title: Exogenous nitric oxide upregulates p21(waf1/cip1) in pulmonary microvascular smooth muscle cells.
abstract: The histopathology of chronic pulmonary hypertension includes microvascular proliferation and neointimal formation. Nitric oxide (NO) has been implicated in the regulation of these mechanisms, but how NO controls microvascular proliferation and its effect on pulmonary microvascular cells is still unclear. In this study, we characterized the in vitro effects of NO on rat pulmonary microvascular smooth muscle cell (PMVSMC) proliferation and investigated the contribution of the p42/44 mitogen-activated protein kinase (MAPK) pathway and p21(waf1/cip1) induction to this response. NO donors inhibited PMVSMC proliferation in a dose-dependent manner. In the presence of hypoxia, the degree of inhibition was significantly enhanced. This inhibition was reversible and independent of apoptosis. The soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) had no impact on proliferation rates, suggesting a cyclic guanosine monophosphate-independent process. Administration of MEK1/2 inhibitors failed to abrogate the antimitotic effect of NO. There was a two- fold induction of the cyclin-dependent kinase inhibitor p21 in PMVSMC treated with NO donors. Under hypoxic conditions, NO caused a three-fold increase in p21 levels. These results demonstrate that NO inhibits PMVSMC proliferation and that this inhibition is not the result of p42/44 MAPK activation. The ability of NO to induce p21 upregulation may be a mechanism by which it exerts antiproliferative effects in PMVSMC.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Stotz
authors.forename: Dechun
authors.initials: D
authors.lastname: Li
authors.forename: Roger A
authors.initials: RA
authors.lastname: Johns
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D008297:Male; D008833:Microcirculation; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000008:administration & dosage / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000008:administration & dosage / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026423:S-Nitroso-N-Acetylpenicillamine / Q000008:administration & dosage / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C493958:Cdkn1a protein, rat; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; C093285:NOC 18; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D026423:S-Nitroso-N-Acetylpenicillamine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D006152:Cyclic GMP