METABOLISM OF RADIOLABELED 18 2N-6 AND 18/3N-6 BY NIH-3T3 CELLS AND THE DT SUBCLONE/

The incorporation and metabolism of delta-6-desaturase substrate and p roduct, [1-C-14]-linoleic (18:2n-6) and [1-C-14]-gamma-linolenic acid (18.3n-6), was examined in NIH-3T3 cells and the DT subclone which dif fers only in the presence of the v-Ki-ras oncogene. Similar amounts of post delta-6 and delta-5 desaturase metabolites were found in both ce ll lines indicating that the activity of these important enzymes of fa tty acid metabolism was not affected by the expression of the oncogene . However, measurable quantities of the direct elongation product of 1 8:2n-6, 20:2n-6, were only found in DT cells. Radiolabel was recovered predominantly from the phospholipid fraction at low fatty acid concen trations, whereas neutral lipid labelling occurred when higher concent rations of exogenous fatty acid were present. This effect was most pro nounced in DT cells and may result from the presence of the activated ras ongogene.