The effects of dexamethasone and betamethasone on surfactant protein-B messenger RNA expression in human type II pneumocytes and human lung adenocarcinoma cells

Objective: The purpose of this study was to compare the effect of a single 48-hour exposure to betamethasone or dexamethasone in the NCI-H441 cell line and in human type II pneumocytes. Study design: NCI-H441 cells were exposed 48 hours to varying concentrations of betamethasone or dexamethasone (10 ^-10 to 10^-7 mol/L) alone or in combination with 1 mmol/L dibutyryl cyclic adenosine monophosphate. Likewise, human type II pneumocytes were exposed 48 hours to varying concentrations of betamethasone or dexamethasone (10^-9 to 10^-7 mol/L) alone or in combination with 1 mmol/L dibutyryl cyclic adenosine monophosphate. The measured outcome was the stimulatory effect on surfactant protein B gene transcription as expressed by surfactant protein B messenger RNA accumulation. The experiment was conducted 5 times in NCI-H441 cells and 6 times in type II cells, in parallel with control. Surfactant protein B messenger RNA was determined at control level and 48 hours after exposure by quantitative reverse transcription-polymerase chain reaction. Results: A similar dose-dependent response in surfactant protein B messenger RNA expression was seen with both betamethasone and dexamethasone. In human type II pneumocytes, the inductive profile of surfactant protein B messenger RNA after 48-hour exposure to betamethasone or dexamethasone was similar to that seen in the NCI-H441 cells. Conclusion: Dexamethasone and betamethasone achieved similar dose-response patterns of surfactant protein-B expression in vitro.