title: Differential effects of stable prostacyclin analogs on smooth muscle proliferation and cyclic AMP generation in human pulmonary artery.
abstract: Primary pulmonary hypertension is characterized by increased pulmonary vascular resistance and smooth muscle proliferation. Stable analogs are increasingly being used to treat this disease, although no data exists comparing their effects on proliferation. We therefore investigated the antiproliferative activity of several prostacyclin (PGI(2)) analogs on human pulmonary arterial smooth muscle cells, including UT-15 and iloprost, analogs that have recently completed successful clinical trials. Serum-induced proliferation, as assessed by [(3)H]thymidine incorporation (30 h) or cell number (48 h), was significantly inhibited with a 10-fold difference in potency, ranking in effectiveness UT-15 > iloprost > cicaprost > beraprost. Effects were reversed by the adenylyl cyclase inhibitor, 2,5'dideoxyadenosine (DDA) but not SQ22536. Intracellular cyclic AMP (cAMP) was elevated by all analogs and inhibited by DDA, although SQ22536 was a highly variable inhibitor, suggesting that different pathways might mediate cAMP generation. UT-15 produced a significantly larger and more sustained increase in cAMP compared with other analogs, with iloprost being the weakest elevator. Thus, PGI(2) analogs potently inhibit proliferation of human pulmonary artery, probably via a cAMP-dependent pathway, although cAMP elevation in itself is not a good predictor of antiproliferative potency.
authors.affiliation: Centre for Clinical Pharmacology, Department of Medicine, University College London, Rayne Institute (4th Floor), 5 University Street, London W1C 6JJ, United Kingdom. l.clapp@ucl.ac.uk
authors.forename: Lucie H
authors.initials: LH
authors.lastname: Clapp
authors.forename: Paul
authors.initials: P
authors.lastname: Finney
authors.forename: Sally
authors.initials: S
authors.lastname: Turcato
authors.forename: Sandy
authors.initials: S
authors.lastname: Tran
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: Rubin
authors.forename: Andrew
authors.initials: A
authors.lastname: Tinker
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D015394:Molecular Structure; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D004791:Enzyme Inhibitors; D010982:Platelet-Derived Growth Factor; C048081:beraprost; D011464:Epoprostenol; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D016285:Iloprost; C043867:cicaprost; C427248:treprostinil