Influence of JNK Signaling Pathway in the Epithelial-mesenchymal Transition Process of Human Alveolar Epithelial Cells Induced by TGF-β1 / 华中科技大学学报(医学版)

ABSTRACT

Objective To explore the role of JNK signaling pathway in epithelial mesenchymal transition (EMT)process of human alveolar epithelial cells A549 induced by TGF‐β1 in vitro.Methods Human alveolar epithelial cells (A549)cultured in vitro were divided randomly into three groupsnormal group ,TGF‐β1 group ( treated by TGF‐β1 with 10 ng/mL)and inhibitor group (treated by 10 ng/mL TGF‐β1 and 20 μmol/L Sp600125).Morphological observation on the cells was performed under light microscope after culturing in 3% serum medium for 72 h. The expression of E‐cadherin (E‐cad ,a epithelial cell marker) ,α‐smooth muscle actin (α‐SMA ,a mesenchymal cell marker)and Collagen fibers Ⅰ(ColⅠ ,a mesenchymal cell marker)were tested by RT‐PCR.The level of JNK phosphorylation (p‐JNK)was detected through Western blot.All experiments were repeated three times at least.Results The normal human alveolar epithelial cells (A549)cultured invitro were arranged closely like peb‐bles.E‐cad expressed at a certain level ,while the expression ofα‐SMA ,ColⅠand p‐JNK was weakly detected.In TGF‐β1 group , the cells were spindle‐shaped ,the expression of E‐cad was reduced ,while the expression ofα‐SMA ,ColⅠand p‐JNK was signifi‐cantly increased 72 h after treatment of TGF‐β1. However ,compared with TGF‐β1 group ,spindle‐shaped cells in the inhibitor group were recovered after 72 h being treated by TGF‐β1 and Sp600125 ,the expression of E‐cad was increased and the expres‐sion levels of α‐SMA ,ColⅠand p‐JNK were significantly decreased 72 h after treatment with TGF‐β1 and Sp600125 in inhibitor group. As compared with normal group ,the shape of the cells in inhibitor group was prolate ,and the expression of E‐cad ,α‐SMA ,ColⅠand p‐JNK was not significantly different.Conclusion JNK signaling pathway is related to the process of EMT of human alveolar epithelial cells induced by TGF‐β1. Sp600125 ,a special inhibitor of JNK ,could validly restrain the process.