Lysophosphatidic acid and endothelin-induced proliferation of ovarian cancer cell lines is mitigated by neutralization of granulin-epithelin precursor (GEP), a prosurvival factor for ovarian cancer.

Abstract

Granulin-epithelin precursor (GEP/progranulin) is an autocrine growth factor for ovarian cancer. We examined the production and function of GEP and report that: (1) GEP production is regulated by endothelin (ET-1), lysophosphatidic acid (LPA), and cAMP; (2) cAMP signals GEP production through exchange protein activated by cAMP (EPAC); (3) ET-1 and cAMP/EPAC induce GEP through ERK1/2; and (4) neutralization of GEP results in apoptosis. Exposure of HEY-A8 and OVCAR3 ovarian cancer cells to LPA and ET-1 yielded GEP production and secretion in a dose- and time-dependent fashion; neither stimulated significant concentrations of cAMP directly. Stimulation of cAMP production with pertussis and cholera toxin, or forskolin induced GEP in a PKA-independent fashion. EPAC, an intracellular cAMP receptor, is activated specifically by the cAMP analog, 8-CPT-2'-O-Me-cAMP (8-CPT); 8-CPT treatment stimulated GEP production and secretion. The MEK inhibitor, U0126, abrogated GEP production in response to ET-1 and 8-CPT, confirming involvement of MAPK. A partial inhibition of basal and stimulated GEP production was observed when cells were treated with a internal calcium chelator, BAPTA. Neutralizing anti-GEP antibody reversed basal as well as LPA, ET-1 and 8-CPT-induced ovarian cancer cell growth and induced apoptosis as demonstrated by caspase-3 and PARP cleavage, DNA fragmentation, and nuclear condensation. These results indicate that GEP is a growth and survival factor for ovarian cancer, induced by LPA and ET-1 and cAMP/EPAC through ERK1/2.

• Authors: Mitchell Kamrava, Fiona Simpkins, Emilyn Alejandro, Chad Michener, Elizabeth Meltzer, Elise C Kohn
• Journal: Oncogene (Oncogene) Vol. 24 Issue 47 Pg. 7084-93 (Oct 27 2005) ISSN: 0950-9232 [Print] England
• PMID: 16044162 (Publication Type: Journal Article)

Chemical References

• Adjuvants, Immunologic
• Chelating Agents
• Endothelins
• Guanine Nucleotide Exchange Factors
• Intercellular Signaling Peptides and Proteins
• Lysophospholipids
• Progranulins
• RAPGEF3 protein, human
• Colforsin
• Egtazic Acid
• Cholera Toxin
• Cyclic AMP
• Poly(ADP-ribose) Polymerases
• Pertussis Toxin
• Cyclic AMP-Dependent Protein Kinases
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• MAP Kinase Kinase 1
• CASP3 protein, human
• Caspase 3
• Caspases
• 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
• lysophosphatidic acid

Topics

• Adjuvants, Immunologic (pharmacology)
• Apoptosis (drug effects)
• Blotting, Northern
• Blotting, Western
• Caspase 3
• Caspases (metabolism)
• Cell Nucleus (drug effects, metabolism)
• Cell Proliferation (drug effects)
• Chelating Agents (pharmacology)
• Cholera Toxin (pharmacology)
• Colforsin (pharmacology)
• Cyclic AMP (metabolism)
• Cyclic AMP-Dependent Protein Kinases (metabolism)
• Egtazic Acid (analogs & derivatives, pharmacology)
• Endothelins (pharmacology)
• Female
• Guanine Nucleotide Exchange Factors (metabolism)
• Humans
• Intercellular Signaling Peptides and Proteins (chemistry, immunology, metabolism)
• Lysophospholipids (pharmacology)
• MAP Kinase Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 1 (metabolism)
• Mitogen-Activated Protein Kinase 3 (metabolism)
• Ovarian Neoplasms (metabolism, pathology)
• Pertussis Toxin (pharmacology)
• Poly(ADP-ribose) Polymerases (metabolism)
• Progranulins
• Tumor Cells, Cultured