Regulation of Hippo-YAP signaling axis by Isoalantolactone suppresses tumor progression in cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a devastating malignancy characterized by aggressive tumor growth and limited treatment options. Dysregulation of the Hippo signaling pathway and its downstream effector, Yes-associated protein (YAP), has been implicated in CCA development and progression. In this study, we investigated the effects of Isoalantolactone (IALT) on CCA cells to elucidate its effect on YAP activity and its potential clinical significance. Our findings demonstrate that IALT exerts cytotoxic effects, induces apoptosis, and modulates YAP signaling in SNU478 cells. We further confirmed the involvement of the canonical Hippo pathway by generating LATS1/LATS2 knockout cells, highlighting the dependence of IALT-mediated apoptosis and YAP phosphorylation on the Hippo-LATS signaling axis. In addition, IALT suppressed cell growth and migration, partially dependent on YAP-TEAD activity. These results provide insights into the therapeutic potential of targeting YAP in CCA and provide a rationale for developing of YAP-targeted therapies for this challenging malignancy.

Pasteurella multocida activates Rassf1-Hippo-Yap pathway to induce pulmonary epithelial apoptosis.

Pasteurella multocida is an opportunistic zoonotic pathogen that primarily causes fatal respiratory diseases, such as pneumonia and respiratory syndromes. However, the precise mechanistic understanding of how P. multocida disrupts the epithelial barrier in mammalian lung remains largely unknown. In this study, using unbiased RNA-seq analysis, we found that the evolutionarily conserved Hippo-Yap pathway was dysregulated after P. multocida infection. Given the complexity of P. multocida infection associated with lung injury and systemic inflammatory processes, we employed a combination of cell culture models, mouse models, and rabbit models to investigate the dynamics of the Hippo-Yap pathway during P. multocida infection. Our findings reveal that P. multocida infection activates the Hippo-Yap pathway both in vitro and in vivo, by upregulating the upstream factors p-Mst1/2, p-Lats1, and p-Yap, and downregulating the downstream effectors Birc5, Cyr61, and Slug. Conversely, pharmacological inhibition of the Hippo pathway by XMU-MP-1 significantly rescued pulmonary epithelial cell apoptosis in vitro and reduced lung injury, systemic inflammation, and mouse mortality in vivo. Mechanistic studies revealed that P. multocida induced up-regulation of Rassf1 expression, and Rassf1 enhanced Hippo-Yap pathway through phosphorylation. Accordingly, in vitro knockdown of Rassf1 significantly enhanced Yap activity and expression of Yap downstream factors and reduced apoptosis during P. multocida infection. P. multocida-infected rabbit samples also showed overexpression of Rassf1, p-Lats1, and p-Yap, suggesting that P. multocida activates the Rassf1-Hippo-Yap pathway. These results elucidate the pathogenic role of the Rassf1-Hippo-Yap pathway in P. multocida infection and suggest that this pathway has the potential to be a drug target for the treatment of pasteurellosis.

Inhibition of proprotein convertases activity results in repressed stemness and invasiveness of cancer stem cells in gastric cancer.

BACKGROUND: Gastric cancer (GC), the fourth leading cause of cancer-related death worldwide, with most deaths caused by advanced and metastatic disease, has limited curative options. Here, we revealed the importance of proprotein convertases (PCs) in the malignant and metastatic potential of GC cells through the regulation of the YAP/TAZ/TEAD pathway and epithelial-to-mesenchymal transition (EMT) in cancer stem cells (CSC). METHODS: The general PCs inhibitor, decanoyl-RVKR-chloromethyl-ketone (CMK), was used to repress PCs activity in CSCs of various GC cell lines. Their tumorigenic properties, drug resistance, YAP/TAZ/TEAD pathway activity, and invasive properties were then investigated in vitro, and their metastatic properties were explored in a mouse xenograft model. The prognostic value of PCs in GC patients was also explored in molecular databases of GC. RESULTS: Inhibition of PCs activity in CSCs in all GC cell lines reduced tumorsphere formation and growth, drug efflux, EMT phenotype, and invasive properties that are associated with repressed YAP/TAZ/TEAD pathway activity in vitro. In vivo, PCs' inhibition in GC cells reduced their metastatic spread. Molecular analysis of tumors from GC patients has highlighted the prognostic value of PCs. CONCLUSIONS: PCs are overexpressed in GC and associated with poor prognosis. PCs are involved in the malignant and metastatic potential of CSCs via the regulation of EMT, the YAP/TAZ/TEAD oncogenic pathway, and their stemness and invasive properties. Their repression represents a new strategy to target CSCs and impair metastatic spreading in GC.

Unleashing the Power of Yes-Associated Protein in Ferroptosis and Drug Resistance in Breast Cancer, with a Special Focus on Therapeutic Strategies.

The YAP protein is a critical oncogenic mediator within the Hippo signaling pathway and has been implicated in various cancer types. In breast cancer, it frequently becomes activated, thereby contributing to developing drug-resistance mechanisms. Recent studies have underscored the intricate interplay between YAP and ferroptosis within the breast tumor microenvironment. YAP exerts a negative regulatory effect on ferroptosis, promoting cancer cell survival and drug resistance. This review offers a concise summary of the current understanding surrounding the interplay between the YAP pathway, ferroptosis, and drug-resistance mechanisms in both bulk tumor cells and cancer stem cells. We also explore the potential of natural compounds alone or in combination with anticancer therapies for targeting the YAP pathway in treating drug-resistant breast cancer. This approach holds the promise of enhancing the effectiveness of current treatments and paving the way for developing novel therapeutics.

Hippo/YAP signaling pathway: a new therapeutic target for diabetes mellitus and vascular complications.

Diabetic angiopathy, which includes diabetic kidney disease (DKD), cardio-cerebrovascular disease, and diabetic retinopathy (DR) among other diseases, is one of the most common complications affecting diabetic patients. Among these, DKD, which is a major cause of morbidity and mortality, affects about 40% of diabetic patients. Similarly, DR involves retinal neovascularization and neurodegeneration as a result of chronic hyperglycemia and is the main cause of visual impairment and blindness. In addition, inflammation also promotes atherosclerosis and diabetes, with atherosclerosis-related cardiovascular diseases being often a main cause of disability or death in diabetic patients. Given that vascular diseases caused by diabetes negatively impact human health, it is therefore important to identify appropriate treatments. In this context, some studies have found that the Hippo/Yes-associated protein (YAP) pathway is a highly evolutionarily conserved protein kinase signal pathway that regulates organ growth and size through its effector signaling pathway Transcriptional co-Activator with PDZ-binding motif (TAZ) and its YAP. YAP is a key factor in the Hippo pathway. The activation of YAP regulates gluconeogenesis, thereby regulating glucose tolerance levels; silencing the YAP gene thereby prevents the formation of glomerular fibrosis. YAP can combine with TEA domain family members to regulate the proliferation and migration of retinal vascular endothelial cells (ECs), so YAP plays a prominent role in the formation and pathology of retinal vessels. In addition, YAP/TAZ activation and translocation to the nucleus promote endothelial inflammation and monocyte-EC attachment, which can increase diabetes-induced cardiovascular atherosclerosis. Hippo/YAP signaling pathway provides a potential therapeutic target for diabetic angiopathy, which can prevent the progression of diabetes to DR and improve renal fibrosis and cardio-vascular atherosclerosis.

Identification of topoisomerase 2A as a novel bone metastasis-related gene in liver hepatocellular carcinoma.

BACKGROUND: Bone is the second most frequent site of metastasis for Liver hepatocellular carcinoma (LIHC), which leads to an extremely poor prognosis. Identifying novel biomarkers and therapeutic targets for LIHC patients with bone metastasis is urgently needed. METHODS: In this study, we used multiple databases for comprehensive bioinformatics analysis, including TCGA, GEO, ICGC, GTEx, TISIDB, and TIMER, to identify key genes related to bone metastasis of LIHC. Clinical tissues and tissue microarray were adopted to assess the expression of TOP2A through qRT-PCR and immunohistochemistry analyses in LIHC. Gene enrichment analysis, DNA methylation, gene mutation, prognosis, and tumor immunity associated with TOP2A in LIHC were investigated. In vitro and in vivo experiments were performed to explore the functional role of TOP2A in LIHC bone metastasis. RESULTS: We identified that TOP2A was involved in LIHC bone metastasis. Clinically, TOP2A was highly expressed in LIHC tumoral specimens, with the highest level in the bone metastasis lesions. TOP2A was an independent prognostic factor that higher expression of TOP2A was markedly associated with poorer prognosis in LIHC. Moreover, the abnormal expression of TOP2A might be related to DNA hypomethylation, often accompanied by TP53 mutation, immune escape and immunotherapy failure. Enrichment analysis and validation experiments unveiled that TOP2A stimulated the Hippo-YAP signaling pathway in LIHC. Functional assays confirmed that TOP2A could promote bone-specific metastatic potential and tumor-induced osteolysis in LIHC. CONCLUSIONS: These findings unveil that TOP2A might be a novel prognostic biomarker and therapeutic target for LIHC bone metastasis.

Modulation of the hippo-YAP pathway by cyclic stretch in rat type 2 alveolar epithelial cells-a proof-of-concept study.

Background: Mechanical ventilation (MV) is a life supporting therapy but may also cause lung damage. This phenomenon is known as ventilator-induced lung injury (VILI). A potential pathomechanisms of ventilator-induced lung injury may be the stretch-induced production and release of cytokines and pro-inflammatory molecules from the alveolar epithelium. Yes-associated protein (YAP) might be regulated by mechanical forces and involved in the inflammation cascade. However, its role in stretch-induced damage of alveolar cells remains poorly understood. In this study, we explored the role of YAP in the response of alveolar epithelial type II cells (AEC II) to elevated cyclic stretch in vitro. We hypothesize that Yes-associated protein activates its downstream targets and regulates the interleukin-6 (IL-6) expression in response to 30% cyclic stretch in AEC II. Methods: The rat lung L2 cell line was exposed to 30% cyclic equibiaxial stretch for 1 or 4 h. Non-stretched conditions served as controls. The cytoskeleton remodeling and cell junction integrity were evaluated by F-actin and Pan-cadherin immunofluorescence, respectively. The gene expression and protein levels of IL-6, Yes-associated protein, Cysteine-rich angiogenic inducer 61 (Cyr61/CCN1), and connective tissue growth factor (CTGF/CCN2) were studied by real-time polymerase chain reaction (RT-qPCR) and Western blot, respectively. Verteporfin (VP) was used to inhibit Yes-associated protein activation. The effects of 30% cyclic stretch were assessed by two-way ANOVA. Statistical significance as accepted at p < 0.05. Results: Cyclic stretch of 30% induced YAP nuclear accumulation, activated the transcription of Yes-associated protein downstream targets Cyr61/CCN1 and CTGF/CCN2 and elevated IL-6 expression in AEC II after 1 hour, compared to static control. VP (2 µM) inhibited Yes-associated protein activation in response to 30% cyclic stretch and reduced IL-6 protein levels. Conclusion: In rat lung L2 AEC II, 30% cyclic stretch activated YAP, and its downstream targets Cyr61/CCN1 and CTGF/CCN2 and proinflammatory IL-6 expression. Target activation was blocked by a Yes-associated protein inhibitor. This novel YAP-dependent pathway could be involved in stretch-induced damage of alveolar cells.

PIP5Kγ Mediates PI(4,5)P2/Merlin/LATS1 Signaling Activation and Interplays with Hsc70 in Hippo-YAP Pathway Regulation.

The type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family produces the critical lipid regulator phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in the plasma membrane (PM). Here, we investigated the potential role of PIP5Kγ, a PIP5K isoform, in the Hippo pathway. The ectopic expression of PIP5Kγ87 or PIP5Kγ90, two major PIP5Kγ splice variants, activated large tumor suppressor kinase 1 (LATS1) and inhibited Yes-associated protein (YAP), whereas PIP5Kγ knockdown yielded opposite effects. The regulatory effects of PIP5Kγ were dependent on its catalytic activity and the presence of Merlin and LATS1. PIP5Kγ knockdown weakened the restoration of YAP phosphorylation upon stimulation with epidermal growth factor or lysophosphatidic acid. We further found that PIP5Kγ90 bound to the Merlin's band 4.1/ezrin/radixin/moesin (FERM) domain, forming a complex with PI(4,5)P2 and LATS1 at the PM. Notably, PIP5Kγ90, but not its kinase-deficient mutant, potentiated Merlin-LATS1 interaction and recruited LATS1 to the PM. Consistently, PIP5Kγ knockdown or inhibitor (UNC3230) enhanced colony formation in carcinoma cell lines YAP-dependently. In addition, PIP5Kγ90 interacted with heat shock cognate 71-kDa protein (Hsc70), which also contributed to Hippo pathway activation. Collectively, our results suggest that PIP5Kγ regulates the Hippo-YAP pathway by forming a functional complex with Merlin and LATS1 at the PI(4,5)P2-rich PM and via interplay with Hsc70.

Iron overload triggering ECM-mediated Hippo/YAP pathway in follicle development: a hypothetical model endowed with therapeutic implications.

Disruption of iron homeostasis plays a negative role in follicle development. The dynamic changes in follicle growth are dependent on Hippo/YAP signaling and mechanical forces. However, little is known about the liaison between iron overload and the Hippo/YAP signalling pathway in term of folliculogenesis. Here, based on the available evidence, we established a hypothesized model linking excessive iron, extracellular matrix (ECM), transforming growth factor-ß (TGF-ß) and Hippo/Yes-associated protein (YAP) signal regarding follicle development. Hypothetically, the TGF-ß signal and iron overload may play a synergistic role in ECM production via YAP. We speculate that the dynamic homeostasis of follicular iron interacts with YAP, increasing the risk of ovarian reserve loss and may enhance the sensitivity of follicles to accumulated iron. Hence, therapeutic interventions targeting iron metabolism disorders, and Hippo/YAP signal may alter the consequences of the impaired developmental process based on our hypothesis, which provides potential targets and inspiration for further drug discovery and development applied to clinical treatment.

HIF­1α inhibits ferroptosis and promotes malignant progression in non­small cell lung cancer by activating the Hippo­YAP signalling pathway.

Ferroptosis and hypoxia-inducible factor 1α (HIF-1α) have critical roles in human tumors. The aim of the present study was to investigate the associations between ferroptosis, HIF-1α and cell growth in non-small cell lung cancer (NSCLC) cells. The lung cancer cell lines SW900 and A549 were evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to detect the expression of HIF-1α. Cell Counting Kit-8, flow cytometry and Transwell migration assays were used to measure cell viability, apoptosis and invasion, respectively. The production of reactive oxygen species (ROS) and levels of malondialdehyde (MDA), glutathione (GSH) and ferrous ion (Fe2+) were determined using detection kits. The expression levels of glutathione peroxidase 4 (GPX4) and Yes-associated protein 1 (YAP1) were detected using RT-qPCR and western blotting. The results showed that the expression of HIF-1α was significantly upregulated in NSCLC cells compared with normal human bronchial epithelial cells. Small interfering RNA specific to HIF-1α (si-HIF-1α) significantly decreased the proliferation and invasion of NSCLC cells and increased their apoptosis. si-HIF-1α also increased the levels of ROS, MDA and Fe2+ but decreased GSH and GPX4 levels in A549 cells. Additionally, si-HIF-1α increased phosphorylated (p-)YAP1 levels, suppressed GPX4 and YAP1 expression, and attenuated the YAP1 overexpression-induced changes in YAP1, p-YAP1 and GPX4 levels and cell viability. The ferroptosis antagonist ferrostatin-1 partially attenuated the effects of si-HIF-1α on the NSCLC cells, while the ferroptosis agonist erastin further inhibited NSCLC growth by blocking HIF-1α expression. In conclusion, the silencing of HIF-1α induces ferroptosis by suppressing Hippo-YAP pathway activation in NSCLC cells. The present study provides novel insights into the malignant progression of NSCLC and suggests that HIF-1α is an effective target for the treatment of NSCLC.

MiR-34a-5p promotes autophagy and apoptosis of ovarian granulosa cells via the Hippo-YAP signaling pathway by targeting LEF1 in chicken.

Follicular atresia is a natural physiological phenomenon in poultry reproduction. It is well known that follicular atresia is caused by both autophagy and apoptosis of granulosa cells. In current experiment, we evaluated the function of miR-34a-5p on autophagy and apoptosis in chicken follicular atresia. First, the follicular atresia model of chicken was successfully constructed by subcutaneous injection of tamoxifen (TMX), and found the expression of miR-34a-5p in the atresia follicles obviously increased. Then, we confirmed that miR-34a-5p accelerates autophagy and apoptosis of chicken granulose cells in vitro, and miR-34a-5p could induce apoptosis by mediating autophagy. Mechanistically, lymphoid enhancer binding factor 1 (LEF1) was deemed as a target gene for miR-34a-5p. On the contrary, LEF1 overexpression attenuated the autophagy and apoptosis of chicken granular cells. In addition, it was confirmed that the miR-34a-5p/LEF1 axis plays a regulatory role in chicken granulosa cells by mediating the Hippo-YAP signaling pathway. Taken together, this study demonstrated that miR-34a-5p contributes to autophagy and apoptosis of chicken follicular granulosa cells by targeting LEF1 to mediate the Hippo-YAP signaling pathway.

Hippo-YAP pathway is involved in the effect of NaAsO / 中国药理学通报

Aim To explore the effects of NaAsO

Molecular Mechanism of Curcumin Derivative on YAP Pathway against Ovarian Cancer.

The purpose of this study is to study the effect of curcumin derivative WZ10 on the proliferation, invasion and apoptosis of ovarian cancer OVCAR3 cells, and to explore its mechanism. MTT assay was used to detect the effect of WZ10 on the proliferation of ovarian cancer OVCAR3 cells; Annexin V/PI double staining flow cytometry was used to detect the effect of WZ10 on cell apoptosis; Transwell method was used to detect the effect of WZ10 on cell invasiveness; Western blot was used to investigate the effect of WZ10 Mechanisms affecting OVCAR3 activity in ovarian cancer in vitro. Our results show that WZ10 treatment could significantly inhibit the proliferation and invasion of OVCAR3 cells, induce apoptosis of OVCAR3 cells in a dose-dependent manner. After knockdown of Hippo expression with sh-RNA, further combined treatment with WZ10 had no significant image on ovarian cancer OVCAR3 cells. In conclusion: WZ10 can significantly inhibit the proliferation of OVCAR3 cells, reduce cell invasion and proliferation by downregulating the activation of Hippo-YAP pathway, and induce cell apoptosis.

Hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit beta gene as a tumour suppressor in stomach adenocarcinoma.

Background: Stomach adenocarcinoma (STAD) is the most common type of gastric cancer. In this study, the functions and potential mechanisms of hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit beta (HADHB) in STAD were explored. Methods: Different bioinformatics analyses were performed to confirm HADHB expression in STAD. HADHB expression in STAD tissues and cells was also evaluated using western blot, qRT-PCR, and immunohistochemistry. Further, the viability, proliferation, colony formation, cell cycle determination, migration, and wound healing capacity were assessed, and the effects of HADHB on tumour growth, cell apoptosis, and proliferation in nude mice were determined. The upstream effector of HADHB was examined using bioinformatics analysis and dual luciferase reporter assay. GSEA was also employed for pathway enrichment analysis and the expression of Hippo-YAP pathway-related proteins was detected. Results: The expression of HADHB was found to be low in STAD tissues and cells. The upregulation of HADHB distinctly repressed the viability, proliferation, colony formation, cell cycle progression, migration, invasion, and wound healing of HGC27 cells, while knockdown of HADHB led to opposite effects. HADHB upregulation impeded tumour growth and cell proliferation, and enhanced apoptosis in nude mice. KLF4, whose expression was low in STAD, was identified as an upstream regulator of HADHB. KLF4 upregulation abolished the HADHB knockdown-induced tumour promoting effects in AGS cells. Further, HADHB regulates the Hippo-YAP pathway, which was validated using a pathway rescue assay. Low expression of KLF4 led to HADHB downregulation in STAD. Conclusion: HADHB might function as a tumour suppressor gene in STAD by regulation the Hippo-YAP pathway.

The Hippo-YAP pathway in various cardiovascular diseases: Focusing on the inflammatory response.

The Hippo pathway was initially discovered in Drosophila melanogaster and mammals as a key regulator of tissue growth both in physiological and pathological states. Numerous studies depict the vital role of the Hippo pathway in cardiovascular development, heart regeneration, organ size and vascular remodeling through the regulation of YAP (yes-associated protein) translocation. Recently, an increasing number of studies have focused on the Hippo-YAP pathway in inflammation and immunology. Although the Hippo-YAP pathway has been revealed to play controversial roles in different contexts and cell types in the cardiovascular system, the mechanisms regulating tissue inflammation and the immune response remain to be clarified. In this review, we summarize findings from the past decade on the function and mechanism of the Hippo-YAP pathway in CVDs (cardiovascular diseases) such as myocardial infarction, cardiomyopathy and atherosclerosis. In particular, we emphasize the role of the Hippo-YAP pathway in regulating inflammatory cell infiltration and inflammatory cytokine activation.

CD146 interaction with integrin ß1 activates LATS1-YAP signaling and induces radiation-resistance in breast cancer cells.

Radiotherapy is an indispensable modality in comprehensive treatment of breast cancer. However, inherent or acquired radiation resistance of tumors compromises the efficacy of radiotherapy. Herein, we found that CD146, a unique epithelial-to-mesenchymal transition (EMT) inducer particularly highly expressed in triple-negative breast cancer (TNBC), is dramatically induced by ionizing irradiation. Further study demonstrates that CD146 promotes tumor cell radioresistance in vitro and in vivo. Specifically, we report the underlying mechanism that CD146 activates YAP protein, and drives its relocation from plasma to nucleus by regulating LATS1, and promoting abnormal DNA damage repair, as well as inducing EMT and stemness. Moreover, CD146 can form a novel co-receptor complex with integrin ß1 and induces radiation-resistance in breast cancer. Dual inhibition of CD146 and integrin ß1 activity had a stronger inhibitory effect on breast cancer tumor growth and synergistically increased their sensitivity to radiotherapy. This study identifies a unique function of CD146 implicates with integrin ß1 and YAP signaling, contributing to radiation resistance. Targeted therapy against CD146 or inhibition of integrin ß1 is a potential strategy to overcome radiotherapeutic resistance of breast cancer.

Treatment of ulcerative colitis with Wu-Mei-Wan by inhibiting intestinal inflammatory response and repairing damaged intestinal mucosa.

BACKGROUND: Wu-Mei-Wan (WMW), a traditional Chinese medicine, has been applied in the treatment of gastrointestinal diseases with long-term diarrhea and mucopurulent bloody stool as the main symptoms since ancient times. Studies have shown that WMW inhibits intestinal inflammation, repairs damaged intestinal mucosa, resists colon necrosis, and resists intestinal fibrosis. However, the specific mechanism of action is not yet clear. OBJECTIVE: Ulcerative colitis (UC), an intestinal disease with intestinal inflammation and injury as the main pathological manifestations, is one of the high-risk factors for colon cancer. Inhibiting the inflammatory response and promoting colonic epithelial repair are critical to the treatment of UC. However, there is still a lack of remedies with satisfactory curative effects. In this study, the role of WMW in dextran sulfate sodium (DSS)-induced colitis in mice and its related mechanisms are discussed from two aspects: intestinal inflammation and tissue repair. METHODS: DSS was used to induce colitis in mice and the therapeutic effect of WMW was analyzed by disease activity score, histopathological score, colon length measurement, serum cytokine detection, and flow cytometry. Macrophage activation and colonic stem cell proliferation were observed by immunohistochemistry. The expression of critical molecules in macrophage activation and colonic stem cell proliferation signaling pathways in colon tissue was detected with immunohistochemistry, immunofluorescence staining, RT-qPCR, and Western blot. RESULTS: WMW could significantly alleviate DSS-induced colitis. We showed that WMW could reduce disease activity, reduce pathological scores, limit weight loss, inhibit colon shortening, inhibit inflammatory factor secretion, attenuate inflammatory response, and promote the repair of damaged colonic epithelium. WMW inhibited the activation of colonic macrophages, and its mechanism might be inhibiting the Notch/NF-κB/NLRP3 pathway; WMW promoted the proliferation of colonic stem cells, and its mechanism was associated with the regulation of the Hippo/YAP signaling pathway. CONCLUSION: The results of this study suggested that WMW could treat UC via a mechanism that inhibited the intestinal inflammatory response and repaired damaged intestinal mucosa.

Hippo-YAP signaling activation and cross-talk with PI3K in oral cancer: A retrospective cohort study.

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.

A non-transcriptional function of Yap regulates the DNA replication program in Xenopus laevis.

In multicellular eukaryotic organisms, the initiation of DNA replication occurs asynchronously throughout S-phase according to a regulated replication timing program. Here, using Xenopus egg extracts, we showed that Yap (Yes-associated protein 1), a downstream effector of the Hippo signalling pathway, is required for the control of DNA replication dynamics. We found that Yap is recruited to chromatin at the start of DNA replication and identified Rif1, a major regulator of the DNA replication timing program, as a novel Yap binding protein. Furthermore, we show that either Yap or Rif1 depletion accelerates DNA replication dynamics by increasing the number of activated replication origins. In Xenopus embryos, using a Trim-Away approach during cleavage stages devoid of transcription, we found that either Yap or Rif1 depletion triggers an acceleration of cell divisions, suggesting a shorter S-phase by alterations of the replication program. Finally, our data show that Rif1 knockdown leads to defects in the partitioning of early versus late replication foci in retinal stem cells, as we previously showed for Yap. Altogether, our findings unveil a non-transcriptional role for Yap in regulating replication dynamics. We propose that Yap and Rif1 function as brakes to control the DNA replication program in early embryos and post-embryonic stem cells.

[Metformin inhibits proliferation and promotes apoptosis of HER-2 positive breast cancer cells possibly through the Hippo-YAP pathway].

OBJECTIVE: To investigate the effect of metformin on the proliferation and apoptosis of HER-2-positive breast cancer cell line SKBR3 and explore the possible mechanism of its action. METHODS: SKBR3 cells were treated with different concentrations (20-120 µmol/L) of metformin, and the changes in cell proliferation and colony formation ability were assessed using CCK-8 assay and crystal violet staining, respectively. Flow cytometry was performed to analyze cell apoptosis and cell cycle changes. Real-time fluorescent quantitative PCR (qRT-PCR) was used to detect mRNA expressions of YAP, TAZ, EGFR, CTGF, CYR61, E-cadherin, N-cadherin, vimentin and fibronectin in the treated cells, and the protein expressions of YAP and TAZ were detected using Western blotting; immunofluorescence assay was used to observe YAP/TAZ nuclear translocation in the cells. RESULTS: Metformin treatment significantly inhibited the proliferation of SKBR3 cells (P < 0.05) in a concentration- and time-dependent manner. The results of flow cytometry showed that metformin significantly promoted apoptosis and caused cell cycle arrest at G1 phase in SKBR3 cells. Metformin treatment significantly down-regulated the mRNA expressions of YAP, TAZ, EGFR, CTGF and CYR61, N-cadherin, vimentin and fibronectin (P < 0.05) and up-regulated the expression of E-cadherin (P < 0.05); Western blotting results showed that YAP and TAZ protein expressions were significantly down-regulated in the cells after metformin treatment (P < 0.05). Immunofluorescence assay revealed that metformin treatment caused the concentration of YAP and TAZ in the cytoplasm, and significantly reduced their amount in the cell nucleus. CONCLUSION: Metformin can inhibit proliferation and promote apoptosis and epithelal-mesenchymal transition of HER-2 positive breast cancer cells possibly by that inhibing YAP and TAZ expression and their nuclear localization.