Regulation Of Hippo Signaling Research Articles

Tead4 and Tfap2c generate bipotency and a bistable switch in totipotent embryos to promote robust lineage diversification

The mouse and human embryo gradually loses totipotency before diversifying into the inner cell mass (ICM, future organism) and trophectoderm (TE, future placenta). The transcription factors TFAP2C and TEAD4 with activated RHOA accelerate embryo polarization. Here we show that these factors also accelerate the loss of totipotency. TFAP2C and TEAD4 paradoxically promote and inhibit Hippo signaling before lineage diversification: they drive expression of multiple Hippo regulators while also promoting apical domain formation, which inactivates Hippo. Each factor activates TE specifiers in bipotent cells, while TFAP2C also activates specifiers of the ICM fate. Asymmetric segregation of the apical domain reconciles the opposing regulation of Hippo signaling into Hippo OFF and the TE fate, or Hippo ON and the ICM fate. We propose that the bistable switch established by TFAP2C and TEAD4 is exploited to trigger robust lineage diversification in the developing embryo.

INHBA regulates Hippo signaling to confer 5-FU chemoresistance mediated by cellular senescence in colon cancer cells

Colon cancer has become a global public health challenge, and 5-Fluorouracil (5-FU) chemoresistance is a major obstacle in its treatment. Chemoresistance can be mediated by therapy-induced cellular senescence. This study intended to investigate mechanisms of INHBA (inhibin A) in 5-FU resistance mediated by cellular senescence in colon cancer. Bioinformatics analysis of INHBA expression in colon cancer tissues, survival analysis, and correlation analysis of cellular senescence markers were performed. The effects of INHBA on the biological characteristics and 5-FU resistance of colon cancer cells were examined through loss/gain-of-function and molecular assays. Finally, a xenograft mouse model was built to validate the mechanism of INHBA in vivo. INHBA was upregulated in colon cancer and was significantly positively correlated with cellular senescence markers uncoupling protein 2 (UCP-2), matrix metalloproteinase-1 (MMP-1), dense and erect panicle 1 (DEP1), and p21. Cellular senescence in colon cancer mediated 5-FU resistance. Downregulation of INHBA expression enhanced 5-FU sensitivity in colon cancer cells, inhibited cell proliferation, promoted apoptosis, increased the proportion of cells in G0/G1 phase, and it resulted in a lower proportion of senescent cells and lower levels of the cellular senescence markers interleukin 6 (IL-6) and interleukin 8 (IL-8). Analysis of whether to use the pathway inhibitor Verteporfin proved that INHBA facilitated colon cancer cell senescence and enhanced 5-FU chemoresistance via inactivation of Hippo signaling pathway, and consistent results were obtained in vivo. Collectively, INHBA conferred 5-FU chemoresistance mediated by cellular senescence in colon cancer cells through negative regulation of Hippo signaling.

Interplay of RAP2 GTPase and the cytoskeleton in Hippo pathway regulation

The Hippo signaling is instrumental in regulating organ size, regeneration, and carcinogenesis. The cytoskeleton emerges as a primary Hippo signaling modulator. Its structural alterations in response to environmental and intrinsic stimuli control Hippo signaling pathway activity. However, the precise mechanisms underlying the cytoskeleton regulation of Hippo signaling are not fully understood. RAP2 GTPase is known to mediate the mechanoresponses of Hippo signaling via activating the core Hippo kinases LATS1/2 through MAP4Ks and MST1/2. Here we show the pivotal role of the reciprocal regulation between RAP2 GTPase and the cytoskeleton in Hippo signaling. RAP2 deletion undermines the responses of the Hippo pathway to external cues tied to RhoA GTPase inhibition and actin cytoskeleton remodeling, such as energy stress and serum deprivation. Notably, RhoA inhibitors and actin disruptors fail to activate LATS1/2 effectively in RAP2-deficient cells. RNA sequencing highlighted differential regulation of both actin and microtubule networks by RAP2 gene deletion. Consistently, Taxol, a microtubule-stabilizing agent, was less effective in activating LATS1/2 and inhibiting cell growth in RAP2 and MAP4K4/6/7 knockout cells. In summary, our findings position RAP2 as a central integrator of cytoskeletal signals for Hippo signaling, which offers new avenues for understanding Hippo regulation and therapeutic interventions in Hippo-impaired cancers.

M6A-induced TRIB3 regulates Hippo pathway through interacting with LATS1 to promote the progression of lung adenocarcinoma.

Recent studies have indicated that dysregulation of the Hippo/Yes-associated protein (YAP) axis is associated with tumor progression and therapy resistance in various cancer types, including lung adenocarcinoma (LUAD). Understanding the regulation of Hippo signaling in LUAD is of great significance. Elevated levels of TRIB3, a pseudo kinase, have been observed in certain lung malignancies and are associated with an unfavorable prognosis. Our research aims to investigate whether increased TRIB3 levels enhance the malignant characteristics of LUAD cells and tumor progression through its interaction with the Hippo signaling pathway. In this study, we reported a positive correlation between elevated expression of TRIB3 and LUAD progression. Additionally, TRIB3 has the ability to enhance TEAD luciferase function and suppress Hippo pathway activity. Moreover, TRIB3 increases total YAP protein levels and promotes YAP nuclear localization. Mechanistic experiments revealed that TRIB3 directly interacts with large tumor suppressor kinase 1(LATS1), thereby suppressing Hippo signaling. Moreover, the decrease in METTL3-mediated N6-methyladenosine modification of TRIB3 results in a substantial elevation of its expression levels in LUAD cells. Collectively, our research unveils a novel discovery that TRIB3 enhances the growth and invasion of LUAD cells by interacting with LATS1 and inhibiting the Hippo signaling pathway. TRIB3 may serve as a potential biomarker for an unfavorable prognosis and a target for novel treatments in YAP-driven lung cancer.

Cyclic Phytosphingosine-1-Phosphate Primed Mesenchymal Stem Cells Ameliorate LPS-Induced Acute Lung Injury in Mice.

O-cyclic phytosphingosine-1-phosphate (cP1P) is a synthetic chemical and has a structure like sphingosine-1-phosphate (S1P). S1P is known to promote cell migration, invasion, proliferation, and anti-apoptosis through hippocampal signals. However, S1P mediated cellular-, molecular mechanism is still remained in the lung. Acute lung injury (ALI) and its severe form acute respiratory distress syndrome (ARDS) are characterized by excessive immune response, increased vascular permeability, alveolar-peritoneal barrier collapse, and edema. In this study, we determined whether cP1P primed human dermal derived mesenchymal stem cells (hdMSCs) ameliorate lung injury and its therapeutic pathway in ALI mice. cP1P treatment significantly stimulated MSC migration and invasion ability. In cytokine array, secretion of vascular-related factors was increased in cP1P primed hdMSCs (hdMSCcP1P), and cP1P treatment induced inhibition of Lats while increased phosphorylation of Yap. We next determined whether hdMSCcP1P reduce inflammatory response in LPS exposed mice. hdMSCcP1P further decreased infiltration of macrophage and neutrophil, and release of TNF-α, IL-1β, and IL-6 were reduced rather than naïve hdMSC treatment. In addition, phosphorylation of STAT1 and expression of iNOS were significantly decreased in the lungs of MSCcP1P treated mice. Taken together, these data suggest that cP1P treatment enhances hdMSC migration in regulation of Hippo signaling and MSCcP1P provide a therapeutic potential for ALI/ARDS treatment.

Analysis of the Drosophila Ajuba LIM protein defines functions for distinct LIM domains.

The Ajuba LIM protein Jub mediates regulation of Hippo signaling by cytoskeletal tension through interaction with the kinase Warts and participates in feedback regulation of junctional tension through regulation of the cytohesin Steppke. To investigate how Jub interacts with and regulates its distinct partners, we investigated the ability of Jub proteins missing different combinations of its three LIM domains to rescue jub phenotypes and to interact with α-catenin, Warts and Steppke. Multiple regions of Jub contribute to its ability to bind α-catenin and to localize to adherens junctions in Drosophila wing imaginal discs. Co-immunoprecipitation experiments in cultured cells identified a specific requirement for LIM2 for binding to Warts. However, in vivo, both LIM1 and LIM2, but not LIM3, were required for regulation of wing growth, Yorkie activity, and Warts localization. Conversely, LIM2 and LIM3, but not LIM1, were required for regulation of cell shape and Steppke localization in vivo, and for maximal Steppke binding in co-immunoprecipitation experiments. These observations identify distinct functions for the different LIM domains of Jub.

The unfolding of the Hippo signaling pathway

The development of a functional organ requires not only patterning mechanisms that confer proper identities to individual cells, but also growth-regulatory mechanisms that specify the final size of the organ. At the turn of the 21st century, comprehensive genetic screens in model organisms had successfully uncovered the major signaling pathways that mediate pattern formation in metazoans. In contrast, signaling pathways dedicated to growth control were less explored. The past two decades has witnessed the emergence of the Hippo signaling pathway as a central mediator of organ size control through coordinated regulation of cell proliferation and apoptosis. Here I reflect on the early discoveries in Drosophila that elucidated the core kinase cascade and transcriptional machinery of the Hippo pathway, highlight its deep evolutionary conservation from humans to unicellular relatives of metazoan, and discuss the complex regulation of Hippo signaling by upstream inputs. This historical perspective underscores the importance of model organisms in uncovering fundamental and universal mechanisms of life processes.

Regulation of Hippo signaling by metabolic pathways in cancer.

Hippo signaling is known to maintain balance between cell proliferation and apoptosis via tight regulation of factors, such as metabolic cues, cell-cell contact, and mechanical cues. Cells directly recognize glucose, lipids, and other metabolic cues and integrate multiple signaling pathways, including Hippo signaling, to adjust their proliferation and apoptosis depending on nutrient conditions. Therefore, the dysregulation of the Hippo signaling pathway can promote tumor initiation and progression. Alteration in metabolic cues is considered a major factor affecting the risk of cancer formation and progression. It has recently been shown that the dysregulation of the Hippo signaling pathway, through diverse routes activated by metabolic cues, can lead to cancer with a poor prognosis. In addition, unique crosstalk between metabolic pathways and Hippo signaling pathways can inhibit the effect of anticancer drugs and promote drug resistance. In this review, we describe an integrated perspective of the relationship between the Hippo signaling pathway and metabolic signals in the context of cancer. We also characterize the mechanisms involved in changes in metabolism that are linked to the Hippo signaling pathway in the cancer microenvironment and propose several novel targets for anticancer drug treatment.

Long Noncoding RNA LOC554202 Predicts a Poor Prognosis and Correlates with Immune Infiltration in Thyroid Cancer.

Thyroid cancer (TC) is one of the widely diagnosed carcinomas in women before the age of 30. Nevertheless, there is currently a lack of specific biomarkers for predicting the prognosis of TC. Long noncoding RNAs (lncRNAs) were important regulators in human cancer progression as previously described. Unfortunately, there is little known on these lncRNAs' functions and molecular mechanisms in TC. In our literature, we found that LOC554202 (MIR31HG) was upregulated in TC samples and correlated with clinicopathological features, including M stage, N stage, and lymph nodes examined status in TC. In addition, we found that LOC554202 overexpression was evidently correlated with high immune infiltrate levels of CD8+ T cells, macrophage, neutrophil, myeloid dendritic cells, and B cells in TC. Knockdown of LOC554202 impeded TC cell proliferation and cycle progression. We found that LOC554202 had an association with metabolic pathways, vesicle-mediated transport, tricarboxylic acid cycle, Hedgehog signaling pathway, and Hippo signaling pathway in TC. Reducing LOC554202 hindered TC cell proliferation and cycle progression. Finally, we found that LOC554202 participated in modulating the expression of the regulators of Hippo signaling and TCA pathway, such as CCND2, CCND3, SDHC, SDHD, SUCLA2, and SUCLG1. We thought that this study would largely enhance our understanding of LOC554202's functional roles in human TC progression and immune response.

Cell adhesion molecule KIRREL1 is a feedback regulator of Hippo signaling recruiting SAV1 to cell-cell contact sites

The Hippo/YAP pathway controls cell proliferation through sensing physical and spatial organization of cells. How cell-cell contact is sensed by Hippo signaling is poorly understood. Here, we identified the cell adhesion molecule KIRREL1 as an upstream positive regulator of the mammalian Hippo pathway. KIRREL1 physically interacts with SAV1 and recruits SAV1 to cell-cell contact sites. Consistent with the hypothesis that KIRREL1-mediated cell adhesion suppresses YAP activity, knockout of KIRREL1 increases YAP activity in neighboring cells. Analyzing pan-cancer CRISPR proliferation screen data reveals KIRREL1 as the top plasma membrane protein showing strong correlation with known Hippo regulators, highlighting a critical role of KIRREL1 in regulating Hippo signaling and cell proliferation. During liver regeneration in mice, KIRREL1 is upregulated, and its genetic ablation enhances hepatic YAP activity, hepatocyte reprogramming and biliary epithelial cell proliferation. Our data suggest that KIRREL1 functions as a feedback regulator of the mammalian Hippo pathway through sensing cell-cell interaction and recruiting SAV1 to cell-cell contact sites.

Modulation of Hippo signaling by Mnat9 N-acetyltransferase for normal growth and tumorigenesis in Drosophila

Hippo signaling is a conserved mechanism for controlling organ growth. Increasing evidence suggests that Hippo signaling is modulated by various cellular factors for normal development and tumorigenesis. Hence, identification of these factors is pivotal for understanding the mechanism for the regulation of Hippo signaling. Drosophila Mnat9 is a putative N-acetyltransferase that is required for cell survival by affecting JNK signaling. Here we show that Mnat9 is involved in the negative regulation of Hippo signaling. RNAi knockdown of Mnat9 in the eye disc suppresses the rough eye phenotype of overexpressing Crumbs (Crb), an upstream factor of the Hippo pathway. Conversely, Mnat9 RNAi enhances the eye phenotype caused by overexpressing Expanded (Ex) or Warts (Wts) that acts downstream to Crb. Similar genetic interactions between Mnat9 and Hippo pathway genes are found in the wing. The reduced wing phenotype of Mnat9 RNAi is suppressed by overexpression of Yorkie (Yki), while it is suppressed by knockdown of Hippo upstream factors like Ex, Merlin, or Kibra. Mnat9 co-immunoprecipitates with Mer, implying their function in a protein complex. Furthermore, Mnat9 overexpression together with Hpo knockdown causes tumorous overgrowth in the abdomen. Our data suggest that Mnat9 is required for organ growth and can induce tumorous growth by negatively regulating the Hippo signaling pathway.

Monitoring Hippo Signaling Pathway Activity Using a Luciferase-Based Large Tumor Suppressor (LATS) Biosensor.

Kinase cascades are a fundamental feature of cellular signaling and play a vital role in disease progression. Thus, tools to monitor the activity of kinase cascades are of high importance. Our group has developed asplit-luciferase biosensor system to monitor the activity of the Hippo pathway, a kinase cascade that regulates a wide variety of cellular processes. We have applied this biosensor for high-throughput screening to discover novel upstream kinase regulators of Hippo signaling. In this chapter, we describe our approach to designing, validating, and using the biosensor for screening procedures, which provides an example for the reader should they wish to design a similar biosensor system for their own purposes.

Willin/FRMD6: A Multi-Functional Neuronal Protein Associated with Alzheimer's Disease.

The FERM domain-containing protein 6 (FRMD6), also known as Willin, is an upstream regulator of Hippo signaling that has recently been shown to modulate actin cytoskeleton dynamics and mechanical phenotype of neuronal cells through ERK signaling. Physiological functions of Willin/FRMD6 in the nervous system include neuronal differentiation, myelination, nerve injury repair, and vesicle exocytosis. The newly established neuronal role of Willin/FRMD6 is of particular interest given the mounting evidence suggesting a role for Willin/FRMD6 in Alzheimer’s disease (AD), including a series of genome wide association studies that position Willin/FRMD6 as a novel AD risk gene. Here we describe recent findings regarding the role of Willin/FRMD6 in the nervous system and its actions in cellular perturbations related to the pathogenesis of AD.

Cytoskeleton-associated protein 4 (CKAP4) promotes malignant progression of human gliomas through inhibition of the Hippo signaling pathway.

Gliomas are the most common and aggressive malignant brain tumors and are associated with high mortality and incidence in humans. Despite rigorous multi-modal therapy, including surgery, chemotherapy and radiotherapy, patients with malignant glioma survive an average of 12-15months following primary diagnosis. Therefore, new molecular biomarkers are urgently needed for diagnosis and targeted therapy. Here, we find that suppression of CKAP4 might inhibit glioma growth through regulation of Hippo signaling. We examined the expression levels of CKAP4 through analysis of RNA sequencing data from GEPIA and CGGA databases. Then, Lentivirus was used toconstruct stable cell lines with knockout or overexpression of CKAP4. Next, the function of CKAP4 on glioma was investigated in vitro and in an orthotopic brain tumor model in mice. Lastly, luciferase reporter assay, immunofluorescence and immunoblotting were performed to explore the potential mechanism of how CKAP4 affects gliomas. CKAP4 is highly upregulated in glioma and high CKAP4 expressing tumors were associated with poor patient survival. And CKAP4 promotes malignant progression of gliomas via inhibiting Hippo signaling. CKAP4 has potential as a promising biomarker and can predict the prognosis of patients with gliomas. And targeting CKAP4 expression may be an effective therapeutic strategy for the treatment of human gliomas.

Mutations and Copy Number Abnormalities of Hippo Pathway Components in Human Cancers

The Hippo pathway is highly conserved from Drosophila to mammals. As a key regulator of cell proliferation, the Hippo pathway controls tissue homeostasis and has a major impact on tumorigenesis. The originally defined core components of the Hippo pathway in mammals include STK3/4, LATS1/2, YAP1/TAZ, TEAD, VGLL4, and NF2. However, for most of these genes, mutations and copy number variations are relatively uncommon in human cancer. Several other recently identified upstream and downstream regulators of Hippo signaling, including FAT1, SHANK2, Gq/11, and SWI/SNF complex, are more commonly dysregulated in human cancer at the genomic level. This review will discuss major genomic events in human cancer that enable cancer cells to escape the tumor-suppressive effects of Hippo signaling.

Copy number aberrations drive kinase rewiring, leading to genetic vulnerabilities in cancer.

SummarySomatic DNA copy number variations (CNVs) are prevalent in cancer and can drive cancer progression, albeit with often uncharacterized roles in altering cell signaling states. Here, we integrate genomic and proteomic data for 5,598 tumor samples to identify CNVs leading to aberrant signal transduction. The resulting associations recapitulate known kinase-substrate relationships, and further network analysis prioritizes likely causal genes. Of the 303 significant associations we identify from the pan-tumor analysis, 43% are replicated in cancer cell lines, including 44 robust gene-phosphosite associations identified across multiple tumor types. Several predicted regulators of hippo signaling are experimentally validated. Using RNAi, CRISPR, and drug screening data, we find evidence of kinase addiction in cancer cell lines, identifying inhibitors for targeting of kinase-dependent cell lines. We propose copy number status of genes as a useful predictor of differential impact of kinase inhibition, a strategy that may be of use in the future for anticancer therapies.

SKI activates the Hippo pathway via LIMD1 to inhibit cardiac fibroblast activation

We have previously shown that overexpression of SKI, an endogenous TGF-β1 repressor, deactivates the pro-fibrotic myofibroblast phenotype in the heart. We now show that SKI also functions independently of SMAD/TGF-β signaling, by activating the Hippo tumor-suppressor pathway and inhibiting the Transcriptional co-Activator with PDZ-binding motif (TAZ or WWTR1). The mechanism(s) by which SKI targets TAZ to inhibit cardiac fibroblast activation and fibrogenesis remain undefined. A rat model of post-myocardial infarction was used to examine the expression of TAZ during acute fibrogenesis and chronic heart failure. Results were then corroborated with primary rat cardiac fibroblast cell culture performed both on plastic and on inert elastic substrates, along with the use of siRNA and adenoviral expression vectors for active forms of SKI, YAP, and TAZ. Gene expression was examined by qPCR and luciferase assays, while protein expression was examined by immunoblotting and fluorescence microscopy. Cell phenotype was further assessed by functional assays. Finally, to elucidate SKI’s effects on Hippo signaling, the SKI and TAZ interactomes were captured in human cardiac fibroblasts using BioID2 and mass spectrometry. Potential interactors were investigated in vitro to reveal novel mechanisms of action for SKI. In vitro assays on elastic substrates revealed the ability of TAZ to overcome environmental stimuli and induce the activation of hypersynthetic cardiac myofibroblasts. Further cell-based assays demonstrated that SKI causes specific proteasomal degradation of TAZ, but not YAP, and shifts actin cytoskeleton dynamics to inhibit myofibroblast activation. These findings were supported by identifying the bi-phasic expression of TAZ in vivo during post-MI remodeling and fibrosis. BioID2-based interactomics in human cardiac fibroblasts suggest that SKI interacts with actin-modifying proteins and with LIM Domain-containing protein 1 (LIMD1), a negative regulator of Hippo signaling. Furthermore, we found that LATS2 interacts with TAZ, whereas LATS1 does not, and that LATS2 knockdown prevented TAZ downregulation with SKI overexpression. Our findings indicate that SKI’s capacity to regulate cardiac fibroblast activation is mediated, in part, by Hippo signaling. We postulate that the interaction between SKI and TAZ in cardiac fibroblasts is arbitrated by LIMD1, an important intermediary in focal adhesion-associated signaling pathways. This study contributes to the understanding of the unique physiology of cardiac fibroblasts, and of the relationship between SKI expression and cell phenotype.

Coordinated regulation of miR-27 by insulin/CREB/Hippo contributes to insulin resistance

MicroRNA-27 is a critical non-coding metabolic gene that is often aberrantly overexpressed in non-alcoholic fatty livers (NAFLD). However, the pathogenic role of miR-27 in NAFLD remains unknown. In this study, we attempted to identify the mechanism by which miR-27 was regulated in the context of insulin resistance, a predisposed metabolic disorder in NAFLD. Our data from cell culture and animal studies showed that insulin, CREB, and Hippo signalings coordinately regulated miR-27. First, miR-27 was upregulated in palmitate-treated cells and high fat diet-fed mouse livers, which exhibited insulin resistance and CREB overexpression. Second, miR-27 peaked in the mouse liver at the post-absorptive phase when CREB activity was increased. Also, miR-27 was increased rapidly in cell lines when CREB was deactivated by insulin treatment. Third, miR-27 was decreased in cultured cells when CREB was downregulated by siRNA or metformin treatment. In contrast, Forskolin-mediated activation of CREB promoted miR-27 expression. Fourth, Hippo signaling repressed miR-27 in a CREB-independent manner: miR-27 was reduced in cells at full confluence but was inhibited in cells transfected with siRNA against Lats2 and Nf2, which were two positive regulators of Hippo signaling. Lastly, bioinformatics and luciferase assay showed that miR-27 inhibited Akt phosphorylation by targeting Pdpk1 and Pik3r1. Overexpression of miR-27 impaired Akt phosphorylation in cell lines and primary mouse hepatocytes upon insulin stimulation. In conclusion, our data suggest that insulin, CREB, and Hippo signalings contribute to aberrant miR-27 overexpression and eventually lead to insulin resistance in NAFLD.

WWC Proteins: Important Regulators of Hippo Signaling in Cancer.

Simple SummaryThe conserved Hippo pathway regulates cell proliferation and apoptosis via a complex interplay of transcriptional activities, post-translational protein modifications, specific protein–protein interactions and cellular transport processes. Deregulating this highly balanced system can lead to hyperproliferation, organ overgrowth and cancer. Although WWC proteins are known as components of the Hippo signaling pathway, their association with tumorigenesis is often neglected. This review aims to summarize the current knowledge on WWC proteins and their contribution to Hippo signaling in the context of cancer.The Hippo signaling pathway is known to regulate cell differentiation, proliferation and apoptosis. Whereas activation of the Hippo signaling pathway leads to phosphorylation and cytoplasmic retention of the transcriptional coactivator YAP, decreased Hippo signaling results in nuclear import of YAP and subsequent transcription of pro-proliferative genes. Hence, a dynamic and precise regulation of the Hippo signaling pathway is crucial for organ size control and the prevention of tumor formation. The transcriptional activity of YAP is controlled by a growing number of upstream regulators including the family of WWC proteins. WWC1, WWC2 and WWC3 represent cytosolic scaffolding proteins involved in intracellular transport processes and different signal transduction pathways. Earlier in vitro experiments demonstrated that WWC proteins positively regulate the Hippo pathway via the activation of large tumor suppressor kinases 1/2 (LATS1/2) kinases and the subsequent cytoplasmic accumulation of phosphorylated YAP. Later, reduced WWC expression and subsequent high YAP activity were shown to correlate with the progression of human cancer in different organs. Although the function of WWC proteins as upstream regulators of Hippo signaling was confirmed in various studies, their important role as tumor modulators is often overlooked. This review has been designed to provide an update on the published data linking WWC1, WWC2 and WWC3 to cancer, with a focus on Hippo pathway-dependent mechanisms.

RACO-1 modulates Hippo signalling in oesophageal squamous cell carcinoma.

Oesophageal cancer is one of the most lethal malignancies worldwide, whereas the 5‐year survival is less than 20%. Although the detailed carcinogenic mechanisms are not totally clear, recent genomic sequencing data showed dysregulation of Hippo signalling could be a critical factor for oesophageal squamous cell carcinoma (ESCC) progression. Therefore, understanding of the molecular mechanisms that control Hippo signalling activity is of great importance to improve ESCC diagnostics and therapeutics. Our current study revealed RACO‐1 as an inhibitory protein for YAP/TEAD axis. Depletion of RACO‐1 increases the protein level of YAP and expression of YAP/TEAD target gene. Besides, RACO‐1 silencing could promote ESCC cell invasion and migration, which effect could be rescued by YAP depletion in ESCC cells. Immunoprecipitation showed that RACO‐1 associated with YAP and promote ubiquitination and degradation of YAP at k48 poly‐ubiquitination site. Our research discovered a new regulator of Hippo signalling via modulating YAP stability. RACO‐1 could be a promising factor, which serves cancer diagnostics and therapeutics in ESCC patients.