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. 2012 Apr 15;52(8):1437-42.
doi: 10.1016/j.freeradbiomed.2012.01.024. Epub 2012 Feb 4.

Cigarette smoke extract stimulates epithelial-mesenchymal transition through Src activation

Hongqiao Zhang  1 , Honglei Liu, Zea Borok, Kelvin J A Davies, Fulvio Ursini, Henry Jay Forman
Affiliations

Cigarette smoke extract stimulates epithelial-mesenchymal transition through Src activation

Hongqiao Zhang et al. Free Radic Biol Med. .

Abstract

Epithelial-mesenchymal transition (EMT) is implicated in the pathogenesis of lung fibrosis and cancer metastasis, two conditions associated with cigarette smoke (CS). CS has been reported to promote the EMT process. CS is the major cause of lung cancer and nearly half of lung cancer patients are active smokers. Nonetheless, the mechanism whereby CS induces EMT remains largely unknown. In this study we investigated the induction of EMT by CS and explored the underlying mechanisms in the human non-small-cell lung carcinoma (H358) cell line. We demonstrate that exposure to an extract of CS (CSE) decreases E-cadherin and increases N-cadherin and vimentin, markers of EMT, in H358 cells cultured in RPMI 1640 medium with 1% fetal bovine serum. Pretreatment with N-acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, abrogated changes in these EMT markers. In addition, CSE activated Src kinase (shown as increased phosphorylation of Src at Tyr418), and the Src kinase inhibitor PP2 inhibited CS-stimulated EMT changes, suggesting that Src is critical in CSE-stimulated EMT induction. Furthermore, NAC treatment abrogated CSE-stimulated Src activation. However, co-incubation with catalase had no effect on CSE-mediated Src activation. Finally, acrolein, an unsaturated aldehyde present in CSE, caused Src activation. Taken together, these data suggest that CSE initiates EMT through Src, which is activated by CS through redox modification.

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Figures

Figure 1
Figure 1
CSE induced changes in epithelial and mesenchymal proteins in H358 cells. H358 cells were treated with different concentrations of CSE in 1% FBS medium for 72 h, and cell lysates were assayed for EMT proteins by western analysis. *, P<0.05 compared with control, N=3.
Figure 1
Figure 1
CSE induced changes in epithelial and mesenchymal proteins in H358 cells. H358 cells were treated with different concentrations of CSE in 1% FBS medium for 72 h, and cell lysates were assayed for EMT proteins by western analysis. *, P<0.05 compared with control, N=3.
Figure 2
Figure 2
NAC pretreatment abrogated changes in epithelial and mesenchymal proteins caused by CSE. *, P<0.05 compared with control, N=3.
Figure 2
Figure 2
NAC pretreatment abrogated changes in epithelial and mesenchymal proteins caused by CSE. *, P<0.05 compared with control, N=3.
Figure 3
Figure 3
Src activation by CSE. H358 cells were exposed to 10% CSE for different times. Phosphorylation of Src at Tyr418 was determined by western analysis.
Figure 4
Figure 4
Inhibition of Src suppressed changes in epithelial and mesenchymal proteins by CSE. H358 cells were pretreated with or without PP2 for 1 h and then exposed to 10% CSE for 72 h. The cell lysates were assayed for EMT-related proteins by western analysis. *, P<0.05 compared with control, N=3.
Figure 5
Figure 5
NAC inhibited CSE-mediated Src activation. H358 cells were pretreated with/without 2mM NAC for 4 h and then exposed to 10% CSE for 15 min. Phosphorylation of Src at Tyr418 and total Src were determined with Western blots. *, P<0.05 compared with control, N=3.
Figure 6
Figure 6
Catalase effect on CSE-mediated Src activation. catalase (final concentration 400 U/ml) was added to culture medium immediately before H358 cells were exposed to 10% CSE. Phosphorylation of Src at Tyr418 and total Src were determined with Western blots. *, P<0.05 compared with control, N=3.
Figure 7
Figure 7
Src activation by acrolein. H358 cells were exposed to acrolein (15 PM) for indicated time and the phosphorylation of Src at Tyr418 and total Src were determined with Western blots.
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References

    1. Willis BC, Borok Z. TGF-beta-induced EMT: mechanisms and implications for fibrotic lung disease. Am J Physiol Lung Cell Mol Physiol. 2007;293(3):L525–34. - PubMed
    1. Gharaee-Kermani M, et al. Recent advances in molecular targets and treatment of idiopathic pulmonary fibrosis: focus on TGFbeta signaling and the myofibroblast. Curr Med Chem. 2009;16(11):1400–17. - PubMed
    1. Yauch RL, et al. Epithelial versus mesenchymal phenotype determines in vitro sensitivity and predicts clinical activity of erlotinib in lung cancer patients. Clin Cancer Res. 2005;11(24 Pt 1):8686–98. - PubMed
    1. Soltermann A, et al. Prognostic significance of epithelial-mesenchymal and mesenchymal-epithelial transition protein expression in non-small cell lung cancer. Clin Cancer Res. 2008;14(22):7430–7. - PubMed
    1. Baumgartner KB, et al. Cigarette smoking: a risk factor for idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 1997;155(1):242–8. - PubMed

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