YAP promotes proliferation, chemoresistance, and angiogenesis in human cholangiocarcinoma through TEAD transcription factors

Immunohistochemical Expression of PARK2 and YAP in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma

INTRODUCTION

Oral squamous cell carcinoma is the most prevalent of all the oral cancers. There is no definitive marker available for its early diagnosis and its effective prognosis. YAP serves as a transcriptional regulator in hippo tumor suppressor pathway thereby activating the transcription of genes taking part in cellular proliferation, alteration, migration, and invasion. On the contrary, PARK2 acts as a tumor suppressor and has been widely explored in various malignancies. However, its role in OSCC carcinogenesis is untrodden.

AIM

To evaluate the Immunohistochemical expression of YAP and PARK2 in oral epithelial dysplasia and Oral Squamous Cell Carcinoma and establish them as prognostic markers.

MATERIAL AND METHOD

The study sample consisted of 70 formalin fixed paraffin embedded tissue sections of normal oral mucosa (10), oral epithelial dysplasia (30) and oral squamous cell carcinoma (30). Immunohistochemical analysis of YAP and PARK2 was done and final scores were calculated. Further, the markers were graded as low and high expression groups. Statistical analysis was done using chi-square test, cox regression analysis and Spearman's correlation. Kaplan Meier plot for survival analysis was also plotted.

RESULT

Immunohistochemical expression of YAP depicted a gradual incline from normal oral mucosa to oral squamous cell carcinoma while PARK2 showed a reverse trend. Significant difference of YAP and PARK2 expression between three groups was noted. Inverse moderate degree of correlation was observed between both the markers in OSCC group.

CONCLUSION

Concomitant immunoexpression of YAP and PARK2 with a moderate degree of inverse correlation from normal oral mucosa to oral squamous cell carcinoma could probably serve as diagnostic and prognostic markers as they might act through a common mechanism, probably hippo/YAP signaling, which could be further confirmed by larger sample size, including longer follow up in future studies.

Molecular mechanisms of Hippo pathway in tumorigenesis: therapeutic implications

The Hippo signaling pathway is a pivotal regulator of tissue homeostasis, organ size, and cell proliferation. Its dysregulation is profoundly implicated in various forms of cancer, making it a highly promising target for therapeutic intervention. This review extensively evaluates the mechanisms underlying the dysregulation of the Hippo pathway in cancer cells and the molecular processes linking these alterations to tumorigenesis. Under normal physiological conditions, the Hippo pathway is a guardian, ensuring controlled cellular proliferation and programmed cell death. However, numerous mutations and epigenetic modifications can disrupt this equilibrium in cancer cells, leading to unchecked cell proliferation, enhanced survival, and metastatic capabilities. The pathway's interaction with other critical signaling networks, including Wnt/β-catenin, PI3K/Akt, TGF-β/SMAD, and EGFR pathways, further amplifies its oncogenic potential. Central to these disruptions is the activation of YAP and TAZ transcriptional coactivators, which drive the expression of genes that promote oncogenesis. This review delves into the molecular mechanisms responsible for the dysregulation of the Hippo pathway in cancer, elucidating how these disruptions contribute to tumorigenesis. We also explore potential therapeutic strategies, including inhibitors targeting YAP/TAZ activity and modulators of upstream signaling components. Despite significant advancements in understanding the Hippo pathway's role in cancer, numerous questions remain unresolved. Continued research is imperative to unravel the complex interactions within this pathway and to develop innovative and effective therapies for clinical application. In conclusion, the comprehensive understanding of the Hippo pathway's regulatory mechanisms offers significant potential for advancing cancer therapies, regenerative medicine, and treatments for chronic diseases. The translation of these insights into clinical practice will necessitate collaborative efforts from researchers, clinicians, and pharmaceutical developers to bring novel and effective therapies to patients, ultimately improving clinical outcomes and advancing the field of oncology.

Transposon-based oncogene integration in Abcb4(Mdr2)-/- mice recapitulates high susceptibility to cholangiocarcinoma in primary sclerosing cholangitis

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a dreaded complication of primary sclerosing cholangitis (PSC) that is difficult to diagnose and associated with high mortality. A lack of animal models of CCA recapitulating the hepatic microenvironment of sclerosing cholangitis has hindered the development of novel treatments. Herein, we sought to develop a mouse model of PSC-associated CCA.

METHODS

Ten-week-old Mdr2-/- mice with congenital PSC-like disease, and healthy wild-type littermates were subjected to either modified retrograde biliary instillation or hydrodynamic tail vein injection of a sleeping beauty transposon-transposase plasmid system with activated AKT (myr-AKT) and Yap (YapS127A) proto-oncogenes (SB AKT/YAP1). The role of TGFβ was interrogated via ALK5 inhibitor (SB-525334) administration. Tumor phenotype, burden and desmoplastic reaction were analyzed histologically and via RNA sequencing.

RESULTS

While SB AKT/YAP1 plasmids administered via retrograde biliary injection caused tumors in Mdr2-/-, only 26.67% (4/15) of these tumors were CCA. Alternatively, hydrodynamic tail vein injection of SB AKT/YAP1 resulted in robust tumorigenesis in all fibrotic Mdr2-/- mice with high CCA burden compared to healthy mice. Tumors phenotypically resembled human CCA, expressed multiple CCA (but not hepatocellular carcinoma) markers, and exhibited a profound desmoplastic reaction. RNA sequencing analysis revealed profound transcriptional changes in CCA evolving in a PSC-like context, with specific alterations in multiple immune pathways. Pharmacological TGFβ inhibition led to enhanced immune cell tumor infiltration, reduced tumor burden and suppressed desmoplastic collagen accumulation compared to placebo.

CONCLUSION

We established a new high-fidelity cholangiocarcinoma model in mice, termed SB CCA.Mdr2-/-, which recapitulates the increased susceptibility to CCA in the setting of biliary injury and fibrosis observed in PSC. Through transcriptomics and pharmacological studies, we show dysregulation of multiple immune pathways and TGFβ signaling as potential drivers of CCA in a PSC-like microenvironment.

IMPACT AND IMPLICATIONS

Animal models for primary sclerosing cholangitis (PSC)-related cholangiocarcinoma (PSC-CCA) are lacking. Thus, we have developed and characterized a new mouse model of PSC-CCA, termed SB CCA.Mdr2-/-, which features reliable tumor induction on a PSC-like background of biliary injury and fibrosis. Global gene expression alterations were identified and standardized tools, including automated whole slide image analysis methodology for tumor burden and feature analysis, were established to enable systematic research into PSC-CCA biology and formal preclinical drug testing.

Research Advances in Adenomyosis-Related Signaling Pathways and Promising Targets

Adenomyosis is a benign gynecological condition characterized by the proliferation of the endometrial stroma and glands into the myometrium, uterine volume enlargement, and peripheral smooth muscle hypertrophy. The typical clinical symptoms include chronic pelvic pain, abnormal uterine bleeding, and subfertility, all of which significantly impact quality of life. There are no effective prevention or treatment strategies for adenomyosis, partly due to a limited understanding of the pathological mechanisms underlying the initiation and progression of the disease. Given that signaling pathways play a crucial role in the development of adenomyosis, a better understanding of these signaling pathways is essential for identifying therapeutic targets and advancing drug development. The occurrence and progression of adenomyosis are closely linked to various underlying pathophysiological mechanisms, including proliferation, migration, invasion, fibrosis, angiogenesis, inflammation, oxidative stress, immune response, and epigenetic changes. This review summarizes the signaling pathways and targets associated with the pathogenesis of adenomyosis, including CXCL/CXCR, NLRP3, NF-κB, TGF-β/smad, VEGF, Hippo/YAP, PI3K/Akt/mTOR, JAK/STAT, and other relevant pathways. In addition, it identifies promising future targets for the development of adenomyosis treatment, such as m6A, GSK3β, sphks, etc.

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.

Notch-Driven Cholangiocarcinogenesis Involves the Hippo Pathway Effector TAZ via METTL3-m6A-YTHDF1

BACKGROUND & AIMS

Notch and TAZ are implicated in cholangiocarcinogenesis, but whether and how these oncogenic molecules interact remain unknown.

METHODS

The development of cholangiocarcinoma (CCA) was induced by hydrodynamic tail vein injection of oncogenes (Notch1 intracellular domain [NICD]/AKT) to the FVB/NJ mice. CCA xenograft was developed by inoculation of human CCA cells into the livers of SCID mice. Tissues and cells were analyzed using quantitative reverse transcription polymerase chain reaction, Western blotting analyses, immunohistochemistry, chromatin immunoprecipitation-quantitative polymerase chain reaction and WST-1 cell proliferation assay.

RESULTS

Our experimental findings show that TAZ is indispensable in NICD-driven cholangiocarcinogenesis. Notch activation induces the expression of methyltransferase like-3 (METTL3), which catalyzes N6-methyladenosine modification of TAZ mRNA and that this mechanism plays a central role in the crosstalk between Notch and TAZ in CCA cells. Mechanistically, Notch regulates the expression of METTL3 through the binding of NICD to its downstream transcription factor CSL in the promoter region of METTL3. METTL3 in turn mediates N6-methyladenosine modification of TAZ mRNA, which is recognized by the m6A reader YTHDF1 to enhance TAZ protein translation. We observed that inhibition of Notch signaling decreased the protein levels of both MELLT3 and TAZ. Depletion of METTL3 by short hairpin RNAs or by the next generation GapmeR antisense oligonucleotides decreased the level of TAZ protein and inhibited the growth of human CCA cells in vitro and in mice.

CONCLUSIONS

This study describes a novel Notch-METTL3-TAZ signaling cascade, which is important in CCA development and progression. Our experimental results provide new insight into how the Notch pathway cooperates with TAZ signaling in CCA, and the findings may have important therapeutic implications.

Magnetically Integrated Tumor-Vascular Interface System to Mimic Pro-angiogenic Endothelial Dysregulations for On-Chip Drug Testing

The tumor-vascular interface is a critical component of the tumor microenvironment that regulates all of the dynamic interactions between a growing tumor and the endothelial lining of the surrounding vasculature. In this paper, we report the design and development of a custom-engineered tumor-vascular interface system for investigating the early stage tumor-mediated pro-angiogenic dysfunctional behavior of the endothelium. Using representative endothelial cells and triple negative breast cancer cell lines, we established a biomimetic interface between a three-dimensional tumor tissue across a mature, functional endothelial barrier using a magnetically hybrid-integrated tumor-vascular interface system, wherein vasculature-like features containing a monolayer of endothelial cell culture on porous microfluidic channel surfaces were magnetically attached to tumor spheroids generated on a composite polymer-hydrogel microwell plate and embedded in a collagen matrix. Tumor-mediated endothelial microdynamics were characterized by their hallmark behavior such as loss of endothelial adherens junctions, increased cell density, proliferation, and changes in cell spreading and corroborated with endothelial YAP/TAZ nuclear translocation. We further confirm the feasibility of drug-mediated reversal of this pro-angiogenic endothelial organization through two different signaling mechanisms, namely, inhibition of the vascular endothelial growth factor pathway and the Notch signaling pathway, thereby demonstrating the utility of the tumor-vascular interface platform for rapid, early stage prediction of antiangiogenic drug efficacy. Overall, our work emphasizes the importance of our strategic engineering approach for identifying some unique, physiologically relevant aspects of the tumor-vascular interface, which are otherwise difficult to implement using standard in vitro approaches.

HAX1-Overexpression Augments Cardioprotective Efficacy of Stem Cell-Based Therapy Through Mediating Hippo-Yap Signaling

Although stem/progenitor cell therapy shows potential for myocardial infarction repair, enhancing the therapeutic efficacy could be achieved through additional genetic modifications. HCLS1-associated protein X-1 (HAX1) has been identified as a versatile modulator responsible for cardio-protective signaling, while its role in regulating stem cell survival and functionality remains unknown. In this study, we investigated whether HAX1 can augment the protective potential of Sca1+ cardiac stromal cells (CSCs) for myocardial injury. The overexpression of HAX1 significantly increased cell proliferation and conferred enhanced resistance to hypoxia-induced cell death in CSCs. Mechanistically, HAX1 can interact with Mst1 (a prominent conductor of Hippo signal transduction) and inhibit its kinase activity for protein phosphorylation. This inhibition led to enhanced nuclear translocation of Yes-associated protein (YAP) and activation of downstream therapeutic-related genes. Notably, HAX1 overexpression significantly increased the pro-angiogenic potential of CSCs, as demonstrated by elevated expression of vascular endothelial growth factors. Importantly, implantation of HAX1-overexpressing CSCs promoted neovascularization, protected against functional deterioration, and ameliorated cardiac fibrosis in ischemic mouse hearts. In conclusion, HAX1 emerges as a valuable and efficient inducer for enhancing the effectiveness of cardiac stem or progenitor cell therapeutics.

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.

Activation of Hepatocyte Growth Factor/MET Signaling as a Mechanism of Acquired Resistance to a Novel YAP1/TEAD Small Molecule Inhibitor

Many tumor types harbor alterations in the Hippo pathway, including mesothelioma, where a high percentage of cases are considered YAP1/TEAD dependent. Identification of autopalmitoylation sites in the hydrophobic palmitate pocket of TEADs, which may be necessary for YAP1 protein interactions, has enabled modern drug discovery platforms to generate compounds that allosterically inhibit YAP1/TEAD complex formation and transcriptional activity. We report the discovery and characterization of a novel YAP1/TEAD inhibitor MRK-A from an aryl ether chemical series demonstrating potent and specific inhibition of YAP1/TEAD activity. In vivo, MRK-A showed a favorable tolerability profile in mice and demonstrated pharmacokinetics suitable for twice daily oral dosing in preclinical efficacy studies. Importantly, monotherapeutic targeting of YAP1/TEAD in preclinical models generated regressions in a mesothelioma CDX model; however, rapid resistance to therapy was observed. RNA-sequencing of resistant tumors revealed mRNA expression changes correlated with the resistance state and a marked increase of hepatocyte growth factor (HGF) expression. In vitro, exogenous HGF was able to fully rescue cytostasis induced by MRK-A in mesothelioma cell lines. In addition, co-administration of small molecule inhibitors of the MET receptor tyrosine kinase suppressed the resistance generating effect of HGF on MRK-A induced growth inhibition. In this work, we report the structure and characterization of MRK-A, demonstrating potent and specific inhibition of YAP1/TAZ-TEAD-mediated transcriptional responses, with potential implications for treating malignancies driven by altered Hippo signaling, including factors resulting in acquired drug resistance.

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.

YAP1-induced RBM24 promotes the tumorigenesis of triple-negative breast cancer through the β-catenin pathway

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and refractory to current treatments. RBM24 is an RNA-binding protein and shows the ability to regulate tumor progression in multiple cancer types. However, its role in TNBC is still unclear. In this study, we analyzed publicly available profiling data from TNBC tissues and cells. Loss- and gain-of-function experiments were performed to determine the function of RBM24 in TNBC cells. The mechanism for RBM24 action in TNBC was investigated. RBM24 was deregulated in TNBC tissues and TNBC cells with depletion of SIPA1, YAP1, or ARID1A, three key regulators of TNBC. Compared to MCF10A breast epithelial cells, TNBC cells had higher levels of RBM24. Knockdown of RBM24 inhibited TNBC cell proliferation, colony formation, and tumorigenesis, while overexpression of RBM24 promoted aggressive phenotype in TNBC cells. YAP1 overexpression induced the expression of RBM24 and the RBM24 promoter-driven luciferase reporter. YAP1 was enriched at the promoter region of RBM24. Overexpression of RBM24 increased β-catenin-dependent transcriptional activity. Most importantly, knockdown of CTNNB1 rescued RBM24 aggressive phenotype in TNBC cells. Collectively, the YAP1/RBM24/β-catenin axis plays a critical role in driving TNBC progression. RBM24 may represent a novel therapeutic target for TNBC treatment.

Signaling pathways in liver cancer: pathogenesis and targeted therapy

Liver cancer remains one of the most prevalent malignancies worldwide with high incidence and mortality rates. Due to its subtle onset, liver cancer is commonly diagnosed at a late stage when surgical interventions are no longer feasible. This situation highlights the critical role of systemic treatments, including targeted therapies, in bettering patient outcomes. Despite numerous studies on the mechanisms underlying liver cancer, tyrosine kinase inhibitors (TKIs) are the only widely used clinical inhibitors, represented by sorafenib, whose clinical application is greatly limited by the phenomenon of drug resistance. Here we show an in-depth discussion of the signaling pathways frequently implicated in liver cancer pathogenesis and the inhibitors targeting these pathways under investigation or already in use in the management of advanced liver cancer. We elucidate the oncogenic roles of these pathways in liver cancer especially hepatocellular carcinoma (HCC), as well as the current state of research on inhibitors respectively. Given that TKIs represent the sole class of targeted therapeutics for liver cancer employed in clinical practice, we have particularly focused on TKIs and the mechanisms of the commonly encountered phenomena of its resistance during HCC treatment. This necessitates the imperative development of innovative targeted strategies and the urgency of overcoming the existing limitations. This review endeavors to shed light on the utilization of targeted therapy in advanced liver cancer, with a vision to improve the unsatisfactory prognostic outlook for those patients.

Loci cg06256735 and cg15815843 in the MFAP5 gene regulatory regions are hypomethylated in varicose veins apparently due to active demethylation

Varicose vein disease (VVD) is a common health problem worldwide. Microfibril-associated protein 5 (MFAP5) is one of the potential key players in its pathogenesis. Our previous microarray analysis revealed the cg06256735 and cg15815843 loci in the regulatory regions of the MFAP5 gene as hypomethylated in varicose veins which correlated with its up-regulation. The aim of this work was to validate preliminary microarray data, estimate the level of 5-hydroxymethylcytosine (5hmC) at these loci, and determine the methylation status of one of them in different layers of the venous wall. For this, methyl- and hydroxymethyl-sensitive restriction techniques were used followed by real-time PCR and droplet digital PCR, correspondingly, as well as bisulfite pyrosequencing of +/- oxidized DNA. Our microarray data on hypomethylation at the cg06256735 and cg15815843 loci in whole varicose vein segments were confirmed and it was also demonstrated that the level of 5hmC at these loci is increased in VVD. Specifically, among other layers of the venous wall, tunica (t.) intima is the main contributor to hypomethylation at the cg06256735 locus in varicose veins. Thus, it was shown that hypomethylation at the cg06256735 and cg15815843 loci takes place in VVD, with evidence to suggest that it happens through their active demethylation leading to up-regulation of the MFAP5 gene, and t. intima is most involved in this biochemical process.

The interplay between hippo signaling and mitochondrial metabolism: Implications for cellular homeostasis and disease

Mitochondria are the membrane-bound organelles producing energy for cellular metabolic processes. They orchestrate diverse cell signaling cascades regulating cellular homeostasis. This functional versatility may be attributed to their ability to regulate mitochondrial dynamics, biogenesis, and apoptosis. The Hippo pathway, a conserved signaling pathway, regulates various cellular processes, including mitochondrial functions. Through its effectors YAP and TAZ, the Hippo pathway regulates transcription factors and creates a seriatim process that mediates cellular metabolism, mitochondrial dynamics, and survival. Mitochondrial dynamics also potentially regulates Hippo signaling activation, indicating a bidirectional relationship between the two. This review outlines the interplay between the Hippo signaling components and the multifaceted role of mitochondria in cellular homeostasis under physiological and pathological conditions.

Deciphering peri-implantitis: Unraveling signature genes and immune cell associations through bioinformatics and machine learning

Early diagnosis of peri-implantitis (PI) is crucial to understand its pathological progression and prevention. This study is committed to investigating the signature genes, relevant signaling pathways and their associations with immune cells in PI. We analyzed differentially expressed genes (DEGs) from a PI dataset in the gene expression omnibus database. Functional enrichment analysis was conducted for these DEGs. Weighted Gene Co-expression Network Analysis was used to identify specific modules. Least absolute shrinkage and selection operator and support vector machine recursive feature elimination were ultimately applied to identify the signature genes. These genes were subsequently validated in an external dataset. And the immune cells infiltration was classified using CIBERSORT. A total of 180 DEGs were screened from GSE33774. Weighted Gene Co-expression Network Analysis revealed a significant association between the MEturquoise module and PI (cor = 0.6, P < .0001). Least absolute shrinkage and selection operator and support vector machine recursive feature elimination algorithms were applied to select the signature genes, containing myeloid-epithelial-reproductive tyrosine kinase, microfibrillar-associated protein 5, membrane-spanning 4A 4A, tribbles homolog 1. In the validation on the external dataset GSE106090, all these genes achieved area under curve values exceeding 0.95. GSEA analysis showed that these genes were correlated with the NOD-like receptor signaling pathway, metabolism of xenobiotics by cytochrome P450, and arachidonic acid metabolism. CIBERSORT revealed elevated levels of macrophage M2 and activated mast cells in PI. This study provides novel insights into understanding the molecular mechanisms of PI and contributes to advancements in its early diagnosis and prevention.

Knockdown of CCM3 promotes angiogenesis through activation and nuclear translocation of YAP/TAZ

Angiogenesis, a finely regulated process, plays a crucial role in the progression of various diseases. Cerebral cavernous malformation 3 (CCM3), alternatively referred to as programmed cell death 10 (PDCD10), stands as a pivotal functional gene with a broad distribution across the human body. However, the precise role of CCM3 in angiogenesis regulation has remained elusive. YAP/TAZ, as core components of the evolutionarily conserved Hippo pathway, have garnered increasing attention as a novel mechanism in angiogenesis regulation. Nonetheless, whether CCM3 regulates angiogenesis through YAP/TAZ mediation has not been comprehensively explored. In this study, our primary focus centers on investigating the regulation of angiogenesis through CCM3 knockdown mediated by YAP/TAZ. Silencing CCM3 significantly enhances the proliferation, migration, and tubular formation of human umbilical vein endothelial cells (HUVECs), thereby promoting angiogenesis. Furthermore, we observe an upregulation in the expression levels of VEGF and VEGFR2 within HUVECs upon silencing CCM3. Mechanistically, the evidence we provide suggests for the first time that endothelial cell CCM3 knockdown induces the activation and nuclear translocation of YAP/TAZ. Finally, we further demonstrate that the YAP/TAZ inhibitor verteporfin can reverse the pro-angiogenic effects of siCCM3, thereby confirming the role of CCM3 in angiogenesis regulation dependent on YAP/TAZ. In summary, our findings pave the way for potential therapeutic targeting of the CCM3-YAP/TAZ signaling axis as a novel approach to promote angiogenesis.

Therapeutic significance of tumor microenvironment in cholangiocarcinoma: focus on tumor-infiltrating T lymphocytes

Cholangiocarcinoma (CCA) is a highly aggressive type of adenocarcinoma distinguished by its invasiveness. Depending on specific anatomical positioning within the biliary tree, CCA can be categorized into intrahepatic CCA (ICCA), perihilar CCA (pCCA) and distal CCA (dCCA). In recent years, there has been a significant increase in the global prevalence of CCA. Unfortunately, many CCA patients are diagnosed at an advanced stage, which makes surgical resection impossible. Although systemic chemotherapy is frequently used as the primary treatment for advanced or recurrent CCA, its effectiveness is relatively low. Therefore, immunotherapy has emerged as a promising avenue for advancing cancer treatment research. CCA exhibits a complex immune environment within the stromal tumor microenvironment (TME), comprising a multifaceted immune landscape and a tumor-reactive stroma. A deeper understanding of this complex TME is indispensable for identifying potential therapeutic targets. Thus, targeting tumor immune microenvironment holds promise as an effective therapeutic strategy.

JUNB mediates oxaliplatin resistance via the MAPK signaling pathway in gastric cancer by chromatin accessibility and transcriptomic analysis

Currently, platinum-containing regimens are the most commonly used regimens for advanced gastric cancer patients, and chemotherapy resistance is one of the main reasons for treatment failure. Thus, it is important to reveal the mechanism of oxaliplatin resistance and to seek effective intervention strategies to improve chemotherapy sensitivity, thereby improving the survival and prognosis of gastric cancer patients. To understand the molecular mechanisms of oxaliplatin resistance, we generate an oxaliplatin-resistant gastric cancer cell line and conduct assay for transposase-accessible chromatin sequencing (ATAC-seq) and RNA sequencing (RNA-seq) for both parental and oxaliplatin-resistant AGS cells. A total of 3232 genomic regions are identified to have higher accessibility in oxaliplatin-resistant cells, and DNA-binding motif analysis identifies JUNB as the core transcription factor in the regulatory network. JUNB is overexpressed in oxaliplatin-resistant gastric cancer cells, and its upregulation is associated with poor prognosis in gastric cancer patients, which is validated by our tissue microarray data. Moreover, chromatin immunoprecipitation sequencing (ChIP-seq) analysis reveals that JUNB binds to the transcriptional start site of key genes involved in the MAPK signaling pathway. Knockdown of JUNB inhibits the MAPK signaling pathway and restores sensitivity to oxaliplatin. Combined treatment with the ERK inhibitor piperlongumine or MEK inhibitor trametinib effectively overcomes oxaliplatin resistance. This study provides evidence that JUNB mediates oxaliplatin resistance in gastric cancer by activating the MAPK pathway. The combination of MAPK inhibitors with oxaliplatin overcomes resistance to oxaliplatin, providing a promising treatment opportunity for oxaliplatin-resistant gastric cancer patients.

Panic at the Bile Duct: How Intrahepatic Cholangiocytes Respond to Stress and Injury

In the liver, biliary epithelial cells (BECs) line intrahepatic bile ducts (IHBDs) and are primarily responsible for modifying and transporting hepatocyte-produced bile to the digestive tract. BECs comprise only 3% to 5% of the liver by cell number but are critical for maintaining choleresis through homeostasis and disease. To this end, BECs drive an extensive morphologic remodeling of the IHBD network termed ductular reaction (DR) in response to direct injury or injury to the hepatic parenchyma. BECs are also the target of a broad and heterogenous class of diseases termed cholangiopathies, which can present with phenotypes ranging from defective IHBD development in pediatric patients to progressive periductal fibrosis and cancer. DR is observed in many cholangiopathies, highlighting overlapping similarities between cell- and tissue-level responses by BECs across a spectrum of injury and disease. The following core set of cell biological BEC responses to stress and injury may moderate, initiate, or exacerbate liver pathophysiology in a context-dependent manner: cell death, proliferation, transdifferentiation, senescence, and acquisition of neuroendocrine phenotype. By reviewing how IHBDs respond to stress, this review seeks to highlight fundamental processes with potentially adaptive or maladaptive consequences. A deeper understanding of how these common responses contribute to DR and cholangiopathies may identify novel therapeutic targets in liver disease.

The Inactivation of Hippo Signaling Pathway Promotes the Development of Adenomyosis by Regulating EMT, Proliferation, and Apoptosis of Cells

Adenomyosis is a benign gynecological disease. The pathogenesis of adenomyosis is still unclear. The Hippo signaling pathway is highly conserved in vivo and associated with endometriosis and various cancers. Our objective was to study the expression of Hippo signaling pathway-related proteins in the uterus of mice with and without adenomyosis. We also sought to determine the relationship between the Hippo signaling pathway and cell migration, invasion, proliferation, and apoptosis in adenomyosis. The inactivation of Hippo signaling pathway and abnormal expression of EMT-related proteins were observed in mice with adenomyosis. In vitro, the YAP inhibitor verteporfin can inhibit the proliferation and migration of Ishikawa cells and promote apoptosis, while inhibiting the EMT process. In addition, intraperitoneal injection of verteporfin inhibits EMT process and proliferation and promotes apoptosis of cells in the uterus of adenomyosis mice. It suggests that the Hippo signaling pathway participates in the EMT, proliferation, and apoptosis of cells in adenomyosis. In conclusion, these results suggest that Hippo signaling pathway may be involved in the development of adenomyosis by regulating EMT, proliferation, and apoptosis of cells, which provide a potential target for the treatment of adenomyosis.

Targeting MFAP5 in cancer-associated fibroblasts sensitizes pancreatic cancer to PD-L1-based immunochemotherapy via remodeling the matrix

Highly desmoplastic and immunosuppressive tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC) contributes to tumor progression and resistance to current therapies. Clues targeting the notorious stromal environment have offered hope for improving therapeutic response whereas the underlying mechanism remains unclear. Here, we find that prognostic microfibril associated protein 5 (MFAP5) is involved in activation of cancer-associated fibroblasts (CAFs). Inhibition of MFAP5^highCAFs shows synergistic effect with gemcitabine-based chemotherapy and PD-L1-based immunotherapy. Mechanistically, MFAP5 deficiency in CAFs downregulates HAS2 and CXCL10 via MFAP5/RCN2/ERK/STAT1 axis, leading to angiogenesis, hyaluronic acid (HA) and collagens deposition reduction, cytotoxic T cells infiltration, and tumor cells apoptosis. Additionally, in vivo blockade of CXCL10 with AMG487 could partially reverse the pro-tumor effect from MFAP5 overexpression in CAFs and synergize with anti-PD-L1 antibody to enhance the immunotherapeutic effect. Therefore, targeting MFAP5^highCAFs might be a potential adjuvant therapy to enhance the immunochemotherapy effect in PDAC via remodeling the desmoplastic and immunosuppressive microenvironment.

The deubiquitinating enzyme UCHL3 promotes anaplastic thyroid cancer progression and metastasis through Hippo signaling pathway

Yes-associated protein (YAP) is one of major key effectors of the Hippo pathway and the mechanism supporting abnormal YAP expression in Anaplastic thyroid carcinoma (ATC) remains to be characterized. Here, we identified ubiquitin carboxyl terminal hydrolase L3 (UCHL3) as a bona fide deubiquitylase of YAP in ATC. UCHL3 stabilized YAP in a deubiquitylation activity-dependent manner. UCHL3 depletion significantly decreased ATC progression, stem-like and metastasis, and increased cell sensitivity to chemotherapy. Depletion of UCHL3 decreased the YAP protein level and the expression of YAP/TEAD target genes in ATC. UCHL3 promoter analysis revealed that TEAD4, through which YAP bind to DNA, activated UCHL3 transcription by binding to the promoter of UCHL3. In general, our results demonstrated that UCHL3 plays a pivotal role in stabilizing YAP, which in turn facilitates tumorigenesis in ATC, suggesting that UCHL3 may prove to be a potential target for the treatment of ATC.

Microbiota-derived tryptophan metabolites indole-3-lactic acid is associated with intestinal ischemia/reperfusion injury via positive regulation of YAP and Nrf2

BACKGROUND

Lactobacillus has been demonstrated to serve a protective role in intestinal injury. However, the relationship between Lactobacillus murinus (L. murinus)-derived tryptophan metabolites and intestinal ischemia/reperfusion (I/R) injury yet to be investigated. This study aimed to evaluate the role of L. murinus-derived tryptophan metabolites in intestinal I/R injury and the underlying molecular mechanism.

METHODS

Liquid chromatograph mass spectrometry analysis was used to measure the fecal content of tryptophan metabolites in mice undergoing intestinal I/R injury and in patients undergoing cardiopulmonary bypass (CPB) surgery. Immunofluorescence, quantitative RT-PCR, Western blot, and ELISA were performed to explore the inflammation protective mechanism of tryptophan metabolites in WT and Nrf2-deficient mice undergoing intestinal I/R, hypoxia-reoxygenation (H/R) induced intestinal organoids.

RESULTS

By comparing the fecal contents of three L. murinus-derived tryptophan metabolites in mice undergoing intestinal I/R injury and in patients undergoing cardiopulmonary bypass (CPB) surgery. We found that the high abundance of indole-3-lactic acid (ILA) in the preoperative feces was associated with better postoperative intestinal function, as evidenced by the correlation of fecal metabolites with postoperative gastrointestinal function, serum I-FABP and D-Lactate levels. Furthermore, ILA administration improved epithelial cell damage, accelerated the proliferation of intestinal stem cells, and alleviated the oxidative stress of epithelial cells. Mechanistically, ILA improved the expression of Yes Associated Protein (YAP) and Nuclear Factor erythroid 2-Related Factor 2 (Nrf2) after intestinal I/R. The YAP inhibitor verteporfin (VP) reversed the anti-inflammatory effect of ILA, both in vivo and in vitro. Additionally, we found that ILA failed to protect epithelial cells from oxidative stress in Nrf2 knockout mice under I/R injury.

CONCLUSIONS

The content of tryptophan metabolite ILA in the preoperative feces of patients is negatively correlated with intestinal function damage under CPB surgery. Administration of ILA alleviates intestinal I/R injury via the regulation of YAP and Nrf2. This study revealed a novel therapeutic metabolite and promising candidate targets for intestinal I/R injury treatment.

Helicobacter pylori-induced aberrant demethylation and expression of GNB4 promotes gastric carcinogenesis via the Hippo-YAP1 pathway

BACKGROUND

Helicobacter pylori (H. pylori) infection causes aberrant DNA methylation and contributes to the risk of gastric cancer (GC). Guanine nucleotide-binding protein subunit beta-4 (GNB4) is involved in various tumorigenic processes. We found an aberrant methylation level of GNB4 in H. pylori-induced GC in our previous bioinformatic analysis; however, its expression and underlying molecular mechanisms are poorly understood.

METHODS

The expression, underlying signaling pathways, and clinical significance of GNB4 were analyzed in a local cohort of 107 patients with GC and several public databases. H. pylori infection was induced in in vitro and in vivo models. Methylation-specific PCR, pyrosequencing, and mass spectrometry analysis were used to detect changes in methylation levels. GNB4, TET1, and YAP1 were overexpressed or knocked down in GC cell lines. We performed gain- and loss-of-function experiments, including CCK-8, EdU, colony formation, transwell migration, and invasion assays. Nude mice were injected with genetically manipulated GC cells, and the growth of xenograft tumors and metastases was measured. Real-time quantitative PCR, western blotting, immunofluorescence, immunohistochemistry, chromatin immunoprecipitation, and co-immunoprecipitation experiments were performed to elucidate the underlying molecular mechanisms.

RESULTS

GNB4 expression was significantly upregulated in GC and correlated with aggressive clinical characteristics and poor prognosis. Increased levels of GNB4 were associated with shorter survival times. Infection with H. pylori strains 26695 and SS1 induced GNB4 mRNA and protein expression in GC cell lines and mice. Additionally, silencing of GNB4 blocked the pro-proliferative, metastatic, and invasive ability of H. pylori in GC cells. H. pylori infection remarkably decreased the methylation level of the GNB4 promoter region, particularly at the CpG#5 site (chr3:179451746-179451745). H. pylori infection upregulated TET1 expression via activation of the NF-κB. TET binds to the GNB4 promoter region which undergoes demethylation modification. Functionally, we identified that GNB4 induced oncogenic behaviors of tumors via the Hippo-YAP1 pathway in both in vitro and in vivo models.

CONCLUSIONS

Our findings demonstrate that H. pylori infection activates the NF-κB-TET1-GNB4 demethylation-YAP1 axis, which may be a potential therapeutic target for GC.

Angiotensin receptor blockers retard the progression and fibrosis via inhibiting the viability of AGTR1+ CAFs in intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal malignancy characterized by massive fibrosis and has ineffective adjuvant therapies. Here, we demonstrate the potential of angiotensin receptor blockers (ARBs) in targeting iCCA.

METHODS

Masson's trichrome staining was used to assess the effect of ARBs in iCCA specimens, CCK8 and gel contraction assays in vitro and in xenograft models in vivo. RNA-seq and ATAC-seq were used for mechanistic investigations.

RESULTS

Patients with iCCA who were administered ARBs had a better prognosis and a lower proportion of tumour stroma, indicating alleviated fibrosis. The presence of AGTR1, the ARBs receptor, is associated with a poor prognosis of iCCA and is highly expressed in tumour tissues and cancer-associated fibroblasts (CAFs). The ARBs strongly attenuated the viability of AGTR1+ CAFs in vitro and retarded tumour progression and fibrosis in xenograft models of co-cultured CAFs and iCCA cells. Still, they did not have a significant effect on AGTR1- CAFs. Moreover, ARBs decreased the secretion of AGTR1+ CAF-derived MFAP5 via the Hippo pathway, weakened the interaction between CAFs and iCCA cells, and impaired the aggressiveness of iCCA cells by attenuating the activation of the Notch1 pathway in iCCA cells.

CONCLUSIONS

ARBs exhibit anti-fibrotic function by inhibiting the viability of AGTR1+ CAFs. These findings support using ARBs as a novel therapeutic option for targeting iCCA.

Specific Overexpression of YAP in Vascular Smooth Muscle Attenuated Abdominal Aortic Aneurysm Formation by Activating Elastic Fiber Assembly via LTBP4

Abdominal aortic aneurysm (AAA) is a fatal vascular disease. Vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of AAA. Increasing evidence has shown that Yes-associated protein (YAP) is involved in diverse vascular diseases. However, the role of YAP in AAA remains unclear. The current study aimed to determine the role of YAP in AAA formation and the underlying mechanism. We found that YAP expression in VSMCs was markedly decreased in human and experimental AAA samples. Furthermore, VSMC-specific YAP overexpression prevented several pathogenic factor-induced AAA. Mechanistically, YAP overexpression in VSMCs promoted latent transforming growth factor-β binding protein 4 (LTBP4) expression, an important factor in elastic fiber assembly. Finally, silencing of LTBP4 in VSMCs abolished the protective role of YAP in AAA formation in vivo. Our results suggest that YAP promotes LTBP4-mediated elastic fibril assembly in VSMCs, which mitigates elastin degradation and AAA formation.

PXR triggers YAP-TEAD binding and Sirt2-driven YAP deacetylation and polyubiquitination to promote liver enlargement and regeneration in mice

Pregnane X receptor (PXR) plays an important role in the regulation of metabolic homeostasis. Yes-associated protein (YAP) is a critical regulator of liver size and liver regeneration. Recently, we reported that PXR-induced liver enlargement and regeneration depend on YAP signalling, but the underlying mechanisms remain unclear. This study aimed to reveal how PXR regulates or interacts with YAP signalling during PXR-induced hepatomegaly and liver regeneration. Immunoprecipitation (IP), Co-IP and GST pull-down assays were performed in vitro to reveal the regulatory mechanisms involved in the PXR-YAP interaction. The roles of YAP-TEAD binding and Sirt2-driven deacetylation and polyubiquitination of YAP were further investigated in vitro and in vivo. The results showed that the ligand-binding domain (LBD) of PXR and the WW domain of YAP were critical for the PXR-YAP interaction. Furthermore, disruption of the YAP-TEAD interaction using the binding inhibitor verteporfin significantly decreased PXR-induced liver enlargement and regeneration after 70 % partial hepatectomy (PHx). Mechanistically, PXR activation significantly decreased YAP acetylation, which was interrupted by the sirtuin inhibitor nicotinamide (NAM). In addition, p300-induced YAP acetylation contributed to K48-linked YAP ubiquitination. Interestingly, PXR activation remarkably inhibited K48-linked YAP ubiquitination while inducing K63-linked YAP polyubiquitination. Sirt2 interference abolished the deacetylation and K63-linked polyubiquitination of YAP, suggesting that the PXR-induced deacetylation and polyubiquitination of YAP are Sirt2 dependent. Taken together, this study demonstrates that PXR induce liver enlargement and regeneration via the regulation of YAP acetylation and ubiquitination and YAP-TEAD binding, providing evidences for using PXR as potential target to promote hepatic development and liver repair.

YAP/TAZ as master regulators in cancer: modulation, function and therapeutic approaches

Our understanding of the function of the transcriptional regulators YAP and TAZ (YAP/TAZ) in cancer is advancing. In this Review, we provide an update on recent progress in YAP/TAZ biology, their regulation by Hippo signaling and mechanotransduction and highlight open questions. YAP/TAZ signaling is an addiction shared by multiple tumor types and their microenvironments, providing many malignant attributes. As such, it represents an important vulnerability that may offer a broad window of therapeutic efficacy, and here we give an overview of the current treatment strategies and pioneering clinical trials.

LGR5 promotes invasion and migration by regulating YAP activity in hypopharyngeal squamous cell carcinoma cells under inflammatory condition

High leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) expression caused by an inflammatory condition was reported to promote tumor proliferation and the epithelial-mesenchymal transition (EMT) in various malignant tumors, but those effects have not been studied in hypopharyngeal squamous cell carcinoma (HSCC) and the molecular mechanism remains unclear. This study was aimed to determine whether YAP/TAZ is involved in the regulation of LGR5 expression in the inflammatory condition. Human hypopharyngeal carcinoma FaDu cells were stimulated with inflammatory medium. The cell invasion ability were evaluated through wound healing assay and transwell invasion assay. The expression levels of EMT-related proteins, LGR5, and p-YAP were detected by real time PCR, western blotting, and immunofluorescence. The results showed that LGR5 expression and the EMT process were significantly enhanced under inflammatory condition. The expression of EMT-related proteins was up-regulated, while that of p-YAP was decreased. After inhibiting the high LGR5 expression with short interfering RNA, the expression of EMT-related proteins was also down-regulated, while that of p-YAP was significantly increased. The use of verteporfin (VP), an inhibitor of YAP activity that promotes YAP phosphorylation, did not affect LGR5 expression. In conclusion, we suggest that the inflammatory condition leads to high LGR5 expression, which up-regulating the expression of EMT-related proteins by inhibiting the YAP phosphorylation.

Spatial modeling reveals nuclear phosphorylation and subcellular shuttling of YAP upon drug-induced liver injury

The Hippo signaling pathway controls cell proliferation and tissue regeneration via its transcriptional effectors yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ). The canonical pathway topology is characterized by sequential phosphorylation of kinases in the cytoplasm that defines the subcellular localization of YAP and TAZ. However, the molecular mechanisms controlling the nuclear/cytoplasmic shuttling dynamics of both factors under physiological and tissue-damaging conditions are poorly understood. By implementing experimental in vitro data, partial differential equation modeling, as well as automated image analysis, we demonstrate that nuclear phosphorylation contributes to differences between YAP and TAZ localization in the nucleus and cytoplasm. Treatment of hepatocyte-derived cells with hepatotoxic acetaminophen (APAP) induces a biphasic protein phosphorylation eventually leading to nuclear protein enrichment of YAP but not TAZ. APAP-dependent regulation of nuclear/cytoplasmic YAP shuttling is not an unspecific cellular response but relies on the sequential induction of reactive oxygen species (ROS), RAC-alpha serine/threonine-protein kinase (AKT, synonym: protein kinase B), as well as elevated nuclear interaction between YAP and AKT. Mouse experiments confirm this sequence of events illustrated by the expression of ROS-, AKT-, and YAP-specific gene signatures upon APAP administration. In summary, our data illustrate the importance of nuclear processes in the regulation of Hippo pathway activity. YAP and TAZ exhibit different shuttling dynamics, which explains distinct cellular responses of both factors under physiological and tissue-damaging conditions.

YAP Overexpression in Breast Cancer Cells Promotes Angiogenesis through Activating YAP Signaling in Vascular Endothelial Cells

Purpose. The YAP signaling pathway is altered and implicated as oncogenic in human mammary cancers. However, roles of YAP signaling that regulate the breast tumor angiogenesis have remained elusive. Tumor angiogenesis is coordinated by the activation of both cancer cells and vascular endothelial cells. Whether the YAP signaling pathway can regulate the intercellular interaction between cancer cells and endothelial cells is essentially unknown. Methods. The effects of YAP on tumor angiogenesis, migration, and proliferation of vascular endothelial cells were evaluated in vitro. Expression of proteins and phosphorylating proteins involved in YAP, G13-RhoA, and PI3K/Akt signaling pathways was evaluated using the Western blotting, immunofluorescence staining, and immunohistochemistry analysis. In addition, the effects of YAP on breast cancer angiogenesis were evaluated in vivo by tumor xenograft mice. Results. We showed here that conditioned media from YAP overexpressed breast cancer cells (CM-YAP+) could promote angiogenesis, accompanied by increased tube formation, migration, and proliferation of human umbilical vein endothelial cells (HUVECs). Down regulation of YAP in HUVECs reversed CM-YAP+ induced angiogenesis. CM-YAP+ time-dependently activated YAP in HUVECs by dephosphorylating YAP and increasing nuclear translocation. We also identified that both G13-RhoA and PI3K/Akt signaling pathway were necessary for CM-YAP+ induced activation of YAP. Besides, connective tissue growth factor (CTGF) and angiopoietin-2 (ANG-2) acted as down-stream of YAP in HUVECs to promote angiogenesis. In addition, subcutaneous tumors nude mice model demonstrated that tumors overexpressed YAP revealed more neovascularization in vivo. Conclusion. YAP-YAP interaction between breast cancer cells and endothelial cells could promote tumor angiogenesis, supporting that YAP is a potential marker and target for developing novel therapeutic strategies against breast cancer.

The molecular mechanisms and targeting strategies of transcription factors in cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma consists of a cluster of malignant biliary tumors that tend to have a poor prognosis, ranking as the second most prevalent type of liver cancer, and their incidence rate has increased globally recently. The high-frequency driving mutations of cholangiocarcinoma, such as KRAS/IDH1/ARID1A/P53, imply the epigenetic instability of cholangiocarcinoma, leading to the dysregulation of various related transcription factors, thus affecting the occurrence and development of cholangiocarcinoma. Increasingly evidence indicates that the high heterogeneity and malignancy of cholangiocarcinoma are closely related to the dysregulation of transcription factors which promote cell proliferation, invasion, migration, angiogenesis, and drug resistance through reprogrammed transcriptional networks. It is of great significance to further explore and summarize the role of transcription factors in cholangiocarcinoma.

AREAS COVERED

This review summarizes the oncogenic or tumor suppressive roles of key transcription factors in regulating cholangiocarcinoma progression and the potential targeting strategies of transcription factors in cholangiocarcinoma.

EXPERT OPINION

Cholangiocarcinoma is a type of cancer highly influenced by transcriptional regulation, specifically transcription factors and epigenetic regulatory factors. Targeting transcription factors could be a potential and important strategy that is likely to impact future cholangiocarcinoma treatment.

The Molecular Pathogenesis and Targeted Therapies for Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a group of malignancies of the bile ducts with high mortality rates and limited treatment options. In the past decades, remarkable efforts have been dedicated toward elucidating the specific molecular signaling pathways and oncogenic loops driving cholangiocarcinogenesis to ultimately develop more effective therapies. Despite some recent advances, an extensive intra- and inter-tumor heterogeneity together with a poorly understood immunosuppressive microenvironment significantly compromises the efficacy of available treatments. Here, we provide a concise review of the latest advances and current knowledge of the molecular pathogenesis of CCA focusing on clinically relevant aberrations as well as future research avenues.

Advances in prognostic and therapeutic targets for hepatocellular carcinoma and intrahepatic cholangiocarcinoma: The hippo signaling pathway

Primary liver cancer is the sixth most frequently diagnosed cancer worldwide and the third leading cause of cancer-related death. The majority of the primary liver cancer cases are hepatocellular carcinoma and intrahepatic cholangiocarcinoma. Worldwide, there is an increasing incidence of primary liver cancer cases due to multiple risk factors ranging from parasites and viruses to metabolic diseases and lifestyles. Often, patients are diagnosed at advanced stages, depriving them of surgical curability benefits. Moreover, the efficacy of the available chemotherapeutics is limited in advanced stages. Furthermore, tumor metastases and recurrence make primary liver cancer management exceptionally challenging. Thus, exploring the molecular mechanisms for the development and progression of primary liver cancer is critical in improving diagnostic, treatment, prognostication, and surveillance modalities. These mechanisms facilitate the discovery of specific targets that are critical for novel and more efficient treatments. Consequently, the Hippo signaling pathway executing a pivotal role in organogenesis, hemostasis, and regeneration of tissues, regulates liver cells proliferation, and apoptosis. Cell polarity or adhesion molecules and cellular metabolic status are some of the biological activators of the pathway. Thus, understanding the mechanisms exhibited by the Hippo pathway is critical to the development of novel targeted therapies. This study reviews the advances in identifying therapeutic targets and prognostic markers of the Hippo pathway for primary liver cancer in the past six years.

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.

The regulation of yes-associated protein/transcriptional coactivator with PDZ-binding motif and their roles in vascular endothelium

Normal endothelial function plays a pivotal role in maintaining cardiovascular homeostasis, while endothelial dysfunction causes the occurrence and development of cardiovascular diseases. Yes-associated protein (YAP) and its homolog transcriptional co-activator with PDZ-binding motif (TAZ) serve as crucial nuclear effectors in the Hippo signaling pathway, which are regulated by mechanical stress, extracellular matrix stiffness, drugs, and other factors. Increasing evidence supports that YAP/TAZ play an important role in the regulation of endothelial-related functions, including oxidative stress, inflammation, and angiogenesis. Herein, we systematically review the factors affecting YAP/TAZ, downstream target genes regulated by YAP/TAZ and the roles of YAP/TAZ in regulating endothelial functions, in order to provide novel potential targets and effective approaches to prevent and treat cardiovascular diseases.

DLGAP1-AS2-Mediated Phosphatidic Acid Synthesis Activates YAP Signaling and Confers Chemoresistance in Squamous Cell Carcinoma

Squamous cell carcinomas (SCC) constitute a group of human malignancies that originate from the squamous epithelium. Most SCC patients experience treatment failure and relapse and have a poor prognosis due to de novo and acquired resistance to first-line chemotherapeutic agents. To identify chemoresistance mechanisms and explore novel targets for chemosensitization, we performed whole-transcriptome sequencing of paired resistant and parental SCC cells. We identified DLGAP1 antisense RNA 2 (D-AS2) as a crucial noncoding RNA that contributes to chemoresistance in SCC. Mechanistically, D-AS2 affected chromatin accessibility around the histone mark H3K27ac of FAM3 metabolism regulating signaling molecule D (FAM3D), reducing FAM3D mRNA transcription and extracellular protein secretion. FAM3D interacted with the Gαi-coupled G protein-coupled receptors (GPCRs) formyl peptide receptor 1 (FPR1) and FPR2 to suppress phospholipase D (PLD) activity, and reduced FAM3D increased PLD signaling. Moreover, activated PLD promoted phosphatidic acid (PA) production and subsequent nuclear translocation of yes-associated protein (YAP). Accordingly, in vivo administration of a D-AS2-targeting antisense oligonucleotide sensitized SCC to cisplatin treatment. In summary, this study shows that D-AS2/FAM3D-mediated PLD/PA lipid signaling is essential for SCC chemoresistance, suggesting D-AS2 can be targeted to sensitize SCC to cytotoxic chemotherapeutic agents.

YAP1 is essential for malignant mesothelioma tumor maintenance

Malignant pleural mesothelioma, a tumor arising from the membrane covering the lungs and the inner side of the ribs, is a cancer in which genetic alterations of genes encoding proteins that act on or are part of the Hippo-YAP1 signaling pathway are frequent. Dysfunctional Hippo signaling may result in aberrant activation of the transcriptional coactivator protein YAP1, which binds to and activates transcription factors of the TEAD family. Recent studies have associated elevated YAP1 protein activity with a poor prognosis of malignant mesothelioma and its resistance to current therapies, but its role in tumor maintenance is unclear. In this study, we investigate the dependence of malignant mesothelioma on YAP1 signaling to maintain fully established tumors in vivo. We show that downregulation of YAP1 in a dysfunctional Hippo genetic background results in the inhibition of YAP1/TEAD-dependent gene expression, the induction of apoptosis, and the inhibition of tumor cell growth in vitro. The conditional downregulation of YAP1 in established tumor xenografts leads to the inhibition of YAP1-dependent gene transcription and eventually tumor regression. This effect is only seen in the YAP1-activated MSTO-211H mesothelioma xenograft model, but not in the Hippo-independent HCT116 colon cancer xenograft model. Our data demonstrate that, in the context of a Hippo pathway mutated background, YAP1 activity alone is enough to maintain the growth of established tumors in vivo, thus validating the concept of inhibiting the activated YAP1-TEAD complex for the treatment of malignant pleural mesothelioma patients.

The biology of YAP in programmed cell death

In the last few decades, YAP has been shown to be critical in regulating tumor progression. YAP activity can be regulated by many kinase cascade pathways and proteins through phosphorylation and promotion of cytoplasmic localization. Other factors can also affect YAP activity by modulating its binding to different transcription factors (TFs). Programmed cell death (PCD) is a genetically controlled suicide process present with the scope of eliminating cells unnecessary or detrimental for the proper development of the organism. In some specific states, PCD is activated and facilitates the selective elimination of certain types of tumor cells. As a candidate oncogene correlates with many regulatory factors, YAP can inhibit or induce different forms of PCD, including apoptosis, autophagy, ferroptosis and pyroptosis. Furthermore, YAP may act as a bridge between different forms of PCD, eventually leading to different outcomes regarding tumor development. Researches on YAP and PCD may benefit the future development of novel treatment strategies for some diseases. Therefore, in this review, we provide a general overview of the cellular functions of YAP and the relationship between YAP and PCD.

Long intergenic non-protein-coding RNA 467 promotes tumor progression and angiogenesis via the microRNA-128-3p/vascular endothelial growth factor C axis in colorectal cancer

Long non-coding RNAs (lncRNAs) are important regulators and biomarkers of tumorigenesis and tumor metastasis. Long intergenic non-protein-coding RNA 467 (LINC00467) is associated with various cancers. However, the role and mechanism of LINC00467 in colorectal cancer (CRC) promotion are poorly understood. This study aimed to present new details of LINC00467 in the progression of CRC. Reverse transcription–polymerase chain reaction demonstrated that the expression level of LINC00467 in CRC tissues and cell lines was significantly upregulated, which was closely related to the clinical features of CRC. Cell and animal studies showed that the downregulation of LINC00467 expression in CRC cells significantly inhibited cell proliferation, metastasis, and angiogenesis. Moreover, the overexpression of LINC00467 accelerated CRC promotion. Bioinformatics analysis and luciferase reporter assay confirmed that LINC00467 binds to miR-128-3p. Rescue experiments manifested that decreased miR-128-3p level reversed CRC cell inhibition by silencing LINC00467. Furthermore, vascular endothelial growth factor C (VEGFC) was identified as a target of miR-128-3p that could reverse the inhibition of cell growth that is mediated by miR-128-3p. Altogether, our results showed that LINC00467 contributes to CRC progression and angiogenesis via the miR-128-3p/VEGFC axis. Our findings expand the understanding of the mechanisms underlying CRC and suggest potential targets for clinical strategies against CRC.

Effect of TDP43-CTFs35 on Brain Endothelial Cell Functions in Cerebral Ischemic Injury

Pathological changes in the brain endothelium play an important role in the progression of ischemic stroke and the compromised BBB under ischemic stroke conditions cause neuronal damage. However, the pathophysiological mechanisms of the BBB under normal conditions and under ischemic stroke conditions have not been fully elucidated. The present study demonstrated that knockdown of TAR DNA-binding protein 43 (TDP-43) or overexpression of TDP43-CTFs35 inhibited tight junction protein expression, and mammalian sterile-20-like 1/2 (MST1/2) and YES-associated protein (YAP) phosphorylation in brain ECs and suppressed brain EC migration in vitro. The cytoplasmic TDP43-CTFs35 level was increased in brain ECs 24 h and 72 h after MCAO, but it disappeared 1 week after cerebral ischemia. The expression of tight junction proteins was also significantly deceased 24 h after MCAO and then gradually recovered at 72 h and 1 week after MCAO. The level of YAP phosphorylation was first significantly decreased 24 h after MCAO and then increased 72 h and 1 week after MCAO, accompanied by nuclear YAP translocation. The underlying mechanism is TDP43-CTFs35-mediated inhibition of Hippo signaling pathway activity through the dephosphorylation of MST1/2, which leads to the inhibition of YAP phosphorylation and the subsequent impairment of brain EC migration and tight junction protein expression. This study provides new insights into the mechanisms of brain vascular EC regulation, which may impact on BBB integrity after cerebral ischemic injury.

Hippo signalling in the liver: role in development, regeneration and disease

The Hippo signalling pathway has emerged as a major player in many aspects of liver biology, such as development, cell fate determination, homeostatic function and regeneration from injury. The regulation of Hippo signalling is complex, with activation of the pathway by diverse upstream inputs including signals from cellular adhesion, mechanotransduction and crosstalk with other signalling pathways. Pathological activation of the downstream transcriptional co-activators yes-associated protein 1 (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ, encoded by WWTR1), which are negatively regulated by Hippo signalling, has been implicated in multiple aspects of chronic liver disease, such as the development of liver fibrosis and tumorigenesis. Thus, development of pharmacological inhibitors of YAP-TAZ signalling has been an area of great interest. In this Review, we summarize the diverse roles of Hippo signalling in liver biology and highlight areas where outstanding questions remain to be investigated. Greater understanding of the mechanisms of Hippo signalling in liver function should help facilitate the development of novel therapies for the treatment of liver disease.

Overcome Drug Resistance in Cholangiocarcinoma: New Insight Into Mechanisms and Refining the Preclinical Experiment Models

Cholangiocarcinoma (CCA) is an aggressive tumor characterized by a poor prognosis. Therapeutic options are limited in patients with advanced stage of CCA, as a result of the intrinsic or acquired resistance to currently available chemotherapeutic agents, and the lack of new drugs entering into clinical application. The challenge in translating basic research to the clinical setting, caused by preclinical models not being able to recapitulate the tumor characteristics of the patient, seems to be an important reason for the lack of effective and specific therapies for CCA. So, there seems to be two ways to improve patient outcomes. The first one is developing the combination therapies based on a better understanding of the mechanisms contributing to the resistance to currently available chemotherapeutic agents. The second one is developing novel preclinical experimental models that better recapitulate the genetic and histopathological features of the primary tumor, facilitating the screening of new drugs for CCA patients. In this review, we discussed the evidence implicating the mechanisms underlying treatment resistance to currently investigated drugs, and the development of preclinical experiment models for CCA.

Regorafenib inhibits epithelial-mesenchymal transition and suppresses cholangiocarcinoma metastasis via YAP1-AREG axis

Cholangiocarcinoma (CCA) is a subtype of bile duct cancer usually diagnosed late with a low survival rate and no satisfactorily systemic treatment. Recently, regorafenib has been accepted as a second-line treatment for CCA patients. In this study, we investigated the potential signal transduction pathways mediated by regorafenib. We established a transcriptomic database for regorafenib-treated CCA cells using expression microarray chips. Our data indicate that regorafenib inhibits yes-associated protein 1 (YAP1) activity in various CCA cells. In addition, we demonstrated that YAP1 regulates epithelial-mesenchymal transition (EMT)-related genes, including E-cadherin and SNAI2. We further examined YAP1 activity, phosphorylation status, and expression levels of YAP1 downstream target genes in the regorafenib model. We found that regorafenib dramatically suppressed these events in CCA cells. Moreover, in vivo results revealed that regorafenib could significantly inhibit lung foci formation and tumorigenicity. Most importantly, regorafenib and amphiregulin (AREG) neutralize antibody exhibited synergistic effects against CCA cells. In a clinical setting, patients with high YAP1 and EMT expression had a worse survival rate than patients with low YAP1, and EMT expression did. In addition, we found that YAP1 upregulated the downstream target amphiregulin in CCA. Our findings suggest that AREG neutralizing antibody antibodies combined with regorafenib can reverse the CCA metastatic phenotype and EMT in vitro and in vivo. These findings provide novel therapeutic strategies to combat the metastasis of CCA.

USP49 mediates tumor progression and poor prognosis through a YAP1-dependent feedback loop in gastric cancer

The importance of the Hippo-Yes-associated protein 1 (YAP1) pathway in gastric carcinogenesis and metastasis has attracted considerable research attention; however, the regulatory network of YAP1 in gastric cancer (GC) is not completely understood. In this study, ubiquitin-specific peptidase 49 (USP49) was identified as a novel deubiquitinase of YAP1, knockdown of USP49 inhibited the proliferation, metastasis, chemoresistance, and peritoneal metastasis of GC cells. Overexpression of USP49 showed opposing biological effects. Moreover, USP49 was transcriptionally activated by the YAP1/TEAD4 complex, which formed a positive feedback loop with YAP1 to promote the malignant progression of GC cells. Finally, we collected tissue samples and clinical follow-up information from 482 GC patients. The results showed that USP49 expression was high in GC cells and positively correlated with the expression of YAP1 and its target genes, connective tissue growth factor (CTGF) and cysteine-rich angiogenic inducer 61 (CYR61). Survival and Cox regression analysis showed that high USP49 expression was associated with poor prognosis and was an independent prognostic factor. Moreover, patients with high USP49 and YAP1 expression had extremely short overall survival. The findings of this study reveal that the aberrant activation of the USP49/YAP1 positive feedback loop plays a critical role in the malignant progression of GC, thus providing potential novel prognostic factors and therapeutic targets for GC.

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.