title: Antiproliferative effect of sildenafil on human pulmonary artery smooth muscle cells.
abstract: Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction and by obstructive changes of the pulmonary vasculature including smooth muscle cell proliferation which leads to medial hypertrophy and subsequent luminal narrowing. Sildenafil, an orally active inhibitor of cGMP phosphodiesterase-type-5, exerts pulmonary vasodilator activity in PAH patients. We evaluated the effects of sildenafil on growth of cultured human pulmonary artery smooth muscle cells (PASMC). The results indicate that sildenafil reduced DNA synthesis stimulated by PDGF and dose dependently inhibited PASMC proliferation. These effects were paralleled by a progressive increase in cGMP content, followed by an accumulation of cAMP. The treatment with 8-bromo-cGMP or dibutyryl-cAMP mimicked all the effects of sildenafil. On the other hand, treatment of PASMC with inhibitors of cGMP-dependent protein kinase (PKG) or cAMP-dependent protein kinase (PKA) reversed the antiproliferative effect of sildenafil. In addition, sildenafil inhibited the phosphorylation of ERK, a converging point for several pathways leading to cell proliferation. This effect was partially reduced by PKG inhibition and completely abolished by PKA inhibition.We conclude that sildenafil exerts an antiproliferative effect on human PASMC that is mediated by an interaction between the cGMP-PKG and the cAMP-PKA activated pathways, leading to inhibition of PDGF-mediated activation of the ERK.
authors.affiliation: Department of Biochemistry, G. Moruzzi University of Bologna, Bologna, Italy. benedetta.tantini@unibo.it
authors.forename: Benedetta
authors.initials: B
authors.lastname: Tantini
authors.forename: Alessandra
authors.initials: A
authors.lastname: Manes
authors.forename: Emanuela
authors.initials: E
authors.lastname: Fiumana
authors.forename: Carla
authors.initials: C
authors.lastname: Pignatti
authors.forename: Carlo
authors.initials: C
authors.lastname: Guarnieri
authors.forename: Romano
authors.initials: R
authors.lastname: Zannoli
authors.forename: Angelo
authors.initials: A
authors.lastname: Branzi
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Galié
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000473:pathology; D011687:Purines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D010982:Platelet-Derived Growth Factor; D047428:Protein Kinase Inhibitors; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D006152:Cyclic GMP