Multi-walled carbon nanotubes directly induce epithelial-mesenchymal transition in human bronchial epithelial cells via
- PDF / 2,109,478 Bytes
- 19 Pages / 595.276 x 790.866 pts Page_size
- 53 Downloads / 222 Views
RESEARCH
Open Access
Multi-walled carbon nanotubes directly induce epithelial-mesenchymal transition in human bronchial epithelial cells via the TGF-β-mediated Akt/GSK-3β/SNAIL-1 signalling pathway Manuela Polimeni1,2, Giulia Rossana Gulino1,2, Elena Gazzano1,2, Joanna Kopecka1, Arianna Marucco2,3, Ivana Fenoglio2,3,4, Federico Cesano3,4, Luisa Campagnolo5, Andrea Magrini5, Antonio Pietroiusti5, Dario Ghigo1,2ˆ and Elisabetta Aldieri1,2*
Abstract Background: Multi-walled carbon nanotubes (MWCNT) are currently under intense toxicological investigation due to concern on their potential health effects. Current in vitro and in vivo data indicate that MWCNT exposure is strongly associated with lung toxicity (inflammation, fibrosis, granuloma, cancer and airway injury) and their effects might be comparable to asbestos-induced carcinogenesis. Although fibrosis is a multi-origin disease, epithelial-mesenchymal transition (EMT) is recently recognized as an important pathway in cell transformation. It is known that MWCNT exposure induces EMT through the activation of the TGF-β/Smad signalling pathway thus promoting pulmonary fibrosis, but the molecular mechanisms involved are not fully understood. In the present work we propose a new mechanism involving a TGF-β-mediated signalling pathway. Methods: Human bronchial epithelial cells were incubated with two different MWCNT samples at various concentrations for up to 96 h and several markers of EMT were investigated. Quantitative real time PCR, western blot, immunofluorescent staining and gelatin zymographies were performed to detect the marker protein alterations. ELISA was performed to evaluate TGF-β production. Experiments with neutralizing anti-TGF-β antibody, specific inhibitors of GSK-3β and Akt and siRNA were carried out in order to confirm their involvement in MWCNT-induced EMT. In vivo experiments of pharyngeal aspiration in C57BL/6 mice were also performed. Data were analyzed by a one-way ANOVA with Tukey’s post-hoc test. Results: Fully characterized MWCNT (mean length < 5 μm) are able to induce EMT in an in vitro human model (BEAS-2B cells) after long-term incubation at sub-cytotoxic concentrations. MWCNT stimulate TGF-β secretion, Akt activation and GSK-3β inhibition, which induces nuclear accumulation of SNAIL-1 and its transcriptional activity, thus contributing to switch on the EMT program. Moreover, a significant increment of nuclear β-catenin - due to E-cadherin repression and following translocation to nucleus - likely reinforces signalling for EMT promotion. In vivo results supported the occurrence of pulmonary fibrosis following MWCNT exposure. (Continued on next page)
* Correspondence: [email protected] ˆDeceased 1 Department of Oncology, University of Turin, via Santena 5/bis, 10126 Turin, Italy 2 Interdepartmental Centre Scansetti for Studies on Asbestos and Other Toxic Particulates, University of Turin, Turin, Italy Full list of author information is available at the end of the article © 2016 Polimeni et al. Open Access This article is distr
Data Loading...
