title: 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.affiliation: Howard Hughes Medical Institute/National Institutes of Health Research Scholars Program, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Kamrava
authors.forename: Fiona
authors.initials: F
authors.lastname: Simpkins
authors.forename: Emilyn
authors.initials: E
authors.lastname: Alejandro
authors.forename: Chad
authors.initials: C
authors.lastname: Michener
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Meltzer
authors.forename: Elise C
authors.initials: EC
authors.lastname: Kohn
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015152:Blotting, Northern; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D002614:Chelating Agents / Q000494:pharmacology; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D016232:Endothelins / Q000494:pharmacology*; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D008246:Lysophospholipids / Q000494:pharmacology*; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000378:metabolism* / Q000473:pathology; D037342:Pertussis Toxin / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D000077153:Progranulins; D014407:Tumor Cells, Cultured
chemical_list: D000276:Adjuvants, Immunologic; D002614:Chelating Agents; D016232:Endothelins; D020662:Guanine Nucleotide Exchange Factors; D036341:Intercellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D000077153:Progranulins; C116122:RAPGEF3 protein, human; D005576:Colforsin; D004533:Egtazic Acid; D002772:Cholera Toxin; D000242:Cyclic AMP; D011065:Poly(ADP-ribose) Polymerases; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C032881:lysophosphatidic acid