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Aims Methods and Results Conclusion The PEComa family of tumours is defined by spindle/epithelioid cells with myomelanocytic differentiation. A small subset harbours TFE3 fusion; however, YAP1::TEE3 has not been reported. Clear cell stromal tumour of the lung (CCST‐L) is an emerging entity characterized by spindle to epithelioid cells with focal cytoplasmic clearing, inflammatory infiltrates, no myomelanocytic differentiation, and YAP1::TFE3 fusion. Herein, we report two cases of lung tumours with myomelanocytic differentiation that showed inflammatory spindle cell histology, focal epithelioid clear cells, as well as YAP1::TFE3 fusion.The patients were both men, aged 61 and 68 years. The tumours in both cases presented as well‐circumscribed solid masses involving the lung hilum. After lobectomy, no recurrence was observed at 7 and 32 months. Both tumours shared storiform to short fascicular growth of long spindle cells, with a minor component of epithelioid cells showing clear cytoplasm in the background of substantial intratumoral chronic inflammation and dilated blood vessels. One tumour showed focal melanin deposition. Both tumours were immunohistochemically positive for HMB45, Melan A, and h‐caldesmon. Fluorescence in situ hybridization assays indicated the presence of YAP1::TFE3 fusions, which was confirmed by RNA sequencing in one case tested, and by immunohistochemical TFE3 expression and loss of YAP1 C‐terminus staining.We present two cases of inflammatory spindle to epithelioid cell tumours of the lungs with myomelanocytic differentiation and YAP1::TFE3 fusion. This unique morphology and gene fusion suggest that these tumours may constitute a distinct subset of lung PEComa. Furthermore, morphological and molecular overlap with CCST‐L gives rise to a hypothesis of a potential inherent relationship between PEComa and CCST‐L. [ABSTRACT FROM AUTHOR]

Lineage plasticity in small cell lung carcinoma (SCLC) causes therapeutic difficulties. This study aimed to investigate the pathological findings of plasticity in SCLC, focusing on combined SCLC, and elucidate the involvement of YAP1 and other transcription factors. We analysed 100 surgically resected SCLCs through detailed morphological observations and immunohistochemistry for YAP1 and other transcription factors. Component‐by‐component next‐generation sequencing (n = 15 pairs) and immunohistochemistry (n = 35 pairs) were performed on the combined SCLCs. Compared with pure SCLCs (n = 65), combined SCLCs (n = 35) showed a significantly larger size, higher expression of NEUROD1, and higher frequency of double‐positive transcription factors (p = 0.0009, 0.04, and 0.019, respectively). Notably, 34% of the combined SCLCs showed morphological mosaic patterns with unclear boundaries between the SCLC and its partner. Combined SCLCs not only had unique histotypes as partners but also represented different lineage plasticity within the partner. NEUROD1‐dominant combined SCLCs had a significantly higher proportion of adenocarcinomas as partners, whereas POU2F3‐dominant combined SCLCs had a significantly higher proportion of squamous cell carcinomas as partners (p = 0.006 and p = 0.0006, respectively). YAP1 expression in SCLC components was found in 80% of combined SCLCs and 62% of pure SCLCs, often showing mosaic‐like expression. Among the combined SCLCs with component‐specific analysis, the identical TP53 mutation was found in 10 pairs, and the identical Rb1 abnormality was found in 2 pairs. On immunohistochemistry, the same abnormal p53 pattern was found in 34 pairs, and Rb1 loss was found in 24 pairs. In conclusion, combined SCLC shows a variety of pathological plasticity. Although combined SCLC is more plastic than pure SCLC, pure SCLC is also a phenotypically plastic tumour. The morphological mosaic pattern and YAP1 mosaic‐like expression may represent ongoing lineage plasticity. This study also identified the relationship between transcription factors and partners in combined SCLC. Transcription factors may be involved in differentiating specific cell lineages beyond just 'neuroendocrine'. [ABSTRACT FROM AUTHOR]

Atherosclerosis is a leading cause of cardiovascular diseases (CVDs), often resulting in major adverse cardiovascular events (MACEs), such as myocardial infarction and stroke due to the rupture or erosion of vulnerable plaques. Ferroptosis, an iron‐dependent form of cell death, has been implicated in the development of atherosclerosis. Despite its involvement in CVDs, the specific role of ferroptosis in atherosclerotic plaque stability remains unclear. In this study, we confirmed the presence of ferroptosis in unstable atherosclerotic plaques and demonstrated that the ferroptosis inhibitor ferrostatin‐1 (Fer‐1) stabilizes atherosclerotic plaques in apolipoprotein E knockout (Apoe−/−) mice. Using bioinformatic analysis combining RNA sequencing (RNA‐seq) with single‐cell RNA sequencing (scRNA‐seq), we identified Yes‐associated protein 1 (YAP1) as a potential key regulator of ferroptosis in vascular smooth muscle cells (VSMCs) of unstable plaques. In vitro, we found that YAP1 protects against oxidized low‐density lipoprotein (oxLDL)‐induced ferroptosis in VSMCs. Mechanistically, YAP1 exerts its anti‐ferroptosis effects by regulating the expression of glutaminase 1 (GLS1) to promote the synthesis of glutamate (Glu) and glutathione (GSH). These findings establish a novel mechanism where the inhibition of ferroptosis promotes the stabilization of atherosclerotic plaques through the YAP1/GLS1 axis, attenuating VSMC ferroptosis. Thus, targeting the YAP1/GLS1 axis to suppress VSMC ferroptosis may represent a novel strategy for preventing and treating unstable atherosclerotic plaques. [ABSTRACT FROM AUTHOR]

Cells have an incredible ability to physically interact with neighboring cells and their environment. They can detect and respond to mechanical forces by converting mechanical stimuli into biochemical signals in a process known as mechanotransduction. This is a key process for the adaption of vascular smooth muscle and endothelial cells to altered flow and pressure conditions. Mechanical stimuli, referring to a physical force exerted on cells, are primarily sensed by transmembrane proteins and the actin cytoskeleton, which initiate a cascade of intracellular events, including the activation of signaling pathways, ion channels, and transcriptional regulators. Recent work has highlighted an important role of the transcriptional coactivators YAP/TAZ for mechanotransduction in vascular cells. Interestingly, the activity of YAP/TAZ decreases with age, providing a potential mechanism for the detrimental effects of aging in the vascular wall. In this review, we summarize the current knowledge on the functional role of YAP and TAZ in vascular endothelial and smooth muscle cells for mechanotransduction in homeostasis and disease. In particular, the review is focused on in vivo observations from conditional knockout (KO) models of YAP/TAZ and the potential implications these studies may have for our understanding of vascular disease development. [ABSTRACT FROM AUTHOR]

Stromal interaction molecule 1 (STIM1) is the endoplasmic reticulum Ca2+ sensor for store‐operated calcium entry and is closely associated with carcinogenesis and tumor progression. Previously, we found that STIM1 is upregulated in melanoma cells resistant to the serine/threonine‐protein kinase B‐raf inhibitor vemurafenib, although the mechanism underlying this upregulation is unknown. Here, we show that vemurafenib resistance upregulates STIM1 through an epidermal growth factor (EGF)/epidermal growth factor receptor (EGFR)‐Yes‐associated protein 1 (YAP1)/TEA domain transcription factor 2 (TEAD2) signaling axis. Vemurafenib resistance can lead to an increase in EGF and EGFR levels, causing activation of the EGFR signaling pathway, which promotes YAP1 nuclear localization to increase the expression of STIM1. Our findings not only reveal the mechanism by which vemurafenib resistance promotes STIM1 upregulation, but also provide a rationale for combined targeting of the EGF/EGFR‐YAP1/TEAD2‐STIM1 axis to improve the therapeutic efficacy of BRAF inhibitor in melanoma patients. [ABSTRACT FROM AUTHOR]

The multidomain protein BAG3 exerts pleiotropic oncogenic functions in many tumor entities including glioblastoma (GBM). Here, we compared BAG3 protein–protein interactions in either adherently cultured or stem‐like cultured U251 GBM cells. In line with BAG3's putative role in regulating stem‐like properties, identified interactors in sphere‐cultured cells included different stem cell markers (SOX2, OLIG2, and NES), while interactomes of adherent BAG3‐proficient cells indicated a shift toward involvement of BAG3 in regulation of cilium assembly (ACTR3 and ARL3). Applying a set of BAG3 deletion constructs we could demonstrate that none of the domains except the WW domain are required for suppression of cilia formation by full‐length BAG3 in U251 and U343 cells. In line with the established regulation of the Hippo pathway by this domain, we could show that the WW mutant fails to rescue YAP1 nuclear translocation. BAG3 depletion reduced activation of a YAP1/AURKA signaling pathway and induction of PLK1. Collectively, our findings point to a complex interaction network of BAG3 with several pathways regulating cilia homeostasis, involving processes related to ciliogenesis and cilium degradation. [ABSTRACT FROM AUTHOR]

Breast cancer antiestrogen resistance 4 (BCAR4) has been suggested that can modulate cell behavior, resulting in tumorigenesis and chemoresistance. However, the underlying mechanisms of BCAR4 in trastuzumab resistance (TR) is still elusive. Here, we explored the function and the underlying mechanism of BCAR4 involving in TR. We found that BCAR4 is significantly upregulated in trastuzumab‐resistant BC cells. Knockdown of BCAR4 could sensitize the BC cells to trastuzumab and suppress epithelial–mesenchymal transition (EMT). Mechanically, BCAR4 promotes yes‐associated protein 1 (YAP1) expression by competitively sponging miR‐665, to activated TGF‐β signaling. Reciprocally, YAP1 could occupy the BCAR4 promoter to enhance its transcription, suggesting that there exists a positive feedback regulation between YAP1 and BCAR4. Targeting the BCAR4/miR‐665/YAP1 axis may provide a novel insight of therapeutic approaches for TR in BC. [ABSTRACT FROM AUTHOR]

Cholesterol metabolism has important roles in maintaining membrane integrity and countering the development of diseases such as obesity and cancers. Cancer cells sustain cholesterol biogenesis for their proliferation and microenvironment reprograming even when sterols are abundant. However, efficacy of targeting cholesterol metabolism for cancer treatment is always compromised. Here it is shown that CSN6 is elevated in HCC and is a positive regulator of hydroxymethylglutaryl‐CoA synthase 1 (HMGCS1) of mevalonate (MVA) pathway to promote tumorigenesis. Mechanistically, CSN6 antagonizes speckle‐type POZ protein (SPOP) ubiquitin ligase to stabilize HMGCS1, which in turn activates YAP1 to promote tumor growth. In orthotopic liver cancer models, targeting CSN6 and HMGCS1 hinders tumor growth in both normal and high fat diet. Significantly, HMGCS1 depletion improves YAP inhibitor efficacy in patient derived xenograft models. The results identify a CSN6‐HMGCS1‐YAP1 axis mediating tumor outgrowth in HCC and propose a therapeutic strategy of targeting non‐alcoholic fatty liver diseases‐ associated HCC. [ABSTRACT FROM AUTHOR]

Porocarcinomas are rare sweat gland cancers representing the malignant counterpart to benign poromas. Their diagnosis can be challenging, especially in the absence of an associated poroma or when the tumor is poorly differentiated. Since recurrent YAP1::MAML2 and YAP1::NUTM1 fusions have been identified in poroid tumors, molecular studies provide an opportunity to support the diagnosis in challenging cases. We describe a case of a female patient in her early 90s, with a polypoid mass of the hip. Histopathologically, there was a poorly differentiated malignant spindle cell tumor adjacent to a poroma. Because of the close association with a poroma and immunoreactivity for p40, a diagnosis of spindle cell porocarcinoma was rendered, which was further supported by YAP1 immunohistochemical studies. Antibodies targeting both the N‐terminus and C‐terminus confirmed YAP1 rearrangement in both the poroma and the spindle cell neoplasm. Subsequent targeted RNA sequencing revealed a YAP1::MAML3 gene fusion. MAML3 has previously not yet been reported as a YAP1 fusion partner in porocarcinoma. With the illustration of a rare spindle cell variant of porocarcinoma and the identification of a novel gene fusion, this case report expands the spectrum of morphologic and genomic aberrations associated with porocarcinoma. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to investigate the clinical and prognostic relevance of the Hippo‐YAP transactivators YAP1 and TAZ in oral squamous cell carcinoma, and their possible relationship with PI3K/mTOR pathway activation. Materials and Methods: Immunohistochemical analysis of YAP1, TAZ, PIK3CA (p110α), p‐AKT (Ser473), and p‐S6 (Ser235) was performed in paraffin‐embedded tissue specimens from 165 OSCC patients. Correlations between protein expression and clinical data were further assessed. Results: YAP1 expression was detected in both cytoplasm and nucleus of tumor cells, whereas TAZ expression was only found in the nucleus. Nuclear YAP1 was significantly associated with tumor size (p = 0.03), neck lymph node metastasis (p = 0.02), TNM stage (p = 0.02), and poor differentiation (p = 0.04). Nuclear TAZ was associated with tobacco (p = 0.03) and alcohol consumption (p = 0.04), and poor tumor differentiation (p = 0.04). There was a positive significant correlation between nuclear and cytoplasmic YAP1, nuclear TAZ, p110α expression, and mTORC1 activation p‐S6 (S235). Combined expression of nuclear and cytoplasmic YAP1 was prognostic in both univariate and multivariate analyses. Active nuclear YAP1 was significantly and independently associated with poor disease‐specific (p = 0.005, HR = 2.520; 95% CI = 1.319–4.816) and overall survival (p = 0.015, HR = 2.126; 95% CI = 1.155–3.916). Conclusion: Nuclear YAP1 is an independent predictor of poor survival in oral squamous cell carcinoma. [ABSTRACT FROM AUTHOR]

The interplay between immune cells/macrophages and fibroblast‐like synoviocytes (FLSs) plays a pivotal role in initiating synovitis; however, their involvement in metabolic disorders, including diabetic osteoarthritis (DOA), is largely unknown. In this study, single‐cell RNA sequencing (scRNA‐seq) is employed to investigate the synovial cell composition of DOA. A significant enrichment of activated macrophages within eight distinct synovial cell clusters is found in DOA synovium. Moreover, it is demonstrated that increased glycolysis in FLSs is a key driver for DOA patients' synovial macrophage infiltration and polarization. In addition, the yes‐associated protein 1 (YAP1)/thioredoxin‐interacting protein (TXNIP) signaling axis is demonstrated to play a crucial role in regulating glucose transporter 1 (GLUT1)‐dependent glycolysis in FLSs, thereby controlling the expression of a series of adhesion molecules such as intercellular adhesion molecule‐1 (ICAM‐1) which may subsequently fine‐tune the infiltration of M1‐polarized synovial macrophages in DOA patients and db/db diabetic OA mice. For treatment, M1 macrophage membrane‐camouflaged Verteporfin (Vt)‐loaded PLGA nanoparticles (MVPs) are developed to ameliorate DOA progression by regulating the YAP1/TXNIP signaling axis, thus suppressing the synovial glycolysis and the infiltration of M1‐polarized macrophages. The results provide several novel insights into the pathogenesis of DOA and offer a promising treatment approach for DOA. [ABSTRACT FROM AUTHOR]

Poroma is a benign sweat gland tumour showing morphological features recapitulating the superficial portion of the eccrine sweat coil. A subset of poromas may transform into porocarcinoma, its malignant counterpart. Poroma and porocarcinoma are characterised by recurrent gene fusions involving YAP1, a transcriptional co‐activator, which is controlled by the Hippo signalling pathway. The fusion genes frequently involve MAML2 and NUTM1, which are also rearranged in other cutaneous and extracutaneous neoplasms. We aimed to review the clinical, morphological and molecular features of this category of adnexal neoplasms with a special focus upon emerging differential diagnoses, and discuss how their systematic molecular characterisation may contribute to a standardisation of diagnosis, more accurate classification and, ultimately, refinement of their prognosis and therapeutic modalities. [ABSTRACT FROM AUTHOR]

Laminin332 is a glycoprotein consisting of α3/β3/γ2 chains, of which the γ2 chain (Ln‐γ2) is expressed in tumor cells at the invasive front in many types of malignant tumors. We have previously reported that Ln‐γ2 is associated with tumor invasion of cutaneous squamous cell carcinoma (cSCC) in vivo and in vitro. Recently, tumor budding (TB; invasion patterns in small clusters of less than five cancer cells in the stroma at the invasive front) has been reported to be a risk factor for lymph node metastasis in cSCC. Based on these findings, we speculated that expression of Ln‐γ2 is related to TB in cSCC and would be an invasive factor that causes lymph node metastasis. In this study, we investigated the relationship between Ln‐γ2 expression and clinicopathological findings, including TB, in 102 cases of cSCC using immunohistochemistry. The results showed that high expression of Ln‐γ2 at the invasive front correlated with a high TB score. In addition, high Ln‐γ2 expression at the invasive front was also associated with lymphatic invasion, lymph node metastasis, and poor prognosis (death or recurrence), as in TB. Furthermore, we showed a positive association between Ln‐γ2 expression at the invasive front and Yes‐associated protein (YAP) expression in the Hippo pathway. Our results suggest that Ln‐γ2 expression at the invasive front may have a role in TB formation via YAP and contribute to prognosis by causing lymphatic invasion and lymph node metastasis. The expression of Ln‐γ2 would be useful for risk assessment of lymph node metastasis and poor prognosis in routine practice of cSCC. [ABSTRACT FROM AUTHOR]

Aims: Metaplastic thymoma is a rare thymic tumour characterized by Yes Associated Protein 1 (YAP1) and Mastermind Like Transcriptional Coactivator 2 (MAML2) gene fusions resulting from an intrachromosomal inversion of chromosome 11. Immunohistochemistry with an antibody directed against the C‐terminus of YAP1 has shown loss of expression in YAP1‐rearranged vascular neoplasms, poromas, and porocarcinomas. This study aimed to validate an anti‐YAP1 C‐terminal antibody as an ancillary immunohistochemical marker for the diagnosis of metaplastic thymoma. Materials and methods: Ten metaplastic thymomas were selected for the current study. Fluorescence in situ hybridization (FISH), next‐generation sequencing (NGS), and reverse transcription‐polymerase chain reaction (RT‐PCR) analyses were performed to detect YAP1::MAML2 fusions. We then performed immunohistochemistry to detect YAP1 C‐terminus expression in 10 metaplastic thymomas, 50 conventional thymomas (10 each of type A thymoma, type AB thymoma, type B1 thymoma, type B2 thymoma, and type B3 thymoma) and seven thymic carcinomas. Results: All 10 cases showed narrow split signals with a distance of nearly two signal diameters and sometimes had false‐negative results in YAP1 and MAML2 break‐apart FISH (BA‐FISH). Abnormal colocalized signals of the YAP1::MAML2 fusion were observed in all 10 cases using fusion FISH (F‐FISH) assays. Eight of 10 cases with adequate nucleic acids were successfully sequenced and all showed YAP1::MAML2 fusions; in two cases the fusions were detected by both DNA and RNA sequencing and in six cases by RNA sequencing only. YAP1::MAML2 fusion transcripts were identified in four cases by RT‐PCR. Metaplastic thymoma showed loss of YAP1 C‐terminus expression in all 10 (100%) cases. All other thymic neoplasms showed retained YAP1 C‐terminus expression. Conclusion: YAP1 C‐terminus immunohistochemistry is a highly sensitive and specific ancillary marker that distinguishes metaplastic thymoma from its mimics. BA‐FISH assays could not effectively detect YAP1::MAML2 fusions due to the proximity of the two genes. Loss of YAP1 C‐terminus expression is a reliable surrogate for the detection of YAP1::MAML2 fusions in metaplastic thymoma. [ABSTRACT FROM AUTHOR]

Background: Gastric cancer (GC) is one of the most common tumours in East Asia countries and is associated with Helicobacter pylori infection. H. pylori utilizes virulence factors, CagA and VacA, to up‐regulate pro‐inflammatory cytokines and activate NF‐κB signaling. Meanwhile, the PIEZO1 upregulation and cancer‐associated fibroblast (CAF) enrichment were found in GC progression. However, the mechanisms of PIEZO1 upregulation and its involvement in GC progression have not been fully elucidated. Methods: The CAF enrichment and clinical significance were investigated in animal models and primary samples. The expression of NF‐κB and PIEZO1 in GC was confirmed by immunohistochemistry staining, and expression correlation was analysed in multiple GC datasets. GSEA and Western blot analysis revealed the YAP1‐CTGF axis regulation by PIEZO1. The stimulatory effects of CTGF on CAFs were validated by the co‐culture system and animal studies. Patient‐derived organoid and peritoneal dissemination models were employed to confirm the role of the PIEZO1‐YAP1‐CTGF cascade in GC. Results: Both CAF signature and PIEZO1 were positively correlated with H. pylori infection. PIEZO1, a mechanosensor, was confirmed as a direct downstream of NF‐κB to promote the transformation from intestinal metaplasia to GC. Mechanistic studies revealed that PIEZO1 transduced the oncogenic signal from NF‐κB into YAP1 signaling, a well‐documented oncogenic pathway in GC progression. PIEZO1 expression was positively correlated with the YAP1 signature (CTGF, CYR61, and c‐Myc, etc.) in primary samples. The secreted CTGF by cancer cells stimulated the CAF infiltration to form a stiffened collagen‐enrichment microenvironment, thus activating PIEZO1 to form a positive feedback loop. Both PIEZO1 depletion by shRNA and CTGF inhibition by Procyanidin C1 enhanced the efficacy of 5‐FU in suppressing the GC cell peritoneal metastasis. Conclusion: This study elucidates a novel driving PIEZO1‐YAP1‐CTGF force, which opens a novel therapeutic avenue to block the transformation from precancerous lesions to GC. H. pylori‐NF‐κB activates the PIEZO1‐YAP1‐CTGF axis to remodel the GC microenvironment by promoting CAF infiltration. Targeting PIEZO1‐YAP1‐CTGF plus chemotherapy might serve as a potential therapeutic option to block GC progression and peritoneal metastasis. [ABSTRACT FROM AUTHOR]

Myocardial fibrosis post myocardial infarction (MI) is characterized by abnormal extracellular matrix (ECM) deposition and cardiac dysfunction could finally develop into serious heart disease, like heart failure. Lots of regulating factors involved in this pathological process have been reported while the specific mediators and underlying mechanisms remain to need to be further investigated. As part of the NAP1 family, Nucleosome assembly protein 1 like 1 (NAP1L1) is expressed in a wide variety of tissues. Here, we report that NAP1L1 is a significant regulator of cardiac fibrosis and is upregulated in ischemic cardiomyopathy patient hearts. Enhanced expression of NAP1L1 can promote cardiac fibroblasts (CFs) proliferation, migration, and differentiation into myofibroblasts. In contrast, loss of NAP1L1 decreased fibrosis‐related mRNA and protein levels, inhibited the trans‐differentiation, and blunted migration and proliferation of CFs after Transforming Growth Factorβ1（TGF‐β1）stimulation. In vivo, NAP1L1 knockout mice enhanced cardiac function and reduced fibrosis area in response to MI stimuli. Mechanically, NAP1L1 binding to Yes‐associated protein 1 (YAP1) protein influences its stability, and silencing NAP1L1 can inhibit YAP1 expression by promoting its ubiquitination and degradation in CFs. Collectively, NAP1L1 could potentially be a new therapeutic target for various cardiac disorders, including myocardial fibrosis. [ABSTRACT FROM AUTHOR]

Poromatosis is a rare condition characterized by the development of multiple poromas, mainly reported in patients with a history of malignancy. Recently, frequent YAP1::MAML2 and YAP1::NUTM1 fusions have been described in poromas and porocarcinomas. To date, the molecular features of poromatosis have been investigated in one patient only, wherein the poromas harbored YAP1::MAML2 fusions. Herein, we present two additional cases of poromatosis with YAP1::MAML2 fusions. Case 1: An 81‐year‐old woman presented with nine papules on the scalp, trunk, and extremities persisting for a year. She had a history of breast cancer, with no information on the treatment. Seven papules were excised. Case 2: A 65‐year‐old woman presented with 21 lesions on her trunk and lower extremities persisting for 2 years. She had been diagnosed with breast cancer 11 years prior and had undergone partial mastectomy, radiotherapy, chemotherapy, and endocrine therapy. Four lesions were excised. All 11 lesions in both patients were histopathologically similar: anastomosing cords and strands extending from the epidermis, and poroid and cuticular cell proliferation with interspersed small ducts. The tumors showed diffuse nuclear expression of YAP1 N‐terminus and loss of YAP1 C‐terminus expression. No lesions showed NUT immunopositivity. Sanger sequencing identified YAP1::MAML2 fusions in the poromas of both patients. [ABSTRACT FROM AUTHOR]

Background: MicroRNAs (miRNAs) play crucial regulatory roles in cancer progression, including oral cancer (OC). However, the biological mechanisms of miRNA‐15a‐5p in OC remain unclear. This study aimed to evaluate the expression of miRNA‐15a‐5p and the YAP1 gene in OC. Methods: A total of 22 clinically and histologically confirmed oral squamous cell carcinoma (OSCC) patients were recruited, and their tissues were stored in a stabilizing solution. Later, RT‐PCR was performed to evaluate miRNA‐15a‐5p and the targeting gene YAP1. The results of OSCC samples were compared with unpaired normal tissues. Results: The normality tests, Kolmogorov–Smirnov and Shapiro–Wilk, revealed a normal distribution. Inferential statistics were performed using an independent sample t‐test/unpaired t‐test among the study intervals to compare the expression of miR‐15a and YAP1. SPSS (IBM SPSS Statistics for Windows, Version 26.0, Armonk, NY: IBM Corp. Released 2019) was used to analyse the data. The significance level was set at 5% (α = 0.05), and a p‐value <0.05 was considered statistically significant. The expression of miRNA‐15a‐5p was lower in OSCC than in normal tissue, whereas the opposite was observed for YAP1 levels. Conclusion: In conclusion, this study demonstrated that miRNA‐15a‐5p was downregulated and YAP1 was overexpressed, which had a statistically significant difference between the normal and OSCC groups. Therefore, miRNA‐15a‐5p may serve as a novel biomarker to better understand the pathology and as a potential target in OSCC therapy. [ABSTRACT FROM AUTHOR]

Background: Osteosarcoma (OS) is a fatal adolescent tumor, which is susceptible to remote metastases at an early stage, and its treatment remains a major challenge. ubiquitin‐specific protease 10 (USP10) is primarily located in the cytoplasm and can therefore deubiquitinate various cytoplasmic proteins. However, the expression and mechanism of USP10 in OS remain ambiguous. The aim of this study was to explore how USP10 affects Yes‐associated protein1 (YAP1) to influence the metastasis and epithelial–mesenchymal transition (EMT). Methods: Western blotting, qRT‐PCR, and immunohistochemical (IHC) analyses were performed to evaluate USP10 and YAP1 levels. Using wound healing and transwell tests, the roles and molecular pathways of USP10 and YAP1 ability to migrate and invade of OS were investigated, and cell morphological alterations were examined using phalloidin staining. Results: Our results indicated that USP10, a new type of deubiquitinating protease, is increased in OS tissues and cells contrasted with adjacent healthy tissues. Overexpression of USP10 correlated with tumor size, distant metastasis, and TNM stage, and was an independent factor of poor prognosis in OS patients. Also, USP10 expression is closely connected with the incident of OS metastasis and tumor size. Functional assays revealed that USP10 knockdown suppressed cell migrating and invading ability and inhibited the EMT of OS cells in vivo and in vitro. In addition, we showed that USP10 knockdown decreased the levels of YAP1, which is an important positive regulator of migration and invasion in many cancers. We also found a significant positive correlation between USP10 and YAP1 levels, further demonstrating that USP10‐induced migration and EMT are based on YAP1 in OS cells. In a mechanistic way, USP10 stabilizes the expression of YAP1 by mediating its deubiquitination in OS cells. Conclusion: Together, this study showed that USP10 can directly interact with YAP1 to reduce ubiquitinated YAP1, thereby stabilizing its protein levels and affecting EMT and distant metastasis in OS cells. [ABSTRACT FROM AUTHOR]

Bone remodeling is vital to the maintenance of bone homeostasis and may lead to destructive skeletal diseases once the balance is disrupted. Crosstalk between Wnt and estrogen receptor (ER) signaling has been proposed in bone remodeling, but the underlying mechanism remains unclear. This study was designed to explore the effect of Wnt-ER signaling during the osteogenic differentiation of bone marrow stromal cells (BMSCs). Rat BMSCs were isolated and identified using flow cytometry and stimulated with Wnt3a. Wnt3a treatment promoted osteogenic differentiation and mineralization of the BMSCs. Meanwhile, Wnt3a enhanced the expression of ERa as well as the canonical Wnt signaling mediator β-catenin and the alternativeWnt signaling effector Yesassociated protein 1 (YAP1). Interestingly, DNA pulldown assay revealed direct binding of transcriptional enhanced associate domain 1 (TEAD1) and lymphoid enhancer binding factor 1 (LEF1), transcriptional partners of YAP1 and β-catenin, respectively, to the promoter region of ERa. In addition, inhibition of TEAD1 and LEF1 suppressed Wnt3-promoted BMSC osteogenic differentiation and blocked Wnt3a-induced ERa expression. Furthermore, an in vivo model of femoral bone defect also supported that Wnt3a facilitated bone healing in an ERa-dependent way. Together, we suggest thatWnt3a promotes the osteogenic activity of BMSCs through YAP1 and β-catenin-dependent activation of ERa, via direct binding of TEAD1 and LEF1 to the ERa promoter. [ABSTRACT FROM AUTHOR]

Aims: Recently, YAP1 fusion genes have been demonstrated in eccrine poroma and porocarcinoma, and the diagnostic use of YAP1 immunohistochemistry has been highlighted in this setting. In other organs, loss of YAP1 expression can reflect YAP1 rearrangement or transcriptional repression, notably through RB1 inactivation. In this context, our objective was to re‐evaluate the performance of YAP1 immunohistochemistry for the diagnosis of poroma and porocarcinoma. Methods and results: The expression of the C‐terminal part of the YAP1 protein was evaluated by immunohistochemistry in 543 cutaneous epithelial tumours, including 27 poromas, 14 porocarcinomas and 502 other cutaneous tumours. Tumours that showed a lack of expression of YAP1 were further investigated for Rb by immunohistochemistry and for fusion transcripts by real‐time PCR (YAP1::MAML2 and YAP1::NUTM1). The absence of YAP1 expression was observed in 24 cases of poroma (89%), 10 porocarcinoma (72%), 162 Merkel cell carcinoma (98%), 14 squamous cell carcinoma (SCC) (15%), one trichoblastoma and one sebaceoma. Fusions of YAP1 were detected in only 16 cases of poroma (n = 66%), 10 porocarcinoma (71%) all lacking YAP1 expression, and in one sebaceoma. The loss of Rb expression was detected in all cases except one of YAP1‐deficient SCC (n = 14), such tumours showing significant morphological overlap with porocarcinoma. In‐vitro experiments in HaCat cells showed that RB1 knockdown resulted in repression of YAP1 protein expression. Conclusion: In addition to gene fusion, we report that transcriptional repression of YAP1 can be observed in skin tumours with RB1 inactivation, including MCC and a subset of SCC. [ABSTRACT FROM AUTHOR]

The efficacy of anti‐PD‐1 therapy is not as expected in hepatocellular carcinoma (HCC). YAP1 was overexpressed and activated in HCC. The mechanism of YAP1 in HCC immune escape is unclear. Anti‐PD‐1 treatment increased YAP1 expression in liver tumor cells, and exhausted CD4+ and CD8+ T cells in the blood and spleen of liver tumor mice. YAP1 knockdown suppressed PD‐L1 expression, which was involved in JAK1/STAT1, 3 pathways. Moreover, Yap1 knockout elevated CD4+ and CD8+ T cells in liver tumor niche. Consistently, verteporfin, YAP1 inhibitor, decreased TGF‐β and IFN‐γ in liver tumor niche and exhausted CD8+ T cell in the spleen. DHA suppressed YAP1 expression and break immune evasion in liver tumor niche, characterized by decreased PD‐L1 in liver tumor cells and increased CD8+ T cell infiltration. Furthermore, DHA combined with anti‐PD‐1 treatment promoted CD4+ T cell infiltration in the spleen and CD8+ T cell in tumor tissues of mice. In summary, YAP1 knockdown in liver tumor cells suppressed PD‐L1 expression and recruited cytotoxic T lymphocytes (CTLs), leading to break immune evasion in tumor niche. Mechanistically, YAP1 knockdown suppressed PD‐L1 expression, which was involved in JAK1/STAT1, 3 pathways. Finally, DHA inhibited YAP1 expression, which not only inhibited liver tumor proliferation but also break the immunosuppressive niche in liver tumor tissues and improve the effect of anti‐PD‐1 therapy. [ABSTRACT FROM AUTHOR]

While several computational methods have been developed to predict the functional relevance of phosphorylation sites, experimental analysis of the interdependency between protein phosphorylation and Protein–Protein Interactions (PPIs) remains challenging. Here, we describe an experimental strategy to establish interdependencies between protein phosphorylation and complex formation. This strategy is based on three main steps: (i) systematically charting the phosphorylation landscape of a target protein; (ii) assigning distinct proteoforms of the target protein to different protein complexes by native complex separation (AP‐BNPAGE) and protein correlation profiling; and (iii) analyzing proteoforms and complexes in cells lacking regulators of the target protein. We applied this strategy to YAP1, a transcriptional co‐activator for the control of organ size and tissue homeostasis that is highly phosphorylated and among the most connected proteins in human cells. We identified multiple YAP1 phosphosites associated with distinct complexes and inferred how both are controlled by Hippo pathway members. We detected a PTPN14/LATS1/YAP1 complex and suggest a model how PTPN14 inhibits YAP1 via augmenting WW domain‐dependent complex formation and phosphorylation by LATS1/2. Synopsis: A novel approach is proposed to study the functional relationships between two critical mechanisms in cell signaling: PTMs and complex formation. This proteomic workflow is applied to investigate YAP1, a major signal integrator and effector of the Hippo pathway. Modules of YAP1 phospho‐proteoforms and their interactors were identified via AP‐BNPAGE.A causal relationship between site phosphorylation and complex formation was established.The control of YAP1 phosphorylation and complex formation was studied in cells lacking known pathway effectors.A model was developed to demonstrate how PTPN14 could inhibit YAP1 co‐transcriptional activity via augmenting ternary complex formation and phosphorylation by LATS1/2. [ABSTRACT FROM AUTHOR]

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive and fatal disease, with most patients succumbing within 1-2 years despite undergoing multiple treatments. Androgen-receptor (AR) inhibitors, including enzalutamide (ENZ), are used for the treatment of mCRPC; however, most patients develop resistance to ENZ. Herein, we propose that the repression of SLC22A3 by AR-V7/YAP1/TAZ conferred ENZ resistance in mCRPC. SLC22A3 expression is specifically downregulated in the ENZ-resistant C4-2B MDVR cells, and when YAP1/TAZ is hyperactivated by AR full-length or AR-V7, these proteins interact with DNMT1 to repress SLC22A3 expression. We observed low SLC22A3 expression and high levels of TAZ or YAP1 in mCRPC patient tissues harbouring AR-V7 and the opposite expression patterns in normal patient tissues. Our findings suggest a mechanism underlying ENZ resistance by providing evidence that the AR-V7/YAP1/TAZ axis represses SLC22A3, which could be a potential treatment target in prostate cancer. [ABSTRACT FROM AUTHOR]

Accumulating evidence has underscored the importance of the Hippo‐YAP1 signaling in lung tissue homeostasis, whereas its deregulation induces tumorigenesis. YAP1 and its paralog TAZ are the key downstream effectors tightly controlled by the Hippo pathway. YAP1/TAZ exerts oncogenic activities by transcriptional regulation via physical interaction with TEAD transcription factors. In solid tumors, Hippo‐YAP1 crosstalks with other signaling pathways such as Wnt/β‐catenin, receptor tyrosine kinase cascade, Notch and TGF‐β to synergistically drive tumorigenesis. As YAP1/TAZ expression is significantly correlated with unfavorable outcomes for the patients, small molecules have been developed for targeting YAP1/TAZ to get a therapeutic effect. In this review, we summarize the recent findings on the deregulation of Hippo‐YAP1 pathway in nonsmall cell lung carcinoma, discuss the molecular mechanisms of its dysregulation in leading to tumorigenesis, explore the therapeutic strategies for targeting YAP1/TAZ, and provide the research directions for deep investigation. We believe that detailed delineation of Hippo‐YAP1 regulation in tumorigenesis provides novel insight for accurate therapeutic intervention. [ABSTRACT FROM AUTHOR]

Tyrosine kinase inhibitors (TKIs) that target the ROS proto‐oncogene 1, receptor tyrosine kinase (ROS1) gene have shown dramatic therapeutic effects in patients with ROS1‐rearranged non‐small‐cell lung cancer (NSCLC). Nevertheless, advanced ROS1‐rearranged NSCLC is rarely cured as a portion of the tumor cells can survive the initial stages of ROS1‐TKI treatment, even after maximum tumor shrinkage. Therefore, understanding the mechanisms underlying initial cell survival during ROS1‐TKI treatment is necessary to prevent cell survival and achieve a cure for ROS1‐rearranged NSCLC. In this study, we clarified the initial survival mechanisms during treatment with lorlatinib, a ROS1 TKI. First, we established a patient‐derived ezrin gene‐ROS1‐rearranged NSCLC cell line (KTOR71). Then, following proteomic analysis, we focused on yes‐associated protein 1 (YAP1), which is a major mediator of the Hippo pathway, as a candidate factor involved in cell survival during early lorlatinib treatment. Yes‐associated protein 1 was activated by short‐term lorlatinib treatment both in vitro and in vivo. Genetic inhibition of YAP1 using siRNA, or pharmacological inhibition of YAP1 function by the YAP1‐inhibitor verteporfin, enhanced the sensitivity of KTOR71 cells to lorlatinib. In addition, the prosurvival effect of YAP1 was exerted through the reactivation of AKT. Finally, combined therapy with verteporfin and lorlatinib was found to achieve significantly sustained tumor remission compared with lorlatinib monotherapy in vivo. These results suggest that YAP1 could mediate initial cell resistance to lorlatinib in KTOR71 cells. Thus, combined therapy targeting both YAP1 and ROS1 could potentially improve the outcome of ROS1‐rearranged NSCLC. [ABSTRACT FROM AUTHOR]

This study aimed to reveal the prognostic role of the Hippo pathway in different histopathological subtypes of renal cell carcinoma (RCC). The TCGA‐KIRC (n = 537), TCGA‐KIRP (n = 291) and TCGA‐KICH (n = 113), which contain data about clear cell (ccRCC), papillary (pRCC) and chromophobe RCC (chRCC), respectively, were investigated. Gene Set Variation Analysis was used to compare the activity of many pathways within a single sample. Oncogenic pathway‐related expression differed between cases of ccRCC involving low and high Hippo pathway activity. There were two subsets of ccRCC, in which the cancer exhibited lower and higher Hippo signalling activity, respectively, compared with normal tissue. In the ccRCC cohort, lower Hippo pathway activity was associated with a higher clinical stage (p < 0.001). The Hippo pathway (HR = 0.29; 95% CI = 0.17–0.50, p < 0.001), apoptosis (HR = 6.02; 95% CI = 1.47–24.61; p = 0.013) and the p53 pathway (HR = 0.09; 95% CI = 0.02–0.36; p < 0.001) were identified as independent prognostic factors for ccRCC. The 5‐year overall survival of the ccRCC patients with low and high Hippo pathway activity were 51.9% (95% CI = 45.0–59.9) and 73.6% (95% CI = 67.8–79.9), respectively. In conclusion, the Hippo pathway plays an important role in the progression of ccRCC. Low Hippo pathway activity is associated with poor outcomes in ccRCC, indicating the tumour suppressor function of this pathway. [ABSTRACT FROM AUTHOR]

Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumor with dismal prognosis. Recently, molecular subtypes of SCLC have been defined by the expression status of ASCL1, NEUROD1, YAP1, and POU2F3 transcription regulators. ASCL1 is essential for neuroendocrine differentiation and is expressed in the majority of SCLC. Although previous studies investigated ASCL1 target genes in SCLC cells, ASCL1‐mediated regulation of miRNAs and its relationship to molecular subtypes remain poorly explored. Here, we performed genome‐wide profiling of chromatin modifications (H3K27me3, H3K4me3, and H3K27ac) by CUT&Tag assay and ASCL1 knockdown followed by RNA sequencing and miRNA array analyses in SCLC cells. ASCL1 could preferentially regulate genes associated with super‐enhancers (SEs) defined by enrichment of H3K27ac marking. Moreover, ASCL1 positively regulated several SE‐associated miRNAs, such as miR‐7, miR‐375, miR‐200b‐3p, and miR‐429, leading to repression of their targets, whereas ASCL1 suppressed miR‐455‐3p, an abundant miRNA in other molecular subtypes. We further elucidated unique patterns of SE‐associated miRNAs in different SCLC molecular subtypes, highlighting subtype‐specific miRNA networks with functional relevance. Notably, we found apparent de‐repression of common target genes of different miRNAs following ASCL1 knockdown, suggesting combinatorial action of multiple miRNAs underlying molecular heterogeneity of SCLC (e.g., co‐targeting of YAP1 by miR‐9 and miR‐375). Our comprehensive analyses provide novel insights into SCLC pathogenesis and a clue to understanding subtype‐dependent phenotypic differences. [ABSTRACT FROM AUTHOR]

Rhabdomyosarcoma (RMS), a cancer characterized by features of skeletal muscle, is the most common soft-tissue sarcoma of childhood. With 5-year survival rates among high-risk groups at < 30%, new therapeutics are desperately needed. Previously, using a myoblast-based model of fusion-negative RMS (FN-RMS), we found that expression of the Hippo pathway effector transcriptional coactivator YAP1 (YAP1) permitted senescence bypass and subsequent transformation to malignant cells, mimicking FN-RMS. We also found that YAP1 engages in a positive feedback loop with Notch signaling to promote FN-RMS tumorigenesis. However, we could not identify an immediate downstream impact of this Hippo-Notch relationship. Here, we identify a HES1-YAP1-CDKN1C functional interaction, and show that knockdown of the Notch effector HES1 (Hes family BHLH transcription factor 1) impairs growth of multiple FN-RMS cell lines, with knockdown resulting in decreased YAP1 and increased CDKN1C expression. In silico mining of published proteomic and transcriptomic profiles of human RMS patient-derived xenografts revealed the same pattern of HES1-YAP1-CDKN1C expression. Treatment of FN-RMS cells in vitro with the recently described HES1 small-molecule inhibitor, JI130, limited FN-RMS cell growth. Inhibition of HES1 in vivo via conditional expression of a HES1-directed shRNA or JI130 dosing impaired FN-RMS tumor xenograft growth. Lastly, targeted transcriptomic profiling of FN-RMS xenografts in the context of HES1 suppression identified associations between HES1 and RAS-MAPK signaling. In summary, these in vitro and in vivo preclinical studies support the further investigation of HES1 as a therapeutic target in FN-RMS. [ABSTRACT FROM AUTHOR]

Bladder cancer (BlC) is the fourth most common cancer in males worldwide, but few systemic chemotherapy options for its effective treatment exist. The development of new molecularly‐targeted agents against BlC is therefore an urgent issue. The Hippo signaling pathway, with its upstream LATS kinases and downstream transcriptional co‐activators YAP1 and TAZ, plays a pivotal role in diverse cell functions, including cell proliferation. Recent studies have shown that overexpression of YAP1 occurs in advanced BlCs and is associated with poor patient prognosis. Accessing data from our previous screening of a chemical library of compounds targeting the Hippo pathway, we identified DMPCA (N‐(3,4‐dimethoxyphenethyl)‐6‐methyl‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐amine) as an agent able to induce the phosphorylation of LATS1 and YAP1/TAZ in BlC cells, thereby suppressing their viability both in vitro and in mouse xenografts. Our data indicate that DMPCA has a potent anti‐tumor effect, and raise the possibility that this agent may represent a new and effective therapeutic option for BlC. [ABSTRACT FROM AUTHOR]

Diabetic kidney disease (DKD) is well‐acknowledged as one of the most common complications in diabetes mellitus. Recent studies have demonstrated the promising role of mesenchymal stem cell‐derived exosomes (MSC‐exos) as a cell‐free treatment strategy for DKD. The present study sought to investigate the therapeutic potential and the underlying mechanisms of MSC‐exos in DKD. The authentication of MSC‐exos was validated by western blot, transmission electron microscope (TEM), and nanosight tracking analysis (NTA). Apoptosis was detected by western blot, TUNEL staining, and flow cytometry. Epithelial‐to‐mesenchymal transition (EMT) was evaluated by western blot and immunofluorescence. The relationship between miR‐424‐5p and Yes‐associated protein 1 (YAP1) was revealed by dual luciferase reporter assay. We observed that MSC‐exos could attenuate DKD by decreasing cell apoptosis and inhibiting epithelial‐to‐mesenchymal transition (EMT) in diabetic kidneys in db/db mice. Besides, we documented that MSC‐exos could reverse high glucose‐induced apoptosis and EMT in HK2 cells. Interestingly, miR‐424‐5p derived from MSC‐exos could inhibit YAP1 activation in HK2 cells, resulting in alleviation of high glucose‐induced cell apoptosis and EMT. Our study provides novel insights into MSC‐exos‐mediated protective effect in DKD. MSC‐exos could inhibit high glucose‐induced apoptosis and EMT through miR‐424‐5p targeting of YAP1. [ABSTRACT FROM AUTHOR]

Background: Poromas, and their malignant counterparts, porocarcinomas, harbor recurrent translocations involving YAP1‐MAML2, YAP1‐NUTM1, and infrequently WWTR1‐NUTM1; YAP1‐NUTM1 being the most common in porocarcinomas. NUT immunohistochemistry (IHC) can be used to identify NUTM1‐translocated tumors. This study sought to investigate potential novel NUTM1‐fusion partners among NUT IHC‐positive poromas and porocarcinomas. Methods: Thirteen NUT IHC‐positive poroid tumors (four poromas and nine porocarcinomas) were identified within a multi‐institutional international cohort. Next‐generation sequencing (NGS) assessed for NUTM1 fusion partners. Results: NGS detected a NUTM1 fusion in 12 of 13 cases: YAP1‐NUTM1 (11/12 cases) and WWTR1‐NUTM1 (1/12 cases). Two of the cases (2/12) with NUTM1 fusion were not called by the NGS algorithm but had at least one read‐spanning YAP1‐NUTM1 break point upon manual review. A NUTM1 fusion was not identified in one case; however, the sample had low RNA quality. The following fusion events were identified: YAP1 exon 4::NUTM1 exon 3 in six cases, YAP1 exon 6::NUTM1 exon 2 in one case, YAP1 exon 3::NUTM1 exon 3 in three cases, WWTR1 exon 3::NUTM1 exon 3 in one case, and YAP1 exon 8::NUTM1 exon 3 fusion in one case. Conclusion: While no novel NUTM1 fusion partners were identified within our cohort, 12 of 13 cases had discoverable NUTM1 fusions; YAP1‐NUTM1 fusion was detected in 11 cases (92%) and WWTR1‐NUTM1 in 1 case (8%). These data corroborate findings from other recent investigations and further substantiate the utility of NUT IHC in diagnosing a subset of poroid neoplasms. In addition, two of our cases harbored fusions of YAP1 exon 6 to NUTM1 exon 3 and YAP1 exon 8 to NUTM1 exon 2, which have not been reported before in poroid neoplasms and indicate novel break points of YAP1. [ABSTRACT FROM AUTHOR]

Disc herniation is a kind of disease caused by degenerative discs, which is common in the elderly, bringing substantial financial burden to families and society. Mechanical tension has a vital effect on the maintenance of cartilage function, however, the molecular mechanism by which mechanical tension causes degenerative discs to remain unclear. This study was the first to reveal Yes‐associated protein 1(YAP1) is a key regulator in mechanical tension‐mediated degenerative discs. Activation of YAP1 may be a valuable strategy to delays the degeneration of human cartilage chondrocytes. We found that YAP1 expression was significantly decreased in degenerative human endplate cartilage and tissue with the strength and time of mechanical stimulation, but the cell cycle distribution was significantly changed under the 10% cyclic mechanical tension(CMT). Besides, the degeneration of endplate cartilage can be delayed by activating the expression level of YAP1 in vitro and it has also been verified in the cartilage endplate tissue in vitro. Furthermore, We found that YAP1 and TEAD1 overexpression increased the activity of the ACAN or COL2A1 promoter to enhance the transcriptional activity of human chondrocyte collagen. The CMT activates the classic Hippo signaling pathway of YAP1, and piezo1 may regulate YAP1 expression through the Hippo signaling pathway. In conclusion, these results suggest the novel mechanism of YAP contributes to delaying the degeneration of endplate cartilage and targeting YAP in combination with Piezo1 is a potential therapeutic approach for the treatment of endplate cartilage degeneration. [ABSTRACT FROM AUTHOR]

Ankyrin repeat and KH domain‐containing protein 1, ANKHD1, has been identified as a regulator of signaling pathways and cellular processes of relevance in carcinogenesis. However, the role of ANKHD1 in breast cancer remains unclear. The aim of the present study was to characterize the expression pattern and involvement of ANKHD1 in the malignant phenotype of breast cancer cell lines and to investigate the clinical relevance of ANKHD1 in a breast cancer context. Gene and protein expressions were assessed in the cell lines by quantitative reverse transcription PCR and Western blot analysis, respectively, and ANKHD1 silencing through siRNA transfection was conducted for further in vitro functional assays. The expression of ANKHD1 was identified in non‐tumorigenic breast epithelium and breast cancer cell lines, but differences in cellular localization were found among the neoplasia subtypes. ANKHD1 silencing reduced the viability, clonogenicity, and migration of triple‐negative breast cancer (TNBC) cells. Bioinformatics analyses demonstrated that patients with triple‐negative basal‐like 2 and mesenchymal breast cancer subtypes had high ANKHD1 expression associated with poor recurrence‐free survival. Therefore, these data indicate that ANKHD1 relevance in breast cancer varies among its subtypes, indicating the importance of ANKHD1 in TNBC. [ABSTRACT FROM AUTHOR]

Aims: Clear cell stromal tumour of the lung (CCST‐L) is a rare, recently recognised neoplasm which has been found to express TFE3 and harbour YAP1::TFE3 fusions. Initial data suggested a benign process; however, a single reported case gave rise to distant metastases. We sought to describe the clinicopathological and molecular features of additional cases of CCST‐L. Methods and Results: Pathology and molecular archives were searched for cases of CCST‐L or tumours with YAP1::TFE3 fusions. Clinical features were noted. Available slides, including immunohistochemical studies, were re‐reviewed for diagnosis confirmation and assessment of pathological features. Results of molecular studies were also recorded. Four tumours were identified, all occurring in women (median age = 61 years, range = 24–69). Median tumour size was 4.4 cm (range = 1–9.5 cm); three tumours were unifocal and one was multifocal. Tumours were composed of epithelioid to spindled cells with eosinophilic to clear cytoplasm and grew in sheets, vague nests and short fascicles. Nuclear atypia was predominately mild; however, two cases showed scattered atypical cells. Mitotic activity was generally low, although one case showed a mitotic count of 6/2 mm2. All tumours expressed TFE3 and harboured YAP1::TFE3 fusions. One case was unresectable and was treated with chemotherapy, and two underwent complete resection. One patient died of disease 7 months following diagnosis, while a second patient was alive with no evidence of disease after 43 months. Follow‐up was not available for two cases. Conclusion: CCST‐L expresses TFE3, harbours YAP1::TFE3 fusions and at least rare cases behave in an aggressive manner. [ABSTRACT FROM AUTHOR]

The tissue distribution and prognostic relevance of subtype‐specific proteins (ASCL1, NEUROD1, POU2F3, YAP1) present an evolving area of research in small‐cell lung cancer (SCLC). The expression of subtype‐specific transcription factors and P53 and RB1 proteins were measured by immunohistochemistry (IHC) in 386 surgically resected SCLC samples. Correlations between subtype‐specific proteins and in vitro efficacy of various therapeutic agents were investigated by proteomics and cell viability assays in 26 human SCLC cell lines. Besides SCLC‐A (ASCL1‐dominant), SCLC‐AN (combined ASCL1/NEUROD1), SCLC‐N (NEUROD1‐dominant), and SCLC‐P (POU2F3‐dominant), IHC and cluster analyses identified a quadruple‐negative SCLC subtype (SCLC‐QN). No unique YAP1‐subtype was found. The highest overall survival rates were associated with non‐neuroendocrine subtypes (SCLC‐P and SCLC‐QN) and the lowest with neuroendocrine subtypes (SCLC‐A, SCLC‐N, SCLC‐AN). In univariate analyses, high ASCL1 expression was associated with poor prognosis and high POU2F3 expression with good prognosis. Notably, high ASCL1 expression influenced survival outcomes independently of other variables in a multivariate model. High POU2F3 and YAP1 protein abundances correlated with sensitivity and resistance to standard‐of‐care chemotherapeutics, respectively. Specific correlation patterns were also found between the efficacy of targeted agents and subtype‐specific protein abundances. In conclusion, we investigated the clinicopathological relevance of SCLC molecular subtypes in a large cohort of surgically resected specimens. Differential IHC expression of ASCL1, NEUROD1, and POU2F3 defines SCLC subtypes. No YAP1‐subtype can be distinguished by IHC. High POU2F3 expression is associated with improved survival in a univariate analysis, whereas elevated ASCL1 expression is an independent negative prognosticator. Proteomic and cell viability assays of human SCLC cell lines revealed distinct vulnerability profiles defined by transcription regulators. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Loss of FXR, one of bile acid receptors, enlarged livers. Yes‐associated protein 1 (YAP1), a dominant oncogene, promotes hepatocellular carcinoma (HCC). However, the relationship between FXR and YAP1 was unspecified in bile acid homeostasis in HCC. Here, we used TIMER2.0, the Cancer Genome Atlas (TCGA) Database, and Kaplan–Meier Plotter Database and discovered that FXR was positively correlated with better prognosis in liver cancer patients. Our previous research showed that dihydroartemisinin (DHA) inhibited cell proliferation in HepG2 and HepG22215 cells. However, the relationship of YAP1 and the bile acid receptor FXR remains elusive during DHA treatment. Furthermore, we showed that DHA improved FXR and reduced YAP1 in the liver cancer cells and mice. Additionally, the expression of nucleus protein FXR was enhanced in Yap1LKO mice with liver cancer. DHA promoted the expression level of whole and nuclear protein FXR independent of YAP1 in Yap1LKO mice with liver cancer. DHA declined cholesterol 7α‐hydroxylase, but not sterol 27‐hydroxylase, and depressed cholic acid and chenodeoxycholic acid of liver tissue in Yap1LKO mice with liver cancer. Generally, our results suggested that DHA improved FXR and declined YAP1 to suppress bile acid metabolism. Thus, we suggested that FXR acted as a potential therapeutic target in HCC. [ABSTRACT FROM AUTHOR]

Yes‐associated protein (YAP) is a major component of the Hippo pathway involved in development, growth, repair and homeostasis. Nonsense YAP1 mutations in humans result in autosomal dominant coloboma. Here, we generated a conditional knockout mouse model in which Yap1 was specifically deleted in embryonic retinal progenitor cells (RPCs) and in mature Müller cells using a Chx10‐Cre driver. Our data demonstrated that the conditional ablation of Yap1 in embryonic RPCs does not prevent normal retinal development and caused no gross changes in retinal structure during embryonic and early postnatal life. Nevertheless, Yap1 deficient in retinal Müller cells in adult mice leads to impaired visual responses and extensive late‐onset retinal degeneration, characterized by reduced cell number in all retinal layers. Immunofluorescence data further revealed the degeneration and death of rod and cone photoreceptors, bipolar cells, horizontal cells, amacrine cells and ganglion cells to varying degrees in aged knockout mice. Moreover, alteration of glial homeostasis and reactive gliosis were also observed. Finally, cell proliferation and TUNEL assay revealed that the broad retinal degeneration is mainly caused by enhanced apoptosis in late period. Together, this work uncovers that YAP is essential for the normal vision and retinal maintenance, highlighting the crucial role of YAP in retinal function and homeostasis. [ABSTRACT FROM AUTHOR]

Background: Hydrogen peroxide (H2O2) is a key reactive oxygen species (ROS) generated during appendage regeneration among vertebrates. However, its role during tail regeneration in axolotl as redox signaling molecule is unclear. Results: Treatment with exogenous H2O2 rescues inhibitory effects of apocynin‐induced growth suppression in tail blastema cells leading to cell proliferation. H2O2 also promotes recruitment of immune cells, regulate the activation of AKT kinase and Agr2 expression during blastema formation. Additionally, ROS/H2O2 regulates the expression and transcriptional activity of Yap1 and its target genes Ctgf and Areg. Conclusions: These results show that H2O2 is necessary and sufficient to promote tail regeneration in axolotls. Additionally, Akt signaling and Agr2 were identified as ROS targets, suggesting that ROS/H2O2 is likely to regulate epimorphic regeneration through these signaling pathways. In addition, ROS/H2O2‐dependent‐Yap1 activity is required during tail regeneration. [ABSTRACT FROM AUTHOR]

Cholangiocarcinoma (CCA) is a severe malignancy originating from the bile duct and the second most common primary liver cancer. NF‐kappa B interacting lncRNA (NKILA) is a functional lncRNA, which play important role in human cancers. However, the role and underlying mechanism of NKILA in CCA remains largely unknown. Here, our study demonstrated that NKILA was significantly upregulated in CCA tissues and cells. Overexpression of NKILA is associated with advanced TNM stage, lymph node and distant metastasis, and also indicated poor prognosis in CCA patients. Functionally, NKILA facilitated CCA growth and metastasis in vitro and in vivo. The 5‐methylcytosine (m5C) methyltransferase NSUN2 interacts with NKILA, increasing its m5C level and promoting its interaction with YBX1. Moreover, NKILA physically interacted with and suppressed miR‐582‐3p, which was regulated by METTL3‐mediated N6‐methyladenosine (m6A) modification. Finally, we showed that YAP1 was a target of NKILA via miR‐582‐3p and NKILA functioned partially via YAP1 in CCA. Taken together, our findings indicate a novel regulatory mechanism of NKILA for promoting CCA progression and that NKILA may be a promising target for CCA treatment. [ABSTRACT FROM AUTHOR]

Yes‐associated protein 1 (YAP1) interacts with TEAD transcription factor in the nucleus and upregulates TEAD‐target genes. YAP1 is phosphorylated by large tumor suppressor (LATS) kinases, the core kinases of the Hippo pathway, at 5 serine residues and is sequestered and degraded in the cytoplasm. In human cancers with the dysfunction of the Hippo pathway, YAP1 becomes hyperactive and confers malignant properties to cancer cells. We have observed that cold shock induces protein kinase C (PKC)‐mediated phosphorylation of YAP1. PKC phosphorylates YAP1 at 3 serine residues among LATS‐mediate phosphorylation sites. Importantly, PKC activation recruits YAP1 to the cytoplasm even in LATS‐depleted cancer cells and reduces the cooperation with TEAD. PKC activation induces promyelocytic leukemia protein‐mediated SUMOylation of YAP1. SUMOylated YAP1 remains in the nucleus, binds to p73, and promotes p73‐target gene transcription. Bryostatin, a natural anti‐neoplastic reagent that activates PKC, induces YAP1/p73‐mediated apoptosis in cancer cells. Bryostatin reverses malignant transformation caused by the depletion of LATS kinases. Therefore, bryostatin and other reagents that activate PKC are expected to control cancers with the dysfunction of the Hippo pathway. [ABSTRACT FROM AUTHOR]

The emerging role of FERM domain‐containing protein 6 (FRMD6) in cancer progression has been revealed in several malignancies. However, its relevance on thyroid cancer is not well understood. This work evaluated the possible role and mechanism of FRMD6 in thyroid cancer. We demonstrated that FRMD6 expression was downregulated in thyroid cancer by analyzing the Cancer Genome Atlas data. Remarkable reductions in FRMD6 expression were also confirmed in the clinical specimens and cell lines of thyroid cancer. The upregulation of FRMD6 restrained the proliferation, epithelial–mesenchymal transition, and invasion of thyroid cancer. Moreover, FRMD6 overexpression significantly increased the apoptosis and cell cycle arrest. Further molecular research demonstrated that the overexpression of FRMD6 increased the phosphorylation levels of mammalian STE20‐like protein kinase 1, large tumor suppressor 1, and Yes‐associated protein 1 (YAP1) and prohibited the activation of YAP1. The re‐expression of constitutively active YAP1 strikingly reversed FRMD6‐induced tumor‐inhibiting effects. Thyroid cancer cells overexpressing FRMD6 had a weakened ability to form xenograft tumors in vivo in nude mice. Overall, the overexpression of FRMD6 produces remarkable tumor‐inhibiting effects in thyroid cancer by inhibiting oncogenic YAP1. [ABSTRACT FROM AUTHOR]

Ras protein activator like 2 (RASAL2) has a cancer‐related function, but plays inconsistent roles in different malignancies. This project was designed to determine the role of RASAL2 in carcinogenesis in gastric cancer. The Cancer Genome Atlas data revealed high levels of RASAL2 in gastric cancer tissue, which was confirmed in clinical specimens of gastric cancer via real‐time quantitative PCR and western blotting assays. High RASAL2 was correlated with a reduced survival rate in gastric cancer patients. In gastric cancer cell lines, the silencing of RASAL2 restrained cellular proliferation, invasion and epithelial‐to‐mesenchymal transition, while enhancing chemosensitivity to cisplatin. Mechanistically, the silencing of RASAL2 was found to inhibit the activation of Yes‐associated protein 1 (YAP1), a pro‐oncogenic protein in gastric cancer, and decrease the expression of YAP1 target genes. The re‐expression of constitutively active YAP1 substantially reversed RASAL2‐silencing‐produced antitumor effects. Moreover, treatment with YAP1 inhibitors could diminish RASAL2‐overexpression‐evoked oncogenic effects in gastric cancer cells. Additionally, gastric cancer cells with RASAL2 silencing exhibited a reduced ability to form xenograft tumors in nude mice. Collectively, our data demonstrate that the silencing of RASAL2 has noteworthy antitumor effects in gastric cancer cells via the suppression of YAP1 activation. This project underscores a vital role of the RASAL2/YAP1 axis in gastric progression and indicates that targeting this oncogenic axis may be applied as a potential therapeutic option for gastric cancer. [ABSTRACT FROM AUTHOR]

Aims: Clear cell (haemangioblastoma‐like) stromal tumour of the lung is a newly described, rare pulmonary neoplasm. Recurrent YAP1–TFE3 gene fusions have recently been reported in three cases. We describe two additional cases and confirm the characteristic YAP1–TFE3 gene fusion. Methods and results: Two mesenchymal tumours of lung were identified from our soft tissue pathology consultation services and RNA sequencing was performed. Both cases were in male patients, aged 35 and 77 years. Both presented as solitary lung nodules measuring 3.9 and 7.5 cm in greatest dimension. Histopathologically, the tumours were composed of epithelioid to plump spindle cells arranged in packets and solid sheets. The cells showed fusiform to ovoid nuclei with open chromatin, variably prominent nucleoli and scant to moderate, clear to eosinophilic cytoplasm. Cytological atypia and significant mitotic activity were minimal. None of the tumours expressed lineage‐specific immunophenotypical markers. Both cases were diffusely positive for nuclear TFE3. Unlike YAP1–TFE3‐fused epithelioid haemangioendothelioma, for which the fusion breakpoint occurs in YAP1 exon 1 and TFE3 exons 4 or 6, the fusion breakpoints of these tumours were located in YAP1 exon 4 and TFE3 exon 7. Following complete surgical resection, neither of the tumours has recurred or metastasised (follow‐up period 6–7 months). Conclusions: We validate the presence of YAP1–TFE3 gene fusion in a unique primary mesenchymal tumour of lung, adding additional support for clear cell stromal tumour of the lung as a distinct entity. [ABSTRACT FROM AUTHOR]

Background and Aims: Epidemiological studies have shown direct associations between type 2 diabetes and the risk of cancers. Accumulating evidence indicates that metformin is profoundly implicated in preventing tumor development. However, the exact mechanism underlying the antitumor effects of metformin in hepatocellular carcinoma (HCC) is still not clear. Methods: In this study, we investigated the effects of metformin on a mouse HCC model and interleukin‐22 (IL‐22)‐associated carcinogenesis in vitro. Results: We found that metformin significantly suppressed the incidence and tumor burden of HCC in the diethyl‐nitrosamine‐induced HCC mouse model. As expected, the expression of IL‐22, an important factor involved in HCC progression, was markedly reduced by metformin. Treatment of HCC cells with metformin inhibited IL‐22 induced cell proliferation, migration, and invasion, and promoted cell apoptosis. Furthermore, ectopic expression of IL‐22 makes HCC more aggressive, whereas metformin largely compromised it in vitro and in vivo. Mechanistically, the whole transcriptome analysis and functional analysis revealed that Hippo signaling pathway was involved in the antitumor ability of metformin. Consistent with this, metformin directly inhibited LATS1/2 and activated Mst1/2, phosphorylated YAP1 in vitro. After blocking the Hippo pathway by XMU‐MP‐1, the inhibitor of MST1/2, the inhibitory effects by metformin were dramatically attenuated as shown by in vitro study. Conclusions: Collectively, our findings illuminate a new regulatory mechanism, metformin activates Hippo signaling pathway to regulate IL‐22 mediated HCC progression and provide new insights into its tumor‐suppressive roles. [ABSTRACT FROM AUTHOR]

High‐grade neuroendocrine carcinoma of gynecologic origin (NEC‐GYN) is a highly aggressive cancer that often affects young women. The clinical management of NEC‐GYN is typically extrapolated from its counterpart, small cell carcinoma of the lung (SCLC), but, unfortunately, available therapies have limited benefit. In our NEC‐GYN cohort, median progression‐free survival (PFS) and overall survival (OS) were 1 and 12 months, respectively, indicating the highly lethal nature of this cancer. Our comprehensive genomic analyses unveiled that NEC‐GYN harbors a higher mutational burden with distinct mutational landscapes from SCLC. We identified 14 cancer driver genes, including the most frequently altered KMT2C (100%), KNL1 (100%), NCOR2 (100%), and CCDC6 (93%) genes. Transcriptomic analysis identified several novel gene fusions; astonishingly, the MALAT1 lincRNA gene was found in ˜ 20% of all fusion events in NEC‐GYN. Furthermore, NEC‐GYN exhibited a highly immunosuppressive state, intact RB1 expression, and was uniquely enriched with the YAP1high molecular subtype. Our study identifies several potential therapeutic targets and suggests an urgent need to re‐evaluate the treatment options for NEC‐GYN. [ABSTRACT FROM AUTHOR]

Neuroendocrine prostate cancer (NEPC) is a rare but aggressive histologic variant of prostate cancer that responds poorly to androgen deprivation therapy. Hybrid NEPC‐adenocarcinoma (AdCa) tumors are common, often eluding accurate pathologic diagnosis and requiring ancillary markers for classification. We recently performed an outlier‐based meta‐analysis across a number of independent gene expression microarray datasets to identify novel markers that differentiate NEPC from AdCa, including up‐regulation of insulinoma‐associated protein 1 (INSM1) and loss of Yes‐associated protein 1 (YAP1). Here, using diverse cancer gene expression datasets, we show that Hippo pathway‐related genes, including YAP1, are among the top down‐regulated gene sets with expression of the neuroendocrine transcription factors, including INSM1. In prostate cancer cell lines, transgenic mouse models, and human prostate tumor cohorts, we confirm that YAP1 RNA and YAP1 protein expression are silenced in NEPC and demonstrate that the inverse correlation of INSM1 and YAP1 expression helps to distinguish AdCa from NEPC. Mechanistically, we find that YAP1 loss in NEPC may help to maintain INSM1 expression in prostate cancer cell lines and we further demonstrate that YAP1 silencing likely occurs epigenetically, via CpG hypermethylation near its transcriptional start site. Taken together, these data nominate two additional markers to distinguish NEPC from AdCa and add to data from other tumor types suggesting that Hippo signaling is tightly reciprocally regulated with neuroendocrine transcription factor expression. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Angiomotin‐like 1 (AMOTL1) is reportedly a pivotal tumor‐associated protein that is strongly associated with the tumorigenesis of multiple malignant tumors. However, the issue of whether AMOTL1 plays a role in the tumorigenesis of glioma remains unclear. The aim of this work was to explore the possible relationship between AMOTL1 and glioma progression. Results demonstrated that high levels of AMOTL1 in glioma tissues were associated with a reduced survival rate in patients with glioma. Cellular functional assays revealed that silencing of AMOTL1 in glioma cell lines substantially decreased cell proliferation and invasion and increased cell apoptosis. Further investigation revealed that silencing of AMOTL1 inhibited the activation of yes‐associated protein 1 (YAP1) and decreased the expression of YAP1 target genes. Reactivation of YAP1 reversed AMOTL1‐silencing‐induced antitumor effects, whereas inhibition of YAP1 abolished AMOTL1‐overexpression‐induced tumor‐promoting effects in glioma cells. Silencing of AMOTL1 also retarded the growth of glioma cell‐derived xenograft tumors in vivo. In conclusion, these findings suggested that AMOTL1 may exert a tumor‐promoting function in glioma by enhancing the activation of YAP1 signaling. This work suggested AMOTL1 as a potential target for the development of antiglioma therapy. [ABSTRACT FROM AUTHOR]

The suppressive roles of Fat1 have been widely revealed in various tumors. However, its effects on the tumor‐initiating ability of nonsmall cell lung cancer (NSCLC) cells have never been elucidated. Currently, we identified that a higher level of Fat1 mRNA expression predicted a longer overall survival and first‐progression survival of lung cancer patients, especially in adenocarcinoma patients. In addition, Fat1 mRNA exhibited a lower level in lung cancer tissues relative to that in normal tissues. Functionally, we focused on the effects of Fat1 on the tumor‐initiating ability of NSCLC cells and we found that Fat1 overexpression decreased the expression of tumor‐initiating markers. Furthermore, overexpression of Fat1 reduced ALDH1 activity and sphere‐formation ability of NSCLC cells. Mechanistically, we revealed that Fat1 promoted the nuclear‐cytoplasmic transportation of YAP1 (Yes‐associated protein 1), a critical executor of Hippo signaling, and a mutant form of YAP (YAP‐5SA), which can escape from LATS1/2‐mediated phosphorylation, rescued the Fat1‐mediated inhibition on the tumor‐initiating ability of NSCLC cells. This work prompts that Fat1 suppresses the tumor‐initiating ability of NSCLC cells by activating Hippo signaling. [ABSTRACT FROM AUTHOR]

Zinc finger protein 367 (ZNF367) has been documented as a new cancer‐related protein that exerts a pivotal role in the carcinogenesis of multiple cancers. However, whether ZNF367 plays a role in colorectal cancer has not been fully understood. Our data showed that ZNF367 expression was higher in colorectal cancer. Depletion of ZNF367 weakened the proliferative and invasive capabilities of colorectal cancer cells. Up‐regulation of ZNF367 enhanced the in vitro malignant features of colorectal cancer cells. Knockdown of ZNF367 impeded the activation of Yes‐associated protein (YAP1). Reactivation of YAP1 reversed the ZNF367‐knockdown‐mediated anticancer effects. Suppression of YAP1 significantly abolished ZNF367‐overexpression‐induced tumor‐promotion effects. Depletion of ZNF367 repressed the tumorigenicity of colorectal cancer cells in vivo. These findings demonstrate that ZNF367 is overexpressed in colorectal cancer and acts as a potential tumor‐promoter that contributes to the proliferation and invasion of colorectal cancer by enhancing the activation of YAP1 signaling. [ABSTRACT FROM AUTHOR]