Wheatgrass Extract Ameliorates Hypoxia-induced Mucin Gene Expression in A549 cells

BACKGROUND: Wheatgrass is known to have antioxidant, antiaging, and anti-inflammatory effect. However, its protective effect against hypoxia is not yet evaluated. OBJECTIVE: In this study, we evaluated the protective and anti-inflammatory effect of wheatgrass against the hypoxia in airway epithelial cells. MATERIALS AND METHODS: A549 human lung adenocarcinoma cells were incubated in a hypoxic condition (CO(2) 5%/O(2) 1%) for 24 hr in the presence of different concentration of wheatgrass 50, 75, 100, and 150 μg/mL, and the magnitude of each immunologic response produced by the A549 cells was compared. The mRNA expression level of mucin gene (MUC), 5A, 5B, 8, GM-CSF, TNF-α, and VEGF were evaluated by using real-time polymerase chain reaction. The MUC proteins level before and after knocking out the hypoxia-inducible factor (hif)-1α via short interfering (si) RNA transfection were assessed by immunoblot analysis. Accordingly, the involved cell signaling pathway was evaluated by immunoblot analysis. RESULTS: The inflammatory cytokines (GM-CSF, TNF- α) and the expressions of MUC 5A, 5B, and 8 were augmented by hypoxia. The augmented MUC expression was decreased by the wheatgrass extract administration. Hif-1α gene expression after hypoxia exposure was decreased by wheatgrass. Knockdown of hif-1α by siRNA reduced the mucin gene expression and which was more enhanced by wheatgrass extract. CONCLUSION: Theses results suggest that wheatgrass may be useful in the treatment of sinonasal disease by inhibiting mucus hypersecretion in airway epithelium. SUMMARY: Wheatgrass extract decreases the hypoxia-induced MUC 5A, 5B and 8 expression. Hif-1α gene expression after hypoxia exposure was decreased by wheatgrass. Wheatgrass inhibits p44/42 phosphorylation in hypoxia-exposed airway epithelial cells. Abbreviations used: A549: human lung adenocarcinoma cells, GM-CSF: granulocyte-macrophage colony stimulating factor, HIF: hypoxia inducible factor, IL: interleukin, MUC: mucin, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, TNF: tumor necrosis factors, VEGF: vascular endothelial growth factor, si RNA: short interfering RNA