Connective tissue growth factor autocriny in human hepatocellular carcinoma: oncogenic role and regulation by epidermal growth factor receptor/yes-associated protein-mediated activation

Exosome-mediated transfer of circRNA563 promoting hepatocellular carcinoma by targeting the microRNA148a-3p/metal-regulatory transcription factor-1 pathway

BACKGROUND

Mesenchymal stem cells (MSCs) exert anti-oncogenic effects via exosomes containing non-coding RNA (ncRNA), which play important roles in tumor biology. Our preliminary study identified the interaction of the ncRNA hsa_circ_0000563 (circ563) and the circ563-associated miR-148a-3p in exosomes, as miR-148a-3p and its target metal-regulatory transcription factor-1 (MTF-1) are implicated in hepatocellular carcinoma (HCC) progression.

AIM

To identify the clinical significance, functional implications, and mechanisms of circ563 in HCC.

METHODS

The expression levels of miR-148a-3p and MTF-1 in exosomes derived from MSC and HCC cells were compared, and their effects on HCC cells were assessed. Using a dual-luciferase reporter assay, miR-148a-3p was identified as an associated microRNA of circ563, whose role in HCC regulation was assessed in vitro and in vivo.

RESULTS

The silencing of circ563 blocked the HCC cell proliferation and invasion and induced apoptosis. Co-culturing of HCC cells with MSC-derived exosomes following circ563 overexpression promoted cell proliferation and metastasis and elicited changes in miR-148a-3p and MTF-1 expression. The tumor-promoting effects of circ563 were partially suppressed by miR-148a-3p overexpression or MTF-1 depletion. Xenograft experiments performed in nude mice confirmed that circ563-enriched exosomes facilitated tumor growth by upregulating the expression of MTF-1. In HCC tissues, circ563 expression was negatively correlated with miR-148a-3p expression but positively correlated with MTF-1 levels.

CONCLUSION

MSCs may exhibit anti-HCC activity through the exosomal circ563/miR-148a-3p/MTF-1 pathway, while exosomes can transmit circ563 to promote oncogenic behavior by competitively binding to miR-148a-3p to activate MTF-1.

Unraveling Connective Tissue Growth Factor as a Therapeutic Target and Assessing Kahweol as a Potential Drug Candidate in Triple-Negative Breast Cancer Treatment

Triple-negative breast cancer (TNBC) is characterized by aggressive behavior and limited treatment options, necessitating the identification of novel therapeutic targets. In this study, we investigated the clinical significance of connective tissue growth factor (CTGF) as a prognostic marker and explored the potential therapeutic effects of kahweol, a coffee diterpene molecule, in TNBC treatment. Initially, through a survival analysis on breast cancer patients from The Cancer Genome Atlas (TCGA) database, we found that CTGF exhibited significant prognostic effects exclusively in TNBC patients. To gain mechanistic insights, we performed the functional annotation and gene set enrichment analyses, revealing the involvement of CTGF in migratory pathways relevant to TNBC treatment. Subsequently, in vitro experiments using MDA-MB 231 cells, a representative TNBC cell line, demonstrated that recombinant CTGF (rCTGF) administration enhanced cell motility, whereas CTGF knockdown using CTGF siRNA resulted in reduced motility. Notably, rCTGF restored kahweol-reduced cell motility, providing compelling evidence for the role of CTGF in mediating kahweol's effects. At the molecular level, kahweol downregulated the protein expression of CTGF as well as critical signaling molecules, such as p-ERK, p-P38, p-PI3K/AKT, and p-FAK, associated with cell motility. In summary, our findings propose CTGF as a potential prognostic marker for guiding TNBC treatment and suggest kahweol as a promising antitumor compound capable of regulating CTGF expression to suppress cell motility in TNBC. These insights hold promise for the development of targeted therapies and improved clinical outcomes for TNBC patients.

Role of the YAP/TAZ-TEAD Transcriptional Complex in the Metabolic Control of TRAIL Sensitivity by the Mevalonate Pathway in Cancer Cells

Different studies have reported that inhibiting the mevalonate pathway with statins may increase the sensitivity of cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), although the signaling mechanism leading to this sensitization remains largely unknown. We investigated the role of the YAP (Yes-associated protein)/TAZ (transcriptional co-activator with PDZ-binding motif)-TEAD (TEA/ATTS domain) transcriptional complex in the metabolic control of TRAIL sensitivity by the mevalonate pathway. We show that depleting nuclear YAP/TAZ in tumor cells, either via treatment with statins or by silencing YAP/TAZ expression with siRNAs, facilitates the activation of apoptosis by TRAIL. Furthermore, the blockage of TEAD transcriptional activity either pharmacologically or through the ectopic expression of a disruptor of the YAP/TAZ interaction with TEAD transcription factors, overcomes the resistance of tumor cells to the induction of apoptosis by TRAIL. Our results show that the mevalonate pathway controls cellular the FLICE-inhibitory protein (cFLIP) expression in tumor cells. Importantly, inhibiting the YAP/TAZ-TEAD signaling pathway induces cFLIP down-regulation, leading to a marked sensitization of tumor cells to apoptosis induction by TRAIL. Our data suggest that a combined strategy of targeting TEAD activity and selectively activating apoptosis signaling by agonists of apoptotic TRAIL receptors could be explored as a potential therapeutic approach in cancer treatment.

Cancer Stem Cell and Hepatic Stellate Cells in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common liver cancer. It is highly lethal and has high recurrence. Death among HCC patients occur mainly due to tumor progression, recurrence, metastasis, and chemoresistance. Cancer stem cells (CSCs) are cell subpopulations within the tumor that promote invasion, recurrence, metastasis, and drug resistance. Hepatic stellate cells (HSCs) are important components of the tumor microenvironment (TME) responsible for primary secretory ECM proteins during liver injury and inflammation. These cells promote fibrogenesis, infiltrate the tumor stroma, and contribute to HCC development. Interactions between HSC and CSC and their microenvironment help promote carcinogenesis through different mechanisms. This review summarizes the roles of CSCs and HSCs in establishing the TME in primary liver tumors and describes their involvement in HCC chemoresistance.

Micro RNA-411 Expression Improves Cardiac Phenotype Following Myocardial Infarction in Mice

Induction of endogenous regenerative capacity has emerged as one promising approach to repair damaged hearts following myocardial infarction (MI). Re-expression of factors that are exclusively expressed during embryonic development may reactivate the ability of adult cardiomyocytes to regenerate. Here, we identified miR-411 as a potent inducer of cardiomyocyte proliferation. Overexpression of miR-411 in the heart significantly increased cardiomyocyte proliferation and survival in a model MI. We found that miR-411 enhances the activity of YAP, the main downstream effector of the Hippo pathway, in cardiomyocytes. In conclusion, miR-411 induces cardiomyocyte regeneration and improves cardiac function post-MI likely by modulating the Hippo/YAP pathway.

U1A is a positive regulator of the expression of heterologous and cellular genes involved in cell proliferation and migration

Here, we show that direct recruitment of U1A to target transcripts can increase gene expression. This is a new regulatory role, in addition to previous knowledge showing that U1A decreases the levels of U1A mRNA and other specific targets. In fact, genome-wide, U1A more often increases rather than represses gene expression and many U1A-upregulated transcripts are directly bound by U1A according to individual nucleotide resolution crosslinking and immunoprecipitation (iCLIP) studies. Interestingly, U1A-mediated positive regulation can be transferred to a heterologous system for biotechnological purposes. Finally, U1A-bound genes are enriched for those involved in cell cycle and adhesion. In agreement with this, higher U1A mRNA expression associates with lower disease-free survival and overall survival in many cancer types, and U1A mRNA levels positively correlate with those of some oncogenes involved in cell proliferation. Accordingly, U1A depletion leads to decreased expression of these genes and the migration-related gene CCN2/CTGF, which shows the strongest regulation by U1A. A decrease in U1A causes a strong drop in CCN2 expression and CTGF secretion and defects in the expression of CTGF EMT targets, cell migration, and proliferation. These results support U1A as a putative therapeutic target for cancer treatment. In addition, U1A-binding sequences should be considered in biotechnological applications.

Functions of Yes-association protein (YAP) in cancer progression and anticancer therapy resistance

The Hippo pathway, a highly conserved kinase cascade, regulates cell proliferation, apoptosis, organ size, and tissue homeostasis. Dysregulation of this pathway reportedly plays an important role in the progression of various human cancers. Yes-association protein (YAP), the Hippo pathway’s core effector, is considered a marker for cancer therapy and patient prognosis. In addition, studies have indicated that YAP is involved in promoting anticancer drug resistance. This review summarizes current knowledge on YAP’s role in cancer progression, anticancer drug resistance, and advances in the development of YAP-targeting drugs. A thorough understanding of the complex interactions among molecular, cellular, and environmental factors concerning YAP function in cancer progression may provide new insight into the underlying mechanism of anticancer drug resistance. It might lead to improved prognosis through novel combined therapies.

Age-related downregulation of CCN2 is regulated by cell size in a YAP/TAZ-dependent manner in human dermal fibroblasts: impact on dermal aging

CCN2, a member of the CCN family of matricellular proteins, is a key mediator and biomarker of tissue fibrosis. We previously reported that CCN2 is significantly reduced in aged human dermis, which contributes to dermal aging through the downregulation of collagen production, the major structural protein in the skin. In this study, we investigated the underlying mechanisms of the age-related downregulation of CCN2 in human skin dermal fibroblasts. Dermal fibroblasts isolation and laser-capture microdissection‒coupled RT-PCR from human skin confirmed that age-related reduction of CCN2 expression is regulated by epigenetics. Mechanistic investigation revealed that age-related reduction of CCN2 is regulated by impaired dermal fibroblast spreading/cell size, which is a prominent feature of aged dermal fibroblasts in vivo. Gain-of-function and loss-of-function analysis confirmed that age-related downregulation of CCN2 is regulated by YAP/TAZ in response to reduced cell size. We further confirmed that restoration of dermal fibroblast size rapidly reversed the downregulation of CCN2 in a YAP/TAZ-dependent manner. Finally, we confirmed that reduced YAP/TAZ nuclear staining is accompanied by loss of CCN2 in aged human skin in vivo. Our data reveal a mechanism by which age-related reduction in fibroblast spreading/size drives YAP/TAZ-dependent downregulation of CCN2 expression, which in turn contributes to loss of collagen in aged human skin.

Emerging Molecular Dependencies of Mutant EGFR-Driven Non-Small Cell Lung Cancer

Epidermal growth factor receptor (EGFR) mutations are the molecular driver of a subset of non-small cell lung cancers (NSCLC); tumors that harbor these mutations are often dependent on sustained oncogene signaling for survival, a concept known as “oncogene addiction”. Inhibiting EGFR with tyrosine kinase inhibitors has improved clinical outcomes for patients; however, successive generations of inhibitors have failed to prevent the eventual emergence of resistance to targeted agents. Although these tumors have a well-established dependency on EGFR signaling, there remain questions about the underlying genetic mechanisms necessary for EGFR-driven oncogenesis and the factors that allow tumor cells to escape EGFR dependence. In this review, we highlight the latest findings on mutant EGFR dependencies, co-operative drivers, and molecular mechanisms that underlie sensitivity to EGFR inhibitors. Additionally, we offer perspective on how these discoveries may inform novel combination therapies tailored to EGFR mutant NSCLC.

YAP-induced Ccl2 expression is associated with a switch in hepatic macrophage identity and vascular remodelling in liver cancer

BACKGROUND & AIM

The development of hepatocellular carcinoma (HCC) is associated with the formation of communication networks leading to the recruitment of disease-modifying macrophages. However, how oncogenes in tumour cells control paracrine communication is not fully understood.

METHODS

Transgenic mice with liver-specific expression of the constitutively active yes-associated protein (YAP^S127A ) or an orthotopic implantation model served as tumour models. FACS-sorted F4/80⁺ /CD11b^dim /CD146^- /retinoid^- macrophages from healthy and tumour-bearing livers were used for transcriptomic profiling. Expression data of 242 human HCCs and a tissue microarray consisting of 91 HCCs and seven liver tissues were analyzed.

RESULTS

Screening of primary tumour cells expressing YAP^S127A identified CC chemokine ligand 2 (Ccl2) as a macrophage chemoattractant, whose expression was regulated in a YAP/TEA domain family member 4 (TEAD4)-dependent manner. Ccl2 expression was associated with a loss of Kupffer cells (KCs) and an increase in immature macrophages (Mɸ^imm ) in hepatocarcinogenesis. Recruited Mɸ^imm were characterized by a lack of functional polarization (M0 signature) and high expression of the Ccl2 receptors C-C motif chemokine receptor 2 (Ccr2), C-X3-C motif chemokine receptor 1 (Cx3cr1) and pro-angiogenic platelet-derived growth factors (Pdgfa/Pdgfb). Mɸ^imm formed cellular clusters in the perivascular space, which correlated with vascular morphometric changes indicative for angiogenesis. In human HCCs, the M0 signature served as an identifier for poor clinical outcome and CCL2 correlated with YAP expression and vascular network formation.

CONCLUSIONS

In conclusion, YAP/TEAD4-regulated Ccl2 associates with perivascular recruitment of unpolarized Mɸ^imm and may contribute to a proangiogenic microenvironment in liver cancer.

Mechano-Signaling Aspects of Hepatocellular Carcinoma

HCC is one of the leading causes of cancer related death worldwide and comprises about 90% of the cases of primary liver cancer. It is generally accompanied by chronic liver fibrosis characterised by deposition of collagen fibres, which, in turn, causes enhanced stiffness of the liver tissue. Changes of tissue stiffness give rise to alterations of signalling pathways that are associated to mechanical properties of the cells and the extracellular matrix, and that can be subsumed as "mechano-signaling pathways", like, e.g., the YAP/TAZ pathway, or the SRF pathway. Stiffness of the liver tissue modulates mechanical regulation of many genes involved in HCC progression. However, mechano-signaling is still rather underrepresented in our concepts of cancer in comparison to "classical" biochemical signalling pathways. This review aims to give an overview of various stiffness induced mechano-biological aspects of HCC.

Cav1/EREG/YAP Axis in the Treatment Resistance of Cav1-Expressing Head and Neck Squamous Cell Carcinoma

Simple Summary

The EGFR-targeting antibody cetuximab (CTX) combined with radiotherapy has been proven effective for the treatment of locally advanced head and neck squamous cell carcinoma (LA-HNSCC). Due to resistance to CTX, some patients do not benefit from the treatment and recurrence is observed. As caveolin-1 (Cav1) has been reported to affect the EGFR pathway, we aimed to elucidate how it might affect the response to CTX-radiotherapy. We showed that Cav1 expression conferred surviving, growing and motile capacities that protect cells against the combination of CTX-radiotherapy. The protecting effects of Cav1 are mediated by the Cav1/EREG/YAP axis. We also showed in a retrospective study that a high expression of Cav1 was predictive of locoregional relapse of LA-HNSCC. Cav1 should be taken into consideration in the future as a prognosis marker to identify the subgroup of advanced HNSCC at higher risk of recurrence, but also to help clinicians to choose the more appropriate therapeutic strategies.

Abstract

The EGFR-targeting antibody cetuximab (CTX) combined with radiotherapy is the only targeted therapy that has been proven effective for the treatment of locally advanced head and neck squamous cell carcinoma (LA-HNSCC). Recurrence arises in 50% of patients with HNSCC in the years following treatment. In clinicopathological practice, it is difficult to assign patients to classes of risk because no reliable biomarkers are available to predict the outcome of HPV-unrelated HNSCC. In the present study, we investigated the role of Caveolin-1 (Cav1) in the sensitivity of HNSCC cell lines to CTX-radiotherapy that might predict HNSCC relapse. Ctrl- and Cav-1-overexpressing HNSCC cell lines were exposed to solvent, CTX, or irradiation, or exposed to CTX before irradiation. Growth, clonogenicity, cell cycle progression, apoptosis, metabolism and signaling pathways were analyzed. Cav1 expression was analyzed in 173 tumor samples and correlated to locoregional recurrence and overall survival. We showed that Cav1-overexpressing cells demonstrate better survival capacities and remain proliferative and motile when exposed to CTX-radiotherapy. Resistance is mediated by the Cav1/EREG/YAP axis. Patients whose tumors overexpressed Cav1 experienced regional recurrence a few years after adjuvant radiotherapy ± chemotherapy. Together, our observations suggest that a high expression of Cav1 might be predictive of locoregional relapse of LA-HNSCC.

Advances of Fibroblast Growth Factor/Receptor Signaling Pathway in Hepatocellular Carcinoma and its Pharmacotherapeutic Targets

Hepatocellular carcinoma (HCC) is a type of primary liver cancer with poor prognosis, and its incidence and mortality rate are increasing worldwide. It is refractory to conventional chemotherapy and radiotherapy owing to its high tumor heterogeneity. Accumulated genetic alterations and aberrant cell signaling pathway have been characterized in HCC. The fibroblast growth factor (FGF) family and their receptors (FGFRs) are involved in diverse biological activities, including embryonic development, proliferation, differentiation, survival, angiogenesis, and migration, etc. Data mining results of The Cancer Genome Atlas demonstrate high levels of FGF and/or FGFR expression in HCC tumors compared with normal tissues. Moreover, substantial evidence indicates that the FGF/FGFR signaling axis plays an important role in various mechanisms that contribute to HCC development. At present, several inhibitors targeting FGF/FGFR, such as multikinase inhibitors, specific FGFR4 inhibitors, and FGF ligand traps, exhibit antitumor activity in preclinical or early development phases in HCC. In this review, we summarize the research progress regarding the molecular implications of FGF/FGFR-mediated signaling and the development of FGFR-targeted therapeutics in hepatocarcinogenesis.

Histone Deacetylase Inhibitors in the Treatment of Hepatocellular Carcinoma: Current Evidence and Future Opportunities

Hepatocellular carcinoma (HCC) remains a major health problem worldwide with a continuous increasing prevalence. Despite the introduction of targeted therapies like the multi-kinase inhibitor sorafenib, treatment outcomes are not encouraging. The prognosis of advanced HCC is still dismal, underlying the need for novel effective treatments. Apart from the various risk factors that predispose to the development of HCC, epigenetic factors also play a functional role in tumor genesis. Histone deacetylases (HDACs) are enzymes that remove acetyl groups from histone lysine residues of proteins, such as the core nucleosome histones, in this way not permitting DNA to loosen from the histone octamer and consequently preventing its transcription. Considering that HDAC activity is reported to be up-regulated in HCC, treatment strategies with HDAC inhibitors (HDACIs) showed some promising results. This review focuses on the use of HDACIs as novel anticancer agents and explains the mechanisms of their therapeutic effects in HCC.

The YAP signaling pathway promotes the progression of lymphatic malformations through the activation of lymphatic endothelial cells

BACKGROUND

To investigate whether the YAP/TAZ (Yes-associated protein/transcriptional coactivator with PDZ binding motif) pathway contributes to the pathogenesis of lymphatic malformations (LMs).

METHODS

YAP, TAZ, CTGF (connective tissue growth factor), and Ki-67 were detected in LMs by immunohistochemistry. The colocalization of YAP and Ki-67 was analyzed by double immunofluorescence. Pearson's correlation and cluster analyses were performed to analyze the relationships between these proteins. Human dermal lymphatic endothelial cells (HDLECs) were used for mechanistic investigation. Rat models of LMs were established to investigate the role of the YAP pathway in LM development.

RESULTS

Compared with those in normal skin, the expression levels of YAP, TAZ, CTGF, and Ki-67 were significantly upregulated in lymphatic endothelial cells (LECs) of LMs. Interestingly, YAP and CTGF presented much higher expression levels in infected LMs. In experiments in vitro, lipopolysaccharide (LPS) enhanced the expression of YAP in a concentration- and time-dependent manner via the increased phosphorylation of Erk1/2 (extracellular signal-regulated kinase 1/2). Moreover, the proliferation, invasion, and tubule formation of HDLECs increased significantly in accordance with the activation of the YAP signaling pathway. Furthermore, LM rat models validated that LPS facilitated the development of LMs, which was dependent on the activation of YAP.

CONCLUSIONS

The data reveal that activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs.

IMPACT

Compared with that in normal skin, the YAP signaling pathway was activated in LECs of LMs. Inhibiting the YAP signaling pathway attenuated the proliferation, invasion, and tubule formation of HDLECs. Additionally, the activation of the YAP signaling pathway could promote LM development in a rat model. Activation of the YAP signaling pathway in LECs may play a crucial role in the progression of LMs. The YAP signaling pathway was activated in LMs. Inhibition of the YAP signaling pathway could promote regression of the lesions.

Hepatocyte nuclear factor 4α negatively regulates connective tissue growth factor during liver regeneration

Liver regeneration after injury requires fine-tune regulation of connective tissue growth factor (Ctgf). It also involves dynamic expression of hepatocyte nuclear factor (Hnf)4α, Yes-associated protein (Yap), and transforming growth factor (Tgf)-β. The upstream inducers of Ctgf, such as Yap, etc, are well-known. However, the negative regulator of Ctgf remains unclear. Here, we investigated the Hnf4α regulation of Ctgf post-various types of liver injury. Both wild-type animals and animals contained siRNA-mediated Hnf4α knockdown and Cre-mediated Ctgf conditional deletion were used. We observed that Ctgf induction was associated with Hnf4α decline, nuclear Yap accumulation, and Tgf-β upregulation during early stage of liver regeneration. The Ctgf promoter contained an Hnf4α binding sequence that overlapped with the cis-regulatory element for Yap and Tgf-β. Ctgf loss attenuated inflammation, hepatocyte proliferation, and collagen synthesis, whereas Hnf4α knockdown enhanced Ctgf induction and liver fibrogenesis. These findings provided a new mechanism about fine-tuned regulation of Ctgf through Hnf4α antagonism of Yap and Tgf-β activities to balance regenerative and fibrotic signals.

Insulin suppresses transcriptional activity of yes-associated protein in insulin target cells

Yes-associated protein (YAP), the main transcriptional coactivator of the Hippo pathway, integrates multiple inputs from different signaling cascades. Evidence implicates YAP in the control of cellular nutrient and energy status, but the underlying mechanisms are not fully elucidated. Here we show that insulin modulates YAP transcriptional activity in classic insulin target cells, namely HepG2 and C2C12. Insulin increases YAP phosphorylation and significantly decreases YAP abundance in HepG2 cell nuclei. Proximity ligation assay analysis revealed a marked reduction in the interaction of YAP with TEA domain (TEAD) transcription factors in the nuclei of insulin-exposed cells. Consistent with these findings, insulin impaired both YAP/TEAD-mediated transcription and transcription of YAP target genes in HepG2 and C2C12 cells. Serum starvation abrogated the effect of insulin on YAP phosphorylation and YAP transcription. Both the expression of two gluconeogenesis genes, G6PC and PCK1, and the inhibitory effect of insulin on these genes were attenuated in YAP-deficient HepG2 cells. Our results identify insulin as a previously undescribed suppressor of YAP activity in insulin target cells and provide insight into cross-talk between the insulin and Hippo pathways.

TGF-β induced chemoresistance in liver cancer is modulated by xenobiotic nuclear receptor PXR

Hepatocellular carcinoma appears as an extremely angiogenic solid tumor marked by apoptosis evasion, dysregulated cell cycle and low sensitivity to chemotherapy. TGF-β, a multifunctional cytokine, plays a pleiotropic role in the tumor microenvironment and has implications in cancer drug resistance. The current study provides novel evidence that TGF-β signaling contributes to drug resistance in liver cancer cells by inducing the expression of xenobiotic nuclear receptor PXR. We observed that PXR increases the expression of drug efflux transporters; therefore, accounting for exacerbated drug resistance. Additionally, anti-apoptotic nature of PXR contributes to TGF-β mediated chemoresistance as seen by procaspase-3 and Mcl-1 cellular levels. TGF-β binding to the TGF-β receptor triggers a complex downstream signaling cascade through a non-canonical SMAD-independent ERK pathway that leads to increased PXR expression. Activated ERK activates ETS1 transcription factor which is a critical regulator of endogenous PXR expression in hepatic cells. Loss of function of ETS1 abrogates the TGF-β induced PXR expression. Together these findings indicate that PXR modulates TGF-β induced resistance to chemotherapy in liver cancer cells. This underscores the need for combinatorial approaches with focus on PXR antagonism to improve drug effectiveness in hepatocellular carcinoma.Abbreviations: HCC: Hepatocellular Carcinoma; FDA: Food and Drug Administration; TGF-β: Transforming growth factor-β; PXR: Pregnane X receptor; CAR: Constitutive androstane receptor; P-gp/ABCB1: P-glycoproteins/ATP-binding cassette transporter subfamily B member 1; MRP1/ABCC1 and MRP2/ABCC2: Multidrug-resistance associated proteins; BCRP/ABCG2: Breast cancer resistant protein; DMEs: Drug-metabolizing enzymes; CFDA: 5,6-carboxyfluorescein diacetate; ETS1: Transcription factor E26 transformation specific sequence 1.

Verteporfin targeting YAP1/TAZ-TEAD transcriptional activity inhibits the tumorigenic properties of gastric cancer stem cells

Gastric carcinomas (GC) are heterogeneous tumors, composed of a subpopulation of cluster of differentiation-44 (CD44)+ tumorigenic and chemoresistant cancer stem cells (CSC). YAP1 and TAZ oncoproteins (Y/T) interact with TEA domain family member 1 (TEAD) transcription factors to promote cell survival and proliferation in multiple tissues. Their activity and role in GC remain unclear. This work aimed to analyze Y/T-TEAD activity and molecular signature in gastric CSC, and to assess the effect of verteporfin, a Food and Drug Administration-approved drug preventing Y/T-TEAD interaction, on gastric CSC tumorigenic properties. Y/T-TEAD molecular signature was investigated using bioinformatical (KmPlot database), transcriptomic and immunostaining analyses in patient-derived GC and cell lines. Verteporfin effects on Y/T-TEAD transcriptional activity, CSC proliferation and tumorigenic properties were evaluated using in vitro tumorsphere assays and mouse models of patient-derived GC xenografts. High expressions of YAP1, TAZ, TEAD1, TEAD4 and their target genes were associated with low overall survival in nonmetastatic human GC patients (n = 444). This Y/T-TEAD molecular signature was enriched in CD44+ patient-derived GC cells and in cells resistant to conventional chemotherapy. Verteporfin treatment inhibited Y/T-TEAD transcriptional activity, cell proliferation and CD44 expression, and decreased the pool of tumorsphere-forming CD44⁺ /aldehyde dehydrogenase (ALDH)^high gastric CSC. Finally, verteporfin treatment inhibited GC tumor growth in vivo; the residual tumor cells exhibited reduced expressions of CD44 and ALDH1, and more importantly, they were unable to initiate new tumorspheres in vitro. All these data demonstrate that Y/T-TEAD activity controls gastric CSC tumorigenic properties. The repositioning of verteporfin targeting YAP1/TAZ-TEAD activity could be a promising CSC-based strategy for the treatment of GC.

Down-regulation of interferon regulatory factor 2 binding protein 2 suppresses gastric cancer progression by negatively regulating connective tissue growth factor

Interferon regulatory factor 2 binding protein 2 (IRF2BP2) is a transcriptional repressor involved in regulating gene expression and other biological processes, including tumorigenesis. However, the clinical significance and roles of IRF2BP2 in human gastric cancer (GC) remain uncertain. Clinical GC tissues were obtained from GC patients at the First Affiliated Hospital of Nanchang University. Immunohistochemistry (IHC) was conducted to detect the IRF2BP2 protein in clinical paraffin specimens. Cell proliferation, migration and invasion were evaluated by MTT, colony formation assays and transwell assays. Co-immunoprecipitation was conducted to detect the interaction between TEA domain family members 4 (TEAD4) and vestigial-like family member 4 (VGLL4) or Yes-associated protein 1 (YAP1). Dual-luciferase reporter assay was used to confirm the binding of miR-101-3p to the 3'-UTR. The expression of IRF2BP2 was significantly higher in GC tissues than in normal tissues. Patients with higher IRF2BP2 protein expression had lower survival. IRF2BP2 knockdown inhibited proliferation, migration, invasion and epithelial-mesenchymal transition in GC cells. IRF2BP2 knockdown decreased the mRNA and protein levels of connective tissue growth factor (CTGF). The interaction between IRF2BP2 and VGLL4 increased the binding of TEAD4 to YAP1, resulting in the transcriptional coactivation of CTGF. In addition, miR-101-3p suppressed the expression of CTGF by directly targeting the 3'-UTR of IRF2BP2. Taken together, these findings provide a model for the role of miR-101-3p-IRF2BP2-CTGF signalling axis in GC and a novel insight into the mechanism of GC progression and metastasis.

High Risk of Hepatocellular Carcinoma Development in Fibrotic Liver: Role of the Hippo-YAP/TAZ Signaling Pathway

Liver cancer is the fourth leading cause of cancer-related death globally, accounting for approximately 800,000 deaths annually. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, making up about 80% of cases. Liver fibrosis and its end-stage disease, cirrhosis, are major risk factors for HCC. A fibrotic liver typically shows persistent hepatocyte death and compensatory regeneration, chronic inflammation, and an increase in reactive oxygen species, which collaboratively create a tumor-promoting microenvironment via inducing genetic alterations and chromosomal instability, and activating various oncogenic molecular signaling pathways. In this article, we review recent advances in fields of liver fibrosis and carcinogenesis, and consider several molecular signaling pathways that promote hepato-carcinogenesis under the microenvironment of liver fibrosis. In particular, we pay attention to emerging roles of the Hippo-YAP/TAZ signaling pathway in stromal activation, hepatic fibrosis, and liver cancer.

Huaier Augmented the Chemotherapeutic Sensitivity of Oxaliplatin via Downregulation of YAP in Hepatocellular Carcinoma

For unresectable Hepatocellular carcinoma (HCC), chemotherapy is still an important treatment strategy. Oxaliplatin (Oxa) is an effective treatment of HCC after sorafenib treatment failure. However, the intrinsic or acquired resistance of Oxa affected the chemotherapeutic sensitivity. By analyzing the data of GEO Database, we found that Oxa aberrantly increased the expression of Cysteine-rich61 (Cyr61) in HCC cell lines. Subsequently, in Bel-7404 and SMMC-7721 cells after treated with Oxa, it was verified that the expression of Cyr61 and Yes-associated protein (YAP) was increased. Moreover, we found that blockade of YAP promoted Oxa-induced cell apoptosis for the first time. Meanwhile, our previous study demonstrated that Huaier (HE) inhibited the expression of YAP. Further study found that combination treatment of Oxa and HE had a significantly synergistic anti-cancer effect and significantly inhibited the expression of YAP and apoptosis related proteins. Taken together, we have observed that overexpression of YAP significantly reduced the chemotherapeutic sensitivity of Oxa in HCC for the first time. Combination treatment of Oxa and HE solved this problem.

HCV-induced EGFR-ERK signaling promotes a pro-inflammatory and pro-angiogenic signature contributing to liver cancer pathogenesis

HCV is a major risk factor for hepatocellular carcinoma (HCC). HCC development in chronically infected HCV patients has until now been attributed to persistent inflammation and interference of viral proteins with host cell signaling. Since activation of the epidermal growth factor receptor (EGFR) presents a crucial step in HCV entry, we aimed at investigating whether EGFR signaling may contribute to the pathogenesis of HCV-related HCC. By applying microarray analysis, we generated a gene expression signature for secreted proteins in HCV-infected hepatoma cells. This gene signature was enriched for inflammatory and angiogenic processes; both crucially involved in HCC development. RT-qPCR analysis, conducted on the entire list of upregulated genes, confirmed induction of 11 genes (AREG, IL8, CCL20, CSF1, GDF15, IGFBP1, VNN3, THBS1 and PAI-1) in a virus titer- and replication-dependent manner. EGFR activation in hepatoma cells largely mimicked the gene signature seen in the infectious HCV model. Further, the EGFR-ERK pathway, but not Akt signaling, was responsible for this gene expression profile. Finally, microarray analysis conducted on clinical data from the GEO database, revealed that our validated gene expression profile is significantly represented in livers of patients with HCV-related liver pathogenesis (cirrhosis and HCC) compared to healthy livers. Taken together, our data indicate that persistent activation of EGFR-ERK signaling in chronically infected HCV patients may induce a specific pro-inflammatory and pro-angiogenic signature that presents a new mechanism by which HCV can promote liver cancer pathogenesis. A better understanding of the key factors in HCV-related oncogenesis, may efficiently direct HCC drug development.

Three Dimensional Mixed-Cell Spheroids Mimic Stroma-Mediated Chemoresistance and Invasive Migration in hepatocellular carcinoma

Interactions between cancer cells and cancer-associated fibroblasts (CAFs) within the tumor microenvironment (TME) play an important role in promoting the profibrotic microenvironment and epithelial-mesenchymal transition (EMT), resulting in tumor progression and drug resistance in hepatocellular carcinoma (HCC). In the present study, we developed a mixed-cell spheroid model using Huh-7 HCC cells and LX-2 stellate cells to simulate the in vivo tumor environment with respect to tumor-CAF interactions. Spheroids were cultured from cancer cells alone (monospheroids) or as a mixture (mixed-cell spheroids) in ultra-low-attachment plates. Compact, well-mixed, and stroma-rich mixed-cell spheroids were successfully established with heterotypic cell-cell contacts shown by the presence of gap junctions and desmosomes. Mixed-cell spheroids showed enhanced expression of collagen type-I (Col‐I) and pro‐fibrotic factors such as, transforming growth factor beta1 (TGF-β1), and connective tissue growth factor (CTGF) compared to the levels expressed in mono-spheroids. The EMT phenotype was evident in mixed-cell spheroids as shown by the altered expression of E-cadherin and vimentin. Differential drug sensitivity was observed in mixed-cell spheroids, and only sorafenib and oxaliplatin showed dose-dependent antiproliferative effects. Simultaneous treatment with TGF-β inhibitors further improved sorafenib efficacy in the mixed-cell spheroids, indicating the involvement of TGF-β in the mechanism of sorafenib resistance. In 3D matrix invasion assay, mixed-cell spheroids exhibited fibroblast-led collective cell movement. Overall, our results provide evidence that mixed-cell spheroids formed with Huh-7 and LX-2 cells well represent HCC tumors and their TME in vivo and hence are useful in studying tumor-stroma interactions as mechanisms associated with drug resistance and increased cell motility.

CTGF Mediates Tumor-Stroma Interactions between Hepatoma Cells and Hepatic Stellate Cells to Accelerate HCC Progression

Connective tissue growth factor (CTGF) is a matricellular protein related to hepatic fibrosis. This study aims to clarify the roles of CTGF in hepatocellular carcinoma (HCC), which usually develops from fibrotic liver. CTGF was overexpressed in 93 human HCC compared with nontumorous tissues, primarily in tumor cells. Increased CTGF expression was associated with clinicopathologic malignancy of HCC. CTGF was upregulated in hepatoma cells in hepatocyte-specific Kras-mutated mice (Alb-Cre Kras^LSL-G12D/+). Hepatocyte-specific knockout of CTGF in these mice (Alb-Cre Kras^LSL-G12D/+ CTGF^fl/fl) decreased liver tumor number and size. Hepatic stellate cells (HSC) were present in both human and murine liver tumors, and α-SMA expression, a marker of HSC activation, positively correlated with CTGF expression. Forced expression of CTGF did not affect growth of PLC/PRF/5 cells, a hepatoma cell line with little CTGF expression, but facilitated their growth in the presence of LX-2 cells, an HSC line. The growth of HepG2 cells, which express high levels of CTGF, was promoted by coculture with LX-2 cells compared with monoculture. Growth promotion by LX-2 cells was negated by an anti-CTGF antibody in both culture and xenografts. Coculturing LX-2 cells with HepG2 cells drove LX-2-derived production of IL6, which led to STAT-3 activation and proliferation of HepG2 cells. An anti-CTGF antibody reduced IL6 production in LX-2 cells and suppressed STAT-3 activation in HepG2 cells. In conclusion, our data identify tumor cell-derived CTGF as a keystone in the HCC microenvironment, activating nearby HSC that transmit progrowth signals to HCC cells, and this interaction is susceptible to inhibition by an anti-CTGF antibody.Significance: Protumor cross-talk between cancer cells and hepatic stellate cells presents an opportunity for therapeutic intervention against HCC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/17/4902/F1.large.jpg Cancer Res; 78(17); 4902-14. ©2018 AACR.

Lysyl oxidase: A colorectal cancer biomarker of lung and hepatic metastasis

Background

Colorectal cancer (CRC) is a common and lethal disease in which distant metastasis remains the primary cause of death. Paradoxical roles of LOX have been reported in CRC, and the intracellular function of LOX has also recently been determined. Correlations of LOX expression and its intracellular localization with clinicopathological features in CRC patients remain largely unknown. The aim of the present study was to explore the potential roles of LOX in CRC.

Methods

LOX messenger RNA expression was assayed by quantitative PCR in eight paired normal mucosa and tumor tissues. Immunohistochemistry was conducted using tissue arrays to investigate LOX expression in 201 CRC patients. Regulation of LOX by YAP and TEAD4 was explored by YAP or TEAD4 short hairpin RNA interference in a LoVo cell line.

Results

LOX messenger RNA expression was elevated in some CRC specimens, and LOX nuclear localization was detected in CRC tumor tissues. LOX nuclear localization was found to correlate with lung/hepatic metastasis, elevated serum carcinoembryonic antigen concentration, and mucinous tumor type (P < 0.05). Nuclear LOX expression was found to be associated with poor overall and disease‐free survival (P < 0.05), and postoperative lung/hepatic metastasis (P < 0.05). Knockdown of YAP or TEAD4 induced downregulation of LOX expression.

Conclusions

LOX nuclear localization was significantly associated with poor survival in patients with CRC. Nuclear LOX expression was correlated with synchronous or postoperative lung/hepatic metastasis. LOX may prove to be a potential target gene of YAP and TEAD4.

A Randomized Phase II Open-Label Multi-Institution Study of the Combination of Bevacizumab and Erlotinib Compared to Sorafenib in the First-Line Treatment of Patients with Advanced Hepatocellular Carcinoma

OBJECTIVES

To investigate the clinical efficacy and tolerability of the combination of bevacizumab (B) and erlotinib (E) compared to sorafenib (S) as first-line treatment for patients with advanced hepatocellular carcinoma (HCC).

METHODS

A total of 90 patients with advanced HCC, Child-Pugh class A-B7 cirrhosis, and no prior systemic therapy were randomly assigned (1: 1) to receive either 10 mg/kg B intravenously every 14 days and 150 mg E orally daily (n = 47) (B+E) or 400 mg S orally twice daily (n = 43). The primary endpoint was overall survival (OS). Secondary endpoints included event-free survival (EFS), objective response rate based on Response Evaluation Criteria in Solid Tumors (RECIST 1.1), time to progression, and safety and tolerability.

RESULTS

The median OS was 8.55 months (95% CI: 7.00-13.9) for patients treated with B+E and 8.55 months (95% CI: 5.69-12.2) for patients receiving S. The hazard ratio (HR) for OS was 0.92 (95% CI: 0.57-1.47). The median EFS was 4.37 months (95% CI: 2.99-7.36) for patients receiving B+E and 2.76 months (95% CI: 1.84-4.80) for patients receiving S. The HR for EFS was 0.67 (95% CI: 0.42-1.07; p = 0.09), favoring B+E over S. When OS was assessed among patients who were Child-Pugh class A, the median OS was 11.4 months (95% CI: 7.5-15.7) for patients treated with B+E (n = 39) and 10.26 months (95% CI: 5.9-13.0) for patients treated with S (n = 38) (HR = 0.88; 95% CI: 0.53-1.46).

CONCLUSIONS

There was no difference in efficacy between the B+E and S arms, although the safety and tolerability profile tended to favor B+E over S based on competing risk analysis.

The role of Hippo signal pathway in breast cancer metastasis

The Hippo pathway is a novel and highly conserved mammalian signaling pathway. Mutations and altered expression of core Hippo pathway components promote the migration, invasion, malignancy, and chemotherapy resistance of breast cancer cells. In cancer metastasis, tumor cells must detach from the primary tumor, invade surrounding tissue, and enter and survive in a foreign microenvironment. The metastatic potential of breast cancer is closely related to individual patient genetic profile. Nevertheless, the exact molecular mechanism that regulates the Hippo pathway in breast cancer metastasis is yet to be fully elucidated. This article discusses the function and regulation of the Hippo pathway, with focus given to its role in the context of breast cancer metastasis.

YAP/TAZ Activation as a Target for Treating Metastatic Cancer

Yes-Associated Protein (YAP) and Transcriptional Co-activator with PDZ-binding Motif (TAZ) have both emerged as important drivers of cancer progression and metastasis. YAP and TAZ are often upregulated or nuclear localized in aggressive human cancers. There is abundant experimental evidence demonstrating that YAP or TAZ activation promotes cancer formation, tumor progression, and metastasis. In this review we summarize the evidence linking YAP/TAZ activation to metastasis, and discuss the roles of YAP and TAZ during each step of the metastatic cascade. Collectively, this evidence strongly suggests that inappropriate YAP or TAZ activity plays a causal role in cancer, and that targeting aberrant YAP/TAZ activation is a promising strategy for the treatment of metastatic disease. To this end, we also discuss several potential strategies for inhibiting YAP/TAZ activation in cancer and the challenges each strategy poses.

Proliferation of hepatic stellate cells, mediated by YAP and TAZ, contributes to liver repair and regeneration after liver ischemia-reperfusion injury

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are key regulators of cell proliferation and organ size; however, their physiological contribution after liver injury has not been fully understood. In this study, we sought to determine the role of YAP and TAZ during liver recovery after ischemia-reperfusion (I/R). A murine model of partial (70%) I/R was used to induce liver injury and study the reparative and regenerative response. After liver injury, there was marked activation and proliferation of hepatic stellate cells. The Hippo pathway components, large tumor suppressor 1 (LATS1) and its adapter protein, Mps one binder 1 (MOB1), were inactivated during liver repair, and YAP and TAZ were activated selectively in hepatic stellate cells. Concurrently, the expression of connective tissue growth factor and survivin, both of which are YAP and TAZ target genes, were upregulated. Hepatic stellate cell expansion and concomitant activation of YAP and TAZ occurred only in the injured liver and were not observed in the nonischemic liver. Treatment of mice with verteporfin, an inhibitor of YAP and TAZ, decreased hepatic stellate cell proliferation, survivin, and cardiac ankyrin repeat protein expression. These changes were associated with a significant decrease in hepatocyte proliferation. The data suggest that liver repair and regeneration after I/R injury are dependent on hepatic stellate cell proliferation, which is mediated by YAP and TAZ. NEW & NOTEWORTHY This study is the first to assess the proliferation of hepatic stellate cells (HSCs) after ischemia-reperfusion (I/R) injury and their role in the reparative and regenerative process. Here we show that the Hippo pathway is inactivated after I/R and that Yes-associated protein/transcriptional coactivator with PDZ-binding motif (YAP/TAZ) activation is detected in HSC. HSC proliferation and expansion are prominent during liver recovery after I/R injury. Inhibition of YAP/TAZ activation with verteporfin reduces HSC proliferation and target gene expression and attenuates hepatocyte proliferation.

Resistance a major hindrance to chemotherapy in hepatocellular carcinoma: an insight

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer mortality, accounting for almost 90% of total liver cancer burden. Surgical resection followed by adjuvant and systemic chemotherapy are the most meticulously followed treatment procedures but the complex etiology and high metastatic potential of the disease renders surgical treatment futile in majority of the cases. Another hindrance to the scenario is the acquired resistance to drugs resulting in relapse of the disease. Hence, to provide insights into development of novel therapeutic targets and diagnostic biomarkers, this review focuses on the various molecular mechanisms underlying chemoresistance in HCC. We have provided a comprehensive summary of the various strategies adopted by HCC cells, extending from apoptosis evasion, autophagy activation, drug expulsion to epigenetic transformation as modes of therapy resistance. The role of stem cells in imparting chemoresistance is also discussed. Furthermore, the review also focuses on how this knowledge might be exploited for the development of an effective, prospective therapy against HCC.

EGFR-PI3K-PDK1 pathway regulates YAP signaling in hepatocellular carcinoma: the mechanism and its implications in targeted therapy

The epidermal growth factor receptor (EGFR) pathway and Hippo signaling play an important role in the carcinogenesis of hepatocellular carcinoma (HCC). However, the crosstalk between these two pathways and its implications in targeted therapy remains unclear. We found that the activated EGFR signaling could bypass RhoA to promote the expression of YAP(Yes-associated protein), the core effector of the Hippo signaling, and its downstream target Cyr61. Further studies indicated that EGFR signaling mainly acted through the PI3K-PDK1 (Phosphoinositide 3-kinase-Phosphoinositide-dependent kinase-1) pathway to activate YAP, but not the AKT and MAPK pathways. While YAP knockdown hardly affected the EGFR signaling. In addition, EGF could promote the proliferation of HCC cells in a YAP-independent manner. Combined targeting of YAP and EGFR signaling by simvastatin and the EGFR signaling inhibitors, including the EGFR tyrosine kinase inhibitor (TKI) gefitinib, the RAF inhibitor sorafenib and the MEK inhibitor trametinib, presented strong synergistic cytotoxicities in HCC cells. Therefore, the EGFR-PI3K-PDK1 pathway could activate the YAP signaling, and the activated EGFR signaling could promote the HCC cell growth in a YAP-independent manner. Combined use of FDA-approved inhibitors to simultaneously target YAP and EGFR signaling presented several promising therapeutic approaches for HCC treatment.

Novel candidate genes important for asthma and hypertension comorbidity revealed from associative gene networks

BACKGROUND

Hypertension and bronchial asthma are a major issue for people's health. As of 2014, approximately one billion adults, or ~ 22% of the world population, have had hypertension. As of 2011, 235-330 million people globally have been affected by asthma and approximately 250,000-345,000 people have died each year from the disease. The development of the effective treatment therapies against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and their treatment. Hence, in this study the bioinformatical methodology for the analysis of the comorbidity of these two diseases have been developed. As such, the search for candidate genes related to the comorbid conditions of asthma and hypertension can help in elucidating the molecular mechanisms underlying the comorbid condition of these two diseases, and can also be useful for genotyping and identifying new drug targets.

RESULTS

Using ANDSystem, the reconstruction and analysis of gene networks associated with asthma and hypertension was carried out. The gene network of asthma included 755 genes/proteins and 62,603 interactions, while the gene network of hypertension - 713 genes/proteins and 45,479 interactions. Two hundred and five genes/proteins and 9638 interactions were shared between asthma and hypertension. An approach for ranking genes implicated in the comorbid condition of two diseases was proposed. The approach is based on nine criteria for ranking genes by their importance, including standard methods of gene prioritization (Endeavor, ToppGene) as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analysed genes. According to the proposed approach, the genes IL10, TLR4, and CAT had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the list of top genes is enriched with apoptotic genes and genes involved in biological processes related to the functioning of central nervous system.

CONCLUSIONS

The application of methods of reconstruction and analysis of gene networks is a productive tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance to the comorbid condition of asthma and hypertension was employed that resulted in prediction of 10 genes, playing the key role in the development of the comorbid condition. The results can be utilised to plan experiments for identification of novel candidate genes along with searching for novel pharmacological targets.

miR-375 is involved in Hippo pathway by targeting YAP1/TEAD4-CTGF axis in gastric carcinogenesis

miR-375 is a tumor-suppressive microRNA (miRNA) in gastric cancer (GC). However, its molecular mechanism remains unclear. The aim of this study is to comprehensively investigate how miR-375 is involved in Hippo pathway by targeting multiple oncogenes. miR-375 expression in gastric cancer cell lines and primary GC was investigated by qRT-PCR. The regulation of YAP1, TEAD4, and CTGF expression by miR-375 was evaluated by qRT-PCR, western blot, and luciferase reporter assays, respectively. The functional roles of the related genes were examined by siRNA-mediated knockdown or ectopic expression assays. The clinical significance and expression correlation analysis of miR-375, YAP1, and CTGF were performed in primary GCs. TCGA cohort was also used to analyze the expression correlation of YAP1, TEAD4, CTGF, and miR-375 in primary GCs. miR-375 was down-regulated in GC due to promoter methylation and histone deacetylation. miR-375 downregulation was associated with unfavorable outcome and lymph node metastasis. Ectopic expression of miR-375 inhibited tumor growth in vitro and in vivo. Three components of Hippo pathway, YAP1, TEAD4 and CTGF, were revealed to be direct targets of miR-375. The expression of three genes showed a negative correlation with miR-375 expression and YAP1 re-expression partly abolished the tumor-suppressive effect of miR-375. Furthermore, CTGF was confirmed to be the key downstream of Hippo-YAP1 cascade and its knockdown phenocopied siYAP1 or miR-375 overexpression. YAP1 nuclear accumulation was positively correlated with CTGF cytoplasmic expression in primary GC tissues. Verteporfin exerted an anti-oncogenic effect in GC cell lines by quenching CTGF expression through YAP1 degradation. In short, miR-375 was involved in the Hippo pathway by targeting YAP1-TEAD4-CTGF axis and enriched our knowledge on the miRNA dysregulation in gastric tumorigenesis.

Functional genomics screen identifies YAP1 as a key determinant to enhance treatment sensitivity in lung cancer cells

Survival for lung cancer patients remains dismal and is largely attributed to treatment resistance. To identify novel target genes the modulation of which could modify platinum resistance, we performed a high-throughput RNAi screen and identified Yes-associated protein (YAP1), a transcription coactivator and a known oncogene, as a potential actionable candidate. YAP1 ablation significantly improved sensitivities not only to cisplatin but also to ionizing radiation, both of which are DNA-damaging interventions, in non-small cell lung cancer (NSCLC) cells. Overall YAP1 was expressed in 75% of NSCLC specimens, whereas nuclear YAP1 which is the active form was present in 45% of 124 resected NSCLC. Interestingly, EGFR-mutated or KRAS-mutated NSCLC were associated with higher nuclear YAP1 staining in comparison to EGFR/KRAS wild-type. Relevantly, YAP1 downregulation improved sensitivity to erlotinib, an EGFR inhibitor. A pharmacological inhibitor of YAP1 signaling, verteporfin also synergized with cisplatin, radiation and erlotinib in NSCLC cells by potentiating cisplatin and radiation-related double-stranded breaks and decreasing expression of YAP1 and EGFR. Taken together, our study is the first to indicate the potential role of YAP1 as a common modulator of resistance mechanisms and a potential novel, actionable target that can improve responses to platinum, radiation and EGFR-targeted therapy in lung cancer.

The GSK3β inhibitor BIS I reverts YAP-dependent EMT signature in PDAC cell lines by decreasing SMADs expression level

The Yes-associated protein, YAP, is a transcriptional co-activator, mediating the Epithelial to Mesenchymal Transition program in pancreatic ductal adenocarcinoma (PDAC). With the aim to identify compounds that can specifically modulate YAP functionality in PDAC cell lines, we performed a small scale, drug-based screening experiment using YAP cell localization as the read-out. We identified erlotinib as an inducer of YAP cytoplasmic localization, an inhibitor of the TEA luciferase reporter system and the expression of the bona fide YAP target gene, Connective Tissue Growth Factor CTGF. On the other hand, BIS I, an inhibitor of PKCδ and GSK3β, caused YAP accumulation into the nucleus. Activation of β-catenin reporter and interfering experiments show that inhibition of the PKCδ/GSK3β pathway triggers YAP nuclear accumulation inducing YAP/TEAD transcriptional response. Inhibition of GSK3β by BIS I reduced the expression levels of SMADs protein and reduced YAP contribution to EMT. Notably, BIS I reduced proliferation, migration and clonogenicity of PDAC cells in vitro, phenocopying YAP genetic down-regulation. As shown by chromatin immunoprecipitation experiments and YAP over-expressing rescue experiments, BIS I reverted YAP-dependent EMT program by modulating the expression of the YAP target genes E-cadherin, vimentin, CTGF and of the newly identified target, CD133. In conclusion, we identified two different molecules, erlotinib and BIS I, modulating YAP functionality although via different mechanisms of action, with the second one specifically inhibiting the YAP-dependent EMT program in PDAC cell lines.

Overexpression of Yes-associated protein and its association with clinicopathological features of hepatocellular carcinoma: A meta-analysis

BACKGROUND

Yes-associated protein (YAP) overexpression is reported to be associated with risk of hepatocellular carcinoma (HCC) but current studies have not explored the relationship between YAP expression with HCC clinicopathological features.

METHODS

To assess these associations, a meta-analysis was performed which included four eligible studies including 391 HCC cases and 334 controls. There were eight eligible studies to investigate the association between YAP expression in HCC and clinicopathological features of liver cancer patients. Literature was obtained from PubMed, Embase, Wangfang and China National Knowledge Infrastructure.

RESULTS

Analysis indicated that YAP expression in HCC was greater than in adjacent non-tumour tissue (odds ratio [OR], 15.80, 95% confidence interval [CI], 10.53-23.70, P<.00001; heterogeneity=.30). YAP overexpression in HCC was significantly associated with vascular invasion (OR, 2.21, 95% CI, 11.64-2.97, P<.00001, heterogeneity=.10), less cellular differentiation (OR, 2.38, 95% CI, 1.61-3.51, P<.00001, heterogeneity=.333), tumours larger than 5 cm (OR, 2.52, 95% CI, 1.75-3.62, P<.00001; heterogeneity=.17) and TNM tumour stage I + II (OR, 0.44, 95% CI, 0.28-0.75, P=.00003, heterogeneity=.12).

CONCLUSIONS

Overexpression of YAP contributes to HCC formation, and its overexpression is associated with vascular invasion, low cellular differentiation tumours larger than 5 cm and TNM tumour stage III + IV.

Smurf2, an E3 ubiquitin ligase, interacts with PDE4B and attenuates liver fibrosis through miR-132 mediated CTGF inhibition

We previously reported that Smad ubiquitin regulatory factor 2 (Smurf2) activity was decreased in human fibrotic livers. Here, we overexpressed Smurf2 in livers of transgenic mice and observed inhibited collagen deposition and hepatic stellate cell activation in fibrotic model induced by carbon tetrachloride treatment or bile duct ligation. Hepatic Smurf2 overexpression also inhibited the production of connective tissue growth factor (CTGF), a central mediator of liver fibrosis. Using miRNA array and bioinformatics analyses, we identified miR-132 as a mediator of this inhibitory effect. miR-132 directly targets the 3'-untranslated region of CTGF and was transcriptionally upregulated by cAMP-PKA-CREB signaling. In addition, Smurf2 activated cAMP-PKA-CREB pathway by interacting with phosphodiesterase 4B (PDE4B) and facilitating its degradation. Thus, we have demonstrated a previously unrecognized anti-fibrotic pathway controlled by Smurf2.

TGF-β-independent CTGF induction regulates cell adhesion mediated drug resistance by increasing collagen I in HCC

Hepatocellular carcinoma (HCC) is resistant to conventional chemotherapeutic agents and remains an unmet medical need. Here, we demonstrate a mechanism of cell adhesion-mediated drug resistance using a variety of HCC spheroid models to overcome environment-mediated drug resistance in HCC. We classified spheroids into two groups, tightly compacted and loosely compacted aggregates, based on investigation of dynamics of spheroid formation. Our results show that compactness of HCC spheroids correlated with fibroblast-like characteristics, collagen 1A1 (COL1A1) content, and capacity for chemoresistance. We also showed that ablation of COL1A1 attenuated not only the capacity for compact-spheroid formation, but also chemoresistance. Generally, connective tissue growth factor (CTGF) acts downstream of transforming growth factor (TGF)-β and promotes collagen I fiber deposition in the tumor microenvironment. Importantly, we found that TGF-β-independent CTGF is upregulated and regulates cell adhesion-mediated drug resistance by inducing COL1A1 in tightly compacted HCC spheroids. Furthermore, losartan, which inhibits collagen I synthesis, impaired the compactness of spheroids via disruption of cell-cell contacts and increased the efficacy of anticancer therapeutics in HCC cell line- and HCC patient-derived tumor spheroids. These results strongly suggest functional roles for CTGF-induced collagen I expression in formation of compact spheroids and in evading anticancer therapies in HCC, and suggest that losartan, administered in combination with conventional chemotherapy, might be an effective treatment for liver cancer.

Low angiomotin-p130 with concomitant high Yes-associated protein 1 expression is associated with adverse prognosis of advanced gastric cancer

Angiomotin (AMOT) promotes angiogenesis and plays a role in neovascularization during tumorigenesis. Recently, the AMOT isoform, AMOT-p130, was shown to exert a regulatory effect on Yes-associated protein 1 (YAP1), a major downstream effector of the Hippo pathway. The specific roles of AMOT-p130 and YAP1 in advanced gastric cancer (AGC) are yet to be established. In this study, a total of 166 patients with AGC were enrolled, and AMOT-p130 and YAP1 levels were analyzed by immunohistochemistry using tissue microarrays. Low AMOT-p130 together with high YAP1 expression (n = 30, 18.1%) was associated with high T stage (p = 0.042), high TNM stage (p = 0.025), and venous invasion (p = 0.048). A Kaplan-Meier survival analysis with log-rank test revealed a significant correlation with decreased AMOT-p130 coupled with high nuclear YAP1 expression with shorter overall survival (p = 0.0045) and disease-free survival (p = 0.0028). Furthermore, multivariate analyses showed that the low AMOT-p130/high YAP1 expression profile was an independent prognostic factor for disease-free survival (p = 0.008, HR = 1.874, CI, 1.177-2.986) and overall survival (p = 0.012, HR = 1.903, CI, 1.152-3.143). Our findings collectively demonstrate that low AMOT-p130 combined with high YAP1 expression is correlated with an unfavorable AGC prognosis.

Dual roles of yes-associated protein (YAP) in colorectal cancer

Yes-associated protein (YAP) is a downstream effector molecule of a newly emerging tumour suppressor pathway called the Hippo pathway. YAP is a transcriptional co-activator and mis-expressed in various cancers, including colorectal cancer (CRC). Accumulating studies show that the high expression of nuclear YAP is linked with tumour progression and decreased survival. Nuclear YAP can interact with other transcription factors to promote cancer cell proliferation, apoptosis, metastasis and maintenance of stemness. Therefore, YAP has the potential to be a tumour biomarker or therapeutic target for CRC. However, recently, a number of studies have supported a contradictory role for YAP as a tumour suppressor, demonstrating inhibition of the tumorigenesis of CRC, involvement in promoting cell apoptosis, and inhibiting the maintenance of intestinal stem cells and inflammatory activity. In these studies, high expression of YAP was highly correlated with worse survival in CRC. In this review, we will comprehensively summarize and analyse these paradoxical reports, and discuss both the oncogenic and tumour suppressor functions of YAP in the differential status of CRC progression. Further investigation into the mechanisms responsible for the dual function of YAP will be of great value in the prevention, early diagnosis, and therapy of CRC.

Bile acids, FGF15/19 and liver regeneration: From mechanisms to clinical applications

The liver has an extraordinary regenerative capacity rapidly triggered upon injury or resection. This response is intrinsically adjusted in its initiation and termination, a property termed the "hepatostat". Several molecules have been involved in liver regeneration, and among them bile acids may play a central role. Intrahepatic levels of bile acids rapidly increase after resection. Through the activation of farnesoid X receptor (FXR), bile acids regulate their hepatic metabolism and also promote hepatocellular proliferation. FXR is also expressed in enterocytes, where bile acids stimulate the expression of fibroblast growth factor 15/19 (FGF15/19), which is released to the portal blood. Through the activation of FGFR4 on hepatocytes FGF15/19 regulates bile acids synthesis and finely tunes liver regeneration as part of the "hepatostat". Here we review the experimental evidences supporting the relevance of the FXR-FGF15/19-FGFR4 axis in liver regeneration and discuss potential therapeutic applications of FGF15/19 in the prevention of liver failure. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Hepatocyte ERBB3 and EGFR are required for maximal CCl4-induced liver fibrosis

Epidermal growth factor receptor (EGFR) and its ligands have been implicated in liver fibrosis. However, it has not been directly shown that hepatocellular genetic ablation of either this receptor tyrosine kinase or ERBB3, its interactive signaling partner, affects hepatic fibrosis. Carbon tetrachloride (CCl₄)-induced liver fibrosis in hepatocyte-specific (HS) mouse models of EGFR and ERBB3 ablation was evaluated in both single gene knockouts and an HS-EGFR-ERBB3 double knockout (DKO). Loss of hepatocellular EGFR or ERBB3 did not impact cytochrome P450-2E1 expression, the extent of centrilobular injury, or the initial regenerative response, but it did diminish liver fibrosis induced by chronic intraperitoneal administration of CCl₄ The reduction of liver fibrosis correlated with reduced α-smooth muscle actin expression. Maximal impact to fibrogenesis occurred in the ERBB3 and EGFR-ERBB3 DKO models, suggesting that EGFR-ERBB3 heterodimeric signaling in damaged hepatocytes may play a more important role in liver fibrosis than EGFR-EGFR homodimeric signaling. Immunohistochemical analyses of phospho-EGFR and phospho-ERBB3 isoforms revealed clear staining in hepatocytes, activated stellate cells, and macrophages. Our results support a role for the hepatocellular ERBB tyrosine kinases in fibrogenesis and suggest that pharmacologic inhibition of EGFR-ERBB3 signaling may reverse or retard hepatic fibrosis.

Post-translational deregulation of YAP1 is genetically controlled in rat liver cancer and determines the fate and stem-like behavior of the human disease

Previous studies showed that YAP1 is over-expressed in hepatocellular carcinoma (HCC). Here we observed higher expression of Yap1/Ctgf axis in dysplastic nodules and HCC chemically-induced in F344 rats, genetically susceptible to hepatocarcinogenesis, than in lesions induced in resistant BN rats. In BN rats, highest increase in Yap1-tyr357, p73 phosphorylation and Caspase 3 cleavage occurred. In human HCCs with poorer prognosis (< 3 years survival after partial liver resection, HCCP), levels of YAP1, CTGF, 14-3-3, and TEAD proteins, and YAP1-14-3-3 and YAP1-TEAD complexes were higher than in HCCs with better outcome (> 3 years survival; HCCB). In the latter, higher levels of phosphorylated YAP1-ser127, YAP1-tyr357 and p73, YAP1 ubiquitination, and Caspase 3 cleavage occurred. Expression of stemness markers NANOG, OCT-3/4, and CD133 were highest in HCCP and correlated with YAP1 and YAP1-TEAD levels. In HepG2, Huh7, and Hep3B cells, forced YAP1 over-expression led to stem cell markers expression and increased cell viability, whereas inhibition of YAP1 expression by specific siRNA, or transfection of mutant YAP1 which does not bind to TEAD, induced opposite alterations. These changes were associated, in Huh7 cells transfected with YAP1 or YAP1 siRNA, with stimulation or inhibition of cell migration and invasivity, respectively. Furthermore, transcriptome analysis showed that YAP1 transfection in Huh7 cells induces over-expression of genes involved in tumor stemness. In conclusion, Yap1 post-translational modifications favoring its ubiquitination and apoptosis characterize HCC with better prognosis, whereas conditions favoring the formation of YAP1-TEAD complexes are associated with aggressiveness and acquisition of stemness features by HCC cells.

Inactivation of hypoxia-induced YAP by statins overcomes hypoxic resistance tosorafenib in hepatocellular carcinoma cells

Sorafenib is a multikinase inhibitor used as a first-line treatment for advanced hepatocellular carcinoma (HCC), but it has shown modest to low response rates. The characteristic tumour hypoxia of advanced HCC maybe a major factor underlying hypoxia-mediated treatment failure. Thus, it is urgent to elucidate the mechanisms of hypoxia-mediated sorafenib resistance in HCC. In this study, we found that hypoxia induced the nuclear translocation of Yes associate-Protein (YAP) and the subsequent transactivation of target genes that promote cell survival and escape apoptosis, thereby leading to sorafenib resistance. Statins, the inhibitors of hydroxymethylglutaryl-CoA reductase, could ameliorate hypoxia-induced nuclear translocation of YAP and suppress mRNA levels of YAP target genes both in vivo and in vitro. Combined treatment of statins with sorafenib greatly rescued the loss of anti-proliferative effects of sorafenib under hypoxia and improved the inhibitory effects on HepG2 xenograft tumour growth, accompanied by enhanced apoptosis as evidenced by the increased sub-G1 population and PARP cleavage. The expression levels of YAP and its target genes were highly correlated with poor prognosis and predicted a high risk of HCC patients. These findings collectively suggest that statins utilization maybe a promising new strategy to counteract hypoxia-mediated resistance to sorafenib in HCC patients.