Fig. 3

SWCNTs impaired autophagic flux and triggered senescence of MLE-12 cells in vitro. A The cytotoxicity of SWCNTs (0, 5, 10, 25 and 50 μg/ml) at different time points (0, 6, 12, 24 and 48 h) was determined by the modified MTT assay. MLE-12 cells were treated with 10 μg/ml SWCNTs for 6, 12 and 24 h, and then the effects of SWCNTs on autophagy and senescence in MLE-12 cells were evaluated. B Scheme of workflow for time effects of SWCNTs on autophagy and senescence in MLE-12 cells and fibroblast-to-myofibroblast transdifferentiation (FMT) in lung fibroblasts in vitro. C–F Western Blotting analysis of Atg5, LC3BI, LC3BII and p62 protein expressions in MLE-12 cells (n = 3). G LC3B puncta in MLE-12 cells was observed by IF (200×). H–J Western Blotting analysis of p21 and p16 protein expressions in MLE-12 cells (n = 3). K SA-β-gal activity was determined by X-gal staining in MLE-12 cells (400×). L The number of SA-β-gal positive MLE-12 cells per field (n = 8). Contents of TGF-β (M) and PAI-1 (N) in the supernatants of culture medium quantified by ELISA (n = 5). *P < 0.05 vs CTRL group