In vitro quantification of dexamethasone-induced surfactant protein B expression in human lung cells.
OBJECTIVE
To determine whether the effect of a single 48-h exposure to dexamethasone in human lung cells is limited to 7-8 days.


METHODS
We used the NCI-H441 cell line, in which stability can be maintained beyond 7 days. The outcome was the stimulatory effect of dexamethasone on surfactant protein B (SP-B) gene transcription as expressed by SP-B mRNA accumulation. The experiment was conducted five times, in parallel with control. SP-B mRNA was determined at baseline, 48 h after dexamethasone exposure, and at 48-h intervals thereafter, up to 14 days, by quantitative reverse transcription polymerase chain reaction. Comparisons were made by the Mann-Whitney test.


RESULTS
In conditions of our experiment, the inductive profile of SP-B mRNA after exposure to dexamethasone demonstrated maximal stimulation at 48 h (13-fold over control). Subsequently, there was a decline in mRNA, with return to near control levels by day 8, suggesting reversibility of dexamethasone action.


CONCLUSIONS
Our data support the view that the surfactant-inducing properties of corticosteroids are limited to 7-8 days.
Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
A C
AC
Vidaeff
S M
SM
Ramin
L C
LC
Gilstrap
J L
JL
Alcorn
D045744:Cell Line, Tumor; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D037701:Pulmonary Surfactant-Associated Protein B / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D005938:Glucocorticoids; D037701:Pulmonary Surfactant-Associated Protein B; D012334:RNA, Neoplasm; D003907:Dexamethasone