Safety Considerations in the Development of Hippo Pathway Inhibitors in Cancers

Activation of Hepatocyte Growth Factor/MET Signaling as a Mechanism of Acquired Resistance to a Novel YAP1/TEAD Small Molecule Inhibitor

Many tumor types harbor alterations in the Hippo pathway, including mesothelioma, where a high percentage of cases are considered YAP1/TEAD dependent. Identification of autopalmitoylation sites in the hydrophobic palmitate pocket of TEADs, which may be necessary for YAP1 protein interactions, has enabled modern drug discovery platforms to generate compounds that allosterically inhibit YAP1/TEAD complex formation and transcriptional activity. We report the discovery and characterization of a novel YAP1/TEAD inhibitor MRK-A from an aryl ether chemical series demonstrating potent and specific inhibition of YAP1/TEAD activity. In vivo, MRK-A showed a favorable tolerability profile in mice and demonstrated pharmacokinetics suitable for twice daily oral dosing in preclinical efficacy studies. Importantly, monotherapeutic targeting of YAP1/TEAD in preclinical models generated regressions in a mesothelioma CDX model; however, rapid resistance to therapy was observed. RNA-sequencing of resistant tumors revealed mRNA expression changes correlated with the resistance state and a marked increase of hepatocyte growth factor (HGF) expression. In vitro, exogenous HGF was able to fully rescue cytostasis induced by MRK-A in mesothelioma cell lines. In addition, co-administration of small molecule inhibitors of the MET receptor tyrosine kinase suppressed the resistance generating effect of HGF on MRK-A induced growth inhibition. In this work, we report the structure and characterization of MRK-A, demonstrating potent and specific inhibition of YAP1/TAZ-TEAD-mediated transcriptional responses, with potential implications for treating malignancies driven by altered Hippo signaling, including factors resulting in acquired drug resistance.

Direct Inhibition of the YAP : TEAD Interaction: An Unprecedented Drug Discovery Challenge

The Hippo pathway, which is key in organ morphogenesis, is frequently deregulated in cancer. The TEAD (TEA domain family member) transcription factors are the most distal elements of this pathway, and their activity is regulated by proteins such as YAP (Yes-associated protein). The identification of inhibitors of the YAP : TEAD interaction is one approach to develop novel anticancer drugs: the first clinical candidate (IAG933) preventing the association between these two proteins by direct competition has just been reported. The discovery of this molecule was particularly challenging because the interface between these two proteins is large (~3500 Å2 buried in complex formation) and made up of distinct contact areas. The most critical of these involves an omega-loop (Ω-loop), a secondary structure element rarely found in protein-protein interactions. This review summarizes how the knowledge gained from structure-function studies of the interaction between the Ω-loop of YAP and TEAD was used to devise the strategy to identify potent low-molecular weight compounds that show a pronounced anti-tumor effect.

Placental co-transcriptional activator Vestigial-like 1 (VGLL1) drives tumorigenesis via increasing transcription of proliferation and invasion genes

Introduction

Vestigial-like 1 (VGLL1) is a co-transcriptional activator that binds to TEA domain-containing transcription factors (TEADs). Its expression is upregulated in a variety of aggressive cancer types, including pancreatic and basal-like breast cancer, and increased transcription of VGLL1 is strongly correlated with poor prognosis and decreased overall patient survival. In normal tissues, VGLL1 is most highly expressed within placental trophoblast cells, which share the common attributes of rapid cellular proliferation and invasion with tumor cells. The impact of VGLL1 in cancer has not been fully elucidated and no VGLL1-targeted therapy currently exists.

Methods

The aim of this study was to evaluate the cellular function and downstream genomic targets of VGLL1 in placental, pancreatic, and breast cancer cells. Functional assays were employed to assess the role of VGLL1 in cellular invasion and proliferation, and ChIP-seq and RNAseq assays were performed to identify VGLL1 target genes and potential impact using pathway analysis.

Results

ChIP-seq analysis identified eight transcription factors with a VGLL1-binding motif that were common between all three cell types, including TEAD1-4, AP-1, and GATA6, and revealed ~3,000 shared genes with which VGLL1 interacts. Furthermore, increased VGLL1 expression led to an enhancement of cell invasion and proliferation, which was supported by RNAseq analysis showing transcriptional changes in several genes known to be involved in these processes.

Discussion

This work expands our mechanistic understanding of VGLL1 function in tumor cells and provides a strong rationale for developing VGLL1-targeted therapies for treating cancer patients.

YAP targetome reveals activation of SPEM in gastric pre-neoplastic progression and regeneration

Peptic ulcer disease caused by environmental factors increases the risk of developing gastric cancer (GC), one of the most common and deadly cancers in the world. However, the mechanisms underlying this association remain unclear. A major type of GC uniquely undergoes spasmolytic polypeptide-expressing metaplasia (SPEM) followed by intestinal metaplasia. Notably, intestinal-type GC patients with high levels of YAP signaling exhibit a lower survival rate and poor prognosis. YAP overexpression in gastric cells induces atrophy, metaplasia, and hyperproliferation, while its deletion in a Notch-activated gastric adenoma model suppresses them. By defining the YAP targetome genome-wide, we demonstrate that YAP binds to active chromatin elements of SPEM-related genes, which correlates with the activation of their expression in both metaplasia and ulcers. Single-cell analysis combined with our YAP signature reveals that YAP signaling is activated during SPEM, demonstrating YAP as a central regulator of SPEM in gastric neoplasia and regeneration.

Complex roles of Hippo-YAP/TAZ signaling in hepatocellular carcinoma

BACKGROUND

The Hippo signaling pathway is an evolutionarily conserved signaling module that controls organ size in different species, and the disorder of the Hippo pathway can induce liver cancer in organisms, especially hepatocellular carcinoma (HCC). The exact mechanism that causes cancer is still unknown. Recent studies have shown that it is a classical kinase cascade that phosphorylates the Mst1/2-sav1 complex and activates the phosphorylation of the Lats1/2-mob1A/B complex for inactivating Yap and Taz. These kinases and scaffolds are regarded as primary regulators of the Hippo pathway, and help in activating a variety of carcinogenic processes. Among them, Yap/Taz is seen to be the main effector molecule, which is downstream of the Hippo pathway, and its abnormal activation is related to a variety of human cancers including liver cancer. Currently, since Yap/Taz plays a variety of roles in cancer promotion and tumor regeneration, the Hippo pathway has emerged as an attractive target in recent drug development research.

METHODS

We collect and review relevant literature in web of Science and Pubmed.

CONCLUSION

This review highlights the important roles of Yap/Taz in activating Hippo pathway in liver cancer. The recent findings on the crosstalks between the Hippo and other cancer associated pathways and moleculars are also discussed. In this review, we summarized and discussed recent breakthroughs in our understanding of how key components of the Hippo-YAP/TAZ pathway influence the hepatocellular carcinoma, including their effects on tumor occurrence and development, their roles in regulating metastasis, and their function in chemotherapy resistance. Further, the molecular mechanism and roles in regulating cross talk between Hippo-YAP/TAZ pathway and other cancer-associated pathways or oncogenes/cancer suppressor genes were summarized and discussed. More, many other inducers and inhibitors of this signaling cascade and available experimental therapies against the YAP/TAZ/TEAD axis were discussed. Targeting this pathway for cancer therapy may have great significance in the treatment of hepatocellular carcinoma. Graphical summary of the complex role of Hippo-YAP/TAZ signaling in hepatocellular carcinoma.

Recent advances in the understanding of urothelial tumorigenesis

INTRODUCTION

Patients with non-muscle-invasive bladder tumor suffer from disease recurrence following transurethral surgery even with intravesical pharmacotherapy, while muscle-invasive disease is often deadly. It is therefore critical to elucidate the underlying molecular mechanisms responsible for not only bladder tumor progression but also its tumorigenesis. Indeed, various molecules and/or signaling pathways have been suggested to contribute to the pathogenesis of bladder cancer.

AREAS COVERED

We summarize the progress during the last few years on the initiation or development, but not progression, of urothelial cancer. The clinical implications of these available data, including prognostic significance and possible application for the prevention of the recurrence of non-muscle-invasive bladder tumors, are also discussed.

EXPERT OPINION

Bladder cancer is a heterogeneous group of neoplasms. The establishment of personalized therapeutic options based on the molecular profile in each case should thus be considered. On that account, further accumulation of data on urothelial tumorigenesis is warranted to identify promising targets for the prevention of postoperative tumor recurrence or tumor development in otherwise high-risk patients.

Advances in understanding of role and mechanism of Hippo signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant tumors, and most patients have a poor prognosis. Many studies have shown that the Hippo signaling pathway plays a key role in the occurrence and development of CRC by regulating CRC cell proliferation and apoptosis, tumor invasion and metastasis, autophagy, metabolic reprogramming, drug resistance, and other processes. This article reviews the latest progress in research of the expression of key molecules of the Hippo signaling pathway in CRC as well as the understanding of the mechanism by which this pathway regulates the occurrence and development of CRC.

Pharmacological blockade of TEAD-YAP reveals its therapeutic limitation in cancer cells

Targeting TEAD autopalmitoylation has been proposed as a therapeutic approach for YAP-dependent cancers. Here we show that TEAD palmitoylation inhibitor MGH-CP1 and analogues block cancer cell "stemness", organ overgrowth and tumor initiation in vitro and in vivo. MGH-CP1 sensitivity correlates significantly with YAP-dependency in a large panel of cancer cell lines. However, TEAD inhibition or YAP/TAZ knockdown leads to transient inhibition of cell cycle progression without inducing cell death, undermining their potential therapeutic utilities. We further reveal that TEAD inhibition or YAP/TAZ silencing leads to VGLL3-mediated transcriptional activation of SOX4/PI3K/AKT signaling axis, which contributes to cancer cell survival and confers therapeutic resistance to TEAD inhibitors. Consistently, combination of TEAD and AKT inhibitors exhibits strong synergy in inducing cancer cell death. Our work characterizes the therapeutic opportunities and limitations of TEAD palmitoylation inhibitors in cancers, and uncovers an intrinsic molecular mechanism, which confers potential therapeutic resistance.

The First Class of Small Molecules Potently Disrupting the YAP-TEAD Interaction by Direct Competition

Inhibition of the YAP-TEAD protein protein interaction is an attractive therapeutic concept under intense investigation with the objective to treat cancers associated with a dysregulation of the Hippo pathway. However, owing to the very extended surface of interaction of the two proteins, the identification of small drug-like molecules able to efficiently prevent YAP from binding to TEAD by direct competition has been elusive so far. We disclose here the discovery of the first class of small molecules potently inhibiting the YAP-TEAD interaction by binding at one of the main interaction sites of YAP at the surface of TEAD. These inhibitors, providing a path forward to pharmacological intervention in the Hippo pathway, evolved from a weakly active virtual screening hit advanced to high potency by structure-based design.

ROCK1 mechano-signaling dependency of human malignancies driven by TEAD/YAP activation

Rho family mechano-signaling through the actin cytoskeleton positively regulates physiological TEAD/YAP transcription, while the evolutionarily conserved Hippo tumor suppressor pathway antagonizes this transcription through YAP cytoplasmic localization/degradation. The mechanisms responsible for oncogenic dysregulation of these pathways, their prevalence in tumors, as well as how such dysregulation can be therapeutically targeted are not resolved. We demonstrate that p53 DNA contact mutants in human tumors, indirectly hyperactivate RhoA/ROCK1/actomyosin signaling, which is both necessary and sufficient to drive oncogenic TEAD/YAP transcription. Moreover, we demonstrate that recurrent lesions in the Hippo pathway depend on physiological levels of ROCK1/actomyosin signaling for oncogenic TEAD/YAP transcription. Finally, we show that ROCK inhibitors selectively antagonize proliferation and motility of human tumors with either mechanism. Thus, we identify a cancer driver paradigm and a precision medicine approach for selective targeting of human malignancies driven by TEAD/YAP transcription through mechanisms that either upregulate or depend on homeostatic RhoA mechano-signaling.

Network Analyses Based on Machine Learning Methods to Quantify Effects of Peptide-Protein Complexes as Drug Targets Using Cinnamon in Cardiovascular Diseases and Metabolic Syndrome as a Case Study

Peptide-protein complexes play important roles in multiple diseases such as cardiovascular diseases (CVDs) and metabolic syndrome (MetS). The peptides may be the key molecules in the designing of inhibitors or drug targets. Many Chinese traditional drugs are shown to play various roles in different diseases, and comprehensive analyses should be performed using networks which could offer more information than results generated from a single level. In this study, a network analysis pipeline was designed based on machine learning methods to quantify the effects of peptide-protein complexes as drug targets. Three steps, namely, pathway filter, combined network construction, and biomarker prediction and validation based on peptides, were performed using cinnamon (CA) in CVDs and MetS as a case. Results showed that 17 peptide-protein complexes including six peptides and four proteins were identified as CA targets. The expressions of AKT1, AKT2, and ENOS were tested using qRT-PCR in a mouse model that was constructed. AKT2 was shown to be a CA-indicating biomarker, while E2F1 and ENOS were CA treatment targets. AKT1 was considered a diabetic responsive biomarker because it was down-regulated in diabetic but not related to CA. Taken together, the pipeline could identify new drug targets based on biological function analyses. This may provide a deep understanding of the drugs' roles in different diseases which may foster the development of peptide-protein complex-based therapeutic approaches.

The regulatory networks of the Hippo signaling pathway in cancer development

The Hippo signaling pathway is a relatively young tumor-related signaling pathway. Although it was discovered lately, research on it developed rapidly. The Hippo signaling pathway is closely relevant to the occurrence and development of tumors and the maintenance of organ size and other biological processes. This manuscript focuses on YAP, the core molecule of the Hippo signaling pathway, and discussion the upstream and downstream regulatory networks of the Hippo signaling pathway during tumorigenesis and development. It also summarizes the relevant drugs involved in this signaling pathway, which may be helpful to the development of targeted drugs for cancer therapy.

Metformin and Niclosamide Synergistically Suppress Wnt and YAP in APC-Mutated Colorectal Cancer

Simple Summary

Hyperactivation of the canonical Wnt and inactivation of the Hippo pathway are well-known genetic backgrounds for familial adenomatosis polyposis (FAP) and colorectal cancer (CRC), although the reciprocal regulation between those pathways is not yet clear. In this study, we found that Axin2, a bona fide downstream target of canonical Wnt, activates the Hippo pathway in APC-mutated CRC, limiting the therapeutic potential of niclosamide on advanced CRC through the inactivation of the Hippo pathway. To overcome the limitation, we combined niclosamide with AMPK activator metformin to activate Hippo and found that this combination synergistically suppressed canonical Wnt and activated Hippo in APC-mutated CRC. Using patient-derived cancer organoid and an APC-MIN mice model, we found the combinatory approach to be effective for APC-mutated CRC. Our results provide not only the reciprocal link between Wnt and Hippo in APC-mutated CRC, but they also provide an effective therapeutic approach with clinically available drugs for FAP and CRC patients.

Abstract

The Wnt and Hippo pathways are tightly coordinated and understanding their reciprocal regulation may provide a novel therapeutic strategy for cancer. Anti-helminthic niclosamide is an effective inhibitor of Wnt and is now in a phase II trial for advanced colorectal cancer (CRC) patients. We found that Axin2, an authentic target gene of canonical Wnt, acts as aYAP phosphorylation activator in APC-mutated CRC. While niclosamide effectively suppresses Wnt, it also inhibits Hippo, limiting its therapeutic potential for CRC. To overcome this limitation, we utilized metformin, a clinically available AMPK activator. This combinatory approach not only suppresses canonical Wnt activity, but also inhibits YAP activity in CRC cancer cells and in patient-derived cancer organoid through the suppression of cancer stemness. Further, combinatory oral administration suppressed in vivo tumorigenesis and the cancer progression of APC-MIN mice models. Our observations provide not only a reciprocal link between Wnt and Hippo, but also clinically available novel therapeutics that are able to target Wnt and YAP in APC-mutated CRC.

Advances in targeting 'undruggable' transcription factors with small molecules

Transcription factors (TFs) represent key biological players in diseases including cancer, autoimmunity, diabetes and cardiovascular disease. However, outside nuclear receptors, TFs have traditionally been considered 'undruggable' by small-molecule ligands due to significant structural disorder and lack of defined small-molecule binding pockets. Renewed interest in the field has been ignited by significant progress in chemical biology approaches to ligand discovery and optimization, especially the advent of targeted protein degradation approaches, along with increasing appreciation of the critical role a limited number of collaborators play in the regulation of key TF effector genes. Here, we review current understanding of TF-mediated gene regulation, discuss successful targeting strategies and highlight ongoing challenges and emerging approaches to address them.

Activation of the tumor suppressive Hippo pathway by triptonide as a new strategy to potently inhibit aggressive melanoma cell metastasis

Metastatic melanoma has a very high mortality rate despite the availability of chemotherapy, radiotherapy, and immunotherapy; therefore, more effective therapeutics are needed. The Hippo pathway plays an inhibitory role in melanoma progression, but the tumor suppressors Salvador homolog-1 (SAV1) and large tumor suppressor 1 (LATS1) in this pathway are down-regulated in melanoma. As a result, the downstream oncogenic Yes-associated protein (YAP) is active, resulting in uncontrolled melanoma growth and metastasis. Therapeutics for remedying SAV1 and LATS1 deficiency in melanoma have not yet been reported in the literature. Here, we show that the small molecule triptonide (MW 358 Da) robustly suppressed melanoma cell tumorigenicity, migration, and invasion. Furthermore, triptonide markedly reduced tumor growth and melanoma lung metastasis in tumor-bearing mice with low toxicity. Molecular mechanistic studies revealed that triptonide promoted SAV1 and LATS1 expression, strongly activated the tumor-suppressive Hippo pathway, degraded oncogenic YAP via the lysosomal pathway, and reduced levels of tumorigenic microphthalmia-associated transcription factor (MITF) in melanoma cells. Triptonide also strongly inhibited activation of AKT, a SAV1-binding signaling protein. Collectively, our results conceptually demonstrate that induction of SAV1 and LATS1 expression and activation of the tumor-suppressive Hippo pathway by triptonide potently inhibits aggressive melanoma cell growth and metastasis. These findings suggest a new strategy for developing therapeutics to treat metastatic melanoma and highlight a novel drug candidate against aggressive melanoma.

The novel potent TEAD inhibitor, K-975, inhibits YAP1/TAZ-TEAD protein-protein interactions and exerts an anti-tumor effect on malignant pleural mesothelioma

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.

A new perspective on the interaction between the Vg/VGLL1-3 proteins and the TEAD transcription factors

The most downstream elements of the Hippo pathway, the TEAD transcription factors, are regulated by several cofactors, such as Vg/VGLL1-3. Earlier findings on human VGLL1 and here on human VGLL3 show that these proteins interact with TEAD via a conserved amino acid motif called the TONDU domain. Surprisingly, our studies reveal that the TEAD-binding domain of Drosophila Vg and of human VGLL2 is more complex and contains an additional structural element, an Ω-loop, that contributes to TEAD binding. To explain this unexpected structural difference between proteins from the same family, we propose that, after the genome-wide duplications at the origin of vertebrates, the Ω-loop present in an ancestral VGLL gene has been lost in some VGLL variants. These findings illustrate how structural and functional constraints can guide the evolution of transcriptional cofactors to preserve their ability to compete with other cofactors for binding to transcription factors.

Cardiac Regeneration After Myocardial Infarction: an Approachable Goal

Purpose of Review

Until recently, cardiac regeneration after myocardial infarction has remained a holy grail in cardiology. Failure of clinical trials using adult stem cells and scepticism about the actual existence of such cells has reinforced the notion that the heart is an irreversibly post-mitotic organ. Recent evidence has drastically challenged this conclusion.

Recent Findings

Cardiac regeneration can successfully be obtained by at least two strategies. First, new cardiomyocytes can be generated from embryonic stem cells or induced pluripotent stem cells and administered to the heart either as cell suspensions or upon ex vivo generation of contractile myocardial tissue. Alternatively, the endogenous capacity of cardiomyocytes to proliferate can be stimulated by the delivery of individual genes or, more successfully, of selected microRNAs.

Summary

Recent experimental success in large animals by both strategies now fuels the notion that cardiac regeneration is indeed possible. Several technical hurdles, however, still need to be addressed and solved before broad and successful clinical application is achieved.

Targeting Hippo signaling pathway by phytochemicals in cancer therapy

The current era of cancer research has been continuously advancing upon identifying novel aspects of tumorigenesis and the principal mechanisms behind the unleashed proliferation, invasion, drug resistance and immortality of cancer cells in hopes of exploiting these findings to achieve a more effective treatment for cancer. In pursuit of this goal, the identification of the first components of an extremely important regulatory pathway in Drosophila melanogaster that largely determines cell fate during the developmental stages, ended up in the discovery of the highly sophisticated Hippo signaling cascade. Soon after, it was revealed that deregulation of the components of this pathway either via mutations or through epigenetic alterations can be observed in a vast variety of tumors and these alterations greatly contribute to the neoplastic transformation of cells, their survival, growth and resistance to therapy. As more hidden aspects of this pathway such as its widespread entanglement with other major cellular signaling pathways are continuously being uncovered, many researchers have sought over the past decade to find ways of therapeutic interventions targeting the major components of the Hippo cascade. To date, various approaches such as the use of exogenous targeting miRNAs and different molecular inhibitors have been recruited herein, among which naturally occurring compounds have shown a great promise. On such a basis, in the present work we review the current understanding of Hippo pathway and the most recent evidence on targeting its components using natural plant-derived phytochemicals.

Gene Therapy for the Heart Lessons Learned and Future Perspectives

While clinical gene therapy celebrates its first successes, with several products already approved for clinical use and several hundreds in the final stages of the clinical approval pipeline, there is not a single gene therapy approach that has worked for the heart. Here, we review the past experience gained in the several cardiac gene therapy clinical trials that had the goal of inducing therapeutic angiogenesis in the ischemic heart and in the attempts at modulating cardiac function in heart failure. Critical assessment of the results so far achieved indicates that the efficiency of cardiac gene delivery remains a major hurdle preventing success but also that improvements need to be sought in establishing more reliable large animal models, choosing more effective therapeutic genes, better designing clinical trials, and more deeply understanding cardiac biology. We also emphasize a few areas of cardiac gene therapy development that hold great promise for the future. In particular, the transition from gene addition studies using protein-coding cDNAs to the modulation of gene expression using small RNA therapeutics and the improvement of precise gene editing now pave the way to applications such as cardiac regeneration after myocardial infarction and gene correction for inherited cardiomyopathies that were unapproachable until a decade ago.

An Early Association between the α-Helix of the TEAD Binding Domain of YAP and TEAD Drives the Formation of the YAP:TEAD Complex

The Hippo pathway is an evolutionarily conserved signaling pathway that is involved in the control of organ size and development. The TEAD transcription factors are the most downstream elements of the Hippo pathway, and their transcriptional activity is regulated via the interaction with different co-regulators such as YAP. The structure of the YAP:TEAD complex shows that YAP binds to TEAD via two distinct secondary structure elements, an α-helix and an Ω-loop, and site-directed mutagenesis experiments revealed that the Ω-loop is the "hot spot" of this interaction. While much is known about how YAP and TEAD interact with each other, little is known about the mechanism leading to the formation of a complex between these two proteins. Here we combine site-directed mutagenesis with pre-steady-state kinetic measurements to show that the association between these proteins follows an apparent one-step binding mechanism. Furthermore, linear free energy relationships and a Φ analysis suggest that binding-induced folding of the YAP α-helix to TEAD occurs independently of and before formation of the Ω-loop interface. Thus, the binding-induced folding of YAP appears not to conform to the concomitant formation of tertiary structure (nucleation-condensation) usually observed for coupled binding and folding reactions. Our findings demonstrate how a mechanism reminiscent of the classical framework (diffusion-collision) mechanism of protein folding may operate in disorder-to-order transitions involving intrinsically disordered proteins.

A combat with the YAP/TAZ-TEAD oncoproteins for cancer therapy

The transcriptional co-regulators YAP and TAZ pair primarily with the TEAD family of transcription factors to elicit a gene expression signature that plays a prominent role in cancer development, progression and metastasis. YAP and TAZ endow cells with various oncogenic traits such that they sustain proliferation, inhibit apoptosis, maintain stemness, respond to mechanical stimuli, engineer metabolism, promote angiogenesis, suppress immune response and develop resistance to therapies. Therefore, inhibiting YAP/TAZ- TEAD is an attractive and viable option for novel cancer therapy. It is exciting to know that many drugs already in the clinic restrict YAP/TAZ activities and several novel YAP/TAZ inhibitors are currently under development. We have classified YAP/TAZ-inhibiting drugs into three groups. Group I drugs act on the upstream regulators that are stimulators of YAP/TAZ activities. Many of the Group I drugs have the potential to be repurposed as YAP/TAZ indirect inhibitors to treat various solid cancers. Group II modalities act directly on YAP/TAZ or TEADs and disrupt their interaction; targeting TEADs has emerged as a novel option to inhibit YAP/TAZ, as TEADs are major mediators of their oncogenic programs. TEADs can also be leveraged on using small molecules to activate YAP/TAZ-dependent gene expression for use in regenerative medicine. Group III drugs focus on targeting one of the oncogenic downstream YAP/TAZ transcriptional target genes. With the right strategy and impetus, it is not far-fetched to expect a repurposed group I drug or a novel group II drug to combat YAP and TAZ in cancers in the near future.

The Impact of Surgical Margins and Adjuvant Radiotherapy in Patients with Undifferentiated Pleomorphic Sarcomas of the Extremities: A Single-Institutional Analysis of 192 Patients

Background: Undifferentiated pleomorphic sarcomas are a frequent subtype within the heterogeneous group of soft tissue sarcomas. As the attainment of negative margins can be complicated at the extremities, we determined the prognostic significance of surgical margins in our patient population. Methods: We retrospectively determined the relationship between local recurrence-free survival (LRFS), overall survival (OS), and potential prognostic factors in 192 patients with UPS of the extremities who were suitable for surgical treatment in curative intent. The median follow-up time was 5.1 years. Results: The rates of LRFS and OS after 2 years were 75.7% and 87.2% in patients with R0-resected primary tumors and 49.1% and 81.8% in patients with R1/R2-status (LRFS: p = 0.013; OS: p = 0.001). Adjuvant radiotherapy significantly improved LRFS (5-year: 67.6% vs. 48.4%; p < 0.001) and OS (5-year: 82.8 vs. 61.8; p = 0.016). Both, negative margins and adjuvant radiotherapy were found to be independent prognostic factors in multivariate analysis. Conclusions: The data from this study could underscore the beneficial prognostic impact of negative margins on LRFS and OS. However, the width of negative margins seemed to be not relevant. Notably, adjuvant radiotherapy was not only able to decrease the risk of local failure but also improved OS in a significant manner.