Phospholipases A2 in ras-transfected fibroblasts.

Phospholipase A2 (PLA2) generated lipid biomediators can facilitate neoplastic progression. Specific PLA2 alterations associated with ras oncogene expression were determined by comparison of PLA2 activities in nontumorigenic rat embryo fibroblasts (CREF cells) and their tumorigenic ras oncogene-transfected counterparts (CREF-T24 cells). The high molecular mass cytosolic PLA2 activity is 2-3 fold higher in CREF-T24 cells as compared to CREF cells. Western blotting analyses indicate increases in the level of this enzyme and the proportion which migrates with phosphorylated enzyme in CREF-T24 cells. A PLA2 activity, with the characteristics of a group II PLA2, is readily detectible in particulate fractions from CREF-T24 cells following ammonium sulfate extraction/cation ion exchange chromatography. In contrast, this activity is minimal in similarly prepared CREF cell samples. While the CREF-T24 cells have increases in two PLA2 activities associated with the release of arachidonic acid, the CREF-T24 and CREF cells are similar with respect to Ca2+ independent, particulate fraction-associated PLA2 activities.