Role Of Yes-associated Protein Research Articles

TEAD family transcription factors in development and disease.

The balance between stem cell potency and lineage specification entails the integration of both extrinsic and intrinsic cues, which ultimately influence gene expression through the activity of transcription factors. One example of this is provided by the Hippo signalling pathway, which plays a central role in regulating organ size during development. Hippo pathway activity is mediated by the transcriptional co-factors Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), which interact with TEA domain (TEAD) proteins to regulate gene expression. Although the roles of YAP and TAZ have been intensively studied, the roles played by TEAD proteins are less well understood. Recent studies have begun to address this, revealing that TEADs regulate the balance between progenitor self-renewal and differentiation throughout various stages of development. Furthermore, it is becoming apparent that TEAD proteins interact with other co-factors that influence stem cell biology. This Primer provides an overview of the role of TEAD proteins during development, focusing on their role in Hippo signalling as well as within other developmental, homeostatic and disease contexts.

Role of Yes-associated Protein-1 in Gastrointestinal Cancers and Hepatocellular Carcinoma

Yes-associated protein-1 (YAP1) is a potent transcriptional co-activator and functions as an important downstream effector of the Hippo signaling pathway, which is key to regulating cell proliferation, apoptosis, and organ growth. YAP1 has been implicated as an oncogene for various human cancers including gastrointestinal cancers and hepatocellular carcinoma (HCC). YAP1 promotes tumorigenesis and cancer progression by multiple mechanisms, such as by promoting malignant phenotypes, expanding cancer stem cells, and inducing epithelial-mesenchymal transition. YAP1 overexpression or its activated forms are associated with advanced pathological grades and poor prognosis of cancer, and therefore targeting YAP1 may open a fertile avenue for cancer therapy. In this review, we summarize the recent evidence regarding the role of YAP1 in the carcinogenesis of gastrointestinal cancers and HCC.

YAP1 transcription factor expression to define subsets of cancers with T-cell inflamed phenotype in a pan-tumor analysis across 33 tumor types.

2610 Background: Immune checkpoint blockade (ICB) has become an established treatment option for the majority of solid tumors. PD-L1 expression, tumor mutation burden (TMB) and mismatch repair (MMR) deficiency are established but suboptimal predictive markers to select patients for ICB therapy. The identification of better predictive biomarkers to complement existing biomarkers is an area of need. We previously identified Yes Associated Protein 1 (YAP1) gene expression as a marker of inflamed tumor phenotype in small cell lung cancer. We sought to elucidate the role of YAP1 as a tumor agnostic biomarker of inflamed tumor phenotype. Methods: We obtained the publicly available TCGA normalized RSEM expression data (version dated September 29, 2019) from the GDC legacy archive (https://portal.gdc.cancer.gov/legacy-archive) for this analysis. We used the shinySISPA method ( https://bbisr.shinyapps.winship.emory.edu/shinySISPA/ ) to classify the primary tumor samples into YAP1 high or low on the basis of the normalized expression profile for YAP1 gene. The T-cell–inflamed gene expression profile score for each sample was calculated as weighted sum of the normalized expression values of the 18 genes ( PSMB10, HLA-DQA1, HLA-DRB1, CMKLR1, HLA-E, NKG7, CD8A, CCL5, CXCL9, CD27, CXCR6, IDO1, STAT1, TIGIT, LAG3, CD274, PDCD1LG2, CD276) as originally published in the Patent filed under “WO201609437” and validated as a predictor of clinical efficacy in patients treated with anti PD1 immunotherapy drug, pembrolizumab. Results: A total of 11283 samples from 33 different histologic tumor types contained in the TCGA database were included in this analysis. A small but meaningful subset of cases 271 (2%) were classified as YAP1 high with a wide range in proportion of YAP1 high tumors of 0.67% to 12.09% across the 33 histologic tumor types. Adrenocortical, cholangiocarcinoma, chromophobe RCC, DLBCL, and mesothelioma had a high rate of YAP1 high tumors (> 10% of cases). Overall trend showed a higher median interferon gamma GEP score in YAP1 high versus YAP1 low tumors with a GEP score of 11.2 vs. 10.7 respectively. A minority of histologic tumor subtypes (HNSCC, clear cell RCC, sarcoma, uterine carcinosarcoma, testicular GCT, melanoma, mesothelioma and ovarian cancer) showed a reverse trend of lower GEP score in association with YAP1 high status. Ongoing validation of these findings in an independent cohort of clinical samples and correlation of YAP1 status with other predictive biomarkers (TMB, PD-L1 and MSS status) will be presented at the meeting. Conclusions: YAP1 is highly expressed in a small but meaningful subsets of cancers and is associated with the inflamed phenotype in the majority of cancers. YAP1 expression is most common in rarer tumor types and in histologic types where currently available biomarkers have not been shown to predict the benefit of ICB.

The role of YAP in the control of the metastatic potential of oral cancer.

The Yes-associated protein (YAP) is a downstream effector of the Hippo pathway and acts as a key transcription co-factor to regulate cell migration, proliferation, and survival. The Hippo pathway is evolutionarily conserved and controls tissue growth and organ size. Dysregulation and heterogeneity of this pathway are found in cancers, including oral squamous cell carcinoma (OSCC), leading to overexpression of YAP and its regulated proliferation machinery. The activity of YAP is associated with its nuclear expression and is negatively regulated by the Hippo kinase-mediated phosphorylation resulting in an induction of its cytoplasmic translocation. This review focuses on the role of YAP in OSCC in the context of cancer metastatic potential and highlights the latest findings about the heterogeneity of YAP expression and its nuclear transcription activity in oral cancer cell lines. The review also discusses the potential target of YAP in oral cancer therapy and the recent finding of the unprecedented role of the desmosomal cadherin desmoglein-3 (DSG3) in regulating Hippo-YAP signaling.

Role of YAP-related T cell imbalance and epidermal keratinocyte dysfunction in the pathogenesis of atopic dermatitis

BackgroundAtopic dermatitis (AD) is characterized by impaired skin barrier function and immune system dysfunction. The expression and role of Yes-associated protein (YAP) in AD are unclear. ObjectiveTo characterize the role of the YAP in T cell imbalance and epidermal keratinocyte dysfunction in the pathogenesis of AD. MethodsWe included 35 patients with AD (21 acute and 14 chronic). An AD mouse model was constructed using 2,4-dinitrofluorobenzene, and AD-like inflammatory cell model was constructed using TNF-α/IFN-γ-activated HaCaT cells. The proportion of Th1/Th2/Th17/Treg cells was detected using flow cytometry. After mononuclear cells were obtained from human peripheral blood or mouse spleen and induced to differentiate into different T cell subsets, YAP mRNA and protein expression were analyzed. Up-regulation of YAP was induced by lentivirus and down-regulation of YAP was induced by its specific inhibitor verteporfin (VP). The expression of YAP in skin lesions and infiltrating T cell subsets was detected using immunohistochemistry and double immunofluorescence staining, respectively. ResultsWe found differing degrees of Th1/Th2/Th17/Treg imbalance in acute and chronic AD. YAP expression was downregulated in Treg cells and upregulated in Th17 cells; YAP expression was downregulated in the AD epidermis. After YAP overexpression, the proportion of both Th17 and the Treg cells differentiated from mouse spleen mononuclear cells increased. There was an opposite trend after YAP inhibition. The proliferation and migration decreased and apoptosis increased after YAP inhibition in HaCaT cells. ConclusionChange of YAP expression may cause T cell imbalance and hamper the healing of the epidermis in AD.

YAP accelerates vascular senescence via blocking autophagic flux and activating mTOR.

Yes‐associated protein (YAP), a major effector of the Hippo signalling pathway, is widely implicated in vascular pathophysiology processes. Here, we identify a new role of YAP in the regulation of vascular senescence. The inhibition or deficiency and overexpression of YAP were performed in human umbilical vein endothelial cells (HUVECs) and isolated vascular tissues. Cellular and vascular senescence was assessed by analysis of the senescence‐associated β‐galactosidase (SA‐β‐gal) and expression of senescence markers P16, P21, P53, TERT and TRF1. We found that YAP was highly expressed in old vascular tissues, inhibition and knockdown of YAP decreased senescence, while overexpression of YAP increased the senescence in both HUVECs and vascular tissues. In addition, autophagic flux blockage and mTOR pathway activation were observed during YAP‐induced HUVECs and vascular senescence, which could be relieved by the inhibition and knockdown of YAP. Moreover, YAP‐promoted cellular and vascular senescence could be relieved by mTOR inhibition. Collectively, our findings indicate that YAP may serve as a potential therapeutic target for ageing‐associated cardiovascular disease.

Yes-associated protein-1 may serve as a diagnostic marker and therapeutic target for residual/recurrent hepatocellular carcinoma post-transarterial chemoembolization

Background and aimThe transcriptional co-activator Yes-associated protein-1 (YAP1) has been implicated as an oncogene and is overexpressed in different kinds of human cancers, especially hepatocellular carcinoma (HCC). However, the role of YAP1 has not been reported in residual/recurrent HCC after transarterial chemoembolization (TACE). Our aim is to determine whether YAP1 is overexpressed in the residual/recurrent HCC after TACE. MethodsA total of 105 tumor tissues from 71 patients including 30 cases of primary HCC without prior treatment, 35 cases of residual/recurrent HCC post TACE, and 6 cases of hepatoblastoma were included in the immunohistochemical study. YAP1 immunoreactivity was blindly scored as 0, 1+, 2+ or 3+ in density and percentages of positive cells. ResultsAbout 33.3% (10/30) of primary HCC without prior treatment showed 2+ of YAP1 immunoreactivity. While 82.8% (29/35) of residual/recurrent HCCs after TACE treatment displayed 2–3+ of YAP1 immunoreactivity, which was significantly higher compared to primary HCC without prior treatment (P = 0.0002). YAP1 immunoreactivity was moderately to strongly positive (2–3+) in 100% of the hepatoblastoma, particularly in the embryonal components (3+ in 100% cases). ConclusionsYAP1 is significantly upregulated in the residual/recurrent HCCs post TACE treatment, suggesting that YAP1 may serve as a sensitive diagnostic marker and a treatment target for residual/recurrent HCC post TACE.

Isorhapontigenin protects against doxorubicin-induced cardiotoxicity via increasing YAP1 expression

As an effective anticancer drug, the clinical limitation of doxorubicin (Dox) is the time- and dose-dependent cardiotoxicity. Yes-associated protein 1 (YAP1) interacts with transcription factor TEA domain 1 (TEAD1) and plays an important role in cell proliferation and survival. However, the role of YAP1 in Dox-induced cardiomyopathy has not been reported. In this study, the expression of YAP1 was reduced in clinical human failing hearts with dilated cardiomyopathy and Dox-induced in vivo and in vitro cardiotoxic model. Ectopic expression of Yap1 significantly blocked Dox-induced cardiomyocytes apoptosis in TEAD1 dependent manner. Isorhapontigenin (Isor) is a new derivative of stilbene and responsible for a wide range of biological processes. Here, we found that Isor effectively relieved Dox-induced cardiomyocytes apoptosis in a dose-dependent manner in vitro. Administration with Isor (30 mg/kg/day, intraperitoneally, 3 weeks) significantly protected against Dox-induced cardiotoxicity in mice. Interestingly, Isor increased Dox-caused repression in YAP1 and the expression of its target genes in vivo and in vitro. Knockout or inhibition of Yap1 blocked the protective effects of Isor on Dox-induced cardiotoxicity. In conclusion, YAP1 may be a novel target for Dox-induced cardiotoxicity and Isor might be a new compound to fight against Dox-induced cardiotoxicity by increasing YAP1 expression.

Yes-Associated Protein 1: Role and Treatment Prospects in Orthopedic Degenerative Diseases.

The Hippo/yes-associated protein 1 signaling pathway is an evolutionarily conserved signaling pathway. This signaling pathway is primarily involved in the regulation of stem cell self-renewal, organ size and tissue regeneration by regulating cell proliferation, differentiation and apoptosis. It plays an important role in embryonic development and tissue organ formation. Yes-associated protein 1 (YAP1) is a key transcription factor in the Hippo signaling pathway and is negatively regulated by this pathway. Changes in YAP1 expression levels affect the occurrence and development of a variety of tumors, but the specific mechanism associated with this phenomenon has not been thoroughly studied. Recently, several studies have described the role of YAP1 in osteoarthritis (OA). Indeed, YAP1 is involved in orthopedic degenerative diseases such as osteoporosis (OP) in addition to OA. In this review, we will summarize the significance of YAP1 in orthopedic degenerative diseases and discuss the potential of the targeted modulation of YAP1 for the treatment of these diseases.

Yes-Associated Protein Contributes to Cell Proliferation and Migration of Gastric Cancer via Activation of Gli1.

ObjectiveIn the present study, we aimed to explore the potential oncogenic property and the internal mechanism of yes-associated protein (YAP) in gastric cancer (GC).Materials and MethodsYAP protein levels were evaluated in human GC tissues and paired normal tissues using immunohistochemistry (IHC). The role of YAP in regulating GC cell proliferation and migration was verified by genetic manipulation in vitro. Western blot analysis was used to determine the molecular signaling to explain the mechanism of the observed YAP effects in GC.ResultsNuclear YAP protein expression was upregulated in GC tissues, and high nuclear YAP level was significantly correlated with lymph node metastasis (LNM) and tumor node metastasis (TNM) stage in patients suffered from GC. YAP knockdown inhibited GC cell proliferation, migration and epithelial–mesenchymal transition (EMT) progress in vitro, whereas YAP elevation did the opposite. YAP regulated glioma-associated oncogene-1 (Gli1) expression independent of smoothened homolog (SMO). YAP modulated protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway in GC cells.ConclusionYAP enhanced GC cell proliferation and migration potentially via its regulation of Gli1 expression through the non-classical Hedgehog pathway, indicating suppression of YAP/Gli1 signaling axis may highlight a new entry point for combination therapy of GC.

Phosphorylation of Yes-associated protein impairs trophoblast invasion and migration: implications for the pathogenesis of fetal growth restriction†.

Fetal growth restriction (FGR) is a condition in which a newborn fails to achieve his or her prospective hereditary growth potential. This condition is associated with high newborn mortality, second only to that associated with premature birth. FGR is associated with maternal, fetal, and placental abnormalities. Although the placenta is considered to be an important organ for supplying nutrition for fetal growth, research on FGR is limited, and treatment through the placenta remains challenging, as neither proper uterine intervention nor its pathogenesis have been fully elucidated. Yes-associated protein (YAP), as the effector of the Hippo pathway, is widely known to regulate organ growth and cancer development. Therefore, the correlation of the placenta and YAP was investigated to elucidate the pathogenic mechanism of FGR. Placental samples from humans and mice were collected for histological and biomechanical analysis. After investigating the location and role of YAP in the placenta by immunohistochemistry, we observed that YAP and cytokeratin 7 have corresponding locations in human and mouse placentas. Moreover, phosphorylated YAP (p-YAP) was upregulated in FGR and gradually increased as gestational age increased during pregnancy. Cell function experiments and mRNA-Seq demonstrated impaired YAP activity mediated by extracellular signal-regulated kinase inhibition. Established FGR-like mice also recapitulated a number of the features of human FGR. The results of this study may help to elucidate the association of FGR development with YAP and provide an intrauterine target that may be helpful in alleviating placental dysfunction.

Abstract A39: The role of YAP in regulating glycogen metabolism in pancreatic cancer

Abstract Pancreatic ductal adenocarcinoma (PDAC) is driven largely by oncogenic KRAS mutations, making KRAS and its downstream effectors, in theory, ideal candidates for therapeutic intervention. Unfortunately, attempts to directly inhibit KRAS or its effectors have either been unsuccessful or ineffective and, as a result, there is much interest in identifying novel downstream effectors of oncogenic KRAS signaling. Yes-associated protein (YAP) has been shown to be an essential mediator of oncogenic KRAS signaling during PDAC progression as well as a marker for poor prognosis in PDAC patients. YAP is required for tumor recurrence and is able to compensate for loss of oncogenic KRAS in several cancer types, suggesting interplay between these pathways. YAP is a transcriptional co-activator that partners with transcription factors to control organ size, and upregulation of YAP is frequently observed in human cancers. Downstream target genes of YAP include cyclins and growth factors involved in proliferation, but YAP also induces stem cell properties, drug resistance, and metastasis, suggesting the presence of additional targets that affect various cellular processes. As KRAS is a major regulator of cellular metabolism and can upregulate scavenging pathways, such as autophagy and macropinocytosis, we hypothesize that YAP may also play a role in metabolic reprogramming of pancreatic cancers based on its importance in tumor initiation and progression. Our data demonstrate that YAP depletion in PDAC cells leads to dysregulated glycogen metabolism through regulation of uridine diphosphate glucose (UDP-Glc), the direct glucosyl donor for glycogen synthesis. UDP-Glc is synthesized from glucose-1-phosphate and uridine triphosphate (UTP) by UDP-Glc pyrophorphorylase 2 (UGP2), the sole enzyme responsible for this reaction in mammalian cells. YAP-depleted cells showed corresponding decrease of UGP2 mRNA and protein levels in a panel of PDAC cell lines. TCGA provisional dataset analysis showed a statistically significant tendency towards co-occurrence (p<0.001) between YAP and UGP2 mRNA levels in PDAC patients, and immunohistochemistry of tissues samples showed high correlation between YAP and UGP2 expression patterns, suggesting this regulation also exists in PDAC patients. Cells depleted of UGP2 showed a marked decrease of cell growth in 2D and 3D cultures, suggesting that UGP2 plays an important role in PDAC cell survival and proliferation. Interestingly, cells expressing oncogenic KRAS or its direct downstream effector, BRAF, have increased UGP2 expression and glycogen levels that are YAP-dependent. This suggests that glycogen metabolism may be an integral part of YAP-dependent KRAS signaling and that this pathway has an important function in PDAC cells. This is a novel role of YAP that has not been previously reported, and here we seek to understand the mechanism of how YAP regulates this pathway and its function in PDAC cells. Citation Format: Sung Eun (Monica) Kim, Jacqueline Galeas, Frank McCormick. The role of YAP in regulating glycogen metabolism in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr A39.

YAP Involves in Reduced Anabolic Response to Functional Overload in Lewis Lung Carcinoma‐bearing Mice

Cancer‐associated weight loss, also known as cachexia, is connected to poor prognosis, reduced response to chemotherapy, and impaired patient quality of life. While resistance exercise/muscle contraction is a promising therapy, anabolic resistance, the suppressed ability to induce protein synthesis, is present and can’t be solely elucidated by the change of mTOR signaling. Yes‐associated protein (YAP) is a downstream effector of Hippo signaling and is known to control skeletal muscle size in response to mechanical stimulus. However, the role of YAP on anabolic resistance in cancer cachexia needs to be clarified. The purpose of this study was to determine whether the state of YAP activity after functional overload is altered in cachectic mice. Approximately three‐month‐old male C57BL6 mice were divided into two groups: Control group with PBS (100 μl) injection (Con, n=5) and tumor‐implantation group with Lewis lung Carcinoma (LLC) cells injection (2×105 cells in 100 μl PBS, LLC, n=5). Injection was made at the right flank under anesthesia. Four weeks after injection tumor growth was visible, synergist ablation surgery was performed on the left leg (Overload) and the right leg served as an internal control with sham surgery (Sham). Puromycin (0.04 μmol/g body weight, BW) was injected 30 minutes prior to sacrifice and plantaris muscles (PLAN) were removed and snap‐frozen at day 7 following the surgery. After total protein was extracted, routine Western blotting was performed using 60~120 μg of the total protein. Paired t‐test (Sham vs. Overload) and unpaired t‐test (Con vs. LLC) were used for statistical analysis and the levels of significance was set at 0.05. PLAN weights were comparable between Con and LLC with sham surgery (19.8±1.2 mg vs. 17.3±0.5 mg for Con and LLC, respectively, p=0.077). Seven‐day functional overload increased PLAN weights regardless of tumor inoculation, but the degree of hypertrophy was different (42.7±4.0% vs. 27.6±4.6% for Con and LLC, respectively, p<0.05). LLC mice showed reduced levels of phosphorylated p70S6K (p‐p70) with sham surgery (1.0±0.3 vs. 0.4±0.1, for Con and LLC, respectively, p<0.05) and those with SA surgery (4.4±0.7 vs. 1.6±0.7, for Con and LLC, p<0.05). In harmony with these results, the basal levels of muscle protein synthesis in LLC mice were decreased by 51% compared to Con mice and the levels remained lower after functional overload (2.1±0.1 vs. 1.1±0.1 for Con and LLC, respectively, p<0.05). Interestingly, the basal phosphorylated levels of YAP (p‐YAP) were elevated in LLC mice (1.0±0.1 vs. 2.2±0.1, for Con and LLC, respectively, p<0.05). However, functional overload did not alter the levels of p‐YAP in LLC mice while Con mice significantly increased the levels by 55% (p<0.05). In conclusion, the data suggest that YAP plays a role, at least in part, in decreased anabolic response to functional overload in LLC‐bearing mice.Support or Funding InformationSupported by Louisiana Board of Regents Support Fund (LEQSF(2017‐20)‐RD‐A‐22) to SS.

Mechanosensitive Yes-Associated Protein in Human Skin during Aging

The aim of this work was to examine the content of Yes-associated protein (YAP) in fibroblasts and blood microvessels of human dermis from the development until deep aging (from 20 weeks of pregnancy until 85 years old), and defining of a role of YAP in age-dependent changes in the number of fibroblasts and blood microvessels in the dermis. YAP, proliferating cells nuclear antigen (PCNA), endothelial cells marker CD31 were detected with indirect immunohistochemical technique. Results showed that portion of fibroblasts with positive staining for YAP in the dermis is decreased from 20 weeks of pregnancy to 40 years old. Percent of YAP positive fibroblasts in dermis is increased sufficiently since 41 years old until 60-85 years old group. The content of YAP in blood microvessels in the human dermis is decreased sufficiently from 20 weeks of pregnancy until 40 years old. Age-related changes in the content of YAP in fibroblasts and blood microvessels is not statistically associated with an age-related decrease in total number and percent of PCNA positive fibroblasts, the number of blood vessels in the dermis.

Fufang Xueshuantong protects retinal vascular endothelial cells from high glucose by targeting YAP

Fufang Xueshuantong (FXST), a Chinese patent medicine, is composed of Panax notoginseng, Salviae miltiorrhizae, Astragali Radix and Radix Scrophulariae and has been found to prevent diabetic retinopathy. Yes-associated protein (YAP) participates in the pathophysiology of retinal disease and promotes endothelial cell proliferation and angiogenesis. Although it is known that YAP activity is altered by FXST, the role of YAP in mediating the effect of FXST remains unclear. In high glucose-treated retinal vascular endothelial cells (RVECs), FXST significantly reduced cell viability, the number of migrating cells and tube length in the present study. Moreover, FXST decreased the levels of YAP mRNA and protein and inhibited the expression of vascular endothelial growth factor (VEGF). Transfection of sh-YAP into the cells decreased the ability of FXST to modulate cell migration and tube formation. The effect of FXST on VEGF expression was also decreased. Similar results were obtained when the cells were stimulated with a YAP inhibitor in combination with FXST. Thus, FXST is shown to protect high glucose-injured RVECs via YAP-mediated effects.

Mechanism of YAP1-JUN promoting proliferation and EMT transformation of human laryngeal squamous cell carcinoma cells

Objective To investigate the role of Yes-associated protein 1 (YAP1)-JUN in promoting the proliferation and epithelial mesenchymal transitions (EMT) transformation of laryngeal squamous cell carcinoma. Methods The expression and subcellular localization of YAP1 were detected by tissue immunofluorescence assay. The effects of YAP1 on the proliferation of laryngeal squamous cell were examined by cell clone formation experiment. Western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were used to detect the effect of YAP1 on the expression and transcriptional level of EMT-related molecular markers. The interaction between YAP1 and JUN was detected by immunocoprecipitation (CoIP) and Western blot assay, which regulated the expression of downstream genes to control the EMT process. Results The expression of YAP1 in laryngeal squamous cell carcinoma tissue increased and transferred from cytoplasm to nucleus. The number of clones increased significantly after YAP1 up regulation (P<0.01). The expression level of key gene E-cadherin in epithelial cells was significantly inhibited after YAP1 up (P<0.01), while the expression level of the key genes of interstitial cells, β-catenin, vimentin and N-cadherin was significantly up (P<0.01). YAP1 was interacted with nuclear transcription factor JUN, and the proliferation ability of YAP1 decreased significantly (P<0.01) after the inhibition of JUN expression (P<0.01), and the expression of EMT related molecular markers decreased significantly (P<0.01). Conclusions YAP1 combined with JUN gene promotes the proliferation and EMT transformation of human laryngeal squamous cell carcinoma cells. Key words: Laryngeal neoplasms; Carcinoma, squamous cell; Yes-associated protein 1; Cell proliferation; Epithelial-mesenchymal transition

New Insights into the Roles of Yes-Associated Protein (YAP1) in Colorectal Cancer Development and Progression

Yes-associated protein (YAP1), the downstream effector of the Hippo pathway, plays important roles in the regulation of tissue reconstruction,stem cell proliferation, and development of different cancers. The regulation of YAP1 phosphorylation, YAP1 expressionlevel, and its cellular localization have been considered in cancer development. There are different experimental evidences thatindicate that YAP1 activation results in tumorigenesis, tumor progression, and metastasis. YAP1 is a transcription co-activator, andits dysregulation has been suggested in various cancers including colorectal cancer (CRC). The localization of YAP1 in the nucleusresults in YAP1 interactions with different transcription factors to promote the expression of genes involved in cell proliferation,metastasis, and stem cell maintenance. However, a number of studies have been reported the tumor suppressor role of YAP1 in CRC.Therefore, a better understanding of the YAP1 regulation could be helpful for prevention, diagnosis, and treatment of CRC. In thisreview, we will discuss different roles of YAP1 in CRC progression through the regulatory roles of long non-coding RNAs (LncRNAs),microRNAs (miRNAs) and circular RNAs (CircRNAs) in YAP1 regulation.

Yes-associated protein (YAP) predicts poor prognosis and regulates progression of esophageal squamous cell cancer through epithelial-mesenchymal transition.

The impact of yes-associated protein (YAP) on the prognosis of patients with esophageal squamous cell cancer (ESCC) and its mechanism of action has seldom been reported. In the present study, the role of YAP on the prognosis of patients with ESCC and the mechanism of action of YAP in promoting the progression of ESCC was investigated. Tumor tissue samples from patients with ESCC were collected and the level of YAP expression was detected using immunohistochemical staining. In addition, YAP was knocked-down in ESCC cell lines and the effects on cell migration and invasion were examined. The expression levels of vimentin, N-cadherin, and E-cadherin were further investigated to examine the association between YAP and epithelial-mesenchymal transition (EMT). Results showed that overexpression of YAP was associated with larger lymph node metastasis and poor disease-free survival and overall survival. Compared with patients in early stage ESCC, the association was more significant in patients with late stage ESCC. Univariate and multivariate analyses further indicated that YAP expression could be an independent prognostic factor for ESCC. Downregulation of YAP inhibited cell migration and invasion. Western blot analysis showed that when YAP was knocked down, expression levels of vimentin and N-cadherin were reduced, whereas that of E-cadherin was increased. In conclusion, the results indicates that YAP expression level could be a novel marker for predicting the prognosis of patients with ESCC, and YAP-promoted tumor migration and invasion might be through EMT in ESCC.

YAP promotes the malignancy of endometrial cancer cells via regulation of IL-6 and IL-11

BackgroundEmerging evidence shows that Hippo signal pathways can regulate the progression of various cancer. While the roles of Yes-associated protein (YAP), the key transducer of Hippo signals, in the development of endometrial cancer (EC) are rarely investigated.MethodsThe expression of YAP in endometrial cancer cells and tissues was measured. Its roles in proliferation and expression of interleukins (ILs) were investigated by use of its specific siRNA or inhibitor (verteporfin, VP).ResultsYAP was upregulated in endometrial cancer cells and tissues. Knockdown of YAP or VP can suppress the proliferation while increase its chemo-sensitivity of EC cells. We found that targeted inhibition of YAP can decrease the expression of interleukin-6 (IL-6) and IL-11 in EC cells. Recombinant IL-6 or IL-11 can attenuate si-YAP suppressed proliferation of EC cells. Chromatin immunoprecipitation (ChIP) assay suggested that YAP can directly bind with the promoter of IL-6 and induce its transcription. As to IL-11, inhibitor of NF-κB (BAY 11–7082) can significantly down regulate the mRNA expression of IL-11. Over expression of p65 abolished si-YAP suppressed transcription of IL-11. It suggested that NF-κB was involved in the YAP regulated expression of IL-11.ConclusionsYAP can regulate the proliferation and progression of EC cells. It suggested that targeted inhibition of YAP might be a potent potential approach for EC therapy.

Abstract 2889: The Yes-Associated Protein plays a role in tumor formation, stemness, and therapy response in high risk neuroblastoma

Abstract Neuroblastoma (NB) is the most common extra-cranial solid tumor of childhood. Despite intensive multimodal therapy, &amp;gt;50% of high risk (HR) NB patients relapse with chemotherapy-resistant disease. RAS/RAF/MAPK pathway mutations and increased Yes-Associated Protein (YAP) transcriptional activity are more prevalent in relapsed NB compared to diagnostic tumors. YAP is a transcriptional co-activator, regulated by the Hippo pathway that binds with TEAD in the nucleus to activate genes promoting cell growth, self-renewal, and survival. YAP aberrant transcription has been implicated in many tumor types, yet the role for YAP in NB is unknown. YAP protein is heterogeneously expressed in HR NB cell lines. We used human derived NB cell lines stably transduced to express (NGPYAP) or inhibit (SK-N-ASshYAP, NLFshYAP) YAP to further characterize YAP’s role in NB. While TEAD expression increases with YAP genetic inhibition, expression of YAP paralog TAZ did not change. SK-N-ASshYAP xenografts in NSG mice showed significantly delayed time to tumor formation and slower growth compared to empty vector transduced xenografts. Unmodified NB cells grown as neurospheres in neural basal media showed increased YAP expression and stemness markers, OCT4 and SOX2, by RT-qPCR. OCT4 and SOX2 were dependent on YAP expression as they did not increase in NLFshYAP neurospheres. Furthermore, NLFshYAP had decreased number and size of neurospheres compared to control. Given YAP’s role in tumor stemness, we treated unmodified NB cells with 13-cis-retinoic acid (RA) to see if YAP-induced stemness would overcome RA-induced differentiation. Interestingly, YAP expression and downstream targets, OCT4 and SOX2, increased in response to RA treatment. This suggests that RA paradoxically induces YAP transcriptional activity and may be selecting for a more chemoresistant tumor initiating phenotype. Lastly, YAP knockdown sensitized NRAS- and NF-1-mutated NBs to the MEK inhibitor, Trametinib, and to chemotherapy in vitro. In adult cancers, YAP’s role in therapy resistance is due to its regulation of anti-apoptotic Bcl-2 family proteins. However, YAP knockdown or induced expression in NBs did not change Bcl-2 family protein levels, nor did it affect Bim binding patterns to Mcl-1 or Bcl-2. Thus, investigations are ongoing to understand how YAP negatively regulates Trametinib response. We treated NB cells with Verteporfin (VP), an FDA-approved drug used to treat macular degeneration that inhibits YAP-TEAD interactions in other cancers. While VP inhibited YAP expression in NBs, it also had significant off target effects, potently killing YAP null NBs via light-activated generation of reactive oxygen species. Given the relevance of YAP in relapsed NBs and its effects on NB tumor formation, stemness, and therapy resistance, the need for targeted and specific YAP inhibitors is critical to reinstating therapy sensitivity at relapse. Citation Format: Jenny Shim, Yoo Joo Lee, Kaitlyn Janssen, Alexa Fritz, Kelly C. Goldsmith. The Yes-Associated Protein plays a role in tumor formation, stemness, and therapy response in high risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2889.