N-Acetyl-cysteine protects A549 cells in paraquat-induced epithelial-mesenchymal transition

Objective To investigate the regulatory mechanism of Paraquat (PQ)-induced epithelial-mesenchymal transition (EMT) and the protective mechanism of N-acetyl-cysteine (NAC) in PQ-induced A549 cells by EMT markers (E-cadherin and α-smooth muscle actin). Methods EMT model was established by 30 μmol/L PQ-exposed A549 cells for 4 d. The application of 10 mmol/L NAC was incubated with A549 cells for 2 h in advance. Morphological changes of A549 cells were observed under light microscope. Western blot was used to detect the expression levels of TGF-β1, E-cadherin and α-smooth muscle actin. Results In PQ-induced EMT model, the PQ group showed typical morphological changes, and the cells changed from cobblestone-like epithelial appearance to spindle-shaped mesenchymal-like appearance compared to the control group. Western blotting showed that the protein levels of TGF-β1 and α-smooth muscle actin in the PQ group were significantly increased and the protein levels of E-cadherin were decreased in the PQ group (all P<0.05). NAC preincubation can effectively reverse the above changes caused by PQ exposure: the protein levels of E-cadherin and α-smooth muscle actin were significantly increased and decreased, respectively and morphological changes showed more cobblestone-like epithelial appearance. Conclusion Cell experiments showed that PQ exposure can cause EMT in epithelial cells, and NAC has a protective effect in this process. Thus, it may provide new ideas and strategies for the treatment of pulmonary fibrosis caused by PQ poisoning in clinical practice. Key words: Paraquat; N-Acetyl-cysteine; Transforming growth factor-β1; Epithelial-mesenchymal transition