TGF-β1/SMAD3-mediated Non-canonical Hedgehog Signaling Promotes Pancreatic Stellate Cell Activation and Fibrosis in Chronic Pancreatitis.

Excessive Hedgehog (Hh) signaling activity contributes to fibrosis in multiple organs. However, its role in pancreatic stellate cell (PSC) activation and fibrosis development during chronic pancreatitis (CP) remains elusive. We show that GLI2 is one of the top-ranked effectors in the pancreas of CP patients and is highly expressed in activated PSCs. PSC-specific deletion of Gli2, but not Smo, significantly reduces fibrosis and the severity of the mouse CP, indicating that GLI2 in PSCs can be driven by non-canonical fashion during CP. In culture-activated primary PSCs, early nuclear translocation and increased GLI2 expression are observed promptly following in vitro culture. Whereas GLI2 inhibition reduces PSC activation, SMO inhibition dose not consistently affect changes in GLI2 levels or PSC activation. TGF-β1 promotes GLI2 activation and expression, while these processes and resultant PSC activation are reversed by TGF-β1/SMAD3 inhibition. Altogether, these findings demonstrate the activation of the non-canonical Hh pathway in PSCs during CP and highlight that GLI2 represents a promising therapeutic target for CP.