Tumor necrosis factor-α enhances both epithelial-mesenchymal transition and cell contraction induced in A549 human alveolar epithelial cells by transforming growth factor-β1

Abstract

Recently, epithelial-mesenchymal transition (EMT) has been reported to contribute to tissue fibrosis through enhanced transforming growth factor (TGF)-beta1 signaling. Tumor necrosis factor (TNF)-alpha has also been implicated in tissue fibrosis. Therefore, the authors investigated whether TNF-alpha affected TGF-beta1-induced EMT. Cultured alveolar epithelial cells (A549 cells) were stimulated with TGF-beta1 (5 ng/mL), with/without TNF-alpha (10 ng/mL). TGF-beta1 induced EMT of A549 cells, with loss of E-cadherin and acquisition of vimentin. Combination of TNF-alpha with TGF-beta1 enhanced EMT, causing morphological changes, while quantitative polymerase chain reaction (PCR) showed suppression of E-cadherin mRNA and expression of vimentin mRNA. In addition, the gel contraction method revealed that cells that had undergone EMT acquired cell contractility, which is a feature of mesenchymal cells. Stimulation with TGF-beta1 induced cell contraction, as did TNF-alpha. Moreover, costimulation with TGF-beta1 and TNF-alpha enhanced the cell contraction. Although IFN-gamma suppressed spontaneous cell contraction, it did not suppress cell contraction, which was induced by TGF-beta1. In conclusion, TNF-alpha enhances not only EMT but also cell contraction induced by TGF-beta1. EMT might contribute to tissue fibrosis through induction of cell contraction.

Transforming Growth Factor-β1 (TGF-β1) Driven Epithelial to Mesenchymal Transition (EMT) is Accentuated by Tumour Necrosis Factor α (TNFα) via Crosstalk Between the SMAD and NF-κB Pathways

“…There are conflicting reports in the literature regarding the ability of TNFα to drive EMT in the absence of TGF-β1 with some groups reporting positive findings [15,16] and others negative findings [3,[17][18][19]. However, there is compelling evidence that TNFα is able to accentuate TGF-β1 driven EMT in a range of cell types [17,19,20].…”

“…Recently TNFα has been shown to accentuate TGF-β1 driven EMT in a range of cell types highlighting a potential link between EMT and inflammation [17][18][19][20][21][22][23]. However, the mechanisms responsible have been ill-defined and further studies are required to elucidate the signalling pathways involved so potential therapeutic targets to limit or even reverse inflammatory driven EMT can be identified.…”

“…However, there is compelling evidence that TNFα is able to accentuate TGF-β1 driven EMT in a range of cell types [17,19,20]. For example it has previously shown that TNFα can accentuate TGF-β1 driven EMT in primary bronchial epithelial cells causing dysregulated wound repair of the injured lung epithelium [21] and that TNFα can increase metastatic potential in human colonic epithelial organoid models of colon cancer by accentuating EMT [22].…”

Tumor necrosis factor α induces epithelial-mesenchymal transition and promotes metastasis via NF-κB signaling pathway-mediated TWIST expression in hypopharyngeal cancer

“…EMT is an important step during primary tumor metastasis. Although increasing evidence indicates that TNFα induces EMT and promotes cancer migration and invasion (19,22), the effect of TNFα on HNSCC remains undetermined.…”

An Assessment of Epithelial and Mesenchymal Phenotypes in Experimental and Clinical Pulmonary Fibrosis

“…Here we initially used a lung epithelial tumour cell line, A549, which is commonly used in EMT assays [22][23][24], to profile the TGFβ 1 -induced changes in EMT markers. A549 cells were treated with TGFβ 1 for 24 hours and a panel of EMT associated genes were measured.…”