Constitutive expression of inducible nitric oxide synthase in human bronchial epithelial cells induces c-fos and stimulates the cGMP pathway.
Two major roles have been defined for nitric oxide (NO): cell-cell communication mediated by the stimulation of cyclic guanosine 3',5'-monophosphate (cGMP) synthesis and cytotoxicity by direct or indirect interaction of the free radical NO with cellular targets. Thus, pathologic states might result from an alteration of NO pathways, e.g., by deregulated activity of NO synthase. To investigate this hypothesis, we introduced the murine-inducible NO synthase (iNOS) sequence into immortalized human bronchial epithelial cells (BEAS-2B). iNOS activity, measured by conversion of [14C]arginine to [14C]citrulline in the presence of 1 mM EGTA, was higher than 100 pmol/min/mg protein in early passages of iNOS-transfected cells but decreased with cell subculturing. No iNOS activity could be detected in control vector-transfected cells. NO stimulated cGMP production in iNOS-transfected cells, and this effect was inhibited by the iNOS inhibitor NG-monomethyl-L-arginine. In addition, NO production induced c-fos expression and did not interfere with clonal cell growth. These results suggest that BEAS-2B cells constitute a suitable model to study the consequences of iNOS activity on signal transduction pathways in bronchial epithelium.
Felley-Bosco
E
E
Laboratory of Human Carcinogenesis, National Cancer Institute, Bethesda, Maryland.
Ambs
S
S
Lowenstein
C J
CJ
Keefer
L K
LK
Harris
C C
CC
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis*; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis; D001120:Arginine / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D001980:Bronchi / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002455:Cell Division; D002461:Cell Line, Transformed; D002956:Citrulline / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D017931:DNA Primers; D004790:Enzyme Induction; D004848:Epithelium / Q000378:metabolism; D015870:Gene Expression; D016762:Genes, fos; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D019001:Nitric Oxide Synthase; D016133:Polymerase Chain Reaction; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D013539:Simian virus 40 / Q000235:genetics; D014162:Transfection
D000952:Antigens, Polyomavirus Transforming; D002250:Carbon Radioisotopes; D017931:DNA Primers; D016760:Proto-Oncogene Proteins c-fos; D002956:Citrulline; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D006152:Cyclic GMP