Hippo pathway effector Yap is an ovarian cancer oncogene

Hippo Pathway in Regulating Drug Resistance of Glioblastoma

Glioblastoma (GBM) represents the most common and malignant tumor of the Central Nervous System (CNS), affecting both children and adults. GBM is one of the deadliest tumor types and it shows a strong multidrug resistance (MDR) and an immunosuppressive microenvironment which remain a great challenge to therapy. Due to the high recurrence of GBM after treatment, the understanding of the chemoresistance phenomenon and how to stimulate the antitumor immune response in this pathology is crucial. The deregulation of the Hippo pathway is involved in tumor genesis, chemoresistance and immunosuppressive nature of GBM. This pathway is an evolutionarily conserved signaling pathway with a kinase cascade core, which controls the translocation of YAP (Yes-Associated Protein)/TAZ (Transcriptional Co-activator with PDZ-binding Motif) into the nucleus, leading to regulation of organ size and growth. With this review, we want to highlight how chemoresistance and tumor immunosuppression work in GBM and how the Hippo pathway has a key role in them. We linger on the role of the Hippo pathway evaluating the effect of its de-regulation among different human cancers. Moreover, we consider how different pathways are cross-linked with the Hippo signaling in GBM genesis and the hypothetical mechanisms responsible for the Hippo pathway activation in GBM. Furthermore, we describe various drugs targeting the Hippo pathway. In conclusion, all the evidence described largely support a strong involvement of the Hippo pathway in gliomas progression, in the activation of chemoresistance mechanisms and in the development of an immunosuppressive microenvironment. Therefore, this pathway is a promising target for the treatment of high grade gliomas and in particular of GBM.

Yes-associated protein 1 as a prognostic biomarker and its correlation with telomerase in various cancers

Objectives

The aims of this study were to investigate the expression of Yes-associated protein 1 (YAP1), its prognostic significance, and the correlation between YAP1 and telomerase in various cancers.

Methods

The Gene Expression Profiling Interactive Analysis database was used to analyze RNA sequencing data and the survival rate of patients with various cancers in The Cancer Genome Atlas (TCGA) database. PrognoScan was used to analyze the prognostic value of YAP1 expression in various cancers. Tumor Immune Estimation Resource was used to determine the correlation between YAP1 expression and telomerase in various cancer types based on TCGA data.

Results

The analysis suggested that YAP1 was differentially expressed between tissues of various cancers and non-tumor tissues. High YAP1 expression was also related to a poor prognosis in adrenocortical carcinoma, bladder urothelial carcinoma, and pancreatic adenocarcinoma. Moreover, YAP1 expression was correlated with the expression of telomerase reverse transcriptase and telomerase RNA component in various cancer types.

Conclusion

These results suggest that YAP1 is a potential biomarker with prognostic significance and relevance for oncogene research in various cancer types. The correlation between the expression of YAP1 and telomere-associated genes will help to understand their cancer-promoting mechanisms and interactions.

CircPTK2 (hsa_circ_0003221) Contributes to Laryngeal Squamous Cell Carcinoma by the miR-1278/YAP1 Axis

Laryngeal cancer accounts for 20% of all head and neck malignancies. Laryngeal squamous cell carcinoma (LSCC) is the most common type of laryngeal cancer and is characterized by squamous differentiation, a high mortality rate, and poor prognosis. Accumulating studies have indicated that circular RNAs (circRNAs) are critical regulators in many cancers. CircPTK2 exerts an important regulatory role in several cancers. In this study, we aimed to elucidate the function of circPTK2 (hsa_circ_0003221) in LSCC. Through a series of investigations, we discovered that circPTK2 was significantly upregulated in LSCC tissues cells. Functionally, cell counting kit-8 (CCK-8) and flow cytometry analyses revealed that knockdown of circPTK2 suppressed LSCC cell viability and the cell cycle while promoting cell apoptosis. Notably, silencing circPTK2 inhibited tumor growth in vivo. Mechanistically, circPTK2 functioned as a molecular sponge of miR-1278 to upregulate YAP1 expression in LSCC cells. Moreover, YAP1 knockdown inhibited malignant phenotypes of LSCC cells. The rescue experiments showed that YAP1 overexpression reversed the effects of circPTK2 on LSCC cells. Therefore, we concluded that circPTK2 facilitates LSCC progression through the miR-1278/YAP1 axis.

Downregulation of LINC01508 contributes to cisplatin resistance in ovarian cancer via the regulation of the Hippo-YAP pathway

BACKGROUND

Some long non-coding RNAs (lncRNAs) have been found to contribute to cisplatin resistance. Here, we identified a novel lncRNA that was downregulated in cisplatin-resistant to ovarian cancer (OC) cells and aimed to examine the contribution of LINC01508 to cisplatin resistance in OC cells.

METHODS

Differences in the lncRNA expression profile between OV2008 and C13K cells were assessed by lncRNA expression microarray. The expression of LINC01508 in ovarian epithelial cells, four OC cells, and OC, benign ovary tumor and normal ovary, cisplatin-resistant and non-resistant OC specimens were evaluated by quantitative real-time polymerase chain reaction (qPCR). The role of LINC01508 in OC cisplatin-resistant was evaluated by cell counting kit-8 (CCK-8), flow cytometry, colony formation, wound healing, Transwell, and tumor growth inhibition study in vivo. The clinical associations of LINC01508 in OC were evaluated using correlation analysis. The effects of verteporfin (VP) on cisplatin were explored to reveal the function of the hippo-YAP pathway on the cisplatin tolerance of C13K.

RESULTS

LINC01508 was downregulated in cisplatin-resistant OC cells and platinum-resistant OC tissue (p<0.01). LINC01508 downregulation was correlated with tumor size, residual tumor, and platinum resistance. The overexpression of LINC01508 improves in vitro and in vivo sensitivity to cisplatin while predicts the poor overall survival which need further follow-up research. The increased level of LINC01508 could suppress the cisplatin resistance of OC cells through the inhibition of the hippo-YAP pathway.

CONCLUSIONS

The study proposes that dysregulation of LINC01508 expression results in resistance of OC to cisplatin through the inhibition of the hippo-YAP pathway.

A Yes-Associated Protein (YAP) and Insulin-Like Growth Factor 1 Receptor (IGF-1R) Signaling Loop Is Involved in Sorafenib Resistance in Hepatocellular Carcinoma

The role of a YAP-IGF-1R signaling loop in HCC resistance to sorafenib remains unknown.

METHOD

Sorafenib-resistant cells were generated by treating naïve cells (HepG2215 and Hep3B) with sorafenib. Different cancer cell lines from databases were analyzed through the ONCOMINE web server. BIOSTORM-LIHC patient tissues (46 nonresponders and 21 responders to sorafenib) were used to compare YAP mRNA levels. The HepG2215_R-derived xenograft in SCID mice was used as an in vivo model. HCC tissues from a patient with sorafenib failure were used to examine differences in YAP and IGF-R signaling.

RESULTS

Positive associations exist among the levels of YAP, IGF-1R, and EMT markers in HCC tissues and the levels of these proteins increased with sorafenib failure, with a trend of tumor-margin distribution in vivo. Blocking YAP downregulated IGF-1R signaling-related proteins, while IGF-1/2 treatment enhanced the nuclear translocation of YAP in HCC cells through PI3K-mTOR regulation. The combination of YAP-specific inhibitor verteporfin (VP) and sorafenib effectively decreased cell viability in a synergistic manner, evidenced by the combination index (CI).

CONCLUSION

A YAP-IGF-1R signaling loop may play a role in HCC sorafenib resistance and could provide novel potential targets for combination therapy with sorafenib to overcome drug resistance in HCC.

The hippo pathway: A master regulator of liver metabolism, regeneration, and disease

The liver is the only visceral organ in the body with a tremendous capacity to regenerate in response to insults that induce inflammation, cell death, and injury. Liver regeneration is a complicated process involving a well-orchestrated activation of non-parenchymal cells in the injured area and proliferation of undamaged hepatocytes. Furthermore, the liver has a Hepatostat, defined as adjustment of its volume to that required for homeostasis. Understanding the mechanisms that control different steps of liver regeneration is critical to informing therapies for liver repair, to help patients with liver disease. The Hippo signaling pathway is well known for playing an essential role in the control and regulation of liver size, regeneration, stem cell self-renewal, and liver cancer. Thus, the Hippo pathway regulates dynamic cell fates in liver, and in absence of its downstream effectors YAP and TAZ, liver regeneration is severely impaired, and the proliferative expansion of liver cells blocked. We will mainly review upstream mechanisms activating the Hippo signaling pathway following partial hepatectomy in mouse model and patients, its roles during different steps of liver regeneration, metabolism, and cancer. We will also discuss how targeting the Hippo signaling cascade might improve liver regeneration and suppress liver tumorigenesis.

Hippo Signaling Pathway as a New Potential Target in Non-Melanoma Skin Cancers: A Narrative Review

Non-melanoma skin cancers (NMSCs), including basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), are the most frequently diagnosed cancers in humans, however, their exact pathogenesis is not fully understood. In recent years, it has been hypothesized that the recently discovered Hippo pathway could play a detrimental role in cutaneous carcinogenesis, but no direct connections have been made. The Hippo pathway and its effector, YAP, are responsible for tissue growth by accelerating cell proliferation, however, YAP upregulation and overexpression have also been reported in numerous types of tumors. There is also evidence that disrupted YAP/Hippo signaling is responsible for cancer growth, invasion, and metastasis. In this short review, we will explore whether the Hippo pathway is an important regulator of skin carcinogenesis and if it could be a promising target for future therapies.

RASAL2 Confers Collateral MEK/EGFR Dependency in Chemoresistant Triple-Negative Breast Cancer

PURPOSE

While chemotherapy remains the standard treatment for triple-negative breast cancer (TNBC), identifying and managing chemoresistant tumors has proven elusive. We sought to discover hallmarks and therapeutically actionable features of refractory TNBC through molecular analysis of primary chemoresistant TNBC specimens.

EXPERIMENTAL DESIGN

We performed transcriptional profiling of tumors from a phase II clinical trial of platinum chemotherapy for advanced TNBC (TBCRC-009), revealing a gene expression signature that identified de novo chemorefractory tumors. We then employed pharmacogenomic data mining, proteomic and other molecular studies to define the therapeutic vulnerabilities of these tumors.

RESULTS

We reveal the RAS-GTPase-activating protein (RAS-GAP) RASAL2 as an upregulated factor that mediates chemotherapy resistance but also an exquisite collateral sensitivity to combination MAP kinase kinase (MEK1/2) and EGFR inhibitors in TNBC. Mechanistically, RASAL2 GAP activity is required to confer kinase inhibitor sensitivity, as RASAL2-high TNBCs sustain basal RAS activity through suppression of negative feedback regulators SPRY1/2, together with EGFR upregulation. Consequently, RASAL2 expression results in failed feedback compensation upon co-inhibition of MEK1/2 and EGFR that induces synergistic apoptosis in vitro and in vivo. In patients with TNBC, high RASAL2 levels predict clinical chemotherapy response and long-term outcomes, and are associated via direct transcriptional regulation with activated oncogenic Yes-Associated Protein (YAP). Accordingly, chemorefractory patient-derived TNBC models exhibit YAP activation, high RASAL2 expression, and tumor regression in response to MEK/EGFR inhibitor combinations despite well-tolerated intermittent dosing.

CONCLUSIONS

These findings identify RASAL2 as a mediator of TNBC chemoresistance that rewires MAPK feedback and cross-talk to confer profound collateral sensitivity to combination MEK1/2 and EGFR inhibitors.

The Drosophila gonads: models for stem cell proliferation, self-renewal, and differentiation

The male and female gonads of Drosophila melanogaster have developed into powerful model systems for both the study of stem cell behaviours, and for understanding how stem cell misregulation can lead to cancers. Using these systems, one is able to observe and manipulate the resident stem cell populations in vivo with a great deal of licence. The tractability of the testis and ovary also allow researchers to explore a range of cellular mechanisms, such as proliferation and polarity, as well as the influence exerted by the local environment through a host of highly-conserved signalling pathways. Importantly, many of the cellular behaviours and processes studied in the Drosophila testis and ovary are known to be disrupted, or otherwise misregulated, in human tumourigenic cells. Here, we review the mechanisms relating to stem cell behaviour, though we acknowledge there are many other fascinating aspects of gametogenesis, including the invasive behaviour of migratory border cells in the Drosophila ovary that, though relevant to the study of tumourigenesis, will unfortunately not be covered.

YAP inhibits autophagy and promotes progression of colorectal cancer via upregulating Bcl-2 expression

Colorectal cancer (CRC) is one of the most aggressive and lethal cancers. The role of autophagy in the pathobiology of CRC is intricate, with opposing functions manifested in different cellular contexts. The Yes-associated protein (YAP), a transcriptional coactivator inactivated by the Hippo tumor-suppressor pathway, functions as an oncoprotein in a variety of cancers. In this study, we found that YAP could negatively regulate autophagy in CRC cells, and consequently, promote tumor progression of CRC in vitro and in vivo. Mechanistically, YAP interacts with TEAD forming a complex to upregulate the transcription of the apoptosis-inhibitory protein Bcl-2, which may subsequently facilitate cell survival by suppressing autophagy-related cell death; silencing Bcl-2 expression could alleviate YAP-induced autophagy inhibition without affecting YAP expression. Collectively, our data provide evidence for YAP/Bcl-2 as a potential therapeutic target for drug exploration against CRC.

Regulation of ferroptosis in cancer cells by YAP/TAZ and Hippo pathways: The therapeutic implications

Ferroptosis is a novel form of iron-dependent cell death characterized by lipid peroxidation. While the importance and disease relevance of ferroptosis is gaining recognition, much remains unknown about various genetic and non-genetic determinants of ferroptosis. Hippo signaling pathway is an evolutionarily conserved pathway that responds to various environmental cues and controls organ size, cell proliferation, death, and self-renewal capacity. In cancer biology, Hippo pathway is a potent tumor suppressing mechanism and its dysregulation contributes to apoptosis evasion, cancer development, metastasis, and treatment resistance. Hippo dysregulation leads to aberrant activation of YAP and TAZ, the two major transcription co-activators of TEADs, that induce the expression of genes triggering tumor-promoting phenotypes, including enhanced cell proliferation, self-renewal and apoptosis inhibition. The Hippo pathway is regulated by the cell-cell contact and cellular density/confluence. Recently, ferroptosis has also been found being regulated by the cellular contact and density. The YAP/TAZ activation under low density, while confers apoptosis resistance, renders cancer cells sensitivity to ferroptosis. These findings establish YAP/TAZ and Hippo pathways as novel determinants of ferroptosis. Therefore, inducing ferroptosis may have therapeutic potential for YAP/TAZ-activated chemo-resistant and metastatic tumor cells. Reciprocally, various YAP/TAZ-targeting treatments under clinical development may confer ferroptosis resistance, limiting the therapeutic efficacy.

New Insights into YES-Associated Protein Signaling Pathways in Hematological Malignancies: Diagnostic and Therapeutic Challenges

Simple Summary

YES-associated protein (YAP) is a co-transcriptional activator that binds to transcriptional factors to increase the rate of transcription of a set of genes, and it can intervene in the onset and progression of different tumors. Most of the data in the literature refer to the effects of the YAP system in solid neoplasms. In this review, we analyze the possibility that YAP can also intervene in hematological neoplasms such as lymphomas, multiple myeloma, and acute and chronic leukemias, modifying the phenomena of cell proliferation and cell death. The possibilities of pharmacological intervention related to the YAP system in an attempt to use its modulation therapeutically are also discussed.

Abstract

The Hippo/YES-associated protein (YAP) signaling pathway is a cell survival and proliferation-control system with its main activity that of regulating cell growth and organ volume. YAP operates as a transcriptional coactivator in regulating the onset, progression, and treatment response in numerous human tumors. Moreover, there is evidence suggesting the involvement of YAP in the control of the hematopoietic system, in physiological conditions rather than in hematological diseases. Nevertheless, several reports have proposed that the effects of YAP in tumor cells are cell-dependent and cell-type-determined, even if YAP usually interrelates with extracellular signaling to stimulate the onset and progression of tumors. In the present review, we report the most recent findings in the literature on the relationship between the YAP system and hematological neoplasms. Moreover, we evaluate the possible therapeutic use of the modulation of the YAP system in the treatment of malignancies. Given the effects of the YAP system in immunosurveillance, tumorigenesis, and chemoresistance, further studies on interactions between the YAP system and hematological malignancies will offer very relevant information for the targeting of these diseases employing YAP modifiers alone or in combination with chemotherapy drugs.

The Cancer Stem Cell Niche in Ovarian Cancer and Its Impact on Immune Surveillance

Ovarian cancer is an aggressive gynaecological cancer with extremely poor prognosis, due to late diagnosis as well as the development of chemoresistance after first-line therapy. Research advances have found stem-like cells present in ovarian tumours, which exist in a dynamic niche and persist through therapy. The stem cell niche interacts extensively with the immune and non-immune components of the tumour microenvironment. Significant pathways associated with the cancer stem cell niche have been identified which interfere with the immune component of the tumour microenvironment, leading to immune surveillance evasion, dysfunction and suppression. This review aims to summarise current evidence-based knowledge on the cancer stem cell niche within the ovarian cancer tumour microenvironment and its effect on immune surveillance. Furthermore, the review seeks to understand the clinical consequences of this dynamic interaction by highlighting current therapies which target these processes.

YAP promotes sorafenib resistance in hepatocellular carcinoma by upregulating survivin

BACKGROUND

Sorafenib is the standard first-line treatment for advanced hepatocellular carcinoma (HCC), but its use is hampered by secondary drug resistance. Yes-associated protein (YAP) is a downstream effector of the Hippo signaling pathway, which is crucial for liver tumorigenesis. As yet, however, the mechanism underlying sorafenib resistance and the role of YAP therein is not fully understood and needs to be explored further.

METHODS

Western blotting, flow cytometry and CCK-8 assays were used to assess the role of YAP in HCC sorafenib resistance. Next, qRT-PCR and Western blotting were performed to identify survivin as a YAP downstream effector, and rescue experiments were performed to confirm that YAP induces sorafenib resistance via survivin. Additionally, Western blotting, flow cytometry and in vivo xenograft models were used to evaluate the effect of verteporfin in combination with sorafenib on HCC.

RESULTS

We found that sorafenib enhances YAP nuclear accumulation and activation, thereby promoting sorafenib resistance through inhibiting apoptosis in HCC cells. In addition, we found that survivin acts as a downstream mediator of YAP to resist sorafenib-induced apoptosis. Pharmacological inhibition of YAP by verteporfin increased the sensitivity of HCC cells to sorafenib and reversed sorafenib resistance. Moreover, verteporfin in combination with sorafenib significantly suppressed in vivo HCC tumor growth.

CONCLUSIONS

Our data indicate that YAP promotes sorafenib resistance through upregulation of survivin expression in HCC cells. Targeting YAP may be a therapeutic strategy to improve the antitumor effects of sorafenib in HCC.

Epithelial cell transforming 2 is regulated by Yes-associated protein 1 and mediates pancreatic cancer progression and metastasis

Pancreatic ductal adenocarcinoma (PDAC) is highly metastatic and represents one of the deadliest forms of human cancers. Previous studies showed that activation of Yes-associated protein 1 (YAP1) plays a key role in malignant transformation in the pancreas. In this study, we found that YAP1 regulates the expression of epithelial cell transforming 2 (ECT2), a guanine nucleotide exchange factor for Rho-like GTPases. By immunohistochemistry analysis of human tissues, we show that ECT2 is highly expressed in primary PDAC and liver metastasis but not in normal pancreas. These correlations were also observed in a mouse model of PDAC, where pancreatic transformation is driven by mutants of Kras and Trp53. Notably, nuclear ECT2 is upregulated in the transition from preneoplastic lesions to PDAC. High levels of YAP1 or ECT2 expression correlates with the poor overall survival rate of patients with PDAC. We further demonstrate that ECT2 is required for pancreatic cancer cell proliferation and migration in vitro. Finally, using a syngeneic orthotopic xenograft mouse model for pancreatic cancer, we found that ablation of ECT2 expression reduces pancreatic cancer growth and dissemination to the liver. These findings highlight the critical role of ECT2 in promoting pancreatic cancer growth and metastasis and provides insights into the development of novel methods for early detection and treatment.NEW & NOTEWORTHY Pancreatic ductal adenocarcinoma is one of the deadliest forms of human cancers. In this study, we identified a novel signaling mechanism involved in PDAC progression and metastasis. Yes-associated protein 1 mediates the expression of epithelial cell transforming 2, which is elevated in PDAC and correlates with poor survival. Epithelial cell transforming 2 is required for PDAC growth and metastasis. This study provides insights into the development of novel methods for early detection and treatment of PDAC.

Homoharringtonine Exerts Anti-tumor Effects in Hepatocellular Carcinoma Through Activation of the Hippo Pathway

Hepatocellular carcinoma (HCC) is the most prevalent subtype of liver cancer with a mortality rate of approximately 3–6/100,000 and is the third leading cause of cancer-related death worldwide. Although several small-molecule drugs have been developed for the treatment of HCC, the choice of an agent for patients who require systemic chemotherapy at an advanced stage is still limited. The Hippo pathway is an evolutionarily conserved tumor suppressive pathway commonly dysregulated in HCC, which makes it a promising target for anti-HCC therapies. Homoharringtonine (HHT) is an FDA-approved anti-leukemia drug with proven strong anti-tumor activity in solid tumors. In this study, we found that HHT could significantly inhibit HCC cell growth by suppressing cell proliferation and colony formation. Moreover, HHT repressed cell invasion and migration remarkably. Additionally, HHT induced cell cycle arrest at S phase and promoted apoptosis. Most importantly, we showed that HHT-induced apoptosis was a consequence of the Hippo pathway activation. Consistently, the MST1/2 inhibitor, XMU-MP-1, could restore cell viability and reverse HHT-induced cell apoptosis. Furthermore, in vivo results confirmed the tumor inhibitory effect of HHT. Taken together, our findings suggest that HHT is a potential alternative therapeutic agent for the treatment of HCC.

Association of variably methylated tumour DNA regions with overall survival for invasive lobular breast cancer

Background

Tumour DNA methylation profiling has shown potential to refine disease subtyping and improve the diagnosis and prognosis prediction of breast cancer. However, limited data exist regarding invasive lobular breast cancer (ILBC). Here, we investigated the genome-wide variability of DNA methylation levels across ILBC tumours and assessed the association between methylation levels at the variably methylated regions and overall survival in women with ILBC.

Methods

Tumour-enriched DNA was prepared by macrodissecting formalin-fixed paraffin embedded (FFPE) tumour tissue from 130 ILBCs diagnosed in the participants of the Melbourne Collaborative Cohort Study (MCCS). Genome-wide tumour DNA methylation was measured using the HumanMethylation 450K (HM450K) BeadChip array. Variably methylated regions (VMRs) were identified using the DMRcate package in R. Cox proportional hazards regression models were used to assess the association between methylation levels at the ten most significant VMRs and overall survival. Gene set enrichment analyses were undertaken using the web-based tool Metaspace. Replication of the VMR and survival analysis findings was examined using data retrieved from The Cancer Genome Atlas (TCGA) for 168 ILBC cases. We also examined the correlation between methylation and gene expression for the ten VMRs of interest using TCGA data.

Results

We identified 2771 VMRs (P < 10⁻⁸) in ILBC tumours. The ten most variably methylated clusters were predominantly located in the promoter region of the genes: ISM1, APC, TMEM101, ASCL2, NKX6, HIST3H2A/HIST3H2BB, HCG4P3, HES5, CELF2 and EFCAB4B. Higher methylation level at several of these VMRs showed an association with reduced overall survival in the MCCS. In TCGA, all associations were in the same direction, however stronger than in the MCCS. The pooled analysis of the MCCS and TCGA data showed that methylation at four of the ten genes was associated with reduced overall survival, independently of age and tumour stage; APC: Hazard Ratio (95% Confidence interval) per one-unit M-value increase: 1.18 (1.02–1.36), TMEM101: 1.23 (1.02–1.48), HCG4P3: 1.37 (1.05–1.79) and CELF2: 1.21 (1.02–1.43). A negative correlation was observed between methylation and gene expression for CELF2 (R = − 0.25, P = 0.001), but not for TMEM101 and APC.

Conclusions

Our study identified regions showing greatest variability across the ILBC tumour genome and found methylation at several genes to potentially serve as a biomarker of survival for women with ILBC.

Deep Pathway Analysis V2.0: A Pathway Analysis Framework Incorporating Multi-Dimensional Omics Data

Pathway analysis is essential in cancer research particularly when scientists attempt to derive interpretation from genome-wide high-throughput experimental data. If pathway information is organized into a network topology, its use in interpreting omics data can become very powerful. In this paper, we propose a topology-based pathway analysis method, called DPA V2.0, which can combine multiple heterogeneous omics data types in its analysis. In this method, each pathway route is encoded as a Bayesian network which is initialized with a sequence of conditional probabilities specifically designed to encode directionality of regulatory relationships defined in the pathway. Unlike other topology-based pathway tools, DPA is capable of identifying pathway routes as representatives of perturbed regulatory signals. We demonstrate the effectiveness of our model by applying it to two well-established TCGA data sets, namely, breast cancer study (BRCA) and ovarian cancer study (OV). The analysis combines mRNA-seq, mutation, copy number variation, and phosphorylation data publicly available for both TCGA data sets. We performed survival analysis and patient subtype analysis and the analysis outcomes revealed the anticipated strengths of our model. We hope that the availability of our model encourages wet lab scientists to generate extra data sets to reap the benefits of using multiple data types in pathway analysis. The majority of pathways distinguished can be confirmed by biological literature. Moreover, the proportion of correctly indentified pathways is 10 percent higher than previous work where only mRNA-seq and mutation data is incorporated for breast cancer patients. Consequently, such an in-depth pathway analysis incorporating more diverse data can give rise to the accuracy of perturbed pathway detection.

YAP in pancreatic cancer: oncogenic role and therapeutic strategy

Pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), remains a fatal disease with few efficacious treatments. The Hippo signaling pathway, an evolutionarily conserved signaling module, plays critical roles in tissue homeostasis, organ size control and tumorigenesis. The transcriptional coactivator yes-associated protein (YAP), a major downstream effector of the Hippo pathway, is associated with various human cancers including PDAC. Considering its importance in cancer, YAP is emerging as a promising therapeutic target. In this review, we summarize the current understanding of the oncogenic role and regulatory mechanism of YAP in PDAC, and the potential therapeutic strategies targeting YAP.

Regulation of Hippo signaling pathway in cancer: A MicroRNA perspective

Recent studies have suggested that Hippo signaling is not only involved in controlling organ size in Drosophila but can also regulate cell proliferation, tissue homeostasis, differentiation, apoptosis and regeneration. Any dysregulation of Hippo signaling, especially the hyper activation of its downstream effectors YAP/TAZ, can lead to uncontrolled cell proliferation and malignant transformation. In majority of cancers, expression of YAP/TAZ is extremely high and this increased expression of YAP/TAZ has been shown to be an independent predictor of prognosis and indicator of increased cell proliferation, metastasis and poor survival. In this review, we have summarized the most recent findings about the cross talk of Hippo signaling pathway with other signaling pathways and its regulation by different miRNAs in various cancer types. Recent evidence has suggested that Hippo pathway is also involved in mediating the resistance of different cancer cells to chemotherapeutic drugs and in a few cancer types, this is brought about by regulating miRNAs. Therefore, the delineation of the underlying mechanisms regulating the chemotherapeutic resistance might help in developing better treatment options. This review has attempted to provide an overview of different drugs/options which can be utilized to target oncogenic YAP/TAZ proteins for therapeutic interventions.

Convergence of Plasma Metabolomics and Proteomics Analysis to Discover Signatures of High-Grade Serous Ovarian Cancer

Simple Summary

In-time diagnosing ovarian cancer, intractable cancer that has no symptoms can increase the survival of women. The aim of this study was to discover biomarkers from liquid biopsy samples using multi-omics approach, metabolomics and proteomics for the diagnosis of ovarian cancer. To verify our biomarker candidates, we conducted comparative analysis with other previous published studies. Despite the limitations of non-invasive samples, our findings are able to discover emerging properties through the interplay between metabolites and proteins and mechanism-based biomarkers through integrated protein and metabolite analysis.

Abstract

The 5-year survival rate in the early and late stages of ovarian cancer differs by 63%. In addition, a liquid biopsy is necessary because there are no symptoms in the early stage and tissue collection is difficult without using invasive methods. Therefore, there is a need for biomarkers to achieve this goal. In this study, we found blood-based metabolite or protein biomarker candidates for the diagnosis of ovarian cancer in the 20 clinical samples (10 ovarian cancer patients and 10 healthy control subjects). Plasma metabolites and proteins were measured and quantified using mass spectrometry in ovarian cancer patients and control groups. We identified the differential abundant biomolecules (34 metabolites and 197 proteins) and statistically integrated molecules of different dimensions to better understand ovarian cancer signal transduction and to identify novel biological mechanisms. In addition, the biomarker reliability was verified through comparison with existing research results. Integrated analysis of metabolome and proteome identified emerging properties difficult to grasp with the single omics approach, more reliably interpreted the cancer signaling pathway, and explored new drug targets. Especially, through this analysis, proteins (PPCS, PMP2, and TUBB) and metabolites (L-carnitine and PC-O (30:0)) related to the carnitine system involved in cancer plasticity were identified.

STK3 Suppresses Ovarian Cancer Progression by Activating NF-κB Signaling to Recruit CD8+ T-Cells

Serine/threonine protein kinase-3 (STK3) is a critical molecule of the Hippo pathway but little is known about its biological functions in the ovarian cancer development. We demonstrated the roles of STK3 in ovarian cancer. Existing databases were used to study the expression profile of STK3. STK3 was significantly downregulated in OC patients, and the low STK3 expression was correlated with a poor prognosis. In vitro cell proliferation, apoptosis, and migration assays, and in vivo subcutaneous xenograft tumor models were used to determine the roles of STK3. The overexpression of STK3 significantly inhibited cell proliferation, apoptosis, and migration of ovarian cancer cells in vitro and tumor growth in vivo. Bisulfite sequencing PCR analysis was performed to validate the methylation of STK3 in ovarian cancer. RNA sequencing and gene set enrichment analysis (GSEA) were used to compare the transcriptome changes in the STK3 overexpression ovarian cancer and control cells. The signaling pathway was analyzed by western blotting. STK3 promoted the migration of CD8⁺ T-cells by activating nuclear transcription factor κB (NF-κB) signaling. STK3 is a potential predictor of OC. It plays an important role in suppressing tumor growth of ovarian cancer and in chemotaxis of CD8⁺ T-cells.

The YAP-Interacting Phosphatase SHP2 Can Regulate Transcriptional Coactivity and Modulate Sensitivity to Chemotherapy in Cholangiocarcinoma

The Hippo pathway effector Yes-associated protein (YAP) is localized to the nucleus and transcriptionally active in a number of tumor types, including a majority of human cholangiocarcinomas. YAP activity has been linked to chemotherapy resistance and has been shown to rescue KRAS and BRAF inhibition in RAS/RAF-driven cancers; however, the underlying mechanisms of YAP-mediated chemoresistance have yet to be elucidated. Herein, we report that the tyrosine phosphatase SHP2 directly regulates the activity of YAP by dephosphorylating pYAPY357 even in the setting of RAS/RAF mutations, and that diminished SHP2 phosphatase activity is associated with chemoresistance in cholangiocarcinomas. A screen for YAP-interacting tyrosine phosphatases identified SHP2, and characterization of cholangiocarcinomas cell lines demonstrated an inverse relationship between SHP2 levels and pYAPY357. Human sequencing data demonstrated lower SHP2 levels in cholangiocarcinomas tumors as compared with normal liver. Cell lines with low SHP2 expression and higher levels of pYAPY357 were resistant to gemcitabine and cisplatin. In cholangiocarcinomas cells with high levels of SHP2, pharmacologic inhibition or genetic deletion of SHP2 increased YAPY357 phosphorylation and expression of YAP target genes, including the antiapoptotic regulator MCL1, imparting resistance to gemcitabine and cisplatin. In vivo evaluation of chemotherapy sensitivity demonstrated significant resistance in xenografts with genetic deletion of SHP2, which could be overcome by utilizing an MCL1 inhibitor. IMPLICATIONS: These findings demonstrate a role for SHP2 in regulating YAP activity and chemosensitivity, and suggest that decreased phosphatase activity may be a mechanism of chemoresistance in cholangiocarcinoma via a MCL1-mediated mechanism.

Endothelin-1 axis fosters YAP-induced chemotherapy escape in ovarian cancer

The majority of ovarian cancer (OC) patients recur with a platinum-resistant disease. OC cells activate adaptive resistance mechanisms that are only partially described. Here we show that OC cells can adapt to chemotherapy through a positive-feedback loop that favors chemoresistance. In platinum-resistant OC cells we document that the endothelin-1 (ET-1)/endothelin A receptor axis intercepts the YAP pathway. This cross-talk occurs through the LATS/RhoA/actin-dependent pathway and contributes to prevent the chemotherapy-induced apoptosis. Mechanistically, β-arrestin1 (β-arr1) and YAP form a complex shaping TEAD-dependent transcriptional activity on the promoters of YAP target genes, including EDN1, which fuels a feed-forward signaling circuit that sustains a platinum-tolerant state. The FDA approved dual ET-1 receptor antagonist macitentan in co-therapy with cisplatin sensitizes resistant cells to the platinum-based therapy, reducing their metastatic potential. Furthermore, high ET_AR/YAP gene expression signature is associated with a poor platinum-response in OC patients. Collectively, our findings identify in the networking between ET-1 and YAP pathways an escape strategy from chemotherapy. ET-1 receptor blockade interferes with such adaptive network and enhances platinum-induced apoptosis, representing a promising therapeutic opportunity to restore drug sensitivity in OC patients.

Long-Term Glucose Restriction with or without β-Hydroxybutyrate Enrichment Distinctively Alters Epithelial-Mesenchymal Transition-Related Signalings in Ovarian Cancer Cells

The beneficial impacts of the ketogenic diet and metabolic reprograming were recently reported for ovarian cancer patients. In this study, the effects of glucose restriction with or without beta-hydroxybutyrate (bHB) enrichment were studied in drug-resistant CD133high A2780CP and CD133low SK-OV-3 ovarian cancer cells to scrutinize the impact of experimental ketosis on ATP production, epithelial to mesenchymal transition (EMT), and related signaling pathways including Wnt, Hippo, and Hedgehog. Cells were adapted and maintained for a month with restricted levels of glucose (250 mg/l) with or without the therapeutic concentration of bHB (5 mM). Quantitative PCR, Western blot analysis, flow cytometry, chemiluminescence, and wound healing assay were used in this study. Glucose restriction and bHB enrichment reduced the stemness marker and diminished In Vitro migration in both cell lines. Glucose restriction significantly reduced ATP levels in both cells, but bHB enrichment was partially compensated for the ATP levels solely in SK-OV-3 cells. Glucose restriction mainly inhibited the Wnt pathway in the CD133high A2780CP cells, but the Hedgehog pathway was the main target in CD133low SK-OV-3 cells. In Conclusion, Prior targeted evaluations of key genes' expression would help to predict the distinctive impacts of metabolic fuels and to optimize the efficacy of ketogenic diets.

TEAD4 promotes tumor development in patients with lung adenocarcinoma via ERK signaling pathway

OBJECTIVE

Whether TEAD4 itself plays a vital role in the tumorigenesis and development of lung adenocarcinoma remains unclear. In our study, we aim to investigate the expression pattern and biological functions of TEAD4 and further investigate the potential mechanisms.

METHODS

Clinical tumor and paired normal samples were collected for preparing tissue microarray. Western blot and immunohistochemical (IHC) staining of TEAD4 expression in these tissues were conducted to explore the expression pattern. Moreover, A549 cell line was select for investigating the function of TEAD4 for lung adenocarcinoma in vitro and in vivo. RNA sequencing was finally performed to further detect the potential downstream genes.

RESULTS

The elevated TEAD4 expression level was observed in tumor tissues and the patients with higher TEAD4 expression tended to have worse overall survival. The knockdown of TEAD4 inhibits A549 cells proliferation ability and migration ability. A total of 431 differentially expressed genes (DEGs), including 239 down-regulated genes and 191 up-regulated genes, were finally identified and some of DEGs were validated. Moreover, knockdown of TEAD4 led to the down-regulation of pERK, which maybe the potential TEAD4-targeted signaling pathway to play the pro-tumorigenic function.

CONCLUSIONS

The expression level of TEAD4 is high in lung adenocarcinoma tumor tissues and positively associated with worse prognosis. Up-regulation of TEAD4 may lead to excessive transcription and phosphorylation of ERK proteins and therefore accelerates the process of tumor development. Our results demonstrate that overexpression of TEAD4 is a new mechanism of dysregulation of Hippo pathway.

Hippo signaling disruption and ovarian follicle activation in infertile patients

The Hippo signaling pathway, which is important in organ size regulation, is present in organisms from the fly to mammals. Disruption of the Hippo signaling pathway leads to increased nuclear translocation of the effector Yes-associated protein (YAP), resulting in the expression of cystein-rich 61, connective tissue growth factor, and nephroblastoma overexpressed (CCN) growth factors and baculoviral inhibitors of apoptosis repeat containing (BIRC) apoptosis inhibitors to increase organ sizes. Furthermore, genome-wide knockdown of genes in insect cells demonstrated that actin polymerization promoted nuclear translocation of YAP. In the mammalian ovary, we demonstrated the expression of Hippo signaling pathway genes and showed that ovarian fragmentation increased actin polymerization, leading to YAP nuclear translocation and increased expression of cystein-rich 61, CCN growth factors and BIRC apoptosis inhibitors, followed by enhanced follicle growth. Here we summarize evidence suggesting the role of mechanical stress on follicle growth in the ovary and describe recent use of ovary-damaging procedures to treat ovarian infertility. Ovarian fragmentation, together with in vitro incubation with Akt-stimulating drugs, formed the basis of an in vitro activation (IVA) therapy to treat patients with premature ovarian insufficiency, whereas ovarian fragmentation alone (drug-free IVA) was successful in treating patients with premature ovarian insufficiency with recent menses cessation. For middle-aged women with poor ovarian responses and diminished ovarian reserve, drug-free IVA was also effective in promoting follicle growth for infertility treatment. In addition, an in vivo follicle activation approach based on laparoscopic ovarian incision showed promise for patients with resistant ovary syndrome. With initial success using mechanical disruption approaches, future investigation could evaluate possibilities to refine mechanical methods and to locally administer actin polymerization-enhancing drugs for ovarian infertility treatment.

Bioinformatic analysis reveals MIR502 as a potential tumour suppressor in ovarian cancer

BACKGROUND

Ovarian cancer (OC) is a major cause of death among women due to the lack of early screening methods and its complex pathological progression. Increasing evidence has indicated that microRNAs regulate gene expression in tumours by interacting with mRNAs. Although the research regarding OC and microRNAs is extensive, the vital role of MIR502 in OC remains unclear.

METHODS

We integrated two microRNA expression arrays from GEO to identify differentially expressed genes. The Kaplan-Meier method was used to screen for miRNAs that had an influence on survival outcome. Upstream regulators of MIR502 were predicted by JASPAR and verified by ChIP-seq data. The LinkedOmics database was used to study genes that were correlated with MIR502. Gene Set Enrichment Analysis (GSEA) was conducted for functional annotation with GO and KEGG pathway enrichment analyses by using the open access WebGestalt tool. We constructed a PPI network by using STRING to further explore the core proteins.

RESULTS

We found that the expression level of MIR502 was significantly downregulated in OC, which was related to poor overall survival. NRF1, as an upstream regulator of MIR502, was predicted by JASPAR and verified by ChIP-seq data. In addition, anti-apoptosis and pro-proliferation genes in the Hippo signalling pathway, including CCND1, MYC, FGF1 and GLI2, were negatively regulated by MIR502, as shown in the GO and KEGG pathway enrichment results. The PPI network further demonstrated that CCND1 and MYCN were at core positions in the development of ovarian cancer.

CONCLUSIONS

MIR502, which is regulated by NRF1, acts as a tumour suppressor gene to accelerate apoptosis and suppress proliferation by targeting the Hippo signalling pathway in ovarian cancer.

The roles of miRNAs' clinical efficiencies in the colorectal cancer pathobiology: A review article

MiRNAs (microRNAs) are defined as micro directors and regulators of gene expression. Since altered miRNA expression is signified in the pathobiology of diverse cancers such as colorectal cancers (CRCs), these molecules are described as therapeutic targets, either. Manipulation of miRNAs could lead to further therapy for chemo and radio-resistant CRCs. The usage of microRNAs has indicated prominent promise in the prognosis and diagnosis of CRC, because of their unique expression pattern associated with cancer types and malignancies. Nowadays, many researchers are analyzing the correlation between miRNA polymorphisms and cancer risk. With continuous incompatibility in colorectal cancer (CRC) miRNAs expression data, it is critical to move toward the content of a "pre-laboratory" analysis to speed up efficient accuracy medicine and translational study. Pathway study for the highest expressed miRNAs- regulated target genes resulted in the identification of a considerable number of genes associated with CRC pathway including PI3K, TGFβ, and APC. In this review, we aimed to collect fruitful information about miRNAs and their potential roles in CRC, and provide a meta-analysis of the most frequently studied miRNAs in association with the disease.

Targeting Cancer Stem Cells to Overcome Therapy Resistance in Ovarian Cancer

Ovarian cancer is the most lethal gynecological malignancy due to its late detection and high recurrence rate. Resistance to conventional platinum-based therapies and metastasis are attributed to a population of cells within tumors called cancer stem cells, which possess stem-like features and are able to recapitulate new tumors. Recent studies have deepened the understanding of the biology of ovarian cancer stem cells and their special properties and have identified multiple markers and signaling pathways responsible for their self-renewal abilities. Targeting cancer stem cells represents the most promising strategy for overcoming therapy resistance and reducing mortality in ovarian cancer, but further efforts must be made to improve our understanding of the mechanisms involved in therapy resistance. In this review, we summarize our current knowledge about ovarian cancer stem cells, their involvement in metastasis and their interactions with the tumor microenvironment; we also discuss the therapeutic approaches that are being developed to target them to prevent tumor relapse.

Targeting Hippo signaling pathway by phytochemicals in cancer therapy

The current era of cancer research has been continuously advancing upon identifying novel aspects of tumorigenesis and the principal mechanisms behind the unleashed proliferation, invasion, drug resistance and immortality of cancer cells in hopes of exploiting these findings to achieve a more effective treatment for cancer. In pursuit of this goal, the identification of the first components of an extremely important regulatory pathway in Drosophila melanogaster that largely determines cell fate during the developmental stages, ended up in the discovery of the highly sophisticated Hippo signaling cascade. Soon after, it was revealed that deregulation of the components of this pathway either via mutations or through epigenetic alterations can be observed in a vast variety of tumors and these alterations greatly contribute to the neoplastic transformation of cells, their survival, growth and resistance to therapy. As more hidden aspects of this pathway such as its widespread entanglement with other major cellular signaling pathways are continuously being uncovered, many researchers have sought over the past decade to find ways of therapeutic interventions targeting the major components of the Hippo cascade. To date, various approaches such as the use of exogenous targeting miRNAs and different molecular inhibitors have been recruited herein, among which naturally occurring compounds have shown a great promise. On such a basis, in the present work we review the current understanding of Hippo pathway and the most recent evidence on targeting its components using natural plant-derived phytochemicals.

Expression and prognostic significance of YAP, TAZ, TEAD4 and p73 in human laryngeal cancer

OBJECTIVES

The Hippo signaling pathway plays a critical role in organ size control and tissue homeostasis and its perturbation is associated with tumorigenesis. YAP (Yes associated protein) and TAZ (transcriptional co-activator with PDZ- binding motif) are the major nuclear effectors of the Hippo pathway interacting with TEADs (TEA domain) and p73 transcriptional factors to regulate gene expression. Altered expression of the above proteins promotes tumor initiation, progression and metastasis in a variety of cancer types. This study addresses their expression and prognostic significance in human laryngeal carcinoma.

METHODS

Protein expression of YAP, TAZ, TEAD4 and p73 was examined by immunohistochemistry in 121 human laryngeal squamous cell carcinomas. Correlations with clinicopathological data and survival were evaluated.

RESULTS

All proteins were overexpressed in human laryngeal carcinomas compared to non-neoplastic adjacent epithelium. High expression of YAP, TAZ, TEAD4 and p73 correlated significantly with high grade, advanced stage, supraglottic location of tumor, nodal metastases and recurrence. Furthermore, high expression of all proteins was significantly associated with poor overall and disease- free survival. p73 expression proved to be an independent predictive factor of survival and YAP expression proved to be an independent predictive factor of disease recurrence.

CONCLUSIONS

Deregulation of the expression of the Hippo pathway proteins is implicated in human laryngeal carcinogenesis and YAP and p73 have prognostic significance in the outcome of the disease.

The HIPPO pathway in gynecological malignancies

The Hippo pathway has been initially discovered by screening genes that regulate organ size in Drosophila. Recent studies have highlighted the role of the Hippo pathway in controlling organ size, tissue homeostasis and regeneration, and signaling dysregulation, especially the overactivation of the transcriptional coactivator YAP/TAZ, which leads to uncontrolled cell growth and malignant transformation. The core components of the Hippo pathway may initiate tumorigenesis by inducing tumor stem cells and proliferation, ultimately leading to metastasis and drug resistance, which occurs extensively in gynecological malignancies, including cervical cancer, ovarian cancer, and endometrial cancer. In this review, we attempt to systematically summarize recent progress in our understanding of the mechanism of Hippo pathway regulation in tumorigenesis and the mechanisms that underlie alterations during gynecological malignancies, as well as new therapeutic strategies.

Downregulation of MYPT1 increases tumor resistance in ovarian cancer by targeting the Hippo pathway and increasing the stemness

BACKGROUND

Ovarian cancer is one of the most common and malignant cancers, partly due to its late diagnosis and high recurrence. Chemotherapy resistance has been linked to poor prognosis and is believed to be linked to the cancer stem cell (CSC) pool. Therefore, elucidating the molecular mechanisms mediating therapy resistance is essential to finding new targets for therapy-resistant tumors.

METHODS

shRNA depletion of MYPT1 in ovarian cancer cell lines, miRNA overexpression, RT-qPCR analysis, patient tumor samples, cell line- and tumorsphere-derived xenografts, in vitro and in vivo treatments, analysis of data from ovarian tumors in public transcriptomic patient databases and in-house patient cohorts.

RESULTS

We show that MYPT1 (PPP1R12A), encoding myosin phosphatase target subunit 1, is downregulated in ovarian tumors, leading to reduced survival and increased tumorigenesis, as well as resistance to platinum-based therapy. Similarly, overexpression of miR-30b targeting MYPT1 results in enhanced CSC-like properties in ovarian tumor cells and is connected to the activation of the Hippo pathway. Inhibition of the Hippo pathway transcriptional co-activator YAP suppresses the resistance to platinum-based therapy induced by either low MYPT1 expression or miR-30b overexpression, both in vitro and in vivo.

CONCLUSIONS

Our work provides a functional link between the resistance to chemotherapy in ovarian tumors and the increase in the CSC pool that results from the activation of the Hippo pathway target genes upon MYPT1 downregulation. Combination therapy with cisplatin and YAP inhibitors suppresses MYPT1-induced resistance, demonstrating the possibility of using this treatment in patients with low MYPT1 expression, who are likely to be resistant to platinum-based therapy.

A TAZ-ANGPTL4-NOX2 Axis Regulates Ferroptotic Cell Death and Chemoresistance in Epithelial Ovarian Cancer

Ovarian cancer is the deadliest gynecologic cancer. Despite recent advances, clinical outcomes remain poor, necessitating novel therapeutic approaches. To investigate metabolic susceptibility, we performed nutrigenetic screens on a panel of clear cell and serous ovarian cancer cells and identified cystine addiction and vulnerability to ferroptosis, a novel form of regulated cell death. Our results may have therapeutic potential, but little is known about the determinants of ferroptosis susceptibility in ovarian cancer. We found that vulnerability to ferroptosis in ovarian cancer cells is enhanced by lower cell confluency. Because the Hippo pathway effectors Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) are recognized as sensors of cell density, and TAZ is the predominant effector in the tested ovarian cancer cell lines, we investigated the role of TAZ in ferroptosis of ovarian cancer. TAZ removal confers ferroptosis resistance, while TAZS89A overexpression sensitizes cells to ferroptosis. In addition, we found that lower TAZ level in chemo-resistant recurrent ovarian cancer is responsible for reduced ferroptosis susceptibility. The integrative genomic analysis identified ANGPTL4 as a direct TAZ-regulated target gene that sensitizes ferroptosis by activating NOX2. Collectively, cell density-regulated ferroptosis in ovarian cancer is mediated by TAZ through the regulation of the ANGPTL4-NOX2 axis, suggesting therapeutic potentials for ovarian cancers and other TAZ-activated tumors. IMPLICATIONS: This study reveals that TAZ promotes ferroptosis in ovarian cancers by regulating ANGPTL4 and NOX, offering a novel therapeutic potential for ovarian tumors with TAZ activation.

Long non-coding RNA expression identified by microarray analysis: Candidate biomarkers in human acral lentiginous melanoma

Melanoma is a rare but fatal form of skin cancer and acral lentiginous melanoma (ALM) is one of its most common types. Long non-coding RNA (lncRNA) has emerged as a crucial molecule in the development and progression of human cancers, and several studies have revealed that lncRNAs may be associated with the pathogenesis, progression and metastasis of melanoma. To demonstrate the association between ALM and lncRNAs, microarray analysis was performed in tumor and adjacent non-tumor tissues. A total of 4,488 lncRNAs and 3,913 mRNAs were identified to be differentially expressed in these samples. Among them, 2,211 and 2,277 lncRNAs were upregulated and downregulated in the ALM samples compared with adjacent tissues, respectively. In addition, 1,191 and 2,722 mRNAs were upregulated and downregulated, respectively. Additionally, five randomly selected lncRNAs (fold-change >2; P<0.05) were validated by reverse transcription-quantitative PCR. An lncRNA and mRNA co-expression network and competing endogenous network analysis were also constructed. In summary, the results of the present study may reveal a novel mechanism associated with the pathogenesis and malignant biological processes of ALM and indicate that lncRNAs may serve as potential targets for the treatment of ALM.

YAP promotes gastric cancer cell survival and migration/invasion via the ERK/endoplasmic reticulum stress pathway

Yes-associated protein (YAP) has been reported to serve an important role in gastric cancer cell survival and migration. However, the underlying mechanism remains unclear. The aim of present study was to identify the underlying mechanism through which Yap sustains gastric cancer viability and migration. The results of the present study demonstrated that YAP expression was upregulated in gastric cancer MKN-28/74 cells compared with normal gastric GES-1 cells. Functional studies revealed that silencing of YAP inhibited gastric cancer MKN-28/74 cell viability and invasion. Mechanistically, YAP may promote gastric cancer cell survival and migration/invasion by inhibiting the endoplasmic reticulum (ER) stress pathway. In addition, YAP may regulate ER stress by activating the ERK signaling pathway. The results of the present study suggested that YAP may be a tumor promoter in gastric cancer and act through the ERK/ER stress pathway; therefore, YAP may have potential implications for new approaches to gastric cancer therapy.

The prognostic value of YAP1 on clinical outcomes in human cancers

BACKGROUND

As an important downstream factor in the Hippo pathway, yes-associated protein 1(YAP1) has been detected to be elevated in various cancers and demonstrated to play a role in tumor development. Therefore, we evaluated by a meta-analysis the prognostic value of YAP1 in cancer patients.

RESULTS

Sixty-eight studies with 8631 patients were identified. The results indicated that YAP1 overexpression predicted unfavorable patient prognosis in studies with overall survival (OS) (HR=1.76, 95%CI: 1.50-2.06, p<0.001) and disease-free survival (DFS) (HR=1.39, 95%CI: 1.22-1.59, p<0.001), as well as in studies with recurrence-free survival (RFS) (HR=2.38, 95%CI: 1.73-3.27, p<0.001), and disease-specific survival (DSS) (HR=2.04, 95%CI: 1.55-2.70, p<0.001). Meanwhile, YAP1 overexpression was also observed to be significantly associated with worse OS in GEPIA (HR=1.2, p<0.001).

CONCLUSIONS

Overexpression of YAP1 showed great association with poorer prognosis in patients with various cancers, particularly liver cancer. Therefore, YAP1 might be an important prognostic marker and a novel target of cancer therapy.

METHODS

We searched for potential publications in several online databases and retrieved relevant data. Overall and subgroup analyses were performed. Begg's and Egger's tests were used to assess publication bias. Online dataset GEPIA was used to generate the survival curves and verify the prognostic role of YAP1 in patients with tumors.

Profiling and bioinformatics analyses reveal differential circular RNA expression in ovarian cancer

Ovarian cancer (OC) is the deadliest form of gynecologic malignancy, with the majority of patients being diagnosed only once the disease reaches an advanced stage owing to a lack of available biomarkers capable of accurately detecting the disease. Stable circular RNAs (circRNAs) can be found at high levels in exosomes, and there is evidence to suggest that they may be viable diagnostic biomarkers for certain cancers. However, circRNAs in the serum of OC patients have rarely been evaluated to date. We therefore sought to investigate serum circRNA profiles of OC patients, and to explore whether these sorts of circRNAs could be used to detect early OC, serving as biomarkers of disease that may allow for the earlier treatment thereof. Second-generation sequencing was used to screen differentially expressed circRNAs in OC patient serum and also in the serum obtained from healthy controls, and circRNA expression was confirmed by qPCR. A bioinformatics-based approach was then used to assess what biological functions might be affected be the altered regulation of these RNA molecules. We further conducted GO, KEGG, and network analyses to further explore the expression of circRNAs. We detected 178 differentially expressed circRNAs in OC patient serum, of which 175 were up-regulated and 3 were down-regulated. We validated 5 of these identified circRNAs by qPCR to confirm their expression, and further found these RNAs to be closely linked with FC gamma R-mediated phagocytosis, VEGF signaling, Transcriptional misregulation in cancer, Chemokine signaling, ErbB signaling, and TNF signaling based on conducted analyses. This study provides a profile of circRNAs in OC patient serum, revealing a pattern of dysregulation of these RNAs associated with OC. Our bioinformatics analysis suggested that these circRNAs are likely related to OC development, and as such they may be viable novel OC biomarkers.

The YAP1-NMU Axis Is Associated with Pancreatic Cancer Progression and Poor Outcome: Identification of a Novel Diagnostic Biomarker and Therapeutic Target

Yes-associated protein (YAP)-1 is highly upregulated in pancreatic cancer and associated with tumor progression. However, little is known about the role of YAP1 and related genes in pancreatic cancer. Here, we identified target genes regulated by YAP1 and explored their role in pancreatic cancer progression and the related clinical implications. Analysis of different pancreatic cancer databases showed that Neuromedin U (NMU) expression was positively correlated with YAP1 expression in the tumor group. The Cancer Genome Atlas data indicated that high YAP1 and NMU expression levels were associated with poor mean and overall survival. YAP1 overexpression induced NMU expression and transcription and promoted cell motility in vitro and tumor metastasis in vivo via upregulation of epithelial-mesenchymal transition (EMT), whereas specific inhibition of NMU in cells stably expressing YAP1 had the opposite effect in vitro and in vivo. To define this functional association, we identified a transcriptional enhanced associate domain (TEAD) binding site in the NMU promoter and demonstrated that YAP1-TEAD binding upstream of the NMU gene regulated its transcription. These results indicate that the identified positive correlation between YAP1 and NMU is a potential novel drug target and biomarker in metastatic pancreatic cancer.

Characteristics of in Vivo Model Systems for Ovarian Cancer Studies

An understanding of the molecular pathogenesis and heterogeneity of ovarian cancer holds promise for the development of early detection strategies and novel, efficient therapies. In this review, we discuss the advantages and limitations of animal models available for basic and preclinical studies. The fruit fly model is suitable mainly for basic research on cellular migration, invasiveness, adhesion, and the epithelial-to-mesenchymal transition. Higher-animal models allow to recapitulate the architecture and microenvironment of the tumor. We discuss a syngeneic mice model and the patient derived xenograft model (PDX), both useful for preclinical studies. Conditional knock-in and knock-out methodology allows to manipulate selected genes at a given time and in a certain tissue. Such models have built our knowledge about tumor-initiating genetic events and cell-of-origin of ovarian cancers; it has been shown that high-grade serous ovarian cancer may be initiated in both the ovarian surface and tubal epithelium. It is postulated that clawed frog models could be developed, enabling studies on tumor immunity and anticancer immune response. In laying hen, ovarian cancer develops spontaneously, which provides the opportunity to study the genetic, biochemical, and environmental risk factors, as well as tumor initiation, progression, and histological origin; this model can also be used for drug testing. The chick embryo chorioallantoic membrane is another attractive model and allows the study of drug response.

Impact of Taurine on the proliferation and apoptosis of human cervical carcinoma cells and its mechanism

BACKGROUND

Cervical cancer has the fourth highest incidence and mortality rate of all cancers in women worldwide; it seriously harms their physical and mental health. The aim of this study was to observe the roles and preliminary mechanism of Taurine (Tau)-induced apoptosis in cervical cancer cells.

METHODS

Cells from the human cervical cancer cell line SiHa were transfected with the recombinant plasmid pEGFP-N1-MST1 (mammalian sterile 20-like kinase 1); then, the cell proliferation activity was analyzed by the MTT assay, cell apoptosis by flow cytometry, and the related protein levels by Western blotting.

RESULTS

Tau inhibited the proliferation of SiHa cells and induced apoptosis in these cells (the apoptotic rate was 21.95% in the Tau 160 mmol/L group and 30% in the Tau 320 mmol/L group), upregulated the expression of the MST1 (control, 0.53; Tau 40-320 mmol/L groups, 0.84-1.45) and Bax (control, 0.45; Tau 40-320 mmol/L groups, 0.64-1.51) proteins (P < 0.01), and downregulated the expression of Bcl-2 (control, 1.28, Tau 40-320 mmol/L groups, 0.93-0.47) (P < 0.01). The overexpression of MST1 promoted the apoptosis of SiHa cells, enhanced the apoptosis-inductive effects of Tau (P < 0.01), upregulated the expression of the proapoptotic proteins p73, p53, PUMA (p53 upregulated modulator of apoptosis), and caspase-3, and promoted the phosphorylation of YAP (Yes-associated protein).

CONCLUSIONS

Tau inhibited the proliferation and induced the apoptosis of cervical cancer SiHa cells. The MST1 protein plays an important role in the Tau-induced apoptosis of cervical cancer cells.

β-arrestin1/YAP/mutant p53 complexes orchestrate the endothelin A receptor signaling in high-grade serous ovarian cancer

The limited clinical response observed in high-grade serous ovarian cancer (HG-SOC) with high frequency of TP53 mutations (mutp53) might be related to mutp53-driven oncogenic pathway network. Here we show that β-arrestin1 (β-arr1), interacts with YAP, triggering its cytoplasmic-nuclear shuttling. This interaction allows β-arr1 to recruit mutp53 to the YAP-TEAD transcriptional complex upon activation of endothelin-1 receptors (ET-1R) in patient-derived HG-SOC cells and in cell lines bearing mutp53. In parallel, β-arr1 mediates the ET-1R-induced Trio/RhoA-dependent YAP nuclear accumulation. In the nucleus, ET-1 through β-arr1 orchestrates the tethering of YAP and mutp53 to YAP/mutp53 target gene promoters, including EDN1 that ensures persistent signals. Treatment of patient-derived xenografts reveals synergistic antitumoral and antimetastatic effects of the dual ET-1R antagonist macitentan in combination with cisplatinum, shutting-down the β-arr1-mediated YAP/mutp53 transcriptional programme. Furthermore, ETAR/β-arr1/YAP gene signature correlates with a worst prognosis in HG-SOC. These findings support effective combinatorial treatment for repurposing the ET-1R antagonists in HG-SOC.

The Expression of Yes-Associated Protein (YAP) Maintains Putative Cancer Stemness and Is Associated with Poor Prognosis in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is resistant to most chemotherapeutic agents. Yes-associated protein (YAP) is related to tumor progression; however, its role in ICC remains unknown. We investigated the mechanism underlying YAP-mediated cancer progression by focusing on the property of cancer stem cells (CSCs) in ICC. Immunohistochemistry results revealed the positive YAP expression in 37 of 52 resected ICC cases. Those with positive YAP expression showed poor prognosis in Kaplan-Meier analysis (P = 0.023). YAP expression was associated with vimentin and the putative CSC marker, hepatic oval cell marker 6 (OV-6). The knockdown of YAP expression using specific siRNAs in ICC cells decreased octamer-binding transcription factor 4 (OCT4) expression in Western blot analyses and OV-6 and CD133 expression in flow cytometry analysis. Verteporfin, a YAP inhibitor, decreased N-cadherin and OCT4 expression in Western blot analyses. In vitro sphere formation and anoikis resistance assays revealed the impairment in CSC property and anoikis resistance in response to the decrease in YAP expression. Verteporfin treatment activated the protein kinase B/mechanistic target of rapamycin signaling pathway and dramatically impaired IL-6-stimulated STAT3 phosphorylation in ICC cells. The combination of verteporfin and rapamycin, an inhibitor of mechanistic target of rapamycin phosphorylation, inhibited cell proliferation and tumor growth. In conclusion, verteporfin regulates multiple signaling pathways and, in combination with rapamycin, might be a promising therapeutic strategy for ICC treatment.

Activation of Aurora A kinase increases YAP stability via blockage of autophagy

Transcription cofactor Yes-associated protein (YAP) plays an important role in cancer progression. Here, we found that Aurora A kinase expression was positively correlated with YAP in lung cancer. Aurora A depletion suppresses lung cancer cell colony formation, which could be reversed by YAP ectopic overexpression. In addition, activation of Aurora A increases YAP protein abundance through maintaining its protein stability. Consistently, the transcriptional activity of YAP is increased upon Aurora A activation. We further showed that shAURKA suppressed YAP expression in the absence of Lats1/2, indicating that Aurora A regulates YAP independently of Hippo pathway. Instead, Aurora A induced blockage of autophagy to up-regulate YAP expression. Collectively, our findings provide insights into regulatory mechanisms of YAP expression in lung cancer development.

Hippo Signaling in Cancer: Lessons From Drosophila Models

Hippo pathway was initially identified through genetic screens for genes regulating organ size in fruitflies. Recent studies have highlighted the role of Hippo signaling as a key regulator of homeostasis, and in tumorigenesis. Hippo pathway is comprised of genes that act as tumor suppressor genes like hippo (hpo) and warts (wts), and oncogenes like yorkie (yki). YAP and TAZ are two related mammalian homologs of Drosophila Yki that act as effectors of the Hippo pathway. Hippo signaling deficiency can cause YAP- or TAZ-dependent oncogene addiction for cancer cells. YAP and TAZ are often activated in human malignant cancers. These transcriptional regulators may initiate tumorigenic changes in solid tumors by inducing cancer stem cells and proliferation, culminating in metastasis and chemo-resistance. Given the complex mechanisms (e.g., of the cancer microenvironment, and the extrinsic and intrinsic cues) that overpower YAP/TAZ inhibition, the molecular roles of the Hippo pathway in tumor growth and progression remain poorly defined. Here we review recent findings from studies in whole animal model organism like Drosophila on the role of Hippo signaling regarding its connection to inflammation, tumor microenvironment, and other oncogenic signaling in cancer growth and progression.