Activation of the Unfolded Protein Response (UPR) Is Associated with Cholangiocellular Injury, Fibrosis and Carcinogenesis in an Experimental Model of Fibropolycystic Liver Disease
Chaobo Chen 1 2 3 4, Hanghang Wu 1, Hui Ye 1 5, Agustín Tortajada 1 2, Sandra Rodríguez-Perales 6, Raúl Torres-Ruiz 6, August Vidal 7, Maria Isabel Peligros 8, Johanna Reissing 9, Tony Bruns 9, Mohamed Ramadan Mohamed 9, Kang Zheng 1, Amaia Lujambio 10 11 12 13, Maria J Iraburu 14, Leticia Colyn 15, Maria Ujue Latasa 15, María Arechederra 15 16 17, Maite G Fernández-Barrena 15 16 17, Carmen Berasain 15 16 17, Javier Vaquero 16 18 19, Rafael Bañares 16 18 19, Leonard J Nelson 20, Christian Trautwein 9, Roger J Davis 21, Eduardo Martinez-Naves 1 2, Yulia A Nevzorova 1 9 16 18, Alberto Villanueva 7, Matias A Avila 15 16 17, Francisco Javier Cubero 1 16 18
Fibropolycystic liver disease is characterized by hyperproliferation of the biliary epithelium and the formation of multiple dilated cysts, a process associated with unfolded protein response (UPR).
In the present study, we aimed to understand the mechanisms of cyst formation and UPR activation in hepatocytic c-Jun N-terminal kinase 1/2 (Jnk1/2) knockout mice. Floxed JNK1/2 (Jnkf/f) and Jnk∆hepa animals were sacrificed at different time points during progression of liver disease. Histological examination of specimens evidenced the presence of collagen fiber deposition, increased α-smooth muscle actin (αSMA), infiltration of CD45, CD11b and F4/80 cells and proinflammatory cytokines (Tnf, Tgfβ1) and liver injury (e.g., ALT, apoptosis and Ki67-positive cells) in Jnk∆hepa compared with Jnkf/f livers from 32 weeks of age. This was associated with activation of effectors of the UPR, including BiP/GRP78, CHOP and spliced XBP1. Tunicamycin (TM) challenge strongly induced ER stress and fibrosis in Jnk∆hepa animals compared with Jnkf/f littermates.
Finally, thioacetamide (TAA) administration to Jnk∆hepa mice induced UPR activation, peribiliary fibrosis, liver injury and markers of biliary proliferation and cholangiocarcinoma (CCA). Orthoallografts of DEN/CCl4-treated Jnk∆hepa liver tissue triggered malignant CCA. Altogether, these results suggest that activation of the UPR in conjunction with fibrogenesis might trigger hepatic cystogenesis and early stages of CCA.
Keywords: CM272; c-Jun N-terminal kinases (JNK); cholangiocarcinoma (CCA); endoplasmic reticulum (ER) stress; fibropolycystic liver disease; thioacetamide (TAA).