Gene Summary

Gene:YY1AP1; YY1 associated protein 1
Aliases: GRNG, HCCA1, HCCA2, YY1AP
Summary:The encoded gene product presumably interacts with YY1 protein; however, its exact function is not known. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:YY1-associated protein 1
Source:NCBIAccessed: 01 September, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 01 September 2019 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.

  • Transfection
  • Carcinogenesis
  • Apoptosis
  • Cell Nucleus
  • Cell Movement
  • Liver Cancer
  • Mice, Transgenic
  • Mutation
  • Phosphoproteins
  • Protein Binding
  • Neoplastic Cell Transformation
  • Transcription
  • Colorectal Cancer
  • HEK293 Cells
  • Gene Expression Profiling
  • Phosphorylation
  • Drug Resistance
  • Cancer Gene Expression Regulation
  • Biomarkers, Tumor
  • Inhibitor of Apoptosis Proteins
  • Antineoplastic Agents
  • Cell Proliferation
  • Nuclear Proteins
  • Disease Models, Animal
  • DNA-Binding Proteins
  • Chromosome 1
  • Melanoma
  • Protein-Serine-Threonine Kinases
  • Signal Transduction
  • Gene Expression
  • Trans-Activators
  • Staging
  • Hepatocellular Carcinoma
  • Ubiquitin Thiolesterase
  • Signal Transducing Adaptor Proteins
  • Breast Cancer
  • Gene Knockdown Techniques
  • Heterografts
  • Oncogenes
  • Cell Survival
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

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: YY1AP1 (cancer-related)

Ito T, Nakamura A, Tanaka I, et al.
CADM1 associates with Hippo pathway core kinases; membranous co-expression of CADM1 and LATS2 in lung tumors predicts good prognosis.
Cancer Sci. 2019; 110(7):2284-2295 [PubMed] Free Access to Full Article Related Publications
Cell adhesion molecule-1 (CADM1) is a member of the immunoglobulin superfamily that functions as a tumor suppressor of lung tumors. We herein demonstrated that CADM1 interacts with Hippo pathway core kinases and enhances the phosphorylation of YAP1, and also that the membranous co-expression of CADM1 and LATS2 predicts a favorable prognosis in lung adenocarcinoma. CADM1 significantly repressed the saturation density elevated by YAP1 overexpression in NIH3T3 cells. CADM1 significantly promoted YAP1 phosphorylation on Ser 127 and downregulated YAP1 target gene expression at confluency in lung adenocarcinoma cell lines. Moreover, CADM1 was co-precipitated with multiple Hippo pathway components, including the core kinases MST1/2 and LATS1/2, suggesting the involvement of CADM1 in the regulation of the Hippo pathway through cell-cell contact. An immunohistochemical analysis of primary lung adenocarcinomas (n = 145) revealed that the histologically low-grade subtype frequently showed the membranous co-expression of CADM1 (20/22, 91% of low-grade; 61/91, 67% of intermediate grade; and 13/32, 41% of high-grade subtypes; P < 0.0001) and LATS2 (22/22, 100% of low-grade; 44/91, 48% of intermediate-grade; and 1/32, 3% of high-grade subtypes; P < 0.0001). A subset analysis of disease-free survival revealed that the membranous co-expression of CADM1 and LATS2 was a favorable prognosis factor (5-year disease-free survival rate: 83.8%), even with nuclear YAP1-positive expression (5-year disease-free survival rate: 83.7%), whereas nuclear YAP1-positive cases with the negative expression of CADM1 and LATS2 had a poorer prognosis (5-year disease-free survival rate: 33.3%). These results indicate that the relationship between CADM1 and Hippo pathway core kinases at the cell membrane is important for suppressing the oncogenic role of YAP1.

Xu Y, He Y, Xu W, et al.
Promotive effects of capillary morphogenetic protein 2 on glioma cell invasion and the molecular mechanism.
Folia Neuropathol. 2019; 57(1):6-15 [PubMed] Related Publications
We aimed to explore the role of capillary morphogenetic protein 2 (CMG2) in glioma cell invasion and the possible molecular mechanism. Glioma cells U87 and U251 stably overexpressing CMG2 were constructed by lentiviral transfection. The changes of cell invasion and migration were tested by Matrigel-transwell assay and scratch assay, respectively. A mouse model with orthotopically transplanted tumour was established to evaluate the effects of CMG2 overexpression on the in vivo invasion of glioma cells and survival time. The differences of filopodia and lamellar pseudopodia among glioma cells with different CMG2 expressions were observed by immunofluorescence assay. The expressions of YAP and p-YAP in glioma cells overexpressing CMG2 or not were compared by Western blot. Compared with the control group, overexpression of CMG2 enhanced the invasion and migration capacities of glioma cells (p < 0.05). The tumour tissues of mice transplanted with glioma cells overexpressing CMG2 were obviously invaded, and their survival time was significantly shortened (p < 0.05). Immunofluorescence staining showed that glioma cells overexpressing CMG2 formed more lamellipodia and filopodia than those of the control group. As glioma cells overexpressing CMG2 formed more pseudopodia, the expression of YAP, a key effector protein of the Hippo pathway, was up-regulated. CMG2 promoted the invasion of glioma cells, and may induce pseudopodium formation by up-regulating YAP expression.

Keller M, Dubois F, Teulier S, et al.
NDR2 kinase contributes to cell invasion and cytokinesis defects induced by the inactivation of RASSF1A tumor-suppressor gene in lung cancer cells.
J Exp Clin Cancer Res. 2019; 38(1):158 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: RASSF1A, a tumor suppressor gene, is frequently inactivated in lung cancer leading to a YAP-dependent epithelial-mesenchymal transition (EMT). Such effects are partly due to the inactivation of the anti-migratory RhoB GTPase via the inhibitory phosphorylation of GEF-H1, the GDP/GTP exchange factor for RhoB. However, the kinase responsible for RhoB/GEF-H1 inactivation in RASSF1A-depleted cells remained unknown.
METHODS: NDR1/2 inactivation by siRNA or shRNA effects on epithelial-mesenchymal transition, invasion, xenograft formation and growth in SCID-/- Beige mice, apoptosis, proliferation, cytokinesis, YAP/TAZ activation were investigated upon RASSF1A loss in human bronchial epithelial cells (HBEC).
RESULTS: We demonstrate here that depletion of the YAP-kinases NDR1/2 reverts migration and metastatic properties upon RASSF1A loss in HBEC. We show that NDR2 interacts directly with GEF-H1 (which contains the NDR phosphorylation consensus motif HXRXXS/T), leading to GEF-H1 phosphorylation. We further report that the RASSF1A/NDR2/GEF-H1/RhoB/YAP axis is involved in proper cytokinesis in human bronchial cells, since chromosome proper segregation are NDR-dependent upon RASSF1A or GEF-H1 loss in HBEC.
CONCLUSION: To summarize, our data support a model in which, upon RASSF1A silencing, NDR2 gets activated, phosphorylates and inactivates GEF-H1, leading to RhoB inactivation. This cascade induced by RASSF1A loss in bronchial cells is responsible for metastasis properties, YAP activation and cytokinesis defects.

Yang CE, Lee WY, Cheng HW, et al.
The antipsychotic chlorpromazine suppresses YAP signaling, stemness properties, and drug resistance in breast cancer cells.
Chem Biol Interact. 2019; 302:28-35 [PubMed] Related Publications
The major obstacle in current cancer therapy is the existence of cancer stem cells (CSCs), which are responsible for therapeutic resistance and contribute to metastasis and recurrence. Identification of reliable biomarkers for diagnostic and therapeutic targets is necessary for drug development and cancer treatment. In this study, we identified that the antipsychotic chlorpromazine (CPZ) exhibited potent anti-breast cancer and anti-CSC capabilities. Treatment with CPZ suppressed stemness properties including mammosphere formation, aldehyde dehydrogenase (ALDH) activity, and stemness-related gene expressions in breast cancer cells and CSCs. Moreover, CPZ increased the susceptibility of breast cancer MCF7 cells and drug-resistant MCF7/ADR cells when combined with chemotherapies. Mechanistically, we identified that CPZ suppressed yes-associated protein (YAP) through modulating Hippo signaling and promoting proteasomal degradation of YAP. Elevated expression of YAP was confirmed to be crucial for stemness-related gene expressions, and was associated with invasiveness and stem-like signatures in breast cancer patients. Moreover, overexpression of YAP conferred poor outcomes particularly of basal-like breast cancer patients. Our data showed that YAP is a promising therapeutic target for breast CSCs, and CPZ has the potential to be a repurposed drug for breast cancer treatment.

Callus BA, Finch-Edmondson ML, Fletcher S, Wilton SD
YAPping about and not forgetting TAZ.
FEBS Lett. 2019; 593(3):253-276 [PubMed] Related Publications
The Hippo pathway has emerged as a major eukaryotic signalling pathway and is increasingly the subject of intense interest, as are the key effectors of canonical Hippo signalling, YES-associated protein (YAP) and TAZ. The Hippo pathway has key roles in diverse biological processes, including network signalling regulation, development, organ growth, tissue repair and regeneration, cancer, stem cell regulation and mechanotransduction. YAP and TAZ are multidomain proteins and function as transcriptional coactivators of key genes to evoke their biological effects. YAP and TAZ interact with numerous partners and their activities are controlled by a complex set of processes. This review provides an overview of Hippo signalling and its role in growth. In particular, the functional domains of YAP and TAZ and the complex mechanisms that regulate their protein stability and activity are discussed. Notably, the similarities and key differences are highlighted between the two paralogues including which partner proteins interact with which functional domains to regulate their activity.

Zhang X, Abdelrahman A, Vollmar B, Zechner D
The Ambivalent Function of YAP in Apoptosis and Cancer.
Int J Mol Sci. 2018; 19(12) [PubMed] Free Access to Full Article Related Publications
Yes-associated protein, a core regulator of the Hippo-YAP signaling pathway, plays a vital role in inhibiting apoptosis. Thus, several studies and reviews suggest that yes-associated protein is a good target for treating cancer. Unfortunately, more and more evidence demonstrates that this protein is also an essential contributor of p73-mediated apoptosis. This questions the concept that yes-associated protein is always a good target for developing novel anti-cancer drugs. Thus, the aim of this review was to evaluate the clinical relevance of yes-associated protein for cancer pathophysiology. This review also summarized the molecules, processes and drugs, which regulate Hippo-YAP signaling and discusses their effect on apoptosis. In addition, issues are defined, which should be addressed in the future in order to provide a solid basis for targeting the Hippo-YAP signaling pathway in clinical trials.

Ji Y, Jia L, Zhang Y, et al.
Antitumor activity of the plant extract morin in tongue squamous cell carcinoma cells.
Oncol Rep. 2018; 40(5):3024-3032 [PubMed] Related Publications
Morin is a naturally occurring bioflavonoid originally isolated from members of the Moraceae family of flowering plants and it possesses antitumor activity in various human cancer cells. The present study explored the antitumor effects of morin in tongue squamous cell carcinoma (TSCC) cells in vitro and investigated the underlying molecular events. A TSCC cell line was treated with different doses of morin for up to 48 h. Analyses of cell viability, using Cell Counting Kit‑8 (CCK‑8), EdU incorporation, colony formation, flow cytometric analysis of cell cycle distribution and apoptosis, wound healing assay, western blot analysis and qRT‑PCR assays, were then performed. The data revealed that morin treatment reduced Cal27 cell proliferation and reduced the migration capacity of tumor cells in a dose‑dependent manner. Morin treatment also significantly upregulated mammalian sterile 20‑like 1 (MST1) and MOB kinase activator 1 (MOB1) phosphorylation in CAL27 cells, but suppressed nuclear translocation of yes‑associated protein (YAP) through the induction of YAP phosphorylation in Cal27 cells. Moreover, the expression of YAP‑targeting genes, such as CTGF, CYR61 and ANKRD, was downregulated in morin‑treated TSCC cells, indicating that morin was able to activate the Hippo signaling pathway to inhibit YAP nuclear translocation and YAP‑related transcriptional activity in TSCC cells. In conclusion, the data from the present study demonstrated that morin produces anti‑TSCC activity in vitro through activation of the Hippo signaling pathway and the downstream suppression of YAP activity in TSCC cells. Future studies should assess the clinical antitumor effects of morin.

Song H, Wu T, Xie D, et al.
WBP2 Downregulation Inhibits Proliferation by Blocking YAP Transcription and the EGFR/PI3K/Akt Signaling Pathway in Triple Negative Breast Cancer.
Cell Physiol Biochem. 2018; 48(5):1968-1982 [PubMed] Related Publications
BACKGROUND/AIMS: Dysregulated expression of WW domain-binding protein 2 (WBP2) is associated with poor prognosis in ER+ breast cancer patients. However, its role in triple negative breast cancer (TNBC) has not been previously assessed. Therefore, we aimed to elucidate the functional mechanism of WBP2 in TNBC cells.
METHODS: qRT-PCR, western blotting, and immunohistochemical staining were used to evaluate WBP2 expression in TNBC patient tumors and cell lines. HCC1937 and MDA-MB-231 cells transiently transfected with WBP2 small interfering RNA (siRNA), miR-613 mimics, or miR-613 inhibitors were subject to assays for cell viability, apoptosis and cell cycle distribution. Co-immunoprecipitation, western blotting or qRT-PCR were employed to monitor changes in signaling pathway-related genes and proteins. Luciferase assays were performed to assess whether WBP2 is a direct target of miR-613. The effect of miR-613 on tumor growth was assessed in vivo using mouse xenograft models.
RESULTS: The expression of WBP2 was upregulated in TNBC tissues and cells. Expression of WBP2 was significantly correlated with Ki67 in TNBC patients. Knockdown of WBP2 inhibited cellular proliferation, promoted apoptosis, and induced cell cycle arrest of TNBC cells. miR-613 directly bound to the 3'-untranslated region (3'-UTR) of WBP2 and regulated the expression of WBP2. Moreover, miR-613 reduced the expression of WBP2 and suppressed tumor growth of TNBC cells in vivo. Knockdown of WBP2 inhibited YAP transcription and the EGFR/PI3K/Akt signaling pathway in TNBC cells, and these effects were reversed by inhibition of miR-613.
CONCLUSION: WBP2 overexpression is associated with the poor prognosis of TNBC patients and the miR-613-WBP2 axis represses TNBC cell growth by inactivating YAP-mediated gene expression and the EGFR/PI3K/Akt signaling pathway.

Song R, Gu D, Zhang L, et al.
Functional significance of Hippo/YAP signaling for drug resistance in colorectal cancer.
Mol Carcinog. 2018; 57(11):1608-1615 [PubMed] Related Publications
Colorectal cancer is a leading cause of cancer-related death worldwide. While early stage colorectal cancer can be removed by surgery, patients with advanced disease are treated by chemotherapy, with 5-Fluorouracil (5-FU) as a main ingredient. However, most patients with advanced colorectal cancer eventually succumb to the disease despite some responded initially. Thus, identifying molecular mechanisms responsible for drug resistance will help design novel strategies to treat colorectal cancer. In this study, we analyzed an acquired 5-FU resistant cell line, LoVo-R, and determined that elevated expression of YAP target genes is a major alteration in the 5-FU resistant cells. Hippo/YAP signaling, a pathway essential for cell polarity, is an important regulator for tissue homeostasis, organ size, and stem cells. We demonstrated that knockdown of YAP1 sensitized LoVo-R cells to 5-FU treatment in cultured cells and in mice. The relevance of our studies to colorectal cancer patients is reflected by our discovery that high expression of YAP target genes in the tumor was associated with an increased risk of cancer relapse and poor survival in a larger cohort of colorectal cancer patients who underwent 5-FU-related chemotherapy. Taken together, we demonstrate a critical role of YAP signaling for drug resistance in colorectal cancer.

Lu T, Sun L, Zhu X
Yes-associated protein enhances proliferation and attenuates sensitivity to cisplatin in human gastric cancer cells.
Biomed Pharmacother. 2018; 105:1269-1275 [PubMed] Related Publications
BACKGROUND: Yes-associated protein (YAP) is upregulated in many cancer types, and its overexpression is involved in tumor cell proliferation, metastasis and resistance to chemotherapy. In the present study, we aimed to investigate the potential role of YAP in the development and progression of gastric cancer.
METHODS: YAP levels were analyzed in human gastric cancer and adjacent normal tissues by Western blotting and immunohistochemistry. Potential roles of YAP in regulating gastric cancer cell proliferation and sensitivity to cisplatin were examined by genetic manipulation in vitro. The molecular signaling was determined to understand the mechanisms of observed YAP effects.
RESULTS: YAP level was higher in gastric cancer tissues as compared to paired normal tissues. Knockdown of YAP attenuated gastric cancer cell proliferation and enhanced sensitivity to cisplatin in vitro while YAP overexpression possessed the opposite effects. YAP regulated Epidermal growth factor receptor (EGFR) expression and its downstream AKT and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway in gastric cancer cells.
CONCLUSION: YAP enhances gastric cancer cell proliferation and attenuates sensitivity to cisplatin potentially through targeting the EGFR signaling, indicating that YAP/EGFR signaling axis may serve as a potential target for treatment of gastric cancer.

Zheng CH, Chen XM, Zhang FB, et al.
Inhibition of CXCR4 regulates epithelial mesenchymal transition of NSCLC via the Hippo-YAP signaling pathway.
Cell Biol Int. 2018; 42(10):1386-1394 [PubMed] Related Publications
CXCR4 has been shown to play a key role in the metastasis of non-small cell lung cancer (NSCLC). And CXCR may be associated with the Hippo-Yes kinase-associated protein (YAP) pathway, thus involving in the occurrence and progression of NSCLC. This study aims to investigate the effect of CXCR4 inhibition on epithelial-mesenchymal transition (EMT), invasion and migration of NSCLC cells via the Hippo-YAP pathway. QRT-PCR and Western blot were employed to detect CXCR4 expression in NSCLC cell lines. A549 and H1299 cells were treated with WZ811 (0, 10, 30, and 50 µM), and A549 cells were also divided into the Control, WZ811, YAP siRNA, and WZ811 + YAP groups. Wound-healing, Transwell assay, immunofluorescent staining, and a luciferase reporter gene assay were performed in this experiment. Compared with human bronchial epithelial (HBE) cells, CXCR4 expression was up-regulated in NSCLC cell lines. WZ811 increased E-cadherin; decreased expression of Twist, vimentin, Snail, p-YAP, CTGF, and BIRC5; blocked GTIIC reporter activity; and reduced migration and invasion of A549 cells, all in a dose-dependent manner. YAP siRNA had a similar effect to WZ811 by inhibiting EMT, invasion and migration of A549 cells. However, compared with A549 cells in the YAP siRNA and WZ811 groups, cells in the WZ811 + YAP group showed a dramatically enhanced EMT phenotype as well as invasion and migration abilities. Inhibition of CXCR4 may reduce EMT, invasion and migration of NSCLC cells, thereby providing a new therapeutic target for NSCLC.

Jin D, Wu Y, Shao C, et al.
Norcantharidin reverses cisplatin resistance and inhibits the epithelial mesenchymal transition of human non‑small lung cancer cells by regulating the YAP pathway.
Oncol Rep. 2018; 40(2):609-620 [PubMed] Free Access to Full Article Related Publications
Non‑small cell lung cancer (NSCLC) accounts for >80% of all lung cancer cases, which are the leading cause of cancer‑related mortality worldwide. The clinical efficacy of available therapies for NSCLC is often limited due to the development of resistance to anticancer drugs, particularly to cisplatin (DDP). Norcantharidin (NCTD) is a traditional Chinese medicine used in the treatment of many types of cancer, to which patients do not develop resistance. The aim of the present study was to examine the potential synergistic effects of NCTD and DPP on the viability of the the DDP‑resistant NSCLC cell line, A549/DDP. We further explored the potential underlying mechanisms by examining the expression of the oncogene, Yes-associated protein 1 (YAP), whose activation was recently found to be associated with drug resistance. We further examined a series of human lung cancer cell lines and tissues from patients with lung cancer, which revealed that YAP activation contributed to lung cancer initiation, progression and metastasis, and was associated with a poor prognosis, and confering resistance against targeted therapies. Moreover, YAP expression was evaluated in the A549/DDP cells treated with NCTD, DDP, or both drugs. The combined treatment significantly sensitized the A549/DDP cells to DDP‑induced growth inhibition by reducing YAP promoter activity (based on transcriptional expression) and the expression of its target genes, connective tissue growth factor (CTGF) and cysteine rich angiogenic inducer 61 (CYR61). Furthermore, compared to the individual treatments, combined treatment increased cell apoptosis and senescence, and decreased epithelial‑to‑mesenchymal transition and the cell migratory and invasive ability. On the whole, our data indicate that the application of NCTD with reverses DDP resistance and thus, this combined treatment may have promising prospects for use in improving the outcome of patients with NSCLC.

Liu Y, Wang G, Liang Z, et al.
Lysyl oxidase: A colorectal cancer biomarker of lung and hepatic metastasis.
Thorac Cancer. 2018; 9(7):785-793 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Colorectal cancer (CRC) is a common and lethal disease in which distant metastasis remains the primary cause of death. Paradoxical roles of LOX have been reported in CRC, and the intracellular function of LOX has also recently been determined. Correlations of LOX expression and its intracellular localization with clinicopathological features in CRC patients remain largely unknown. The aim of the present study was to explore the potential roles of LOX in CRC.
METHODS: LOX messenger RNA expression was assayed by quantitative PCR in eight paired normal mucosa and tumor tissues. Immunohistochemistry was conducted using tissue arrays to investigate LOX expression in 201 CRC patients. Regulation of LOX by YAP and TEAD4 was explored by YAP or TEAD4 short hairpin RNA interference in a LoVo cell line.
RESULTS: LOX messenger RNA expression was elevated in some CRC specimens, and LOX nuclear localization was detected in CRC tumor tissues. LOX nuclear localization was found to correlate with lung/hepatic metastasis, elevated serum carcinoembryonic antigen concentration, and mucinous tumor type (P < 0.05). Nuclear LOX expression was found to be associated with poor overall and disease-free survival (P < 0.05), and postoperative lung/hepatic metastasis (P < 0.05). Knockdown of YAP or TEAD4 induced downregulation of LOX expression.
CONCLUSIONS: LOX nuclear localization was significantly associated with poor survival in patients with CRC. Nuclear LOX expression was correlated with synchronous or postoperative lung/hepatic metastasis. LOX may prove to be a potential target gene of YAP and TEAD4.

Santoro R, Zanotto M, Carbone C, et al.
MEKK3 Sustains EMT and Stemness in Pancreatic Cancer by Regulating YAP and TAZ Transcriptional Activity.
Anticancer Res. 2018; 38(4):1937-1946 [PubMed] Related Publications
BACKGROUND/AIM: Pancreatic cancer is one of the most threatening and poorly understood human malignancies. MEKK3 (MAP3K3) is a serine/threonine kinase activated by different signaling pathways. YAP and TAZ are critical oncogenic effectors in pancreatic cancer. We hypothesized that MEKK3 could sustain pancreatic cancer by inducing YAP/TAZ oncogenic activities.
MATERIALS AND METHODS: In Panc1 and AsPC1 pancreatic cancer cell lines MEKK3 was knocked-out (KO) by the CRISPR/Cas9 method. These cells were used to evaluate MEKK3 contribution to the expression of YAP/TAZ and their target genes, cell migration, stemness, and in vivo tumor growth.
RESULTS: MEKK3 KO reduced both EMT and cell migration, the size of 3D colonies and the percentage of CD44
CONCLUSION: Silencing of MEKK3 represents a valid approach to revert in vivo the aggressiveness of pancreatic cancer by modulating YAP/TAZ transcriptional activities.

Jiang Z, Zhou C, Cheng L, et al.
Inhibiting YAP expression suppresses pancreatic cancer progression by disrupting tumor-stromal interactions.
J Exp Clin Cancer Res. 2018; 37(1):69 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Hippo/YAP pathway is known to be important for development, growth and organogenesis, and dysregulation of this pathway leads to tumor progression. We and others find that YAP is up-regulated in pancreatic ductal adenocarcinoma (PDAC) and associated with worse prognosis of patients. Activated pancreatic stellate cells (PSCs) forming the components of microenvironment that enhance pancreatic cancer cells (PCs) invasiveness and malignance. However, the role and mechanism of YAP in PDAC tumor-stromal interaction is largely unknown.
METHODS: The expression of YAP in Pancreatic cancer cell lines and PDAC samples was examined by Western blot and IHC. The biological role of YAP on cancer cell proliferation, epithelial-mesenchymal transition (EMT) and invasion were evaluated by MTT, Quantitative real-time PCR analysis, Western blot analysis and invasion assay. The effect of YAP on PSC activation was evaluated by PC-PSC co-culture conditions and xenograft PDAC mouse model.
RESULTS: Firstly, knockdown of YAP inhibits PDAC cell proliferation and invasion in vitro. In addition, YAP modulates the PC and PSC interaction via reducing the production of connective tissue growth factor (CTGF) from PCs, inhibits paracrine-mediated PSC activation under PC-PSC co-culture conditions and in turn disrupts TGF-β1-mediated tumor-stromal interactions. Lastly, inhibiting YAP expression prevents tumor growth and suppresses desmoplastic reaction in vivo.
CONCLUSIONS: These results demonstrate that YAP contributes to the proliferation and invasion of PC and the activation of PSC via tumor-stromal interactions and that targeting YAP may be a promising therapeutic strategy for PDAC treatment.

Mueller S, Engleitner T, Maresch R, et al.
Evolutionary routes and KRAS dosage define pancreatic cancer phenotypes.
Nature. 2018; 554(7690):62-68 [PubMed] Free Access to Full Article Related Publications
The poor correlation of mutational landscapes with phenotypes limits our understanding of the pathogenesis and metastasis of pancreatic ductal adenocarcinoma (PDAC). Here we show that oncogenic dosage-variation has a critical role in PDAC biology and phenotypic diversification. We find an increase in gene dosage of mutant KRAS in human PDAC precursors, which drives both early tumorigenesis and metastasis and thus rationalizes early PDAC dissemination. To overcome the limitations posed to gene dosage studies by the stromal richness of PDAC, we have developed large cell culture resources of metastatic mouse PDAC. Integration of cell culture genomes, transcriptomes and tumour phenotypes with functional studies and human data reveals additional widespread effects of oncogenic dosage variation on cell morphology and plasticity, histopathology and clinical outcome, with the highest Kras

Yu SJ, Yang L, Hong Q, et al.
MicroRNA-200a confers chemoresistance by antagonizing TP53INP1 and YAP1 in human breast cancer.
BMC Cancer. 2018; 18(1):74 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Emerging evidence suggests molecular and phenotypic association between treatment resistance and epithelial-mesenchymal transition (EMT) in cancer. Compared with the well-defined molecular events of miR-200a in EMT, the role of miR-200a in therapy resistance remains to be elucidated.
METHODS: Breast cancer cells transfected with mimic or inhibitor for miR-200a was assayed for chemoresistance in vitro. miR-200a expression was assessed by quantitative real-time PCR (qRT-PCR) in breast cancer patients treated with preoperative chemotherapy. Luciferase assays, cell proliferation assay were performed to identify the targets of miR-200a and the mechanism by which it promotes treatment resistance. Survival analysis was used to evaluate the prognosis value of miR-200a.
RESULTS: In this study, our results showed ectopic expression of miR-200a promotes chemoresistance in breast cancer cell lines to several chemotherapeutic agents, whereas inhibition of miR-200a enhances gemcitabine chemosensitivity in resistance cancer cells. We found overexpression of miR-200a was closely associated with poor response to preoperative chemotherapy and poor prognosis in breast cancer patients. Furthermore, knockdown of YAP1 and TP53INP1 phenocopied the effects of miR-200a overexpression, and confirmed that TP53INP1 is a novel target of miR-200a. Remarkably, TP53INP1 expression is inversely correlated with miR-200a expression in Breast cancer cell lines. Taken together, these clinical and experimental results demonstrate that miR-200a is a determinant of chemoresistance of breast cancer.
CONCLUSIONS: Upregulated miR-200a enhances treatment resistance via antagonizing TP53INP1 and YAP1 in breast cancer.

Lee TF, Tseng YC, Nguyen PA, et al.
Enhanced YAP expression leads to EGFR TKI resistance in lung adenocarcinomas.
Sci Rep. 2018; 8(1):271 [PubMed] Free Access to Full Article Related Publications
Epidermal growth factor receptor (EGFR) mutation is prevalently expressed in lung adenocarcinoma cases and acts as one of the major driving oncogenes. EGFR tyrosine kinase inhibitors (TKIs) have been used in patients with EGFR-mutant as an effective targeted therapy in lung adenocarcinoma, but drug resistance and tumor recurrence inevitably occurs. Recently, Yes-associate protein (YAP) has been reported to promote multiple cancer cell properties, such as promoting cell proliferation, epithelial-mesenchymal transition and drug resistance. This study investigated the roles of YAP in TKI-resistant lung adenocarcinoma. In TKI-sensitive cells, enhanced YAP expression leads to TKI resistant. Also, upregulated YAP expression and activation were detected in long-term TKI-induced resistant cells. With reduced YAP expression using shRNA or YAP inhibitors, TKI-resistant cells become TKI-sensitive. reduced xenograft tumor size in nude mice and Moreover, combined EGFR TKI and a YAP inhibitor, statin, prolonged survival among lung cancer patients analyzed by Taiwan National Health Insurance Research database. These observations revealed the importance of YAP in promoting TKI-resistance and combined YAP inhibition can be a potential therapy delaying the occurrence of TKI-resistance in lung adenocarcinoma.

Guan ZB, Cao YS, Li Y, et al.
Knockdown of lncRNA GHET1 suppresses cell proliferation, invasion and LATS1/YAP pathway in non small cell lung cancer.
Cancer Biomark. 2018; 21(3):557-563 [PubMed] Related Publications
BACKGROUND: The aim in this study was to explore the role of long non-coding RNA GHET1 in development of non small cell lung cancer (NSCLC).
METHODS: LncRNA GHET1 expression levels were analyzed by qRT-PCR in tumor tissues and adjacent normal tissues in NSCLC. Measuring the cell proliferation and invasion abilities by CCK8, cell colony formation and transwell invasion assays. Relative protein expression was analyzed by western blot assays.
RESULTS: Expression of lncRNA GHET1 was notably higher in NSCLC tissues compared with adjacent normal tissues by using qRT-PCR analyses. Higher lncRNA GHET1 expression associated with lymph node metastasis, TNM stage and showed poor outcome in NSCLC patients. Knockdown of lncRNA GHET1 suppressed cell proliferation and invasion capacity and Epithelial-Mesenchymal Transition (EMT) phenomenon of NSCLC cells. Moreover, we demonstrated that knockdown of lncRNA GHET1 suppresses LATS1/YAP pathway signaling pathway by downregulating YAP1 expression in NSCLC cells.
CONCLUSIONS: GHET1 predicted a poor outcome and acted as a tumor-promoting gene in NSCLC. Thus, inhibition of GHET1 may be a potential target of NSCLC treatment.

Zhu C, Ji X, Zhang H, et al.
Deubiquitylase USP9X suppresses tumorigenesis by stabilizing large tumor suppressor kinase 2 (LATS2) in the Hippo pathway.
J Biol Chem. 2018; 293(4):1178-1191 [PubMed] Free Access to Full Article Related Publications
The Hippo pathway plays important roles in controlling organ size and in suppressing tumorigenesis through large tumor suppressor kinase 1/2 (LATS1/2)-mediated phosphorylation of YAP/TAZ transcription co-activators. The kinase activity of LATS1/2 is regulated by phosphorylation in response to extracellular signals. Moreover, LATS2 protein levels are repressed by the ubiquitin-proteasome system in conditions such as hypoxia. However, the mechanism that removes the ubiquitin modification from LATS2 and thereby stabilizes the protein is not well understood. Here, using tandem affinity purification (TAP), we found that anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase complex, and USP9X, a deubiquitylase, specifically interact with LATS2. We also found that although APC1 co-localizes with LATS2 to intracellular vesicle structures, it does not regulate LATS2 protein levels and activity. In contrast, USP9X ablation drastically diminished LATS2 protein levels. We further demonstrated that USP9X deubiquitinates LATS2 and thus prevents LATS2 degradation by the proteasome. Furthermore, in pancreatic cancer cells, USP9X loss activated YAP and enhanced the oncogenic potential of the cells. In addition, the tumorigenesis induced by the USP9X ablation depended not only on LATS2 repression, but also on YAP/TAZ activity. We conclude that USP9X is a deubiquitylase of the Hippo pathway kinase LATS2 and that the Hippo pathway functions as a downstream signaling cascade that mediates USP9X's tumor-suppressive activity.

Ghiso E, Migliore C, Ciciriello V, et al.
YAP-Dependent AXL Overexpression Mediates Resistance to EGFR Inhibitors in NSCLC.
Neoplasia. 2017; 19(12):1012-1021 [PubMed] Free Access to Full Article Related Publications
The Yes-associated protein (YAP) is a transcriptional co-activator upregulating genes that promote cell growth and inhibit apoptosis. The main dysregulation of the Hippo pathway in tumors is due to YAP overexpression, promoting epithelial to mesenchymal transition, cell transformation, and increased metastatic ability. Moreover, it has recently been shown that YAP plays a role in sustaining resistance to targeted therapies as well. In our work, we evaluated the role of YAP in acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in lung cancer. In EGFR-addicted lung cancer cell lines (HCC4006 and HCC827) rendered resistant to several EGFR inhibitors, we observed that resistance was associated to YAP activation. Indeed, YAP silencing impaired the maintenance of resistance, while YAP overexpression decreased the responsiveness to EGFR inhibitors in sensitive parental cells. In our models, we identified the AXL tyrosine kinase receptor as the main YAP downstream effector responsible for sustaining YAP-driven resistance: in fact, AXL expression was YAP dependent, and pharmacological or genetic AXL inhibition restored the sensitivity of resistant cells to the anti-EGFR drugs. Notably, YAP overactivation and AXL overexpression were identified in a lung cancer patient upon acquisition of resistance to EGFR TKIs, highlighting the clinical relevance of our in vitro results. The reported data demonstrate that YAP and its downstream target AXL play a crucial role in resistance to EGFR TKIs and suggest that a combined inhibition of EGFR and the YAP/AXL axis could be a good therapeutic option in selected NSCLC patients.

Eibl G, Rozengurt E
KRAS, YAP, and obesity in pancreatic cancer: A signaling network with multiple loops.
Semin Cancer Biol. 2019; 54:50-62 [PubMed] Article available free on PMC after 01/02/2020 Related Publications
Pancreatic ductal adenocarcinoma (PDAC) continues to be a lethal disease with no efficacious treatment modalities. The incidence of PDAC is expected to increase, at least partially because of the obesity epidemic. Increased efforts to prevent or intercept this disease are clearly needed. Mutations in KRAS are initiating events in pancreatic carcinogenesis supported by genetically engineered mouse models of the disease. However, oncogenic KRAS is not entirely sufficient for the development of fully invasive PDAC. Additional genetic mutations and/or environmental, nutritional, and metabolic stressors, e.g. inflammation and obesity, are required for efficient PDAC formation with activation of KRAS downstream effectors. Multiple factors "upstream" of KRAS associated with obesity, including insulin resistance, inflammation, changes in gut microbiota and GI peptides, can enhance/modulate downstream signals. Multiple signaling networks and feedback loops "downstream" of KRAS have been described that respond to obesogenic diets. We propose that KRAS mutations potentiate a signaling network that is promoted by environmental factors. Specifically, we envisage that KRAS mutations increase the intensity and duration of the growth-promoting signaling network. As the transcriptional activator YAP plays a critical role in the network, we conclude that the rationale for targeting the network (at different points), e.g. with FDA approved drugs such as statins and metformin, is therefore compelling.

Ho YJ, Lin YM, Huang YC, et al.
Prognostic significance of high YY1AP1 and PCNA expression in colon adenocarcinoma.
Biochem Biophys Res Commun. 2017; 494(1-2):173-180 [PubMed] Related Publications
To investigate the relationship between YY1AP1 and various clinicopathological features of colon adenocarcinoma (COAD), we conducted immunohistochemical (IHC) analyses of human tissue microarrays. We found that YY1AP1 protein expression was significantly higher in tumor tissue of the colon and liver, and was significantly lower in tumor tissue of the kidney. An analysis that employed the SurvExpress database indicated that increased expression of YY1AP1 mRNA was significantly associated with the overall survival of COAD patients. To clarify the validity of YY1AP1 or PCNA as determined by the IHC analysis was performed on 59 paired samples from COAD and adjacent normal tissue. Statistically significant differences of immunoreactivity for YY1AP1 or PCNA protein expression was observed between COAD tissue and adjacent normal tissue. High protein expression levels of YY1AP1 and PCNA were also found to be significantly correlated with M-class and distant metastasis. We also determined that YY1AP1 was correlated with PCNA expression in COAD samples, and Kaplan-Meier survival curves indicated that YY1AP1 protein expression was significantly associated with poor survival. Finally, a univariate analysis demonstrated that YY1AP1 protein expression was related to YY1AP1 score, and multivariate analysis revealed that the YY1AP1 protein expression level was an independent risk factor of overall COAD survival. Taken together, our findings indicate that YY1AP1 expression plays an important role in the tumorigenesis and progression of COAD and could serve as a clinical prognostic indicator for COAD.

Li W, Cao Y, Xu J, et al.
YAP transcriptionally regulates COX-2 expression and GCCSysm-4 (G-4), a dual YAP/COX-2 inhibitor, overcomes drug resistance in colorectal cancer.
J Exp Clin Cancer Res. 2017; 36(1):144 [PubMed] Article available free on PMC after 01/02/2020 Related Publications
BACKGROUND: Chemotherapy resistance remains a major challenge in cancer treatment. COX-2 (cyclooxygenase 2) is involved in drug resistance and poor prognosis of many neoplastic diseases or cancers. However, investigations identifying new modulators of COX-2 pathway and searching for new chemicals targeting these valid resistant biomarkers are still greatly needed.
METHODS: HCT15, HCT-116, HT-29, COLO205, FHC, IMCE, SW480 cell lines were used to detect the expression of YAP and COX-2. Site-directed mutagenesis, luciferase reporter analysis and ChIP assay were used to test whether YAP activated COX-2 transcription through interaction with TEAD binding sites in the promoter of COX-2. Cell line models exhibiting overexpression or knockdown of some genes were generated using transfection agents. Coimmunoprecipitation was used to detect protein mutual interaction. mRNA and protein levels were measured by qRT-PCR and western blot respectively.
RESULTS: Here, we reported that both YAP and COX-2 were overexpressed in colorectal cancer cells. YAP increased COX-2 expression at the level of transcription requiring intact TEAD binding sites in the COX-2 promoter. YAP conferred drug resistance through COX-2 and its related effectors such as MCL, MDR, Survivin. GCCSysm-4 (G-4), a YAP and COX-2 inhibitor, effectively inhibited both YAP and COX-2 activation, induced apoptosis and decreased viability in Taxol-resistant cells. Inhibition of YAP and COX-2 acted synergistically and more efficiently reduced the resistance of CRC cells than either of them alone.
CONCLUSIONS: Our data provide new mechanisms that YAP is a new upstream regulator of COX-2 pathway and plays an important role in conferring resistance in CRC cells. G-4, targeting YAP-COX-2, may be a novel valuable strategy to combat resistance in CRC.

Mello SS, Valente LJ, Raj N, et al.
A p53 Super-tumor Suppressor Reveals a Tumor Suppressive p53-Ptpn14-Yap Axis in Pancreatic Cancer.
Cancer Cell. 2017; 32(4):460-473.e6 [PubMed] Article available free on PMC after 01/02/2020 Related Publications
The p53 transcription factor is a critical barrier to pancreatic cancer progression. To unravel mechanisms of p53-mediated tumor suppression, which have remained elusive, we analyzed pancreatic cancer development in mice expressing p53 transcriptional activation domain (TAD) mutants. Surprisingly, the p53

Slemmons KK, Crose LES, Riedel S, et al.
A Novel Notch-YAP Circuit Drives Stemness and Tumorigenesis in Embryonal Rhabdomyosarcoma.
Mol Cancer Res. 2017; 15(12):1777-1791 [PubMed] Article available free on PMC after 01/02/2020 Related Publications
Rhabdomyosarcoma (RMS), a cancer characterized by skeletal muscle features, is the most common soft-tissue sarcoma of childhood. While low- and intermediate-risk groups have seen improved outcomes, high-risk patients still face a 5-year survival rate of <30%, a statistic that has not changed in over 40 years. Understanding the biologic underpinnings of RMS is critical. The developmental pathways of Notch and YAP have been identified as potent but independent oncogenic signals that support the embryonal variant of RMS (eRMS). Here, the cross-talk between these pathways and the impact on eRMS tumorigenesis is reported. Using human eRMS cells grown as three-dimensional (3D) rhabdospheres, which enriches in stem cells, it was found that Notch signaling transcriptionally upregulates

Luo G, Li B, Duan C, et al.
c‑Myc promotes cholangiocarcinoma cells to overcome contact inhibition via the mTOR pathway.
Oncol Rep. 2017; 38(4):2498-2506 [PubMed] Related Publications
The loss of contact inhibition is a hallmark of a wide range of human cancer cells. Yet, the precise mechanism behind this process is not fully understood. c‑Myc plays a pivotal role in carcinogenesis, but its involvement in regulating contact inhibition has not been explored to date. Here, we report that c‑Myc plays an important role in abrogating contact inhibition in human cholangiocarcinoma (CCA) cells. Our data show that the protein level of c‑Myc obviously decreased in contact-inhibited normal biliary epithelial cells. However, CCA cells sustain high protein levels of c‑Myc and keep strong proliferation ability in confluent conditions. Importantly, the suppression of c‑Myc by inhibitor or siRNA induced G0/G1 phase cell cycle arrest in confluent CCA cells. We demonstrate that the inhibition of c‑Myc suppressed the activity of mammalian target of rapamycin (mTOR) in confluent CCA cells, and mTOR inhibition induced G0/G1 phase cell cycle arrest in confluent CCA cells. In confluent CCA cells, the activity of Merlin is downregulated, and Yes-associated protein (YAP) sustains high levels of activity. Furthermore, YAP inhibition not only induced G0/G1 phase cell cycle arrest, but also decreased c‑Myc expression in confluent CCA cells. These results indicate that Merlin/YAP/c‑Myc/mTOR signaling axis promotes human CCA cell proliferation by overriding contact inhibition. We propose that overriding c‑Myc‑mediated contact inhibition is implicated in the development of CCA.

Pan Z, Tian Y, Zhang B, et al.
YAP signaling in gastric cancer-derived mesenchymal stem cells is critical for its promoting role in cancer progression.
Int J Oncol. 2017; 51(4):1055-1066 [PubMed] Article available free on PMC after 01/02/2020 Related Publications
Cancer-associated mesenchymal stem cells (MSCs) are critically involved in tumor development and progression. However, the mechanisms of action for MSCs in cancer remain largely unknown. Herein, we reported that the expression of Yes-associated protein 1 (YAP) was higher in gastric cancer derived mesenchymal stem cells (GC‑MSCs) than that in bone marrow derived MSCs (BM‑MSCs). YAP knockdown not only inhibited the growth, migration and invasion, and stemness of GC‑MSCs, but also suppressed their promoting effect on gastric cancer growth in vitro and in vivo. In addition, the interference of YAP expression in GC‑MSCs also attenuated the promoting role of gastric cancer cells in endothelial cell tube formation and migration. Mechanistically, YAP knockdown reduced the activation of β-catenin and its target genes in gastric cancer cells by GC‑MSCs. Taken together, these findings suggest that YAP activation in GC‑MSCs plays an important role in promoting gastric cancer progression, which may represent a potential target for gastric cancer therapy.

Ji XY, Zhong G, Zhao B
Molecular mechanisms of the mammalian Hippo signaling pathway.
Yi Chuan. 2017; 39(7):546-567 [PubMed] Related Publications
The Hippo pathway plays an evolutionarily conserved fundamental role in controlling organ size in multicellular organisms. Importantly, evidence from studies of patient samples and mouse models clearly indicates that deregulation of the Hippo signaling pathway plays a crucial role in the initiation and progression of many different types of human cancers. The Hippo signaling pathway is regulated by various stimuli, such as mechanical stress, G-protein coupled receptor signaling, and cellular energy status. When activated, the Hippo kinase cascade phosphorylates and inhibits the transcription co-activator YAP (Yes-associated protein), and its paralog TAZ (transcriptional coactivator with PDZ-binding motif), resulting in their cytoplasmic retention and degradation. When the Hippo signaling pathway is inactive, dephosphorylated YAP/TAZ translocate into the nucleus and activate gene transcription through binding to TEAD (TEA domain) family and other transcription factors. Such changes in gene expression promote cell proliferation and stem cell/progenitor cell self-renewal but inhibit apoptosis, thereby coordinately promote increase in organ size, tissue regeneration, and tumorigenesis. In this review, we summarize the molecular mechanisms of the mammalian Hippo signaling pathway with special emphasis on the Hippo kinase cascade and its upstream signals, the Hippo signaling pathway regulation of YAP and the mechanisms of YAP in regulation of gene transcription.

Guo Y, Cui J, Ji Z, et al.
miR-302/367/LATS2/YAP pathway is essential for prostate tumor-propagating cells and promotes the development of castration resistance.
Oncogene. 2017; 36(45):6336-6347 [PubMed] Related Publications
Clinical intervention for patients with advanced prostate cancer (PCa) remains challenging due to the inevitable recurrence of castration-resistant prostate cancer (CRPC) after androgen deprivation therapy (ADT). Cancer stem cells (CSCs) with serial tumor-propagating capacity are considered to be the driving force for PCa progression and recurrence. In this study, we report that the miR-302/367 cluster, a previously identified potent pluripotency regulator, is upregulated in prostate tumors. Specifically, the forced expression of the miR-302/367 cluster accelerates the in vitro and in vivo growth of PCa cells and their resistance to androgen ablation, whereas the knockdown of the miR-302/367 cluster using anti-sense RNA suppresses the incidence of formation, growth rate and endpoint weight of PCa cell tumors. Mechanistically, we find that LATS2, a key component of the tumor-suppressive Hippo signaling pathway, acts as a direct target of the miR-302/367 cluster in PCa cells. The downregulation of LATS2 by the miR-302/367 cluster reduces the phosphorylation and enhances the nuclear translocation of the YAP oncoprotein. Conversely, the restoration of LATS2 expression abrogates the tumor-promoting effects of forced miR-302/367 cluster expression. Collectively, the potent pluripotency regulator-triggered miR-302/367/LATS2/YAP pathway is essential for prostate tumor-propagating cells and promotes castration resistance. Thus, targeting this signaling axis may represent a promising therapeutic strategy for CRPC.

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