The lack of PDGE-stimulated PGE2 release from ras-transformed NIH-3T3 cells results from reduced phospholipase C but not phospholipase A2 activity.
Our previous work demonstrated that NIH-3T3 cells expressing high levels of the mutated cellular ras oncogene (EJ-ras gene) exhibited reduced hormone-sensitive adenylate cyclase and platelet-derived growth factor-stimulated (PDGF) phospholipase A2/C activities. We now report that although the ras-transformed cells display markedly reduced phospholipase C activity, as measured by the levels of inositol 1,4,5-trisphosphate synthesized after PDGF-stimulation, normal levels of phospholipase A2 activity can be uncovered; thus, similar levels of prostaglandin E2 were synthesized in EJ-ras transformed and control cells after stimulation with phorbol myristate acetate (PMA) and/or the calcium ionophore A-23187, agents which stimulate protein kinase C and intracellular Ca2+ levels, respectively. These data suggest that the EJ-ras gene product uncouples the PDGF receptor from the phospholipase C, resulting in reduced PDGF-stimulated Ca2+ mobilization, protein kinase C stimulation and an apparent decrease in Ca2+-dependent phospholipase A2.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D015232:Dinoprostone; D007700:Kinetics; D051379:Mice; D008815:Mice, Inbred Strains; D009857:Oncogenes; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011458:Prostaglandins E / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism*
D010982:Platelet-Derived Growth Factor; D011458:Prostaglandins E; D000001:Calcimycin; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate