Role Of EMT-like Process In Activation Of Pancreatic Stellate Cells

Background: Pancreatic adenocarcinoma(PDAC) and chronic pancreatitis(CP) are all characterised by desmoplastic reaction with activated pancreatic stellate cells(PSCs), which play an important roles in these two disease. However, mechanisms of PSC activation are still poorly understood. We hypothesized that epithelial-mesenchymal transition(EMT) process might play a role during PSC activation.Objective: To clarify the role of EMT in the activation of pancreatic stellate cells. And explore potential mechanisms.Methods: Normal PSCs were isolated from Sprague-Dawley rat pancreas with enzyme digestion-gradient centrifuge method. Isolated PSCs were characterised by immunofluorescence and immunocytochemistry, both with positive markers and negative controls. To evaluate cell motility change after activation, PSCs after fresh isolation and late culture were compared in transwell migration assay and live cell imaging system. Expression of panel of EMT-related genes during the activation process were also assessed by q RT-PCR and Western blotting both at the m RNA and protein level.Results: One gram of rat pancreas tissue yielded 4-7 millions of PSCs. Activation of PSCsoccurred after around 48 hours of in vitro culture, as indicated by its morphological change to myofibroblastic shape and less in the number of lipid droplets. Enhancement in cell migration ability was observed in activated PSCs compared with the quiescent ones. After PSC activation, expression of epithelial markers, like E-cadherin, BMP7 and desmoplakin decreased, while expression of mesenchymal markers, including N-cadherin, vimentin, fibronectin1, collagen1α1 and S100A4 increased. In addition, EMT related transcription factors Snail and Slug were also up-regulated during that process.Conclusions: The concurrence of increased cell migration ability and alterations in EMT-related gene expression indicated that transition of quiescent PSCs to its activated form might involve EMT-like process. Therefore, this should be considered in identifying potential therapeutic targets to alleviate pancreatic fibrosis in diseases like CP and PDAC.