Hippo Pathway in Cancer: Aberrant Regulation and Therapeutic Opportunities

Exploring the impact of circRNAs on cancer glycolysis: Insights into tumor progression and therapeutic strategies

Cancer cells exhibit altered metabolic pathways, prominently featuring enhanced glycolytic activity to sustain their rapid growth and proliferation. Dysregulation of glycolysis is a well-established hallmark of cancer and contributes to tumor progression and resistance to therapy. Increased glycolysis supplies the energy necessary for increased proliferation and creates an acidic milieu, which in turn encourages tumor cells' infiltration, metastasis, and chemoresistance. Circular RNAs (circRNAs) have emerged as pivotal players in diverse biological processes, including cancer development and metabolic reprogramming. The interplay between circRNAs and glycolysis is explored, illuminating how circRNAs regulate key glycolysis-associated genes and enzymes, thereby influencing tumor metabolic profiles. In this overview, we highlight the mechanisms by which circRNAs regulate glycolytic enzymes and modulate glycolysis. In addition, we discuss the clinical implications of dysregulated circRNAs in cancer glycolysis, including their potential use as diagnostic and prognostic biomarkers. All in all, in this overview, we provide the most recent findings on how circRNAs operate at the molecular level to control glycolysis in various types of cancer, including hepatocellular carcinoma (HCC), prostate cancer (PCa), colorectal cancer (CRC), cervical cancer (CC), glioma, non-small cell lung cancer (NSCLC), breast cancer, and gastric cancer (GC). In conclusion, this review provides a comprehensive overview of the significance of circRNAs in cancer glycolysis, shedding light on their intricate roles in tumor development and presenting innovative therapeutic avenues.

Identification of resistance mechanisms to small-molecule inhibition of TEAD-regulated transcription

The Hippo tumor suppressor pathway controls transcription by regulating nuclear abundance of YAP and TAZ, which activate transcription with the TEAD1-TEAD4 DNA-binding proteins. Recently, several small-molecule inhibitors of YAP and TEADs have been reported, with some entering clinical trials for different cancers with Hippo pathway deregulation, most notably, mesothelioma. Using genome-wide CRISPR/Cas9 screens we reveal that mutations in genes from the Hippo, MAPK, and JAK-STAT signaling pathways all modulate the response of mesothelioma cell lines to TEAD palmitoylation inhibitors. By exploring gene expression programs of mutant cells, we find that MAPK pathway hyperactivation confers resistance to TEAD inhibition by reinstating expression of a subset of YAP/TAZ target genes. Consistent with this, combined inhibition of TEAD and the MAPK kinase MEK, synergistically blocks proliferation of multiple mesothelioma and lung cancer cell lines and more potently reduces the growth of patient-derived lung cancer xenografts in vivo. Collectively, we reveal mechanisms by which cells can overcome small-molecule inhibition of TEAD palmitoylation and potential strategies to enhance the anti-tumor activity of emerging Hippo pathway targeted therapies.

YAP/TAZ enhances P-body formation to promote tumorigenesis

The role of processing bodies (P-bodies) in tumorigenesis and tumor progression is not well understood. Here, we showed that the oncogenes YAP/TAZ promote P-body formation in a series of cancer cell lines. Mechanistically, both transcriptional activation of the P-body-related genes SAMD4A, AJUBA, and WTIP and transcriptional suppression of the tumor suppressor gene PNRC1 are involved in enhancing the effects of YAP/TAZ on P-body formation in colorectal cancer (CRC) cells. By reexpression of PNRC1 or knockdown of P-body core genes (DDX6, DCP1A, and LSM14A), we determined that disruption of P-bodies attenuates cell proliferation, cell migration, and tumor growth induced by overexpression of YAP5SA in CRC. Analysis of a pancancer CRISPR screen database (DepMap) revealed co-dependencies between YAP/TEAD and the P-body core genes and correlations between the mRNA levels of SAMD4A, AJUBA, WTIP, PNRC1, and YAP target genes. Our study suggests that the P-body is a new downstream effector of YAP/TAZ, which implies that reexpression of PNRC1 or disruption of P-bodies is a potential therapeutic strategy for tumors with active YAP.

Discovery of YAP1/TAZ pathway inhibitors through phenotypic screening with potent anti-tumor activity via blockade of Rho-GTPase signaling

This study describes the identification and target deconvolution of small molecule inhibitors of oncogenic Yes-associated protein (YAP1)/TAZ activity with potent anti-tumor activity in vivo. A high-throughput screen (HTS) of 3.8 million compounds was conducted using a cellular YAP1/TAZ reporter assay. Target deconvolution studies identified the geranylgeranyltransferase-I (GGTase-I) complex as the direct target of YAP1/TAZ pathway inhibitors. The small molecule inhibitors block the activation of Rho-GTPases, leading to subsequent inactivation of YAP1/TAZ and inhibition of cancer cell proliferation in vitro. Multi-parameter optimization resulted in BAY-593, an in vivo probe with favorable PK properties, which demonstrated anti-tumor activity and blockade of YAP1/TAZ signaling in vivo.

YAP-LAMB3 axis dictates cellular resistance of pancreatic ductal adenocarcinoma cells to gemcitabine

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with poor prognosis and inadequate response to treatment, such as gemcitabine (Gem), the first-line chemotherapeutic drug. Understanding the molecular determinants that control drug resistance to Gem is critical to predict potentially responsive patients and improve the benefits of Gem therapy. Emerging evidence suggests that certain developmental pathways, such as Hippo signaling, are aberrated and play important roles in Gem resistance in cancers. Although Hippo signaling has been reported to play a role in chemoresistance in cancers, it has not been clarified which specific target gene(s) functionally mediates the effect. In the present study, we found that YAP serves as a potent barrier for the cellular sensitivity of PDAC cells to Gem. We then identified and characterized laminin subunit beta 3 (LAMB3) as a bona fide target of YAP-TEAD4 to amplify YAP signaling via a feedback loop. Such a YAP-LAMB3 axis is critical to induce epithelial-mesenchymal transition and mediate Gem resistance. Taken together, we uncovered that YAP-LAMB3 axis is an important regulator of Gem, thus providing potential therapeutic targets for overcoming Gem resistance in PDAC.

Multiple aspects of matrix stiffness in cancer progression

The biophysical and biomechanical properties of the extracellular matrix (ECM) are crucial in the processes of cell differentiation and proliferation. However, it is unclear to what extent tumor cells are influenced by biomechanical and biophysical changes of the surrounding microenvironment and how this response varies between different tumor forms, and over the course of tumor progression. The entire ensemble of genes encoding the ECM associated proteins is called matrisome. In cancer, the ECM evolves to become highly dysregulated, rigid, and fibrotic, serving both pro-tumorigenic and anti-tumorigenic roles. Tumor desmoplasia is characterized by a dramatic increase of α-smooth muscle actin expressing fibroblast and the deposition of hard ECM containing collagen, fibronectin, proteoglycans, and hyaluronic acid and is common in many solid tumors. In this review, we described the role of inflammation and inflammatory cytokines, in desmoplastic matrix remodeling, tumor state transition driven by microenvironment forces and the signaling pathways in mechanotransduction as potential targeted therapies, focusing on the impact of qualitative and quantitative variations of the ECM on the regulation of tumor development, hypothesizing the presence of matrisome drivers, acting alongside the cell-intrinsic oncogenic drivers, in some stages of neoplastic progression and in some tumor contexts, such as pancreatic carcinoma, breast cancer, lung cancer and mesothelioma.

Targeting the Hippo pathway to prevent radioresistance brain metastases from the lung (Review)

The prognosis for patients with non‑small cell lung cancer (NSCLC), a cancer type which represents 85% of all lung cancers, is poor with a 5‑year survival rate of 19%, mainly because NSCLC is diagnosed at an advanced and metastatic stage. Despite recent therapeutic advancements, ~50% of patients with NSCLC will develop brain metastases (BMs). Either surgical BM treatment alone for symptomatic patients and patients with single cerebral metastases, or in combination with stereotactic radiotherapy (RT) for patients who are not suitable for surgery or presenting with fewer than four cerebral lesions with a diameter range of 5‑30 mm, or whole‑brain RT for numerous or large BMs can be administered. However, radioresistance (RR) invariably prevents the action of RT. Several mechanisms of RR have been described including hypoxia, cellular stress, presence of cancer stem cells, dysregulation of apoptosis and/or autophagy, dysregulation of the cell cycle, changes in cellular metabolism, epithelial‑to‑mesenchymal transition, overexpression of programmed cell death‑ligand 1 and activation several signaling pathways; however, the role of the Hippo signaling pathway in RR is unclear. Dysregulation of the Hippo pathway in NSCLC confers metastatic properties, and inhibitors targeting this pathway are currently in development. It is therefore essential to evaluate the effect of inhibiting the Hippo pathway, particularly the effector yes‑associated protein‑1, on cerebral metastases originating from lung cancer.

NEDD8 enhances Hippo signaling by mediating YAP1 neddylation

The Hippo-YAP signaling pathway plays a central role in many biological processes such as regulating cell fate, organ size, and tissue growth, and its key components are spatiotemporally expressed and posttranslationally modified during these processes. Neddylation is a posttranslational modification that involves the covalent attachment of NEDD8 to target proteins by NEDD8-specific E1-E2-E3 enzymes. Whether neddylation is involved in Hippo-YAP signaling remains poorly understood. Here, we provide evidence supporting the critical role of NEDD8 in facilitating the Hippo-YAP signaling pathway by mediating neddylation of the transcriptional coactivator yes-associated protein 1 (YAP1). Overexpression of NEDD8 induces YAP1 neddylation and enhances YAP1 transactivity, but inhibition of neddylation suppresses YAP1 transactivity and attenuates YAP1 nuclear accumulation. Furthermore, inhibition of YAP1 signaling promotes MLN4924-induced ovarian granulosa cells apoptosis and disruption of nedd8 in zebrafish results in downregulation of yap1-activated genes and upregulation of yap1-repressed genes. Further assays show that the xiap ligase promotes nedd8 conjugates to yap1 and that yap1 neddylation. In addition, we identify lysine 159 as a major neddylation site on YAP1. These findings reveal a novel mechanism for neddylation in the regulation of Hippo-YAP signaling.

Crosstalk between CAFs and tumour cells in head and neck cancer

Head and neck squamous cell carcinomas (HNSCCs) are amongst the most aggressive, complex, and heterogeneous malignancies. The standard of care treatments for HNC patients include surgery, radiotherapy, chemotherapy, or their combination. However, around 50% do not benefit while suffering severe toxic side effects, costing the individuals and society. Decades have been spent to improve HNSCC treatment outcomes with only limited success. Much of the research in HNSCC treatment has focused on understanding the genetics of the HNSCC malignant cells, but it has become clear that tumour microenvironment (TME) plays an important role in the progression as well as treatment response in HNSCC. Understanding the crosstalk between cancer cells and TME is crucial for inhibiting progression and treatment resistance. Cancer-associated fibroblasts (CAFs), the predominant component of stroma in HNSCC, serve as the primary source of extra-cellular matrix (ECM) and various pro-tumoral composites in TME. The activation of CAFs in HNSCC is primarily driven by cancer cell-secreted molecules, which in turn induce phenotypic changes, elevated secretive status, and altered ECM production profile. Concurrently, CAFs play a pivotal role in modulating the cell cycle, stemness, epithelial-mesenchymal transition (EMT), and resistance to targeted and chemoradiotherapy in HNSCC cells. This modulation occurs through interactions with secreted molecules or direct contact with the ECM or CAF. Co-culture and 3D models of tumour cells and other TME cell types allows to mimic the HNSCC tumour milieu and enable modulating tumour hypoxia and reprograming cancer stem cells (CSC). This review aims to provide an update on the development of HNSCC tumour models comprising CAFs to obtain better understanding of the interaction between CAFs and tumour cells, and for providing preclinical testing platforms of current and combination with emerging therapeutics.

HPV18 E7 inhibits LATS1 kinase and activates YAP1 by degrading PTPN14

High-risk human papillomavirus (HPV) oncoproteins inactivate cellular tumor suppressors to reprogram host cell signaling pathways. HPV E7 proteins bind and degrade the tumor suppressor PTPN14, thereby promoting the nuclear localization of the YAP1 oncoprotein and inhibiting keratinocyte differentiation. YAP1 is a transcriptional coactivator that drives epithelial cell stemness and self-renewal. YAP1 activity is inhibited by the highly conserved Hippo pathway, which is frequently inactivated in human cancers. MST1/2 and LATS1/2 kinases form the core of the Hippo kinase cascade. Active LATS1 kinase is phosphorylated on threonine 1079 and inhibits YAP1 by phosphorylating it on amino acids including serine 127. Here, we tested the effect of high-risk (carcinogenic) HPV18 E7 on Hippo pathway activity. We found that either PTPN14 knockout or PTPN14 degradation by HPV18 E7 decreased phosphorylation of LATS1 T1079 and YAP1 S127 in human keratinocytes and inhibited keratinocyte differentiation. Conversely, PTPN14-dependent differentiation required LATS kinases and certain PPxY motifs in PTPN14. Neither MST1/2 kinases nor the putative PTPN14 phosphatase active site were required for PTPN14 to promote differentiation. Taken together, these data support that PTPN14 inactivation or degradation of PTPN14 by HPV18 E7 reduce LATS1 activity, promoting active YAP1 and inhibiting keratinocyte differentiation.

A review on decoding the roles of YAP/TAZ signaling pathway in cardiovascular diseases: Bridging molecular mechanisms to therapeutic insights

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) serve as transcriptional co-activators that dynamically shuttle between the cytoplasm and nucleus, resulting in either the suppression or enhancement of their downstream gene expression. Recent emerging evidence demonstrates that YAP/TAZ is strongly implicated in the pathophysiological processes that contribute to cardiovascular diseases (CVDs). In the cardiovascular system, YAP/TAZ is involved in the orchestration of a range of biological processes such as oxidative stress, inflammation, proliferation, and autophagy. Furthermore, YAP/TAZ has been revealed to be closely associated with the initiation and development of various cardiovascular diseases, including atherosclerosis, pulmonary hypertension, myocardial fibrosis, cardiac hypertrophy, and cardiomyopathy. In this review, we delve into recent studies surrounding YAP and TAZ, along with delineating their roles in contributing to the pathogenesis of CVDs with a link to various physiological processes in the cardiovascular system. Additionally, we highlight the current potential drugs targeting YAP/TAZ for CVDs therapy and discuss their challenges for translational application. Overall, this review may offer novel insights for understanding and treating cardiovascular disorders.

TPX2 overexpression promotes sensitivity to dasatinib in breast cancer by activating YAP transcriptional signaling

Chromosomal instability (CIN) is a hallmark of cancer aggressiveness, providing genetic plasticity and tumor heterogeneity that allows the tumor to evolve and adapt to stress conditions. CIN is considered a cancer therapeutic biomarker because healthy cells do not exhibit CIN. Despite recent efforts to identify therapeutic strategies related to CIN, the results obtained have been very limited. CIN is characterized by a genetic signature where a collection of genes, mostly mitotic regulators, are overexpressed in CIN-positive tumors, providing aggressiveness and poor prognosis. We attempted to identify new therapeutic strategies related to CIN genes by performing a drug screen, using cells that individually express CIN-associated genes in an inducible manner. We find that the overexpression of targeting protein for Xklp2 (TPX2) enhances sensitivity to the proto-oncogene c-Src (SRC) inhibitor dasatinib due to activation of the Yes-associated protein 1 (YAP) pathway. Furthermore, using breast cancer data from The Cancer Genome Atlas (TCGA) and a cohort of cancer-derived patient samples, we find that both TPX2 overexpression and YAP activation are present in a significant percentage of cancer tumor samples and are associated with poor prognosis; therefore, they are putative biomarkers for selection for dasatinib therapy.

Reversal of cisplatin resistance in oral squamous cell carcinoma by piperlongumine loaded smart nanoparticles through inhibition of Hippo-YAP signaling pathway

Cisplatin alone or in combination with 5FU and docetaxel is the preferred chemotherapy regimen for advanced-stage OSCC patients. However, its use has been linked to recurrence and metastasis due to the development of drug resistance. Therefore, sensitization of cancer cells to conventional chemotherapeutics can be an effective strategy to overcome drug resistance. Piperlongumine (PL), an alkaloid, have shown anticancer properties and sensitizes numerous neoplasms, but its effect on OSCC has not been explored. However, low aqueous solubility and poor pharmacokinetics limit its clinical application. Therefore, to improve its therapeutic efficacy, we developed piperlongumine-loaded PLGA-based smart nanoparticles (smart PL-NPs) that can rapidly release PL in an acidic environment of cancer cells and provide optimum drug concentrations to overcome chemoresistance. Our results revealed that smart PL-NPs has high cellular uptake in acidic environment, facilitating the intracellular delivery of PL and sensitizing cancer cells to cisplatin, resulting in synergistic anticancer activity in vitro by increasing DNA damage, apoptosis, and inhibiting drug efflux. Further, we have mechanistically explored the Hippo-YAP signaling pathway, which is the critical mediator of chemoresistance, and investigated the chemosensitizing effect of PL in OSCC. We observed that PL alone and in combination with cisplatin significantly inhibits the activation of YAP and its downstream target genes and proteins. In addition, the combination of cisplatin with smart PL-NPs significantly inhibited tumor growth in two preclinical models (patient-derived cell based nude mice and zebrafish xenograft). Taken together, our findings suggest that smart PL-NPs with cisplatin will be a novel formulation to reverse cisplatin resistance in patients with advanced OSCC.

Genetic dependencies associated with transcription factor activities in human cancer cell lines

Transcription factors (TFs) are important mediators of aberrant transcriptional programs in cancer cells. In this study, we focus on TF activity (TFa) as a biomarker for cell-line-selective anti-proliferative effects, in that high TFa predicts sensitivity to loss of function of a given gene (i.e., genetic dependencies [GDs]). Our linear-regression-based framework identifies 3,047 pan-cancer and 3,952 cancer-type-specific candidate TFa-GD associations from cell line data, which are then cross-examined for impact on survival in patient cohorts. One of the most prominent biomarkers is TEAD1 activity, whose associations with its predicted GDs are validated through experimental evidence as proof of concept. Overall, these TFa-GD associations represent an attractive resource for identifying innovative, biomarker-driven hypotheses for drug discovery programs in oncology.

Radiomic profiles improve prognostication and reveal targets for therapy in cervical cancer

Cervical cancer (CC) is a major global health problem with 570,000 new cases and 266,000 deaths annually. Prognosis is poor for advanced stage disease, and few effective treatments exist. Preoperative diagnostic imaging is common in high-income countries and MRI measured tumor size routinely guides treatment allocation of cervical cancer patients. Recently, the role of MRI radiomics has been recognized. However, its potential to independently predict survival and treatment response requires further clarification. This retrospective cohort study demonstrates how non-invasive, preoperative, MRI radiomic profiling may improve prognostication and tailoring of treatments and follow-ups for cervical cancer patients. By unsupervised clustering based on 293 radiomic features from 132 patients, we identify three distinct clusters comprising patients with significantly different risk profiles, also when adjusting for FIGO stage and age. By linking their radiomic profiles to genomic alterations, we identify putative treatment targets for the different patient clusters (e.g., immunotherapy, CDK4/6 and YAP-TEAD inhibitors and p53 pathway targeting treatments).

Leveraging the Fragment Molecular Orbital and MM-GBSA Methods in Virtual Screening for the Discovery of Novel Non-Covalent Inhibitors Targeting the TEAD Lipid Binding Pocket

The Hippo pathway controls organ size and homeostasis and is linked to numerous diseases, including cancer. The transcriptional enhanced associate domain (TEAD) family of transcription factors acts as a receptor for downstream effectors, namely yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), which binds to various transcription factors and is essential for stimulated gene transcription. YAP/TAZ-TEAD facilitates the upregulation of multiple genes involved in evolutionary cell proliferation and survival. TEAD1-4 overexpression has been observed in different cancers in various tissues, making TEAD an attractive target for drug development. The central drug-accessible pocket of TEAD is crucial because it undergoes a post-translational modification called auto-palmitoylation. Crystal structures of the C-terminal TEAD complex with small molecules are available in the Protein Data Bank, aiding structure-based drug design. In this study, we utilized the fragment molecular orbital (FMO) method, molecular dynamics (MD) simulations, shape-based screening, and molecular mechanics-generalized Born surface area (MM-GBSA) calculations for virtual screening, and we identified a novel non-covalent inhibitor-BC-001-with IC50 = 3.7 μM in a reporter assay. Subsequently, we optimized several analogs of BC-001 and found that the optimized compound BC-011 exhibited an IC50 of 72.43 nM. These findings can be used to design effective TEAD modulators with anticancer therapeutic implications.

TAZ is involved in breast cancer cell migration via regulating actin dynamics

Background

Cancer metastasis is dependent on cell migration. Several mechanisms, including epithelial-to-mesenchymal transition (EMT) and actin fiber formation, could be involved in cancer cell migration. As a downstream effector of the Hippo signaling pathway, transcriptional coactivator with PDZ-binding motif (TAZ) is recognized as a key mediator of the metastatic ability of breast cancer cells. We aimed to examine whether TAZ affects the migration of breast cancer cells through the regulation of EMT or actin cytoskeleton.

Methods

MCF-7 and MDA-MB-231 cells were treated with siRNA to attenuate TAZ abundance. Transwell migration assay and scratch wound healing assay were performed to study the effects of TAZ knockdown on cancer cell migration. Fluorescence microscopy was conducted to examine the vinculin and phalloidin. Semiquantitative immunoblotting and quantitative real-time PCR were performed to study the expression of small GTPases and kinases. Changes in the expression of genes associated with cell migration were examined through next-generation sequencing.

Results

TAZ-siRNA treatment reduced TAZ abundance in MCF-7 and MDA-MB-231 breast cancer cells, which was associated with a significant decrease in cell migration. TAZ knockdown increased the expression of fibronectin, but it did not exhibit the typical pattern of EMT progression. TGF-β treatment in MDA-MB-231 cells resulted in a reduction in TAZ and an increase in fibronectin levels. However, it paradoxically promoted cell migration, suggesting that EMT is unlikely to be involved in the decreased migration of breast cancer cells in response to TAZ suppression. RhoA, a small Rho GTPase protein, was significantly reduced in response to TAZ knockdown. This caused a decrease in the expression of the Rho-dependent downstream pathway, i.e., LIM kinase 1 (LIMK1), phosphorylated LIMK1/2, and phosphorylated cofilin, leading to actin depolymerization. Furthermore, myosin light chain kinase (MLCK) and phosphorylated MLC2 were significantly decreased in MDA-MB-231 cells with TAZ knockdown, inhibiting the assembly of stress fibers and focal adhesions.

Conclusion

TAZ knockdown inhibits the migration of breast cancer cells by regulating the intracellular actin cytoskeletal organization. This is achieved, in part, by reducing the abundance of RhoA and Rho-dependent downstream kinase proteins, which results in actin depolymerization and the disassembly of stress fibers and focal adhesions.

Amplification of Hippo Signaling Pathway Genes Is Governed and Implicated in the Serous Subtype-Specific Ovarian Carcino-Genesis

Among women, ovarian cancer ranks as the fifth most common cause of cancer-related deaths. This study examined the impact of Hippo signaling pathway on ovarian carcinogenesis. Therefore, the signatures related to Hippo signaling pathway were derived from the molecular signatures database (MSigDB) and were used for further analysis. The Z score-based pathway activation scoring method was employed to investigate the expression patterns of these signatures in the mRNA expression profiles of ovarian cancer cohorts. Compared to other subtype tumors, the results of this study show that the Hippo signaling pathway signatures are dysregulated prominently in serous subtype-specific ovarian carcinogenesis. A receiver operating characteristic (ROC) curve-based results of the Hippo gene set, yes-associated protein 1 (YAP1), and mammalian sterile 20-like kinases 1 (MST1) genes can predict the serous subtype tumors by higher specificity and sensitivity with significant areas under the curve values also further reconfirmed these signaling dysregulations. Moreover, these gene sets were studied further for mutation analysis in the profile of high-grade serous ovarian adenocarcinoma in the cBioPortal database. The OncoPrint results reveal that these Hippo signaling pathway genes are amplified highly during the grade three and stage third or fourth of serous type ovarian tumors. In addition, the results of the Dependency Map (DepMap) plot also clearly show that these genes are amplified significantly across the ovarian cancer cell lines. Finally, overall survival (OS) curve plot investigations also revealed that these gene expressions show poor survival patterns linked to highly expressed conditions in serous subtypes of ovarian cancer patients with significant p-values (p < 0.05). Thus, the current finding would help to develop the targeted therapies treatment for serous subtype ovarian carcinogenesis.

VGLL2 and TEAD1 fusion proteins drive YAP/TAZ-independent transcription and tumorigenesis by engaging p300

Studies on Hippo pathway regulation of tumorigenesis largely center on YAP and TAZ, the transcriptional co-regulators of TEAD. Here, we present an oncogenic mechanism involving VGLL and TEAD fusions that is Hippo pathway-related but YAP/TAZ-independent. We characterize two recurrent fusions, VGLL2-NCOA2 and TEAD1-NCOA2, recently identified in spindle cell rhabdomyosarcoma. We demonstrate that, in contrast to VGLL2 and TEAD1, the fusion proteins are strong activators of TEAD-dependent transcription, and their function does not require YAP/TAZ. Furthermore, we identify that VGLL2 and TEAD1 fusions engage specific epigenetic regulation by recruiting histone acetyltransferase p300 to control TEAD-mediated transcriptional and epigenetic landscapes. We showed that small molecule p300 inhibition can suppress fusion proteins-induced oncogenic transformation both in vitro and in vivo. Overall, our study reveals a molecular basis for VGLL involvement in cancer and provides a framework for targeting tumors carrying VGLL, TEAD, or NCOA translocations.

Extracellular vesicles in cancer therapy: Roles, potential application, and challenges

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer as they play important roles in cancer development and progression. Considering their natural capacity to facilitate cell-to-cell communication as well as their high physiochemical stability and biocompatibility, EVs serve as superior delivery systems for a wide range of therapeutic agents, including medicines, nanomaterials, nucleic acids, and proteins. Therefore, EVs-based cancer therapy is of greater interest to researchers. Mounting studies indicate that EVs can be improved in efficiency, specificity, and safety for cancer therapy. However, their heterogeneity of physicochemical properties and functions is not fully understood, hindering the achievement of bioactive EVs with high yield and purity. Herein, we paid more attention to the EVs applications and their significance in cancer therapy.

TRIM21 is critical in regulating hepatocellular carcinoma growth and response to therapy by altering the MST1/YAP pathway

Liver cancer is the sixth most common cancer and the third leading cause of cancer-related death globally. Despite efforts being made in last two decades in cancer diagnosis and treatment, the 5-year survival rate of liver cancer remains extremely low. TRIM21 participates in cancer metabolism, glycolysis, immunity, chemosensitivity and metastasis by targeting various substrates for ubiquitination. TRIM21 serves as a prognosis marker for human hepatocellular carcinoma (HCC), but the mechanism by which TRIM21 regulates HCC tumorigenesis and progression remains elusive. In this study, we demonstrated that TRIM21 protein levels were elevated in human HCC. Elevated TRIM21 expression was associated with HCC progression and poor survival. Knockdown of TRIM21 in HCC cell lines significantly impaired cell growth and metastasis and enhanced sorafenib-induced toxicity. Mechanistically, we found that knockdown of TRIM21 resulted in cytosolic translocation and inactivation of YAP. At the molecular level, we further identified that TRIM21 interacted and induced ubiquitination of MST1, which resulted in MST1 degradation and YAP activation. Knockdown of MST1 or overexpression of YAP reversed TRIM21 knockdown-induced impairment of HCC growth and chemosensitivity. Taken together, the current study demonstrates a novel mechanism that regulates the Hippo pathway and reveals TRM21 as a critical factor that promotes growth and chemoresistance in human HCC.

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

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

The alanyl-tRNA synthetase AARS1 moonlights as a lactyltransferase to promote YAP signaling in gastric cancer

Lactylation has been recently identified as a new type of posttranslational modification occurring widely on lysine residues of both histone and nonhistone proteins. The acetyltransferase p300 is thought to mediate protein lactylation, yet the cellular concentration of the proposed lactyl-donor, lactyl-coenzyme A, is about 1,000 times lower than that of acetyl-CoA, raising the question of whether p300 is a genuine lactyltransferase. Here, we report that alanyl-tRNA synthetase 1 (AARS1) moonlights as a bona fide lactyltransferase that directly uses lactate and ATP to catalyze protein lactylation. Among the candidate substrates, we focused on the Hippo pathway, which has a well-established role in tumorigenesis. Specifically, AARS1 was found to sense intracellular lactate and translocate into the nucleus to lactylate and activate the YAP-TEAD complex; and AARS1 itself was identified as a Hippo target gene that forms a positive-feedback loop with YAP-TEAD to promote gastric cancer (GC) cell proliferation. Consistently, the expression of AARS1 was found to be upregulated in GC, and elevated AARS1 expression was found to be associated with poor prognosis for patients with GC. Collectively, this work found AARS1 with lactyltransferase activity in vitro and in vivo and revealed how the metabolite lactate is translated into a signal of cell proliferation.

Integrative modeling and analysis of signaling crosstalk reveal molecular switches coordinating Yes-associated protein transcriptional activities

The transcriptional co-activator YAP forms complexes with distinct transcription factors, controlling cell fate decisions, such as proliferation and apoptosis. However, the mechanisms underlying its context-dependent function are poorly defined. This study explores the interplay between the TGF-β and Hippo pathways and their influence on YAP's association with specific transcription factors. By integrating iterative mathematical modeling with experimental validation, we uncover molecular switches, predominantly controlled by RASSF1A and ITCH, which dictate the formation of YAP-SMAD (proliferative) and YAP-p73 (apoptotic) complexes. Our results show that RASSF1A enhances the formation of apoptotic complexes, whereas ITCH promotes the formation of proliferative complexes. Notably, higher levels of ITCH transform YAP-SMAD activity from a transient to a sustained state, impacting cellular behaviors. Extending these findings to various breast cancer cell lines highlights the role of cellular context in YAP regulation. Our study provides new insights into the mechanisms of YAP transcriptional activities and their therapeutic implications.

Hippo cell signaling and HS-proteoglycans regulate tissue form and function, age-dependent maturation, extracellular matrix remodeling, and repair

This review examined how Hippo cell signaling and heparan sulfate (HS)-proteoglycans (HSPGs) regulate tissue form and function. Despite being a nonweight-bearing tissue, the brain is regulated by Hippo mechanoresponsive cell signaling pathways during embryonic development. HS-proteoglycans interact with growth factors, morphogens, and extracellular matrix components to regulate development and pathology. Pikachurin and Eyes shut (Eys) interact with dystroglycan to stabilize the photoreceptor axoneme primary cilium and ribbon synapse facilitating phototransduction and neurotransduction with bipolar retinal neuronal networks in ocular vision, the primary human sense. Another HSPG, Neurexin interacts with structural and adaptor proteins to stabilize synapses and ensure specificity of neural interactions, and aids in synaptic potentiation and plasticity in neurotransduction. HSPGs also stabilize the blood-brain barrier and motor neuron basal structures in the neuromuscular junction. Agrin and perlecan localize acetylcholinesterase and its receptors in the neuromuscular junction essential for neuromuscular control. The primary cilium is a mechanosensory hub on neurons, utilized by YES associated protein (YAP)-transcriptional coactivator with PDZ-binding motif (TAZ) Hippo, Hh, Wnt, transforming growth factor (TGF)-β/bone matrix protein (BMP) receptor tyrosine kinase cell signaling. Members of the glypican HSPG proteoglycan family interact with Smoothened and Patched G-protein coupled receptors on the cilium to regulate Hh and Wnt signaling during neuronal development. Control of glycosyl sulfotransferases and endogenous protease expression by Hippo TAZ YAP represents a mechanism whereby the fine structure of HS-proteoglycans can be potentially modulated spatiotemporally to regulate tissue morphogenesis in a similar manner to how Hippo signaling controls sialyltransferase expression and mediation of cell-cell recognition, dysfunctional sialic acid expression is a feature of many tumors.

Identification of a Gene Signature That Predicts Dependence upon YAP/TAZ-TEAD

Targeted therapies are effective cancer treatments when accompanied by accurate diagnostic tests that can help identify patients that will respond to those therapies. The YAP/TAZ-TEAD axis is activated and plays a causal role in several cancer types, and TEAD inhibitors are currently in early-phase clinical trials in cancer patients. However, a lack of a reliable way to identify tumors with YAP/TAZ-TEAD activation for most cancer types makes it difficult to determine which tumors will be susceptible to TEAD inhibitors. Here, we used a combination of RNA-seq and bioinformatic analysis of metastatic melanoma cells to develop a YAP/TAZ gene signature. We found that the genes in this signature are TEAD-dependent in several melanoma cell lines, and that their expression strongly correlates with YAP/TAZ activation in human melanomas. Using DepMap dependency data, we found that this YAP/TAZ signature was predictive of melanoma cell dependence upon YAP/TAZ or TEADs. Importantly, this was not limited to melanoma because this signature was also predictive when tested on a panel of over 1000 cancer cell lines representing numerous distinct cancer types. Our results suggest that YAP/TAZ gene signatures like ours may be effective tools to predict tumor cell dependence upon YAP/TAZ-TEAD, and thus potentially provide a means to identify patients likely to benefit from TEAD inhibitors.

Inhibition of the YAP-MMB interaction and targeting NEK2 as potential therapeutic strategies for YAP-driven cancers

YAP activation in cancer is linked to poor outcomes, making it an attractive therapeutic target. Previous research focused on blocking the interaction of YAP with TEAD transcription factors. Here, we took a different approach by disrupting YAP's binding to the transcription factor B-MYB using MY-COMP, a fragment of B-MYB containing the YAP binding domain fused to a nuclear localization signal. MY-COMP induced cell cycle defects, nuclear abnormalities, and polyploidization. In an AKT and YAP-driven liver cancer model, MY-COMP significantly reduced liver tumorigenesis, highlighting the importance of the YAP-B-MYB interaction in tumor development. MY-COMP also perturbed the cell cycle progression of YAP-dependent uveal melanoma cells but not of YAP-independent cutaneous melanoma cell lines. It counteracted YAP-dependent expression of MMB-regulated cell cycle genes, explaining the observed effects. We also identified NIMA-related kinase (NEK2) as a downstream target of YAP and B-MYB, promoting YAP-driven transformation by facilitating centrosome clustering and inhibiting multipolar mitosis.

LATS1 Promotes B-ALL Tumorigenesis by Regulating YAP1 Phosphorylation and Subcellular Localization

OBJECTIVE

YAP1 plays a dual role as an oncogene and tumor suppressor gene in several tumors; differentiating between these roles may depend on the YAP1 phosphorylation pattern. The specific function of YAP1 in B cell acute lymphoblastic leukemia (B-ALL), however, is currently unclear. Thus, in the present study, the role of YAP1 in B-ALL was investigated using relevant cell lines and patient datasets.

METHODS

The effects of shRNA-mediated knockdown on YAP1 and LATS1 levels in the NALM6 and MOLT-4 cell lines were examined using Western blotting, quantitative real-time polymerase chain reaction, flow cytometry, immunostaining, and nude mouse subcutaneous tumorigenesis experiments. Gene expression levels of Hippo pathway-related molecules before and after verteporfin (VP) treatment were compared using RNA-Seq to identify significant Hippo pathway-related genes in NALM6 cells.

RESULTS

Patients with ALL showing high YAP1 expression and low YAP1-Ser127 phosphorylation levels had worse prognoses than those with low YAP1 protein expression and high YAP1-Ser127 phosphorylation levels. YAP1-Ser127 phosphorylation levels were lower in NALM6 cells than in MOLT-4 and control cells; YAP1 was distributed in the nuclei in NALM6 cells. Knockdown of YAP1 inhibited MOLT-4 and NALM6 cell proliferation and arrested the NALM6 cell cycle in the G0/G1 phase. Before and after VP treatment, the expression of the upstream gene LATS1 was upregulated; its overexpression promoted YAP1-Ser127 phosphorylation. Further, YAP1 was distributed in the plasma.

CONCLUSION

LATS1 may downregulate YAP1-Ser127 phosphorylation and maintain B-ALL cell function; thus, VP, which targets this axis, may serve as a new therapeutic method for improving the outcomes for B-ALL patients.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

The LKB1-TSSK1B axis controls YAP phosphorylation to regulate the Hippo-YAP pathway

The Hippo pathway's main effector, Yes-associated protein (YAP), plays a crucial role in tumorigenesis as a transcriptional coactivator. YAP's phosphorylation by core upstream components of the Hippo pathway, such as mammalian Ste20 kinase 1/2 (MST1/2), mitogen-activated protein kinase kinase kinase kinases (MAP4Ks), and their substrate, large tumor suppressor 1/2 (LATS1/2), influences YAP's subcellular localization, stability, and transcriptional activity. However, recent research suggests the existence of alternative pathways that phosphorylate YAP, independent of these core upstream Hippo pathway components, raising questions about additional means to inactivate YAP. In this study, we present evidence demonstrating that TSSK1B, a calcium/calmodulin-dependent protein kinase (CAMK) superfamily member, is a negative regulator of YAP, suppressing cellular proliferation and oncogenic transformation. Mechanistically, TSSK1B inhibits YAP through two distinct pathways. Firstly, the LKB1-TSSK1B axis directly phosphorylates YAP at Ser94, inhibiting the YAP-TEAD complex's formation and suppressing its target genes' expression. Secondly, the TSSK1B-LATS1/2 axis inhibits YAP via phosphorylation at Ser127. Our findings reveal the involvement of TSSK1B-mediated molecular mechanisms in the Hippo-YAP pathway, emphasizing the importance of multilevel regulation in critical cellular decision-making processes.

A chaperone-like function of FUS ensures TAZ condensate dynamics and transcriptional activation

The Hippo pathway has important roles in organ development, tissue homeostasis and tumour growth. Its downstream effector TAZ is a transcriptional coactivator that promotes target gene expression through the formation of biomolecular condensates. However, the mechanisms that regulate the biophysical properties of TAZ condensates to enable Hippo signalling are not well understood. Here using chemical crosslinking combined with an unbiased proteomics approach, we show that FUS associates with TAZ condensates and exerts a chaperone-like effect to maintain their proper liquidity and robust transcriptional activity. Mechanistically, the low complexity sequence domain of FUS targets the coiled-coil domain of TAZ in a phosphorylation-regulated manner, which ensures the liquidity and dynamicity of TAZ condensates. In cells lacking FUS, TAZ condensates transition into gel-like or solid-like assembles with immobilized TAZ, which leads to reduced expression of target genes and inhibition of pro-tumorigenic activity. Thus, our findings identify a chaperone-like function of FUS in Hippo regulation and demonstrate that appropriate biophysical properties of transcriptional condensates are essential for gene activation.

Regulation of Hippo-YAP/CTGF signaling by combining an HDAC inhibitor and 5-fluorouracil in gastric cancer cells

Histone deacetylase (HDAC) inhibitors diminish carcinogenesis, metastasis, and cancer cell proliferation by inducing death in cancer cells. Tissue regeneration and organ development are highly dependent on the Hippo signaling pathway. Targeting the dysregulated hippo pathway is an excellent approach for cancer treatment. According to the results of this study, the combination of panobinostat, a histone deacetylase inhibitor, and 5-fluorouracil (5-FU), a chemotherapy drug, can act synergistically to induce apoptosis in gastric cancer cells. The combination of panobinostat and 5-FU was more effective in inhibiting cell viability than either treatment alone by elevating the protein levels of cleaved PARP and cleaved caspase-9. By specifically targeting E-cadherin, vimentin, and MMP-9, the combination of panobinostat and 5-FU significantly inhibited cell migration. Additionally, panobinostat significantly increased the anticancer effects of 5-FU by activating Hippo signaling (Mst 1 and 2, Sav1, and Mob1) and inhibiting the Akt signaling pathway. As a consequence, there was a decrease in the amount of Yap protein. The combination therapy of panobinostat with 5-FU dramatically slowed the spread of gastric cancer in a xenograft animal model by deactivating the Akt pathway and supporting the Hippo pathway. Since combination treatment exhibits much higher anti-tumor potential than 5-FU alone, panobinostat effectively potentiates the anti-tumor efficacy of 5-FU. As a result, it is believed that panobinostat and 5-FU combination therapy will be useful as supplemental chemotherapy in the future.

Molecular Insight into Gastric Cancer Invasion-Current Status and Future Directions

Gastric cancer (GC) is one of the most common malignancies worldwide. There has been no efficient therapy for stage IV GC patients due to this disease's heterogeneity and dissemination ability. Despite the rapid advancement of molecular targeted therapies, such as HER2 and immune checkpoint inhibitors, survival of GC patients is still unsatisfactory because the understanding of the mechanism of GC progression is still incomplete. Invasion is the most important feature of GC metastasis, which causes poor mortality in patients. Recently, genomic research has critically deepened our knowledge of which gene products are dysregulated in invasive GC. Furthermore, the study of the interaction of GC cells with the tumor microenvironment has emerged as a principal subject in driving invasion and metastasis. These results are expected to provide a profound knowledge of how biological molecules are implicated in GC development. This review summarizes the advances in our current understanding of the molecular mechanism of GC invasion. We also highlight the future directions of the invasion therapeutics of GC. Compared to conventional therapy using protease or molecular inhibitors alone, multi-therapy targeting invasion plasticity may seem to be an assuring direction for the progression of novel strategies.

RHOAL57V drives the development of diffuse gastric cancer through IGF1R-PAK1-YAP1 signaling

Cancer-associated mutations in the guanosine triphosphatase (GTPase) RHOA are found at different locations from the mutational hotspots in the structurally and biochemically related RAS. Tyr42-to-Cys (Y42C) and Leu57-to-Val (L57V) substitutions are the two most prevalent RHOA mutations in diffuse gastric cancer (DGC). RHOAY42C exhibits a gain-of-function phenotype and is an oncogenic driver in DGC. Here, we determined how RHOAL57V promotes DGC growth. In mouse gastric organoids with deletion of Cdh1, which encodes the cell adhesion protein E-cadherin, the expression of RHOAL57V, but not of wild-type RHOA, induced an abnormal morphology similar to that of patient-derived DGC organoids. RHOAL57V also exhibited a gain-of-function phenotype and promoted F-actin stress fiber formation and cell migration. RHOAL57V retained interaction with effectors but exhibited impaired RHOA-intrinsic and GAP-catalyzed GTP hydrolysis, which favored formation of the active GTP-bound state. Introduction of missense mutations at KRAS residues analogous to Tyr42 and Leu57 in RHOA did not activate KRAS oncogenic potential, indicating distinct functional effects in otherwise highly related GTPases. Both RHOA mutants stimulated the transcriptional co-activator YAP1 through actin dynamics to promote DGC progression; however, RHOAL57V additionally did so by activating the kinases IGF1R and PAK1, distinct from the FAK-mediated mechanism induced by RHOAY42C. Our results reveal that RHOAL57V and RHOAY42C drive the development of DGC through distinct biochemical and signaling mechanisms.

Antitumor Effect of Berberine Analogs in a Canine Mammary Tumor Cell Line and in Zebrafish Reporters via Wnt/β-Catenin and Hippo Pathways

The heterogeneous nature of human breast cancer (HBC) can still lead to therapy inefficacy and high lethality, and new therapeutics as well as new spontaneous animal models are needed to benefit translational HBC research. Dogs are primarily investigated since they spontaneously develop tumors that share many features with human cancers. In recent years, different natural phytochemicals including berberine, a plant alkaloid, have been reported to have antiproliferative activity in vitro in human cancers and rodent animal models. In this study, we report the antiproliferative activity and mechanism of action of berberine, its active metabolite berberrubine, and eight analogs, on a canine mammary carcinoma cell line and in transgenic zebrafish models. We demonstrate both in vitro and in vivo the significant effects of specific analogs on cell viability via the induction of apoptosis, also identifying their role in inhibiting the Wnt/β-catenin pathway and activating the Hippo signals with a downstream reduction in CTGF expression. In particular, the berberine analogs NAX035 and NAX057 show the highest therapeutic efficacy, deserving further analyses to elucidate their mechanism of action more in detail, and in vivo studies on spontaneous neoplastic diseases are needed, aiming at improving veterinary treatments of cancer as well as translational cancer research.

Development of HC-258, a Covalent Acrylamide TEAD Inhibitor That Reduces Gene Expression and Cell Migration

The transcription factor YAP-TEAD is the downstream effector of the Hippo pathway which controls cell proliferation, apoptosis, tissue repair, and organ growth. Dysregulation of the Hippo pathway has been correlated with carcinogenic processes. A co-crystal structure of TEAD with its endogenous ligand palmitic acid (PA) as well as with flufenamic acid (FA) has been disclosed. Here we report the development of HC-258, which derives from FA and possesses an oxopentyl chain that mimics a molecule of PA as well as an acrylamide that reacts covalently with TEAD's cysteine. HC-258 reduces the CTGF, CYR61, AXL, and NF2 transcript levels and inhibits the migration of MDA-MB-231 breast cancer cells. Co-crystallization with hTEAD2 confirmed that HC-258 binds within TEAD's PA pocket, where it forms a covalent bond with its cysteine.

Unleashing the Power of Yes-Associated Protein in Ferroptosis and Drug Resistance in Breast Cancer, with a Special Focus on Therapeutic Strategies

The YAP protein is a critical oncogenic mediator within the Hippo signaling pathway and has been implicated in various cancer types. In breast cancer, it frequently becomes activated, thereby contributing to developing drug-resistance mechanisms. Recent studies have underscored the intricate interplay between YAP and ferroptosis within the breast tumor microenvironment. YAP exerts a negative regulatory effect on ferroptosis, promoting cancer cell survival and drug resistance. This review offers a concise summary of the current understanding surrounding the interplay between the YAP pathway, ferroptosis, and drug-resistance mechanisms in both bulk tumor cells and cancer stem cells. We also explore the potential of natural compounds alone or in combination with anticancer therapies for targeting the YAP pathway in treating drug-resistant breast cancer. This approach holds the promise of enhancing the effectiveness of current treatments and paving the way for developing novel therapeutics.

Delivery of SAV-siRNA via Exosomes from Adipose-Derived Stem Cells for the Treatment of Myocardial Infarction

BACKGROUND

Myocardial infarction (MI) leads to cardiomyocyte death, poor cardiac remodeling, and heart failure, making it a major cause of mortality and morbidity. To restore cardiac pumping function, induction of cardiomyocyte regeneration has become a focus of academic interest. The Hippo pathway is known to regulate cardiomyocyte proliferation and heart size, and its inactivation allows adult cardiomyocytes to re-enter the cell cycle.

METHODS

In this study, we investigated whether exosomes from adipose-derived stem cells (ADSCs) could effectively transfer siRNA for the Hippo pathway regulator Salvador (SAV) into cardiomyocytes to induce cardiomyocyte regeneration in a mouse model of MI.

RESULTS

Our results showed that exosomes loaded with SAV-siRNA effectively transferred siRNA into cardiomyocytes and induced cardiomyocyte re-entry into the cell cycle, while retaining the previously demonstrated therapeutic efficacy of ADSC-derived exosomes to improve post-infarction cardiac function through anti-fibrotic, pro-angiogenic, and other effects.

CONCLUSIONS

Our findings suggest that siRNA delivery via ADSC-derived exosomes may be a promising approach for the treatment of MI.

Verteporfin Suppresses YAP-Induced Glycolysis in Breast Cancer Cells

OBJECTIVE

The inhibition of the Hippo pathway through targeting the Yes-associated protein (YAP) presents a novel and promising approach for treating tumors. However, the efficacy of YAP inhibitors in the context of breast cancer (BC) remains incompletely understood. Here, we aimed to investigate the involvement of YAP in BC's metabolic reprogramming and reveal the potential underlying mechanisms. To this end, we assessed the function of verteporfin (VP), a YAP-TEAD complex inhibitor, on the glycolytic activity of BC cells.

METHODS

We evaluated the expression of YAP by utilizing immunohistochemistry (IHC) in BC patients who have undergone 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) prior to biopsy/surgery. We employed RNA immunoprecipitation (RIP) and fluorescent in situ hybridization (FISH) assays to assess the interaction between YAP mRNA and human antigen R (HuR) in BC cells. The biological importance of YAP in the metabolism and malignancy of BC was evaluated in vitro. Finally, the effect of VP on glycolysis was determined by using 18F-FDG uptake, glucose consumption, and lactate production assays.

RESULTS

Our studies revealed that high expression of YAP was positively correlated with the maximum uptake value (SUVmax) determined by 18F-FDG PET/CT imaging in BC samples. Inhibition of YAP activity suppressed glycolysis in BC. The mechanism underlying this phenomenon could be the binding of YAP to HuR, which promotes glycolysis in BC cells. Treatment with VP effectively suppressed glycolysis induced by YAP overexpression in BC cells.

CONCLUSION

VP exhibited anti-glycolytic effect on BC cells, indicating its therapeutic value as an FDA-approved drug.

MEX3A determines in vivo hepatocellular carcinoma progression and induces resistance to sorafenib in a Hippo-dependent way

BACKGROUND

Hepatocellular carcinoma (HCC) is most common malignant tumor worldwide, and one of the most lethal malignancies. MEX3A, RNA-binding protein, is profoundly implicated in tumor initiation and progression. But its role and potential mechanism in HCC remains fully unclear.

METHODS

The expression of MEX3A in HCC was analysis using the data derived from the Cancer Genome Atlas (TCGA) dataset and further confirmed by HCC samples and cells lines. The roles of MEX3A in the proliferation, migration and sorafenib resistance were detected both in vitro and vivo. In addition, the underline mechanism was investigated.

RESULTS

In this study, MEX3A expression was upregulated in HCC tissue and cell lines. Knockdown or overexpression of MEX3A disturbed the proliferation, migration and apoptosis of HCC cells by modulating the activation of Hippo signaling pathway. The expression of MEX3A was negatively associated with sorafenib sensitivity and upregulated in sorafenib resistant HCC cells. MEX3A knockdown facilitated the expression of WWC1, a negative modulator of Hippo signaling pathway, and led to increase of the phosphorylation of LATS1 and YAP1. Pharmacological inhibition of LATS1 or WWC1 overexpression alleviated the proliferative and migrated suppression and increased sorafenib sensitivity, whereas WWC1 inhibition using genetic interference strategy showed opposite trend in MEX3A knockdown HCC cells. Importantly, MEX3A knockdown led to growth and lung metastasis inhibition using xenograft model established by means of subcutaneous or tail vein injection. In addition, a combination of MEX3A knockdown and WWC1 overexpression dramatically enhances the growth inhibition of sorafenib in vivo.

CONCLUSION

MEX3A may facilitate HCC progression and hinder sorafenib sensitivity via inactivating Hippo signaling. The present study suggested that targeting MEX3A can be served as a novel therapeutic strategy for HCC.

Coagulation factor VIIa enhances programmed death-ligand 1 expression and its stability in breast cancer cells to promote breast cancer immune evasion

BACKGROUND

Immunotherapy for breast cancer has not gained significant success. Coagulation factor VIIa (FVIIa)-tissue factor (TF) mediated activation of protease-activated receptor 2 (PAR2) is shown to promote metastasis and secretion of the immune-modulatory cytokines but the role of FVIIa in cancer immunology is still not well understood.

OBJECTIVES

Here, we aim to investigate whether FVIIa protects breast cancer cells from CD8 T-cell-mediated killing.

METHODS

Peripheral blood mononuclear cell-derived CD8 T cells were cocultured with vehicle or FVIIa pretreated MDAMB468 cells. The proliferation and activity of CD8 T cells were measured by flow cytometry and ELISA. An allograft model, using wild-type or TF/PAR2-deleted 4T1 cells, was employed to determine the effect of FVIIa on breast cancer immune evasion in vivo.

RESULTS

Here, we demonstrate that TF-FVIIa induces programmed death-ligand 1 (PD-L1) in breast cancer cells by activating PAR2. PAR2 activation triggers large tumor suppressor kinase 1 (LATS1) inactivation leading to loss of yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) phosphorylation and subsequent nuclear localization of YAP/TAZ. YAP/TAZ inhibition reduces PD-L1 expression and increases CD8 T-cell activity. We further demonstrate that, apart from transcriptional induction of PD-L1, PAR2 activation also increases PD-L1 stability by enhancing its glycosylation through N-glycosyltransferases STT3A and STT3B.

CONCLUSION

In a mouse model of breast cancer, tumor cell-specific PAR2 depletion leads to PD-L1 downregulation and increases anti-PD-1 immunotherapy efficacy. In conclusion, we showed that FVIIa-mediated signaling cascade in cancer cells serves as a tumor intrinsic mechanism of immunosuppression to promote cancer immune evasion.

Unveiling the role of hypoxic macrophage-derived exosomes in driving colorectal cancer progression

The crosstalk between tumor cells and macrophages under hypoxic conditions has been acknowledged as a pivotal determinant in the progression of colorectal cancer (CRC). Previous research has underscored the significance of exosomes derived from hypoxic tumor cells in facilitating tumor progression through inducing the polarization of macrophages towards the M2-like phenotype. The precise influence of hypoxic macrophage-derived exosomes (HMDEs) on the progression of CRC has not yet been fully elucidated. The objective of this study was to investigate the role of HMDEs in the progression of CRC. We discovered that there was an elevated release of exosomes derived from macrophages in hypoxic conditions. Additionally, the hypoxia-induced macrophage-derived exosomes played a crucial role in promoting the progression of CRC. We have also demonstrated that HMDEs have the ability to induce cell cycle transition and inhibit cell apoptosis, thereby promoting the growth of CRC cells. Furthermore, the underlying molecular mechanisms of these effects have been identified. The overexpression of Hif-1α results in its direct interaction with distinct regions (-521- -516 bp and -401- -391 bp) of the Hsp90 promoter during hypoxic circumstances. This binding event led to the overexpression of Hsp90 and the subsequent elevation of Hsp90 protein levels within HMDEs. Importantly, the crucial interaction between Hsp90 and Lats1 resulted in the deactivation of Lats1 and the inhibition of Yap phosphorylation. Ultimately, this series of events lead to the deactivation of the Hippo signaling pathway. Our in vivo and in vitro studies presented compelling evidence for the crucial role of hypoxic macrophage-derived exosomal Hsp90 in promoting CRC progression through the inhibition of the Hippo signaling pathway. These findings represented a significant advancement in our comprehension of the complex interplay between macrophages and CRC cells under hypoxic conditions.

The role of non-canonical Hippo pathway in regulating immune homeostasis

The Hippo pathway is a crucial signaling pathway that is highly conserved throughout evolution for the regulation of organ size and maintenance of tissue homeostasis. Initial studies have primarily focused on the canonical Hippo pathway, which governs organ development, tissue regeneration, and tumorigenesis. In recent years, extensive research has revealed that the non-canonical Hippo pathway, centered around Mst1/2 as its core molecule, plays a pivotal role in immune response and function by synergistically interacting with other signal transduction pathways. Consequently, the non-canonical Hippo pathway assumes significant importance in maintaining immune system homeostasis. This review concentrates on the research progress of the non-canonical Hippo pathway in regulating innate immune cell anti-infection responses, maintaining redox homeostasis, responding to microenvironmental stiffness, and T-cell differentiation.

The human adenovirus E1B-55K oncoprotein coordinates cell transformation through regulation of DNA-bound host transcription factors

The multifunctional adenovirus E1B-55K oncoprotein can induce cell transformation in conjunction with adenovirus E1A gene products. Previous data from transient expression studies and in vitro experiments suggest that these growth-promoting activities correlate with E1B-55K-mediated transcriptional repression of p53-targeted genes. Here, we analyzed genome-wide occupancies and transcriptional consequences of species C5 and A12 E1B-55Ks in transformed mammalian cells by combinatory ChIP and RNA-seq analyses. E1B-55K-mediated repression correlates with tethering of the viral oncoprotein to p53-dependent promoters via DNA-bound p53. Moreover, we found that E1B-55K also interacts with and represses transcription of numerous p53-independent genes through interactions with transcription factors that play central roles in cancer and stress signaling. Our results demonstrate that E1B-55K oncoproteins function as promiscuous transcriptional repressors of both p53-dependent and -independent genes and further support the model that manipulation of cellular transcription is central to adenovirus-induced cell transformation and oncogenesis.

Development of LM-41 and AF-2112, two flufenamic acid-derived TEAD inhibitors obtained through the replacement of the trifluoromethyl group by aryl rings

The Hippo pathway regulates organ size and tissue homeostasis by controlling cell proliferation and apoptosis. The YAP-TEAD transcription factor, the downstream effector of the Hippo pathway, regulates the expression of genes such as CTGF, Cyr61, Axl and NF2. Aberrant Hippo activity has been identified in multiple types of cancers. Flufenamic acid (FA) was reported to bind in a liphophilic TEAD palmitic acid (PA) pocket, leading to reduction of the expression of Axl and NF2. Here, we show that the replacement of the trifluoromethyl moiety in FA by aromatic groups, directly connected to the scaffold or separated by a linker, leads to compounds with better affinity to TEAD. Co-crystallization studies show that these compounds bind similarly to FA, but deeper within the PA pocket. Our studies identified LM-41 and AF-2112 as two TEAD binders that strongly reduce the expression of CTGF, Cyr61, Axl and NF2. LM-41 gave the strongest reduction of migration of human MDA-MB-231 breast cancer cells.

Extract2Chip-Bypassing Protein Purification in Drug Discovery Using Surface Plasmon Resonance

Modern drug discovery relies on combinatorial screening campaigns to find drug molecules targeting specific disease-associated proteins. The success of such campaigns often relies on functional and structural information of the selected therapeutic target, only achievable once its purification is mastered. With the aim of bypassing the protein purification process to gain insights on the druggability, ligand binding, and/or characterization of protein-protein interactions, herein, we describe the Extract2Chip method. This approach builds on the immobilization of site-specific biotinylated proteins of interest, directly from cellular extracts, on avidin-coated sensor chips to allow for the characterization of molecular interactions via surface plasmon resonance (SPR). The developed method was initially validated using Cyclophilin D (CypD) and subsequently applied to other drug discovery projects in which the targets of interest were difficult to express, purify, and crystallize. Extract2Chip was successfully applied to the characterization of Yes-associated protein (YAP): Transcriptional enhancer factor TEF (TEAD1) protein-protein interaction inhibitors, in the validation of a ternary complex assembly composed of Dyskerin pseudouridine synthase 1 (DKC1) and RuvBL1/RuvBL2, and in the establishment of a fast-screening platform to select the most suitable NUAK family SNF1-like kinase 2 (NUAK2) surrogate for binding and structural studies. The described method paves the way for a potential revival of the many drug discovery campaigns that have failed to deliver due to the lack of suitable and sufficient protein supply.

ADCY6 is a potential prognostic biomarker and suppresses OTSCC progression via Hippo signaling pathway

Oral tongue squamous cell carcinoma (OTSCC) is a malignant tumor. Recently, studies have found that adenylate cyclase 6 (ADCY6) plays a pivotal role in many lethal tumors formation processes. The role of ADCY6 in OTSCC remains unknown. The expression of ADCY6 in OTSCC tissue samples was detected. The clinical significance of ADCY6 in OTSCC was analyzed by statistical methods. OTSCC cell lines were selected to analyze the biological function of ADCY6. Meanwhile, the effect of ADCY6 on the growth of OTSCC in vivo was explored using subcutaneous tumorigenesis assay. WB assay was used to detect the underlying signaling pathway. Cell function recovery test used to investigate the mechanism of ADCY6-promoting OTSCC malignant biological behavior via Hippo signaling pathway. We report that ADCY6 was obviously downregulated in OTSCC tissue samples and cell lines. Importantly, lower expression of ADCY6 indicates a poorer prognosis in patients with OTSCC, and its expression is significantly correlated with TNM stage and tumor size. Functionally, forced expression of ADCY6 can significantly inhibit the proliferation, migration, invasion, and promote apoptosis of OTSCC cells. Mechanistically, we demonstrated that ADCY6 upregulation impaired Hippo signaling pathway to reduce the malignant biological behavior of OTSCC. Generally, our findings suggest that ADCY6 suppressed Hippo signaling pathway to regulate malignant biological behavior in OTSCC, which provide new cues for further exploring the mechanism of occurrence and development of OTSCC.

RGS16 regulates Hippo-YAP activity to promote esophageal cancer cell proliferation and migration

Esophageal Squamous Cell Carcinoma (ESCC) is a common malignant tumor of digestive tract, accounting for 90% of all pathological types of esophageal cancer. Despite the rapid development of multi-disciplinary treatment such as surgery, chemotherapy, radiotherapy and chemoradiotherapy, the prognosis of patients with ESCC is still poor. Regulators of G-protein signaling (RGSs) are involved in the processes of various cancers. The expression levels of its family member RGS16 are abnormally elevated in a variety of tumors, but its role in ESCC is still unclear. We found that RGS16 expression is aberrantly increased in ESCC tissues and correlated with poor prognosis of ESCC patients from The Cancer Genome Atlas (TCGA) database and our collected ESCC tissues. Moreover, knockdown of RGS16 in two ESCC cells could indeed inhibit their proliferation and migration. We further explored the molecular mechanism of RGS16 in ESCC, and the correlation analysis from TCGA database showed that the mRNA levels of RGS16 was positively correlated with that of CTGF and CYR61, two target genes of Hippo-YAP signaling. Consistently, RGS16- knockdown significantly inhibited the expression of CTGF and CYR61 in ESCC cells. We found that the phosphorylation levels of LATS1 and YAP were significantly increased and YAP translocated into the cytoplasm after depletion of RGS16 in ESCC cells. Also, RGS16-knockdown promoted the interaction between LATS1 and upstream kinase MST1. In addition, reintroduction of a constitutive active YAP5A mutant significantly rescued CTGF expression and cell proliferation in RGS16-knockdown cells. Together, our work revealed that RGS16 promoted YAP activity through disrupting the interaction between LATS1 and MST1, thus promoting the proliferation and migration of ESCC cells.

Thioridazine protects against disturbed flow-induced atherosclerosis by inhibiting RhoA/YAP-mediated endothelial inflammation

Atherosclerotic diseases remain the leading cause of adult mortality and impose heavy burdens on health systems globally. Our previous study found that disturbed flow enhanced YAP activity to provoke endothelial activation and atherosclerosis, and targeting YAP alleviated endothelial inflammation and atherogenesis. Therefore, we established a luciferase reporter assay-based drug screening platform to seek out new YAP inhibitors for anti-atherosclerotic treatment. By screening the FDA-approved drug library, we identified that an anti-psychotic drug thioridazine markedly suppressed YAP activity in human endothelial cells. Thioridazine inhibited disturbed flow-induced endothelial inflammatory response in vivo and in vitro. We verified that the anti-inflammatory effects of thioridazine were mediated by inhibition of YAP. Thioridazine regulated YAP activity via restraining RhoA. Moreover, administration of thioridazine attenuated partial carotid ligation- and western diet-induced atherosclerosis in two mouse models. Overall, this work opens up the possibility of repurposing thioridazine for intervention of atherosclerotic diseases. This study also shed light on the underlying mechanisms that thioridazine inhibited endothelial activation and atherogenesis via repression of RhoA-YAP axis. As a new YAP inhibitor, thioridazine might need further investigation and development for the treatment of atherosclerotic diseases in clinical practice.

PIP5Kγ Mediates PI(4,5)P2/Merlin/LATS1 Signaling Activation and Interplays with Hsc70 in Hippo-YAP Pathway Regulation

The type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family produces the critical lipid regulator phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in the plasma membrane (PM). Here, we investigated the potential role of PIP5Kγ, a PIP5K isoform, in the Hippo pathway. The ectopic expression of PIP5Kγ87 or PIP5Kγ90, two major PIP5Kγ splice variants, activated large tumor suppressor kinase 1 (LATS1) and inhibited Yes-associated protein (YAP), whereas PIP5Kγ knockdown yielded opposite effects. The regulatory effects of PIP5Kγ were dependent on its catalytic activity and the presence of Merlin and LATS1. PIP5Kγ knockdown weakened the restoration of YAP phosphorylation upon stimulation with epidermal growth factor or lysophosphatidic acid. We further found that PIP5Kγ90 bound to the Merlin's band 4.1/ezrin/radixin/moesin (FERM) domain, forming a complex with PI(4,5)P2 and LATS1 at the PM. Notably, PIP5Kγ90, but not its kinase-deficient mutant, potentiated Merlin-LATS1 interaction and recruited LATS1 to the PM. Consistently, PIP5Kγ knockdown or inhibitor (UNC3230) enhanced colony formation in carcinoma cell lines YAP-dependently. In addition, PIP5Kγ90 interacted with heat shock cognate 71-kDa protein (Hsc70), which also contributed to Hippo pathway activation. Collectively, our results suggest that PIP5Kγ regulates the Hippo-YAP pathway by forming a functional complex with Merlin and LATS1 at the PI(4,5)P2-rich PM and via interplay with Hsc70.