YAP1

Gene Summary

Gene:YAP1; Yes-associated protein 1
Aliases: YAP, YKI, COB1, YAP2, YAP65
Location:11q13
Summary:This gene encodes a downstream nuclear effector of the Hippo signaling pathway which is involved in development, growth, repair, and homeostasis. This gene is known to play a role in the development and progression of multiple cancers as a transcriptional regulator of this signaling pathway and may function as a potential target for cancer treatment. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Aug 2013]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:transcriptional coactivator YAP1
HPRD
Source:NCBIAccessed: 27 February, 2015

Ontology:

What does this gene/protein do?
Show (34)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 27 February 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Protein-Serine-Threonine Kinases
  • Gene Expression Profiling
  • Brain Tumours
  • Hepatocellular Carcinoma
  • Survival Rate
  • RT-PCR
  • Signal Transduction
  • Nuclear Proteins
  • Tumor Suppressor Gene
  • Phosphorylation
  • Signal Transducing Adaptor Proteins
  • Intercellular Signaling Peptides and Proteins
  • Tissue Array Analysis
  • Knockout Mice
  • Liver Cancer
  • Neoplasm Proteins
  • Messenger RNA
  • MicroRNAs
  • Adenocarcinoma
  • Genetic Predisposition
  • Proto-Oncogene Proteins
  • Down-Regulation
  • Cell Proliferation
  • Young Adult
  • RTPCR
  • Neoplastic Cell Transformation
  • ras GTPase-Activating Proteins
  • Tumor Suppressor Proteins
  • Transcriptional Activation
  • Tumor Markers
  • Chromosome 11
  • Apoptosis
  • Cell Movement
  • Western Blotting
  • Promoter Regions
  • siRNA
  • Phosphoproteins
  • Breast Cancer
  • Cancer Gene Expression Regulation
  • DNA-Binding Proteins
  • Immunohistochemistry
Tag cloud generated 27 February, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: YAP1 (cancer-related)

Liang N, Zhang C, Dill P, et al.
Regulation of YAP by mTOR and autophagy reveals a therapeutic target of tuberous sclerosis complex.
J Exp Med. 2014; 211(11):2249-63 [PubMed] Article available free on PMC after 20/04/2015 Related Publications
Genetic studies have shown that the tuberous sclerosis complex (TSC) 1-TSC2-mammalian target of Rapamycin (mTOR) and the Hippo-Yes-associated protein 1 (YAP) pathways are master regulators of organ size, which are often involved in tumorigenesis. The crosstalk between these signal transduction pathways in coordinating environmental cues, such as nutritional status and mechanical constraints, is crucial for tissue growth. Whether and how mTOR regulates YAP remains elusive. Here we describe a novel mouse model of TSC which develops renal mesenchymal lesions recapitulating human perivascular epithelioid cell tumors (PEComas) from patients with TSC. We identify that YAP is up-regulated by mTOR in mouse and human PEComas. YAP inhibition blunts abnormal proliferation and induces apoptosis of TSC1-TSC2-deficient cells, both in culture and in mosaic Tsc1 mutant mice. We further delineate that YAP accumulation in TSC1/TSC2-deficient cells is due to impaired degradation of the protein by the autophagosome/lysosome system. Thus, the regulation of YAP by mTOR and autophagy is a novel mechanism of growth control, matching YAP activity with nutrient availability under growth-permissive conditions. YAP may serve as a potential therapeutic target for TSC and other diseases with dysregulated mTOR activity.

Ma L, Pan Q, Sun F, et al.
Cluster of differentiation 166 (CD166) regulates cluster of differentiation (CD44) via NF-κB in liver cancer cell line Bel-7402.
Biochem Biophys Res Commun. 2014; 451(2):334-8 [PubMed] Related Publications
Cluster of differentiation 166 (CD166) is critical for liver cancer cell survival. Our previously study demonstrated that CD166 exerts its anti-apoptotic role through interaction with YAP in liver cancer. However, the interaction between CD166 and other cell surface molecules remains unclear in liver cancer cells. In the current study, we found that both mRNA and protein of CD44 expression was significantly inhibited by knocking-down CD166. Moreover, CD166 affected-CD44 expression is dependent of transcription via blocking NF-κB pathway. On the contrary, CD44 promoted up-regulation of CD166 mRNA and protein. And it may be through E3 ubiquitin ligases COP1 and UBC3 to regulate CD166 protein degradation. Collectively, these results suggest that CD166 and CD44 play important roles in liver cancer development. Therefore, CD166 may develop as a potential therapeutic molecule target for the treatment of liver cancer.

Tremblay AM, Missiaglia E, Galli GG, et al.
The Hippo transducer YAP1 transforms activated satellite cells and is a potent effector of embryonal rhabdomyosarcoma formation.
Cancer Cell. 2014; 26(2):273-87 [PubMed] Related Publications
The role of the Hippo pathway effector YAP1 in soft tissue sarcomas is poorly defined. Here we report that YAP1 activity is elevated in human embryonal rhabdomyosarcoma (ERMS). In mice, sustained YAP1 hyperactivity in activated, but not quiescent, satellite cells induces ERMS with high penetrance and short latency. Via its transcriptional program with TEAD1, YAP1 directly regulates several major hallmarks of ERMS. YAP1-TEAD1 upregulate pro-proliferative and oncogenic genes and maintain the ERMS differentiation block by interfering with MYOD1 and MEF2 pro-differentiation activities. Normalization of YAP1 expression reduces tumor burden in human ERMS xenografts and allows YAP1-driven ERMS to differentiate in situ. Collectively, our results identify YAP1 as a potent ERMS oncogenic driver and a promising target for differentiation therapy.

Li W, Cooper J, Zhou L, et al.
Merlin/NF2 loss-driven tumorigenesis linked to CRL4(DCAF1)-mediated inhibition of the hippo pathway kinases Lats1 and 2 in the nucleus.
Cancer Cell. 2014; 26(1):48-60 [PubMed] Article available free on PMC after 14/07/2015 Related Publications
It is currently unclear whether Merlin/NF2 suppresses tumorigenesis by activating upstream components of the Hippo pathway at the plasma membrane or by inhibiting the E3 ubiquitin ligase CRL4(DCAF1) in the nucleus. We found that derepressed CRL4(DCAF1) promotes YAP- and TEAD-dependent transcription by ubiquitylating and, thereby, inhibiting Lats1 and 2 in the nucleus. Genetic epistasis experiments and analysis of tumor-derived missense mutations indicate that this signaling connection sustains the oncogenicity of Merlin-deficient tumor cells. Analysis of clinical samples confirms that this pathway operates in NF2-mutant tumors. We conclude that derepressed CRL4(DCAF1) promotes activation of YAP by inhibiting Lats1 and 2 in the nucleus.

Ong M, Carreira S, Goodall J, et al.
Validation and utilisation of high-coverage next-generation sequencing to deliver the pharmacological audit trail.
Br J Cancer. 2014; 111(5):828-36 [PubMed] Article available free on PMC after 26/08/2015 Related Publications
BACKGROUND: Predictive biomarker development is a key challenge for novel cancer therapeutics. We explored the feasibility of next-generation sequencing (NGS) to validate exploratory genomic biomarkers that impact phase I trial selection.
METHODS: We prospectively enrolled 158 patients with advanced solid tumours referred for phase I clinical trials at the Royal Marsden Hospital (October 2012 to March 2013). After fresh and/or archived tumour tissue were obtained, 93 patients remained candidates for phase I trials. Results from tumour sequencing on the Illumina MiSeq were cross-validated in 27 out of 93 patients on the Ion Torrent Personal Genome Machine (IT-PGM) blinded to results. MiSeq validation with Sequenom MassARRAY OncoCarta 1.0 (Sequenom Inc., San Diego, CA, USA) was performed in a separate cohort.
RESULTS: We found 97% concordance of mutation calls by MiSeq and IT-PGM at a variant allele frequency ⩾13% and ⩾500 × depth coverage, and 91% concordance between MiSeq and Sequenom. Common 'actionable' mutations involved deoxyribonucleic acid (DNA) repair (51%), RAS-RAF-MEK (35%), Wnt (26%), and PI3K-AKT-mTOR (24%) signalling. Out of 53, 29 (55%) patients participating in phase I trials were recommended based on identified actionable mutations.
CONCLUSIONS: Targeted high-coverage NGS panels are a highly feasible single-centre technology well-suited to cross-platform validation, enrichment of trials with molecularly defined populations and hypothesis testing early in drug development.

Shao DD, Xue W, Krall EB, et al.
KRAS and YAP1 converge to regulate EMT and tumor survival.
Cell. 2014; 158(1):171-84 [PubMed] Article available free on PMC after 03/07/2015 Related Publications
Cancer cells that express oncogenic alleles of RAS typically require sustained expression of the mutant allele for survival, but the molecular basis of this oncogene dependency remains incompletely understood. To identify genes that can functionally substitute for oncogenic RAS, we systematically expressed 15,294 open reading frames in a human KRAS-dependent colon cancer cell line engineered to express an inducible KRAS-specific shRNA. We found 147 genes that promoted survival upon KRAS suppression. In particular, the transcriptional coactivator YAP1 rescued cell viability in KRAS-dependent cells upon suppression of KRAS and was required for KRAS-induced cell transformation. Acquired resistance to Kras suppression in a Kras-driven murine lung cancer model also involved increased YAP1 signaling. KRAS and YAP1 converge on the transcription factor FOS and activate a transcriptional program involved in regulating the epithelial-mesenchymal transition (EMT). Together, these findings implicate transcriptional regulation of EMT by YAP1 as a significant component of oncogenic RAS signaling.

Mortus JR, Zhang Y, Hughes DP
Developmental pathways hijacked by osteosarcoma.
Adv Exp Med Biol. 2014; 804:93-118 [PubMed] Related Publications
Cancer of any type often can be described by an arrest, alteration or disruption in the normal development of a tissue or organ, and understanding of the normal counterpart's development can aid in understanding the malignant state. This is certainly true for osteosarcoma and the normal developmental pathways that guide osteoblast development that are changed in the genesis of osteogenic sarcoma. A carefully regulated crescendo-decrescendo expression of RUNX2 accompanies the transition from mesenchymal stem cell to immature osteoblast to mature osteoblast. This pivotal role is controlled by several pathways, including bone morphogenic protein (BMP), Wnt/β-catenin, fibroblast growth factor (FGF), and protein kinase C (PKC). The HIPPO pathway and its downstream target YAP help to regulate proliferation of immature osteoblasts and their maturation into non-proliferating mature osteoblasts. This pathway also helps regulate expression of the mature osteoblast protein osteocalcin. YAP also regulates expression of MT1-MMP, a membrane-bound matrix metalloprotease responsible for remodeling the extracellular matrix surrounding the osteoblasts. YAP, in turn, can be regulated by the ERBB family protein Her-4. Osteosarcoma may be thought of as a cell held at the immature osteoblast stage, retaining some of the characteristics of that developmental stage. Disruptions of several of these pathways have been described in osteosarcoma, including BMP, Wnt/b-catenin, RUNX2, HIPPO/YAP, and Her-4. Further, PKC can be activated by several receptor tyrosine kinases implicated in osteosarcoma, including the ERBB family (EGFR, Her-2 and Her-4 in osteosarcoma), IGF1R, FGF, and others. Understanding these functions may aid in the understanding the mechanisms underpinning clinical observations in osteosarcoma, including both the lytic and blastic phenotypes of tumors, the invasiveness of the disease, and the tendency for treated tumors to ossify rather than shrink. Through a better understanding of the relationship between normal osteoblast development and osteosarcoma, we may gain insights into novel therapeutic avenues and improved outcomes.

Christensen LL, Holm A, Rantala J, et al.
Functional screening identifies miRNAs influencing apoptosis and proliferation in colorectal cancer.
PLoS One. 2014; 9(6):e96767 [PubMed] Article available free on PMC after 03/07/2015 Related Publications
MicroRNAs (miRNAs) play a critical role in many biological processes and are aberrantly expressed in human cancers. Particular miRNAs function either as tumor suppressors or oncogenes and appear to have diagnostic and prognostic significance. Although numerous miRNAs are dys-regulated in colorectal cancer (CRC) only a small fraction has been characterized functionally. Using high-throughput functional screening and miRNA profiling of clinical samples the present study aims at identifying miRNAs important for the control of cellular growth and/or apoptosis in CRC. The high-throughput functional screening was carried out in six CRC cell lines transfected with a pre-miR library including 319 synthetic human pre-miRs. Phenotypic alterations were evaluated by immunostaining of cleaved cPARP (apoptosis) or MKI67 (proliferation). Additionally, TaqMan Human MicroRNA Array Set v2.0 was used to profile the expression of 667 miRNAs in 14 normal colon mucosa and 46 microsatellite stable stage II CRC patients. Among the miRNAs that induced growth arrest and apoptosis in the CRC cell lines, and at same time were dys-regulated in the clinical samples, miR-375 was selected for further analysis. Independent in vitro analysis of transient and stable transfected CRC cell lines confirmed that miR-375 reduces cell viability through the induction of apoptotic death. We identified YAP1 as a direct miR-375 target in CRC and show that HELLS and NOLC1 are down-stream targets. Knock-down of YAP1 mimicked the phenotype induced by miR-375 over-expression indicating that miR-375 most likely exerts its pro-apoptotic role through YAP1 and its anti-apoptotic down-stream targets BIRC5 and BCL2L1. Finally, in vivo analysis of mouse xenograft tumors showed that miR-375 expression significantly reduced tumor growth. We conclude that the high-throughput screening successfully identified miRNAs that induce apoptosis and/or inhibit proliferation in CRC cells. Finally, combining the functional screening with profiling of CRC tissue samples we identified clinically relevant miRNAs and miRNA targets in CRC.

Castilla MÁ, López-García MÁ, Atienza MR, et al.
VGLL1 expression is associated with a triple-negative basal-like phenotype in breast cancer.
Endocr Relat Cancer. 2014; 21(4):587-99 [PubMed] Related Publications
Vestigial-like 1 (VGLL1) is a poorly characterized gene encoding a transcriptional co-activator structurally homologous to TAZ and YAP that modulates the Hippo pathway in Drosophila. In this study, we examined the expression of VGLL1 and its intronic miRNA, miR-934, in breast cancer. VGLL1 and miR-934 expression miRNA profiling was carried out on frozen samples of grade 3 invasive ductal carcinomas. VGLL1 protein was also examined in 433 sporadic and BRCA1-associated breast carcinomas on tissue microarrays. RNA-seq data from The Cancer Genome Atlas (TCGA) was used to confirm differences in VGLL1 and miR-934 expression in different breast cancer subtypes, and to correlate their expression with that of other genes and miRNAs. Of 28 miRNAs differentially expressed in estrogen receptor (ER)-positive and ER-negative grade 3 breast carcinomas, miR-934 was most strongly upregulated in ER-negative carcinomas, and its expression was correlated with that of VGLL1. Nuclear VGLL1 expression was observed in 13% of sporadic breast carcinomas, and while VGLL1 was only occasionally found in luminal A (0.70%) and B (5.60%) carcinomas, it was often expressed in HER2-positive (17%), triple-negative (TN) breast carcinomas (>40%) and BRCA1-associated TN carcinomas (>50%). These findings were confirmed in the TCGA dataset, which revealed positive associations with luminal progenitor genes (GABRP, SLC6A14, FOXC1, PROM1, and BBOX1) and strong negative correlations with ER-associated genes (ESR1, C6ORF211, GATA3, and FOXA1). Moreover, VGLL1 expression was associated with reduced overall survival. In conclusion, VGLL1 and miR-934 are mainly expressed in sporadic and BRCA1-associated TN basal-like breast carcinomas, and their coordinated expression, at least partially mediated by the direct modulation of ESR1, might be involved in the maintenance of a luminal progenitor phenotype.

Yu W, Wang J, Ma L, et al.
CD166 plays a pro-carcinogenic role in liver cancer cells via inhibition of FOXO proteins through AKT.
Oncol Rep. 2014; 32(2):677-83 [PubMed] Related Publications
Cluster of differentiation 166 (CD166) is a cell surface membrane protein, which is regarded as a valuable prognostic marker in several types of epithelial tumors. We previously reported that CD166 exerts its pro-carcinogenic role by enhancing YAP function in liver cancer cells. However, YAP cannot completely rescue the increased anti‑carcinogenic effects by gene silencing of CD166, whose downstream effectors require further investigation. Here, we found that knockdown of CD166 inhibits phosphorylation of anti-carcinogenic FOXO proteins. Overexpression of CD166 led, not only to a faster protein degradation rate, but also a more accumulated ubiquitination of FOXO compared to the control. Moreover, overexpression of CD166 facilitated FOXO protein localization from the nuclear fraction to the cytosolic fraction, suggesting that CD166 modulates FOXO protein stability through alteration of their subcellular localization. In addition, simultaneous overexpression of CD166 partially reversed the evoked anti-carcinogenic effects by overexpression of FOXO both in vitro and in vivo. Furthermore, CD166 knockdown‑induced anti‑carcinogenic effects and dephosphorylation of FOXO proteins were rescued by overexpression of AKT. In liver cancer tissues, we also observed that higher expression levels of CD166, phospho-AKT, total AKT and phospho‑FOXO were correlated with lower expression levels of total FOXO, suggesting that the upregulation of CD166 leads to the activation of AKT, which in turn facilitates phosphorylation and degradation of FOXO. Taken together, our data demonstrate that AKT is an inter-mediator between the upstream regulator, CD166, and downstream effector, FOXO, in liver cancer cells. Disrupting the relationship between CD166 and the AKT/FOXO axis may serve as a novel therapeutic target for liver cancer patients.

Tu K, Yang W, Li C, et al.
Fbxw7 is an independent prognostic marker and induces apoptosis and growth arrest by regulating YAP abundance in hepatocellular carcinoma.
Mol Cancer. 2014; 13:110 [PubMed] Article available free on PMC after 03/07/2015 Related Publications
BACKGROUND: The E3 ubiquitin ligase Fbxw7 functions as a general tumor suppressor by targeting several well-known oncoproteins for ubiquitination and proteasomal degradation. However, the clinical significance of Fbxw7 and the mechanisms involved in the anti-cancer effect of Fbxw7 in HCC are not clear.
METHOD: The Fbxw7 and YAP expression in 60 samples of surgical resected HCC and matched normal tumor-adjacent tissues were assessed using IHC or immunoblotting. Flow cytometry, caspase 3/7 activity assay, BrdU cell proliferation assay and MTT assay were used to detect proliferation and apoptosis of HCC cells. The regulatory effect of Fbxw7 on YAP in HCC cells was confirmed by qRT-PCR, immunoblotting and immunofluorescence. Co-immunoprecipitation was used to analyze interaction between YAP and Fbxw7. Nude mice subcutaneous injection, Ki-67 staining and TUNEL assay were used to evaluate tumor growth and apoptosis in vivo.
RESULTS: In this study, we found that Fbxw7 expression was impaired in HCC tissues and loss of Fbxw7 expression was correlated with poor clinicopathological features including large tumor size, venous infiltration, high pathological grading and advanced TNM stage. Additionally, we demonstrated that patients with positive Fbxw7 expression had a better 5-year survival and Fbxw7 was an independent factor for predicting the prognosis of HCC patients. We confirmed that Fbxw7 inhibited HCC by inducing both apoptosis and growth arrest. Elevated YAP expression was observed in the same cohort of HCC tissues. Pearson's correlation coefficient analysis indicated that Fbxw7 was inversely associated with YAP protein expression in HCC tissues. We also found that Fbxw7 regulated YAP protein abundance by targeting YAP for ubiquitination and proteasomal degradation in HCC. Furthermore, restoring YAP expression partially abrogated Fbxw7 induced HCC cell apoptosis and growth arrest in vitro and in vivo.
CONCLUSION: These results indicate that Fbxw7 may serve as a prognostic marker and that YAP may be a potential target of Fbxw7 in HCC.

Feng X, Degese MS, Iglesias-Bartolome R, et al.
Hippo-independent activation of YAP by the GNAQ uveal melanoma oncogene through a trio-regulated rho GTPase signaling circuitry.
Cancer Cell. 2014; 25(6):831-45 [PubMed] Article available free on PMC after 16/06/2015 Related Publications
Mutually exclusive activating mutations in the GNAQ and GNA11 oncogenes, encoding heterotrimeric Gαq family members, have been identified in ∼ 83% and ∼ 6% of uveal and skin melanomas, respectively. However, the molecular events underlying these GNAQ-driven malignancies are not yet defined, thus limiting the ability to develop cancer-targeted therapies. Here, we focused on the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway that controls organ size. We found that Gαq stimulates YAP through a Trio-Rho/Rac signaling circuitry promoting actin polymerization, independently of phospholipase Cβ and the canonical Hippo pathway. Furthermore, we show that Gαq promotes the YAP-dependent growth of uveal melanoma cells, thereby identifying YAP as a suitable therapeutic target in uveal melanoma, a GNAQ/GNA11-initiated human malignancy.

Han SX, Bai E, Jin GH, et al.
Expression and clinical significance of YAP, TAZ, and AREG in hepatocellular carcinoma.
J Immunol Res. 2014; 2014:261365 [PubMed] Article available free on PMC after 16/06/2015 Related Publications
PURPOSE: Yes-associated protein (YAP) and PDZ-binding motif (TAZ) are two important effectors of Hippo pathway controlling the balance of organ size and carcinogenesis. Amphiregulin (AREG) is a member of the epidermal growth factor family, a direct target gene of YAP and TAZ. The role of these proteins in hepatocellular carcinoma (HCC) is unclear.
METHODS: The expression of YAP, TAZ, and AREG in HCC was analyzed by immunohistochemical staining. The level of secreted serum AREG was also assayed by enzyme-linked immunosorbent (ELISA) assay.
RESULTS: YAP, TAZ, and AREG were expressed in 69.2% (27/39), 66.7% (26/39), and 61.5% (24/39) of HCC patients. The expression of YAP was significantly correlated with Edmondson stage (P>0.05), serum AFP level (P>0.05), and HCC prognosis (P>0.05). AREG expression was also significantly correlated with Edmondson stage (P>0.05) and serum AFP level (P>0.05). In addition, the expression of serum AREG was higher than serum AFP in HCC patients. Further multivariate analysis showed that YAP expression was an independent prognostic factor that significantly affected the overall survival of HCC patients.
CONCLUSIONS: YAP maybe an independent prognostic indicator for HCC patients and serum AREG may be a serological biomarker of HCC.

Tao J, Calvisi DF, Ranganathan S, et al.
Activation of β-catenin and Yap1 in human hepatoblastoma and induction of hepatocarcinogenesis in mice.
Gastroenterology. 2014; 147(3):690-701 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
BACKGROUND & AIMS: Aberrant activation of β-catenin and Yes-associated protein 1 (Yap1) signaling pathways have been associated with the development of multiple tumor types. Yap functions as a transcriptional coactivator by interacting with TEA domain DNA binding proteins. We investigated the interactions among these pathways during hepatic tumorigenesis.
METHODS: We used immunohistochemical analysis to determine expression of β-catenin and Yap1 in liver cancer specimens collected from patients in Europe and the United States, consisting of 104 hepatocellular carcinoma, 62 intrahepatic cholangiocarcinoma, and 94 hepatoblastoma samples. We assessed β-catenin and Yap1 signaling and interactions in hepatoblastoma cell lines ((HuH6, HepG2, HepT1, HC-AFW1, HepG2, and HC-AFW1); proteins were knocked down with small interfering RNAs, and effects on proliferation and cell death were measured. Sleeping beauty-mediated hydrodynamic transfection was used to overexpress constitutively active forms of β-catenin (ΔN90/β-catenin) and Yap1 (YapS127A) in livers of mice; tissues were collected, and histological and immunohistochemical analyses were performed.
RESULTS: We observed nuclear localization of β-catenin and Yap1 in 79% of hepatoblastoma samples but not in most hepatocellular carcinoma or intrahepatic cholangiocarcinoma samples. Yap1 and β-catenin coprecipitated in hepatoblastoma but not hepatocellular carcinoma cells. Small interfering RNA-mediated knockdown of Yap1 or β-catenin in hepatoblastoma cells reduced proliferation in an additive manner. Knockdown of Yap1 reduced its ability to coactivate transcription with β-catenin; β-catenin inhibitors inactivated Yap1. Overexpression of constitutively active forms of Yap1 and β-catenin in mouse liver led to rapid tumorigenesis, with 100% mortality by 11 weeks. Tumor cells expressed both proteins, and human hepatoblastoma cells expressed common targets of their 2 signaling pathways. Yap1 binding of TEA domain factors was required for tumorigenesis in mice.
CONCLUSIONS: β-catenin and the transcriptional regulator Yap1 interact physically and are activated in most human hepatoblastoma tissues; overexpression of activated forms of these proteins in livers of mice leads to rapid tumor development. Further analysis of these mice will allow further studies of these pathways in hepatoblastoma pathogenesis and could lead to the identification of new therapeutic targets.

Cottini F, Hideshima T, Xu C, et al.
Rescue of Hippo coactivator YAP1 triggers DNA damage-induced apoptosis in hematological cancers.
Nat Med. 2014; 20(6):599-606 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
Oncogene-induced DNA damage elicits genomic instability in epithelial cancer cells, but apoptosis is blocked through inactivation of the tumor suppressor p53. In hematological cancers, the relevance of ongoing DNA damage and the mechanisms by which apoptosis is suppressed are largely unknown. We found pervasive DNA damage in hematologic malignancies, including multiple myeloma, lymphoma and leukemia, which leads to activation of a p53-independent, proapoptotic network centered on nuclear relocalization of ABL1 kinase. Although nuclear ABL1 triggers cell death through its interaction with the Hippo pathway coactivator YAP1 in normal cells, we show that low YAP1 levels prevent nuclear ABL1-induced apoptosis in these hematologic malignancies. YAP1 is under the control of a serine-threonine kinase, STK4. Notably, genetic inactivation of STK4 restores YAP1 levels, triggering cell death in vitro and in vivo. Our data therefore identify a new synthetic-lethal strategy to selectively target cancer cells presenting with endogenous DNA damage and low YAP1 levels.

Zhao Y, Khanal P, Savage P, et al.
YAP-induced resistance of cancer cells to antitubulin drugs is modulated by a Hippo-independent pathway.
Cancer Res. 2014; 74(16):4493-503 [PubMed] Related Publications
Although antitubulin drugs are used widely to treat human cancer, many patients display intrinsic or acquired drug resistance that imposes major obstacles to successful therapy. Mounting evidence argues that cancer cell apoptosis triggered by antitubulin drugs relies upon activation of the cell-cycle kinase Cdk1; however, mechanistic connections of this event to apoptosis remain obscure. In this study, we identified the antiapoptotic protein YAP, a core component of the Hippo signaling pathway implicated in tumorigenesis, as a critical linker coupling Cdk1 activation to apoptosis in the antitubulin drug response. Antitubulin drugs activated Cdk1, which directly phosphorylated YAP on five sites independent of the Hippo pathway. Mutations in these phosphorylation sites on YAP relieved its ability to block antitubulin drug-induced apoptosis, further suggesting that YAP was inactivated by Cdk1 phosphorylation. Notably, we found that YAP was not phosphorylated and inactivated after antitubulin drug treatment in taxol-resistant cancer cells. Our findings suggest YAP and its phosphorylation status as candidate prognostic markers in predicting antitubulin drug response in patients.

Wiegmans AP, Al-Ejeh F, Chee N, et al.
Rad51 supports triple negative breast cancer metastasis.
Oncotarget. 2014; 5(10):3261-72 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
In contrast to extensive studies on familial breast cancer, it is currently unclear whether defects in DNA double strand break (DSB) repair genes play a role in sporadic breast cancer development and progression. We performed analysis of immunohistochemistry in an independent cohort of 235 were sporadic breast tumours. This analysis suggested that RAD51 expression is increased during breast cancer progression and metastasis and an oncogenic role for RAD51 when deregulated. Subsequent knockdown of RAD51 repressed cancer cell migration in vitro and reduced primary tumor growth in a syngeneic mouse model in vivo. Loss of RAD51 also inhibited associated metastasis not only in syngeneic mice but human xenografts and changed the metastatic gene expression profile of cancer cells, consistent with inhibition of distant metastasis. This demonstrates for the first time a new function of RAD51 that may underlie the proclivity of patients with RAD51 overexpression to develop distant metastasis. RAD51 is a potential biomarker and attractive drug target for metastatic triple negative breast cancer, with the capability to extend the survival of patients, which is less than 6 months.

Lorenzetto E, Brenca M, Boeri M, et al.
YAP1 acts as oncogenic target of 11q22 amplification in multiple cancer subtypes.
Oncotarget. 2014; 5(9):2608-21 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
The transcriptional coactivator YAP1 is a critical effector of the human Salvador-Warts-Hippo pathway. Literature data report apparently discrepant results on the carcinogenic role of YAP1, which acts either as oncogene or as tumor suppressor in different in vitro and in vivo models. Furthermore, genomic amplification events of 11q22 locus encompassing YAP1 gene have been detected in multiple tumor types but there is limited direct evidence about the oncogenic role of endogenous YAP1 within in the amplicon. We screened a panel of human tumor samples and cancer cell lines and identified that the YAP1 amplification event is actually present in up to 23% of the cases. We exploited EKVX (lung cancer), CaSki (cervical cancer) and RO82 (thyroid cancer) cell lines harboring both genomic YAP1 amplification and YAP1 protein overexpression, in order to study the effects of downregulation of endogenous YAP1 by RNA-interference strategies. Class comparison analysis of gene expression profiling data identified 707 statistically significantly modulated genes (multivariable global test p-value = 0.002) that were functionally annotated for cell proliferation and cellular movement ontologies. Mechanistic studies of the identified perturbed pathways revealed that YAP1 silencing significantly decreased cell proliferation and cell cycle perturbation associated with upregulation of p21 and p27 cell-cycle inhibitors, reduced cell migration (p<0.048) and anchorage-independent growth (p<0.02). In CaSki cell line, YAP1 silencing induced significantly increased sensitivity and cell-death response to cisplatin treatment (p=0.011) as well as reduction of in-vivo tumorigenic potential (p=0.027). Overall, these results establish that YAP1 is a direct oncogenic target of the 11q22 amplicon in previously unreported cancer types and support the relevance of such genetic aberration in carcinogenesis in a fraction of multiple tumor types.

Zhang W, Nandakumar N, Shi Y, et al.
Downstream of mutant KRAS, the transcription regulator YAP is essential for neoplastic progression to pancreatic ductal adenocarcinoma.
Sci Signal. 2014; 7(324):ra42 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor survival rates and frequently carries oncogenic KRAS mutation. However, KRAS has thus far not been a viable therapeutic target. We found that the abundance of YAP mRNA, which encodes Yes-associated protein (YAP), a protein regulated by the Hippo pathway during tissue development and homeostasis, was increased in human PDAC tissue compared with that in normal pancreatic epithelia. In genetically engineered Kras(G12D) and Kras(G12D):Trp53(R172H) mouse models, pancreas-specific deletion of Yap halted the progression of early neoplastic lesions to PDAC without affecting normal pancreatic development and endocrine function. Although Yap was dispensable for acinar to ductal metaplasia (ADM), an initial step in the progression to PDAC, Yap was critically required for the proliferation of mutant Kras or Kras:Trp53 neoplastic pancreatic ductal cells in culture and for their growth and progression to invasive PDAC in mice. Yap functioned as a critical transcriptional switch downstream of the oncogenic KRAS-mitogen-activated protein kinase (MAPK) pathway, promoting the expression of genes encoding secretory factors that cumulatively sustained neoplastic proliferation, a tumorigenic stromal response in the tumor microenvironment, and PDAC progression in Kras and Kras:Trp53 mutant pancreas tissue. Together, our findings identified Yap as a critical oncogenic KRAS effector and a promising therapeutic target for PDAC and possibly other types of KRAS-mutant cancers.

Berg T, Thoene S, Yap D, et al.
A transgenic mouse model demonstrating the oncogenic role of mutations in the polycomb-group gene EZH2 in lymphomagenesis.
Blood. 2014; 123(25):3914-24 [PubMed] Related Publications
The histone methyltransferase EZH2 is frequently mutated in germinal center-derived diffuse large B-cell lymphoma and follicular lymphoma. To further characterize these EZH2 mutations in lymphomagenesis, we generated a mouse line where EZH2(Y641F) is expressed from a lymphocyte-specific promoter. Spleen cells isolated from the transgenic mice displayed a global increase in trimethylated H3K27, but the mice did not show an increased tendency to develop lymphoma. As EZH2 mutations often coincide with other mutations in lymphoma, we combined the expression of EZH2(Y641F) by crossing these transgenic mice with Eµ-Myc transgenic mice. We observed a dramatic acceleration of lymphoma development in this combination model of Myc and EZH2(Y641F). The lymphomas show histologic features of high-grade disease with a shift toward a more mature B-cell phenotype, increased cycling and gene expression, and epigenetic changes involving important pathways in B-cell regulation and function. Furthermore, they initiate disease in secondary recipients. In summary, EZH2(Y641F) can collaborate with Myc to accelerate lymphomagenesis demonstrating a cooperative role of EZH2 mutations in oncogenesis. This murine lymphoma model provides a new tool to study global changes in the epigenome caused by this frequent mutation and a promising model system for testing novel treatments.

Mitamura T, Watari H, Wang L, et al.
microRNA 31 functions as an endometrial cancer oncogene by suppressing Hippo tumor suppressor pathway.
Mol Cancer. 2014; 13:97 [PubMed] Article available free on PMC after 01/09/2015 Related Publications
BACKGROUND: We aimed to investigate whether MIR31 is an oncogene in human endometrial cancer and identify the target molecules associated with the malignant phenotype.
METHODS: We investigated the growth potentials of MIR31-overexpressing HEC-50B cells in vitro and in vivo. In order to identify the target molecule of MIR31, a luciferase reporter assay was performed, and the corresponding downstream signaling pathway was examined using immunohistochemistry of human endometrial cancer tissues. We also investigated the MIR31 expression in 34 patients according to the postoperative risk of recurrence.
RESULTS: The overexpression of MIR31 significantly promoted anchorage-independent growth in vitro and significantly increased the tumor forming potential in vivo. MIR31 significantly suppressed the luciferase activity of mRNA combined with the LATS2 3'-UTR and consequently promoted the translocation of YAP1, a key molecule in the Hippo pathway, into the nucleus. Meanwhile, the nuclear localization of YAP1 increased the transcription of CCND1. Furthermore, the expression levels of MIR31 were significantly increased (10.7-fold) in the patients (n = 27) with a high risk of recurrence compared to that observed in the low-risk patients (n = 7), and this higher expression correlated with a poor survival.
CONCLUSIONS: MIR31 functions as an oncogene in endometrial cancer by repressing the Hippo pathway. MIR31 is a potential new molecular marker for predicting the risk of recurrence and prognosis of endometrial cancer.

Visuvanathan S, Chong PP, Yap YY, et al.
Distribution and haplotype associations of XPD Lys751Gln, XRCC1 Arg280His and XRCC1 Arg399Gln polymorphisms with nasopharyngeal carcinoma in the Malaysian population.
Asian Pac J Cancer Prev. 2014; 15(6):2747-51 [PubMed] Related Publications
BACKGROUND: DNA repair pathways play a crucial role in maintaining the human genome. Previous studies associated DNA repair gene polymorphisms (XPD Lys751Gln, XRCC1 Arg280His and XRCC1 Arg399Gln) with nasopharyngeal carcinoma. These non-synonymous polymorphisms may alter DNA repair capacity and thus increase or decrease susceptibility. The present study aimed to determine the genotype distribution of XPD codon 751, XRCC1 codon 280 and codon 399 polymorphisms and haplotype associations among NPC cases and controls in the Malaysian population.
MATERIALS AND METHODS: We selected 157 NPC cases and 136 controls from two hospitals in Kuala Lumpur, Malaysia for this study. The polymorphisms studied were genotyped by PCR-RFLP assay and allele and genotype frequencies, haplotype and linkage disequilibrium were determined using SNPstat software.
RESULTS: For the XPD Lys751Gln polymorphism, the frequency of the Lys allele was higher in cases than in controls (94.5% versus 85.0%). For the XRCC1 Arg280His polymorphism, the frequency of Arg allele was 90.0% and 89.0% in cases and controls, respectively and for XRCC1 Arg399Gln the frequency of the Arg allele was 72.0% and 72.8% in cases and controls respectively. All three polymorphisms were in linkage disequilibrium. The odds ratio from haplotype analysis for these three polymorphisms and their association with NPC was 1.93 (95%CI: 0.90-4.16) for haplotype CGC vs AGC allele combinations. The global haplotype association with NPC gave a p-value of 0.054.
CONCLUSIONS: Our study provides an estimate of allele and genotype frequencies of XRCC1Arg280His, XRCC1 Arg399Gln and XPD Lys751Gln polymorphisms in the Malaysian population and showed no association with nasopharyngeal cancer.

André F, O'Regan R, Ozguroglu M, et al.
Everolimus for women with trastuzumab-resistant, HER2-positive, advanced breast cancer (BOLERO-3): a randomised, double-blind, placebo-controlled phase 3 trial.
Lancet Oncol. 2014; 15(6):580-91 [PubMed] Related Publications
BACKGROUND: Disease progression in patients with HER2-positive breast cancer receiving trastuzumab might be associated with activation of the PI3K/Akt/mTOR intracellular signalling pathway. We aimed to assess whether the addition of the mTOR inhibitor everolimus to trastuzumab might restore sensitivity to trastuzumab.
METHODS: In this randomised, double-blind, placebo-controlled, phase 3 trial, we recruited women with HER2-positive, trastuzumab-resistant, advanced breast carcinoma who had previously received taxane therapy. Eligible patients were randomly assigned (1:1) using a central patient screening and randomisation system to daily everolimus (5 mg/day) plus weekly trastuzumab (2 mg/kg) and vinorelbine (25 mg/m(2)) or to placebo plus trastuzumab plus vinorelbine, in 3-week cycles, stratified by previous lapatinib use. The primary endpoint was progression-free survival (PFS) by local assessment in the intention-to-treat population. We report the final analysis for PFS; overall survival follow-up is still in progress. This trial is registered with ClinicalTrials.gov, number NCT01007942.
FINDINGS: Between Oct 26, 2009, and May 23, 2012, 569 patients were randomly assigned to everolimus (n=284) or placebo (n=285). Median follow-up at the time of analysis was 20.2 months (IQR 15.0-27.1). Median PFS was 7.00 months (95% CI 6.74-8.18) with everolimus and 5.78 months (5.49-6.90) with placebo (hazard ratio 0.78 [95% CI 0.65-0.95]; p=0.0067). The most common grade 3-4 adverse events were neutropenia (204 [73%] of 280 patients in the everolimus group vs 175 [62%] of 282 patients in the placebo group), leucopenia (106 [38%] vs 82 [29%]), anaemia (53 [19%] vs 17 [6%]), febrile neutropenia (44 [16%] vs ten [4%]), stomatitis (37 [13%] vs four [1%]), and fatigue (34 [12%] vs 11 [4%]). Serious adverse events were reported in 117 (42%) patients in the everolimus group and 55 (20%) in the placebo group; two on-treatment deaths due to adverse events occurred in each group.
INTERPRETATION: The addition of everolimus to trastuzumab plus vinorelbine significantly prolongs PFS in patients with trastuzumab-resistant and taxane-pretreated, HER2-positive, advanced breast cancer. The clinical benefit should be considered in the context of the adverse event profile in this population.

Machado-Neto JA, Lazarini M, Favaro P, et al.
ANKHD1, a novel component of the Hippo signaling pathway, promotes YAP1 activation and cell cycle progression in prostate cancer cells.
Exp Cell Res. 2014; 324(2):137-45 [PubMed] Related Publications
ANKHD1 is a multiple ankyrin repeat containing protein, recently identified as a novel member of the Hippo signaling pathway. The present study aimed to investigate the role of ANKHD1 in DU145 and LNCaP prostate cancer cells. ANKHD1 and YAP1 were found to be highly expressed in prostate cancer cells, and ANKHD1 silencing decreased cell growth, delayed cell cycle progression at the S phase, and reduced tumor xenograft growth. Moreover, ANKHD1 knockdown downregulated YAP1 expression and activation, and reduced the expression of CCNA2, a YAP1 target gene. These findings indicate that ANKHD1 is a positive regulator of YAP1 and promotes cell growth and cell cycle progression through Cyclin A upregulation.

Welt CK, Duran JM
Genetics of polycystic ovary syndrome.
Semin Reprod Med. 2014; 32(3):177-82 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
The etiology of polycystic ovary syndrome (PCOS) has been difficult to determine because its features are heterogeneous, and its origin may also be heterogeneous. Twin studies suggest that its etiology is strongly heritable and genetic approaches are rapidly uncovering new regions of the genome that appear to confer risk for PCOS. Recent genome-wide association studies in Han Chinese women with PCOS demonstrate 11 genetic loci that are associated with PCOS. The variants identified are in regions that contain genes important for gonadotropin action, genes that are associated with risk for type 2 diabetes, and other genes in which the relationship to PCOS is not yet clear. Replication studies have demonstrated that variants at several of these loci also confer risk for PCOS in women of European ethnicity. The strongest loci in Europeans contain genes for DENND1A and THADA, with additional associations in loci containing the LHCGR and FSHR, YAP1 and RAB5/SUOX. The next steps in uncovering the pathophysiology borne out by these loci and variants will include mapping to determine the causal variant and gene, phenotype studies to determine whether these regions are associated with particular features of PCOS and functional studies of the causal variant to determine the direct cause of PCOS based on the underlying genetics. The next years will be very exciting times as groups from around the world come together to further elucidate the genetic origins of PCOS.

Lin XY, Zhang XP, Wu JH, et al.
Expression of LATS1 contributes to good prognosis and can negatively regulate YAP oncoprotein in non-small-cell lung cancer.
Tumour Biol. 2014; 35(7):6435-43 [PubMed] Related Publications
Large tumor suppressor (LATS) is a Ser/Thr kinase originally isolated from Drosophila. Recent studies demonstrate that LATS is an important member of the Hippo pathway which can regulate organ size and cell proliferation. However, little is known about the expression and clinical significance of LATS in lung cancer. In this study, we aimed to assess the clinical significance and biological functions of LATS1 in non-small-cell lung cancer (NSCLC). We investigated the expression of LATS1 in 136 cases of NSCLC tissue and 30 cases of normal lung tissue by immunohistochemical staining. The results confirmed that LATS1 expression was higher in normal lung tissues, but significantly lower in NSCLC tissues. Moreover, the expression of LATS1 in NSCLC was significantly correlated with p-TNM stage (p = 0.038) and lymph node metastasis (p = 0.014). Importantly, the loss of LATS1 expression was associated with short overall survival. Further study in NSCLC cell lines in which LATS1 was either overexpressed or depleted confirmed that LATS1 markedly inhibited cell proliferation and invasion and could regulate the nuclear location of yes-associated protein (YAP). These results indicate that LATS1 may play an important role in NSCLC, and may serve as a novel therapeutic target of NSCLC.

Hiemer SE, Szymaniak AD, Varelas X
The transcriptional regulators TAZ and YAP direct transforming growth factor β-induced tumorigenic phenotypes in breast cancer cells.
J Biol Chem. 2014; 289(19):13461-74 [PubMed] Article available free on PMC after 09/05/2015 Related Publications
Uncontrolled transforming growth factor-β (TGFβ) signaling promotes aggressive metastatic properties in late-stage breast cancers. However, how TGFβ-mediated cues are directed to induce tumorigenic events is poorly understood, particularly given that TGFβ has clear tumor suppressing activity in other contexts. Here, we demonstrate that the transcriptional regulators TAZ and YAP (TAZ/YAP), key effectors of the Hippo pathway, are necessary to promote and maintain TGFβ-induced tumorigenic phenotypes in breast cancer cells. Interactions between TAZ/YAP, TGFβ-activated SMAD2/3, and TEAD transcription factors reveal convergent roles for these factors in the nucleus. Genome-wide expression analyses indicate that TAZ/YAP, TEADs, and TGFβ-induced signals coordinate a specific pro-tumorigenic transcriptional program. Importantly, genes cooperatively regulated by TAZ/YAP, TEAD, and TGFβ, such as the novel targets NEGR1 and UCA1, are necessary for maintaining tumorigenic activity in metastatic breast cancer cells. Nuclear TAZ/YAP also cooperate with TGFβ signaling to promote phenotypic and transcriptional changes in nontumorigenic cells to overcome TGFβ-repressive effects. Our work thus identifies cross-talk between nuclear TAZ/YAP and TGFβ signaling in breast cancer cells, revealing novel insight into late-stage disease-driving mechanisms.

Yu FX, Guan KL
Transcription and processing: multilayer controls of RNA biogenesis by the Hippo pathway.
EMBO J. 2014; 33(9):942-4 [PubMed] Article available free on PMC after 02/05/2015 Related Publications
The Hippo pathway plays a critical role in organ size control and tumorigenesis. YAP (and also its homologue TAZ) is a transcription co-activator that mediates the biological functions of the Hippo pathway. YAP activity is inhibited upon phosphorylation by the Lats kinases (reviewed in Yu & Guan, 2013). In a recent study in Cell, Mori et al (2014) uncover a new function of YAP in global microRNA (miRNA) biogenesis by the modulation of the Microprocessor machinery. The results also suggest that this novel YAP function may contribute to cell growth control and tumorigenesis.

Roth A, Khattra J, Yap D, et al.
PyClone: statistical inference of clonal population structure in cancer.
Nat Methods. 2014; 11(4):396-8 [PubMed] Related Publications
We introduce PyClone, a statistical model for inference of clonal population structures in cancers. PyClone is a Bayesian clustering method for grouping sets of deeply sequenced somatic mutations into putative clonal clusters while estimating their cellular prevalences and accounting for allelic imbalances introduced by segmental copy-number changes and normal-cell contamination. Single-cell sequencing validation demonstrates PyClone's accuracy.

Yap LF, Ahmad M, Zabidi MM, et al.
Oncogenic effects of WNT5A in Epstein-Barr virus‑associated nasopharyngeal carcinoma.
Int J Oncol. 2014; 44(5):1774-80 [PubMed] Related Publications
The molecular events that drive the progression of Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) are still to be elucidated. Here, we report for the first time the pathogenic significance of an NPC-associated gene, wingless-type MMTV integration site family, member 5A (WNT5A) and the contribution of EBV to its expression. WNT5A is a representative Wnt protein that activates non-canonical Wnt signalling. With regard to its role in carcinogenesis, there is conflicting evidence as to whether WNT5A has a tumour-promoting or tumour-suppressive role. We show that WNT5A is upregulated in primary NPC tissue samples. We also demonstrate that WNT5A expression was dramatically increased in NPC cell lines expressing the EBV-encoded LMP2A gene, suggesting that this EBV-encoded latent gene is responsible for upregulating WNT5A in NPC. In addition, in vitro WNT5A overexpression promotes the proliferation, migration and invasion of NPC cells. Our results not only reveal pro-tumorigenic effects of WNT5A in NPC but also suggest that WNT5A could be an important therapeutic target in patients with EBV-associated disease.

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