Loss of platelet-derived growth factor-stimulated phospholipase activity in NIH-3T3 cells expressing the EJ-ras oncogene.
- 1 January 1987
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 84 (2), 546-550
- https://doi.org/10.1073/pnas.84.2.546
Abstract
Data indicating that the 21-kDa protein (p21) Harvey-ras gene product shares sequence homology with guanine nucleotide-binding proteins (G proteins) has stimulated research on the influence(s) of p21 on G-protein-regulated systems in vertebrate cells. Our previous work demonstrated that NIH-3T3 mouse cells expressing high levels of the cellular ras oncogene isolated from the EJ human bladder carcinoma (EJ-ras) exhibited reduced hormone-stimulated adenylate cyclase activity. We now report that in these cells another enzyme system thought to be regulated by G proteins is inhibited, namely phospholipases A2 and C. NIH-3T3 cells incubated in plasma-derived serum release significant levels of prostaglandin E2 (PGE2) as determined by radioimmunoassay when exposed to platelet-derived growth factor (PDGF) at 2 units/ml; the levels of PGE2 released from EJ-ras-transfected cells are only 3% those of controls despite a similar basal (unstimulated) release from control and EJ-ras-transfected cells. The lack of PDGF-stimulated PGE2 release from EJ-ras-transfected cells is not due to a defect in the prostaglandin cyclooxygenase enzyme, since incubation of control cells and EJ-ras-transfected cells in 0.33, 3.3, or 33 .mu.M arachidonate resulted in identical levels of PGE2 release. The lack of PDGF-stimulated PGE2 release from EJ-ras-transfected cells also does not result from the loss of functional PDGF receptors. EJ-ras-transformed cells bind 70% as much 125I-labeled PDGF as control cells and are stimulated to incorporate [3H]thymidine and to proliferate after exposure to PDGF. Moreover, this inhibition is not likely the result of a secondary cellular effect related to the transformed phenotype, since NIH-3T3 cells transformed by v-src released PGE2 at wild-type levels after exposure to PDGF. Determination of total water-soluble inositol phospholipids and changes in the specific activities of phosphatidylcholine in control and EJ-ras-transfected cells demonstrated that PDGF-stimulated phospholipase C and A2 activities are inhibited in the EJ-ras-transfected cells.This publication has 29 references indexed in Scilit:
- Inhibition of receptor-mediated release of arachidonic acid by pertussis toxinCell, 1984
- The product of ras is a GTPase and the T24 oncogenic mutant is deficient in this activityNature, 1984
- Acquisition of transforming properties by alternative point mutations within c-bas/has human proto-oncogeneNature, 1983
- Identification of transforming gene in two human sarcoma cell lines as a new member of the ras gene family located on chromosome 1Nature, 1983
- Activation of the T24 bladder carcinoma transforming gene is linked to a single amino acid changeNature, 1982
- A point mutation is responsible for the acquisition of transforming properties by the T24 human bladder carcinoma oncogeneNature, 1982
- Mechanism of activation of a human oncogeneNature, 1982
- Isolation and preliminary characterization of a human transforming gene from T24 bladder carcinoma cellsNature, 1982
- Regulatory role of cyclic adenosine 3′,5′-monophosphate on the plattelet cyclooxygenase and platelet functionBiochimica et Biophysica Acta (BBA) - General Subjects, 1979
- A RAPID METHOD OF TOTAL LIPID EXTRACTION AND PURIFICATIONCanadian Journal of Biochemistry and Physiology, 1959