OBJECTIVETo explore the effect of polydatin on the growth of TGF-β₁induced humanalveolar epithelium A549 cells and the mechanism of polydatin for inhibiting the process of epithelial-mesenchymal transition (EMT).

METHODSA549 cells in vitro cultured were randomly divided into five groups, i.e., the blank group, the control group, the low dose polydatin group, the middle dose polydatin group, the high dose polydatin group. Common culture fluid was added in A549 cells of the blank group. Five ng/mLTGF-β₁contained culture fluid was added in A549 cells of the control group. 50, 100, and 150 μmol/mL of polydatin plus 5 ng/mL TGF-β₁contained culture fluid was added in A549 cells of low, middle, and high dosepolydatin groups, respectively. Morphological changes were observed and recorded at different time points. The optimal concentration of polydatin was determined by MTT method. Protein and mRNA expressions of E-cad epithelial cell marker) and Vimentin (mesenchymal cell marker) were detected by Western blot and Real-time PCR.

RESULTSUnder inverted phase contrast microscope, A549 cells turned from previous pebble shape to fusiform shape after intervened by polydatin and TGF-β1. The intercellular space was enlargedand the intercellular connection became loose. These phenomena were more obviously seen in the control group. A549 cells were more satiated in low, middle, and high dose polydatin groups than in the control group. The EMT inhibition was most obviously seen in the middle dose polydatin group at 48 h. Protein and mRNA expressions of E-cad showed an overall descending tendency after intervened by polydatin and TGF-β1 (P < 0.05). But compared with the control group, protein and mRNA expressions of E-cad were down-regulated in a lesser amplitude in each intervened group. Besides, the tendency was more obviously seen at 48 h than at 24 h. Protein and mRNA expressions of Vimentin showed an overall up-regulating tendency. But compared with the control group, protein and mRNA expressions of Vimentin were down-regulated in a lesser amplitude in each intervened group. Besides, the tendency was more obviously seen at 48 h than at 24 h (P < 0.05). CONCLUSIONS Polydatin could inhibit TGF-β1 induced EMT process of A549 cells time- and dose-dependently. It also played roles in inhibiting pulmonary fibrosis.