Claudin 1 Mediates TNFα-Induced Gene Expression and Cell Migration in Human Lung Carcinoma Cells

Abstract

Epithelial-mesenchymal transition (EMT) is an important mechanism in carcinogenesis. To determine the mechanisms that are involved in the regulation of EMT, it is crucial to develop new biomarkers and therapeutic targets towards cancers. In this study, when TGFβ1 and TNFα were used to induce EMT in human lung carcinoma A549 cells, we found an increase in an epithelial cell tight junction marker, Claudin 1. We further identified that it was the TNFα and not the TGFβ1 that induced the fibroblast-like morphology changes. TNFα also caused the increase in Claudin-1 gene expression and protein levels in Triton X-100 soluble cytoplasm fraction. Down-regulation of Claudin-1, using small interfering RNA (siRNA), inhibited 75% of TNFα-induced gene expression changes. Claudin-1 siRNA effectively blocked TNFα-induced molecular functional networks related to inflammation and cell movement. Claudin-1 siRNA was able to significantly reduce TNF-enhanced cell migration and fibroblast-like morphology. Furthermore, over expression of Claudin 1 with a Claudin 1-pcDNA3.1/V5-His vector enhanced cell migration. In conclusion, these observations indicate that Claudin 1 acts as a critical signal mediator in TNFα-induced gene expression and cell migration in human lung cancer cells. Further analyses of these cellular processes may be helpful in developing novel therapeutic strategies.

Native matrix-based human lung alveolar tissue model in vitro: studies of the reparatory actions of mesenchymal stem cells

“…Similarly, LPS and CSE exposure also suppresses cell proliferation and levels of beta-catenin protein, e-cadherin protein and caveolin-1 mRNA in our native matrix model. In corroboration, recent studies also show that besides the regulation of barrier functions, tight junctions are important for cell cycle, cell migration, proliferation and regeneration (Kasper et al 1995;Phillips et al 2008;Flozak et al 2010;Shiozaki et al 2012). In addition, MSC exhibited ability to modulate tight junctions-associated proteins e-cadherin and betacatenin when added together with CSE and LPS in our model.…”

Inflammatory mediators, tumor necrosis factor-α and interferon-γ, induce EMT in human PTC cell lines

“…TNF-α-induced EMT has been reported in numerous tumor types; however, EMT induced by IFN-γ alone has rarely been observed (11,22,23). RT-qPCR was used to measure the expression levels of epithelial cell marker, E-cadherin, and the mesenchymal cell markers, N-cadherin and vimentin, in epithelial cell lines, and their expression was used as a measure of EMT.…”

“…EMT was initially reported in embryonic development; however, it also occurs during tumor metastasis (14,15) and appears to be common in PTC invasion (16)(17)(18)(19). Transforming growth factor-β (TGF-β) and epidermal growth factor (EGF) are inflammatory cytokines that are able to stimulate EMT in thyroid cancer cells or thyroid cells cultured ex vivo (20,21 of TNF-α and IFN-γ have been demonstrated to induce invasion and metastasis of cancer (11,12,(22)(23)(24) via mechanisms involving the SMAD, NF-κB, AKT/GSK-3β and JAK/STAT signaling pathways. Thus, EMT represents a convergence point between inflammation and the progression of cancer (25); however, the mechanisms through which inflammation is involved in the different stages of tumor invasion, intravasation and subsequent metastasis to the distant organ sites remain poorly defined (26).…”

The expression of Claudin 1 correlates with β-catenin and is a prognostic factor of poor outcome in gastric cancer

“…CLDN1 upregulates the repressor ZEB-1 to reduce expression of E-cadherin in colon cancer cells, increasing their invasive activity and reducing anoikis (23). CLDN1 mediates TNFα-induced gene expression and cell migration in human lung carcinoma cells (24). The CLDN1 expression was correlated with subtypes in breast (25,26) and lung (27) cancer.…”