Accumulation of N-3 Polyunsaturated Fatty Acids by Cultured Human Y79 Retinoblastoma Cells

Abstract: The metabolism of the n-3 class of polyunsaturated fatty acids, which occur in relatively high quantities in neural tissues, was studied in human Y79 retinoblastoma cells. These cells contained low levels of n-3 polyunsaturates when grown in culture media supplemented with fetal bovine serum. The cells readily incorporated preformed docosahexaenoic acid (22:6 n-3) into phospholipids, but human skin fibroblasts did this to a similar extent. When 10 to 30 μmol/ml linolenic acid (18:3 n-3) was added, the cells also accumulated 22:6 in phospholipids. The capacity to convert appreciable amounts of 18:3 to 22:6 appears to be a unique property of the retinoblastoma cells as compared with other continuously cultured cell lines. More 18:3 than linoleic acid (18:2 n-6) was incorporated into phospholipids by the retinoblastoma cultures, and 18:3 was channeled to a larger extent into the ethanolamine glycerophospholipid fraction. These findings indicate that retinoblastoma cells handle n-3 polyunsaturated fatty acids in a manner very similar to neural tissue in vivo . Based on the results obtained with this model system, it appears that three processes may contribute to the accumulation of 22:6 in retina and neural tissue: increased ability to incorporate 18:3, the capacity to convert 18:3 to 22:6, and channeling of 18:3 and its metabolites into ethanolamine glycerophospholipids.