PHOSPHOLIPASES A(2) IN RAS-TRANSFECTED FIBROBLASTS

Phospholipase A(2) (PLA(2)) generated lipid biomediators cart facilita te neoplastic progression. Specific PLA(2) alterations associated with ms oncogene expression were determined by comparison of PLA(2) activi ties in nontumorigenic rat embryo fibroblasts (CREF cells) and their t umorigenic ras oncogene-transfected counterparts (CREF-T24 cells). The high molecular mass cytosolic PLA(2) activity is 2-3 fold higher in C REF-T24 cells as compared to CREF cells. Western blotting analyses ind icate inn eases in the level of this enzyme and the proportion which m igrates with phosphorylated enzyme in CREF-T24 cells. A PLA(2) activit y, with the characteristics of a group II PLA(2), is readily detectibl e in particulate fractions from CREF-T24 cells following ammonium sulf ate extraction/cation ion exchange chromatography. In contrast, this a ctivity is minimal in similarly prepared CREF cell samples. While the CREF-T24 cells have increases in Two PLA2 activities associated with t he release of arachidonic acid the CREF-T24 and CREF cells are similar with respect to Ca2+ independent, particulate fraction-associated PLA 2 activities.