The Hippo Pathway: Immunity and Cancer

CDK5 interacts with MST2 and modulates the Hippo signalling pathway

MST2 (STK3) is a major upstream kinase in the Hippo signalling pathway, an evolutionary conserved pathway in regulation of organ size, self-renewal and tissue homeostasis. Its downstream effectors are the transcriptional regulators YAP and TAZ. This pathway is regulated by a variety of factors, such as substrate stiffness or cell-cell contacts. Using a yeast two-hybrid screen, we detected a novel interaction between the kinases MST2 and CDK5, which we further confirmed by co-immunoprecipitation experiments. Cyclin-dependent kinase 5 (CDK5) is an unusual member of the family of cyclin-dependent kinases, involved in tumour growth and angiogenesis. Although a link between CDK5 and Hippo has been previously postulated, the mode of action is still elusive. Here, we show that knockdown of CDK5 causes reduced transcriptional activity of YAP and that CDK5 influences the phosphorylation levels of the Hippo upstream kinase LATS1. Moreover, a phosphoproteomics approach revealed that CDK5 interferes with the phosphorylation of DLG5, another upstream kinase, which regulates the Hippo pathway. Hence, CDK5 seems to act as a signalling hub for integrating the Hippo pathway and other signalling cascades. These interactions might have important implications for the use of CDK5 inhibitors, which are already in clinical use for tumour diseases.

Anti-cancer effects of nitazoxanide in epithelial ovarian cancer in-vitro and in-vivo

Epithelial ovarian cancer is one of the most lethal gynecologic malignancies and poses a considerable threat to women's health. Although the progression-free survival of patients has been prolonged with the application of anti-angiogenesis drugs and Poly (ADP-ribose) polymerases (PARP) inhibitors, overall survival has not substantially improved. Thus, new therapeutic strategies are essential for the treatment of ovarian cancer. Nitazoxanide (NTZ), an FDA-approved anti-parasitic drug, has garnered attention for its potential anti-cancer activity. However, the anti-tumor effects and possible underlying mechanisms of NTZ on ovarian cancer remain unclear. In this study, we investigated the anti-tumor effects and the mechanism of NTZ on ovarian cancer in vitro and in vivo. We found that NTZ inhibited the proliferation of A2780 and SKOV3 epithelial ovarian cancer cells in a time- and concentration-dependent manner; Furthermore, NTZ suppressed the metastasis and invasion of A2780 and SKOV3 cells in vitro, correlating with the inhibition of epithelial-mesenchymal transition; Additionally, NTZ suppressed the Hippo/YAP/TAZ signaling pathway both in vitro and in vivo and demonstrated a good binding activity with core genes of Hippo pathway, including Hippo, YAP, TAZ, LATS1, and LATS2. Oral administration of NTZ inhibited tumor growth in xenograft ovarian cancer mice models without causing considerable damage to major organs. Overall, these data suggest that NTZ has therapeutic potential for treating epithelial ovarian cancer.

Prognostic role of TEAD4 in TNBC: in-silico inhibition of the TEAD4-YAP interaction by flufenamic acid analogs

Triple-negative breast cancer (TNBC) poses a significant global health challenge due to its highly aggressive nature and invasive characteristics. Dysregulation of the Hippo pathway, a key regulator of various biological processes, is observed in TNBC, and its inhibition holds promise for impeding cancer growth. This in-silico analysis investigates the role of Transcriptional Enhanced Associate Domain 4 (TEAD4) in TNBC and its interaction with Yes Associated Protein (YAP) in cancer progression. Our results demonstrate that TEAD4 upregulation is linked to poor prognosis in TNBC, emphasizing its critical role in the disease. Moreover, we identify CID44521006, an analog of Flufenamic acid, as a potential therapeutic compound capable of disrupting the TEAD4-YAP interaction by binding to the YAP-binding domain of TEAD4. These findings underscore the significance of TEAD4 in TNBC and propose CID44521006 as a promising candidate for therapeutic intervention. The study contributes valuable insights to advance treatment options for TNBC, offering a potential avenue for the development of targeted therapies against this aggressive form of breast cancer.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00239-8.

Targeting the Hippo Pathway in Cutaneous Melanoma

Melanoma is the most aggressive form of skin cancer. In the advanced stage of development, it is resistant to currently available therapeutic modalities. Increased invasiveness and metastatic potential depend on several proteins involved in various signal transduction pathways. Hippo signaling plays a vital role in malignant transformation. Dysfunctions of the Hippo pathway initiate the expression of tumor growth factors and are associated with tumor growth and metastasis formation. This review summarizes the recent achievements in studying the role of the Hippo pathway in melanoma pathogenesis and points to the potential specific targets for anti-melanoma therapy.

The RNF214-TEAD-YAP signaling axis promotes hepatocellular carcinoma progression via TEAD ubiquitylation

RNF214 is an understudied ubiquitin ligase with little knowledge of its biological functions or protein substrates. Here we show that the TEAD transcription factors in the Hippo pathway are substrates of RNF214. RNF214 induces non-proteolytic ubiquitylation at a conserved lysine residue of TEADs, enhances interactions between TEADs and YAP, and promotes transactivation of the downstream genes of the Hippo signaling. Moreover, YAP and TAZ could bind polyubiquitin chains, implying the underlying mechanisms by which RNF214 regulates the Hippo pathway. Furthermore, RNF214 is overexpressed in hepatocellular carcinoma (HCC) and inversely correlates with differentiation status and patient survival. Consistently, RNF214 promotes tumor cell proliferation, migration, and invasion, and HCC tumorigenesis in mice. Collectively, our data reveal RNF214 as a critical component in the Hippo pathway by forming a signaling axis of RNF214-TEAD-YAP and suggest that RNF214 is an oncogene of HCC and could be a potential drug target of HCC therapy.

Amplification of Hippo Signaling Pathway Genes Is Governed and Implicated in the Serous Subtype-Specific Ovarian Carcino-Genesis

Among women, ovarian cancer ranks as the fifth most common cause of cancer-related deaths. This study examined the impact of Hippo signaling pathway on ovarian carcinogenesis. Therefore, the signatures related to Hippo signaling pathway were derived from the molecular signatures database (MSigDB) and were used for further analysis. The Z score-based pathway activation scoring method was employed to investigate the expression patterns of these signatures in the mRNA expression profiles of ovarian cancer cohorts. Compared to other subtype tumors, the results of this study show that the Hippo signaling pathway signatures are dysregulated prominently in serous subtype-specific ovarian carcinogenesis. A receiver operating characteristic (ROC) curve-based results of the Hippo gene set, yes-associated protein 1 (YAP1), and mammalian sterile 20-like kinases 1 (MST1) genes can predict the serous subtype tumors by higher specificity and sensitivity with significant areas under the curve values also further reconfirmed these signaling dysregulations. Moreover, these gene sets were studied further for mutation analysis in the profile of high-grade serous ovarian adenocarcinoma in the cBioPortal database. The OncoPrint results reveal that these Hippo signaling pathway genes are amplified highly during the grade three and stage third or fourth of serous type ovarian tumors. In addition, the results of the Dependency Map (DepMap) plot also clearly show that these genes are amplified significantly across the ovarian cancer cell lines. Finally, overall survival (OS) curve plot investigations also revealed that these gene expressions show poor survival patterns linked to highly expressed conditions in serous subtypes of ovarian cancer patients with significant p-values (p < 0.05). Thus, the current finding would help to develop the targeted therapies treatment for serous subtype ovarian carcinogenesis.

Hippo pathway in non-small cell lung cancer: mechanisms, potential targets, and biomarkers

Lung cancer is the primary contributor to cancer-related deaths globally, and non-small cell lung cancer (NSCLC) constitutes around 85% of all lung cancer cases. Recently, the emergence of targeted therapy and immunotherapy revolutionized the treatment of NSCLC and greatly improved patients' survival. However, drug resistance is inevitable, and extensive research has demonstrated that the Hippo pathway plays a crucial role in the development of drug resistance in NSCLC. The Hippo pathway is a highly conserved signaling pathway that is essential for various biological processes, including organ development, maintenance of epithelial balance, tissue regeneration, wound healing, and immune regulation. This pathway exerts its effects through two key transcription factors, namely Yes-associated protein (YAP) and transcriptional co-activator PDZ-binding motif (TAZ). They regulate gene expression by interacting with the transcriptional-enhanced associate domain (TEAD) family. In recent years, this pathway has been extensively studied in NSCLC. The review summarizes a comprehensive overview of the involvement of this pathway in NSCLC, and discusses the mechanisms of drug resistance, potential targets, and biomarkers associated with this pathway in NSCLC.

Identification of PTPN12 Phosphatase as a Novel Negative Regulator of Hippo Pathway Effectors YAP/TAZ in Breast Cancer

The Hippo pathway plays crucial roles in governing various biological processes during tumorigenesis and metastasis. Within this pathway, upstream signaling stimuli activate a core kinase cascade, involving MST1/2 and LATS1/2, that subsequently phosphorylates and inhibits the transcriptional co-activators YAP and its paralog TAZ. This inhibition modulates the transcriptional regulation of downstream target genes, impacting cell proliferation, migration, and death. Despite the acknowledged significance of protein kinases in the Hippo pathway, the regulatory influence of protein phosphatases remains largely unexplored. In this study, we conducted the first gain-of-functional screen for protein tyrosine phosphatases (PTPs) regulating the Hippo pathway. Utilizing a LATS kinase biosensor (LATS-BS), a YAP/TAZ activity reporter (STBS-Luc), and a comprehensive PTP library, we identified numerous novel PTPs that play regulatory roles in the Hippo pathway. Subsequent experiments validated PTPN12, a master regulator of oncogenic receptor tyrosine kinases (RTKs), as a previously unrecognized negative regulator of the Hippo pathway effectors, oncogenic YAP/TAZ, influencing breast cancer cell proliferation and migration. In summary, our findings offer valuable insights into the roles of PTPs in the Hippo signaling pathway, significantly contributing to our understanding of breast cancer biology and potential therapeutic strategies.

Cathepsin C regulates tumor progression via the Yes-associated protein signaling pathway in non-small cell lung cancer

Cathepsin C (CTSC), also known as dipeptidyl peptidase I, is a cathepsin with lysosomal exocysteine protease activity and a central coordinator for the activation of neutrophil-derived serine proteases in the lysosomes of neutrophils. Although the role of CTSC in various cancers, including liver and breast cancers, has recently been reported, its role in non-small cell lung cancer (NSCLC) is largely unknown. This study aimed to investigate the functional role of CTSC in NSCLC and the molecular mechanisms underlying CTSC involvement in disease progression. CTSC overexpression markedly enhanced the growth, motility, and invasiveness of NSCLC cells in vitro and in vivo. CTSC knockdown using shRNA in NSCLC cells reversed the migratory and invasive behavior of NSCLC cells. CTSC also induced epithelial-mesenchymal transition through the Yes-associated protein signaling pathway. In addition, our analyses of clinical samples confirmed that high CTSC expression was associated with lymph node metastasis and recurrence in lung adenocarcinoma. In conclusion, CTSC plays an important role in the progression of NSCLC. Thus, targeting CTSC may be a promising treatment option for patients with NSCLC.

The induction of SHP-1 degradation by TAOK3 ensures the responsiveness of T cells to TCR stimulation

Thousand-and-one-amino acid kinase 3 (TAOK3) is a serine and threonine kinase that belongs to the STE-20 family of kinases. Its absence reduces T cell receptor (TCR) signaling and increases the interaction of the tyrosine phosphatase SHP-1, a major negative regulator of proximal TCR signaling, with the kinase LCK, a component of the core TCR signaling complex. Here, we used mouse models and human cell lines to investigate the mechanism by which TAOK3 limits the interaction of SHP-1 with LCK. The loss of TAOK3 decreased the survival of naïve CD4+ T cells by dampening the transmission of tonic and ligand-dependent TCR signaling. In mouse T cells, Taok3 promoted the secretion of interleukin-2 (IL-2) in response to TCR activation in a manner that depended on Taok3 gene dosage and on Taok3 kinase activity. TCR desensitization in Taok3-/- T cells was caused by an increased abundance of Shp-1, and pharmacological inhibition of Shp-1 rescued the activation potential of these T cells. TAOK3 phosphorylated threonine-394 in the phosphatase domain of SHP-1, which promoted its ubiquitylation and proteasomal degradation. The loss of TAOK3 had no effect on the abundance of SHP-2, which lacks a residue corresponding to SHP-1 threonine-394. Modulation of SHP-1 abundance by TAOK3 thus serves as a rheostat for TCR signaling and determines the activation threshold of T lymphocytes.

ADCY6 is a potential prognostic biomarker and suppresses OTSCC progression via Hippo signaling pathway

Oral tongue squamous cell carcinoma (OTSCC) is a malignant tumor. Recently, studies have found that adenylate cyclase 6 (ADCY6) plays a pivotal role in many lethal tumors formation processes. The role of ADCY6 in OTSCC remains unknown. The expression of ADCY6 in OTSCC tissue samples was detected. The clinical significance of ADCY6 in OTSCC was analyzed by statistical methods. OTSCC cell lines were selected to analyze the biological function of ADCY6. Meanwhile, the effect of ADCY6 on the growth of OTSCC in vivo was explored using subcutaneous tumorigenesis assay. WB assay was used to detect the underlying signaling pathway. Cell function recovery test used to investigate the mechanism of ADCY6-promoting OTSCC malignant biological behavior via Hippo signaling pathway. We report that ADCY6 was obviously downregulated in OTSCC tissue samples and cell lines. Importantly, lower expression of ADCY6 indicates a poorer prognosis in patients with OTSCC, and its expression is significantly correlated with TNM stage and tumor size. Functionally, forced expression of ADCY6 can significantly inhibit the proliferation, migration, invasion, and promote apoptosis of OTSCC cells. Mechanistically, we demonstrated that ADCY6 upregulation impaired Hippo signaling pathway to reduce the malignant biological behavior of OTSCC. Generally, our findings suggest that ADCY6 suppressed Hippo signaling pathway to regulate malignant biological behavior in OTSCC, which provide new cues for further exploring the mechanism of occurrence and development of OTSCC.

RGS16 regulates Hippo-YAP activity to promote esophageal cancer cell proliferation and migration

Esophageal Squamous Cell Carcinoma (ESCC) is a common malignant tumor of digestive tract, accounting for 90% of all pathological types of esophageal cancer. Despite the rapid development of multi-disciplinary treatment such as surgery, chemotherapy, radiotherapy and chemoradiotherapy, the prognosis of patients with ESCC is still poor. Regulators of G-protein signaling (RGSs) are involved in the processes of various cancers. The expression levels of its family member RGS16 are abnormally elevated in a variety of tumors, but its role in ESCC is still unclear. We found that RGS16 expression is aberrantly increased in ESCC tissues and correlated with poor prognosis of ESCC patients from The Cancer Genome Atlas (TCGA) database and our collected ESCC tissues. Moreover, knockdown of RGS16 in two ESCC cells could indeed inhibit their proliferation and migration. We further explored the molecular mechanism of RGS16 in ESCC, and the correlation analysis from TCGA database showed that the mRNA levels of RGS16 was positively correlated with that of CTGF and CYR61, two target genes of Hippo-YAP signaling. Consistently, RGS16- knockdown significantly inhibited the expression of CTGF and CYR61 in ESCC cells. We found that the phosphorylation levels of LATS1 and YAP were significantly increased and YAP translocated into the cytoplasm after depletion of RGS16 in ESCC cells. Also, RGS16-knockdown promoted the interaction between LATS1 and upstream kinase MST1. In addition, reintroduction of a constitutive active YAP5A mutant significantly rescued CTGF expression and cell proliferation in RGS16-knockdown cells. Together, our work revealed that RGS16 promoted YAP activity through disrupting the interaction between LATS1 and MST1, thus promoting the proliferation and migration of ESCC cells.

The Telluride YAP/TAZ and TEAD Workshop: A Small Meeting with a Big Impact

Funding the research needed to advance our understanding of rare cancers is very challenging [...].

Targeting the mechanism of IRF3 in sepsis-associated acute kidney injury via the Hippo pathway

Sepsis-induced inflammatory damage and adaptive repair are critical in the pathophysiological mechanisms of acute kidney injury (AKI). Here, we investigated the role of interferon regulatory factor three (IRF3) and subsequent activation of the Hippo pathway in inflammatory damage and repair using an in vitro cell model of LPS-induced AKI. LPS caused the phosphorylation and activation of IRF3 in the early stages of sepsis, and activated IRF3 enhanced the production of type I interferon (IFN), resulting in an excessive inflammatory response. Furthermore, LPS generated considerably more inflammatory injury than intended cell death, and IRF3 activation triggered the Hippo pathway, causing a reduction in YAP, which eventually impaired proliferation and repair in surviving renal tubular epithelial cells and exacerbated the development of AKI. In conclusion, IRF3 promoted the development of sepsis-associated AKI (SAKI) by modulating the Hippo pathway.

Emerging role of Hippo pathway in the regulation of hematopoiesis

In various organisms, the Hippo signaling pathway has been identified as a master regulator of organ size determination and tissue homeostasis. The Hippo signaling coordinates embryonic development, tissue regeneration and differentiation, through regulating cell proliferation and survival. The YAP and TAZ (YAP/TAZ) act as core transducers of the Hippo pathway, and they are tightly and exquisitely regulated in response to various intrinsic and extrinsic stimuli. Abnormal regulation or genetic variation of the Hippo pathway causes a wide range of human diseases, including cancer. Recent studies have revealed that Hippo signaling plays a pivotal role in the immune system and cancer immunity. Due to pathophysiological importance, the emerging role of Hippo signaling in blood cell differentiation, known as hematopoiesis, is receiving much attention. A number of elegant studies using a genetically engineered mouse (GEM) model have shed light on the mechanistic and physiological insights into the Hippo pathway in the regulation of hematopoiesis. Here, we briefly review the function of Hippo signaling in the regulation of hematopoiesis and immune cell differentiation. [BMB Reports 2023; 56(8): 417-425].

YAP/TAZ: Molecular pathway and disease therapy

The Yes-associated protein and its transcriptional coactivator with PDZ-binding motif (YAP/TAZ) are two homologous transcriptional coactivators that lie at the center of a key regulatory network of Hippo, Wnt, GPCR, estrogen, mechanical, and metabolism signaling. YAP/TAZ influences the expressions of downstream genes and proteins as well as enzyme activity in metabolic cycles, cell proliferation, inflammatory factor expression, and the transdifferentiation of fibroblasts into myofibroblasts. YAP/TAZ can also be regulated through epigenetic regulation and posttranslational modifications. Consequently, the regulatory function of these mechanisms implicates YAP/TAZ in the pathogenesis of metabolism-related diseases, atherosclerosis, fibrosis, and the delicate equilibrium between cancer progression and organ regeneration. As such, there arises a pressing need for thorough investigation of YAP/TAZ in clinical settings. In this paper, we aim to elucidate the signaling pathways that regulate YAP/TAZ and explore the mechanisms of YAP/TAZ-induce diseases and their potential therapeutic interventions. Furthermore, we summarize the current clinical studies investigating treatments targeting YAP/TAZ. We also address the limitations of existing research on YAP/TAZ and propose future directions for research. In conclusion, this review aims to provide fresh insights into the signaling mediated by YAP/TAZ and identify potential therapeutic targets to present innovative solutions to overcome the challenges associated with YAP/TAZ.

Effect of Jiawei Tongqiao Huoxue decoction in basilar artery dolichoectasia mice through yes-associated protein/transcriptional Co-activator with PDZ-binding motif pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The Jiawei Tongqiao Huoxue decoction (JTHD), composed of Acorus calamus var. angustatus Besser, Paeonia lactiflora Pall., Conioselinum anthriscoides 'Chuanxiong', Prunus persica (L.) Batsch, Ziziphus jujuba Mill., Carthamus tinctorius L., Pueraria montana var. lobata (Willd.) Maesen & S.M.Almeida ex Sanjappa & Predeep, Zingiber officinale Roscoe, Leiurus quinquestriatus, and Moschus berezovskii Flerov, was developed based on Tongqiao Huoxue decoction in Wang Qingren's "Yilin Gaicuo" in the Qing Dynasty. It has the effect of improving not only the blood flow velocity of vertebral and basilar arteries but also the blood flow parameters and wall shear stress. Especially in recent years, the potential efficacy of traditional Chinese medicine (TCM) for the treatment of basilar artery dolichoectasia (BAD) has attracted great attention as there are still no specific remedies for this disease. However, its molecular mechanism has not been elucidated. To identify the potential mechanisms of JTHD will help to intervene BAD and provide a reference for its clinical application.

AIM OF THE STUDY

This study aims to establish a mouse model of BAD and explore the mechanism of JTHD regulating yes-associated protein/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) pathway for attenuating BAD mice development.

MATERIALS AND METHODS

Sixty post-modeling C57/BL6 female mice were randomly divided into sham-operated, model, atorvastatin calcium tablet, low-dose JTHD, and high-dose JTHD groups. After 14 days of modeling, the pharmacological intervention was given for 2 months. Then, JTHD was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS). ELISA was utilized to detect the changes in vascular endothelial growth factor (VEGF) and lipoprotein a (Lp-a) in serum. EVG staining was conducted to observe the pathological changes of blood vessels. TUNEL method was employed to detect the apoptosis rate of vascular smooth muscle cells (VSMCs). Micro-CT and ImagePro Plus software were used to observe and calculate the tortuosity index, lengthening index, percentage increase in vessel diameter, and tortuosity of the basilar artery vessels in mice. Western blot analysis was performed to detect the expression levels of YAP and TAZ proteins in the vascular tissues of mice.

RESULTS

Many effective compounds such as choline, tryptophan, and leucine with anti-inflammation and vascular remodeling were identified in the Chinese medicine formula by LC-MS analysis. The serum levels of VEGF in the model mice decreased significantly while the levels of Lp-a increased obviously compared with those in the sham-operated group. The intima-media of the basilar artery wall showed severe disruption of the internal elastic layer, atrophy of the muscular layer, and hyaline changes of the connective tissue. Apoptosis of VSMCs added. Dilatation, elongation, and tortuosity of the basilar artery became notable, and tortuosity index, lengthening index, percentage increase in vessel diameter, and bending angle remarkably improved. The expression levels of YAP and TAZ protein in blood vessels elevated conspicuously (P < 0.05, P < 0.01). JTHD group markedly reduced the lengthening, bending angle, percentage increase in vessel diameter, and tortuosity index of basilar artery compared with the model group after 2 months of pharmacological intervention. The group also decreased the secretion of Lp-a and increased the content of VEGF. It inhibited the destruction of the internal elastic layer, muscular atrophy, and hyaline degeneration of connective tissue in basilar artery wall. The apoptosis of VSMCs was decreased, and the expression levels of YAP and TAZ proteins were abated (P < 0.05, P < 0.01).

CONCLUSIONS

The mechanism of inhibition of basilar artery elongation, dilation, and tortuosity by JTHD, which has various anti-BAD effective compound components, may be related to the reduction in VSMCs apoptosis and downregulation of YAP/TAZ pathway expression.

The hippo kinases MST1/2 in cardiovascular and metabolic diseases: A promising therapeutic target option for pharmacotherapy

Cardiovascular diseases (CVDs) and metabolic disorders are major components of noncommunicable diseases, causing an enormous health and economic burden worldwide. There are common risk factors and developmental mechanisms among them, indicating the far-reaching significance in exploring the corresponding therapeutic targets. MST1/2 kinases are well-established proapoptotic effectors that also bidirectionally regulate autophagic activity. Recent studies have demonstrated that MST1/2 influence the outcome of cardiovascular and metabolic diseases by regulating immune inflammation. In addition, drug development against them is in full swing. In this review, we mainly describe the roles and mechanisms of MST1/2 in apoptosis and autophagy in cardiovascular and metabolic events as well as emphasis on the existing evidence for their involvement in immune inflammation. Moreover, we summarize the latest progress of pharmacotherapy targeting MST1/2 and propose a new mode of drug combination therapy, which may be beneficial to seek more effective strategies to prevent and treat CVDs and metabolic disorders.

The role of 14-3-3 in the progression of vascular inflammation induced by lipopolysaccharide

OBJECTIVE

To explore the role of 14-3-3 protein and the Hippo and yes-associated protein 1 (YAP) signaling pathway in lipopolysaccharide (LPS)-induced vascular inflammation.

METHODS

Human umbilical vein endothelial cells (HUVECs) and C57B6 mice were treated with LPS to establish cell and animal models of vascular inflammation. Lentiviral transfection, Western blot, qPCR, immunofluorescence, immunohistochemistry, co-immunoprecipitation, and enzyme-linked immunosorbent assays were used to measure inflammatory factors and expression of 14-3-3 protein and phosphorylation of YAP at S127. HUVECs and C57B6 mice were pretreated with a YAP inhibitor, Verteporfin, to observe changes in YAP expression and downstream vascular inflammation.

RESULTS

LPS induced acute and chronic inflammatory responses in HUVECs and mice and upregulated the expression of several inflammatory factors. LPS also induced expression of 14-3-3 protein and phosphorylation of YAP at S127 in response to acute vascular inflammation and downregulated these markers in response to chronic vascular inflammation. Verteporfin reduced these LPS-induced effects on vascular inflammation.

CONCLUSION

In chronic vascular inflammation, 14-3-3 protein is downregulated, which promotes inflammation by increasing Hippo/YAP nuclear translocation.

Biophysical cues to improve the immunomodulatory capacity of mesenchymal stem cells: The progress and mechanisms

Mesenchymal stem cells (MSCs) can maintain immune homeostasis and many preclinical trials with MSCs have been carried out around the world. In vitro culture of MSCs has been found to result in the decline of immunomodulatory capacity, migration and proliferation. To address these problems, simulating the extracellular environment for preconditioning of MSCs is a promising and inexpensive method. Biophysical cues in the external environment that MSCs are exposed to have been shown to affect MSC migration, residency, differentiation, secretion, etc. We review the main ways in which MSCs exert their immunomodulatory ability, and summarize recent advances in mechanical preconditioning of MSCs to enhance immunomodulatory capacity and related mechanical signal sensing and transduction mechanisms.

DNAJB4 promotes triple-negative breast cancer cell apoptosis via activation of the Hippo signaling pathway

INTRODUCTION

Triple-negative breast cancer (TNBC) is currently the most malignant subtype of breast cancer without effective targeted therapies. DNAJB4 (Dnaj heat shock protein family (Hsp40) member B4) is a member of the human heat shock protein family (Hsp40). The clinical significance of DNAJB4 in breast cancer has been reported in our previous study. However, the biological function of DNAJB4 in TNBC cell apoptosis remains unclear to date.

METHODS

The expression of DNAJB4 in normal breast cells, breast cancer cells, four-paired TNBC tissues, and adjacent noncancerous tissues was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assay. The role of DNAJB4 in TNBC cell apoptosis was investigated using a number of gain- and loss-of-function in vitro and in vivo assays. The underlying molecular mechanisms in TNBC cell apoptosis were elucidated via Western blot assay.

RESULTS

DNAJB4 expression was significantly downregulated in TNBC tissues and cell lines. DNAJB4 knockdown inhibited TNBC cell apoptosis and promoted tumorigenicity in vitro and in vivo, but DNAJB4 overexpression resulted in the opposite. Mechanically, DNAJB4 knockdown inhibited TNBC cell apoptosis through suppression of the Hippo signaling pathway, and the result was reversed after DNAJB4 overexpression.

CONCLUSIONS

DNAJB4 promotes TNBC cell apoptosis by activating the Hippo signaling pathway. Therefore, DNAJB4 may act as a prognostic biomarker and therapeutic target for TNBC.

Vestigial-like 1 (VGLL1): An ancient co-transcriptional activator linking wing, placenta, and tumor development

Vestigial-like 1 (VGLL1) is a recently discovered driver of proliferation and invasion that is expressed in many aggressive human malignancies and is strongly associated with poor prognosis. The VGLL1 gene encodes for a co-transcriptional activator that shows intriguing structural similarity to key activators in the hippo pathway, providing important clues to its functional role. VGLL1 binds to TEADs in an analogous fashion to YAP1 but appears to activate a distinct set of downstream gene targets. In mammals, VGLL1 expression is found almost exclusively in placental trophoblasts, cells that share many hallmarks of cancer. Due to its role as a driver of tumor progression, VGLL1 has become a target of interest for potential anticancer therapies. In this review, we discuss VGLL1 from an evolutionary perspective, contrast its role in placental and tumor development, summarize the current knowledge of how signaling pathways can modulate VGLL1 function, and discuss potential approaches for targeting VGLL1 therapeutically.

Electroacupuncture regulates microglia polarization via lncRNA-mediated hippo pathway after ischemic stroke

Microglia polarization and microglia-mediated inflammation play a crucial role in the development of ischaemic brain injury. Electroacupuncture (EA) has the function of anti-inflammatory, which has been thoroughly validated and utilized to treat ischemic brain damage. The fundamental mechanism by which EA alleviates ischemic brain damage by decreasing microglia polarization and microglia-mediated inflammation, however, remains unknown. In the current study, the activation of microglia and inflammatory cytokines was analyzed to confirm the anti-inflammatory function of EA in middle cerebral artery occlusion (MCAO) rats. Whole-transcriptome sequencing was used to examine the differentially expressed lncRNAs in the control, MCAO, and MCAO +EA groups. Our findings demonstrated that EA treatment reduced microglia activation and inflammatory cytokine production. In addition, there are 44 lncRNAs were found significantly different in three groups, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway of the predicted targets of these lncRNAs suggested that the Hippo pathway may contribute to the development of ischaemic brain injury and to the anti-inflammatory function of EA. Moreover, our data showed that lncRNA TCONS_00022826 (Lnc826) was upregulated in MCAO group, whereas blocked by EA treatment. Furthermore, in vitro OGD cell model data showed that Lnc826 promoted M1 polarization of microglia by regulating the Hippo pathway. Our data suggested that regulating microglia polarization via Lnc826-mediated hippo pathway is a possible mechanism of the EA treatment on ischemic brain injury.

Negative effects of heat stress on ovarian tissue in female rabbit

Numerous studies have highlighted the role of miRNA in the deformation and necrosis of cells of ovarian tissue caused by heat stress (HS), which ultimately affects ovarian function. Although the role of small RNAs has been investigated in alterations in ovarian tissue functioning in response to HS, the expression profile of ovarian miRNA has been explored to a lesser extent. In this study, female rabbits were subject to HS treatment by using electrical heater. The current work demonstrated that HS could significantly change physiological performance of female rabbits including body weight, rectal temperature and relative ovary weight, and significantly reduce serum IL-2, IL-8, CAT, and GSH-Px concentrations by enzyme-linked immunosorbent assay (ELISA) technique. As a result, an increase in apoptosis in ovarian cells, as well as unhealthy follicles, were observed by Hematoxylin-eosin (HE) and TUNEL staining. Additionally, small RNA-seq revealed changes in the miRNA expression profile of rabbit ovaries under HS. Five hundred fourteen miRNAs were obtained including known miRNAs 442 and novel miRNAs 72. Among these miRNAs, 23 miRNAs were significantly expressed under HS. Eleven differentially expressed miRNAs (DE miRNAs) and 9 their predicted targets were confirmed by qPCR, which were expected miRNA-mRNA negative regulation pattern. Among the DE miRNAs and targets, miR-141-39 may target COQ6, miR-449a-5p and miR-34c-5p may control RFC5 and RTN2 together, miR-449a-5p may target ACADVL, miR-34c-5p potentially targets Bcl-2 and miR-196b-5p potentially regulates CASK and HOXB6. Thus, the current work suggested the negative effects of HS on the ovarian tissue of female rabbits, and in conclusion these changes could be caused by decreased serum IL-2, IL-8, CAT and GSH-Px levels, increased ovarian apoptosis, and changed the expression of miRNAs.

The crosstalk between LINC01089 and hippo pathway inhibits osteosarcoma progression

INTRODUCTION

Osteosarcoma is the most common malignancy in children, with high morbidity worldwide. Researches indicated that long non-coding RNAs (lncRNAs) played crucial roles in various cancers. Nevertheless, study investigating lncRNA long intergenic non-protein coding RNA 1089 (LINC01089) in osteosarcoma is extremely rare. Thus, the research of LINC01089 is of great significance.

MATERIALS AND METHODS

qRT-PCR and western blot were done to test the expression of RNAs and proteins in osteosarcoma cells. Functional assays were carried out to evaluate biological behaviors of hFOB1.19 and osteosarcoma cells with or without LINC01089 knockdown and overexpression. In vitro and in vivo experiments in a rescue manner were performed to reveal the influences of LINC01089 and Hippo pathway on osteosarcoma cell phenotype and tumor growth.

RESULTS

LINC01089 was down-regulated in osteosarcoma cells and overexpressing LINC01089 was validated to restrain cell growth in vitro and tumor growth in vivo. Additionally, silencing LINC01089 could exacerbate cell malignant behaviors. Correlation of LINC01089 and Hippo pathway was proved. Overexpressing LINC01089 could activate Hippo pathway to exert antitumor effects.

CONCLUSION

LINC01089 could restrain the progression of osteosarcoma through activating Hippo pathway.

Pleiotropic effects of DCLK1 in cancer and cancer stem cells

Doublecortin-like kinase 1 (DCLK1), a protein molecule, has been identified as a tumor stem cell marker in the cancer cells of gastrointestinal, pancreas, and human colon. DCLK1 expression in cancers, such as breast carcinoma, lung carcinoma, hepatic cell carcinoma, tuft cells, and human cholangiocarcinoma, has shown a way to target the DCLK1 gene and downregulate its expression. Several studies have discussed the inhibition of tumor cell proliferation along with neoplastic cell arrest when the DCLK1 gene, which is expressed in both cancer and normal cells, was targeted successfully. In addition, previous studies have shown that DCLK1 plays a vital role in various cancer metastases. The correlation of DCLK1 with numerous stem cell receptors, signaling pathways, and genes suggests its direct or an indirect role in promoting tumorigenesis. Moreover, the impact of DCLK1 was found to be related to the functioning of an oncogene. The downregulation of DCLK1 expression by using targeted strategies, such as embracing the use of siRNA, miRNA, CRISPR/Cas9 technology, nanomolecules, specific monoclonal antibodies, and silencing the pathways regulated by DCLK1, has shown promising results in both in vitro and in vivo studies on gastrointestinal (GI) cancers. In this review, we will discuss about the present understanding of DCLK1 and its role in the progression of GI cancer and metastasis.

The Hippo Pathway Effector Transcriptional Co-activator With PDZ-Binding Motif Correlates With Clinical Prognosis and Immune Infiltration in Colorectal Cancer

The transcriptional co-activator with PDZ-binding motif (TAZ) is a downstream effector of the Hippo pathway. It has been identified as an oncogene in certain tumor types; however, the function and role of TAZ in colorectal cancer (CRC) has not been illustrated. Here, we aimed to analyze the expression and role of TAZ in CRC. In this study, we investigated the expression level of TAZ in 127 CRC and matched adjacent normal tissues by immunohistochemistry (IHC) and analyzed its correlation with clinicopathological characteristics in CRC. Moreover, we further analyzed the role of TAZ in the CRC-associated immunology using integrative bioinformatic analyses. The cBioPortal and WebGestalt database were used to analyze the co-expressed genes and related pathways of TAZ in CRC by gene ontology (GO) and KEGG enrichment analyses. Meanwhile, the correlations between TAZ and the infiltrating immune cells and gene markers were analyzed by TIMER database. Our study revealed that TAZ expression is higher in CRC tissues than in matched adjacent non-tumor tissues. In addition, CRC patients with higher TAZ expression demonstrated poor overall survival (OS) and recurrent-free survival rates as compared to CRC patients with lower expression of TAZ. Furthermore, the TAZ expression was identified to closely associate with the immune infiltration of CD4 + T, CD8 + T, and B cells. Taken together, our findings suggest that TAZ may serve as a promising prognostic biomarker and therapeutic target in CRC.

Effect of TDP43-CTFs35 on Brain Endothelial Cell Functions in Cerebral Ischemic Injury

Pathological changes in the brain endothelium play an important role in the progression of ischemic stroke and the compromised BBB under ischemic stroke conditions cause neuronal damage. However, the pathophysiological mechanisms of the BBB under normal conditions and under ischemic stroke conditions have not been fully elucidated. The present study demonstrated that knockdown of TAR DNA-binding protein 43 (TDP-43) or overexpression of TDP43-CTFs35 inhibited tight junction protein expression, and mammalian sterile-20-like 1/2 (MST1/2) and YES-associated protein (YAP) phosphorylation in brain ECs and suppressed brain EC migration in vitro. The cytoplasmic TDP43-CTFs35 level was increased in brain ECs 24 h and 72 h after MCAO, but it disappeared 1 week after cerebral ischemia. The expression of tight junction proteins was also significantly deceased 24 h after MCAO and then gradually recovered at 72 h and 1 week after MCAO. The level of YAP phosphorylation was first significantly decreased 24 h after MCAO and then increased 72 h and 1 week after MCAO, accompanied by nuclear YAP translocation. The underlying mechanism is TDP43-CTFs35-mediated inhibition of Hippo signaling pathway activity through the dephosphorylation of MST1/2, which leads to the inhibition of YAP phosphorylation and the subsequent impairment of brain EC migration and tight junction protein expression. This study provides new insights into the mechanisms of brain vascular EC regulation, which may impact on BBB integrity after cerebral ischemic injury.

Hippo signaling pathway and respiratory diseases

The hippo signaling pathway is a highly conserved evolutionary signaling pathway that plays an important role in regulating cell proliferation, organ size, tissue development, and regeneration. Increasing evidences consider that the hippo signaling pathway is involved in the process of respiratory diseases. Hippo signaling pathway is mainly composed of mammalian STE20-like kinase 1/2 (MST1/2), large tumor suppressor 1/2 (LATS1/2), WW domain of the Sav family containing protein 1 (SAV1), MOB kinase activator 1 (MOB1), Yes-associated protein (YAP) or transcriptional coactivator with PDZ-binding motif (TAZ), and members of the TEA domain (TEAD) family. YAP is the cascade effector of the hippo signaling pathway. The activation of YAP promotes pulmonary arterial vascular smooth muscle cells (PAVSMCs) proliferation, which leads to pulmonary vascular remodeling; thereby the pulmonary arterial hypertension (PAH) is aggravated. While the loss of YAP leads to high expression of inflammatory genes and the accumulation of inflammatory cells, the pneumonia is consequently exacerbated. In addition, overexpressed YAP promotes the proliferation of lung fibroblasts and collagen deposition; thereby the idiopathic pulmonary fibrosis (IPF) is promoted. Moreover, YAP knockout reduces collagen deposition and the senescence of adult alveolar epithelial cells (AECs); hence the IPF is slowed. In addition, hippo signaling pathway may be involved in the repair of acute lung injury (ALI) by promoting the proliferation and differentiation of lung epithelial progenitor cells and intervening in the repair of pulmonary capillary endothelium. Moreover, the hippo signaling pathway is involved in asthma. In conclusion, the hippo signaling pathway is involved in respiratory diseases. More researches are needed to focus on the molecular mechanisms by which the hippo signaling pathway participates in respiratory diseases.

LATS1 is a central signal transmitter for achieving full type-I interferon activity

Interferons (IFNs) have broad-spectrum antiviral activity to resist virus epidemic. However, IFN antiviral efficacy needs to be greatly improved. Here, we reveal that LATS1 is a vital signal transmitter governing full type-I IFN (IFN-I) signaling activity. LATS1 constitutively binds with the IFN-I receptor IFNAR2 and is rapidly tyro-phosphorylated by Tyk2 upon IFN-I engagement. Tyro-phosphorylation of LATS1 promotes LATS1 activation and YAP degradation, thereby promoting IFN-mediated antiproliferation activity. Moreover, activated LATS1 translocates into the nucleus and induces CDK8-Ser62 phosphorylation, which in turn phosphorylates STAT1 at Ser727 and induces full IFN-I antiviral activity. LATS1 deficiency restricts in vivo IFN-I signaling and attenuates host antiviral immune response. Our study identifies IFN-I as a previously unidentified extracellular diffusible ligand signal for activation of the Hippo core LATS1 pathway and reveals Tyk2-LATS1-CDK8 as a complete signaling cascade controlling full IFN-I activity.

cGAS/STING signaling in the regulation of rheumatoid synovial aggression

Background

Fibroblast-like synoviocytes (FLSs) play a critical role in promoting synovial aggression and joint destruction in rheumatoid arthritis (RA). Cyclic GMP-AMP synthase (cGAS)/stimulator of interferon gene (STING) signaling plays an important role in controlling a series of cellular biological processes. However, it is still unclear whether cGAS/STING signaling regulates rheumatoid synovial aggression.

Methods

Cell migration and invasion were detected using a Transwell chamber. Gene expression was measured using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and protein expression was detected by western blotting. Reactive oxygen species (ROS) levels were measured by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) probe. F-actin staining and immunofluorescence assays were used to investigate lamellipodia formation and nuclear translocation, respectively. A severe combined immunodeficiency (SCID) mouse model was established to observe the migration and invasion of RA FLSs in vivo.

Results

Our results showed that cytosolic double-stranded DNA (dsDNA)-induced cGAS/STING activation promoted the in vitro migration and invasion of RA FLSs. Moreover, RA FLSs treated with cGAS or STING short hairpin RNA (shRNA) exhibited reduced invasion into cartilage in the SCID model. Mechanistically, we determined that cGAS/STING activation leads to increased mitochondrial ROS levels, and thereby increases phosphorylation of mammalian sterile 20-like kinase 1 (MST1), a core component of the Hippo pathway, subsequently promoting activation of forkhead box1 (FOXO1). MST1 and FOXO1 knockdown also diminished the migration and invasion of RA FLSs.

Conclusions

Our findings suggest that cGAS/STING signaling has an important role in regulating rheumatoid synovial aggression and that targeting cGAS/STING may represent a novel potential therapy for RA.

Purification, Chemical Characterization and Immunomodulatory Activity of a Sulfated Polysaccharide from Marine Brown Algae Durvillaea antarctica

An immunomodulatory polysaccharide (DAP4) was extracted, purified, and characterized from Durvillaea antarctica. The results of chemical and spectroscopic analyses demonstrated that the polysaccharide was a fucoidan, and was mainly composed of (1→3)-α-l-Fucp and (1→4)-α-l-Fucp residues with a small degree of branching at C-3 of (1→4)-α-l-Fucp residues. Sulfate groups were at C-4 of (1→3)-α-l-Fucp, C-2 of (1→4)-α-l-Fucp and minor C-6 of (1→4)-β-d-Galp. Small amounts of xylose and galactose exist in the forms of β-d-Xylp-(1→ and β-d-Gal-(1→. The immunomodulatory activity of DAP4 was measured on RAW 264.7 cells, the results proved that DAP4 exhibited excellent immunomodulatory activities, such as promoted the proliferation of spleen lymphocytes, increased NO production, as well as enhanced phagocytic of macrophages. Besides, DAP4 could also produce better enhancement on the vitality of NK cells. For the high immunomodulatory activity, DAP4 might be a potential source of immunomodulatory fucoidan with a novel structure.

Inhibition of Transient Receptor Potential Vanilloid 4 (TRPV4) Mitigates Seizures

Astrocytes are critical regulators of the immune/inflammatory response in several human central nervous system (CNS) diseases. Emerging evidence suggests that dysfunctional astrocytes are crucial players in seizures. The objective of this study was to investigate the role of transient receptor potential vanilloid 4 (TRPV4) in 4-aminopyridine (4-AP)-induced seizures and the underlying mechanism. We also provide evidence for the role of Yes-associated protein (YAP) in seizures. 4-AP was administered to mice or primary cultured astrocytes. YAP-specific small interfering RNA (siRNA) was administered to primary cultured astrocytes. Mouse brain tissue and surgical specimens from epileptic patient brains were examined, and the results showed that TRPV4 was upregulated, while astrocytes were activated and polarized to the A1 phenotype. The levels of glial fibrillary acidic protein (GFAP), cytokine production, YAP, signal transducer activator of transcription 3 (STAT3), intracellular Ca2+([Ca2+]i) and the third component of complement (C3) were increased in 4-AP-induced mice and astrocytes. Perturbations in the immune microenvironment in the brain were balanced by TRPV4 inhibition or the manipulation of [Ca2+]i in astrocytes. Knocking down YAP with siRNA significantly inhibited 4-AP-induced pathological changes in astrocytes. Our study demonstrated that astrocytic TRPV4 activation promoted neuroinflammation through the TRPV4/Ca2+/YAP/STAT3 signaling pathway in mice with seizures. Astrocyte TRPV4 inhibition attenuated neuroinflammation, reduced neuronal injury, and improved neurobehavioral function. Targeting astrocytic TRPV4 activation may provide a promising therapeutic approach for managing epilepsy.

Specific targeting of cancer stem cells by immunotherapy: A possible stratagem to restrain cancer recurrence and metastasis

Cancer stem cells (CSCs), the tumor-initiating cells playing a crucial role in cancer progression, recurrence, and metastasis, have the intrinsic property of self-renewal and therapy resistance. The tumorigenic properties of these cells include generation of cellular heterogeneity and immuno-suppressive tumor microenvironment (TME), conferring them the capability to resist a variety of anti-cancer therapeutics. Further, CSCs possess several unique immunological properties that help them escape recognition by the innate and adaptive immune system and shape a TME into a pro-tumorigenic and immunosuppressive landscape. In this context, immunotherapy is considered one of the best therapeutic options for eliminating CSCs to halt cancer recurrence and metastasis. In this review, we discuss the various immunomodulatory properties of CSCs and the interaction of CSCs with the immune system enabling immune evasion. In addition, we also highlight the present research update on immunotherapeutic targeting of CSCs and the possible further scope of research on this topic. We believe that a deeper understanding of CSCs' immunological properties and the crosstalk between CSCs and the immune system can develop better innovative immune-therapeutics and enhance the efficacy of current therapy-resistant cancer treatments.

Identification of a Quinone Derivative as a YAP/TEAD Activity Modulator from a Repurposing Library

The transcriptional regulators YAP (Yes-associated protein) and TAZ (transcriptional co-activator with PDZ-binding motif) are the major downstream effectors in the Hippo pathway and are involved in cancer progression through modulation of the activity of TEAD (transcriptional enhanced associate domain) transcription factors. To exploit the advantages of drug repurposing in the search of new drugs, we developed a similar approach for the identification of new hits interfering with TEAD target gene expression. In our study, a 27-member in-house library was assembled, characterized, and screened for its cancer cell growth inhibition effect. In a secondary luciferase-based assay, only seven compounds confirmed their specific involvement in TEAD activity. IA5 bearing a p-quinoid structure reduced the cytoplasmic level of phosphorylated YAP and the YAP–TEAD complex transcriptional activity and reduced cancer cell growth. IA5 is a promising hit compound for TEAD activity modulator development.

ROCK1 mechano-signaling dependency of human malignancies driven by TEAD/YAP activation

Rho family mechano-signaling through the actin cytoskeleton positively regulates physiological TEAD/YAP transcription, while the evolutionarily conserved Hippo tumor suppressor pathway antagonizes this transcription through YAP cytoplasmic localization/degradation. The mechanisms responsible for oncogenic dysregulation of these pathways, their prevalence in tumors, as well as how such dysregulation can be therapeutically targeted are not resolved. We demonstrate that p53 DNA contact mutants in human tumors, indirectly hyperactivate RhoA/ROCK1/actomyosin signaling, which is both necessary and sufficient to drive oncogenic TEAD/YAP transcription. Moreover, we demonstrate that recurrent lesions in the Hippo pathway depend on physiological levels of ROCK1/actomyosin signaling for oncogenic TEAD/YAP transcription. Finally, we show that ROCK inhibitors selectively antagonize proliferation and motility of human tumors with either mechanism. Thus, we identify a cancer driver paradigm and a precision medicine approach for selective targeting of human malignancies driven by TEAD/YAP transcription through mechanisms that either upregulate or depend on homeostatic RhoA mechano-signaling.

Yorkie Negatively Regulates the Expression of Antimicrobial Proteins by Inducing Cactus Transcription in Prawns Macrobrachium nipponense

The Hippo signaling pathway controls organ size and immune system in Drosophila and mammals. Yorkie acts as a transcriptional co-activator in the Hippo pathway and cross-talks with other essential pathways. In this study, a Yorkie gene and two Cactus isoforms (designated as MnYorkie, MnCactus-a, and MnCactus-b, respectively) were isolated and characterized from oriental river prawns (Macrobrachium nipponense). Results showed that MnYorkie includes 1620 bp open reading frame and encodes a protein of 539 amino acids (aa). MnCactus-a (377 aa) and MnCactus-b (471 aa) were produced by alternative splicing. MnYorkie and MnCactus were continuously expressed in all selected tissues. Upon Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Vibrio parahaemolyticus stimulation, the mRNA levels of MnYorkie and MnCactus in hemocytes and intestines underwent time-dependent enhancement. RNA interference studies showed that MnYorkie silencing remarkably downregulated the transcription of MnCactus but upregulated the expression of seven immune-related genes. In addition, MnYorkie silencing in vivo decreased the susceptibility of prawns to bacterial challenge. After S. aureus and V. parahaemolyticus infection, the survival rate of prawns increased significantly from 2 to 6 days, which corresponded to the period of MnYorkie knockdown. All these findings suggested that MnYorkie in the Hippo pathway might exhibit remarkable biological roles in the immune defense of M. nipponense by negatively regulating the expression of immune-related genes and promoting the transcription of MnCactus.

The Hippo signaling component LATS2 enhances innate immunity to inhibit HIV-1 infection through PQBP1-cGAS pathway

As the most primordial signaling pathway in animal physiology, the Hippo pathway and innate immunity play crucial roles not only in sensing cellular conditions or infections, but also in various metabolite homeostasis and tumorigenesis. However, the correlation between cellular homeostasis and antiviral defense is not well understood. The core kinase LATS1/2, could either enhance or inhibit the anti-tumor immunity in different cellular contexts. In this study, we found that LATS2 can interact with PQBP1, the co-factor of cGAS, thus enhanced the cGAS-STING mediated innate immune response to HIV-1 challenge. LATS2 was observed to upregulate type-I interferon (IFN-I) and cytokines in response to HIV-1 reverse-transcribed DNA and inhibited HIV-1 infection. Due to the involvement of PQBP1, the function of LATS2 in regulating cGAS activity is not relying on the downstream YAP/TAZ as that in the canonical Hippo pathway. The related kinase activity of LATS2 was verified, and the potential phosphorylation site of PQBP1 was identified. Our study established a novel connection between Hippo signaling and innate immunity, thus may provide new potential intervention target on antiviral therapeutics.

Loss-of-function of the hippo transducer TAZ reduces mammary tumor growth through a myeloid-derived suppressor cell-dependent mechanism

TAZ, one of the key effectors in the Hippo pathway, is often dysregulated in breast cancer, leading to cancer stemness, survival, and metastasis. However, the mechanistic bases of these tumor outcomes are incompletely understood and even less is known about the potential role played by the non-malignant cellular constituents of the tumor microenvironment (TME). Here, we revealed an inverse correlation between TAZ expression and survival in triple-negative breast cancer (TNBC), but not other subtypes of breast cancer. We found that TAZ knockdown in two murine TNBC tumor cell line models significantly inhibited tumor growth and metastasis in immune competent but not immune deficient hosts. RNA-seq analyses identified substantial alterations in immune components in TAZ knockdown tumors. Using mass cytometry analysis, we found that TAZ-deficiency altered the immune landscape of the TME leading to significant reductions in immune suppressive populations, namely myeloid-derived suppressor cells (MDSCs) and macrophages accompanied by elevated CD8⁺ T cell/myeloid cell ratios. Mechanistic studies demonstrated that TAZ-mediated tumor growth was MDSC-dependent in that MDSC depletion led to reduced tumor growth in control, but not TAZ-knockdown tumor cells. Altogether, we identified a novel non-cancer cell-autonomous mechanism by which tumor-intrinsic TAZ expression aids tumor progression. Thus, our findings advance an understanding of the crosstalk between tumor-derived TAZ expression and the immune contexture within the TME, which may lead to new therapeutic interventions for TNBC or other TAZ-driven cancers.

Whole-exome sequencing in eccrine porocarcinoma indicates promising therapeutic strategies

Malignant sweat gland tumours are rare, with the most common form being Eccrine porocarcinoma (EP). To investigate the mutational landscape of EP, we performed whole-exome sequencing (WES) on 14 formalin-fixed paraffin-embedded samples of matched primary EP and healthy surrounding tissue. Mutational profiling revealed a high overall median mutation rate. This was attributed to signatures of mutational processes related to ultraviolet (UV) exposure, APOBEC enzyme dysregulation, and defective homologous double-strand break repair. All of these processes cause genomic instability and are implicated in carcinogenesis. Recurrent driving somatic alterations were detected in the EP candidate drivers TP53, FAT2, CACNA1S, and KMT2D. The analyses also identified copy number alterations and recurrent gains and losses in several chromosomal regions including that containing BRCA2, as well as deleterious alterations in multiple HRR components. In accordance with this reduced or even a complete loss of BRCA2 protein expression was detected in 50% of the investigated EP tumours. Our results implicate crucial oncogenic driver pathways and suggest that defective homologous double-strand break repair and the p53 pathway are involved in EP aetiology. Targeting of the p53 axis and PARP inhibition, and/or immunotherapy may represent promising treatment strategies.

YAP/Hippo Pathway and Cancer Immunity: It Takes Two to Tango

Hippo pathway with its main molecule YAP is a crucial pathway for development, tissue homeostasis, wound healing, tissue regeneration, and cancer. In this review, we discuss the multiple effects of the YAP/Hippo pathway in the immune system and cancer. We analyzed a series of effects: extracellular vesicles enhanced immunity through inhibition of LATS1/2, ways of modulation of the tumor microenvironment, YAP- and TAZ-mediated upregulation of PDL1, high expression of YAP and PDL1 in EGFR-TKI-resistant cells, enhanced YAP activity in inflammation, and the effect of the Hippo pathway on T cells, B cells, Tregs, macrophages, and myeloid-derived suppressor cells (MDSCs). These pleiotropic effects render the YAP and Hippo pathway a key pathway for exploitation in the future, in order to enhance our immunotherapy treatment strategies in oncology.

Statins downregulate YAP and TAZ and exert anti-cancer effects in canine mammary tumour cells

Canine mammary tumours (CMTs) are the most common neoplasms in intact bitches, and few chemotherapeutic options are available for highly invasive and metastatic tumours. Recent studies have shown the potential involvement of dysregulated Hippo signalling in CMT development and progression. Statins can activate the Hippo pathway by blocking protein geranylgeranylation (GGylation), resulting in decreased expression and activity of the transcriptional co-activators YAP and TAZ. In this study, we therefore sought to determine if statins could exert anti-cancer effects in CMT cells. Our results demonstrate that Atorvastatin and Fluvastatin are cytotoxic to two CMT cell lines (CMT9 and CMT47), with ED50 values ranging from 0.95 to 23.5 μM. Both statins acted to increase apoptosis and promote cell cycle arrest. Both statins also decreased YAP and TAZ expression and reduced the mRNA levels of key Hippo transcriptional target genes known to be involved in breast cancer progression and chemoresistance (CYR61, CTGF and RHAMM). Moreover, both statins effectively inhibited cell migration and anchorage independent growth, but did not influence matrix invasion. Taken together, our results demonstrate for the first time that statins act upon the Hippo pathway in CMT cells to counteract several molecular and cellular hallmarks of cancer. These findings suggest that targeting the Hippo pathway with statins represents a novel and promising approach for the treatment canine mammary gland cancers.

miR-92a-3p Promoted EMT via Targeting LATS1 in Cervical Cancer Stem Cells

miR-92a-3p (microRNA-92a-3p) has been reported to be dysregulated in several cancers, and as such, it is considered to be a cancer-related microRNA. However, the influence of miR-92a-3p on biological behaviors in cervical cancer (CC) still remains unclear. Quantitative real-time PCR was used to detect miR-92a-3p levels in CC stem cells. Here, Cell Counting Kit-8 (CCK8) assay, Transwell cell invasion assay and flow cytometry assay were used to characterize the effects that miR-92a-3p and large tumor suppressor l (LATS1) had on proliferation, invasion and cell cycle transition. The luciferase reporter gene assay was used to verify the targeting relationship between miR-92a-3p and LATS1. Western Blotting was used to investigate the related signaling pathways and proteins. Data from The Cancer Genome Atlas (TCGA) showed that miR-92a-3p was upregulated in CC tissues and closely associated with overall survival. miR-92a-3p promoted proliferation, invasion and cell cycle transition in CC stem cells. The luciferase reporter assay showed that miR-92a-3p bound to the 3′-untranslated region (3′-UTR) of the LATS1 promoter. LATS1 inhibited proliferation, invasion and cell cycle transition. Results measured by Western Blotting showed that LATS1 downregulated expressions of transcriptional co-activator with PDZ-binding motif (TAZ), vimentin and cyclin E, but upregulated the expression of E-cadherin. Re-expression of LATS1 partly reversed the effects of miR-92a-3p on proliferation, invasion and cell cycle transition, as well as on TAZ, E-cadherin, vimentin, and cyclin E. miR-92a-3p promoted the malignant behavior of CC stem cells by targeting LATS1, which regulated TAZ and E-cadherin.

USP21 regulates Hippo signaling to promote radioresistance by deubiquitinating FOXM1 in cervical cancer

The ectopic expression of ubiquitin-specific peptidase 21 (USP21) is common in different types of cancer. However, its relationship with radio-sensitivity in cervical cancer (CC) remains unclear. In this study, we aimed to uncover the effect of USP21 on CC radio-resistance and its underlying mechanism. Our results showed that the expression of USP21 was markedly increased in CC tissues of radio-resistant patients and CC cells treated with radiation. Besides, knockdown of USP21 restrained the survival fractions, and facilitated apoptosis of CC cells in the absence or presence of radiation. Additionally, USP21 in combination with FOXM1 regulated the stability and ubiquitination of FOXM1. However, FOXM1 reversed the effects of USP21 knockdown on the radio-resistance of CC cells. Furthermore, FOXM1 knockdown activated the Hippo pathway by inhibiting the nuclear translocation of Yes-associated protein 1 (YAP1), and FOXM1 knockdown attenuated the radio-resistance of CC cells via inhibiting the Hippo-YAP1 pathway. USP21 activated the Hippo pathway by mediating FOXM1. Knockdown of USP21 enhanced the radio-sensitivity of CC cells in vivo. In summary, USP21 contributed to the radio-resistance of CC cells via FOXM1/Hippo signaling, and may serve as a promising target for radio-sensitizers in the radiotherapy of CC.

SPRY4-AS1, A Novel Enhancer RNA, Is a Potential Novel Prognostic Biomarker and Therapeutic Target for Hepatocellular Carcinoma

A growing number of evidence have demonstrated the involvement of enhancer RNAs (eRNAs) in tumor progression. However, the possible functions of eRNAs in hepatocellular carcinoma (HCC) remain largely unclear. Our present research aimed to screen critical eRNAs and to further delve into the clinical significance of eRNAs in HCC patients. In this study, we identified 124 prognosis-related eRNAs by analyzing The Cancer Genome Atlas (TCGA) datasets. Among them, SPRY4 antisense RNA 1 (SPRY4-AS1) may be a key eRNA involved in HCC progression. SPRY4 was a regulatory target of SPRY4-AS1. High SPRY4-AS1 expression was associated with poor prognosis of HCC patients. Kyoto Encyclopedia of Genes and Genomes (KEGG) assays revealed that the mainly enriched biological process included Human papillomavirus infection, Hippo signaling pathway, and Proteoglycans in cancer. Besides, RT-PCR and immunohistochemical staining confirmed SPRY4-AS1 as an overexpressed eRNA in HCC specimens. The pan-cancer assays revealed that SPRY4-AS1 was associated with glioblastoma multiforme (GBM), adrenocortical carcinoma (ACC), brain lower grade glioma (LGG) and mesothelioma(MESO). Positive associations were observed between SPRY4-AS1 and SPRY4 (its target gene) in 16 tumor types. Collectively, our findings reveal a novel eRNA SPRY4-AS1 for HCC progression and suggest that SPRY4-AS1 may be a potential biomarker and therapeutic target for HCC.

The MiR-320 Family Is Strongly Downregulated in Patients with COVID-19 Induced Severe Respiratory Failure

A high incidence of thromboembolic events associated with high mortality has been reported in severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infections with respiratory failure. The present study characterized post-transcriptional gene regulation by global microRNA (miRNA) expression in relation to activated coagulation and inflammation in 21 critically ill SARS-CoV-2 patients. The cohort consisted of patients with moderate respiratory failure (n = 11) and severe respiratory failure (n = 10) at an acute stage (day 0-3) and in the later course of the disease (>7 days). All patients needed supplemental oxygen and severe patients were defined by the requirement of positive pressure ventilation (intubation). Levels of D-dimers, activated partial thromboplastin time (aPTT), C-reactive protein (CRP), and interleukin (IL)-6 were significantly higher in patients with severe compared with moderate respiratory failure. Concurrently, next generation sequencing (NGS) analysis demonstrated increased dysregulation of miRNA expression with progression of disease severity connected to extreme downregulation of miR-320a, miR-320b and miR-320c. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed involvement in the Hippo signaling pathway, the transforming growth factor (TGF)-β signaling pathway and in the regulation of adherens junctions. The expression of all miR-320 family members was significantly correlated with CRP, IL-6, and D-dimer levels. In conclusion, our analysis underlines the importance of thromboembolic processes in patients with respiratory failure and emphasizes miRNA-320s as potential biomarkers for severe progressive SARS-CoV-2 infection.

Hot Spot Analysis of YAP-TEAD Protein-Protein Interaction Using the Fragment Molecular Orbital Method and Its Application for Inhibitor Discovery

The Hippo pathway is an important signaling pathway modulating growth control and cancer cell proliferation. Dysregulation of the Hippo pathway is a common feature of several types of cancer cells. The modulation of the interaction between yes-associated protein (YAP) and transcriptional enhancer associated domain (TEAD) in the Hippo pathway is considered an attractive target for cancer therapeutic development, although the inhibition of PPI is a challenging task. In order to investigate the hot spots of the YAP and TEAD1 interacting complex, an ab initio Fragment Molecular Orbital (FMO) method was introduced. With the hot spots, pharmacophores for the inhibitor design were constructed, then virtual screening was performed to an in-house library. Next, we performed molecular docking simulations and FMO calculations for screening results to study the binding modes and affinities between PPI inhibitors and TEAD1. As a result of the virtual screening, three compounds were selected as virtual hit compounds. In order to confirm their biological activities, cellular (luciferase activity, proximity ligation assay and wound healing assay in A375 cells, qRT-PCR in HEK 293T cells) and biophysical assays (surface plasmon resonance assays) were performed. Based on the findings of the study, we propose a novel PPI inhibitor BY03 and demonstrate a profitable strategy to analyze YAP-TEAD PPI and discover novel PPI inhibitors.