YAP activates pancreatic stellate cells and enhances pancreatic fibrosis

Background: Pancreatic stellate cells (PSCs) foster the progression of pancreatic adenocarcinoma and chronic pancreatitis (CP) by producing a dense fibrotic stroma. However, the incomplete knowledge of PSCs biology hampers the exploration of antifibrotic therapies. Here, we explored the role of the Hippo pathway in the context of PSCs activation and experimental CP.Methods: CP model was created in rats with the tail vein injection of dibutyltin dichloride (DBTC). The expression of Yes-associated protein (YAP) in CP tissue was assessed. Primary and immortalized rats PSCs were treated with the YAP-inhibitor verteporfin. Furthermore, YAP siRNA was employed. Subsequently, DNA synthesis, cell survival, levels of alpha-smooth muscle actin (alpha-SMA) protein, presence of lipid droplets and PSCs gene expression were evaluated. Upstream regulators of YAP signaling were studied by reporter gene assays.Results: In DBTC-induced CP, pronounced expression of YAP in areas of tubular structures and periduc-tal fibrosis was observed. Verteporfin diminished DNA replication in PSCs in a dose-dependent fash-ion. Knockdown of YAP reduced cell proliferation. Primary cultures of PSCs were characterized by a de-crease of lipid droplets and increased synthesis of alpha-SMA protein. Both processes were not affected by verteporfin. At the non-cytotoxic concentration of 100 nmol/L, verteporfin significantly reduced mRNA levels of transforming growth factor -P1 (Tgf-P1 ) and Ccn family member 1 (Ccn1). YAP signaling was acti-vated by TGF-P1, but repressed by interferon-gamma.Conclusions: Activated YAP enhanced PSCs proliferation. The antifibrotic potential of Hippo pathway in-hibitors warrants further investigation.(c) 2022 First Affiliated Hospital, Zhejiang University School of Medicine in China. Published by Elsevier B.V. All rights reserved.