MicroRNA-9 and Cell Proliferation in Lipopolysaccharide and Dexamethasone-Treated Naïve and Desialylated A549 Cells Grown in Cigarette Smoke Conditioned Medium
In this study we assessed microRNA-9 (miR-9) levels (RT-PCR) and cell proliferation (flow cytometry) in naïve and desialylated human alveolar epithelial cells (A549 cells), grown for 24 h in cigarette smoke-conditioned medium. Cells were additionally treated with lipopolysaccharide (LPS) and/or dexamethasone. Proliferation positively correlated with miR-9 levels in both naïve and desialylated cells. Cigarette smoke decreased miR-9 levels in both cell types by about three-fold but there was no significant correlation between both parameters. Dexamethasone was without substantial effect on cigarette smoke-induced changes in proliferation of naïve cells, but some normalization was observed in desialylated cells. Dexamethasone increased miR-9 levels in both cell types grown in cigarette smoke-medium but the effect was stronger in desialylated cells. LPS increased cell proliferation and miR-9 by more than six-fold only in naïve cells, while correlation coefficient for both parameters in cigarette smoke-LPS group was 0.41. Herein we identify miR-9 as the cigarette smoke (decrease) and LPS-responsive but dexamethasone-unresponsive microRNA. It is possible that increased miR-9 levels in naïve A549 cells treated with LPS may be related to the activation of Toll-like receptor 4. Moreover, differences in cell response (both miR-9 and proliferation) to dexamethasone in naïve and desialylated cells may point to non-genomic dexamethasone effects.
KeywordsAlveolar epithelial cells Cell proliferation Cigarette smoke Dexamethasone Lipopolysaccharide microRNA-9 Sialic acid
Conflicts of Interest
The authors had no conflicts of interest to declare in relation to this article.
- Schembri F, Sridhar S, Perdomo C, Gustafson AM, Zhang X, Ergun A, Lu J, Liu G, Zhang X, Bowers J, Vaziri C, Ott K, Sensinger K, Collins JJ, Brody JS, Getts R, Lenburg ME, Spira A (2009) MicroRNAs as modulators of smoking-induced gene expression changes in human airway epithelium. Proc Natl Acad Sci U S A 106:2319–2324CrossRefGoogle Scholar