Roles of the Hippo pathway in lung development and tumorigenesis

YAP/TAZ axis was involved in the effects of metformin on breast cancer

Breast cancer is malignant tumours in women. A large amount of data analysis shows that Metformin has been shown to play a significance role in reducing the risk of breast cancer, but the mechanism remains unclear. The hippo signalling pathway can be involved in the formation, metastasis and recurrence of breast cancer. When YAP/TAZ is activated, cells can overcome contact inhibition and enter a state of uncontrolled proliferation. Therefore, YAP/TAZ is considered a potential therapeutic target for breast cancer. Eighty breast cancer patients, forty cases of triple-negative and forty cases of HER-2+, were included in this study. In vitro and in vivo experiments were used to confirm the YAP/TAZ axis was involved in the effects of metformin on breast cancer. EMT plays an important role in breast cancer, including chemoresistance and tumour metastasis. Our results confirmed that YAP could modulate the activity of EMT, which in turn altered tumour resistance. Therefore, MET can inhibit EMT by reducing the expression of YAP, and finally achieve the therapeutic effect of breast cancer. Our findings support metformin as a novel YAP inhibitor and potentially as a novel breast cancer drug.

Targeting Hippo signaling in cancer: novel perspectives and therapeutic potential

As highly conserved among diverse species, Hippo signaling pathway regulates various biological processes, including development, cell proliferation, stem cell function, tissue regeneration, homeostasis, and organ size. Studies in the last two decades have provided a good framework for how these fundamental functions of Hippo signaling are tightly regulated by a network with numerous intracellular and extracellular factors. The Hippo signaling pathway, when dysregulated, may lead to a wide variety of diseases, especially cancer. There is growing evidence demonstrating that dysregulated Hippo signaling is closely associated with tumorigenesis, cancer cell invasion, and migration, as well as drug resistance. Therefore, the Hippo pathway is considered an appealing therapeutic target for the treatment of cancer. Promising novel agents targeting the Hippo signaling pathway for cancers have recently emerged. These novel agents have shown antitumor activity in multiple cancer models and demonstrated therapeutic potential for cancer treatment. However, the detailed molecular basis of the Hippo signaling-driven tumor biology remains undefined. Our review summarizes current advances in understanding the mechanisms by which Hippo signaling drives tumorigenesis and confers drug resistance. We also propose strategies for future preclinical and clinical development to target this pathway.

New insights into the important roles of phase seperation in the targeted therapy of lung cancer

Lung cancer is a complex and heterogeneous disease characterized by abnormal growth and proliferation of lung cells. It is the leading cause of cancer-related deaths worldwide, accounting for approximately 18% of all cancer deaths. In recent years, targeted therapy has emerged as a promising approach to treat lung cancer, which involves the use of drugs that selectively target specific molecules or signaling pathways that are critical for the growth and survival of cancer cells. Liquid-liquid phase separation (LLPS) is a fundamental biological process that occurs when proteins and other biomolecules separate into distinct liquid phases in cells. LLPS is essential for various cellular functions, including the formation of membraneless organelles, the regulation of gene expression, and the response to stress and other stimuli. Recent studies have shown that LLPS plays a crucial role in targeted therapy of lung cancer, including the sequestration of oncogenic proteins and the development of LLPS-based drug delivery systems. Understanding the mechanisms of LLPS in these processes could provide insights into new therapeutic strategies to overcome drug resistance in lung cancer cells.

Identification of ALG3 as a potential prognostic biomarker in lung adenocarcinoma

Background

The abnormal expression of Alpha-1,3-mannosyltransferase (ALG3) has been implicated in tumor promotion. However, the clinical significance of ALG3 in Lung Adenocarcinoma (LUAD) remains poorly understood. Therefore, we aimed to assess the prognostic value of ALG3 and its association with immune infiltrates in LUAD.

Methods

The transcriptional expression profiles of ALG3 were obtained from the Cancer Genome Atlas (TCGA), comparing lung adenocarcinoma tissue with normal tissues. To determine the prognostic significance of AGL3, Kaplan-Meier plotter, and Cox regression analysis were employed. Logistic regression was utilized to analyze the association between ALG3 expression and clinical characteristics. Additionally, a receiver operating characteristic (ROC) curve and a nomogram were constructed. To explore the underlying mechanisms, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and gene set enrichment analysis (GSEA) was conducted. The relationship between AGL3A mRNA expression and immune infiltrates was investigated using the tumor immune estimation resource (TIMER) and tumor-immune system interaction database (TISIDB). Furthermore, an in vitro experiment was performed to assess the impact of ALG3 mRNA on lung cancer stemness abilities and examine key signaling pathway proteins.

Results

Our results revealed the ALG3 mRNA and protein expression in patients with LUAD was much higher than that in adjacent normal tissues. High expression of ALG3 was significantly associated with N stage (N0, HR = 1.98, P = 0.002), pathological stage (stage I, HR = 2.09, P = 0.003), and the number of pack years (<40, HR = 2.58, P = 0.001). Kaplan-Meier survival analysis showed that high expression of ALG3 was associated with poor overall survival (P < 0.001), disease-free survival (P < 0.001), and progression-free interval (P = 0.007). Through multivariate analysis, it was determined that elevated ALG3 expression independently impacted overall survival (HR = 1.325, P = 0.04). The Tumor Immune Estimation Resource discovered a link between ALG3 expression and tumor-infiltrating immune cells in LUAD. Additionally, ROC analysis proved that ALG3 is a reliable diagnostic marker for LUAD (AUC:0.923). Functional pathways analysis identified that ALG3 is negatively correlated with FAT4. We performed qRT-PCR to assess that knockdown ALG3 expression significantly upregulated FAT4 expression. Spheroid assay and flow cytometry analysis results showed that downregulated of ALG3 inhibited H1975 cell line stemness. Western blot analysis revealed that decreased ALG3 inhibited the YAP/TAZ signal pathway.

Conclusion

High expression of ALG3 is strongly associated with poor prognosis and immune infiltrates in LUAD.

A derivant of ginsenoside CK and its inhibitory effect on hepatocellular carcinoma

Epidemiological studies have shown that hepatocellular carcinoma (HCC) is a main cause of tumor death worldwide. Accumulating data indicate that ginsenoside CK is an effective compound for preventing HCC growth and development. However, improvement of pharmaceutical effect of the ginsenoside CK is still needed. In our study, we performed acetylation of ginsenoside CK (CK-3) and investigated the antitumor effects of the derivative in vitro and in vivo. The cytotoxicity analysis revealed that compared with CK, CK-3 could inhibit the proliferation of multiple tumor cell lines at a lower concentration. Treating with CK-3 on HCC cells arrested cell cycle in G2/M phase and induced cell apoptosis through AO/EB staining, TUNEL analysis and flow cytometry. Meanwhile, CK-3 significantly inhibited tumor growth in an HCC xenograft model and showed no side effect on the function of the main organs. Mechanistically, whole transcriptome analysis revealed that the antitumor effect of CK-3 was involved in the Hippo signaling pathway. The immunoblotting and immunofluorescence results illustrated that CK-3 directly facilitated the phosphorylation of YAP1 and decreased the expression of the main transcription factor TEAD2 in HCC cell lines and tumor tissue sections. Collectively, our results demostrate the formation of a new derivative of ginsenoside CK and its regulatory mechanism in HCC, which could activate the Hippo-YAP1-TEAD2 signaling pathway to regulate HCC progression. This research could provide a new direction for traditional Chinese medicine in the therapy of tumors.

Yes-associated protein is dysregulated during nitrofen-induced hypoplastic lung development due to congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a birth defect associated with abnormal lung development. Yes-associated protein (YAP) is a core kinase of the Hippo pathway, which controls organ size during development. The absence of YAP protein during lung development results in hypoplastic lungs comparable to the lung phenotype in CDH (Mahoney, Dev Cell 30(2):137-150, 2014). We aimed to describe the expression of YAP during normal and nitrofen-induced abnormal lung development.

METHODS

Intra-gastric administration of dams with 100 mg of nitrofen was used to induce CDH and abnormal lung development in the embryos. Immunofluorescence was performed to visualize the localization of YAP and p-YAP during lung development (E15, E18, E21). Western Blotting was used to determine the abundance of YAP and p-YAP in E21 control and nitrofen-induced hypoplastic CDH lungs.

RESULTS

Immunofluorescence demonstrated cytoplasmic localization of YAP protein in airway epithelial and mesenchymal cells of nitrofen-induced hypoplastic lungs compared to nuclear localization in control lungs. Western Blotting showed a decrease (p = 0.0188) in abundance of YAP (active form) and increase in p-YAP (inactive form) in hypoplastic lungs compared to control lungs.

CONCLUSION

Our results demonstrate that YAP protein is mostly phosphorylated, inactive, and expressed in the cytoplasm at the later stages of nitrofen-induced hypoplastic lung development indicating that the alteration in regulation of YAP can be associated with the pathogenesis of abnormal lung development in experimental CDH.

The Hippo Signaling Core Components YAP and TAZ as New Prognostic Factors in Lung Cancer

Background

The Hippo pathway is an essential signaling cascade that regulates cell and organ growth. However, there is no consensus about (i) the expression levels of the Hippo signaling core components yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) in lung cancer, especially in small cell lung cancer (SCLC), or (ii) their association with the prognosis of patients with SCLC.

Methods

We screened relevant articles and identified eligible studies in the PubMed, EMBASE, COCHRANE, and WanFang databases. A combined analysis was performed to investigate (i) the expression levels of the major effectors, YAP and TAZ, in lung cancer and its subsets and (ii) their prognostic role in lung cancer, especially in SCLC.

Results

In total, 6 studies related to TAZ and 13 studies concerning YAP were enrolled in this meta-analysis. We found that high TAZ expression was significantly associated with poor overall survival (OS) of patients with non-small cell lung cancer (NSCLC) in the overall population [Ph &lt; 0.001, crude hazard ratio (HR) = 1.629, 95% CI = 1.199–2.214 for TAZ expression; Ph = 0.029, adjusted HR = 2.127, 95% CI = 1.307–3.460 for TAZ], the Caucasian population (Ph = 0.043, crude HR = 1.233, 95% CI = 1.030–1.477 for TAZ expression), and the Asian population (Ph = 0.551, adjusted HR = 2.676, 95% CI = 1.798–3.982 for TAZ). Moreover, there was a significant negative association between YAP expression and an unsatisfactory survival of patients with lung cancer (Ph = 0.327, crude HR = 1.652, 95% CI = 1.211–2.253 for YAP expression) and patients with NSCLC [disease-free survival (DFS): Ph = 0.693, crude HR = 2.562, 95% CI = 1.876–3.499 for YAP expression; Ph = 0.920, crude HR = 2.617, 95% CI = 1.690–4.052 for YAP-mRNA; OS: Ph = 0.878, crude HR = 1.777, 95% CI = 1.233–2.562 for YAP expression], especially in the Asian population (DFS: Ph = 0.414, crude HR = 2.515, 95% CI = 1.755–3.063; OS: Ph = 0.712, crude HR = 1.772, 95% CI = 1.214–2.587). However, no association was observed in the multivariate combined analysis. High YAP expression was significantly associated with short OS of patients with SCLC in our combined multivariate analysis in the Asian population (Ph = 0.289, crude HR = 4.482, 95% CI = 2.182–9.209), but not with crude data (Ph = 0.033, crude HR = 1.654, 95% CI = 0.434–6.300).

Conclusion

The Hippo pathway is involved in carcinogenesis and progression of NSCLC and SCLC, and high expression levels of YAP and TAZ are independent and novel prognostic factors for lung cancer.

Restraint of chaperonin containing T-complex protein-1 subunit 3 has antitumor roles in non-small cell lung cancer via affection of YAP1

The implication of chaperonin containing T-complex protein-1 subunit 3 (CCT3) in carcinogenesis has been observed in a diverse malignancies. However, the relevance of CCT3 in non-small cell lung cancer (NSCLC) has not been well addressed. This research is dedicated to investigating the expression pattern and functional role of CCT3 in NSCLC. An elevation in CCT3 levels was observed in NSCLC tissue, which was linked to a reduced overall survival rate. The inhibition of CCT3 by shRNA-mediated gene silencing induced suppressive effects on the transformative phenotypes of NSCLC cells, including the inhibition of cell proliferation and invasion, and the induction of cell cycle arrest and apoptosis. Further investigation revealed that the silencing of CCT3 led to the suppression of Yes-associated protein 1 (YAP1), and decreased the expression of YAP1 target genes in NSCLC cells. The activation of YAP1 via forced expression of constitutively active YAP1 mutant reversed CCT3-restraint-evoked antitumor effects in NSCLC cells. Crucially, NSCLC cells with CCT3 silencing also exhibited weakened oncogenicity in nude mice associated with the down-regulation of YAP1 activation in xenografts. To sum up, these observations of our work show that the inhibition of CCT3 produces antitumor effects in NSCLC via the suppression of YAP1. This study unveils a possible role CCT3/YAP1 axis in NSCLC and suggests CCT3 as a candidate anticancer target.

Developmental Pathways Underlying Lung Development and Congenital Lung Disorders

Lung organogenesis is a highly coordinated process governed by a network of conserved signaling pathways that ultimately control patterning, growth, and differentiation. This rigorously regulated developmental process culminates with the formation of a fully functional organ. Conversely, failure to correctly regulate this intricate series of events results in severe abnormalities that may compromise postnatal survival or affect/disrupt lung function through early life and adulthood. Conditions like congenital pulmonary airway malformation, bronchopulmonary sequestration, bronchogenic cysts, and congenital diaphragmatic hernia display unique forms of lung abnormalities. The etiology of these disorders is not yet completely understood; however, specific developmental pathways have already been reported as deregulated. In this sense, this review focuses on the molecular mechanisms that contribute to normal/abnormal lung growth and development and their impact on postnatal survival.

The novel FAT4 activator jujuboside A suppresses NSCLC tumorigenesis by activating HIPPO signaling and inhibiting YAP nuclear translocation

FAT atypical cadherin 4 (FAT4) has been identified as a tumor suppressor in lung cancers. However, no agent for lung cancer treatment targeting FAT4 has been used in the clinic. Jujuboside A (JUA) is a major active compound in Semen Ziziphi Spinosae. Semen Ziziphi Spinosae is a traditional Chinese herbal medicine used clinically for tumor treatment to improve patients' quality of life. However, the anti-lung cancer activity and the underlying mechanisms of JUA are not yet fully understood. Here, we demonstrated the anti-lung cancer activity of JUA in two lung cancer mice models and three non-small cell lung cancer (NSCLC) cell lines, and further illustrated its underlying mechanisms. JUA suppressed the occurrence and development of lung cancer and extended mice survival in vivo, and suppressed NSCLC cell activities through cell cycle arrest, proliferation suppression, stemness inhibition and senescence promotion. Moreover, JUA directly bound with and activated FAT4, subsequently activating FAT4-HIPPO signaling and inhibiting YAP nuclear translocation. Knockdown of FAT4 diminished JUA's effects on HIPPO signaling, YAP nuclear translocation, cell proliferation and cellular senescence. In conclusion, JUA significantly suppressed NSCLC tumorigenesis by regulating FAT4-HIPPO-YAP signaling. Our findings suggest that JUA is a novel FAT4 activator that can be developed as a promising NSCLC therapeutic agent targeting the FAT4-HIPPO-YAP pathway.

Hippo pathway: Regulation, deregulation and potential therapeutic targets in cancer

Hippo pathway is a master regulator of development, cell proliferation, stem cell function, tissue regeneration, homeostasis, and organ size control. Hippo pathway relays signals from different extracellular and intracellular events to regulate cell behavior and functions. Hippo pathway is conserved from Protista to eukaryotes. Deregulation of the Hippo pathway is associated with numerous cancers. Alteration of the Hippo pathway results in cell invasion, migration, disease progression, and therapy resistance in cancers. However, the function of the various components of the mammalian Hippo pathway is yet to be elucidated in detail especially concerning tumor biology. In the present review, we focused on the Hippo pathway in different model organisms, its regulation and deregulation, and possible therapeutic targets for cancer treatment.

Using Biosensors to Study Protein-Protein Interaction in the Hippo Pathway

The Hippo signaling network is dependent on protein–protein interactions (PPIs) as a mechanism of signal transduction to regulate organ size, cellular proliferation and differentiation, tumorigenesis, and other cellular processes. Current efforts aim to resolve the complex regulation of upstream Hippo components or focus on identifying targeted drugs for use in cancer therapy. Despite extensive characterization of the Hippo pathway interactome by affinity purification mass spectrometry (AP-MS) and other methodologies, previous research methods have not been sufficient to achieve these aims. In this review, we describe several recent studies that make use of luciferase-based biosensors as a new approach to study the Hippo Pathway. These biosensors serve as powerful tools with which to study PPIs both in vitro using purified biosensor proteins, and in real time in live cells. Notably, luciferase biosensors have excellent sensitivity and have been used to screen for upstream kinase regulators of the Hippo pathway. Furthermore, the high sensitivity and stability of these biosensors enables their application in high throughput screening for Hippo-targeted chemotherapeutics. Finally, we describe the strengths and weaknesses of this method relative to AP-MS and discuss potential future directions for using biosensors to study Hippo signaling.

ACTL6A promotes the growth in non-small cell lung cancer by regulating Hippo/Yap pathway

Purpose: To delve into the related molecular mechanism of ACTL6A on non-small cell lung cancer (NSCLC) cell growth and apoptosis.Methods: Quantitative real-time polymerase chain reaction, immunohistochemical staining, and western blot assays were employed to examine ACTL6A mRNA and protein expression in four NSCLC cell line (NCI-H2170, LTEP-s, NCI-H1703, and PC-9) and normal lung cell line (BEAS-2B). CCK-8 cell viability assays and clone formation assay were applied to verify the cell proliferation of NCI-H2170 cell line after knockdown of ACTL6A. Flow cytometry assays were applied to check the role of ACTL6A in the apoptosis of NSCLC cells. The western blot assays were employed to examine the protein expression of WWC1, YAP, TAZ, and CYR61 in NCI-H2170 after knockdown of ACTL6A. Finally, xenograft tumor was taken out and checked the tumor volumes and weight. Immunohistochemical staining and western blot assays were employed to examine cell proliferation and apoptosis of NSCLC in vivo.Results: In this study, the results showed that the mRNA and protein expression level of ACTL6A was higher in four NSCLC cell line than normal lung cell line, respectively. Suppression of ACTL6A inhibited the growth and promoted apoptosis of NSCLC cells. Meanwhile, ACTL6A promotes tumor growth and inhibits apoptosis of NSCLC in vivo via Hippo/YAP signaling pathway.Conclusion: ACTL6A promotes the proliferation in NSCLC by regulating Hippo/YAP pathway.

Cytoskeletal Organization Correlates to Motility and Invasiveness of Malignant Mesothelioma Cells

Simple Summary

The cytoskeleton is responsible for maintaining normal tissue homeostasis by a tight regulation of cell morphogenesis and cell migration. This homeostasis is lost in cancer mainly because alterations in cytoskeletal dynamics are leading to an increased migratory and invasive capacity of cancer cells. The organization of the cytoskeleton is by large an unknown factor in malignant mesothelioma; therefore we sought to examine the cytoskeletal dynamics and invasive properties of different malignant mesothelioma cell lines originating from patients. Our data suggest that it is possible to classify malignant mesothelioma cell lines into separate categories using straight forward cell staining and analysis of the morphological and invasive capacity of mesothelioma cells. Early diagnosis and new diagnostic tools are urgently needed to effectively treat patients and we propose that the analyses described in this article could potentially provide diagnostic tools that can be further tested on patients.

Abstract

Malignant mesothelioma (MM) is a rare but highly aggressive cancer that primarily originates from the pleura, peritoneum or pericardium. There is a well-established link between asbestos exposure and progression of MM. Direct invasion of the surrounding tissues is the main feature of MM, which is dependent on dysregulated communication between the mesothelium and the microenvironment. This communication is dependent on the dynamic organization of the cytoskeleton. We have analyzed the organization and function of key cytoskeletal components in MM cell lines of increasing malignancies measured as migratory and invasive properties, and we show that highly malignant and invasive MM cells have an organization of the actin filament and vimentin systems that is distinct from the less malignant MM cell lines. In addition, the Hippo tumor suppressor pathway was inactivated in the invasive MM cells, which was seen as increased YAP nuclear localization.

A comprehensive enhancer screen identifies TRAM2 as a key and novel mediator of YAP oncogenesis

BACKGROUND

Frequent activation of the co-transcriptional factor YAP is observed in a large number of solid tumors. Activated YAP associates with enhancer loci via TEAD4-DNA-binding protein and stimulates cancer aggressiveness. Although thousands of YAP/TEAD4 binding-sites are annotated, their functional importance is unknown. Here, we aim at further identification of enhancer elements that are required for YAP functions.

RESULTS

We first apply genome-wide ChIP profiling of YAP to systematically identify enhancers that are bound by YAP/TEAD4. Next, we implement a genetic approach to uncover functions of YAP/TEAD4-associated enhancers, demonstrate its robustness, and use it to reveal a network of enhancers required for YAP-mediated proliferation. We focus on EnhancerTRAM2, as its target gene TRAM2 shows the strongest expression-correlation with YAP activity in nearly all tumor types. Interestingly, TRAM2 phenocopies the YAP-induced cell proliferation, migration, and invasion phenotypes and correlates with poor patient survival. Mechanistically, we identify FSTL-1 as a major direct client of TRAM2 that is involved in these phenotypes. Thus, TRAM2 is a key novel mediator of YAP-induced oncogenic proliferation and cellular invasiveness.

CONCLUSIONS

YAP is a transcription co-factor that binds to thousands of enhancer loci and stimulates tumor aggressiveness. Using unbiased functional approaches, we dissect YAP enhancer network and characterize TRAM2 as a novel mediator of cellular proliferation, migration, and invasion. Our findings elucidate how YAP induces cancer aggressiveness and may assist diagnosis of cancer metastasis.

Inhibitors of cytoskeletal dynamics in malignant mesothelioma

Malignant mesotheliomas (MMs) are highly aggressive mesenchymal tumors that originate from mesothelial cells lining serosal cavities; i.e., the pleura, peritoneum, and pericardium. Classically, there is a well-established link between asbestos exposure, oxidative stress, release of reactive oxygen species, and chronic inflammatory mediators that leads to progression of MMs. MMs have an intermediate phenotype, with co-expression of mesenchymal and epithelial markers and dysregulated communication between the mesothelium and the microenvironment. We have previously shown that the organization and function of key cytoskeletal components can distinguish highly invasive cell lines from those more indolent. Here, we used these tools to study three different types of small-molecule inhibitors, where their common feature is their influence on production of reactive oxygen species. One of these, imipramine blue, was particularly effective in counteracting some key malignant properties of highly invasive MM cells. This opens a new possibility for targeted inhibition of MMs based on well-established molecular mechanisms.

Regulatory role of microRNAs in cancer through Hippo signaling pathway

Cancer is the major cause of death worldwide in countries of all income levels. The Hippo signaling pathway is a Drosophila kinase gene that was identified to regulate organ size, cell regeneration, and contribute to tumorigenesis. A huge variety of extrinsic and intrinsic signals regulate the Hippo signaling pathway. The Hippo signaling pathway consists of a wide array of components that merge numerous signals such as mechanical signals to address apoptosis resistance, cell proliferation, cellular outputs of growth, cell death and survival at cellular and tissue level. Recent studies have shed new light on the regulatory role of microRNAs in Hippo signaling and how they contribute to cancer progression. MicroRNAs influence various cancer-related processes such as, apoptosis, proliferation, migration, cell cycle and metabolism. Inhibition and overexpression of miRNAs via miRNA mimics and miRNA inhibitors, respectively, can uncover a hopeful and reliable insight for treatment and early diagnosis of cancer patients. In this review we will discuss our current understanding of regulatory role of miRNAs in Hippo signaling pathway.

Up-regulated acylglycerol kinase (AGK) expression associates with gastric cancer progression through the formation of a novel YAP1-AGK-positive loop

Acylglycerol kinase (AGK) uses adenosine triphosphate (ATP) and acylglycerol to generate adenosine diphosphate (ADP) and acyl‐sn‐glycerol 3‐phosphate in cells. Recent evidence has demonstrated that dysregulated AGK expression is associated with the development of various human cancers. This study investigated the effects of AGK on gastric cancer cell proliferation and carcinogenesis and explored the underlying molecular events. AGK expression was up‐regulated in gastric cancer and was associated with poor prognosis in gastric cancer patients. AGK overexpression increased gastric cancer proliferation, invasion capacity and the expression of the epithelial‐mesenchymal transition markers in vitro. Conversely, the knockdown of AGK expression reduced gastric cancer cell proliferation in vitro and in nude mouse tumour cell xenografts. Importantly, AGK expression was associated with the YAP1 expression in gastric cancer cells and tissues. YAP1 expression also transcriptionally induced AGK expression through the binding of TEAD to the AGK gene promoter. However, AGK expression inhibited the activation of the Hippo pathway proteins and induced YAP1 nuclear localization to enhance the transcription activity of YAP1/TEADs. In conclusion, the study demonstrates that AGK is not only a novel target of the Hippo‐YAP1 pathway, but that it also positively regulates YAP1 expression, thus forming a YAP1‐AGK–positive feedback loop.

The crosstalk between lncRNAs and the Hippo signalling pathway in cancer progression

LncRNAs play a pivotal role in the regulation of epigenetic modification, cell cycle, differentiation, proliferation, migration and other physiological activities. In particular, considerable studies have shown that the aberrant expression and dysregulation of lncRNAs are widely implicated in cancer initiation and progression by acting as tumour promoters or suppressors. Hippo signalling pathway has attracted researchers’ attention as one of the critical cancer‐related pathways in recent years. Increasing evidences have demonstrated that lncRNAs could interact with Hippo cascade and thereby contribute to acquisition of multiple malignant hallmarks, including proliferation, metastasis, relapse and resistance to anti‐cancer treatment. Specifically, Hippo signalling pathway is reported to modulate or be regulated by widespread lncRNAs. Intriguingly, certain lncRNAs could form a reciprocal feedback loop with Hippo signalling. More speculatively, lncRNAs related to Hippo pathway have been poised to become important putative biomarkers and therapeutic targets in human cancers. Herein, this review focuses on the crosstalk between lncRNAs and Hippo pathway in carcinogenesis, summarizes the comprehensive role of Hippo‐related lncRNAs in tumour progression and depicts their clinical diagnostic, prognostic or therapeutic potentials in tumours.

MicroRNA-188 inhibits biological activity of lung cancer stem cells through targeting MDK and mediating the Hippo pathway

New Findings

What is the central question of this study?

The aim was to investigate the function of microRNA‐188 in the biological characteristics of lung cancer stem cells and the molecular mechanisms involved.

What is the main finding and its importance?

This study highlights a new molecular mechanism involving microRNA‐188, MDK and the Hippo signalling pathway that plays a suppressive role in biological activity of lung cancer stem cells. This finding might offer new insights into gene‐based therapy for lung cancer.

Abstract

MicroRNAs (miRNAs) have been implicated in lung cancer and reported as new promising diagnostic and therapeutic tools for cancer control. Here, we investigated the action of microRNA‐188 (miR‐188) in lung cancer stem cells. We first tested miR‐188 expression in clinical samples of lung cancer patients, and a low expression profile of miR‐188 was found. Next, we analysed the role of miR‐188 in lung cancer stem cells with cell growth assays. To verify the in vitro results, we used a xenograft model to validate the capability of miR‐188 in tumorigenesis. Overexpression of miR‐188 reduced viability and metastasis of cancer stem cells. Similar results were reproduced in vivo, where overexpression of miR‐188 retarded tumour growth in mice. We also identified MDK as a target of miR‐188, and overexpression of MDK was found in lung cancer samples. Overexpressed MDK promoted the malignant behaviours of lung cancer stem cells. In addition, the Hippo pathway was found to be inactivated in lung cancer tissues, presenting as increased levels of YAP and TAZ. Suppression of the Hippo pathway also enhanced lung cancer stem cell activity and promoted the growth of xenograft tumours. To sum up, our results reveal that miR‐188 inhibits the malignant behaviours of lung cancer stem cells and the growth of xenograft tumours. This study might offer new insights into gene‐based therapies for cancer.

Sophoridine inhibits lung cancer cell growth and enhances cisplatin sensitivity through activation of the p53 and Hippo signaling pathways

BACKGROUND

Sophoridine, a quinolizidine alkaloid extracted from the Chinese herb Sophora alopecuroides L., has been reported to exert antitumor effects against multiple human cancers. However, few studies have evaluated its tumor-suppressing effects and associated mechanism with respect to lung cancer, in addition to its potential to be used for clinical lung cancer treatment.

METHODS

Different types of lung cancer cells were used to investigate the antitumor effects of sophoridine using cell viability, colony formation, and cell invasion, and migration assays. To determine the signaling pathways involved, western blot analysis, quantitative real-time polymerase chain reaction, an in vivo ubiquitination assay, and immunohistochemistry were used in cellular assays and with a subcutaneous xenograft model in BALB/c mice.

RESULTS

Sophoridine significantly suppressed the proliferation of and colony formation by lung cancer cells in vitro. Transwell assays demonstrated that sophoridine also inhibited invasion and migration in lung cancer cells. In addition, sophoridine enhanced the effects of cisplatin on lung cancer cells. A mechanistic study revealed that sophoridine significantly activated the Hippo and p53 signaling pathways, and mouse xenograft experiments further confirmed in vitro findings in lung cancer cells.

CONCLUSIONS

Taken together, these results suggest that sophoridine can inhibit lung cancer progression and enhance the effects of the anticancer drug cisplatin against lung cancer cells. The mechanism of action of sophoridine might involve the Hippo and p53 signaling pathways.

Retinoic Acid: A Key Regulator of Lung Development

Retinoic acid (RA) is a key molecular player in embryogenesis and adult tissue homeostasis. In embryo development, RA plays a crucial role in the formation of different organ systems, namely, the respiratory system. During lung development, there is a spatiotemporal regulation of RA levels that assures the formation of a fully functional organ. RA signaling influences lung specification, branching morphogenesis, and alveolarization by regulating the expression of particular target genes. Moreover, cooperation with other developmental pathways is essential to shape lung organogenesis. This review focuses on the events regulated by retinoic acid during lung developmental phases and pulmonary vascular development; also, it aims to provide a snapshot of RA interplay with other well-known regulators of lung development.

Mst1/2 kinases restrain transformation in a novel transgenic model of Ras driven non-small cell lung cancer

Non-small cell lung cancer remains a highly lethal malignancy. Using the tamoxifen inducible Hnf1b:CreERT2 (H) transgenic mouse crossed to the LsL-KrasG12D (K) transgenic mouse, we recently discovered that an Hnf1b positive cell type in the lung is sensitive to adenoma formation when expressing a mutant KrasG12D allele. In these mice, we observe adenoma formation over a time frame of three to six months. To study specificity of the inducible Hnf1b:CreERT2 in the lung, we employed lineage tracing using an mTmG (G) reporter allele. This technique revealed recombined, GFP+ cells were predominantly SPC+. We further employed this technique in HKG mice to determine Hnf1b+ cells give rise to adenomas that express SPC and TTF1. Review of murine lung tissue confirmed a diagnosis of adenoma and early adenocarcinoma, a pathologic subtype of non-small cell lung cancer. Our expanded mouse model revealed loss of Mst1/2 promotes aggressive lung adenocarcinoma and large-scale proteomic analysis revealed upregulation of PKM2 in the lungs of mice with genetic deletion of Mst1/2. PKM2 is a known metabolic regulator in proliferating cells and cancer. Using a human lung adenocarcinoma cell line, we show pharmacologic inhibition of Mst1/2 increases the abundance of PKM2, indicating genetic loss or pharmacologic inhibition of Mst1/2 directly modulates the abundance of PKM2. In conclusion, here we report a novel model of non-small cell lung cancer driven by a mutation in Kras and deletion of Mst1/2 kinases. Tumor development is restricted to a subset of alveolar type II cells expressing Hnf1b. Our data show loss of Mst1/2 regulates levels of a potent metabolic regulator, PKM2.

MicroRNA Profiling in Wilms Tumor: Identification of Potential Biomarkers

Wilms tumor (WT) is the most frequently diagnosed malignant renal tumor in children. With current treatments, ~90% of children diagnosed with WT survive and generally present with tumors characterized by favorable histology (FHWT), whereas prognosis is poor for the remaining 10% of cases where the tumors are characterized by cellular diffuse anaplasia (DAWT). Relatively few studies have investigated microRNA-related epigenetic regulation and its relationship with altered gene expression in WT. Here, we aim to identify microRNAs differentially expressed in WT and describe their expression in terms of cellular anaplasia, metastasis, and association with the main genetic alterations in WT to identify potential prognostic biomarkers. Expression profiling using TaqMan low-density array was performed in a discovery cohort consisting of four DAWT and eight FHWT samples. Relative quantification resulted in the identification of 109 (48.7%) microRNAs differentially expressed in both WT types. Of these, miR-10a-5p, miR-29a-3p, miR-181a-5p, miR-200b-3p, and miR-218-5p were selected and tested by RT-qPCR on a validation cohort of 53 patient samples. MiR-29a and miR-218 showed significant differences in FHWT with low (P = 0.0018) and high (P = 0.0131) expression, respectively. To discriminate between miRNA expression FHWTs and healthy controls, the receiver operating characteristic (ROC) curves were obtained; miR-29a AUC was 0.7843. Furthermore, low expression levels of miR-29a and miR-200b (P = 0.0027 and P = 0.0248) were observed in metastatic tumors. ROC curves for miR-29a discriminated metastatic patients (AUC = 0.8529) and miR-200b (AUC = 0.7757). To confirm the differences between cases with poor prognosis, we performed in situ hybridization for three microRNAs in five DAWT and 17 FHWT samples, and only significant differences between adjacent tissues and FHWT tumors were found for miR-181a, miR-200b, and miR-218, in both total pixels and nuclear analyses. Analysis of copy number variation in genes showed that the most prevalent alterations were WTX (47%), IGF2 (21%), 1q (36%) gain, 1p36 (16%), and WTX deletion/1q duplicate (26%). The five microRNAs evaluated are involved in the Hippo signaling pathway and participate in Wilms tumor development through their effects on differentiation, proliferation, angiogenesis, and metastasis.

Genetically encoded fluorescent biosensors illuminate kinase signaling in cancer

Protein kinase signaling networks stringently regulate cellular processes, such as proliferation, motility, and cell survival. These networks are also central to the evolution and progression of cancer. Accordingly, genetically encoded fluorescent biosensors capable of directly illuminating the spatiotemporal dynamics of kinase signaling in live cells are being increasingly used to investigate kinase signaling in cancer cells and tumor tissue sections. These biosensors enable visualization of biological processes and events directly in situ, preserving the native biological context and providing detailed insight into their localization and dynamics in cells. Herein, we first review common design strategies for kinase activity biosensors, including signaling targets, biosensor components, and fluorescent proteins involved. Subsequently, we discuss applications of biosensors to study the biology and management of cancer. These versatile molecular tools have been deployed to study oncogenic kinase signaling in living cells and image kinase activities in tumors or to decipher the mechanisms of anticancer drugs. We anticipate that the diversity and precision of genetically encoded biosensors will expand their use to further unravel the dysregulation of kinase signaling in cancer and the modes of actions of cancer-targeting drugs.

Negative regulators of Wnt signaling in non-small cell lung cancer: Theoretical basis and therapeutic potency

Significant advances in the treatment of non-small cell lung cancer (NSCLC) have been made over the past decade, and they predominantly involve molecular targets such as epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements. However, despite the initial good response, drug resistance eventually develops. The Wnt signaling pathway has recently been considered important in embryonic development and tumorigenesis in many cancers, particularly NSCLC. Moreover, the aberrant Wnt pathway plays a significant role in NSCLC and is associated with cancer cell proliferation, metastasis, invasion and drug resistance, and the suppression of canonical or noncanonical Wnt signaling through various biological or pharmacological negative regulators has been proven to produce specific anticancer effects. Thus, blocking the Wnt pathway via its negative regulators may overcome the resistance of current treatment methods and lead to new treatment strategies for NSCLC. Therefore, in this review, we summarize recent studies on the role of negative regulators in Wnt signaling in NSCLC and the therapeutic potency of these molecules as agents and targets for NSCLC treatments.

PDK-1 mediated Hippo-YAP-IRS2 signaling pathway and involved in the apoptosis of non-small cell lung cancer cells

Pyruvate dehydrogenase kinase-1 (PDK-1), a gatekeeper enzyme, was involved in cancer progression, such as tumor angiogenesis, cell survival, and growth. Recent evidence indicated that PDK-1 may be involved in lung cancer, however, the function and underlying mechanism of PDK-1 is remaining unclear. In the present study, our aim was to investigate the role and mechanisms of PDK-1 in human non-small cell lung cancer (NSCLC) cells. We first observed that PDK-1 was highly expressed in NSCLC cell lines. PDK-1 silence resulted in the inhibition of NSCLC cell survival. Also, cell apoptosis and caspase-3 activity were increased by PDK-1 knockdown in H1299 and A549 cells. Attenuation of PDK-1 expression blocked YAP and insulin receptor substrate 2 (IRS2) expression, and PDK-1 silence suppressed IRS2 expression dependent on Hippo-YAP signaling pathway. Moreover, further studies confirmed that YAP or IRS2 overexpression reversed the action of PDK-1 in NSCLC cells. In conclusion, our findings indicate that PDK1/Hippo-YAP/IRS2 signaling pathway plays a critical role in NSCLC cell survival and apoptosis.

Identification of Prolyl isomerase Pin1 as a novel positive regulator of YAP/TAZ in breast cancer cells

The Hippo signalling pathway plays very important roles in tumorigenesis, metastasis, organ size control, and drug resistance. Although, it has been shown that the two major components of Hippo pathway, YAP and TAZ, play very crucial role in tumorigenesis and drug resistance, the exact molecular mechanisms are still unknown. Recently, we have shown that the prolyl isomerase Pin1 regulates the activity of Hippo pathway through interaction with Hippo component LATS kinase. Thus we asked if Pin1 is also able to interact with other Hippo pathway components. Therefore, in order to investigate whether Pin1 can interacts with other components of the Hippo pathway, we performed GST-pull down and co-immunoprecipitation (Co-IP) assays and have identified two Hippo components YAP and TAZ oncoproteins as novel binding partner of Pin1. We found that Pin1 interacts with YAP/TAZ in a phosphorylation-independent manner and WW domain of Pin1 is necessary for this interaction. Moreover, by using real time qRT-PCR, Cycloheximide chase, luciferase reporter, cell viability and soft agar assays, we have shown that Pin1 increases the tumorigenic and drug-resistant activity of YAP/TAZ through stabilization of YAP/TAZ at protein levels. Together, we have identified Pin1 as a novel positive regulator of YAP/TAZ in tumorigenesis and drug resistance of breast cancer cells. These findings will provide a significant contribution for targeting the Pin1-YAP/TAZ signaling for the successful treatment of tumorigenesis and drug resistance of breast and other cancers in the future.

Regenerative therapy based on miRNA-302 mimics for enhancing host recovery from pneumonia caused by Streptococcus pneumoniae

Bacterial pneumonia remains a leading cause of morbidity and mortality worldwide. A defining feature of pneumonia is lung injury, leading to protracted suffering and vulnerability long after bacterial clearance. Little is known about which cells are damaged during bacterial pneumonia and if the regenerative process can be harnessed to promote tissue repair and host recovery. Here, we show that infection of mice with Streptococcus pneumoniae (Sp) caused substantial damage to alveolar epithelial cells (AEC), followed by a slow process of regeneration. Concurrent with AEC regeneration, the expression of miRNA-302 is elevated in AEC. Treatment of Sp-infected mice with miRNA-302 mimics improved lung functions, host recovery, and survival. miRNA-302 mediated its therapeutic effects, not by inhibiting apoptosis and preventing damage, but by promoting proliferation of local epithelial progenitor cells to regenerate AEC. These results demonstrate the ability of microRNA-based therapy to promote AEC regeneration and enhance host recovery from bacterial pneumonia.

The Hippo signaling effector WWTR1 is a metastatic biomarker of gastric cardia adenocarcinoma

Background

Gastric cardia adenocarcinoma (GCA) is an aggressive subtype of gastric cancer with a high metastatic rate. However, the metastatic biomarker of GCA has not been established.

Methods

To search for the biomarker for GCA metastasis, we here examined expression of the Hippo signaling effector WWTR1 (WW domain containing transcription regulator 1, commonly listed as TAZ) in tumor tissue samples from 214 GCA cases using the tissue microarray assay (TMA), and statistically analyzed association of the WWTR1 expression with metastasis-related pathological outcomes and cumulative survival of the GCA patients. Furthermore, shRNA knockdown was used to determine the role of WWTR1 in promoting cell migration in gastric cancer cells.

Results

The results have shown that WWTR1 is overexpressed in 66.4% of the GCA tumor samples. Expression of WWTR1 has a significant inverse correlation with cumulative survival of GCA patients (p < 0.01). WWTR1 positive patients had a mean survival of 56.9 ± 4.4 months, comparing to WWTR1 negative mean survival of 77.3 ± 5.9 months. More importantly, expression of WWTR1 significantly associated with tumor invasion and metastasis (in T stage, p = 0.031; N stage, p < 0.01; and TNM stage, p < 0.001). Furthermore, knockdown of WWTR1 impaired migration of gastric cancer AGS cells.

Conclusions

Our studies have identified WWTR1 as a metastatic biomarker of GCA for poor prognosis, defined a role of WWTR1 in driving metastasis of gastric cancer, and suggested WWTR1 as a potential target for anti-metastatic therapy of GCA.

TAZ sensitizes EGFR wild-type non-small-cell lung cancer to gefitinib by promoting amphiregulin transcription

Comparatively less toxic and more tolerated, epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are recommendable for advanced non-small-cell lung cancer (NSCLC) patients with EGFR-sensitive mutations. Some EGFR wild-type patients with specific biomarkers also show a response to the drug. TAZ is an oncogene closely associated with the therapeutic effect of EGFR-TKIs. However, this association remains to be clarified. This study aimed to clarify the mechanism through which TAZ sensitizes EGFR wild-type NSCLC to gefitinib. We used CCK-8 assays and in vivo experiments to investigate the influence of TAZ on gefitinib in EGFR wild-type NSCLC. To further validate the tumorigenic role of TAZ, we performed Human umbilical vein endothelial cell (HUVEC) tube formation and migration assays. Luciferase reporter assays, quantitative real-time PCR (qPCR), immunoblotting and Chromatin immunoprecipitation collaborated with qPCR illuminated the mechanism through which TAZ caused those phenotypes. The results showed TAZ promoted the angiogenesis of NSCLC cell lines and improved gefitinib sensitivity in EGFR wild-type NSCLC in vitro and in vivo. Luciferase reporter assays and ChIP-qPCR experiments showed TAZ upregulated AREG by promoting its transcription. EGFR signaling pathway was activated as TAZ was highly expressed. Rescue experiments were conducted to confirm the indispensable role of AREG in tumorigenesis and gefitinib sensitivity regulated by TAZ. Our study concluded that TAZ sensitized EGFR wild-type NSCLC to gefitinib through promoting amphiregulin transcription.

Long noncoding RNA NSCLCAT1 increases non-small cell lung cancer cell invasion and migration through the Hippo signaling pathway by interacting with CDH1

Metastatic growth is the leading cause of cancer-related death in non-small cell lung cancer (NSCLC). Metastasis is believed to be initiated by an increase in cell motility mediated by the loss of cell-cell adhesion because of the suppression of E-cadherin [encoded by cadherin 1 ( CDH1)]. However, very little is known about the molecular mechanism of CDH1 regulation. Therefore, we hypothesized that non-small cell lung cancer-associated transcript-1 (NSCLCAT1) suppresses functional CDH1 and mediates the Hippo signaling pathway, resulting in increased cell migration and invasion, and reduced apoptosis. Initially, microarray profiling and target prediction programs were employed to identify whether NSCLCAT1 targets CDH1. Next, quantitative PCR was used to determine the expression pattern of NSCLCAT1 in 114 specimens. The biologic functions of NSCLCAT1 in NSCLC were assessed through the up-regulation and down-regulation of the levels of endogenous NSCLCAT1 with the use of NSCLCAT1 vector or small interfering RNA against NSCLCAT1 in NSCLC cells. Furthermore, the Hippo signaling pathway in NSCLC cells was blocked by applying the verteporfin treatment to have a better understanding on the pivotal role of the Hippo signaling pathway in NSCLC. Microarray expression profiles of long noncoding RNAs, GSE19804 and GSE27262), revealed that NSCLCAT1 was up-regulated in NSCLC. Among patients with NSCLC, we determined that the NSCLCAT1 was robustly induced, whereas CDH1 was suppressed. The luciferase activity determination identified CDH1 as a NSCLCAT1 target. NSCLCAT1 was found to increase cell viability, migration, and invasion and to reduce apoptosis in NSCLC cells. The results from the quantitative PCR and Western blot analysis revealed that NSCLCAT1 modulated the Hippo signaling pathway. Furthermore, the inhibition of the Hippo signaling pathway by verteporfin treatment led to the loss of the effect of NSCLCAT1 on NSCLC cells. In summary, our findings suggested that NSCLCAT1 potentially has a role in NSCLC and NSCLCAT1-mediated regulation of the Hippo signaling pathway through the transcriptional repression of CDH1; therefore, the functional suppression or inhibition of NSCLCAT1 could be used as a novel therapeutic pathway in the control of aggressive and metastatic NSCLC.-Zhao, W., Zhang, L.-N., Wang, X.-L., Zhang, J., Yu, H.-X. Long noncoding RNA NSCLCAT1 increases non-small cell lung cancer cell invasion and migration through the Hippo signaling pathway by interacting with CDH1.

Monitoring Hippo Signaling Pathway Activity Using a Luciferase-based Large Tumor Suppressor (LATS) Biosensor

The Hippo signaling pathway is a conserved regulator of organ size and has important roles in the development and cancer biology. Due to technical challenges, it remains difficult to assess the activity of this signaling pathway and interpret it within a biological context. The existing literature on large tumor suppressor (LATS) relies on methods that are qualitative and cannot easily be scaled-up for screening. Recently, we have developed a bioluminescence-based biosensor to monitor the kinase activity of LATS-a core component of the Hippo kinase cascade. Here, we describe procedures for how this LATS biosensor (LATS-BS) can be used to characterize Hippo pathway regulators. First, we provide a detailed protocol for investigating the effect of an overexpressed protein candidate (e.g., VEGFR2) on LATS activity using the LATS-BS. Then, we show how the LATS-BS can be used for a small-scale kinase inhibitor screen. This protocol can feasibly be scaled-up to perform larger screens, which undoubtedly will identify novel regulators of the Hippo pathway.

MAC30 knockdown involved in the activation of the Hippo signaling pathway in breast cancer cells

Down-regulation of the meningioma-associated protein (MAC30) gene has been found in many solid cancers. This study was carried out to determine the roles and the mechanisms of MAC30 in breast cancer. We used our own data and a public database to analyze the MAC30 mRNA and protein levels in breast cancer tissues. In addition, we established MAC30 knockdown breast cancer cells using MAC30 siRNA. The roles of MAC30 were detected by using the Soft agar assay, Annexin-V-FITC/PI double staining and the Transwell assay. Western blotting was used to analyze the potential mechanism(s) of MAC30 in these cells. We found that MAC30 mRNA and protein were higher in the cancer tissues compared to the matched normal tissues. MAC30 expression was associated with tumor size, tumor differentiation and estrogen receptor (ER) status. Overall survival rate of the patients with low MAC30 expression was obviously higher than the ones with high expression. The apoptotic ratio was lower in MDA-MB-231 and MDA-MB-157 cells with MAC30 expression. By Western blot analysis, we found that increased levels of phosphorylated YAP1, MST1 and LATS1 after MAC30 siRNA transfection in these two cells. In summary, we demonstrate that MAC30 knockdown is involved in the activation of the Hippo signaling pathway.

TAZ induces lung cancer stem cell properties and tumorigenesis by up-regulating ALDH1A1

Recent studies suggest that lung cancer stem cells (CSCs) may play major roles in lung cancer. Therefore, identification of lung CSC drivers may provide promising targets for lung cancer. TAZ is a transcriptional co-activator and key downstream effector of the Hippo pathway, which plays critical roles in various biological processes. TAZ has been shown to be overexpressed in lung cancer and involved in tumorigenicity of lung epithelial cells. However, whether TAZ is a driver for lung CSCs and tumor formation in vivo is unknown. In addition, the molecular mechanism underlying TAZ-induced lung tumorigenesis remains to be determined. In this study, we provided evidence that constitutively active TAZ (TAZ-S89A) is a driver for lung tumorigenesis in vivo in mice and formation of lung CSC. Further RNA-seq and qRT-PCR analysis identified Aldh1a1, a well-established CSC marker, as critical TAZ downstream target and showed that TAZ induces Aldh1a1 transcription by activating its promoter activity through interaction with the transcription factor TEAD. Most significantly, inhibition of ALDH1A1 with its inhibitor A37 or CRISPR gene knockout in lung cancer cells suppressed lung tumorigenic and CSC phenotypes in vitro, and tumor formation in mice in vivo. In conclusion, this study identified TAZ as a novel inducer of lung CSCs and the first transcriptional activator of the stem cell marker ALDH1A1. Most significantly, we identified ALDH1A1 as a critical meditator of TAZ-induced tumorigenic and CSC phenotypes in lung cancer. Our studies provided preclinical data for targeting of TAZ-TEAD-ALDH1A1 signaling to inhibit CSC-induced lung tumorigenesis in the future.

A LATS biosensor screen identifies VEGFR as a regulator of the Hippo pathway in angiogenesis

The Hippo pathway is a central regulator of tissue development and homeostasis, and has been reported to have a role during vascular development. Here we develop a bioluminescence-based biosensor that monitors the activity of the Hippo core component LATS kinase. Using this biosensor and a library of small molecule kinase inhibitors, we perform a screen for kinases modulating LATS activity and identify VEGFR as an upstream regulator of the Hippo pathway. We find that VEGFR activation by VEGF triggers PI3K/MAPK signaling, which subsequently inhibits LATS and activates the Hippo effectors YAP and TAZ. We further show that the Hippo pathway is a critical mediator of VEGF-induced angiogenesis and tumor vasculogenic mimicry. Thus, our work offers a biosensor tool for the study of the Hippo pathway and suggests a role for Hippo signaling in regulating blood vessel formation in physiological and pathological settings.

The Hippo pathway is a major orchestrator of organ development and homeostasis. Here Azad and colleagues develop a biosensor to monitor the activity of the Hippo pathway component LATS and identify VEGF signalling as an upstream regulator of LATS, supporting a role for Hippo signalling during angiogenesis.

Cysteine residues are essential for dimerization of Hippo pathway components YAP2L and TAZ

Hippo signalling pathway is an emerging signalling pathway that plays important roles in organ size control, tumorigenesis, metastasis, stress response, apoptosis, stem cell differentiation and renewal during development and tissue homeostasis. Recent studies reported that human serine/threonine protein kinase, Mst1, a core component of the Hippo pathway can be activated through formation of homodimer. However, it is still unclear whether or not other components of the Hippo pathway are also regulated through dimerization. Here we provide the first evidence that Hippo components and oncoprotein YAP2L and TAZ can form homodimer in vitro and in vivo by forming disulphide bond through cysteine residue(s). We have also shown that the homodimers of YAP2L/TAZ are more stable and showed more oncogenic behaviour than their corresponding monomers as revealed by colony formation and cell transformation assay. Since cysteine post-translational regulation plays important roles in redox signalling, tumorigenesis and drug resistance, further studies on the functional effect of this dimerization through post-translational modulation of cysteine residues in YAP2L/TAZ will provide a significant contribution to our understanding of the roles of YAP2L/TAZ in cancer development and therapy.

HG30, a tetrahydroanthraquinone compound isolated from the roots of Prismatomeris connate, induces apoptosis in human non-small cell lung cancer cells

HG30, a tetrahydroanthraquinone compound isolated from the roots of Prismatomeris connate, was previously shown to inhibit the proliferation of A549 cells. The aim of this study was to evaluate the antitumor activity of HG30 in two non-small cell lung cancer cell lines, A549 and H1299, and to explore potential underlying mechanisms. In cell viability and colony formation assays, HG30 treatment suppressed the proliferation and number of colonies formed by A549 and H1299 cells. Western blot analysis further demonstrated that induction of apoptosis by HG30 in A549 and H1299 cells involves both caspase-dependent apoptosis pathways, including mitochondria- and death receptor-mediated pathways, and an apoptosis-inducing factor (AIF) -associated caspase-independent apoptosis pathway. Specifically, HG30 treatment affected Bcl-2 family proteins and inhibitor of apoptosis protein (IAP) family proteins by down-regulating of Mcl-1, survivin and XIAP and up-regulation of Bid, and Bim.

Identification of microRNA differentially expressed in three subtypes of non-small cell lung cancer and in silico functional analysis

Emerging studies demonstrated that miRNAs played fundamental roles in lung cancer. In this study, we attempted to explore the clinical significance of the miRNA signature in different histological subtypes of non-small cell lung cancer (NSCLC). Three miRNome profiling datasets (GSE19945, GSE25508 and GSE51853) containing lung squamous cell carcinoma (SCC), lung adenocarcinoma (ADC) and large cell lung cancer (LCLC) samples were obtained for bioinformatics and survival analysis. Moreover, pathway enrichment and coexpression network were performed to explore underlying molecular mechanism. MicroRNA-375 (miR-375), miR-203 and miR-205 were identified as differentially expressed miRNAs (DEmiRNAs) which distinguished SCC from other NSCLC subtypes. Pathway enrichment analysis suggested that Hippo signaling pathway was combinatorically affected by above mentioned three miRNAs. Coexpression analysis of three miRNAs and the Hippo signaling pathway related genes were conducted based on another dataset, GSE51852. Four hub genes (TP63, RERE, TJP1 and YWHAE) were identified as the candidate targets of three miRNAs, and three of them (TP63, TJP1 and YWHAE) were validated to be downregulated by miR-203 and miR-375, respectively. Finally, survival analysis further suggested the prognostic value of three-miRNA signature in SCC patients. Taken together, our study compared the miRNA profiles among three histological subtypes of NSCLC, and suggested that a three-miRNA signature might be potential diagnostic and prognostic biomarkers for SCC patients.

Hippo effector YAP directly regulates the expression of PD-L1 transcripts in EGFR-TKI-resistant lung adenocarcinoma

Developments of EGFR-TKI and immunotherapy targeting the PD1/PD-L1 pathway are considered most important medical breakthroughs in lung cancer treatment. Nowadays, 3rd generation EGFR TKI is widely used for T790M positive 1st and 2nd EGFR-TKI resistant lung cancer patients. Immunotherapy is powerful option for lung cancer patients without drug targets and chemotherapy resistant patients. It also has changed the concept of conventional anti-cancer therapy in the point of regulating tumor microenvironment. There are many studies linking these two important pathways. Recent studies demonstrated that PD-L1 expression is significantly correlated to the mutation status of EGFR, and activation of EGFR signaling can also induce the expression of PD-L1. However, the real linker between PD-L1 and EGFR signaling remains to be revealed. Our previous study revealed that the Hippo pathway effector YAP confers EGFR-TKI resistance in lung adenocarcinoma, and inhibition of YAP restores sensitivity to EGFR-TKIs. Thus, we examined whether PD-L1 is relevant, in terms of conferring EGFR-TKI resistance and whether YAP directly regulates the expression of PD-L1 in this context. First, we compared the expression levels of PD-L1 and YAP between EGFR-TKI-resistant PC9 cells and the parental PC9 adenocarcinoma cells. The expression levels of both YAP and PD-L1 were markedly higher in the EGFR-TKI-resistant cells compared to the parental cells, suggesting differential expression pattern between two cell types. YAP knockdown significantly decreased the expression of PD-L1 in the EGFR-TKI-resistant cells, while YAP overexpression increased the expression of PD-L1 in the parental PC9 cells. Then, our results revealed that YAP regulates the transcription of PD-L1, and the YAP/TEAD complex binds to the PD-L1 promoter. Surprisingly, knockdown of PD-L1 was sufficient to decrease cell proliferation and wound healing in the EGFR-TKI-resistant PC9 cells. These data suggest a PD1-independent oncogenic function of PD-L1. The Hippo effector YAP plays a crucial role in linking the PD-L1 and EGFR-TKI resistance by directly regulating the expression of PD-L1 in lung cancer. Targeting PD-L1 directly or via YAP could provide an effective therapeutic strategy for EGFR-TKI-resistant lung adenocarcinoma.

Stearoyl-CoA-desaturase 1 regulates lung cancer stemness via stabilization and nuclear localization of YAP/TAZ

Recent evidences suggest that stearoyl-CoA-desaturase 1 (SCD1), the enzyme involved in monounsaturated fatty acids synthesis, has a role in several cancers. We previously demonstrated that SCD1 is important in lung cancer stem cells survival and propagation. In this article, we first show, using primary cell cultures from human lung adenocarcinoma, that the effectors of the Hippo pathway, Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are required for the generation of lung cancer three-dimensional cultures and that SCD1 knock down and pharmacological inhibition both decrease expression, nuclear localization and transcriptional activity of YAP and TAZ. Regulation of YAP/TAZ by SCD1 is at least in part dependent upon β-catenin pathway activity, as YAP/TAZ downregulation induced by SCD1 blockade can be rescued by the addition of exogenous wnt3a ligand. In addition, SCD1 activation of nuclear YAP/TAZ requires inactivation of the β-catenin destruction complex. In line with the in vitro findings, immunohistochemistry analysis of lung adenocarcinoma samples showed that expression levels of SCD1 co-vary with those of β-catenin and YAP/TAZ. Mining available gene expression data sets allowed to observe that high co-expression levels of SCD1, β-catenin, YAP/TAZ and downstream targets have a strong negative prognostic value in lung adenocarcinoma. Finally, bioinformatics analyses directed to identify which gene combinations had synergistic effects on clinical outcome in lung cancer showed that poor survival is associated with high co-expression of SCD1, β-catenin and the YAP/TAZ downstream target birc5. In summary, our data demonstrate for the first time the involvement of SCD1 in the regulation of the Hippo pathway in lung cancer, and point to fatty acids metabolism as a key regulator of lung cancer stem cells.

Anti-tumor effect of polysaccharide from Hirsutella sinensis on human non-small cell lung cancer and nude mice through intrinsic mitochondrial pathway

Our previous works had proved the structural properties of Hirsutella sinensis polysaccharide-III(HSP-III). Herein, its anti-tumor effect on lung cancer correlated with mitochondrial apoptosis pathway was investigated. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that HSP-III induces the apoptosis of H1299 cells; however the proliferation viability of normal lung epithelial cells is not affected. HSP-III treatment collapses the H1299 cell mitochondrial membrane potential, and western blot analysis of cytochrome C, Bax, caspase-3 and caspase-9 further indicates that apoptotic effects induced by HSP-III is through the mitochondrial pathway. Furthermore, we found the apoptotic effects of HSP-III are triggered by Reactive oxygen species (ROS) generation. Blue native Polyacrylamide Gel-Electrophoresis (PAGE) showed the expressions of mitochondrial respiratory chain complexes I-V were also decreased. Taken together, anti-tumor effect of HSP-III is through intrinsic mitochondrial apoptosis mechanism pathway and involving ROS increasing. Finally, in vivo nude mice experiment, HSP-III attenuated the growth of tumor compared with control. In contrast, N-acetyl-l-cysteine (NAC) could restore the cell apoptosis effects induced by HSP-III. These findings suggest that HSP-III induce apoptosis of H1299 cells and attenuated growth of nude mice tumor in vivo through the intrinsic mitochondrial pathway and stimulating ROS. HSP-III could be a composition for lung cancer treatment.

Whole Exome Sequencing of Growing and Non-Growing Cutaneous Neurofibromas from a Single Patient with Neurofibromatosis Type 1

The growth behaviors of cutaneous neurofibromas in patients with Neurofibromatosis type 1 are highly variable. The role of the germline NF1 mutation, somatic NF1 mutation and mutations at modifying loci, are poorly understood. We performed whole exome sequencing of three growing and three non-growing neurofibromas from a single individual to assess the role of acquired somatic mutations in neurofibroma growth behavior. 1–11 mutations were identified in each sample, including two deleterious NF1 mutations. No trends were present between the types of somatic mutations identified and growth behavior. Mutations in the HIPPO signaling pathway appeared to be overrepresented.