TRANSFECTION OF C3H10T1 2 CELLS WITH THE HARVEY-RAS ONCOGENE REDUCES CYTOSOLIC PHOSPHOLIPASE A(2) FUNCTION/

Several lines of evidence suggest that phospholipase A(2) may play a r ole in the activated ras-mediated transformation process. In the prese nt study, phospholipase A(2) activity and expression were assessed in a murine fibroblast cell line (C3H10T1/2 cells) that was stably transf ected with the Harvey ras oncogene, a cellular model used for studying multistage carcinogenesis. Reduced levels of fatty acids were release d from the ras-transfected cells compared to untransfected controls. T he in vitro phospholipase A(2) activity apparent in the C3H10T1/2 show ed preference for sn-2 arachidonyl phosphatidylcholine compared to dip almitoyl phosphatidylcholine. The activity, as well as the cytosolic p hospholipase A(2) immunoreactive protein, was reduced by 50% in the ra s-transfected cells compared to control cells. These results suggest t hat the cytosolic phospholipase A(2) is the predominant form of this e nzyme family expressed in C3H10T1/2 cells and that the activity and pr otein amount is reduced by 50% in these cells when stably transfected with the Harvey ras oncogene.