoral cells. The reasons for the resi stance of the hepatoma cells to polyunsaturated fatty acid toxicity, includ ing the possible antioxidant effect of linoleic acid accumulation in cardio lipin, are also discussed. (C) 2000 Harcourt Publishers Ltd.