Nitric oxide decreases surfactant protein A gene expression in H441 cells.
OBJECTIVE
To study the effects of nitric oxide (NO) on surfactant protein A (SP-A) gene expression.


METHODS
In vitro study.


METHODS
A human lung tumor cell line (H441) representative of distal respiratory epithelium.


METHODS
Cells were treated with the NO donor S-nitroso-N-acetyl penicillamine (SNAP) at concentrations ranging from 0.3 to 3.0 mM for 24 hrs.


RESULTS
Northern blot analyses using a radiolabeled cDNA probe for human SP-A demonstrated that SNAP modestly (approximately 30%) decreased SP-A mRNA expression in a dose-dependent manner. Western blot analyses using a polyclonal anti-human SP-A antibody demonstrated that SNAP also decreased SP-A peptide expression. mRNA stability assays demonstrated that SNAP did not affect the half-life of SP-A mRNA. Cell viability assays demonstrated that SNAP slightly decreased cell viability compared with control cells. There were no significant differences in cell viability among cells treated with the different concentrations of SNAP.


CONCLUSIONS
NO decreases in vitro SP-A gene expression by approximately 30% in a human lung tumor cell line representative of distal respiratory epithelium. This effect does not occur at the posttranscriptional level and cannot be entirely accounted for by changes in cell viability. The inhibitory effect of NO demonstrated in this study is of relatively small magnitude and it is therefore difficult to make strong conclusions regarding biological relevance. However, these data, coupled with previous data demonstrating that NO negatively affects surfactant function, suggest that NO has the potential to negatively impact surfactant homeostasis.
Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
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Ayad
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Wong
D015152:Blotting, Northern; D015153:Blotting, Western; D015342:DNA Probes; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011510:Proteolipids / Q000235:genetics / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured / Q000378:metabolism
D015342:DNA Probes; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; C110881:S-nitro-N-acetylpenicillamine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D010396:Penicillamine