TGF-β1-miR-200a-PTEN induces epithelial-mesenchymal transition and fibrosis of pancreatic stellate cells.

Although the function of miR-200a has been discussed in many cancers and fibrotic diseases, its role in pancreatic fibrosis is still poorly understood. In this study, we for the first time confirm that miR-200a attenuates TGF-β1-induced pancreatic stellate cells activation and extracellular matrix formation. First, we find that TGF-β1 induces activation and extracellular matrix (ECM) formation in PSCs, and the effects are blocked by the inhibitor of PI3K (LY294002). Furthermore, we identify that miR-200a is down-regulated in TGF-β1-activated PSCs, and up-regulation of miR-200a inhibits PSCs activation induced by TGF-β1. Meanwhile, TGF-β1 inhibits the expression of the epithelial marker E-cadherin, and increases the expression of mesenchymal markers vimentin, and the expression of ECM proteins a-SMA and collagen I, while miR-200a mimic reversed the above effects in PSCs, indicating that miR-200a inhibits TGF-β1-induced activation and epithelial-mesenchymal transition (EMT). In addition, overexpression of miR-200a promotes the expression of PTEN and decreases the expression of matrix proteins and attenuates phosphorylation of Akt and mTOR. Taken together, our study uncovers a novel mechanism that miR-200a attenuates TGF-β1-induced pancreatic stellate cells activation and ECM formation through inhibiting PTEN /Akt/mTOR pathway.