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

Characterization of open chromatin sensitive to actin polymerization and identification of core-binding factor subunit beta as mechanosensitive nucleocytoplasmic shuttling protein

Mechanotransduction leads to a variety of biological responses including gene expression, changes in cell shape, migration, tissue development, and immune responses. Dysregulation of mechanotransduction is implicated in the progression of various diseases such as cardiovascular diseases and cancer. The actin cytoskeleton plays a crucial role in transmitting mechanical stimuli. Actin filaments, essential for cell motility and shape changes, respond to mechanical cues by remodeling, influencing gene expression via the linker of nucleoskeleton and cytoskeleton complex and mechanosensitive transcription factors. This study employs the dithiobis(succinimidyl propionate) (DSP)-micrococcal nuclease (MNase) proteogenomics method to explore the relationship between cellular mechanosensing, chromatin architecture, and the identification of proteins involved in mechanosensitive nucleocytoplasmic shuttling, revealing how actin polymerization affects chromatin and gene expression. We found that depolymerization of actin filaments by latrunculin B (Lat B) for 30 min is sufficient to alter open chromatin and identified core-binding factor subunit beta as mechanosensitive nucleocytoplasmic shuttling protein.

A novel clinically relevant antagonistic interplay between prolactin and oncogenic YAP-CCN2 pathways as a differentiation therapeutic target in breast cancer

Cellular differentiation limits cellular plasticity allowing cells to attain their specialized functional characteristics and phenotypes, whereas loss of differentiation is a hallmark of cancer. Thus, characterizing mechanisms underlying differentiation is key to discover new cancer therapeutics. We report a novel functional antagonistic relationship between the prolactin (PRL)/prolactin receptor (PRLR) differentiation pathway and YAP-CCN2 oncogenic pathway in normal mammary epithelial cells and breast cancer cells that is essential for establishing/maintaining acinar morphogenesis, cell-cell junctions and the intracellular localization of apical-basal polarity protein complexes (Par, Crumb and Scrib). Importantly, using CRISPR knockout of the PRLR in MCF7, HR+ breast cancer cells, further revealed that the negative relationship between PRL/PRLR pathway and YAP-CCN2 pathway is critical in suppressing luminal-to-basal stem-like lineage plasticity. Furthermore, the clinical relevance of this interplay was evaluated using bioinformatics approaches on several human datasets, including samples from normal breast epithelium, breast cancer, and 33 other cancer types. This analysis revealed a positive correlation between PRLR and the YAP suppressor Hippo pathway and a co-expression gene network driving favourable patients' survival outcomes in breast cancer. The therapeutic potential of this interplay was also evaluated in vitro using MDA-MB-231 cells, a preclinical model of human triple-negative breast cancer, where treatment with PRL and Verteporfin, an FDA-approved pharmacological YAP-inhibitor, alone or their combination suppressed the expression of the mesenchymal marker vimentin and the stem cell marker CD44 as well as reduced their Ki67 proliferative marker expression. Collectively, our results emphasize the pro-differentiation role of PRL/PRLR pathway in mammary and breast cancer cells and highlight that promoting PRL/PRLR signaling while inhibiting the YAP-CCN2 oncogenic pathway can be exploited as a differentiation-based combination therapeutic strategy in breast cancer.

Fibrosis: cross-organ biology and pathways to development of innovative drugs

Fibrosis is a pathophysiological mechanism involved in chronic and progressive diseases that results in excessive tissue scarring. Diseases associated with fibrosis include metabolic dysfunction-associated steatohepatitis (MASH), inflammatory bowel diseases (IBDs), chronic kidney disease (CKD), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc), which are collectively responsible for substantial morbidity and mortality. Although a few drugs with direct antifibrotic activity are approved for pulmonary fibrosis and considerable progress has been made in the understanding of mechanisms of fibrosis, translation of this knowledge into effective therapies continues to be limited and challenging. With the aim of assisting developers of novel antifibrotic drugs, this Review integrates viewpoints of biologists and physician-scientists on core pathways involved in fibrosis across organs, as well as on specific characteristics and approaches to assess therapeutic interventions for fibrotic diseases of the lung, gut, kidney, skin and liver. This discussion is used as a basis to propose strategies to improve the translation of potential antifibrotic therapies.

PTPRO represses breast cancer lung metastasis by inhibiting the JAK2-YAP axis

Lung metastasis is the primary cause of breast cancer-related mortality. Protein tyrosine phosphatases such as PTPRO are important in cancer progression. However, the role and underlying mechanisms of PTPRO in breast cancer lung metastasis are largely unknown. The function of PTPRO in breast cancer metastasis was examined in mice with ptpro deficiency driven by the PyMT promoter. The regulatory role of PTPRO in JAK2-YAP activation was tested in cell-based knockdown, overexpression and catalytic-dead mutation assays. Bioinformatics analyses and assays of human cancer specimens and mouse tumour samples were performed to investigate PTPRO-regulated pathways and functions. Ptpro deletion in MMTV-PyMT transgenic mice led to increased lung metastasis. Bioinformatics analyses and subsequent assays of human breast cancer specimens revealed a reverse correlation between PTPRO expression and JAK2-YAP pathway activity. Both in vitro and in vivo data demonstrated that PTPRO inactivates the JAK2-YAP pathway and diminishes the metastatic ability of breast cancer. Analysis of catalytic-dead PTPRO mutant breast cancer cells confirmed that functional PTPRO is a determinant of the activation of the JAK2-YAP pathway and the suppression of breast cancer metastasis. Data from patient, animal and cell-based models collectively demonstrated that PTPRO suppresses breast cancer lung metastasis by inhibiting JAK2-YAP dephosphorylation. Therefore, strengthening PTPRO or targeting PTPRO-mediated pathways could be potential strategies for inhibiting breast cancer lung metastasis.

Mesenchymal Hippo signaling regulates intestinal homeostasis in adult mice

Intestinal homeostasis is tightly regulated by the reciprocal interaction between the gut epithelium and adjacent mesenchyme. The Hippo pathway is intimately associated with intestinal epithelial homeostasis and regeneration; however, its role in postnatal gut mesenchyme remains poorly defined. Here, we find that removal of the core Hippo kinases Lats1/2 or activation of YAP in adult intestinal smooth muscle layers has largely no effect; however, Hippo-YAP signaling in the niche-forming Gli1+ mesenchymal cells plays intrinsic roles in regulating intestinal homeostasis. We find that Lats1/2 deletion drives robust mesenchymal over-proliferation, and YAP activation in Gli1+ pericryptal cells disrupts the intestinal epithelial-mesenchymal crosstalk via promoting Wnt ligand production. We show that YAP is upregulated in the stroma during dextran sodium sulfate (DSS)-induced injury, and mesenchymal YAP activation facilitates intestinal epithelial regeneration. Altogether, our data suggest an important role for mesenchymal Hippo-YAP signaling in the stem cell niche during intestinal homeostasis and pathogenesis.

VGLL2 and TEAD1 fusion proteins drive YAP/TAZ-independent 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.

Cell enlargement modulated by GATA4 and YAP instructs the senescence-associated secretory phenotype

Dynamic changes in cell size are associated with development and pathological conditions, including aging. Although cell enlargement is a prominent morphological feature of cellular senescence, its functional implications are unknown; moreover, how senescent cells maintain their enlargement state is less understood. Here we show that an extensive remodeling of actin cytoskeleton is necessary for establishing senescence-associated cell enlargement and pro-inflammatory senescence-associated secretory phenotype (SASP). This remodeling is attributed to a balancing act between the SASP regulator GATA4 and the mechanosensor YAP on the expression of the Rho family of GTPase RHOU. Genetic or pharmacological interventions that reduce cell enlargement attenuate SASP with minimal effect on senescence growth arrest. Mechanistically, actin cytoskeleton remodeling couples cell enlargement to the nuclear localization of GATA4 and NF-κB via the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. RhoU protein accumulates in mouse adipose tissue under senescence-inducing conditions. Furthermore, RHOU expression correlates with SASP expression in adipose tissue during human aging. Thus, our study highlights an unexpected instructive role of cell enlargement in modulating the SASP and reveals a mechanical branch in the senescence regulatory network.

Unveiling the potential of biomechanics in pioneering innovative strategies for cancer therapy

Mechanical force transmission is pivotal in tumor biology, profoundly affecting cancer cell behaviors such as proliferation, metastasis, and resistance to therapy. To explore novel biomechanical-based therapeutic strategies for cancer treatment, this paper deciphers the advances in biomechanical measurement approaches and the impact of biomechanical signals on fundamental oncological processes such as tumor microenvironment remodeling, angiogenesis, metastasis, and drug resistance. Then, the mechanisms of biomechanical signal transduction of tumor cells are demonstrated to identify novel targets for tumor therapy. Additionally, this study proposes a novel tumor treatment strategy, the biomechanical regulation tumor nanotherapeutics, including smart biomaterials designed to disturb mechanical signaling pathways and innovative nanodrugs that interfere transduction of biomechanical signals to improve tumor therapeutic outcomes. These methods mark a departure from conventional pharmacological therapies to novel strategies that utilize mechanical forces to impede tumor progression and enhance tumor responsiveness to treatment. In general, this review highlights the critical role of biomechanical signals in cancer biology from a holistic perspective and underscores the potential of biomechanical interventions as a transformative class of therapeutics. By integrating mechanobiology into the development of cancer treatments, this paper paves the way for more precise and effective strategies that leverage the inherent physical properties of the tumor microenvironment.

YAP/TAZ-associated cell signaling - at the crossroads of cancer and neurodevelopmental disorders

YAP/TAZ (Yes-associated protein/paralog transcriptional co-activator with PDZ-binding domain) are transcriptional cofactors that are the key and major downstream effectors of the Hippo signaling pathway. Both are known to play a crucial role in defining cellular outcomes, including cell differentiation, cell proliferation, and apoptosis. Aside from the canonical Hippo signaling cascade with the key components MST1/2 (mammalian STE20-like kinase 1/2), SAV1 (Salvador homologue 1), MOB1A/B (Mps one binder kinase activator 1A/B) and LATS1/2 (large tumor suppressor kinase 1/2) upstream of YAP/TAZ, YAP/TAZ activation is also influenced by numerous other signaling pathways. Such non-canonical regulation of YAP/TAZ includes well-known growth factor signaling pathways such as the epidermal growth factor receptor (EGFR)/ErbB family, Notch, and Wnt signaling as well as cell-cell adhesion, cell-matrix interactions and mechanical cues from a cell's microenvironment. This puts YAP/TAZ at the center of a complex signaling network capable of regulating developmental processes and tissue regeneration. On the other hand, dysregulation of YAP/TAZ signaling has been implicated in numerous diseases including various cancers and neurodevelopmental disorders. Indeed, in recent years, parallels between cancer development and neurodevelopmental disorders have become apparent with YAP/TAZ signaling being one of these pathways. This review discusses the role of YAP/TAZ in brain development, cancer and neurodevelopmental disorders with a special focus on the interconnection in the role of YAP/TAZ in these different conditions.

METTL3-dependent DLG2 inhibits the malignant progression of cervical cancer by inactivating the Hippo/YAP signaling

BACKGROUND

Discs large homolog 2 (DLG2) has been implicated in cancer development, yet its role in cervical cancer remains unclear. This study aims to explore the regulatory mechanism of DLG2 in cervical cancer and its clinical implications.

METHODS

Quantitative reverse transcription polymerase chain reaction and western blotting assays were employed to detect RNA and protein expression, respectively. Colony formation assay, 5-Ethynyl-2'-deoxyuridine assay, flow cytometry, and transwell assays were conducted for cell functional analysis. A xenograft mouse model assay was performed to analyze tumor tumorigenesis in vivo. m6A RNA immunoprecipitation assay was used to analyze the association of METTL3 and DLG2.

RESULTS

DLG2 was underexpressed in cervical cancer tissues and cells. Elevating DLG2 levels significantly suppressed cervical cancer cell proliferation, migration, and invasion, while promoting apoptosis. Additionally, DLG2 overexpression led to the deactivation of the Hippo/YAP signaling pathway. In vivo, DLG2 overexpression was shown to reduce tumor formation. We also discovered that METTL3 destabilized DLG2 mRNA through an m6A-dependent mechanism. Moreover, lowering DLG2 expression mitigated the effects of METTL3 silencing on cervical cancer cell malignancy.

CONCLUSION

DLG2 acted as a tumor suppressor in cervical cancer by inhibiting the Hippo/YAP signaling pathway. The METTL3-dependent regulation of DLG2 mRNA stability could be a critical factor in cervical cancer progression.

Deciphering mechanical cues in the microenvironment: from non-malignant settings to tumor progression

The tumor microenvironment functions as a dynamic and intricate ecosystem, comprising a diverse array of cellular and non-cellular components that precisely orchestrate pivotal tumor behaviors, including invasion, metastasis, and drug resistance. While unraveling the intricate interplay between the tumor microenvironment and tumor behaviors represents a tremendous challenge, recent research illuminates a crucial biological phenomenon known as cellular mechanotransduction. Within the microenvironment, mechanical cues like tensile stress, shear stress, and stiffness play a pivotal role by activating mechanosensitive effectors such as PIEZO proteins, integrins, and Yes-associated protein. This activation initiates cascades of intrinsic signaling pathways, effectively linking the physical properties of tissues to their physiological and pathophysiological processes like morphogenesis, regeneration, and immunity. This mechanistic insight offers a novel perspective on how the mechanical cues within the tumor microenvironment impact tumor behaviors. While the intricacies of the mechanical tumor microenvironment are yet to be fully elucidated, it exhibits distinct physical attributes from non-malignant tissues, including elevated solid stresses, interstitial hypertension, augmented matrix stiffness, and enhanced viscoelasticity. These traits exert notable influences on tumor progression and treatment responses, enriching our comprehension of the multifaceted nature of the microenvironment. Through this innovative review, we aim to provide a new lens to decipher the mechanical attributes within the tumor microenvironment from non-malignant contexts, broadening our knowledge on how these factors promote or inhibit tumor behaviors, and thus offering valuable insights to identify potential targets for anti-tumor strategies.

Yes-associated protein plays oncogenic roles in human sporadic colorectal adenomas

The role of Hippo-Yes-associated protein (YAP) in human colorectal cancer (CRC) presents contradictory results. We examined the function of YAP in the early stages of CRC by quantitatively measuring the expression of phospho-YAPS127 (p-YAP) and five APC-related proteins in 145 sporadic adenomas from the Tennessee Colorectal Polyp Study, conducting APC sequencing for 114 adenomas, and analyzing YAP-correlated cancer pathways using gene expression data from 326 adenomas obtained from Gene Expression Omnibus. The p-YAP expression was significantly correlated with YAP expression (r = 0.53, P < .0001) and nuclear β-catenin (r = 0.26, P = .0018) in adenoma tissues. Both p-YAP and nuclear β-catenin were associated with APC mutations (P = .05). A strong association was observed between p-YAP overexpression and advanced adenoma odds (OR = 12.62, 95% CI = 4.57-34.86, P trend < .001), which persisted after adjusting for covariates and biomarkers (OR = 12.31, 95% CI = 3.78-40.10, P trend < .0001). P-YAP exhibited a sensitivity of 77.4% and specificity of 78.2% in defining advanced versus nonadvanced adenomas. Additionally, synergistic interaction was noted between p-YAP positivity and nuclear β-catenin on advanced adenomas (OR = 16.82, 95% CI = 4.41-64.08, P < .0001). YAP-correlated genes were significantly enriched in autophagy, unfolded protein response, and sirtuin pathways showing predominantly pro-tumorigenic alterations. Collectively, YAP plays an oncogenic role in interacting with Wnt as well as other cancer pathways within human sporadic adenomas. P-YAP could be a potential biomarker for human high-risk sporadic adenomas.

miR-424-5p Promotes Proliferation, Migration and Invasion of Colorectal Cancer Cells via the Targeting TXNIP/Hippo Axi

Background

Aggressive biological behavior leads to unfavorable survival of colorectal cancer (CRC) patients. Dysregulation of TXNIP has been reported to be associated with the occurrence, proliferation and metastasis of malignancies such as liver cancer, lung cancer, kidney cancer, gastric cancer, and pancreatic cancer. MiR-424-5p has been reported as a negative regulator of TXNIP involved in lipopolysaccharide-induced acute kidney injury. And disordered Hippo pathway and YAP/TAZ-TEAD activity are related to tumor progression. The study was designed to clarify the function of miR-424-5p and thioredoxin interacting protein (TXNIP) in the progression of CRC.

Methods

The expression pattern of TXNIP and miR-424-5p was detected by immunohistochemistry, qRT-PCR and/or Western blotting. CCK-8 assays and transwell assays were applied to investigate the effect of TXNIP and miR-424-5p on cell proliferation, invasion and migration. Luciferase reporter assays were used to verify the transcriptional regulation among TXNIP, miR-424-5p and Hippo signaling pathway.

Results

TXNIP was poorly expressed whereas miR-424-5p was highly expressed in CRC tissues and cells. TXNIP overexpression suppressed proliferation, invasion and migration of CRC cells. It also suppressed the malignant behavior of the CRC cells promoted by miR-424-5p. Mechanically, TXNIP overexpression significantly inhibited YAP/TAZ transcriptional activity, and the highly expressed miR-424-5p in CRC targeted TXNIP mRNA.

Conclusion

The study clarify a novel miR-424-5p/TXNIP/Hippo signaling pathway that facilitated CRC cells proliferation, migration and invasion. The above findings suggested that miR-424-5p and TXNIP might serve as the potential therapeutic targets for CRC patients.

PSAT1 promotes the progression of colorectal cancer by regulating Hippo-YAP/TAZ-ID1 axis via AMOT

Colorectal cancer (CRC) ranks third for morbidity and second for mortality among all digestive malignant tumors worldwide, but its pathogenesis remains not entirely clear. Bioinformatic analyses were performed to find out important biomarkers for CRC. For validation, reverse transcription-quantitative PCR, western blotting, and immunohistochemistry were performed. Then, cell transfection, gain- and loss-of-function assays, immunofluorescence, cell line RNA-sequencing and analyses, and in vivo tumorigenesis assay were also performed to further explore the mechanism. We prioritized phosphoserine aminotransferase 1 (PSAT1) as an important biomarker in CRC. PSAT1 expression was gradually up-regulated as the CRC disease progresses and may relate to poor prognosis. PSAT1 promoted the malignant behaviors of CRC cells. Although PSAT1 is an enzyme essential to serine biosynthesis, an exogenous supplement of serine did not completely rescue the malignant behaviors in PSAT1-knockdown CRC cells. Interestingly, PSAT1 inhibited the Hippo tumor-suppressor pathway by promoting the nucleus-localization of YAP/TAZ and increasing the expression of ID1 in CRC cells. Furthermore, AMOT, a vascular-related molecule that molecularly interacts with YAP/TAZ, was up-regulated upon PSAT1 knockdown in CRC cells. Knocking down AMOT partially rescued the inhibition of proliferation and the reduced nuclear localization of YAP/TAZ caused by PSAT1 knockdown in CRC cells. Moreover, PSAT1 was closely related to vascular-related pathways, in which AMOT might act as a mediator. Finally, PSAT1 promoted CRC proliferation by negatively regulating AMOT in vivo. PSAT1 could enhance the progression of colorectal cancer by regulating Hippo-YAP/TAZ-ID1 axis via AMOT, which is independent of the metabolic function of PSAT1.

Inhibition of thioredoxin reductase 1 sensitizes glucose-starved glioblastoma cells to disulfidptosis

Disulfidptosis is a recently identified form of cell death characterized by the aberrant accumulation of cellular disulfides. This process primarily occurs in glucose-starved cells expressing higher levels of SLC7A11 and has been proposed as a therapeutic strategy for cancers with hyperactive SCL7A11. However, the potential for inducing disulfidptosis through other mechanisms in cancers remains unclear. Here, we found that inhibiting thioredoxin reductase 1 (TrxR1), a key enzyme in the thioredoxin system, induces disulfidptosis in glioblastoma (GBM) cells. TrxR1 expression is elevated in GBM with activated transcriptional coactivator with PDZ-binding motif (TAZ) and correlates with poor prognosis. TrxR1 inhibitors induced GBM cell death that can be rescued by disulfide reducers but not by ROS scavengers or inhibitors of apoptosis, ferroptosis, or necroptosis. Glucose-starved cells, but not those deprived of oxygen or glutamine, increased TrxR1 expression in an NRF2-dependent manner and were more sensitive to TrxR1 inhibition-induced cell death. The dying cells initially exhibited highly dynamic lamellipodia, followed by actin cytoskeleton collapse. This process involved the accumulation of cytosolic peroxisomes and micropinocytic caveolae, as well as small gaps in the plasma membrane. Depletion of the WAVE complex component NCKAP1 partially rescued the cells, whereas Rac inhibition enhanced cell death. In an orthotopic xenograft GBM mouse model, TrxR1 depletion inhibited tumor growth and improved survival. Furthermore, cells undergoing TrxR1 inhibition exhibited features of immunogenic cell death. Therefore, this study suggests the potential of targeting TrxR1 as a therapeutic strategy in GBM.

Advances towards potential cancer therapeutics targeting Hippo signaling

Decades of research into the Hippo signaling pathway have greatly advanced our understanding of its roles in organ growth, tissue regeneration, and tumorigenesis. The Hippo pathway is frequently dysregulated in human cancers and is recognized as a prominent cancer signaling pathway. Hence, the Hippo pathway represents an ideal molecular target for cancer therapies. This review will highlight recent advancements in targeting the Hippo pathway for cancer treatment and discuss the potential opportunities for developing new therapeutic modalities.

Hydrogel models of pancreatic adenocarcinoma to study cell mechanosensing

Pancreatic adenocarcinoma (PDAC) is the predominant form of pancreatic cancer and one of the leading causes of cancer-related death worldwide, with an extremely poor prognosis after diagnosis. High mortality from PDAC arises partly due to late diagnosis resulting from a lack of early-stage biomarkers and due to chemotherapeutic drug resistance, which arises from a highly fibrotic stromal response known as desmoplasia. Desmoplasia alters tissue mechanics, which triggers changes in cell mechanosensing and leads to dysregulated transcriptional activity and disease phenotypes. Hydrogels are effective in vitro models to mimic mechanical changes in tissue mechanics during PDAC progression and to study the influence of these changes on mechanosensitive cell responses. Despite the complex biophysical changes that occur within the PDAC microenvironment, carefully designed hydrogels can very closely recapitulate these properties during PDAC progression. Hydrogels are relatively inexpensive, highly reproducible and can be designed in a humanised manner to increase their relevance for human PDAC studies. In vivo models have some limitations, including species-species differences, high variability, expense and legal/ethical considerations, which make hydrogel models a promising alternative. Here, we comprehensively review recent advancements in hydrogel bioengineering for developing our fundamental understanding of mechanobiology in PDAC, which is critical for informing advanced therapeutics.

KANK1 promotes breast cancer development by compromising Scribble-mediated Hippo activation

KANK1 is expressed in epithelial cells and connects focal adhesions with the adjacent cortical microtubule stabilizing complex. Although KANK1 was shown to suppress cancer cell growth in vitro, TCGA database points to high KANK1 levels associated with poor prognosis in a wide spectrum of human malignancies. Here, we address this discrepancy and report that KANK1 promotes proliferation and survival of PyMT-transformed mammary tumor cells in vivo. Mechanistically, KANK1 localizes to the basal side of basement membrane (BM)-attached transformed luminal epithelial cells. When these cells lose the contact with the BM and disassemble integrin adhesions, KANK1 is found at cell-cell junctions where it competes with the polarity and tumor suppressor Scribble for NOS1AP binding, which curbs the ability of Scribble to promote Hippo pathway activity. The consequences are stabilization and nuclear accumulation of TAZ, growth and survival of tumor cells and elevated breast cancer development.

YAP1 Inhibition Induces Phenotype Switching of Cancer-Associated Fibroblasts to Tumor Suppressive in Prostate Cancer

Prostate cancer rarely responds to immune-checkpoint blockade (ICB) therapies. Cancer-associated fibroblasts (CAF) are critical components of the immunologically "cold" tumor microenvironment and are considered a promising target to enhance the immunotherapy response. In this study, we aimed to reveal the mechanisms regulating CAF plasticity to identify potential strategies to switch CAFs from protumorigenic to antitumor phenotypes and to enhance ICB efficacy in prostate cancer. Integration of four prostate cancer single-cell RNA sequencing datasets defined protumorigenic and antitumor CAFs, and RNA-seq, flow cytometry, and a prostate cancer organoid model demonstrated the functions of two CAF subtypes. Extracellular matrix-associated CAFs (ECM-CAF) promoted collagen deposition and cancer cell progression, and lymphocyte-associated CAFs (Lym-CAF) exhibited an antitumor phenotype and induced the infiltration and activation of CD8+ T cells. YAP1 activity regulated the ECM-CAF phenotype, and YAP1 silencing promoted switching to Lym-CAFs. NF-κB p65 was the core transcription factor in the Lym-CAF subset, and YAP1 inhibited nuclear translocation of p65. Selective depletion of YAP1 in ECM-CAFs in vivo promoted CD8+ T-cell infiltration and activation and enhanced the therapeutic effects of anti-PD-1 treatment on prostate cancer. Overall, this study revealed a mechanism regulating CAF identity in prostate cancer and highlighted a therapeutic strategy for altering the CAF subtype to suppress tumor growth and increase sensitivity to ICB. Significance: YAP1 regulates cancer-associated fibroblast phenotypes and can be targeted to switch cancer-associated fibroblasts from a protumorigenic subtype that promotes extracellular matrix deposition to a tumor-suppressive subtype that stimulates antitumor immunity and immunotherapy efficacy.

Evidence that CRISPR-Cas9 Y537S-mutant expressing breast cancer cells activate Yes-associated protein 1 to driving the conversion of normal fibroblasts into cancer-associated fibroblasts

BACKGROUND

Endocrine therapy (ET) has improved the clinical outcomes of Estrogen receptor alpha-positive (ERɑ +) breast cancer (BC) patients, even though resistance to ET remains a clinical issue. Mutations in the hormone-binding domain of ERɑ represent an acquired intrinsic mechanism of ET resistance. However, the latter also depends on the multiple functional interactions between BC cells and the tumor microenvironment (TME). Here, we investigated how the most common Y537S-ERɑ mutation may influence the behavior of fibroblasts, the most prominent component of the TME.

METHODS

We conducted coculture experiments with normal human foreskin fibroblasts BJ1-hTERT (NFs), cancer-associated fibroblasts (CAFs), isolated from human BC specimens, and Y537S CRISPR-expressing MCF-7 BC cells (MCF-7YS). Mass spectrometry (MS) and Metacore analyses were performed to investigate how the functional interactions between BC cells/fibroblasts may affect their proteomic profile. The impact of fibroblasts on BC tumor growth and metastatic potential was evaluated in nude mice.

RESULTS

Mutant BC conditioned medium (CM) affected the morphology/proliferation/migration of both NFs and CAFs. 198 deregulated proteins signed the proteomic similarity profile of NFs exposed to the YS-CM and CAFs. Among the upregulated proteins, Yes-associated protein 1 (YAP1) was the main central hub in the direct interaction network. Increased YAP1 protein expression and activity were confirmed in NFs treated with MCF-7YS-CM. However, YAP1 activation appears to crosstalk with the insulin growth factor-1 receptor (IGF-1R). Higher amount of IGF-1 were noticed in the MCF-7YS-CM cells compared to the MCF-7P, and IGF-1 immunodepletion reversed the enhanced YAP1 expression and activity. Mutant cells upon exposure to the NF- and CAF-CM exhibited an enhanced proliferation/growth/migration/invasion compared to the MCF-7P. MCF-7YS cells when implanted with CAFs showed an early relative increased tumor volume compared to YS alone. No changes were observed when MCF-7P cells were co-implanted with CAFs. Compared with that in MCF-7P cells, the metastatic burden of MCF-7YS cells was intrinsically greater, and this effect was augmented upon treatment with NF-CM and further increased with CAF-CM.

CONCLUSIONS

YS mutant BC cells induced the conversion of fibroblasts into CAFs, via YAP, which represent a potential therapeutic target which interrupt the functional interactions between mutant cells/TME and to be implemented in the novel therapeutic strategy of a subset of metastatic BC patients carrying the frequent Y537S mutations.

Dysregulation of deubiquitinases in gastric cancer progression

Gastric cancer (GC), characterized by a high incidence rate, poses significant clinical challenges owing to its poor prognosis despite advancements in diagnostic and therapeutic approaches. Therefore, a comprehensive understanding of the molecular mechanisms driving GC progression is crucial for identifying predictive markers and defining treatment targets. Deubiquitinating enzymes (DUBs), also called deubiquitinases, function as reverse transcriptases within the ubiquitin-proteasome system to counteract protein degradation. Recent findings suggest that DUB dysregulation could be a crucial factor in GC pathogenesis. In this review, we examined recent research findings on DUBs in the context of GC, elucidating their molecular characteristics, categorizations, and roles while also exploring the potential mechanisms underlying their dysregulation in GC. Furthermore, we assessed the therapeutic efficacy of DUB inhibitors in treating malignancies and evaluated the prevalence of aberrant DUB expression in GC.

Trilobatin, a Novel Naturally Occurring Food Additive, Ameliorates Alcoholic Liver Disease in Mice: Involvement of Microbiota-Gut-Liver Axis and Yap/Nrf2 Signaling Pathway

Trilobatin, a novel natural food additive, exerts a protective effect on acute liver injury. However, whether Trilobatin can protect against alcoholic liver disease (ALD) has not been elucidated. This research is intended to ascertain the impact of Trilobatin on ALD in mice and decipher the potential underlying mechanisms. Lieber-DeCarli liquid alcohol diet was used to induce ALD in mice, followed by administration of Trilobatin (10, 20, 40 mg·kg-1·d-1) for 15 days. The results suggested that Trilobatin significantly alleviated ethanol-induced hepatic injury in mice. Furthermore, RNA-Seq analysis revealed that yes-associated protein (YAP) downregulation occurred in the liver after Trilobatin treatment. Mechanistically, Trilobatin directly bound to YAP and hindered its nuclear translocation, which activated the Nrf2 pathway to reduce pro-inflammatory cytokines and oxidative stress. Intriguingly, 16S rDNA analysis results revealed that Trilobatin reshaped the gut microbiota, reducing harmful bacteria and increasing beneficial bacteria. It also enhanced tight junction proteins, defending against damage to the intestinal barrier. These findings not only highlight the microbiota-gut-liver axis and YAP/Nrf2 pathway as crucial potential targets to treat ALD but also reveal that Trilobatin effectively protects against ALD, at least partly, through modulating the microbiota-gut-liver axis and YAP/Nrf2 pathway.

Emerging role and function of Hippo-YAP/TAZ signaling pathway in musculoskeletal disorders

Hippo pathway is an evolutionarily conservative key pathway that regulates organ size and tissue regeneration by regulating cell proliferation, differentiation and apoptosis. Yes-associated protein 1 (YAP)/ WW domain-containing transcription regulator 1 (TAZ) serves as a pivotal transcription factor within the Hippo signaling pathway, which undergoes negative regulation by the Hippo pathway. The expression of YAP/TAZ affects various biological processes, including differentiation of osteoblasts (OB) and osteoclasts (OC), cartilage homeostasis, skeletal muscle development, regeneration and quality maintenance. At the same time, the dysregulation of the Hippo pathway can concurrently contribute to the development of various musculoskeletal disorders, including bone tumors, osteoporosis (OP), osteoarthritis (OA), intervertebral disc degeneration (IDD), muscular dystrophy, and rhabdomyosarcoma (RMS). Therefore, targeting the Hippo pathway has emerged as a promising therapeutic strategy for the treatment of musculoskeletal disorders. The focus of this review is to elucidate the mechanisms by which the Hippo pathway maintains homeostasis in bone, cartilage, and skeletal muscle, while also providing a comprehensive summary of the pivotal role played by core components of this pathway in musculoskeletal diseases. The efficacy and feasibility of Hippo pathway-related drugs for targeted therapy of musculoskeletal diseases are also discussed in our study. These endeavors offer novel insights into the application of Hippo signaling in musculoskeletal disorders, providing effective therapeutic targets and potential drug candidates for treating such conditions.

Identification of Gαi3 as a promising molecular oncotarget of pancreatic cancer

The increasing mortality rate of pancreatic cancer globally necessitates the urgent identification for novel therapeutic targets. This study investigated the expression, functions, and mechanistic insight of G protein inhibitory subunit 3 (Gαi3) in pancreatic cancer. Bioinformatics analyses reveal that Gαi3 is overexpressed in human pancreatic cancer, correlating with poor prognosis, higher tumor grade, and advanced classification. Elevated Gαi3 levels are also confirmed in human pancreatic cancer tissues and primary/immortalized cancer cells. Gαi3 shRNA or knockout (KO) significantly reduced cell viability, proliferation, cell cycle progression, and mobility in primary/immortalized pancreatic cancer cells. Conversely, Gαi3 overexpression enhanced pancreatic cancer cell growth. RNA-sequencing and bioinformatics analyses of Gαi3-depleted cells indicated Gαi3's role in modulating the Akt-mTOR and PKA-Hippo-YAP pathways. Akt-S6 phosphorylation was decreased in Gαi3-depleted cells, but was increased with Gαi3 overexpression. Additionally, Gαi3 depletion elevated PKA activity and activated the Hippo pathway kinase LATS1/2, leading to YAP/TAZ inactivation, while Gαi3 overexpression exerted the opposite effects. There is an increased binding between Gαi3 promoter and the transcription factor TCF7L2 in pancreatic cancer tissues and cells. Gαi3 expression was significantly decreased following TCF7L2 silencing, but increased with TCF7L2 overexpression. In vivo, intratumoral injection of Gαi3 shRNA-expressing adeno-associated virus significantly inhibited subcutaneous pancreatic cancer xenografts growth in nude mice. A significant growth reduction was also observed in xenografts from Gαi3 knockout pancreatic cancer cells. Akt-mTOR inactivation and increased PKA activity coupled with YAP/TAZ inactivation were also detected in xenograft tumors upon Gαi3 depletion. Furthermore, bioinformatic analysis and multiplex immunohistochemistry (mIHC) staining on pancreatic cancer tissue microarrays showed a reduced proportion of M1-type macrophages and an increase in PD-L1 positive cells in Gαi3-high pancreatic cancer tissues. Collectively, these findings highlight Gαi3's critical role in promoting pancreatic cancer cell growth, potentially through the modulation of the Akt-mTOR and PKA-Hippo-YAP pathways and its influence on the immune landscape.

Pannexin 1 crosstalk with the Hippo pathway in malignant melanoma

In this study, we explored the intricate relationship between Pannexin 1 (PANX1) and the Hippo signaling pathway effector, Yes-associated protein (YAP). Analysis of The Cancer Genome Atlas (TCGA) data revealed a significant positive correlation between PANX1 mRNA and core Hippo components, YAP, TAZ, and Hippo scaffold, IQGAP1, in invasive cutaneous melanoma and breast carcinoma. Furthermore, we demonstrated that PANX1 expression is upregulated in invasive melanoma cell lines and is associated with increased YAP protein levels. Notably, our investigations uncovered a previously unrecognized interaction between endogenous PANX1 and the Hippo scaffold protein IQGAP1 in melanoma cells. Moreover, our findings revealed that IQGAP1 exhibits differential expression in melanoma cells and plays a regulatory role in cellular morphology. Functional studies involving PANX1 knockdown provided compelling evidence that PANX1 modulates YAP protein levels and its co-transcriptional activity in both melanoma and breast carcinoma cells. Importantly, our study showcases the potential therapeutic relevance of targeting PANX1, as pharmacological inhibition of PANX1 using selective FDA-approved inhibitors or PANX1 knockdown reduced YAP abundance in melanoma cells. Furthermore, our Clariom™ S analysis unveiled key genes implicated in cell proliferation, such as neuroglin1 (NRG1), β-galactoside binding protein, galectin-3 (LGALS3), that are affected in PANX1-deficient cells. In summary, our investigation delves into the intricate interplay between PANX1 and YAP in the context of invasive melanoma, offering valuable insights into potential therapeutic strategies for effective treatment.

Synergistic effects of combined BET and FAK inhibition against Vestibular Schwannomas in NF2-related Schwannomatosis

Neurofibromatosis type 2 (NF2) is a rare disorder that causes vestibular schwannomas (VS), meningiomas and ependymomas. To date, there is no FDA approved drug-based treatment for NF2. We have previously identified that BET inhibition can selectively reduce growth of the NF2-null schwannoma and Schwann cells in vitro and tumorigenesis in vivo and, separately, reported that inhibition of Focal Adhesion Kinase 1 (FAK1) via crizotinib has antiproliferative effects in NF2-null Schwann cells. The current study was aimed at determining whether combined BET and FAK inhibition can synergize and to identify the mechanisms of action. A panel of normal and NF2-null Schwann and schwannoma cell lines were used to characterize the effects of combined BET and FAK inhibition in vitro and in vivo using pharmacological and genetic approaches. The mechanism of action was explored by chromatin immunoprecipitation, ChIP-PCR, western blotting, and functional approaches. We find that combined BET and FAK inhibition are synergistic and inhibit the proliferation of NF2-null schwannoma and Schwann cell lines in vitro and in vivo, by arresting cells in the G1/S and G2/M phases of the cell cycle. Further, we identify the mechanism of action through the downregulation of FAK1 transcription by BET inhibition, which potentiates inhibition of FAK by 100-fold. Our findings suggest that combined targeting of BET and FAK1 may offer a potential therapeutic option for the treatment of NF2-related schwannomas.

Retinoic acid-induced protein 14 links mechanical forces to Hippo signaling

Cells sense and respond to various mechanical forces from the extracellular matrix primarily by modulating the actin cytoskeleton. Mechanical forces can be translated into biochemical signals in a process called mechanotransduction. Yes-associated protein (YAP) is an effector of Hippo signaling and a mediator of mechanotransduction, but how mechanical forces regulate Hippo signaling is still an open question. We propose that retinoic acid-induced protein 14 (RAI14) responds to mechanical forces and regulates Hippo signaling. RAI14 positively regulates the activity of YAP. RAI14 interacts with NF2, a key component of the Hippo pathway, and the interaction occurs on filamentous actin. When mechanical forces are kept low in cells, NF2 dissociates from RAI14 and filamentous actin, resulting in increased interactions with LATS1 and activation of the Hippo pathway. Clinical data show that tissue stiffness and expression of RAI14 and YAP are upregulated in tumor tissues and that RAI14 is strongly associated with adverse outcome in patients with gastric cancer. Our data suggest that RAI14 links mechanotransduction with Hippo signaling and mediates Hippo-related biological functions such as cancer progression.

UBR1 promotes anaplastic thyroid carcinoma progression via stabilizing YAP through monoubiquitylation

Anaplastic thyroid carcinoma (ATC) is a highly aggressive human malignancy without effective treatment. Yes-associated protein (YAP) is a critical effector of the Hippo pathway, which is essential in thyroid carcinogenesis. However, the underlying mechanisms of aberrant YAP expression in ATC are not completely understood. Ubiquitylation-related enzyme siRNA screening identified the ubiquitin protein ligase E3 component n-recognin 1 (UBR1) as a stabilizer of YAP in ATC cells. UBR1 deficiency reduced YAP protein levels and its target gene expression. UBR1 directly interacted with YAP and promoted its monoubiquitylation, competitively suppressing its polyubiquitylation and resulting in extended protein half-life. UBR1 depletion reduced ATC cell proliferation and migration in vitro. Xenograft tumor studies also suggested that UBR1 knockdown suppressed ATC cell growth in vivo. Furthermore, exogenous YAP expression partially reversed the inhibitive effects of UBR1 depletion on ATC cell proliferation and migration. Our studies demonstrated that UBR1 directly interacts with YAP and stabilized it in a monoubiquitylation-dependent manner, consequently promoting ATC tumorigenesis, suggesting that UBR1 might be a potentially therapeutic target for ATC treatment.

Insights gained from computational modeling of YAP/TAZ signaling for cellular mechanotransduction

YAP/TAZ signaling pathway is regulated by a multiplicity of feedback loops, crosstalk with other pathways, and both mechanical and biochemical stimuli. Computational modeling serves as a powerful tool to unravel how these different factors can regulate YAP/TAZ, emphasizing biophysical modeling as an indispensable tool for deciphering mechanotransduction and its regulation of cell fate. We provide a critical review of the current state-of-the-art of computational models focused on YAP/TAZ signaling.

Complex interplay between RAS GTPases and RASSF effectors regulates subcellular localization of YAP

RAS GTPases bind effectors to convert upstream cues to changes in cellular function. Effectors of classical H/K/NRAS are defined by RBD/RA domains which recognize the GTP-bound conformation of these GTPases, yet the specificity of RBD/RAs for over 160 RAS superfamily proteins remains poorly explored. We have systematically mapped interactions between BRAF and four RASSF effectors, the largest family of RA-containing proteins, with all RAS, RHO and ARF small GTPases. 39 validated complexes reveal plasticity in RASSF binding, while BRAF demonstrates tight specificity for classical H/K/NRAS. Complex between RASSF5 and diverse RAS GTPases at the plasma membrane can activate Hippo signalling and sequester YAP in the cytosol. RASSF8 undergoes liquid-liquid phase separation and resides in YAP-associated membraneless condensates, which also engage several RAS and RHO GTPases. The poorly studied RASSF3 has been identified as a first potential effector of mitochondrial MIRO proteins, and its co-expression with these GTPases impacts mitochondria and peroxisome distribution. These data reveal the complex nature of GTPase-effector interactions and show their systematic elucidation can reveal completely novel and biologically relevant cellular processes.

YAP/TAZ-TEAD activity promotes the malignant transformation of cervical intraepithelial neoplasia through enhancing the characteristics and Warburg effect of cancer stem cells

A number of studies have confirmed that Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ)-transcriptional enhanced associate domain (TEAD) activity is the driver of cancer development. However, the role and mechanism of the YAP/TAZ-TEAD pathway in cervical intraepithelial neoplasia (CIN) remain to be clarified. Therefore, this study was designed to observe the effect of YAP/TAZ-TEAD activity on the development of CIN and provide new ideas for the diagnosis and treatment of CIN. Firstly, cervical tissues were collected from CIN patients in different stages [CIN grade 1 (CIN1) tissue, CIN grade 2/3 (CIN 2/3) and squamous cell carcinoma (SCC)] and healthy volunteers. Next, the expression levels of YAP, TAZ and TEAD in cervical tissues and cells were observed by immunohistochemistry, qRT-PCR and western blot. Besides, Z172 and Z183 cells were transfected with siRNA-YAP/TAZ (si-YAP/TAZ) and YAP/TAZ overexpression vector (YAP-5SA). Also, Z172 cells were co-transfected with YAP-5SA and si-TEAD2/4. Subsequently, the stemness characteristics, glycolysis level and malignant transformation of cells in each group were observed by sphere-formation assay, commercial kit, MTT, Transwell, scratch experiment, xenotransplantation and western blot.The expression of YAP, TAZ and TEAD increased significantly in cervical cancer tissue and cell line at the stage of CIN2/3 and SCC. When YAP/TAZ was knocked down, the stemness characteristics, glycolysis level and malignant transformation of cancer cells were notably inhibited; while activating YAP/TAZ exhibited a completely opposite result. In addition, activating YAP/TAZ and knocking down the TEAD expression at the same time significant weakened the effect of activated YAP/TAZ signal on precancerous cells and reduced inhibitory effect of knocking down TEAD alone. YAP/TAZ-TEAD signal activates the characteristics and Warburg effect of cancer stem cells, thereby promoting the malignant transformation of CIN.

The significant role of amino acid metabolic reprogramming in cancer

Amino acid metabolism plays a pivotal role in tumor microenvironment, influencing various aspects of cancer progression. The metabolic reprogramming of amino acids in tumor cells is intricately linked to protein synthesis, nucleotide synthesis, modulation of signaling pathways, regulation of tumor cell metabolism, maintenance of oxidative stress homeostasis, and epigenetic modifications. Furthermore, the dysregulation of amino acid metabolism also impacts tumor microenvironment and tumor immunity. Amino acids can act as signaling molecules that modulate immune cell function and immune tolerance within the tumor microenvironment, reshaping the anti-tumor immune response and promoting immune evasion by cancer cells. Moreover, amino acid metabolism can influence the behavior of stromal cells, such as cancer-associated fibroblasts, regulate ECM remodeling and promote angiogenesis, thereby facilitating tumor growth and metastasis. Understanding the intricate interplay between amino acid metabolism and the tumor microenvironment is of crucial significance. Expanding our knowledge of the multifaceted roles of amino acid metabolism in tumor microenvironment holds significant promise for the development of more effective cancer therapies aimed at disrupting the metabolic dependencies of cancer cells and modulating the tumor microenvironment to enhance anti-tumor immune responses and inhibit tumor progression.

Circular RNA circ_ARHGEF28 inhibits MST1/2 dimerization to suppress Hippo pathway to induce cisplatin resistance in ovarian cancer

BACKGROUND

Cisplatin is integral to ovarian cancer treatment, yet resistance to this drug often results in adverse patient outcomes. The association of circular RNA (circRNA) with cisplatin resistance in ovarian cancer has been observed, but the mechanisms governing this relationship require further elucidation.

METHODS

High-throughput sequencing was utilized to profile circRNA expression in cisplatin-resistant ovarian cancer cells. Gain-and-loss-of-function experiments assessed the impact on cisplatin sensitivity, both in vitro and in vivo. Fluorescence in situ hybridization was conducted to determine the cellular distribution of circRNAs, and RNA pulldown and immunoprecipitation experiments were performed to identify associated binding proteins.

RESULTS

The study revealed that circ_ARHGEF28 is overexpressed in certain cisplatin-resistant ovarian cancer tissues and cell lines, and is associated with reduced progression-free survival in patients. It was observed that circ_ARHGEF28 contributes to cisplatin resistance in ovarian cancer models, both in vitro and in vivo. Importantly, circ_ARHGEF28 was found to interact directly with MST1/2, inhibiting the SARAH coiled-coil binding domains and consequently deactivating the Hippo pathway.

CONCLUSION

This investigation identifies circ_ARHGEF28 as a novel circRNA that contributes to cisplatin resistance in ovarian cancer by suppressing the Hippo pathway. Therapeutic strategies targeting circ_ARHGEF28 may offer a potential avenue to mitigate cisplatin resistance in ovarian cancer treatment.

Generation of a biliary tract cancer cell line atlas reveals molecular subtypes and therapeutic targets

Biliary tract cancers (BTCs) are a group of deadly malignancies encompassing intrahepatic and extrahepatic cholangiocarcinoma, gallbladder carcinoma, and ampullary carcinoma. Here, we present the integrative analysis of 63 BTC cell lines via multi-omics clustering and genome- scale CRISPR screens, providing a platform to illuminate BTC biology and inform therapeutic development. We identify dependencies broadly enriched in BTC compared to other cancers as well as dependencies selective to the anatomic subtypes. Notably, cholangiocarcinoma cell lines are stratified into distinct lineage subtypes based on biliary or dual biliary/hepatocyte marker signatures, associated with dependency on specific lineage survival factors. Transcriptional analysis of patient specimens demonstrates the prognostic significance of these lineage subtypes. Additionally, we delineate strategies to enhance targeted therapies or to overcome resistance in cell lines with key driver gene mutations. Furthermore, clustering based on dependencies and proteomics data elucidates unexpected functional relationships, including a BTC subgroup with partial squamous differentiation. Thus, this cell line atlas reveals potential therapeutic targets in molecularly defined BTCs, unveils biologically distinct disease subtypes, and offers a vital resource for BTC research.

Crk mediates Csk-Hippo signaling independently of Yap tyrosine phosphorylation to induce cell extrusion

Src family kinases (SFKs), including Src, Fyn and Yes, play important roles in development and cancer. Despite being first discovered as the Yes-associated protein, the regulation of Yap by SFKs remains poorly understood. Here, through single-cell analysis and genetic lineage tracing, we show that the pan-epithelial ablation of C-terminal Src kinase (Csk) in the lacrimal gland unleashes broad Src signaling but specifically causes extrusion and apoptosis of acinar progenitors at a time when they are shielded by myoepithelial cells from the basement membrane. Csk mutants can be phenocopied by constitutively active Yap and rescued by deleting Yap or Taz, indicating a significant functional overlap between Src and Yap signaling. Although Src-induced tyrosine phosphorylation has long been believed to regulate Yap activity, we find that mutating these tyrosine residues in both Yap and Taz fails to perturb mouse development or alleviate the Csk lacrimal gland phenotype. In contrast, Yap loses Hippo signaling-dependent serine phosphorylation and translocates into the nucleus in Csk mutants. Further chemical genetics studies demonstrate that acute inhibition of Csk enhances Crk/CrkL phosphorylation and Rac1 activity, whereas removing Crk/CrkL or Rac1/Rap1 ameliorates the Csk mutant phenotype. These results show that Src controls Hippo-Yap signaling through the Crk/CrkL-Rac/Rap axis to promote cell extrusion.

The roles of Hippo/YAP signaling pathway in physical therapy

Cellular behavior is regulated by mechanical signals within the cellular microenvironment. Additionally, changes of temperature, blood flow, and muscle contraction also affect cellular state and the development of diseases. In clinical practice, physical therapy techniques such as ultrasound, vibration, exercise, cold therapy, and hyperthermia are commonly employed to alleviate pain and treat diseases. However, the molecular mechanism about how these physiotherapy methods stimulate local tissues and control gene expression remains unknow. Fortunately, the discovery of YAP filled this gap, which has been reported has the ability to sense and convert a wide variety of mechanical signals into cell-specific programs for transcription, thereby offering a fresh perspective on the mechanisms by which physiotherapy treat different diseases. This review examines the involvement of Hippo/YAP signaling pathway in various diseases and its role in different physical therapy approaches on diseases. Furthermore, we explore the potential therapeutic implications of the Hippo/YAP signaling pathway and address the limitations and controversies surrounding its application in physiotherapy.

YAP/TAZ-TEAD signalling axis: A new therapeutic target in malignant pleural mesothelioma

The Hippo signalling pathway, a highly conserved signalling cassette, regulates organ size by controlling cell growth, apoptosis and stem cell self-renewal. The tumourigenic potential of this pathway is largely attributed to the activity of YAP/TAZ, which activate the TEAD1-4 transcription factors, leading to the expression of genes involved in cell proliferation and suppression of cell death. Aberrant regulation of the YAP/TAZ-TEAD signalling axis is commonly observed in malignant pleural mesothelioma (MPM), an insidious neoplasm of the pleural tissue that lines the chest cavity and covers the lungs with poor prognosis. Given the limited effectiveness of current treatments, targeting the YAP/TAZ-TEAD signalling cascade has emerged as a promising therapeutic strategy in MPM. Several inhibitors of the YAP/TAZ-TEAD signalling axis are presently undergoing clinical development, with the goal of advancing them to clinical use in the near future.

Discovery of non-genomic drivers of YAP signaling modulating the cell plasticity in CRC tumor lines

In normal intestines, a fetal/regenerative/revival cell state can be induced upon inflammation. This plasticity in cell fate is also one of the current topics in human colorectal cancer (CRC). To dissect the underlying mechanisms, we generated human CRC organoids with naturally selected genetic mutation profiles and exposed them to two different conditions by modulating the extracellular matrix (ECM). Among tested mutation profiles, a fetal/regenerative/revival state was induced following YAP activation via a collagen type I-enriched microenvironment. Mechanistically, YAP transcription was promoted by activating AP-1 and TEAD-dependent transcription and suppressing intestinal lineage-determining transcription via mechanotransduction. The phenotypic conversion was also involved in chemoresistance, which could be potentially resolved by targeting the underlying YAP regulatory elements, a potential target of CRC treatment.

The Hippo-YAP Signaling Pathway in Osteoarthritis and Rheumatoid Arthritis

Arthritis is the most prevalent joint disease and is characterized by articular cartilage degradation, synovial inflammation, and changes in periarticular and subchondral bone. Recent studies have reported that Yes-associated protein (YAP) and the transcriptional coactivator with PDZ-binding motif (TAZ) have significant effects on the proliferation, migration, and survival of chondrocytes and fibroblast-like synovial cells (FLSs). YAP/TAZ signaling pathway, as well as the related Hippo-YAP signaling pathway, are responsible for the condition of cells and articular cartilage in joints. They are tightly regulated to maintain metabolism in chondrocytes and FLSs because abnormal expression may result in cartilage damage. However, the roles and mechanisms of the Hippo-YAP pathway in arthritis remain largely unknown. This review summarizes the roles and key functions of YAP/TAZ and the Hippo-YAP signaling pathway in FLSs and chondrocytes for the induction of proliferation, migration, survival, and differentiation in rheumatoid arthritis (RA) and osteoarthritis (OA) research. We also discuss the therapeutic strategies involving YAP/TAZ and the related Hippo-YAP signaling pathway involved in OA.

Oncoprotein SET-associated transcription factor ZBTB11 triggers lung cancer metastasis

Metastasis is the major cause of lung cancer-related death, but the mechanisms governing lung tumor metastasis remain incompletely elucidated. SE translocation (SET) is overexpressed in lung tumors and correlates with unfavorable prognosis. Here we uncover SET-associated transcription factor, zinc finger and BTB domain-containing protein 11 (ZBTB11), as a prometastatic regulator in lung tumors. SET interacts and collaborates with ZBTB11 to promote lung cancer cell migration and invasion, primarily through SET-ZBTB11 complex-mediated transcriptional activation of matrix metalloproteinase-9 (MMP9). Additionally, by transcriptional repression of proline-rich Gla protein 2 (PRRG2), ZBTB11 links Yes-associated protein 1 (YAP1) activation to drive lung tumor metastasis independently of SET-ZBTB11 complex. Loss of ZBTB11 suppresses distal metastasis in a lung tumor mouse model. Overexpression of ZBTB11 is recapitulated in human metastatic lung tumors and correlates with diminished survival. Our study demonstrates ZBTB11 as a key metastatic regulator and reveals diverse mechanisms by which ZBTB11 modulates lung tumor metastasis.

Distinct and overlapping functions of YAP and TAZ in tooth development and periodontal homeostasis

Orthodontic tooth movement (OTM) involves mechanical-biochemical signal transduction, which results in tissue remodeling of the tooth-periodontium complex and the movement of orthodontic teeth. The dynamic regulation of osteogenesis and osteoclastogenesis serves as the biological basis for remodeling of the periodontium, and more importantly, the prerequisite for establishing periodontal homeostasis. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are key effectors of the Hippo signaling pathway, which actively respond to mechanical stimuli during tooth movement. Specifically, they participate in translating mechanical into biochemical signals, thereby regulating periodontal homeostasis, periodontal remodeling, and tooth development. YAP and TAZ have widely been considered as key factors to prevent dental dysplasia, accelerate orthodontic tooth movement, and shorten treatment time. In this review, we summarize the functions of YAP and TAZ in regulating tooth development and periodontal remodeling, with the aim to gain a better understanding of their mechanisms of action and provide insights into maintaining proper tooth development and establishing a healthy periodontal and alveolar bone environment. Our findings offer novel perspectives and directions for targeted clinical treatments. Moreover, considering the similarities and differences in the development, structure, and physiology between YAP and TAZ, these molecules may exhibit functional variations in specific regulatory processes. Hence, we pay special attention to their distinct roles in specific regulatory functions to gain a comprehensive and profound understanding of their contributions.

Role of Hippo-YAP/TAZ signaling pathway in organ fibrosis

Organ fibrosis is closely associated with inflammation, tissue injury, and abnormal repair processes, characterized primarily by the activation of myofibroblasts and excessive extracellular matrix deposition. While the clinical manifestations and pathogenesis of fibrosis vary across organs, the progression of fibrosis can disrupt normal organ function, leading to disability or even death. The Hippo signaling pathway, an evolutionarily conserved kinase cascade, plays a pivotal role in regulating cell proliferation, apoptosis, differentiation, and tissue regeneration. Its primary effectors, yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are critically implicated in fibrosis of organs such as the kidney, liver, lung, heart, and skin. Currently, effective and specific treatments for organ fibrosis are lacking. A comprehensive understanding of the relationship between Hippo-YAP/TAZ signaling and organ fibrosis may provide novel perspectives for the clinical management of these conditions.

Does subtyping of high-grade pulmonary neuroendocrine carcinomas have an impact on therapy selection?

Background

Small cell lung cancer (SCLC) and large cell neuroendocrine carcinomas (LCNEC) are characterized by a rapid progressive course. Therapy for SCLC has not much changed for decades, and in LCNEC controversies exist, favoring either SCLC-like or non-small cell lung cancer (NSCLC)-like therapy. Three subtypes of SCLC identified in cell cultures, namely ASCL1, NeuroD1, and POU2F3 have been confirmed by immunohistochemistry. The fourth type based on the expression of YAP1 was questioned, and another type, inflamed SCLC, was proposed.

Methods

SCLC and LCNEC samples were investigated by immunohistochemistry for different subtypes. Additionally, immunohistochemical markers as potential tools to identify patients who might respond to targeted treatment were investigated. For validation a biopsy set was added.

Results

ASCL1, NeuroD1, and POU2F3 were expressed in different percentages in SCLC and LCNEC. Similar percentages of expression were found in biopsies. ATOH was expressed in combination with one of the subtypes. YAP1 and TAZ were expressed in some SCLC and LCNEC cases. HES1 expression was seen in few cases. Predominantly stroma cells expressed programmed cell death ligand 1 (PD-L1). The dominant MYC protein was N-MYC. Aurora kinase A (AURKA) was expressed in the majority of both carcinomas, whereas fibroblast growth factor receptor 2 (FGFR2) in few.

Conclusions

SCLC and LCNEC can be subtyped into ASCL1-, NeuroD1-, and POU2F3-positive types. AURKA expression and positivity for N-MYC protein was not associated with subtypes. AURKA and FGFR2 are both possible targets for inhibition in SCLC and LCNEC, but patients' selection should be based on expression of the enzyme. Combined chemo- and immunotherapy might be decided by PD-L1 staining of stroma cells.

New Insights into YAP/TAZ-TEAD-Mediated Gene Regulation and Biological Processes in Cancer

The Hippo pathway is conserved across species. Key mammalian Hippo pathway kinases, including MST1/2 and LATS1/2, inhibit cellular growth by inactivating the TEAD coactivators, YAP, and TAZ. Extensive research has illuminated the roles of Hippo signaling in cancer, development, and regeneration. Notably, dysregulation of Hippo pathway components not only contributes to tumor growth and metastasis, but also renders tumors resistant to therapies. This review delves into recent research on YAP/TAZ-TEAD-mediated gene regulation and biological processes in cancer. We focus on several key areas: newly identified molecular patterns of YAP/TAZ activation, emerging mechanisms that contribute to metastasis and cancer therapy resistance, unexpected roles in tumor suppression, and advances in therapeutic strategies targeting this pathway. Moreover, we provide an updated view of YAP/TAZ's biological functions, discuss ongoing controversies, and offer perspectives on specific debated topics in this rapidly evolving field.

Mechanobiological Strategies to Augment Cancer Treatment

Cancer cells exhibit aberrant extracellular matrix mechanosensing due to the altered expression of mechanosensory cytoskeletal proteins. Such aberrant mechanosensing of the tumor microenvironment (TME) by cancer cells is associated with disease development and progression. In addition, recent studies show that such mechanosensing changes the mechanobiological properties of cells, and in turn cells become susceptible to mechanical perturbations. Due to an increasing understanding of cell biomechanics and cellular machinery, several approaches have emerged to target the mechanobiological properties of cancer cells and cancer-associated cells to inhibit cancer growth and progression. In this Perspective, we summarize the progress in developing mechano-based approaches to target cancer by interfering with the cellular mechanosensing machinery and overall TME.

The HPV8 E6 protein targets the Hippo and Wnt signaling pathways as part of its arsenal to restrain keratinocyte differentiation

IMPORTANCE

Human papillomaviruses (HPVs) infect basal epithelial cells and cause a dramatic expansion of basal-like, proliferative cells. This reflects the ability of papillomaviruses to delay keratinocyte differentiation, thereby maintaining aspects of the basal cell identity of persistently infected cells. This may enable papillomaviruses to establish and maintain long-term infections in squamous epithelial tissues. Previous work has revealed that the ability of β-HPV8 E6 protein to inhibit Notch and transforming growth factor β signaling importantly contributes to this activity. Here, we present evidence that HPV8 E6 also subverts Hippo and Wnt signaling and that these activities also aid in restraining keratinocyte differentiation.

Collagen code in tumor microenvironment: Functions, molecular mechanisms, and therapeutic implications

The tumor microenvironment (TME) is crucial in cancer progression, and the extracellular matrix (ECM) is an important TME component. Collagen is a major ECM component that contributes to tumor cell infiltration, expansion, and distant metastasis during cancer progression. Recent studies reported that collagen is deposited in the TME to form a collagen wall along which tumor cells can infiltrate and prevent drugs from working on the tumor cells. Collagen-tumor cell interaction is complex and requires the activation of multiple signaling pathways for biochemical and mechanical signaling interventions. In this review, we examine the effect of collagen deposition in the TME on tumor progression and discuss the interaction between collagen and tumor cells. This review aims to illustrate the functions and mechanisms of collagen in tumor progression in the TME and its role in tumor therapy. The findings indicated collagen in the TME appears to be a better target for cancer therapy.

Ezrin promotes esophageal squamous cell carcinoma progression via the Hippo signaling pathway

The aim of this study was to analyze the role of Ezrin in esophageal squamous cell carcinoma (ESCC) and investigate potential therapeutic targets for ESCC by interfering with Ezrin expression. Bioinformatics analysis revealed that Ezrin expression differed significantly among patients with different clinical stage ESCC. Moreover, there was a significant correlation between Ezrin and yes-associated protein/connective tissue growth factor (YAP1/CTGF) levels in esophageal cancer. Sixty paraffin-embedded ESCC tissue samples were examined and Ezrin and YAP1/CTGF levels were determined using immunohistochemistry. The positive expression rates of Ezrin and YAP1/CTGF were significantly lower in adjacent tissues than in ESCC tissues. Furthermore, knockdown of Ezrin expression inhibited colony formation and reduced cell migration and invasion. Compared with control ESCC cells, protein expression levels of YAP1 and CTGF were significantly downregulated in cells with Ezrin knocked down. We conclude that Ezrin may be involved in ESCC progression through the Hippo signaling pathway.

The role of E3 ubiquitin ligases and deubiquitinases in bladder cancer development and immunotherapy

Bladder cancer is one of the common malignant urothelial tumors. Post-translational modification (PTMs), including ubiquitination, acetylation, methylation, and phosphorylation, have been revealed to participate in bladder cancer initiation and progression. Ubiquitination is the common PTM, which is conducted by E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme and E3 ubiquitin-protein ligase. E3 ubiquitin ligases play a key role in bladder oncogenesis and progression and drug resistance in bladder cancer. Therefore, in this review, we summarize current knowledge regarding the functions of E3 ubiquitin ligases in bladder cancer development. Moreover, we provide the evidence of E3 ubiquitin ligases in regulation of immunotherapy in bladder cancer. Furthermore, we mention the multiple compounds that target E3 ubiquitin ligases to improve the therapy efficacy of bladder cancer. We hope our review can stimulate researchers and clinicians to investigate whether and how targeting E3 ubiquitin ligases acts a novel strategy for bladder cancer therapy.