Co-expression of YAP and TAZ associates with chromosomal instability in human cholangiocarcinoma.

Activation of the oncogene yes-associated protein (YAP) is frequently detected in intrahepatic cholangiocarcinoma (iCCA); however, the expression pattern and the functional impact of its paralogue WW domain-containing transcription regulator 1 (WWTR1; synonym: TAZ) are not well described in different CCA subtypes. Immunohistochemical analysis of YAP and TAZ in iCCA and extrahepatic CCA (eCCA) cohorts was performed. YAP/TAZ shuttling and their functional impact on CCA cell lines were investigated. Target genes expression after combined YAP/TAZ inhibition was analyzed. Immunohistochemical analysis of iCCA and eCCA revealed YAP or TAZ positivity in up to 49.2%; however, oncogene co-expression was less frequent (up to 23%). In contrast, both proteins were jointly detectable in most CCA cell lines and showed nuclear/cytoplasmic shuttling in a cell density-dependent manner. Next to the pro-proliferative function of YAP/TAZ, both transcriptional co-activators cooperated in the regulation of a gene signature that indicated the presence of chromosomal instability (CIN). A correlation between YAP and the CIN marker phospho-H2A histone family member X (pH2AX) was particularly observed in tissues from iCCA and distal CCA (dCCA). The presence of the CIN genes in about 25% of iCCA was statistically associated with worse prognosis. YAP and TAZ activation is not uncoupled from cell density in CCA cells and both factors cooperatively contribute to proliferation and expression of CIN-associated genes. The corresponding group of CCA patients is characterized by CIN and may benefit from YAP/TAZ-directed therapies.

Tóth M ，Wehling L ，Thiess L ，Rose F ，Schmitt J ，Weiler SME ，Sticht C ，De La Torre C ，Rausch M ，Albrecht T ，Grabe N ，Duwe L ，Andersen JB ，Köhler BC ，Springfeld C ，Mehrabi A ，Kulu Y ，Schirmacher P ，Roessler S ，Goeppert B ，Breuhahn K ... -  《BMC CANCER》

YAP and TAZ Heterogeneity in Primary Liver Cancer: An Analysis of Its Prognostic and Diagnostic Role.

Van Haele M ，Moya IM ，Karaman R ，Rens G ，Snoeck J ，Govaere O ，Nevens F ，Verslype C ，Topal B ，Monbaliu D ，Halder G ，Roskams T ... -  《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》

β-Catenin Sustains and Is Required for YES-associated Protein Oncogenic Activity in Cholangiocarcinoma.

YES-associated protein (YAP) aberrant activation is implicated in intrahepatic cholangiocarcinoma (iCCA). Transcriptional enhanced associate domain (TEAD)-mediated transcriptional regulation is the primary signaling event downstream of YAP. The role of Wnt/β-Catenin signaling in cholangiocarcinogenesis remains undetermined. Here, we investigated the possible molecular interplay between YAP and β-Catenin cascades in iCCA. Activated AKT (Myr-Akt) was coexpressed with YAP (YapS127A) or Tead2VP16 via hydrodynamic tail vein injection into mouse livers. Tumor growth was monitored, and liver tissues were collected and analyzed using histopathologic and molecular analysis. YAP, β-Catenin, and TEAD interaction in iCCAs was investigated through coimmunoprecipitation. Conditional Ctnnb1 knockout mice were used to determine β-Catenin function in murine iCCA models. RNA sequencing was performed to analyze the genes regulated by YAP and/or β-Catenin. Immunostaining of total and nonphosphorylated/activated β-Catenin staining was performed in mouse and human iCCAs. We discovered that TEAD factors are required for YAP-dependent iCCA development. However, transcriptional activation of TEADs did not fully recapitulate YAP's activities in promoting cholangiocarcinogenesis. Notably, β-Catenin physically interacted with YAP in human and mouse iCCA. Ctnnb1 ablation strongly suppressed human iCCA cell growth and Yap-dependent cholangiocarcinogenesis. Furthermore, RNA-sequencing analysis revealed that YAP/ transcriptional coactivator with PDZ-binding motif (TAZ) regulate a set of genes significantly overlapping with those controlled by β-Catenin. Importantly, activated/nonphosphorylated β-Catenin was detected in more than 80% of human iCCAs. YAP induces cholangiocarcinogenesis via TEAD-dependent transcriptional activation and interaction with β-Catenin. β-Catenin binds to YAP in iCCA and is required for YAP full transcriptional activity, revealing the functional crosstalk between YAP and β-Catenin pathways in cholangiocarcinogenesis.

Zhang Y ，Xu H ，Cui G ，Liang B ，Chen X ，Ko S ，Affo S ，Song X ，Liao Y ，Feng J ，Wang P ，Wang H ，Xu M ，Wang J ，Pes GM ，Ribback S ，Zeng Y ，Singhi A ，Schwabe RF ，Monga SP ，Evert M ，Tang L ，Calvisi DF ，Chen X ... -  《-》

The Hippo pathway effector TAZ induces intrahepatic cholangiocarcinoma in mice and is ubiquitously activated in the human disease.

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive primary liver tumor with increasing incidence worldwide, dismal prognosis, and few therapeutic options. Mounting evidence underlines the role of the Hippo pathway in this disease; however, the molecular mechanisms whereby the Hippo cascade contributes to cholangiocarcinogenesis remain poorly defined. We established novel iCCA mouse models via hydrodynamic transfection of an activated form of transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo pathway downstream effector, either alone or combined with the myristoylated AKT (myr-AKT) protooncogene, in the mouse liver. Hematoxylin and eosin staining, immunohistochemistry, electron microscopy, and quantitative real-time RT-PCR were applied to characterize the models. In addition, in vitro cell line studies were conducted to address the growth-promoting roles of TAZ and its paralog YAP. Overexpression of TAZ in the mouse liver triggered iCCA development with very low incidence and long latency. In contrast, co-expression of TAZ and myr-AKT dramatically increased tumor frequency and accelerated cancer formation in mice, with 100% iCCA incidence and high tumor burden by 10 weeks post hydrodynamic injection. AKT/TAZ tumors faithfully recapitulated many of the histomolecular features of human iCCA. At the molecular level, the development of the cholangiocellular lesions depended on the binding of TAZ to TEAD transcription factors. In addition, inhibition of the Notch pathway did not hamper carcinogenesis but suppressed the cholangiocellular phenotype of AKT/TAZ tumors. Also, knockdown of YAP, the TAZ paralog, delayed cholangiocarcinogenesis in AKT/TAZ mice without affecting the tumor phenotype. Furthermore, human preinvasive and invasive iCCAs and mixed hepatocellular carcinoma/iCCA displayed widespread TAZ activation and downregulation of the mechanisms protecting TAZ from proteolysis. Overall, the present data underscore the crucial role of TAZ in cholangiocarcinogenesis.

Cigliano A ，Zhang S ，Ribback S ，Steinmann S ，Sini M ，Ament CE ，Utpatel K ，Song X ，Wang J ，Pilo MG ，Berger F ，Wang H ，Tao J ，Li X ，Pes GM ，Mancarella S ，Giannelli G ，Dombrowski F ，Evert M ，Calvisi DF ，Chen X ，Evert K ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

WWC1 and NF2 Prevent the Development of Intrahepatic Cholangiocarcinoma by Regulating YAP/TAZ Activity through LATS in Mice.

Park J ，Kim JS ，Nahm JH ，Kim SK ，Lee DH ，Lim DS ... -  《-》