Targeting the Hippo Pathway and Cancer through the TEAD Family of Transcription Factors.
ABSTRACT: The Hippo pathway is a critical transcriptional signaling pathway that regulates cell growth, proliferation and organ development. The transcriptional enhanced associate domain (TEAD) protein family consists of four paralogous transcription factors that function to modulate gene expression in response to the Hippo signaling pathway. Transcriptional activation of these proteins occurs upon binding to the co-activator YAP/TAZ whose entry into the nucleus is regulated by Lats1/2 kinase. In recent years, it has become apparent that the dysregulation and/or overexpression of Hippo pathway effectors is implicated in a wide range of cancers, including prostate, gastric and liver cancer. A large body of work has been dedicated to understanding the therapeutic potential of modulating the phosphorylation and localization of YAP/TAZ. However, YAP/TAZ are considered to be natively unfolded and may be intractable as drug targets. Therefore, TEAD proteins present themselves as an excellent therapeutic target for intervention of the Hippo pathway. This review summarizes the functional role of TEAD proteins in cancer and assesses the therapeutic potential of antagonizing TEAD function in vivo.
Project description:Hippo signaling restricts tumor growth by inhibiting the oncogenic potential of YAP/TAZ-TEAD transcriptional complex. Here, we uncover a context-dependent tumor suppressor function of YAP in androgen receptor (AR) positive prostate cancer (PCa) and show that YAP impedes AR+ PCa growth by antagonizing TEAD-mediated AR signaling. TEAD forms a complex with AR to enhance its promoter/enhancer occupancy and transcriptional activity. YAP and AR compete for TEAD binding and consequently, elevated YAP in the nucleus disrupts AR-TEAD interaction and prevents TEAD from promoting AR signaling. Pharmacological inhibition of MST1/2 or LATS1/2, or transgenic activation of YAP suppressed the growth of PCa expressing therapy resistant AR splicing variants. Our study uncovers an unanticipated crosstalk between Hippo and AR signaling pathways, reveals an antagonistic relationship between YAP and TEAD in AR+ PCa, and suggests that targeting the Hippo signaling pathway may provide a therapeutical opportunity to treat PCa driven by therapy resistant AR variants.
Project description:The Hippo pathway controls organ size and tissue homeostasis, with deregulation leading to cancer. The core Hippo components in mammals are composed of the upstream serine/threonine kinases Mst1/2, MAPK4Ks and Lats1/2. Inactivation of these upstream kinases leads to dephosphorylation, stabilization, nuclear translocation and thus activation of the major functional transducers of the Hippo pathway, YAP and its paralogue TAZ. YAP/TAZ are transcription co-activators that regulate gene expression primarily through interaction with the TEA domain DNA-binding family of transcription factors (TEAD). The current paradigm for regulation of this pathway centres on phosphorylation-dependent nucleocytoplasmic shuttling of YAP/TAZ through a complex network of upstream components. However, unlike other transcription factors, such as SMAD, NF-?B, NFAT and STAT, the regulation of TEAD nucleocytoplasmic shuttling has been largely overlooked. In the present study, we show that environmental stress promotes TEAD cytoplasmic translocation via p38 MAPK in a Hippo-independent manner. Importantly, stress-induced TEAD inhibition predominates YAP-activating signals and selectively suppresses YAP-driven cancer cell growth. Our data reveal a mechanism governing TEAD nucleocytoplasmic shuttling and show that TEAD localization is a critical determinant of Hippo signalling output.
Project description:The Hippo pathway has emerged as a key signaling pathway that regulates a broad range of biological functions, and dysregulation of the Hippo pathway is a feature of a variety of cancers. Given this, some have suggested that disrupting the interaction of the Hippo core component YAP and its paralog TAZ with transcriptional factor TEAD may be an effective strategy for cancer therapy. However, there are currently no clinically available drugs targeting the YAP/TAZ-TEAD interaction for cancer treatment. To facilitate screens for small molecule compounds that disrupt the YAP-TEAD interaction, we have developed the first ultra-bright NanoLuc biosensor to quantify YAP/TAZ-TEAD protein-protein interaction (PPI) both in living cells and also in vitro using biosensor fusion proteins purified from bacteria. Using this biosensor, we have performed an in vitro high throughput screen (HTS) of small molecule compounds and have identified and validated the drug Celastrol as a novel inhibitor of YAP/TAZ-TEAD interaction. We have also demonstrated that Celastrol can inhibit cancer cell proliferation, transformation, and cell migration. In this study, we describe a new inhibitor of the YAP/TAZ-TEAD interaction warranting further investigation and offer a novel biosensor tool for the discovery of other new Hippo-targeting drugs in future work.
Project description:The Hippo pathway is a tumor suppressor pathway that is implicated in the regulation of organ size. The pathway has three components: the upstream regulatory factors, the kinase core, and the downstream transcriptional machinery, which consists of YAP, TAZ (transcription co-activators) and TEAD (transcription factor). Formation of YAP/TAZ-TEAD complexes leads to the transcription of growth-promoting genes. Herein, we report the crystal structure of TAZ-TEAD4 complex, which reveals two binding modes. The first is similar to the published YAP-TEAD structure. The second is a unique binding mode, whereby two molecules of TAZ bind to and bridge two molecules of TEAD4. We validated the latter using cross-linking and multi-angle light scattering. Using siRNA, we showed that TAZ knockdown leads to a decrease in TEAD4 dimerization. Lastly, results from luciferase assays, using YAP/TAZ transfected or knockdown cells, give support to the non-redundancy of YAP/TAZ co-activators in regulating gene expression in the Hippo pathway.
Project description:To investigate the role of Hippo pathway signaling during vertebrate development transgenic zebrafish lines were generated and validated to dynamically monitor and manipulate Yap/Taz-Tead activity. Spatial and temporal analysis of Yap/Taz-Tead activity suggested the importance of Hippo signaling during cardiac precursor migration and other developmental processes. When the transcriptional co-activators, Yap and Taz were restricted from interacting with DNA-binding Tead transcription factors through expression of a dominant negative transgene, cardiac precursors failed to migrate completely to the midline resulting in strong cardia bifida. Yap/Taz-Tead activity reporters also allowed us to investigate upstream and downstream factors known to regulate Hippo signaling output in Drosophila. While Crumbs mutations in Drosophila eye disc epithelia increase nuclear translocation and activity of Yorkie (the fly homolog of Yap/Taz), zebrafish crb2a mutants lacked nuclear Yap positive cells and down-regulated Yap/Taz-Tead activity reporters in the eye epithelia, despite the loss of apical-basal cell polarity in those cells. However, as an example of evolutionary conservation, the Tondu-domain containing protein Vestigial-like 4b (Vgll4b) was found to down-regulate endogenous Yap/Taz-Tead activity in the retinal pigment epithelium, similar to Drosophila Tgi in imaginal discs. In conclusion, the Yap/Taz-Tead activity reporters revealed the dynamics of Yap/Taz-Tead signaling and novel insights into Hippo pathway regulation for vertebrates. These studies highlight the utility of this transgenic tool-suite for ongoing analysis into the mechanisms of Hippo pathway regulation and the consequences of signaling output.
Project description:The Hippo pathway is a key signaling pathway in the control of organ size and development. The most distal elements of this pathway, the TEAD transcription factors, are regulated by several proteins, such as YAP (Yes-associated protein), TAZ (transcriptional co-activator with PDZ-binding motif) and VGLL1-4 (Vestigial-like members 1-4). In this article, combining structural data and motif searches in protein databases, we identify two new TEAD interactors: FAM181A and FAM181B. Our structural data show that they bind to TEAD via an ?-loop as YAP/TAZ do, but only FAM181B possesses the LxxLF motif (x any amino acid) found in YAP/TAZ. The affinity of different FAM181A/B fragments for TEAD is in the low micromolar range and full-length FAM181A/B proteins interact with TEAD in cells. These findings, together with a recent report showing that FAM181A/B proteins have a role in nervous system development, suggest a potential new involvement of the TEAD transcription factors in the development of this tissue.
Project description:YAP/TAZ are nuclear effectors of the Hippo pathway regulating organ growth and tumorigenesis. Yet, their function as transcriptional regulators remains underinvestigated. By ChIP-seq analyses in breast cancer cells, we discovered that the YAP/TAZ transcriptional response is pervasively mediated by a dual element: TEAD factors, through which YAP/TAZ bind to DNA, co-occupying chromatin with activator protein-1 (AP-1, dimer of JUN and FOS proteins) at composite cis-regulatory elements harbouring both TEAD and AP-1 motifs. YAP/TAZ/TEAD and AP-1 form a complex that synergistically activates target genes directly involved in the control of S-phase entry and mitosis. This control occurs almost exclusively from distal enhancers that contact target promoters through chromatin looping. YAP/TAZ-induced oncogenic growth is strongly enhanced by gain of AP-1 and severely blunted by its loss. Conversely, AP-1-promoted skin tumorigenesis is prevented in YAP/TAZ conditional knockout mice. This work highlights a new layer of signalling integration, feeding on YAP/TAZ function at the chromatin level.
Project description:The Hippo signaling pathway regulates cell fate and organ development. In the Hippo pathway, transcriptional enhanced associate domain (TEAD) which is a transcription factor is activated by forming a complex with yes-associated protein 1 (YAP1) or transcriptional coactivator with PDZ-binding motif (TAZ, also called WWTR1). Hyper-activation of YAP1/TAZ, leading to the activation of TEAD, has been reported in many cancers, including malignant pleural mesothelioma (MPM). Therefore, the YAP1/TAZ-TEAD complex is considered a novel therapeutic target for cancer treatment. However, few reports have described YAP1/TAZ-TEAD inhibitors, and their efficacy and selectivity are poor. In this study, we performed a high-throughput screening of a neurofibromin 2 (NF2)-deficient MPM cell line and a large tumor suppressor kinase 1/2 (LATS1/2)-deficient non-small-cell lung cancer cell line using a transcriptional reporter assay. After screening and optimization, K-975 was successfully identified as a potent inhibitor of YAP1/TAZ-TEAD signaling. X-ray crystallography revealed that K-975 was covalently bound to an internal cysteine residue located in the palmitate-binding pocket of TEAD. K-975 had a strong inhibitory effect against protein-protein interactions between YAP1/TAZ and TEAD in cell-free and cell-based assays. Furthermore, K-975 potently inhibited the proliferation of NF2-non-expressing MPM cell lines compared with NF2-expressing MPM cell lines. K-975 also suppressed tumor growth and provided significant survival benefit in MPM xenograft models. These findings indicate that K-975 is a strong and selective TEAD inhibitor with the potential to become an effective drug candidate for MPM therapy.
Project description:The Hippo signaling pathway, which is implicated in the regulation of organ size, has emerged as a potential target for the development of cancer therapeutics. YAP, TAZ (transcription co-activators) and TEAD (transcription factor) are the downstream transcriptional machinery and effectors of the pathway. Formation of the YAP/TAZ-TEAD complex leads to transcription of growth-promoting genes. Conversely, disrupting the interactions of the complex decreases cell proliferation. Herein, we screened a 1000-member fragment library using Thermal Shift Assay and identified a hit fragment. We confirmed its binding at the YAP/TAZ-TEAD interface by X-ray crystallography, and showed that it occupies the same hydrophobic pocket as a conserved phenylalanine of YAP/TAZ. This hit fragment serves as a scaffold for the development of compounds that have the potential to disrupt YAP/TAZ-TEAD interactions. Structure-activity relationship studies and computational modeling were also carried out to identify more potent compounds that may bind at this validated druggable binding site.
Project description:One of the hallmarks of cancers is the silencing of tumour suppressor genes and pathways. The Hippo tumour suppressor pathway is inactivated in many types of cancers, leading to tumour progression and metastasis. However, the mechanisms of pathway inactivation in tumours remain unclear. Here we demonstrate that integrin-linked kinase (ILK) plays a critical role in the suppression of the Hippo pathway via phospho-inhibition of MYPT1-PP1, leading to inactivation of Merlin. Inhibition of ILK in breast, prostate and colon tumour cells results in the activation of the Hippo pathway components MST1 and LATS1 with concomitant inactivation of YAP/TAZ (Yes-associated protein/transcriptional co-activator with PDZ-binding motif) transcriptional co-activators and TEAD-mediated transcription. Genetic deletion of ILK suppresses ErbB2-driven YAP/TAZ activation in mammary tumours, and its pharmacological inhibition suppresses YAP activation and tumour growth in vivo. Our data demonstrate a role for ILK as a multiple receptor proximal regulator of Hippo tumour suppressor pathway and as a cancer therapeutic target.