Down-Regulation of E-Cadherin in Human Bronchial Epithelial Cells Leads to Epidermal Growth Factor Receptor-Dependent Th2 Cell-Promoting Activity

Abstract

Airway epithelial cells are well-known producers of thymus- and activation-regulated chemokine (TARC), a Th2 cell-attracting chemokine that may play an important role in the development of allergic airway inflammation. However, the mechanism responsible for up-regulation of TARC in allergy is still unknown. In the asthmatic airways, loss of expression of the cell-cell contact molecule E-cadherin and reduced epithelial barrier function has been observed, which may be the result of an inadequate repair response. Because E-cadherin also suppressed multiple signaling pathways, we studied whether disruption of E-cadherin-mediated cell contact may contribute to increased proallergic activity of epithelial cells, e.g., production of the chemokine TARC. We down-regulated E-cadherin in bronchial epithelial cells by small interference RNA and studied effects on electrical resistance, signaling pathways, and TARC expression (by electric cell-substrate impedance sensing, immunodetection, immunofluorescent staining, and real-time PCR). Small interference RNA silencing of E-cadherin resulted in loss of E-cadherin-mediated junctions, enhanced phosphorylation of epidermal growth factor receptor (EGFR), and the downstream targets MEK/ERK-1/2 and p38 MAPK, finally resulting in up-regulation of TARC as well as thymic stromal lymphopoietin expression. The use of specific inhibitors revealed that the effect on TARC is mediated by EGFR-dependent activation of the MAPK pathways. In contrast to TARC, expression of the Th1/Treg cell-attracting chemokine RANTES was unaffected by E-cadherin down-regulation. In summary, we show that loss of E-cadherin-mediated epithelial cell-cell contact by damaging stimuli, e.g., allergens, may result in reduced suppression of EGFR-dependent signaling pathways and subsequent induction of Th2 cell-attracting molecule TARC. Thus, disruption of intercellular epithelial contacts may specifically promote Th2 cell recruitment in allergic asthma.

Airway epithelial cell differentiation during lung organogenesis requires C/EBPα and C/EBPβ

“…E-cadherin was, in contrast to the cell membrane localization detected in SFTPC-Cre À littermates, weakly expressed in the cytoplasm of Cebpa DLE ; Cebpb DLE mice. E-cadherin has also been suggested to play a role in the dysfunctional epithelial barrier function observed in asthmatics (Heijink et al, 2007). Impaired C/EBP signaling, as detected in inflammatory lung diseases, may thus possibly affect epithelial barrier function.…”

Characterisation of cell adhesion in airway epithelial cell types using electric cell–substrate impedance sensing

“…The human bronchial epithelial cell line 16HBE14o-was kindly provided by D.C. Gruenert (University of California, San Francisco, CA, USA) and cultured in Eagle minimum essential medium (EMEM)/10% fetal calf serum (FCS; Biowhittaker, Verviers, Belgium) on collagen-coated flasks as described previously [9]. Human bronchial BEAS-2B cells were cultured in RPMI medium/10% FCS on collagen-coated flasks.…”

“…Small interfering RNA downregulation of E-cadherin E-cadherin gene expression was downregulated in the 16HBE14o-cells by use of small interfering RNA (siRNA), as described previously [9]. In brief, cells were seeded at 5610 4 cells?well -1 and transfected with E-cadherin-targeted siRNA/nontargeting control oligonucleotides (Eurogentec, Liège, Belgium) at a final concentration of 20 mM using Oligofectamine (Invitrogen Corporation, Carlsbad, CA, USA).…”

“…Total cell lysates were obtained by resuspension of the cells in Laemmli buffer, and immunodetection was performed as described previously [9], using anti-E-cadherin (Santa Cruz Biotechnology, Santa Cruz, CA, USA) and anti-ZO-1 (Zymed, San Francisco, CA, USA).…”

Relevance of E-cadherin expression to EGFR-TKI molecular targeted therapy sensitivity/resistance and its clinical significance

“…Therefore, binding of the ligand to the EGFR receptor may cause downregulation of E-cadherin expression and initiate the epithelial mesenchymal transition (Yasmeen et al, 2006). E-cadherin is a calcium-dependent transmembrane protein capable of intercellular adhesion, and EGFR of E-cadherin may be activated for phosphorylation when the cellular calcium concentration increases (Pece and Gutkind, 2000;Heijinki et al, 2007). In addition, E-cadherin can bind to EGFR receptors through its extracellular domain to reduce the activity of these receptors as well as EGF binding affinity (Qian et al, 2004).…”