Taken together, these findings suggest that HIF-1α inhibition suppresses the VEGF expression in lungs, specifically in tracheal epithelial Roscovitine cells, of allergic airway disease. 2ME2 was initially introduced as a direct angiogenetic inhibitor having antiproliferative and proapoptotic effects on endothelial cells. Recently, 2ME2 has been shown to inhibit activation of HIF-1α by suppressing HIF-1α

translation and its nuclear translocation 40. Therefore, on the basis of our present observations, we suggest that 2ME2 could reduce the levels of HIF-1α protein in the nuclear fractions from lung tissues and airway epithelial cells of OVA-treated mice through the inhibition of HIF-1α translation and its nuclear translocation, thereby suppresses the VEGF expression. However, the effects through other mechanisms

of 2ME2 cannot be overlooked. In addition, our results have also revealed a dramatic reduction in allergen-induced goblet cell hyperplasia in 2ME2-treated mice. Since Th2 cytokines, VEGF, T cells, and eosinophils are required to produce airway mucus accumulation and goblet cell degranulation 17, 41, 42, the decrease in allergen-induced goblet cell hyperplasia by 2ME2 may be attributed to a substantial drop in the levels of Th2 cytokines and LEE011 price VEGF as well as reduction in eosinophilia in OVA-treated mice. Meanwhile, VEGF also represents one of the most important targets preferentially selleckchem regulated by HIF-2α 43. HIF-2α, one isoform of HIF-α subunits, is also referred to as endothelial PAS domain protein-1 or HIF-1α-like factor and bears functional resemblance to HIF-1α regarding hypoxic stabilization and binding to HIF-1β, although it has also different roles in tumorigenesis 14, 44. In fact, HIF-2α can directly activate expression of genes encoding a number of pro-angiogenic factors, including VEGF, erythropoietin, angiopoietin, and Tie-2 receptors 11. In this study, we have found that HIF-2α protein and mRNA expression was substantially increased in primary tracheal epithelial cells isolated from OVA-treated mice and that transfection with

siRNA for HIF-2α into the cells reduced significantly the increase of HIF-2α and VEGF expression in primary tracheal epithelial cells (see the Supporting Information). These findings suggest that HIF-2α inhibition also suppresses OVA-induced VEGF expression in bronchial epithelial cells. PI3K catalyzes phosphorylation of phosphatidylinositol (4,5)-bisphosphate to form PIP3 in response to activation of either receptor tyrosine kinase, G-protein coupled receptors, or cytokine receptors, which ultimately regulate cell growth, differentiation, survival, proliferation, migration, and cytokine production 33, 34, 45. The class IA PI3K consists of a heterodimer composed of a 110-kD (p110α, β, δ) catalytic subunit and an adaptor protein (p85α, p85β, p55α, p55γ, p50α) 46.