INCORPORATION OF 12(S)-HYDROXYEICOSATETRAENOIC ACID INTO PHOSPHOLIPIDS AND ACTIVE DIACYLGLYCEROLS IN RAT-LIVER EPITHELIAL-CELLS - EFFECTS ON DNA-SYNTHESIS

12(S)-Hydroxyeicosatetraenoic acid (12-HETE), the 12-lipoxygenase-deri ved metabolite of arachidonic acid, was incorporated into membrane pho spholipids (PL) in various cells. PL are precursors of diacylglycerol (DAG), a protein kinase C (PKC) activator involved in cell-growth sign aling. We studied 12-HETE incorporation into PL in non-transformed (NT -) and spontaneously transformed (T-) rat liver epithelial cells (RLEC ), and its consequence on DNA synthesis. NT- and T-RLEC incorporated 1 2-HETE predominantly into phosphatidylcholine (PC). 12-HETE was incorp orated at a greater rate, and with a higher phosphatidylethanolamine ( PE)/PC ratio in T-cells. Preincubation of RLEC with 12-HETE at greater than or equal to 0.5 mu M partially inhibited basal DNA synthesis in NT- and T-RLEC, Preincubation of NT-RLEC with 12-HETE (2.5 mu M) also decreased bradykinin-stimulated DNA synthesis. Unstimulated RLEC produ ced 1-acyl-2-(12-HETE)DAG which was increased in NT-RLEC by bradykinin stimulation. Finally, 1-stearoyl-2-(12-HETE)DAG was as potent an in v itro PKC activator as 1-stearoyl-2-arachidonyl-DAG. These data demonst rate that 12-HETE incorporation into PL resulted in the production of active 12-HETE-containing DAG, together with reduced DNA synthesis.