YAP and the Hippo pathway in cholangiocarcinoma

CLK1 Activates YAP to Promote Intrahepatic Cholangiocarcinogenesis

Cdc2-like kinase 1 (CLK1) has dual-specificity kinase ability to phosphorylate tyrosine and serine/threonine protein residues. CLK1 regulates many physiologic processes and has been shown to contribute to multiple types of cancer. In this study, we investigated the functional role of CLK1 during intrahepatic cholangiocarcinoma (ICC) development. The expression of CLK1 was elevated in ICC tumors, and patients with high expression of CLK1 demonstrated poor prognosis. In hydrodynamically transfected mouse models, CLK1 alone was insufficient to induce ICC, whereas CLK1 cooperated with AKT (AKT/CLK1) to trigger ICC initiation. In addition, overexpression of CLK1 in ICC cells facilitated proliferation in vitro and tumor growth in vivo, whereas loss of CLK1 elicited the opposite effects. Moreover, RNA sequencing analysis indicated that high levels of CLK1 corresponded with activation of the Hippo-Yes-associated protein (YAP) signaling pathway. Consistently, AKT/CLK1 murine tumors displayed upregulation of YAP as well as its downstream targets. Furthermore, loss or pharmacologic inhibition of YAP in ICC cells inhibited CLK1-induced growth, and deletion of Yap completely retarded the induction of AKT/CLK1 tumors. Mechanistically, 4D label-free mass spectrometry and coimmunoprecipitation assays revealed WWC2 as a potential mediator of the CLK1-YAP cascade. Collectively, the current findings identify a critical role for CLK1 in promoting ICC development and indicate that inhibiting YAP might be an effective approach for perturbing CLK1-mediated tumorigenesis. Significance: CLK1 drives intrahepatic cholangiocarcinoma initiation and progression by increasing YAP activity, suggesting that targeting YAP could be a potential strategy for treating and preventing CLK1-driven intrahepatic cholangiocarcinoma.

YAP-TEAD inhibition is associated with upregulation of an androgen receptor mediated transcription program providing therapeutic escape

Cholangiocarcinoma (CCA) is a highly aggressive form of liver cancer and is an increasing cause of cancer-related death worldwide. Despite its increasing incidence globally and alarming mortality, treatment options for CCA have largely remained unchanged, stressing the importance of developing new effective therapies. YAP activation is common in CCA, and its major transcriptional signaling partners are the TEAD proteins. CA3 is a small-molecule YAP-TEAD disrupter discovered utilizing a TEAD reporter assay. Utilizing CCA, gastric cancer cell lines, and patient-derived xenograft models (PDX), we demonstrate that CA3 is effective in inducing cell death and delaying tumor growth in both FGFR2 fusion and wild-type models. CA3 was associated with on-target decreases in YAP-TEAD target gene expression, TEAD reporter activity, and overall TEAD levels. Hippo pathway signaling was not altered as there was no change in YAP phosphorylation status in the cells exposed to CA3. RNA sequencing of gastric cancer and CCA models demonstrated upregulation of an androgen receptor-mediated transcriptional program following exposure to CA3 in five unique models tested. Consistent with this upstream regulator analysis, CA3 exposure in CCA cells was associated with increased AR protein levels, and combinatorial therapy with CA3 and androgen receptor blockade was associated with increased cancer cell death. CA3 behaves functionally as a YAP-TEAD disrupter in the models tested and demonstrated therapeutic efficacy. Exposure to CA3 was associated with compensatory androgen receptor signaling and dual inhibition improved the therapeutic effect.

Targeting Hippo/YAP in intrahepatic cholangiocarcinoma: Promising molecules in cancer therapy

The tumorigenesis of intrahepatic cholangiocarcinoma (ICC) has been identified to be exceptionally involved in dysregulated Hippo/Yes-associated protein (YAP) signaling pathway (Hippo/YAP). Hippo/YAP functions as a master regulator engaged in a plethora of physiological and oncogenic processes as well. Therefore, the aberrant Hippo/YAP could serve as an Achilles' heel regarding the molecular therapeutic avenues for ICC patients. Herein, we comprehensively review the recent studies about the underlying mechanism of disrupted Hippo/YAP in ICC, how diagnostic values could be utilized upon the critical genes in this pathway, and what opportunities could be given upon this target pathway.

Identification of whole-genome mutations and structural variations of bile cell-free DNA in cholangiocarcinoma

Bile cell-free DNA (cfDNA) has been reported as a promising liquid biopsy tool for cholangiocarcinoma (CCA), however, the whole-genome mutation landscape and structural variants (SVs) of bile cfDNA remains unknown. Here we performed whole-genome sequencing on bile cfDNA and analyzed the correlation between mutation characteristics of bile cfDNA and clinical prognosis. TP53 and KRAS were the most frequently mutated genes, and the RTK/RAS, homologous recombination (HR), and HIPPO were top three pathways containing most gene mutations. Ten overlapping putative driver genes were found in bile cfDNA and tumor tissue. SVs such as chromothripsis and kataegis were identified. Moreover, the hazard ratio of HR pathway mutations were 15.77 (95% CI: 1.571-158.4), patients with HR pathway mutations in bile cfDNA exhibited poorer overall survival (P = 0.0049). Our study suggests that bile cfDNA contains genome mutations and SVs, and HR pathway mutations in bile cfDNA can predict poor outcomes of CCA patients.

Regulation of Hippo-YAP signaling axis by Isoalantolactone suppresses tumor progression in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a devastating malignancy characterized by aggressive tumor growth and limited treatment options. Dysregulation of the Hippo signaling pathway and its downstream effector, Yes-associated protein (YAP), has been implicated in CCA development and progression. In this study, we investigated the effects of Isoalantolactone (IALT) on CCA cells to elucidate its effect on YAP activity and its potential clinical significance. Our findings demonstrate that IALT exerts cytotoxic effects, induces apoptosis, and modulates YAP signaling in SNU478 cells. We further confirmed the involvement of the canonical Hippo pathway by generating LATS1/LATS2 knockout cells, highlighting the dependence of IALT-mediated apoptosis and YAP phosphorylation on the Hippo-LATS signaling axis. In addition, IALT suppressed cell growth and migration, partially dependent on YAP-TEAD activity. These results provide insights into the therapeutic potential of targeting YAP in CCA and provide a rationale for developing of YAP-targeted therapies for this challenging malignancy.

Syngeneic murine models with distinct immune microenvironments represent subsets of human intrahepatic cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a poorly immunogenic malignancy associated with limited survival. Syngeneic immunocompetent mouse models of CCA are an essential tool to elucidate the tumor immune microenvironment (TIME), understand mechanisms of tumor immune evasion, and test novel immunotherapeutic strategies. The scope of this study was to develop and characterize immunocompetent CCA models with distinct genetic drivers, and correlate tumor genomics, immunobiology, and therapeutic response.

METHODS

A multifaceted approach including scRNA-seq, CITE-seq, whole exome and bulk RNA sequencing was employed. FDA-approved PD-1/PD-L1 antibodies were tested in humanized PD-1/PD-L1 mice (HuPD-H1).

RESULTS

A genetic mouse model of intrahepatic CCA (iCCA) driven by intrabiliary transduction of Fbxw7ΔF/Akt that mimics human iCCA was generated. From the Fbxw7ΔF/Akt tumors, a murine cell line (FAC) and syngeneic model with genetic and phenotypic characteristics of human iCCA were developed. Established SB1 (YAPS127A/Akt) and KPPC (KrasG12Dp53L/L) models were compared to the FAC model. Although the models had transcriptomic similarities, they had substantial differences as well. Mutation patterns of FAC, SB1, and KPPC cells matched different mutational signatures in Western and Japanese CCA patient cohorts. KPPC tumors had a high tumor mutation burden. FAC tumors had a T cell-infiltrated TIME, while SB1 tumors had a preponderance of suppressive myeloid cells. FAC, SB1, and KPPC tumors matched different immune signatures in human iCCA cohorts. Moreover, FAC, SB1, and KPPC tumor-bearing HuPD-H1 mice displayed differential responses to nivolumab or durvalumab.

CONCLUSIONS

Syngeneic iCCA models display a correlation between tumor genotype and TIME phenotype, with differential responses to FDA-approved immunotherapies. This study underscores the importance of leveraging multiple preclinical models to understand responses to immunotherapy in different genetic subsets of human CCA.

IMPACT AND IMPLICATIONS

Understanding the relationship between tumor genotype and the phenotype of the immune microenvironment is an unmet need in cholangiocarcinoma (CCA). Herein, we use syngeneic murine models of intrahepatic CCA with different genetic drivers to demonstrate a correlation between tumor genotype and immune microenvironment phenotype in murine models, which is associated with differential responses to FDA-approved immunotherapies. This information will help guide other preclinical studies. Additionally, it emphasizes that immune checkpoint inhibition in patients with CCA is not a "one-size-fits-all" approach. Our observations suggest that, as for targeted therapies, patients should be stratified and selected for treatment according to their tumor genetics.

Interplay between YAP/TAZ and metabolic dysfunction-associated steatotic liver disease progression

Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming an increasingly pressing global health challenge, with increasing mortality rates showing an upward trend. Two million deaths occur annually from cirrhosis and liver cancer together each year. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), key effectors of the Hippo signaling pathway, critically regulate tissue homeostasis and disease progression in the liver. While initial studies have shown that YAP expression is normally restricted to cholangiocytes in healthy livers, the activation of YAP/TAZ is observed in other hepatic cells during chronic liver disease. The disease-driven dysregulation of YAP/TAZ appears to be a critical element in the MASLD progression, contributing to hepatocyte dysfunction, inflammation, and fibrosis. In this study, we focused on the complex roles of YAP/TAZ in MASLD and explored how the YAP/TAZ dysregulation of YAP/TAZ drives steatosis, inflammation, fibrosis, and cirrhosis. Finally, the cell-type-specific functions of YAP/TAZ in different types of hepatic cells, such as hepatocytes, hepatic stellate cells, hepatic macrophages, and biliary epithelial cells are discussed, highlighting the multifaceted impact of YAP/TAZ on liver physiology and pathology.

Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

Cancer has become a burgeoning global healthcare concern marked by its exponential growth and significant economic ramifications. Though advancements in the treatment modalities have increased the overall survival and quality of life, there are no definite treatments for the advanced stages of this malady. Hence, understanding the diseases etiologies and the underlying molecular complexities, will usher in the development of innovative therapeutics. Recently, YAP/TAZ transcriptional regulation has been of immense interest due to their role in development, tissue homeostasis and oncogenic transformations. YAP/TAZ axis functions as coactivators within the Hippo signaling cascade, exerting pivotal influence on processes such as proliferation, regeneration, development, and tissue renewal. In cancer, YAP is overexpressed in multiple tumor types and is associated with cancer stem cell attributes, chemoresistance, and metastasis. Activation of YAP/TAZ mirrors the cellular "social" behavior, encompassing factors such as cell adhesion and the mechanical signals transmitted to the cell from tissue structure and the surrounding extracellular matrix. Therefore, it presents a significant vulnerability in the clogs of tumors that could provide a wide window of therapeutic effectiveness. Natural compounds have been utilized extensively as successful interventions in the management of diverse chronic illnesses, including cancer. Owing to their capacity to influence multiple genes and pathways, natural compounds exhibit significant potential either as adjuvant therapy or in combination with conventional treatment options. In this review, we delineate the signaling nexus of YAP/TAZ axis, and present natural compounds as an alternate strategy to target cancer.

Research trends of targeted therapy for cholangiocarcinoma from 2003 to 2022: a bibliometric and visual analysis

In the past 20 years, targeted therapy for cholangiocarcinoma has attracted certain attention. There is a significant upward in papers focusing on this field. In this study, we used bibliometric and visual methods to explore the current status and future directions in cholangiocarcinoma-targeted therapy research. A total of 1057 papers published in English from 2003 to 2022 were extracted from the Web of Science Core Collection SCI-expanded database. Furthermore, Citespace, Vosviewer, and Excel 2016 were utilized to conduct bibliometric and visual analysis. The volume of annual publications has steadily increased over the past two decades. The USA has published the largest number of publications, and the Mayo Clinic acted as the dominant institution. Cancers, Frontiers in Oncology, and Hepatology were the prolific resources in this research field. Moreover, the co-cited reference analysis uncovered the landmark paper in this field. With regard to research hotspots and frontiers, the burst keywords analysis showed that growth factor receptors and pathogenesis might become the hot topics of future research. To sum up, our study displays the current research status and future directions in the targeted therapy for cholangiocarcinoma. More comprehensive and in-depth investigations should focus on critical genetic mutations and their molecular mechanisms to prompt the molecular-targeted therapy.

An update on the role of Hippo signaling pathway in ischemia-associated central nervous system diseases

The most frequent reason of morbidity and mortality in the world, cerebral ischemia sets off a chain of molecular and cellular pathologies that associated with some central nervous system (CNS) disorders mainly including ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy and other CNS diseases. In recent times, despite significant advancements in the treatment of the pathological processes underlying various neurological illnesses, effective therapeutic approaches that are specifically targeted to minimizing the damage of such diseases remain absent. Hippo signaling pathway, characterized by enzyme linked reactions between MSTI/2, LAST1/2, and YAP or TAZ proteins, controls cell division, survival, and differentiation, as well as being engaged in a variety of biological activities, such as the development and transformation of the nervous system. Recently, accumulating studies demonstrated that Hippo pathway takes part in the processes of ischemic stroke, AD, PD, etc., including but not limited to oxidative stress, inflammatory response, blood-brain barrier damage, mitochondrial disorders, and neural cells death. Thus, it's crucial to understand the molecular basis of the Hippo signaling pathway for determining potential new therapeutic targets against ischemia-associated CNS diseases. Here, we discuss latest advances in the deciphering of the Hippo signaling pathway and highlight the therapeutic potential of targeting the pathway in treating ischemia-associated CNS diseases.

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

BACKGROUND & AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

YY1-induced DLEU1/miR-149-5p Promotes Malignant Biological Behavior of Cholangiocarcinoma through Upregulating YAP1/TEAD2/SOX2

Cholangiocarcinoma is an extremely malignant cancer with poor prognosis. Finding efficient diagnosis and treatment is the indispensable way to improve the prognosis of CCA patients. Therefore, exploring molecular abnormalities in CCA development is urgently needed. DLEU1 is a potential tumor-related lncRNA and abnormally expressed in multiple cancers. In this study, TCGA data analysis showed upregulation of DLEU1 expression in CCA. Furthermore, we confirmed that DLEU1 expression was increased in CCA tissues and cells compared with corresponding controls. Upregulated DLEU1 was related to poor clinicopathological characteristics. Functionally, silencing DLEU1 inhibited CCA proliferation, invasion, stemness maintenance and chemo-resistance, whereas amplifying DLEU1 promoted malignant biological behavior of CCA cells. Mechanistically, DLEU1 expression was transcriptionally facilitated by transcription factor YY1. Moreover, DLEU1 promoted oncogene YAP1 expression by functioning as a sponge to competitively bind to miR-149-5p. YAP1 promoted CCA proliferation, invasion and stemness maintenance, whereas miR-149-5p inhibited malignant biological behavior of CCA. Rescue experiments confirmed that the cancer-promoting effect of DLEU1 was saved by interfering miR-149-5p or YAP1. Furthermore, YAP1 promoted tumor stemness maintenance partly by acting as a transcriptional coactivator to promote TEAD2-induced SOX2 expression. These findings indicated that YY1-induced DLEU1 played a crucial role in CCA progression via miR-149-5p/YAP1/TEAD2/SOX2 axis.

m5 C and m6 A modification of long noncoding NKILA accelerates cholangiocarcinoma progression via the miR-582-3p-YAP1 axis

Cholangiocarcinoma (CCA) is a severe malignancy originating from the bile duct and the second most common primary liver cancer. NF-kappa B interacting lncRNA (NKILA) is a functional lncRNA, which play important role in human cancers. However, the role and underlying mechanism of NKILA in CCA remains largely unknown. Here, our study demonstrated that NKILA was significantly upregulated in CCA tissues and cells. Overexpression of NKILA is associated with advanced TNM stage, lymph node and distant metastasis, and also indicated poor prognosis in CCA patients. Functionally, NKILA facilitated CCA growth and metastasis in vitro and in vivo. The 5-methylcytosine (m⁵ C) methyltransferase NSUN2 interacts with NKILA, increasing its m⁵ C level and promoting its interaction with YBX1. Moreover, NKILA physically interacted with and suppressed miR-582-3p, which was regulated by METTL3-mediated N⁶ -methyladenosine (m⁶ A) modification. Finally, we showed that YAP1 was a target of NKILA via miR-582-3p and NKILA functioned partially via YAP1 in CCA. Taken together, our findings indicate a novel regulatory mechanism of NKILA for promoting CCA progression and that NKILA may be a promising target for CCA treatment.

Inflammatory pathways and cholangiocarcinoma risk mechanisms and prevention

Cholangiocarcinoma (CCA), a neoplasm burdened by a poor prognosis and currently lacking adequate therapeutic treatments, can originate at different levels of the biliary tree, in the intrahepatic, hilar, or extrahepatic area. The main risk factors for the development of CCA are the presence of chronic cholangiopathies of various etiology. To date, the most studied prodromal diseases of CCA are primary sclerosing cholangitis, Caroli's disease and fluke infestations, but other conditions, such as metabolic syndrome, nonalcoholic fatty liver disease and obesity, are emerging as associated with an increased risk of CCA development. In this review, we focused on the analysis of the pro-inflammatory mechanisms that induce the development of CCA and on the role of cells of the immune response in cholangiocarcinogenesis. In very recent times, these cellular mechanisms have been the subject of emerging studies aimed at verifying how the modulation of the inflammatory and immunological responses can have a therapeutic significance and how these can be used as therapeutic targets.

YAP1 activation and Hippo pathway signaling in the pathogenesis and treatment of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA), the second most common primary liver cancer, is a highly lethal epithelial cell malignancy exhibiting features of cholangiocyte differentiation. iCCAs can potentially develop from multiple cell types of origin within liver, including immature or mature cholangiocytes, hepatic stem cells/progenitor cells, and from transdifferentiation of hepatocytes. Understanding the molecular mechanisms and genetic drivers that diversely drive specific cell lineage pathways leading to iCCA has important biological and clinical implications. In this context, activation of the YAP1-TEAD dependent transcription, driven by Hippo-dependent or -independent diverse mechanisms that lead to the stabilization of YAP1 is crucially important to biliary fate commitment in hepatobiliary cancer. In preclinical models, YAP1 activation in hepatocytes or cholangiocytes is sufficient to drive their malignant transformation into iCCA. Moreover, nuclear YAP1/TAZ is highly prevalent in human iCCA irrespective of the varied etiology, and significantly correlates with poor prognosis in iCCA patients. Based on the ubiquitous expression and diverse physiologic roles for YAP1/TAZ in the liver, recent studies have further revealed distinct functions of active YAP1/TAZ in regulating tumor metabolism, as well as the tumor immune microenvironment. In the current review, we discuss our current understanding of the various roles of the Hippo-YAP1 signaling in iCCA pathogenesis, with a specific focus on the roles played by the Hippo-YAP1 pathway in modulating biliary commitment and oncogenicity, iCCA metabolism, and immune microenvironment. We also discuss the therapeutic potential of targeting the YAP1/TAZ-TEAD transcriptional machinery in iCCA, its current limitations, and what future studies are needed to facilitate clinical translation.

SAHA induce hippo pathway in CCA cells without increasing cell proliferation

BACKGROUND

Cholangiocarcinoma is a malignant tumor originating from bile duct epithelial cells. Since tumor metastasis is associated with poor prognosis and short-term survival of patients, there is an urgent need for alternative therapeutic approaches for CCA. Because of that reason, we aimed to investigate effect of SAHA which is known as HDAC inhibitor on extrahepatic cholangiocarcinoma cell line (TFK-1).

METHODS

Cell cycle was measured by Muse Cell Analyzer. YAP, TAZ, TGF-β protein levels were determined by western-blotting method. TEAD (1-3), TIMP2 and TIMP3 genes level were determined by real-time PCR analysis.

RESULTS

We have seen the positive effects of SAHA on the TFK-1 cell line as it reduces cell viability and arresting cells in the G0/G1 phase. We also observed the negative effects of SAHA, as it increases the expression levels of YAP, TAZ, TGF-β protein and TEAD (1-3) gene. We also found that SAHA reduced the expression levels of TIMP2 and TIMP3 in TFK-1 cells, but was not statistically significant.

CONCLUSIONS

Although observing its antiproliferative effects, these negative effects may be related to the cells being resistant to the drug or the remaining cells having a more aggressive phenotype. Therefore, we think that caution should be exercised in the use of this drug for CCA treatment.

R-2HG downregulates ERα to inhibit cholangiocarcinoma via the FTO/m6A-methylated ERα/miR16-5p/YAP1 signal pathway

Isocitrate dehydrogenase (IDH) mutations increase (R)-2-hydroxyglutarate (R-2HG) production; however, functional mechanisms of R-2HG in regulating cholangiocarcinoma (CCA) development remain to be further investigated. We first applied the CRISPR-Cas9 gene-editing system to create IDH1R132H-mutated CCA cells. Interestingly, our data showed that R-2HG could function through downregulating estrogen receptor alpha (ERα) and Yes-associated protein 1 (YAP1) pathways to decrease CCA growth. Detailed mechanistic studies revealed that R-2HG could target and degrade the fat mass and obesity-associated protein (FTO), the first identified mRNA demethylase. This reduced FTO can increase the N⁶-methyladenosine (m6A) to methylate the mRNA of ERα, and consequently decrease protein translation of the ERα. Further mechanistic studies revealed that ERα could transcriptionally suppress miR-16-5p expression, which could then increase YAP1 expression due to the reduced miR-16-5p binding to the 3′ UTR of YAP1. Furthermore, data from the pre-clinical animal model with implantation of IDH1R132H QBC939 cells demonstrated that R-2HG generated by the IDH1 mutation could downregulate ERα and YAP1 to suppress CCA tumor growth. Taken together, our new findings suggested that IDH1 mutation-induced R-2HG could suppress CCA growth via regulating the FTO/m6A-methylated ERα/miR16-5p/YAP1 signaling pathway. Upregulating R-2HG or downregulating the ERα signal by short hairpin RNA ERα (shERα) or antiestrogen could be effective strategies to inhibit CCA.

Deubiquitinase JOSD2 stabilizes YAP/TAZ to promote cholangiocarcinoma progression

Cholangiocarcinoma (CCA) has emerged as an intractable cancer with scanty therapeutic regimens. The aberrant activation of Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are reported to be common in CCA patients. However, the underpinning mechanism remains poorly understood. Deubiquitinase (DUB) is regarded as a main orchestrator in maintaining protein homeostasis. Here, we identified Josephin domain-containing protein 2 (JOSD2) as an essential DUB of YAP/TAZ that sustained the protein level through cleavage of polyubiquitin chains in a deubiquitinase activity-dependent manner. The depletion of JOSD2 promoted YAP/TAZ proteasomal degradation and significantly impeded CCA proliferation in vitro and in vivo. Further analysis has highlighted the positive correlation between JOSD2 and YAP abundance in CCA patient samples. Collectively, this study uncovers the regulatory effects of JOSD2 on YAP/TAZ protein stabilities and profiles its contribution in CCA malignant progression, which may provide a potential intervention target for YAP/TAZ-related CCA patients.

Long noncoding RNA SNHG3 promotes malignant phenotypes in cervical cancer cells via association with YAP1

Long non-coding RNA (LncRNA) Small Nucleolar RNA Host Gene 3 (SNHG3) is involved in the occurrence and development of various cancers. However, the exact function and mechanism of SNHG3 in cervical cancer (CC) are still unclear. In this context, we identified a significant increase of SNHG3 expression in CC tissues. Upregulation of SNHG3 expression was associated with advanced FIGO stage and metastasis, and indicated poor overall survival of the CC patients. Functionally, SNHG3 enhanced the proliferation, migration and invasion of CC cells in vitro, and facilitated CC growth in vivo. Further investigation uncovered that SNHG3 interacted with oncoprotein YAP1, thus suppressing its degradation. Additionally, SNHG3 modulated the transcription of several target genes of YAP1. The oncogenic role of SNHG3 was partially attributable to YAP1. Taken together, our research revealed the prognostic and functional roles for SNHG3 in CC, suggesting that SNHG3 could serve as a biomarker for prognosis and a therapeutic target for CC.

Focal adhesion kinase (FAK) promotes cholangiocarcinoma development and progression via YAP activation

BACKGROUND & AIMS

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is upregulated in many tumor types and is a promising target for cancer therapy. Herein, we elucidated the functional role of FAK in intrahepatic cholangiocarcinoma (iCCA) development and progression.

METHODS

Expression levels and activation status of FAK were determined in human iCCA samples. The functional contribution of FAK to Akt/YAP murine iCCA initiation and progression was investigated using conditional Fak knockout mice and constitutive Cre or inducible Cre mice, respectively. The oncogenic potential of FAK was further examined via overexpression of FAK in mice. In vitro cell line studies and in vivo drug treatment were applied to address the therapeutic potential of targeting FAK for iCCA treatment.

RESULTS

FAK was ubiquitously upregulated and activated in iCCA lesions. Ablation of FAK strongly delayed Akt/YAP-driven mouse iCCA initiation. FAK overexpression synergized with activated AKT to promote iCCA development and accelerated Akt/Jag1-driven cholangiocarcinogenesis. Mechanistically, FAK was required for YAP(Y357) phosphorylation, supporting the role of FAK as a central YAP regulator in iCCA. Significantly, ablation of FAK after Akt/YAP-dependent iCCA formation strongly suppressed tumor progression in mice. Furthermore, a remarkable iCCA growth reduction was achieved when a FAK inhibitor and palbociclib, a CDK4/6 inhibitor, were administered simultaneously in human iCCA cell lines and Akt/YAP mice.

CONCLUSIONS

FAK activation contributes to the initiation and progression of iCCA by inducing the YAP proto-oncogene. Targeting FAK, either alone or in combination with anti-CDK4/6 inhibitors, may be an effective strategy for iCCA treatment.

LAY SUMMARY

We found that the protein FAK (focal adhesion kinase) is upregulated and activated in human and mouse intrahepatic cholangiocarcinoma samples. FAK promotes intrahepatic cholangiocarcinoma development, whereas deletion of FAK strongly suppresses its initiation and progression. Combined FAK and CDK4/6 inhibitor treatment had a strong anti-cancer effect in in vitro and in vivo models. This combination therapy might represent a valuable and novel treatment against human intrahepatic cholangiocarcinoma.

HOXB13 suppresses proliferation, migration and invasion, and promotes apoptosis of gastric cancer cells through transcriptional activation of VGLL4 to inhibit the involvement of TEAD4 in the Hippo signaling pathway

Gastric cancer (GC) is one of the most common types of malignancy worldwide and is accompanied by both high mortality and morbidity rates. Homeobox B13 (HOXB13) has been reported to act as a tumor suppressor gene in multiple types of human cancer. The present study aimed to investigate the effects and potential underlying molecular mechanisms of HOXB13 in the progression of GC. The expression of HOXB13 in GC cells was first examined using the Cancer Cell Line Encyclopedia database and subsequently validated in a number of GC cell lines. Following HOXB13 overexpression (Ov-HOXB13), HGC-27 cell proliferation was evaluated by colony formation and Cell Counting Kit-8 assays. Wound healing and Matrigel assays were used to determine the migratory and invasive abilities, respectively. Additionally, cell apoptosis was assessed using TUNEL staining, and the expression of apoptosis-related proteins was detected by western blot analysis. Subsequently, TEA domain transcription factor 4 (TEAD4) was overexpressed to evaluate the effects on HGC-27 cell proliferation, migration, invasion and apoptosis following co-transfection with Ov-HOXB13. The potential binding sites of HOXB13 on the vestigial-like family member 4 (VGLL4) promoter were verified using chromatin immunoprecipitation and dual luciferase reporter assays. Moreover, the expression levels of proteins involved in the Hippo signaling pathway were analyzed using western blotting. The results revealed that the expression of HOXB13 was notably lower in GC cells compared with normal gastric cells. The overexpression of HOXB13 significantly inhibited the proliferation, migration and invasion, but promoted the apoptosis of HGC-27 cells. Moreover, Ov-HOXB13 downregulated TEAD4 expression. Notably, Ov-TEAD4 transfection partially reversed the effects of Ov-HOXB13 on the cellular behaviors of HGC-27 cells. HOXB13 was also confirmed to bind with the VGLL4 promoter. The knockdown of VGLL4 restored the inhibitory effects of Ov-HOXB13 on the expression levels of VGLL4 and Hippo pathway signaling proteins. In conclusion, the findings of the present study suggested that Ov-HOXB13 may suppress the proliferation, migration and invasion, and promote the apoptosis of GC cells through the transcriptional activation of VGLL4 to inhibit the involvement of TEAD4 in the Hippo signaling pathway. These results may provide novel and potent targets for the treatment of GC.

The Application Progress of Patient-Derived Tumor Xenograft Models After Cholangiocarcinoma Surgeries

Surgical treatment is the only possible cure for cholangiocarcinoma (CCA) at present. However, the high recurrence rate of postoperative CCA leads to a very poor prognosis for patients, effective postoperative chemotherapy is hence the key to preventing the recurrence of CCA. The sensitivity of CCA to cytotoxic chemotherapy drugs and targeted drugs varies from person to person, and therefore, the screening of sensitive drugs has become an important topic after CCA surgeries. Patient-Derived tumor Xenograft models (PDX) can stably retain the genetic and pathological characteristics of primary tumors, and better simulate the tumor microenvironment of CCA. The model is also of great significance in screening therapeutic targeted drugs after CCA, analyzing predictive biomarkers, and improving signal pathways in prognosis and basic research. This paper will review the current established methods and applications of the patient-derived tumor xenograft model of cholangiocarcinoma, aiming to provide new ideas for basic research and individualized treatment of cholangiocarcinoma after surgery.

Downregulation of tumor-derived exosomal miR-34c induces cancer-associated fibroblast activation to promote cholangiocarcinoma progress

Background

This study aimed to investigate the exact regulatory mechanisms of exosomal miR-34c in mediating communication between cholangiocarcinoma cells and fibroblasts.

Methods

Exosomes were isolated from HuCCT-1 and HIBEC cells using differential ultracentrifugation and identified by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) method. Real-time quantitative PCR (qRT-PCR) and western blotting analyses were performed to assess the levels of pro-inflammatory factors, and fibroblast-related proteins and Wnt-linked signaling pathway proteins, respectively. Exosome-tracking was performed with confocal microscopy. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and Transwell assays were used to measure cell proliferation and migration, respectively. Further, the oncogenicity of cholangiocarcinoma cells was analyzed in nude mice transplanted tumor model.

Results

The analysis suggested that the expression of miR-34c was decreased in exosomes from HuCCT-1 cells. Moreover, miR-34c in exosomes mediated fibroblast activation by directly targeting WNT1. Additionally, cancer-associated fibroblasts (CAFs) activated by downregulation of exosomal miR-34c promoted cholangiocarcinoma progression.

Conclusions

Thus, miR-34c in exosomes was found to be a key player in regulating intercellular communication between tumor cells and fibroblasts.

Piezo 1 activation facilitates cholangiocarcinoma metastasis via Hippo/YAP signaling axis

Tumor metastasis is one of the major factors for the high mortality in cholangiocarcinoma (CCA), but its underlying mechanisms are not fully understood. Here, we report that Piezo-type mechanosensitive ion channel component 1 (Piezo 1) is detected to be significantly upregulated in CCA tissues, which is linked to a poor prognosis in patients, suggesting that Piezo 1 may act in a pro-metastatic role in CCA development. Piezo 1 is activated through 20% simulated physiological stretch, and deleting Piezo 1 impedes epithelial-to-mesenchymal transition (EMT) of CCA cells, as well as impairing their metastatic capacity in vitro and in vivo. Mechanistically, the activation of Piezo 1 results in large amounts of Yes-associated protein 1 (YAP) translocated into the nucleus from the cytoplasm, and thus the motility of CCA cells is significantly increased. These findings indicate that mechanical stimulation induces Piezo 1 activation, which might be involved in CCA metastasis via the Hippo/YAP signaling axis. Therefore, Piezo 1 and its downstream effectors may be a novel therapeutic target for CCA treatment.

KLF4 initiates sustained YAP activation to promote renal fibrosis in mice after ischemia-reperfusion kidney injury

Acute renal injury (AKI) causes a long-term risk for progressing into chronic kidney disease (CKD) and interstitial fibrosis. Yes-associated protein (YAP), a key transcriptional cofactor in Hippo signaling pathway, shuttles between the cytoplasm and nucleus, which is required for the renal tubular epithelial cells repair in the acute phase of AKI. In this study we investigated the role of YAP during ischemia-reperfusion (IR)-induced AKI to CKD. Mice were subjected to left kidney IR followed by removal of the right kidney on the day before tissue harvests. Mouse shRNA expression adenovirus (Ad-shYAP or Ad-shKLF4) and mouse KLF4 expression adenovirus (Ad-KLF4) were delivered to mice by intrarenal injection on D7 after IR. We showed that the expression and nucleus distribution of YAP were persistently increased until the end of experiment (D21 after IR). The sustained activation of YAP in post-acute phase of AKI was accompanied by renal dysfunction and interstitial fibrosis. Knockdown of YAP significantly attenuated IR-induced renal dysfunction and decreased the expression of fibrogenic factors TGF-β and CTGF in the kidney. We showed that the expression of the transcription factor KLF4, lined on the upstream of YAP, was also persistently increased. Knockdown on KLF4 attenuated YAP increase and nuclear translocation as well as renal functional deterioration and interstitial fibrosis in IR mice, whereas KLF4 overexpression caused opposite effects. KLF4 increased the expression of ITCH, and ITCH facilitated YAP nuclear translocation via degrading LATS1. Furthermore, we demonstrated in primary cultured renal tubular cells that KLF4 bound to the promoter region of YAP and positively regulates YAP expression. In biopsy sample from CKD patients, we also observed increased expression and nuclear distribution of YAP. In conclusion, the activation of YAP in the post-acute phase of AKI is implicated in renal functional deterioration and fibrosis although it exhibits beneficial effect in acute phase. Reprogramming factor KLF4 is responsible for the persistent activation of YAP. Blocking the activation of KLF4-YAP pathway might be a way to prevent the transition of AKI into CKD.

Targeted therapies for extrahepatic cholangiocarcinoma: preclinical and clinical development and prospects for the clinic

Introduction: Until recently, cholangiocarcinoma (CCA) was a largely overlooked disease, and among CCAs, extrahepatic CCA (eCCA) was even more neglected. Despite the growing impact of molecularly targeted therapies and immunotherapy, prognosis of eCCA is dismal. Therefore, unraveling the complex molecular landscape of eCCA has become an urgent need. Deep phenotyping studies have revealed that eCCA is a heterogeneous tumor, harboring specific alterations categorizable into four classes, 'Mesenchymal', 'Proliferation', 'Immune', 'Metabolic'. Molecular alterations convey the activation of several pro-oncogenic pathways, where either actionable drivers or outcome predictors can be identified.Areas covered: We offer insights on perturbed pathways, molecular profiling, and actionable targets in eCCA and present a perspective on the potential stepping-stones to future progress. A systematic literature search in PubMed/ClinicalTrials.gov websites was performed by authors from different disciplines according to their specific topic knowledge to identify the newest and most relevant advances in precision medicine of eCCA.Expert opinion: eCCA is a distinct entity with unique features in terms of molecular classes, oncogenic drivers, and tumor microenvironment. Since more prevalent mutations are currently undruggable, and immunotherapy can be offered only to a minority of patients, international collaborations are instrumental to improve the understanding of the molecular underpins of this disease.

Pathogenesis of Cholangiocarcinoma

Cholangiocarcinoma (CCA) encompasses a group of malignancies that can arise at any point in the biliary tree. Although considered a rare cancer, the incidence of CCA is increasing globally. The silent and asymptomatic nature of these tumors, particularly in their early stages, in combination with their high aggressiveness, intra- and intertumor heterogeneity, and chemoresistance, significantly compromises the efficacy of current therapeutic options, contributing to a dismal prognosis. During the last few years, increasing efforts have been made to unveil the etiologies and pathogenesis of these tumors and to develop more effective therapies. In this review, we summarize current findings in the field of CCA, mainly focusing on the mechanisms of pathogenesis, cells of origin, genomic and epigenetic abnormalities, molecular alterations, chemoresistance, and therapies.

Long Non-Coding RNA-PAICC Promotes the Tumorigenesis of Human Intrahepatic Cholangiocarcinoma by Increasing YAP1 Transcription

Intrahepatic cholangiocarcinoma (ICC) is a heterogeneous hepatobiliary tumor with poor prognosis, and it lacks reliable prognostic biomarkers and effective therapeutic targets. Long non-coding RNAs (lncRNAs) have been documented to be involved in the progression of various cancers. However, the role of lncRNAs in ICC remains largely unknown. In the present work, we used bioinformatics analysis to identify the differentially expressed lncRNAs in human ICC tissues, among which lncRNA-PAICC was found to be an independent prognostic marker in ICC. Moreover, lncRNA-PAICC promoted the proliferation and invasion of ICC cells. Mechanistically, lncRNA-PAICC acted as a competitive endogenous RNA (ceRNA) that directly sponged the tumor suppressive microRNAs miR-141-3p and miR-27a-3p. The competitive binding property was essential for lncRNA-PAICC to promote tumor growth and metastasis through activating the Hippo pathway. In summary, our results highlighted the important role of the lncRNA-PAICC-miR-141-3p/27a-3p-Yap1 axis in ICC, which offers a novel perspective on the molecular pathogenesis and may serve as a potential target for antimetastatic molecular therapies of ICC.

Cholangiocarcinoma 2020: the next horizon in mechanisms and management

Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant tumours that can arise at any point of the biliary tree. Their incidence is increasing globally, currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies. The silent presentation of these tumours combined with their highly aggressive nature and refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all cancer-related deaths worldwide yearly. The current diagnosis of CCA by non-invasive approaches is not accurate enough, and histological confirmation is necessary. Furthermore, the high heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises the efficacy of the available therapies. In the past decade, increasing efforts have been made to understand the complexity of these tumours and to develop new diagnostic tools and therapies that might help to improve patient outcomes. In this expert Consensus Statement, which is endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin, genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments. Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted.

Targeting CLK3 inhibits the progression of cholangiocarcinoma by reprogramming nucleotide metabolism

CDC-like kinase 3 (CLK3) is a dual specificity kinase that functions on substrates containing serine/threonine and tyrosine. But its role in human cancer remains unknown. Herein, we demonstrated that CLK3 was significantly up-regulated in cholangiocarcinoma (CCA) and identified a recurrent Q607R somatic substitution that represented a gain-of-function mutation in the CLK3 kinase domain. Gene ontology term enrichment suggested that high CLK3 expression in CCA patients mainly was associated with nucleotide metabolism reprogramming, which was further confirmed by comparing metabolic profiling of CCA cells. CLK3 directly phosphorylated USP13 at Y708, which promoted its binding to c-Myc, thereby preventing Fbxl14-mediated c-Myc ubiquitination and activating the transcription of purine metabolic genes. Notably, the CCA-associated CLK3-Q607R mutant induced USP13-Y708 phosphorylation and enhanced the activity of c-Myc. In turn, c-Myc transcriptionally up-regulated CLK3. Finally, we identified tacrine hydrochloride as a potential drug to inhibit aberrant CLK3-induced CCA. These findings demonstrate that CLK3 plays a crucial role in CCA purine metabolism, suggesting a potential therapeutic utility.

Core Hippo pathway components act as a brake on Yap and Taz in the development and maintenance of the biliary network

The development of the biliary system is a complex yet poorly understood process, with relevance to multiple diseases, including biliary atresia, choledochal cysts and gallbladder agenesis. We present here a crucial role for Hippo-Yap/Taz signaling in this context. Analysis of sav1 mutant zebrafish revealed dysplastic morphology and expansion of both intrahepatic and extrahepatic biliary cells, and ultimately larval lethality. Biliary dysgenesis, but not larval lethality, is driven primarily by Yap signaling. Re-expression of Sav1 protein in sav1-/- hepatocytes is able to overcome these initial deficits and allows sav1-/- fish to survive, suggesting cell non-autonomous signaling from hepatocytes. Examination of sav1-/- rescued adults reveals loss of gallbladder and formation of dysplastic cell masses expressing biliary markers, suggesting roles for Hippo signaling in extrahepatic biliary carcinomas. Deletion of stk3 revealed that the phenotypes observed in sav1 mutant fish function primarily through canonical Hippo signaling and supports a role for phosphatase PP2A, but also suggests Sav1 has functions in addition to facilitating Stk3 activity. Overall, this study defines a role for Hippo-Yap signaling in the maintenance of both intra- and extrahepatic biliary ducts.

Targeting cancer stem cells in cholangiocarcinoma (Review)

The incidence of cholangiocarcinoma has been increasing steadily over the past 50 years, but the survival rates remained low due to the disease being highly resistant to non-surgical treatment interventions. Cancer stem cell markers are expressed in cholangiocarcinoma, suggesting that they serve a significant role in the physiology of the disease. Cancer stem cells are frequently implicated in tumor relapse and acquired resistance to a number of therapeutic strategies, including chemotherapy, radiation and immune checkpoint inhibitors. Novel targeted therapies to eradicate cancer stem cells may assist in overcoming treatment resistance in cholangiocarcinoma and reduce the rates of relapse and recurrence. Several signaling pathways have been previously documented to regulate the development and survival of cancer stem cells, including Notch, janus kinase/STAT, Hippo/yes-associated protein 1 (YAP1), Wnt and Hedgehog signaling. Although pharmacological agents have been developed to target these pathways, only modest effects were reported in clinical trials. The Hippo/YAP1 signaling pathway has come to the forefront in the field of cancer stem cell research due to its reported involvement in epithelium-mesenchymal transition, cell adhesion, organogenesis and tumorigenesis. In the present article, recent findings in terms of cancer stem cell research in cholangiocarcinoma were reviewed, where the potential therapeutic targeting of cancer stem cells in this disease was discussed.

Genetic Mouse Models as In Vivo Tools for Cholangiocarcinoma Research

Cholangiocarcinoma (CCA) is a genetically and histologically complex disease with a highly dismal prognosis. A deeper understanding of the underlying cellular and molecular mechanisms of human CCA will increase our current knowledge of the disease and expedite the eventual development of novel therapeutic strategies for this fatal cancer. This endeavor is effectively supported by genetic mouse models, which serve as sophisticated tools to systematically investigate CCA pathobiology and treatment response. These in vivo models feature many of the genetic alterations found in humans, recapitulate multiple hallmarks of cholangiocarcinogenesis (encompassing cell transformation, preneoplastic lesions, established tumors and metastatic disease) and provide an ideal experimental setting to study the interplay between tumor cells and the surrounding stroma. This review is intended to serve as a compendium of CCA mouse models, including traditional transgenic models but also genetically flexible approaches based on either the direct introduction of DNA into liver cells or transplantation of pre-malignant cells, and is meant as a resource for CCA researchers to aid in the selection of the most appropriate in vivo model system.

Recreating Tumour Complexity in a Dish: Organoid Models to Study Liver Cancer Cells and their Extracellular Environment

Primary liver cancer, consisting predominantly of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), remains one of the most lethal malignancies worldwide. This high malignancy is related to the complex and dynamic interactions between tumour cells, stromal cells and the extracellular environment. Novel in vitro models that can recapitulate the tumour are essential in increasing our understanding of liver cancer. Herein, primary liver cancer-derived organoids have opened up new avenues due to their patient-specificity, self-organizing ability and potential recapitulation of many of the tumour properties. Organoids are solely of epithelial origin, but incorporation into co-culture models can enable the investigation of the cellular component of the tumour microenvironment. However, the extracellular component also plays a vital role in cancer progression and representation is lacking within current in vitro models. In this review, organoid technology is discussed in the context of liver cancer models through comparisons to other cell culture systems. In addition, the role of the tumour extracellular environment in primary liver cancer will be highlighted with an emphasis on its importance in in vitro modelling. Converging novel organoid-based models with models incorporating the native tumour microenvironment could lead to experimental models that can better recapitulate liver tumours in vivo.