Targeting TAZ Research Articles

Haramine-Mediated Anticancer Effects in Breast Cancer Cells: Targeting TAZ as a Therapeutic Strategy

Haramine-Mediated Anticancer Effects in Breast Cancer Cells: Targeting TAZ as a Therapeutic Strategy

Vascular mimicry as a facilitator of melanoma brain metastasis.

Melanoma has the highest propensity among solid tumors to metastasize to the brain.Melanoma brainmetastases (MBM) are a leading cause of deathinmelanoma and affect 40-60% of patients with late-stagedisease.Therefore, uncovering the molecular mechanisms behind MBM is necessary to enhance therapeutic interventions.Vascular mimicry (VM) is a form of neovascularization linked to invasion, increased risk of metastasis, and poor prognosisin many tumor types, but its significance in MBM remains poorly understood.We found that VM density is elevated in MBM comparedto pairedextracranialspecimensand is associated with tumor volume andCNSedema. In addition, our studies indicate a relevant role of YAP and TAZ, two transcriptional co-factors scarcely studied in melanoma, in tumor cell-vasculogenesis and in brain metastasis. We recently demonstrated activation of the Hippo tumor suppressor pathway and increased degradation of its downstream targets YAP and TAZ in a metastasis impaired cell line model.In the current study we establish the utility of anti-YAP/TAZ therapy in mouse models of metastatic melanoma whereby treatment effectively inhibitsVM andprolongs survival of mice with MBM. The data presented herein suggest that VM may be an important and targetable mechanism in melanoma and that VM inhibition might be useful for treating MBM, an area of high unmet clinical need, thus having important implications for future treatment regimens for these patients.

Abstract 5753: Milk-derived extracellular nanovesicles: A novel delivery strategy for transcriptome targeting therapies in cholangiocarcinoma

Abstract Introduction: Cholangiocarcinoma (CCA) is an aggressive and heterogenous biliary malignancy. Previous therapeutic shortcomings have encouraged the investigation of new strategies, such as targeted therapeutics. YAP/TAZ, transcriptional coactivators of the hippo pathway, have been implicated in the tumorigenesis of CCA along with the Src familiar kinase, LCK. Milk-derived nanovesicles (MNVs) have emerged as a promising biologic delivery apparatus for hepatobiliary malignancy due to their predilection for hepatic uptake. We sought to investigate the utility of aptamer guided MNVs loaded with short interfering RNA (siRNA) targeting YAP, TAZ, and LCK. Methods: MNVs were prepared and loaded with species-specific siRNA prior to decoration with an epithelial cellular adhesion molecule (EpCAM) targeting aptamer. In vitro studies were performed using murine and human CCA cell lines, SB1 and HuCCT-1, respectively. In vivo studies were carried out using C57BL/6 mice following Institutional Animal Care and Use Committee protocols. Results: We previously validated EpCAM as an effective aptamer demonstrated by increased levels of expression in CCA cell lines using immunoblot, RT-PCR and immunofluorescence. Additionally, in vivo experiments demonstrated excellent biodistribution and affinity for tumor-selective uptake. To evaluate knockdown efficacy, CCA cell lines were incubated with EpCAM aptamer guided MNVs individually targeting YAP, TAZ, and LCK which resulted in downregulation of these targets on immunoblot and RT-PCR. MNVs were then loaded with equal concentrations of siRNA targeting YAP, TAZ, and LCK in combination which resulted in similar degrees of gene downregulation compared with single transcriptome targeting MNVs. Due to the role of YAP/TAZ activation in CCA systemic therapy resistance, we investigated the effect of MNVs loaded with either single target or combinatory target siRNA alongside and in combination with gemcitabine and cisplatin (GemCis). Incubation with both combinatory siRNA and GemCis significantly intensified cell death on Pi/Hoechst staining compared with single target knockdown alone. Similar findings were found using separate assays of cell viability, including ATP luminescent quantitation and caspase 3/7 activity. These data suggest MNV transcriptome targeting may induce a state of cell stress which allows for amplification of chemotherapy treatment effect. Conclusion: Aptamer guided, nanovesicle mediated transcriptome targeting is a promising therapeutic strategy in preclinical CCA models that may potentiate chemotherapy response. Our future direction involves further investigating the role of CCA target downregulation and its effect on the tumor immune microenvironment utilizing aptamer guided nanovesicle delivery and inducible knockdown cell lines. Citation Format: Jack W. Sample, Mincheng Yu, Hendrien Kuipers, Danielle M. Carlson, Nathan W. Werneberg, Jennifer L. Tomlinson, Gregory J. Gores, Rory L. Smoot. Milk-derived extracellular nanovesicles: A novel delivery strategy for transcriptome targeting therapies in cholangiocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5753.

Wnt16 Promotes Vascular Smooth Muscle Contractile Phenotype and Function via Taz (Wwtr1) Activation in Male LDLR-/- Mice.

Wnt16 is expressed in bone and arteries, and maintains bone mass in mice and humans, but its role in cardiovascular physiology is unknown. We show that Wnt16 protein accumulates in murine and human vascular smooth muscle (VSM). WNT16 genotypes that convey risk for bone frailty also convey risk for cardiovascular events in the Dallas Heart Study. Murine Wnt16 deficiency, which causes postnatal bone loss, also reduced systolic blood pressure. Electron microscopy demonstrated abnormal VSM mitochondrial morphology in Wnt16-null mice, with reductions in mitochondrial respiration. Following angiotensin-II (AngII) infusion, thoracic ascending aorta (TAA) dilatation was greater in Wnt16-/- vs Wnt16+/+ mice (LDLR-/- background). Acta2 (vascular smooth muscle alpha actin) deficiency has been shown to impair contractile phenotype and worsen TAA aneurysm with concomitant reductions in blood pressure. Wnt16 deficiency reduced expression of Acta2, SM22 (transgelin), and other contractile genes, and reduced VSM contraction induced by TGFβ. Acta2 and SM22 proteins were reduced in Wnt16-/- VSM as was Ankrd1, a prototypic contractile target of Yap1 and Taz activation via TEA domain (TEAD)-directed transcription. Wnt16-/- VSM exhibited reduced nuclear Taz and Yap1 protein accumulation. SiRNA targeting Wnt16 or Taz, but not Yap1, phenocopied Wnt16 deficiency, and Taz siRNA inhibited contractile gene upregulation by Wnt16. Wnt16 incubation stimulated mitochondrial respiration and contraction (reversed by verteporfin, a Yap/Taz inhibitor). SiRNA targeting Taz inhibitors Ccm2 and Lats1/2 mimicked Wnt16 treatment. Wnt16 stimulated Taz binding to Acta2 chromatin and H3K4me3 methylation. TEAD cognates in the Acta2 promoter conveyed transcriptional responses to Wnt16 and Taz. Wnt16 regulates cardiovascular physiology and VSM contractile phenotype, mediated via Taz signaling.

Resistin targets TAZ to promote osteogenic differentiation through PI3K/AKT/mTOR pathway

Osteogenic differentiation (OD) of bone marrow mesenchymal stem cells (BMSCs) contributes significantly to the regeneration of bone defects. Resistin, an adipose tissue-specific secretory factor, has been shown to involve many different functions, including metabolism, inflammation, cancer, and bone remodeling. However, the effects and mechanisms of resistin on OD of BMSCs remain unclear. Herein, we demonstrated that resistin was highly expressed in BMSCs with OD. Upregulation of resistin contributed to the progression of OD of BMSCs by activating PI3K/AKT/mTOR signaling pathway. In addition, resistin facilitated OD by targeting transcriptional co-activator with PDZ-binding motif (TAZ). In a rat femoral condyle bone defect model, local injection of resistin significantly promoted bone repair and improved bone formation. This work contributes to better understanding the mechanism of resistin directly involved in the OD and might provide a new therapeutic strategy for bone defect regeneration.

Abstract 661: Wnt16 Promotes Smooth Muscle Mitochondrial Function And Contractile Phenotype Via Taz (Wwtr1) Relays, Limiting Aneurysmal Dilatation Of Ascending Aorta

Wnt16 is selectively expressed in arterial vascular smooth muscle (VSM) as well as in bone and skin. Non-synonymous WNT16 cSNPs that increase risk for low bone mass also convey risk for composite cardiovascular events (stroke, MI, heart failure, CV death) in the Dallas Heart Study after adjustment for age, sex, ancestry, systolic blood pressure, and body mass index (OR = 1.25, p = 0.02) . To better understand Wnt16’s role in cardiovascular biology, we generated Wnt16-/-;LDLR-/- mice. Blood pressure and pulse wave velocity were reduced in Wnt16-/-;LDLR-/- mice vs. LDLR-/- controls. Ascending aorta (AscAo) dilatation following angiotensin-II (AngII) infusion was worsened with Wnt16 deficiency, while no differences existed at baseline. Contractile markers such as Acta2 - known to convey AscAo aneurysm risk and reduce pressure with genetic deficiency - were down-regulated in Wnt16-/- VSM, with reduction in TGFbeta-induced contraction. De-differentiation markers (C3, Sca1) were upregulated, and mitochondrial respiration (Seahorse oximetry) was significantly impaired with Wnt16 deficiency. Acta2 protein was reduced with Wnt16 deficiency as was aortic Ankrd1, a target of Yap and Taz(Wwtr1) activation via nuclear TEAD-directed transcription. Wnt16-/- VSM exhibited reduced nuclear Yap+Taz. RNAi targeting Wnt16 or Taz (not Yap1 ) phenocopied Wnt16 deficiency, inhibited Wnt16 up-regulation of contractile markers and reversed C3 suppression. Wnt16 deficiency increased the Yap-Taz inhibitory protein Ccm2 in VSM. Moreover, RNAi targeting Yap-Taz inhibitory kinases Lats1/2 or Ccm2 -- but not Ccm3 or Stk3/Stk4 -- elicited responses reciprocal to Wnt16 deficiency. Biotin proximity labeling following expression of Taz-BioID2 fusion protein identified TEAD1, IQGAP3 and specific MAP4K components of the STRIPAK complex as functionally important Wnt16-Taz signaling mediators. TEAD cognates in Acta2 and C3 promoters convey responses to Wnt16 and Taz+Tead1, and Wnt16 treatment increased Taz association with the Acta2 promoter in aortic VSM. Thus, Wnt16 promotes the contractile phenotype and mitochondrial function in VSM and limits AngII aneurysmal remodeling in AscAo. Strategies that augment the VSM Wnt16-Taz relay may mitigate aneurysmal remodeling.

Zinc finger and SCAN domain containing 1, ZSCAN1, is a novel stemness-related tumor suppressor and transcriptional repressor in breast cancer targeting TAZ.

Cancer stem cells (CSCs) targeted therapy holds the potential for improving cancer management; identification of stemness-related genes in CSCs is necessary for its development. The Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) datasets were used for survival analysis. ZSCAN1 correlated genes was identified by Spearman correlation analysis. Breast cancer stem-like cells (BCSLCs) were isolated by sorting CD44+CD24- cells from suspension cultured breast cancer (BC) spheroids. The sphere-forming capacity and sphere- and tumor-initiating capacities were determined by sphere formation and limiting dilution assays. The relative gene expression was determined by qRT-PCR, western blot. Lentivirus system was used for gene manipulation. Nuclear run-on assay was employed to examine the levels of nascent mRNAs. DNA pull-down and Chromatin immunoprecipitation (ChIP) assays were used for determining the interaction between protein and target DNA fragments. Luciferase reporter assay was used for evaluating the activity of the promoter. ZSCAN1 is aberrantly suppressed in BC, and this suppression indicates a bad prognosis. Ectopic expression of ZSCAN1 inhibited the proliferation, clonogenicity, and tumorigenicity of BC cells. ZSCAN1-overexpressing BCSLCs exhibited weakened stemness properties. Normal human mammary epithelial (HMLE) cells with ZSCAN1 depletion exhibited enhanced stemness properties. Mechanistic studies showed that ZSCAN1 directly binds to -951 ~ -925bp region of WWTR1 (encodes TAZ) promoter, inhibits WWTR1 transcription, thereby inhibiting the stemness of BCSCs. Our work thus revealed ZSCAN1 as a novel stemness-related tumor suppressor and transcriptional repressor in BC.

P18.07.A Hippo signaling pathway is strongly involved in meningioma tumorigenesis

Abstract Background Recurrent and aggressive meningiomas remain an unmet medical need in neuro-oncology. In mammals, Hippo signaling pathway is responsible for the growth of organs by regulating cell proliferation and apoptosis. The tumor suppressor NF2 protein belongs to the core of the Hippo pathway and a defect of its gene is present in 50% of meningiomas. Absence of NF2 keeps Hippo pathway inactive allowing the translocation of YAP/TAZ to the nucleus and the formation of a complex with TEADs. This complex then promotes the transcription of anti-apoptotic and proliferative genes such as CTGF, CYR61 and AXL. Here we present experimental results on human meningioma fragments and primary cell cultures supporting that Hippo pathway plays a critical role in meningioma tumorigenesis. Material and Methods The role of the Hippo pathway was studied on 57 meningiomas, well characterized at clinical, histological and molecular level. The genomic profile, target transcripts of the complex YAP/TAZ-TEADs, cell viability, and cell proliferation were analyzed after siRNA transfection targeting YAP, TAZ, YAP+TAZ and TEADs. Results Fifty-seven meningiomas were randomly selected including 27 WHO grade II and III tumors. Thirty (53%) presented a defect on the NF2 gene (NF2def) including 19(65%) grade II/III. NF2def meningiomas presented a significant increase of expression levels of Hippo pathway target transcripts CTGF, CYR61 and AXL in comparison with NF2 wild-type tumors (p<0.0001, p=0.0072 and p=0.0191, respectively). This increase was not correlated with the grade, the sex or with the cerebral localization of the meningiomas. On the other side, IHC analysis suggested this increase was correlated with the nuclear localization of YAP. Disturbing the YAP/TAZ-TEADs complex using siRNA on 10 meningiomas (5 NF2 wild-type and 5 NF2 def) induced a significant decrease on cell proliferation but not on cell viability. This decrease was more important when TAZ was turned off in comparison to turning off of YAP. Conclusion Our experimental results strongly support the importance of the Hippo pathway in meningioma tumorigenesis, supporting its relevance as a new target in meningioma therapy. A.Barlier reports receiving research grants from Inventiva Pharma. No potential conflicts of interest were disclosed by the other authors.

Abstract 562: Altered Hippo Pathway Activity And Impaired Smooth Muscle Contractile Phenotype In Wnt16-Deficient Mice Worsens Ascending Aortic Aneurysm

Wnt16 is expressed in mouse & human vascular smooth muscle (VSM). We assessed the impact of Wnt16 deficiency on angiotensin-II (AngII) -induced aneurysmal remodeling. AngII infusion for 4 weeks increased aortic Wnt16 2-fold & ascending thoracic aorta diameter by 60% (p = 1.5E-4, ANOVA p = 3E-6) in male LDLR-/- mice. Wnt16-/-;LDLR-/- cohorts exhibited worsened aorta dilatation (by 20%; Holm-Sidak p =0.03), indicating a protective role for Wnt16. Wnt16 deficiency reduced both pulse wave velocity & systolic blood pressure (Wnt16-null = 132+/- 3 vs. 146 +/- 6 mmHg, p < 0.05, n =11/genotype), suggesting altered contractile function. Since hypomorphic alleles encoding contractile proteins predispose to ascending aortic aneurysms, we studied the impact of Wnt16 on the contractile phenotype. VSM from Wnt16-null thoracic aorta exhibited reductions in Acta2 & SM22 (protein, mRNA; down 50%, p < 0.05), Myh11 (down 60%; p < 0.05), & Myocardin ( Myocd ; by 65%; p =0.0002). Inhibitory H3K27me3 histone methylation was selectively increased 3-fold in chromatin of genes encoding contractile proteins in Wnt16-/- VSM (p = 3E-5). DNA fragmentation was increased 22% in Wnt16-null VSM (p < 0.01). Label-free quantitative proteomic analyses of aorta revealed (a) upregulation of 14 mechanosensitive LIM proteins in Wnt16-null mice, with (b) > 90% reduction in Ankrd1 - a wound contraction protein & a prototypic target of Yap1-Taz/Wwtr1 activity in the Hippo pathway. Wnt16 deficiency significantly increased VSM cytoplasmic Yap1-Taz protein accumulation while reducing nuclear Yap1-Taz. siRNA targeting Taz, but not Yap1, reduced contractile gene expression, phenocopying the actions of Wnt16 siRNA or genetic deficiency. Antagonism of Lats1/2, Hippo pathway kinases that inhibit Yap1-Taz cytoplasmic-nuclear shuttling, upregulated VSM Myocd (4.4x), Acta2 (1.6x), Ankrd1 (2.5x; p < 0.01), mimicking actions of 8 nM Wnt16 treatment. Dosing mice with Wnt16 (0.25 mg/kg/day, 2 days) upregulated aortic contractile gene expression 1.6- to 1.8-fold (all p < 0.05). Wnt16 limits thoracic aortic remodeling & preserves the VSM contractile phenotype in part via the Hippo - Taz/Wwtr1 signal relay. Strategies that augment Wnt16 activity may mitigate enlargement of ascending aortic aneurysms.

From the Editor’s Desk...

From the Editor’s Desk...

TAZ is indispensable for c-MYC-induced hepatocarcinogenesis

Mounting evidence implicates the Hippo downstream effectors Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) in hepatocellular carcinoma (HCC). We investigated the functional contribution of YAP and/or TAZ to c-MYC-induced liver tumor development. The requirement for YAP and/or TAZ in c-Myc-driven hepatocarcinogenesis was analyzed using conditional Yap, Taz, and Yap;Taz knockout (KO) mice. An hepatocyte-specific inducible TTR-CreERT2 KO system was applied to evaluate the role of YAP and TAZ during tumor progression. Expression patterns of YAP, TAZ, c-MYC, and BCL2L12 were analyzed in human HCC samples. We found that the Hippo cascade is inactivated in c-Myc-induced mouse HCC. Intriguingly, TAZ mRNA levels and activation status correlated with c-MYC activity in human and mouse HCC, but YAP mRNA levels did not. We demonstrated that TAZ is a direct transcriptional target of c-MYC. In c-Myc induced murine HCCs, ablation of Taz, but not Yap, completely prevented tumor development. Mechanistically, TAZ was required to avoid c-Myc-induced hepatocyte apoptosis during tumor initiation. The anti-apoptotic BCL2L12 gene was identified as a novel target regulated specifically by YAP/TAZ, whose silencing strongly suppressed c-Myc-driven murine hepatocarcinogenesis. In c-Myc murine HCC lesions, conditional knockout of Taz, but not Yap, led to tumor regression, supporting the requirement of TAZ for c-Myc-driven HCC progression. TAZ is a pivotal player at the crossroad between the c-MYC and Hippo pathways in HCC. Targeting TAZ might be beneficial for the treatment of patients with HCC and c-MYC activation. The identification of novel treatment targets and approaches for patients with hepatocellular carcinoma is crucial to improve survival outcomes. We identified TAZ as a transcriptional target of c-MYC which plays a critical role in c-MYC-dependent hepatocarcinogenesis. TAZ could potentially be targeted for the treatment of patients with c-MYC-driven hepatocellular carcinoma.

Abstract A24: Functional annotation of the Hippo somatic mutations in human cancer

Abstract The Hippo pathway plays a crucial role in organ size control and tissue homeostasis, whose downstream targets YAP and TAZ are frequently activated in various types of human cancers. However, inactivation of this key tumor suppressor pathway in human cancers has not been fully characterized. In this study, we comprehensively annotate the somatic mutations for 23 Hippo core components in The Cancer Genome Atlas, which includes 11,706 patient samples across 32 major human cancer types. To determine the role of these patient-derived mutations in Hippo pathway regulation, we reconstituted each Hippo component mutant into the corresponding knockout (KO) cells and performed an immunofluorescence screen by using YAP cellular localization as a readout. Through it, we identified a number of somatic mutations that are able to suppress Hippo signaling and activate YAP. In addition, we elucidated the underlying mechanism for several identified somatic mutations and revealed novel regulatory mechanisms for the Hippo pathway. Taken together, our study not only systematically profiled the somatic mutations for the Hippo pathway components, but also generated a valuable resource to further characterize of this key signaling pathway in human cancer development. Citation Format: Han Han, Wenqi Wang. Functional annotation of the Hippo somatic mutations in human cancer [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr A24.

Abstract A41: Inhibition of aberrant YAP and TAZ activity to prevent metastasis formation and growth

Abstract Metastasis causes most cancer-related deaths, and few effective therapies exist for patients with metastatic disease. The development of such therapies requires the identification of proteins essential for the spread and subsequent growth of metastatic cancer cells. Previous work from us and other groups has clearly demonstrated that aberrant YAP or TAZ activity, negatively regulated by the Hippo pathway, promotes cancer development and metastasis. Moreover, many human cancers have abnormally high YAP/TAZ expression or nuclear localization, and this is associated with poor prognosis. We hypothesize that targeting YAP and TAZ or upstream activators will prevent metastasis formation and growth, and we have developed and optimized in vivo model systems to test this. Using these methods, we show that YAP and TAZ are required for metastasis formation in human melanoma and breast cancer cells. An ongoing study using our in vivo metastatic growth assay and inducible YAP/TAZ RNAi is testing if YAP and TAZ are collectively required for metastatic growth after dissemination, and we hope to include the results of this study on our poster. In addition to directly targeting YAP and TAZ, we are also interested in identifying proteins that promote YAP/TAZ activity in metastatic cells, and this could lead to more therapeutic targets. Our recently published work shows that Src signaling can promote YAP/TAZ activity and enhance tumor growth and metastasis. Since integrins promote Src activity and regulate YAP and TAZ, we want to test if there are specific integrins required for YAP/TAZ activity in metastatic cells. Therefore, we used a YAP/TAZ-TEAD transcriptional activity reporter assay to perform an unbiased RNAi screen to identify integrins that regulate YAP/TAZ activity in metastatic melanoma and breast cancer cells. Knockdown of integrin subunits α2, α3, α6, and αV each reduced YAP/TAZ-TEAD transcriptional activity in metastatic breast cancer cells. These results have been confirmed with qPCR for the YAP/TAZ target genes CTGF and CRY61. Interestingly, a different set of integrin subunits appears to be required for YAP/TAZ-TEAD transcriptional activity in metastatic melanoma cells, suggesting the regulation of YAP and TAZ is not the same in different cancer types. Current work aims to use in vivo multiplex metastasis assays, which our lab has developed, to test if knockdown of each integrin either alone, or in combination, prevents metastasis formation and growth. Concurrently, we are focused on elucidating the mechanism by which these integrins enhance YAP/TAZ activity in metastatic cells. Collectively, these studies show the importance of YAP and TAZ and their upstream regulators in metastasis formation and growth and suggest that targeting YAP/TAZ activity may treat metastatic disease. Citation Format: Janine S.A. Warren, Emily Norton, John M. Lamar. Inhibition of aberrant YAP and TAZ activity to prevent metastasis formation and growth [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr A41.

Hsa_circ_0091074 regulates TAZ expression via microRNA‑1297 in triple negative breast cancer cells.

Triple negative breast cancer (TNBC) has the highest recurrence, metastasis and mortality rate of all breast cancer subtypes, due to its typically more aggressive characteristics and lack of effective targeted treatment options. The Hippo pathway is a signaling cascade composed of a group of conserved kinases, which serves an important role in almost all cancer types. Both circular RNAs (circRNAs) and microRNAs (miRNAs) are types of non‑coding RNAs, which influence cancer progression. CircRNAs have been demonstrated to serve as miRNA 'sponges', binding to miRNAs to inhibit their function. In the present study, it was revealed that circular RNA hsa_circ_0091074 binds miR‑1297, and that there is an inverse association between the expression levels of the two non‑coding RNAs in breast cells, indicating that hsa_circ_0091074 may serve as an endogenous 'sponge' for miR‑1297. Subsequently, the potential function and mechanism underlying the involvement of miR‑1297 in breast cancer was investigated via MTT, colony formation, wound healing and cell cycle assays. Increased miR‑1297 expression resulted in a decrease in the protein levels of critical Hippo pathway transcriptional mediator Transcriptional coactivator with PDZ‑binding motif (TAZ), which is a putative target of miR‑1297. This was confirmed using dual‑luciferase reporter assays, which revealed that miR‑1297 targets TAZ by binding its 3'‑untranslated region (3'UTR). The current results indicate that miR‑1297 serves as a suppressor of breast cancer cell proliferation and invasiveness, and that this can be partially reversed by hsa_circ_0091074, suggesting that the hsa_circ_0091074/miR‑1297/TAZ/TEAD4 axis may represent a potential therapeutic target for triple negative breast cancer in the future.

Overexpression of transcriptional co-activator with PDZ-binding motif promotes epithelial mesenchymal transformation of ovarian cancer cells by upregulating Smad3 and Snail1

This study is intended to explore the effect of transcriptional coactivator with PDZ binding motif (TAZ) expression in ovarian cancer cells as well as investigate the expression of signal proteins Smad3 and Snail1. Ovarian cancer cells (SKOV-3) were divided into two groups: control and TAZ overexpression. The overexpression of TAZ in SKOV-3 cells was determined by immunofluorescence, western blot, and qRT-PCR. The proliferation, invasiveness, and expression of epithelial mesenchymal transformation (EMT)-associated proteins were detected, and the expression of Smad3 and Snail1 proteins was determined by qRT-PCR and western blot, respectively. Small interfering RNA (siRNA) targeting TAZ were synthesized and used to transfect SKOV-3. Cell migration and invasion were observed via a wound healing assay and a transwell assay, respectively. The expressions of representative genes involved in proliferation and migration, EMT-associated proteins and Smad3 and Snail1 proteins were also detected by western blot assays. The results of qRT-PCR, immunofluorescence, and western blot showed that, compared with the control group, the expressions of Smad3 and Snail1 protein were upregulated, and the expression of EMT-related genes-including Actin, N-cadherin, and Vimentin protein-was downregulated in the TAZ overexpression group. After TAZ mRNA was suppressed, the migration and invasion ability of the TAZ siRNA group was weaker than that of the control group. In addition, the expression level of Smad3 and Snail1 decreased when TAZ was silenced, while the expression of EMT-related genes increased. Therefore, TAZ in ovarian cancer cells can promote growth, migration, and invasiveness of cancer cells by regulating genes related to proliferation, migration, and invasion.

Yes-associated protein 1 is required for proliferation and function of bovine granulosa cells in vitro†.

Yes-associated protein 1 (YAP1) is a major component of the Hippo signaling pathway. Although the exact extracellular signals that control the Hippo pathway are currently unknown, increasing evidence supports a critical role for the Hippo pathway in embryonic development, regulation of organ size, and carcinogenesis. Granulosa cells (GCs) within the ovarian follicle proliferate and produce steroids and growth factors, which facilitate the growth of follicle and maturation of the oocyte. We hypothesize that YAP1 plays a role in proliferation and estrogen secretion of GCs. In the current study, we examined the expression of the Hippo signaling pathway in bovine ovaries and determined whether it was important for GC proliferation and estrogen production. Mammalian STE20-like protein kinase 1 (MST1) and large tumor suppressor kinase 2 (LATS2) were identified as prominent upstream components of the Hippo pathway expressed in granulosa and theca cells of the follicle and large and small cells of the corpus luteum. Immunohistochemistry revealed that YAP1 was localized to the nucleus of growing follicles. In vitro, nuclear localization of the downstream Hippo signaling effector proteins YAP1 and transcriptional co-activator with PDZ-binding motif (TAZ) was inversely correlated with GC density, with greater nuclear localization under conditions of low cell density. Treatment with verteporfin and siRNA targeting YAP1 or TAZ revealed a critical role for these transcriptional co-activators in GC proliferation. Furthermore, knockdown of YAP1 in GCs inhibited follicle-stimulating hormone (FSH)-induced estradiol biosynthesis. The data indicate that Hippo pathway transcription co-activators YAP1/TAZ play an important role in GC proliferation and estradiol synthesis, two processes necessary for maintaining normal follicle development.

Sal B targets TAZ to facilitate osteogenesis and reduce adipogenesis through MEK-ERK pathway.

Salvianolic acid B (Sal B), a major bioactive component of Chinese herb, was identified as a mediator for bone metabolism recently. The aim of this study is to investigate the underlying mechanisms by which Sal B regulates osteogenesis and adipogenesis. We used MC3T3‐E1 and 3T3‐L1 as the study model to explore the changes of cell differentiation induced by Sal B. The results indicated that Sal B at different concentrations had no obvious toxicity effects on cell proliferation during differentiation. Furthermore, Sal B facilitated osteogenesis but inhibited adipogenesis by increasing the expression of transcriptional co‐activator with PDZ‐binding motif (TAZ). Accordingly, TAZ knock‐down offset the effects of Sal B on cell differentiation into osteoblasts or adipocytes. Notably, the Sal B induced up‐expression of TAZ was blocked by U0126 (the MEK‐ERK inhibitor), rather than LY294002 (the PI3K‐Akt inhibitor). Moreover, Sal B increased the p‐ERK/ERK ratio to regulate the TAZ expression as well as the cell differentiation. In summary, this study suggests for the first time that Sal B targets TAZ to facilitate osteogenesis and reduce adipogenesis by activating MEK‐ERK signalling pathway, which provides evidence for Sal B to be used as a potential therapeutic agent for the management of bone diseases.

IRS-1 targets TAZ to inhibit adipogenesis of rat bone marrow mesenchymal stem cells through PI3K-Akt and MEK-ERK pathways

Gene modification of mesenchymal stem cells (MSCs) offers a promising approach for clinical stem cell therapy. Transcriptional co-activator with PDZ-binding motif (TAZ) plays a vital role in MSCs’ differentiation. We aim to explore the interaction of insulin receptor substrate-1 (IRS-1) with TAZ to regulate MSCs’ adipogenesis in this study. Initially, IRS-1 and TAZ followed similar decreasing expression pattern at the early stage of adipogenesis. And, overexpression of IRS-1 decreased the CCAAT/enhancer binding protein β (C/EBPβ) and peroxi-some proliferator-activated receptor gamma (PPARγ) expression with TAZ upregulation. Accordingly, knockdown of IRS-1 induced the upexpression of C/EBPβ and PPARγ with TAZ downregulation. Indeed, IRS-1 targeted TAZ to downregulate the C/EBPβ and PPARγ expression, while knockdown of TAZ attenuated the IRS-1 inhibited adipogenesis. Furthermore, both LY294002 (the PI3K-Akt inhibitor) and U0126 (the MEK-ERK inhibitor) blocked the regulation of IRS-1 on TAZ during adipogenesis. Additionally, IRS-1 and TAZ influenced the cell proliferation in the above process. Taken together, this study suggests for the first time that IRS-1 is a key regulator of the MSCs’ adipogenesis and may serve as a potential therapeutic target for differential alterations in bone marrow.

Diosgenin inhibited the expression of TAZ in hepatocellular carcinoma

Emerging evidence has supported that TAZ (transcriptional co-activator with PDZ binding motif), one transcription co-activator in Hippo signaling pathway, plays an oncogenic role in liver carcinogenesis. Targeting TAZ could be a potential therapeutic approach for liver cancer patients. In the current study, we aim to determine whether diosgenin could be an inhibitor of TAZ in liver cancer cells. We found that diosgenin inhibited the expression of TAZ in liver cancer cells. Moreover, we found that diosgenin inhibited cell growth, induced apoptosis, suppressed cell migration and invasion in part via inhibition of TAZ in liver cancer cells. Our study provides the evidence to support that diosgenin could be a potential agent for treating human liver cancer.

Targeting TAZ and YAP as a New Therapeutic Approach to Diabetic Nephropathy

Introduction
 Fibrosis is a major contributor to chronic kidney disease (CKD), for which no effective clinical treatment exists. The primary source of fibrosis is the activation of fibroblasts to the myofibroblast state. Fibroblast-myofibroblast transition requires transforming growth factor-β (TGF-β) and its canonical Smad signaling pathway.
 
 Purpose
 Recent findings suggest that mechanical stimuli affect fibroblast behavior. Nuclear localization of YAP/TAZ, closely associated mechanosensitive transcriptional co-factors, are regulated by substrate stiffness. As YAP/TAZ are Smad nuclear retention factors promoting TGF- β signaling, we hypothesized that YAP/TAZ inhibition could attenuate stiffness-mediated, TGF- β induced pro-fibrotic responses.
 
 Methods
 Immunostaining and immunoblotting were used to analyze localization and activity of YAP/TAZ and Smad levels, respectively.
 
 Results
 YAP/TAZ are in an active nuclear location in fibroblasts grown on stiff, fibrotic-like substrates (100kPa). In fibroblasts grown on soft substrates (2kPa), YAP/TAZ are primarily in an inactive cytosolic position. Cells grown on soft surfaces demonstrated strongly attenuated nuclear Smad 2/3 translocation and Smad-3 dependent transcription upon TGF-β stimulation, indicating impaired pro-fibrotic signaling. Verteporfin, a clinically approved drug with YAP inhibitory properties, was used to test the role of YAP/TAZ in reduced TGF-β signaling. Verteporfin reduced TGF-β-induced nuclear Smad2/3 accumulation and Smad3-mediated 
 transcription in fibroblasts grown on stiff surfaces. In vivo, Verteporfin significantly reduces markers of renal fibrosis.
 
 Conclusions
 Soft, healthy kidney-like substrates inhibit, while stiff fibrotic-like substrates promote, pro-fibrotic TGF-β Smad signalling. Verteporfin inactivates the YAP/TAZ fibroblast mechanosensor, reduces stiffness-augmented fibroblast responses to TGF-β through blockade of Smad signalling, and may be a novel anti-fibrotic agent for CKD.