Transforming growth factor beta and dexamethasone suppress the expression of Fc epsilon receptor 2 (CD23) on a human eosinophilic cell line EoL-3

Glucocorticoid induces mesenchymal-to-epithelial transition and inhibits TGF-β1-induced epithelial-to-mesenchymal transition and cell migration

Epithelial-to-mesenchymal transition (EMT) has been implicated in various physiological and pathological events. In this study, we found that the synthetic glucocorticoid dexamethasone (Dex) can inhibit transforming growth factor-beta1-induced EMT and cell migration. We also demonstrated that Dex inhibits EMT through a mechanism involving the suppression of ROS generation. Surprisingly, Dex alone induced mesenchymal-to-epithelial transition (MET). Dexamethasone treatment abolished Snail1 binding to the E-cadherin promoter, suggesting that suppression of Snail1 contributes to the above roles of Dex. Our findings demonstrate that Dex functions as both a suppressor of EMT and as an inducer of MET and therefore may be implicated in certain pathophysiological events.

Regulation of the expression of leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) on a human eosinophilic leukemia cell line EoL-3

The effects of several cytokines and phorbol myristate acetate (PMA) on LFA-1 and ICAM-1 expression on a human eosinophilic leukemia cell line, EoL-3, were investigated and compared with those of a human monocytic leukemia cell line, U937. EoL-3 cells expressed large amounts of LFA-1 and small amounts of ICAM-1, and their expression was regulated similarly in EoL-3 cells and U937 cells. Interferon-gamma (IFN-gamma) enhanced ICAM-1 expression but not LFA-1 expression, and PMA augmented both LFA-1 and ICAM-1 expression. IFN-gamma and PMA showed an additive effect on ICAM-1 expression. These results collectively suggest that expression of LFA-1 and ICAM-1 is regulated differently and that IFN-gamma and PMA regulate the expression through different mechanisms. PMA but not IFN-gamma induced homotypic adhesion of EoL-3 and U937 cells, suggesting that PMA but not IFN-gamma activated the adhesive function of these cells. Staurosporin, an inhibitor of protein kinases (PKs), partly suppressed IFN-gamma- and PMA-augmented expression of ICAM-1 on EoL-3 and U937 cells, but did not affect PMA-augmented LFA-1 expression, suggesting that staurosporin-sensitive PKs are involved in IFN-gamma- and PMA-augmented ICAM-1 expression but not in PMA-augmented LFA-1 expression. The role of protein kinase C (PK-C) in these mechanisms was not revealed because a PK-C inhibitor, H-7, did not show any definitive effect on IFN-gamma- and PMA-induced expression of LFA-1 and ICAM-1. Moreover, cyclic AMP (cAMP)- and cGMP-dependent pathways were not shown to be involved in the augmentation of the expression of these molecules.

EoL-1, a human eosinophilic cell line

EoL-1 cells, a recently established human eosinophilic leukemia cell line, have cytological features of myeloblasts under normal culture conditions, and differentiate not only phenotypically but also functionally into eosinophils by a number of stimuli. EoL-1 cells are particularly useful for analyzing leukemic cell differentiation and the properties of malignant eosinophils. EoL-1 cells are also a useful in vitro model for studying human eosinophil functions and their regulation.