YAP is overexpressed in clear cell renal cell carcinoma and its knockdown reduces cell proliferation and induces cell cycle arrest and apoptosis

TM4SF19 controls GABP-dependent YAP transcription in head and neck cancer under oxidative stress conditions

Tobacco and alcohol are risk factors for human papillomavirus-negative head and neck squamous cell carcinoma (HPV- HNSCC), which arises from the mucosal epithelium of the upper aerodigestive tract. Notably, despite the mutagenic potential of smoking, HPV- HNSCC exhibits a low mutational load directly attributed to smoking, which implies an undefined role of smoking in HPV- HNSCC. Elevated YAP (Yes-associated protein) mRNA is prevalent in HPV- HNSCC, irrespective of the YAP gene amplification status, and the mechanism behind this upregulation remains elusive. Here, we report that oxidative stress, induced by major risk factors for HPV- HNSCC such as tobacco and alcohol, promotes YAP transcription via TM4SF19 (transmembrane 4 L six family member 19). TM4SF19 modulates YAP transcription by interacting with the GABP (Guanine and adenine-binding protein) transcription factor complex. Mechanistically, oxidative stress induces TM4SF19 dimerization and topology inversion in the endoplasmic reticulum membrane, which in turn protects the GABPβ1 subunit from proteasomal degradation. Conversely, depletion of TM4SF19 impairs the survival, proliferation, and migration of HPV- HNSCC cells, highlighting the potential therapeutic relevance of targeting TM4SF19. Our findings reveal the roles of the key risk factors of HPV- HNSCC in tumor development via oxidative stress, offering implications for upcoming therapeutic approaches in HPV- HNSCC.

Network Analysis and Basic Experiments on the Inhibition of Renal Cancer Proliferation and Migration by Alpinetin through PI3K/AKT/ mTOR Pathway

BACKGROUND

Alpinetin, a natural flavonoid, has been shown to have anticancer effects on many tumors. This study investigated the antitumor effect of alpinetin on renal clear cell carcinoma (ccRCC).

METHODS

Network Pharmacology analysis was carried out on the targets and molecular mechanisms of alpinetin treating ccRCC. The Annexin V PE/7-AAD kit was used to detect apoptosis. Flow cytometry and Cell Counting Kit-8 (CCK-8) were used to detect cell proliferation and cycle. A 24-well transwell chamber and the ibidi scratch insertion performed cell migration analysis. The protein expression of the target molecule was detected by Western blotting. Nude mouse tumorigenesis assays were used to determine the in vivo antitumor effects of alpinetin.

RESULTS

The network pharmacology revealed that GAPDH, HRAS, SRC, EGFR, and AKT1 are the main targets of alpinetin in treating ccRCC, with the PI3K/AKT signaling pathway being the main pathway of action. We found that alpinetin could significantly inhibit the proliferation and migration of ccRCC cells by inducing apoptosis. In addition, alpinetin also inhibited the cycle progression of ccRCC cells by blocking them in the G1 phase. Furthermore, in vivo and in vitro, alpinetin could inhibit the activation of an important pathway involved in the proliferation and migration of ccRCC cells, namely the PI3K/Akt pathway.

CONCLUSION

Alpinetin can inhibit the growth of ccRCC cells by inhibiting the activation of the PI3K/Akt pathway and can be a potential anti-cancer drug for ccRCC.

Cellular Impacts of Striatins and the STRIPAK Complex and Their Roles in the Development and Metastasis in Clinical Cancers (Review)

Striatins (STRNs) are generally considered to be cytoplasmic proteins, with lower expression observed in the nucleus and at cell-cell contact regions. Together with protein phosphatase 2A (PP2A), STRNs form the core region of striatin-interacting phosphatase and kinase (STRIPAK) complexes through the coiled-coil region of STRN proteins, which is crucial for substrate recruitment. Over the past two decades, there has been an increasing amount of research into the biological and cellular functions of STRIPAK members. STRNs and the constituent members of the STRIPAK complex have been found to regulate several cellular functions, such as cell cycle control, cell growth, and motility. Dysregulation of these cellular events is associated with cancer development. Importantly, their roles in cancer cells and clinical cancers are becoming recognised, with several STRIPAK components found to have elevated expression in cancerous tissues compared to healthy tissues. These molecules exhibit significant diagnostic and prognostic value across different cancer types and in metastatic progression. The present review comprehensively summarises and discusses the current knowledge of STRNs and core STRIPAK members, in cancer malignancy, from both cellular and clinical perspectives.

High TEAD4 Expression is Associated With Aggressive Clear Cell Renal Cell Carcinoma, Regardless of YAP1 Expression

Yes-associated protein 1 (YAP1) and transcriptional coactivator TEA domain transcription factor 4 (TEAD4) are the main effectors of the Hippo signaling pathway. Deregulation of the Hippo signaling pathway significantly impacts tumorigenesis and tumor progression. We evaluated the mRNA expression level of YAP1 and TEAD4 using the Gene Expression Profiling Interactive Analysis database and investigated the roles of YAP1 and TEAD4 in 349 surgically resected clear cell renal cell carcinoma (CCRCC) samples through immunohistochemical analysis. High YAP1 and TEAD4 expression were observed in 57 (16.3%) and 131 (37.5%) cases, respectively. High YAP1 expression was associated with a low nuclear grade only. High TEAD4 expression was significantly associated with large tumor size, high nuclear grade, lymphovascular invasion, advanced pT classification, advanced clinical stage, sarcomatous differentiation, and metastasis. CCRCC with YAP1-low/TEAD4-high expression was significantly associated with aggressive clinicopathological variables and poor outcomes. For CCRCC, higher tumor stage, sarcomatous differentiation, and metastasis were the independent prognostic factors for overall survival (OS) and disease-free survival (DFS). High TEAD4 expression was significantly associated with short OS and DFS but was not an independent prognostic factor. High TEAD4 and YAP1-low/TEAD4-high expression significantly correlated with adverse clinicopathological factors and worse OS and DFS in patients with CCRCC. YAP1 expression was not significantly associated with clinicopathological factors or patient survival. Therefore, TEAD4 plays a critical role in CCRCC tumor progression independent of YAP1 and may be a potential biomarker and therapeutic target for CCRCC.

Heterogeneity of Hippo signalling activity in different histopathologic subtypes of renal cell carcinoma

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

The Regulation of the Hippo Pathway by Intercellular Junction Proteins

The Hippo pathway is an evolutionarily conserved pathway that serves to promote cell death and differentiation while inhibiting cellular proliferation across species. The downstream effectors of this pathway, yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), are considered vital in promoting the output of the Hippo pathway, with activation of upstream kinases negatively regulating YAP/TAZ activity. The upstream regulation of the Hippo pathway is not entirely understood on a molecular level. However, several studies have shown that numerous cellular and non-cellular mechanisms such as cell polarity, contact inhibition, soluble factors, mechanical forces, and metabolism can convey external stimuli to the intracellular kinase cascade, promoting the activation of key components of the Hippo pathway and therefore regulating the subcellular localisation and protein activity of YAP/TAZ. This review will summarise what we have learnt about the role of intercellular junction-associated proteins in the activation of this pathway, including adherens junctions and tight junctions, and in particular our latest findings about the desmosomal components, including desmoglein-3 (DSG3), in the regulation of YAP signalling, phosphorylation, and subcellular translocation.

YAP1 activation promotes epithelial-mesenchymal transition and cell survival of renal cell carcinoma cells under shear stress

Renal cell carcinoma (RCC) is characterized by substantial vasculatures and increased fluid movement in tumor microenvironment, and the fluid shear stress modulates malignance, extravasation and metastatic seeding of tumor cells. However, the precise mechanism remains largely unclear. In this study, we found that low shear stress induced the Yes-associated protein (YAP1) activation and nuclear localization in RCC cells, as well as the downregulation of phosphorylated YAP1 at Ser127. Moreover, inhibition of ROCK or RhoA partially abolished YAP1 accumulation in the nucleus, and targeting YAP1 activation by small molecular inhibitor or genetic manipulation decreased the low shear stress-induced epithelial-mesenchymal transition (EMT) of RCC cells, and led to a decreased expression of N-cadherin as accompanied by downregulation of Snail1 and Twist, accompanied by high shear stress-induced cell apoptosis. Salvianolic acid B, an aqueous component of danshen (Salvia miltiorrhiza), inhibited YAP1 and Hippo signaling activation, and abrogated low shear stress-induced EMT as a consequence. Taken together, our study suggests YAP1 is a fluid mechanosensor that transforms mechanical stimuli to cell signals, thereby facilitates anoikis resistance and tumor metastasis.

The Hippo signaling pathway in leukemia: function, interaction, and carcinogenesis

Cancer can be considered as a communication disease between and within cells; nevertheless, there is no effective therapy for the condition, and this disease is typically identified at its late stage. Chemotherapy, radiation, and molecular-targeted treatment are typically ineffective against cancer cells. A better grasp of the processes of carcinogenesis, aggressiveness, metastasis, treatment resistance, detection of the illness at an earlier stage, and obtaining a better therapeutic response will be made possible. Researchers have discovered that cancerous mutations mainly affect signaling pathways. The Hippo pathway, as one of the main signaling pathways of a cell, has a unique ability to cause cancer. In order to treat cancer, a complete understanding of the Hippo signaling system will be required. On the other hand, interaction with other pathways like Wnt, TGF-β, AMPK, Notch, JNK, mTOR, and Ras/MAP kinase pathways can contribute to carcinogenesis. Phosphorylation of oncogene YAP and TAZ could lead to leukemogenesis, which this process could be regulated via other signaling pathways. This review article aimed to shed light on how the Hippo pathway interacts with other cellular signaling networks and its functions in leukemia.

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.

The Hippo Signaling Pathway in Cancer: A Cell Cycle Perspective

Simple Summary

Cancer is increasingly viewed as a cell cycle disease in that the dysregulation of the cell cycle machinery is a common feature in cancer. The Hippo signaling pathway consists of a core kinase cascade as well as extended regulators, which together control organ size and tissue homeostasis. The aberrant expression of cell cycle regulators and/or Hippo pathway components contributes to cancer development, and for this reason, we specifically focus on delineating the roles of the Hippo pathway in the cell cycle. Improving our understanding of the Hippo pathway from a cell cycle perspective could be used as a powerful weapon in the cancer battlefield.

Abstract

Cell cycle progression is an elaborate process that requires stringent control for normal cellular function. Defects in cell cycle control, however, contribute to genomic instability and have become a characteristic phenomenon in cancers. Over the years, advancement in the understanding of disrupted cell cycle regulation in tumors has led to the development of powerful anti-cancer drugs. Therefore, an in-depth exploration of cell cycle dysregulation in cancers could provide therapeutic avenues for cancer treatment. The Hippo pathway is an evolutionarily conserved regulator network that controls organ size, and its dysregulation is implicated in various types of cancers. Although the role of the Hippo pathway in oncogenesis has been widely investigated, its role in cell cycle regulation has not been comprehensively scrutinized. Here, we specifically focus on delineating the involvement of the Hippo pathway in cell cycle regulation. To that end, we first compare the structural as well as functional conservation of the core Hippo pathway in yeasts, flies, and mammals. Then, we detail the multi-faceted aspects in which the core components of the mammalian Hippo pathway and their regulators affect the cell cycle, particularly with regard to the regulation of E2F activity, the G1 tetraploidy checkpoint, DNA synthesis, DNA damage checkpoint, centrosome dynamics, and mitosis. Finally, we briefly discuss how a collective understanding of cell cycle regulation and the Hippo pathway could be weaponized in combating cancer.

Lappaol F, an anticancer agent, inhibits YAP via transcriptional and post-translational regulation

CONTEXT

Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumour cell growth by inducing cell cycle arrest. However, its underlying anticancer mechanism remains unclear.

OBJECTIVE

The effects of LAF on the Hippo-Yes-associated protein (YAP) signalling pathway, which plays an important role in cancer progression, were explored in this study.

MATERIALS AND METHODS

Cervical (HeLa), colorectal (SW480), breast (MDA-MB-231) and prostate (PC3) cancer cell lines were treated with LAF at different concentrations and different durations. BALB/c nude mice bearing colon xenografts were intravenously injected with vehicle, LAF (10 or 20 mg/kg) or paclitaxel (10 mg/kg) for 15 days. The expression and nuclear localisation of YAP were analysed using transcriptome sequencing, quantitative PCR, western blotting and immunofluorescence.

RESULTS

LAF suppressed the proliferation of HeLa, MDA-MB-231, SW480 and PC3 cells (IC₅₀ values of 41.5, 26.0, 45.3 and 42.9 μmol/L, respectively, at 72 h), and this was accompanied by significant downregulation in the expression of YAP and its downstream target genes at both the mRNA and protein levels. The expression of 14-3-3σ, a protein that causes YAP cytoplasmic retention and degradation, was remarkably increased, resulting in a decrease in YAP nuclear localisation. Knockdown of 14-3-3σ with small interfering RNA partially blocked LAF-induced YAP inhibition and anti-proliferation effects. In colon xenografts, treatment with LAF led to reduced YAP expression, increased tumour cell apoptosis and tumour growth inhibition.

CONCLUSION

LAF was shown to be an inhibitor of YAP. It exerts anticancer activity by inhibiting YAP at the transcriptional and post-translational levels.

YAP Promotes Cell Proliferation and Epithelium-Derived Cytokine Expression via NF-κB Pathway in Nasal Polyps

Background

Hippo-Yes-associated protein (YAP) pathway plays an important role in epithelial cell proliferation and inflammation development in chronic rhinosinusitis with nasal polyps (CRSwNP). However, the underlying mechanisms remain unclear.

Objective

This study intends to investigate the role of YAP and the nuclear factor kappa-B (NF-κB) pathway in cell proliferation and the expression of epithelium-derived cytokines in nasal polyps (NP).

Methods

The expression levels of YAP, TEA domain family member 1 (TEAD1), Ki-67, and NF-κB as well as interleukin (IL-) 33, IL-25 and thymic stromal lymphopoietin (TSLP) in sinonasal mucosa, primary nasal epithelial cells (NPECs), and human nasal epithelial RPMI 2650 cells were detected. NPECs were cultured and treated with verteporfin (VP), YAP shRNA or BAY 11–7082.

Results

The hippo pathway effector YAP, Ki-67, p65 NF-κB, and cyclin D1 were significantly increased in NP compared with control mucosa, which was accompanied by overexpression of IL-33, IL-25, and TSLP. Pharmaceutical inhibition of YAP by VP suppressed cell proliferation of RPMI 2650 cells by blocking cell cycle progression at G0/G1 without inducing obvious cell apoptosis. Furthermore, lentiviral transfection-mediated knockdown of hippo pathway activity reduced the expression of IL-33, IL-25, TSLP as well as p65 NF-κB in RPMI 2650 cells. Downregulation of NF-κB pathway with BAY 11–7082 in NPECs could decrease the mRNA level of TSLP, IL-33 and IL-25 accordingly.

Conclusion

Inhibition of hippo pathway suppressed nasal epithelial cell proliferation and declined the expression of epithelium-derived cytokines via the NF-κB pathway in NPECs.

Claudin-2 inhibits renal clear cell carcinoma progression by inhibiting YAP-activation

Background

Claudin-2 expression is upregulated in multiple cancers and promotes cancer malignancy. Remarkably, the regulation of claudin-2 expression in kidney cell lines contrasts its reported regulation in other organs. However, claudin-2 role in renal clear cell carcinoma (RCC) remains unknown despite its predominant expression in the proximal tubular epithelium (PTE), the site of RCC origin.

Methods

Publicly available and independent patient databases were examined for claudin-2 association with RCC. The novel protein function was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by Mass spectroscopy, immunoprecipitation and mutational studies, and functional evaluations.

Results

We show that the significant decrease in claudin-2 expression characterized PTE cells and Ex-vivo cultured mouse kidney subjected to dedifferentiation. Inhibition of claudin-2 was enough to induce mesenchymal plasticity and invasive mobility in these models. Further, a progressive loss of claudin-2 expression associated with the RCC progression and poor patient survival. Overexpression of claudin-2 in RCC-derived cancer cells inhibited tumorigenic abilities and xenograft tumor growth. These data supported a novel tumor-suppressive role of claudin-2 in RCC. Mechanistic insights further revealed that claudin-2 associates with YAP-protein and modulates its phosphorylation (S127) and nuclear expression. The tumor suppressive effects of claudin-2 expression were lost upon deletion of its PDZ-binding motif emphasizing the critical role of the PDZ-domain in claudin-2 interaction with YAP in regulating RCC malignancy.

Conclusions

Our results demonstrate a novel kidney specific tumor suppressive role for claudin-2 protein and further demonstrate that claudin-2 co-operates with the YAP signaling in regulating the RCC malignancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01870-5.

Context-dependent roles of YAP/TAZ in stem cell fates and cancer

Hippo effectors YAP and TAZ control cell fate and survival through various mechanisms, including transcriptional regulation of key genes. However, much of this research has been marked by conflicting results, as well as controversy over whether YAP and TAZ are redundant. A substantial portion of the discordance stems from their contradictory roles in stem cell self-renewal vs. differentiation and cancer cell survival vs. apoptosis. In this review, we present an overview of the multiple context-dependent functions of YAP and TAZ in regulating cell fate decisions in stem cells and organoids, as well as their mechanisms of controlling programmed cell death pathways in cancer.

6-Gingerol suppresses tumor cell metastasis by increasing YAPser127 phosphorylation in renal cell carcinoma

According to the World Health Organization, the incidence and mortality rates of renal cell carcinoma (RCC) are rapidly increasing worldwide. Serious side effects caused by immune therapy and resistance to targeted drug therapy are urgent clinical problems facing kidney treatment. There is increasing global interest in developing natural products with a reduced number of side effects as adjunctive therapeutic options for RCC. Ginger is a spice and herbal remedy used worldwide, and 6-gingerol is a major pharmacologically active ingredient in ginger. In our study, we found that 6-gingerol suppressed RCC cell migration and metastasis in vitro and in vivo. Moreover, reduction in MMP2, Slug, and Vimentin protein levels was observed following 6-gingerol treatment of 786-O and ACHN cells. Furthermore, we revealed the mechanisms underlying the ability of 6-gingerol to inhibit RCC cell migration and metastasis. 6-Gingerol increased yes-associated protein (YAP)ser127 phosphorylation and reduced YAP levels in cell nuclei. We also used a series of loss-of-function and gain-of-function experiments to support our results. Western blot results showed that MMP2, Slug, and Vimentin protein expression was downregulated in YAP-silenced cells and upregulated in YAP-overexpressing cells. Transwell data demonstrated that YAP suppressed RCC migration ability. Immunofluorescence images showed that 6-gingerol decreased YAP levels, leading to disordered F-actin and a reduction in cell lamellipodia. Overall, our results indicated that 6-gingerol is a potential antimetastatic compound for use in kidney therapy.

The natural extract degalactotigonin exerts antitumor effects on renal cell carcinoma cells through repressing YAP

Background

The pervasive progression of renal cell carcinoma (RCC) after treatment demands more effective drugs with few side effects. In the present study, we determined whether degalactotigonin (DGT) extracted from Solanum nigrum L. could exert antitumoral effects on RCC and examined the related molecular mechanisms.

Methods

The effects of DGT on RCC cells were assessed by cell counting kit-8 (CCK-8) assay, flow cytometry, invasion and migration assays and subcutaneous tumor xenograft experiments in nude mice. The related molecular mechanisms were delineated by RNA sequencing (RNA-seq), real-time polymerase chain reaction (PCR), western blotting, coimmunoprecipitation (co-IP) and plasmid transfection.

Results

DGT induced apoptosis and suppressed the proliferation, invasion, migration, and tumorigenicity of RCC cells. Mechanistically, yes-associated protein (YAP) signaling was inactivated, and the expression of YAP and its target genes was reduced in degalactotigonin-treated RCC cells. Additionally, DGT activated phosphorylated large tumor suppressor 1/2 (p-LATS1/2) to phosphorylate YAP, which increased YAP retention in the cytoplasm but decreased the amount of YAP that entered the nuclei of RCC cells. Moreover, DGT impaired the increased aggressive features of RCC cells induced by YAP overexpression.

Conclusions

DGT is an effective therapeutic agent, which facilitates the apoptosis and inhibits the proliferation, invasion, migration, and tumorigenicity of RCC cells in a YAP-dependent manner.

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.

Long non-coding RNA PCAT1 drives clear cell renal cell carcinoma by upregulating YAP via sponging miR-656 and miR-539

Clear cell renal cell carcinoma (ccRCC) is the most common RCC subtype with high metastasis, poor prognosis and conventional chemotherapy resistance. Prostate cancer associated transcript 1 (PCAT1) is an important lncRNA that was reported to be involved in cell proliferation, migration and invasion of several types of cancer cells. However, its role in ccRCC is still undetermined. This study found that PCAT1 levels were elevated in ccRCC tumors as well as several ccRCC cells, and knockdown of PCAT1 with siRNA (si-PCAT1) alleviated cell proliferation, migration and invasion of Caki-2 and ACHN cells. With bioinformatics analysis, dual-luciferase reported assay, RNA pull-down assay and Spearman's correlation analysis, we demonstrated that PCAT1 acted as a sponge for miR-656 and miR-539. Moreover, we found dual competitive interaction of miR-656/539 with PCAT1 and yes-associated protein (YAP), resulting in the identification of PCAT1-miR-656/539-YAP axis in Caki-2 and ACHN cells. With CCK-8 assay and transwell assay, miR-656/539 inhibitor or YAP overexpression could alleviate the effects of si-PCAT1 on the proliferation, migration and invasion of Caki-2 and ACHN cells. Our data indicated that PCAT1 promotes proliferation, migration and invasion of ccRCC cells by upregulating YAP via sponging miR-656 and miR-539. Taken together, this study provided a novel therapeutic target for ccRCC treatment.

Elucidation of WW domain ligand binding specificities in the Hippo pathway reveals STXBP4 as YAP inhibitor

The Hippo pathway, which plays a critical role in organ size control and cancer, features numerous WW domain-based protein-protein interactions. However, ~100 WW domains and 2,000 PY motif-containing peptide ligands are found in the human proteome, raising a "WW-PY" binding specificity issue in the Hippo pathway. In this study, we have established the WW domain binding specificity for Hippo pathway components and uncovered a unique amino acid sequence required for it. By using this criterion, we have identified a WW domain-containing protein, STXBP4, as a negative regulator of YAP. Mechanistically, STXBP4 assembles a protein complex comprising α-catenin and a group of Hippo PY motif-containing components/regulators to inhibit YAP, a process that is regulated by actin cytoskeleton tension. Interestingly, STXBP4 is a potential tumor suppressor for human kidney cancer, whose downregulation is correlated with YAP activation in clear cell renal cell carcinoma. Taken together, our study not only elucidates the WW domain binding specificity for the Hippo pathway, but also reveals STXBP4 as a player in actin cytoskeleton tension-mediated Hippo pathway regulation.

YAP Promotes VEGFA Expression and Tumor Angiogenesis Though Gli2 in Human Renal Cell Carcinoma

BACKGROUND

High vascularization is a major characteristic of renal cell carcinoma (RCC). Thus, exploration of molecules promoting the tumor vascularization in RCC is urgent. Yes-associated Protein (YAP) is an oncogene in many cancer types, and high YAP expression was correlated with worse overall survival of RCC patients according to The Cancer Genome Atlas (TCGA) database. However, whether YAP promotes tumor angiogenesis of RCC is still unknown.

METHODS

Western blotting assay, real-time Quantitive PCR analysis, and ELISA assay were used to detect the related gene expression. The function of YAP on tumor angiogenesis was investigated by HUVEC recruitment, tube formation, and rabbit cornea assay. The clinical relevance of several genes was analyzed in a public database.

RESULTS

knockdown of YAP decreased RCC cell-inducing HUVEC recruitment and tube formation. Moreover, tumor angiogenesis ability of 786-O cells was crippled by YAP knockdown in vivo. In addition, the expression of Vascular endothelial growth factors A (VEGFA) was positively correlated with YAP expression in RCC tumor tissues, and YAP promoted expression and secretion of VEGFA in RCC cells. Mechanistically, GLI family zinc finger 2 (Gli2) knockdown in RCC cells reduced both basic and YAP-induced VEGFA expression, HUVECs recruitment, and tube formation, indicating that Gli2 is necessary for YAP to promote expression of VEGFA.

CONCLUSION

Taken together, our results demonstrate that YAP/Gli2 promotes VEGFA expression and tumor angiogenesis in RCC cells, which could provide novel therapeutic targets in RCC treatment.

Knockdown of YAP inhibits growth in Hep-2 laryngeal cancer cells via epithelial-mesenchymal transition and the Wnt/β-catenin pathway

BACKGROUND

Yes-associated protein (YAP) plays a crucial role in tumour development and it is the main effector of the Hippo signalling pathway. However, the mechanism underlying YAP downregulation in laryngeal cancer is still unclear. In our previous study, we found that YAP, compared with adjacent tissues, was expressed higher in laryngeal cancer and was also closely associated with histological differentiation, TNM stage and poor prognosis.

METHODS

In this study, we attempted to determine whether silenced YAP could downregulate human laryngeal carcinoma Hep-2 cells progression. YAP was downregulated in Hep-2 cells by shRNA, and the malignant ability of Hep-2 was assessed in vitro and in vivo.

RESULTS

In vitro, CCK-8, colony formation and wound healing assays showed that downregulation of YAP significantly reduced the rates of proliferation, migration, and invasion in Hep-2 cells. Downregulation of YAP distinctly induced G2/M cycle arrest and increased the rate of apoptosis. Accordingly, western blot assay suggested that the expression of DKK1, vimentin and β-catenin was significantly decreased after YAP downregulated treatment, thereby indicating that YAP mediated the EMT programme and the Wnt/β-catenin signalling pathway in carcinoma of the larynx. Furthermore, silencing of YAP suppressed Hep-2 cell tumourigenesis and metastasis in vivo.

CONCLUSION

In summary, our findings demonstrated the proliferation of YAP downregulation and the invasion of Hep-2 cells via downregulating the Wnt/β-catenin pathway in vitro and in vivo, suggesting that YAP may provide a potential therapeutic strategy for the treatment of laryngeal cancer.

CBX2 Regulates Proliferation and Apoptosis via the Phosphorylation of YAP in Hepatocellular Carcinoma

Chromobox 2 (CBX2), a chromobox family protein, is a crucial component of the polycomb group complex: polycomb repressive complex 1 (PRC1). Research on CBX2 as an oncogene has been published in recent years. However, the connection between CBX2 and hepatocellular carcinoma (HCC) has not been studied. In this article, based on the results of immunohistochemical (IHC) staining of HCC and adjacent liver tissue microarrays, we found that high CBX2 expression is associated with poor prognosis in HCC patients. The results of a CCK8 assay, a clonogenic survival assay and a nude mouse tumorigenicity assay showed that knockdown of CBX2 inhibited the proliferation of HCC cells. According to the results of Annexin V-FITC/propidium iodide (PI) staining-based fluorescence activated cell sorting (FACS) analysis, knockdown of CBX2 increased HCC cell apoptosis. Furthermore, the RNA-seq results revealed that knockdown of CBX2 inhibited the expression of WTIP, which is an inhibitor of the Hippo pathway. We used western blotting to validate the mechanism and discovered that knockdown of CBX2 increased the phosphorylation of YAP, which explains why knockdown of CBX2 inhibits proliferation and increases apoptosis in HCC cells. In conclusion, CBX2 could be a potential target for HCC anticancer treatment.

Analysis of the role of the Hippo pathway in cancer

Cancer is a serious health issue in the world due to a large body of cancer-related human deaths, and there is no current treatment available to efficiently treat the disease as the tumor is often diagnosed at a serious stage. Moreover, Cancer cells are often resistant to chemotherapy, radiotherapy, and molecular-targeted therapy. Upon further knowledge of mechanisms of tumorigenesis, aggressiveness, metastasis, and resistance to treatments, it is necessary to detect the disease at an earlier stage and for a better response to therapy. The hippo pathway possesses the unique capacity to lead to tumorigenesis. Mutations and altered expression of its core components (MST1/2, LATS1/2, YAP and TAZ) promote the migration, invasion, malignancy of cancer cells. The biological significance and deregulation of it have received a large body of interests in the past few years. Further understanding of hippo pathway will be responsible for cancer treatment. In this review, we try to discover the function of hippo pathway in different diversity of cancers, and discuss how Hippo pathway contributes to other cellular signaling pathways. Also, we try to describe how microRNAs, circRNAs, and ZNFs regulate hippo pathway in the process of cancer. It is necessary to find new therapy strategies for cancer.

Knockdown of the Hippo transducer YAP reduces proliferation and promotes apoptosis in the Jurkat leukemia cell

Leukemia and lymphoma are common hematological malignancies in children and young adults, which pose a tremendous threat to the survival of these young patients worldwide, despite availability of various effective treatments. The Hippo pathway is a novel-signaling pathway that regulates organ size, cell proliferation, apoptosis and tumorigenesis. The chief component of this pathway is the transducer yes-associated protein (YAP) which is over-expressed in numerous categories of tumors. However, little is known about the effect of YAP in hematological malignancies. In the present study, YAP expression was screened in several leukemia and lymphoma cell lines, and high YAP expression was demonstrated in Jurkat cells. To further unravel its effect on the biological behavior of Jurkat cells, lentivirus transduced short hairpin RNA (shRNA) technique was used to silence YAP. As expected, the YAP-specific shRNA dramatically inhibited YAP expression at the mRNA and protein levels. Reduced leukemia cell proliferation and increased cell apoptosis were demonstrated in YAP knockdown Jurkat cells. It was also demonstrated that YAP knockdown resulted in deregulated expression of a cluster of downstream genes crucial to cell proliferation or apoptosis, including protein kinase B, B-cell lymphoma 2 (BCL2) and BCL2 like protein 1. Consequently, the results of the present study established that suppression of YAP expression serves an important role in Jurkat cell proliferation and apoptosis, which may serve as a potential therapeutic target.

Long noncoding RNA TUG1 promotes cell proliferation and migration of renal cell carcinoma via regulation of YAP

OBJECTIVES

Recently, long noncoding RNAs (lncRNAs) have captured much attention for their important roles in human diseases. Deregulation of lncRNA taurine-upregulated gene 1 (TUG1) has been reported to regulate cancer progression in many cancer types. However, how TUG1 contributes to renal cell carcinoma (RCC) remains elusive; we were eager to resolve the questions.

METHODS

Tumor tissues and the matched adjacent normal tissues were collected from patients with RCC. Messenger RNA (mRNA) levels of TUG1, yes-associated protein (YAP), and microRNA (miR)-9 levels were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The regulation of YAP by TUG1 was investigated using Western blot analysis, RT-qPCR, and immunofluorescence. The oncogenic roles of TUG1 and YAP were studied using a cell proliferation assay and a wound healing assay. The interaction of TUG1-miR-9-YAP was analyzed in RCC cell lines.

RESULTS

In the current study, we observed a positive correlation between TUG1 expression and YAP expression in RCC using the Gene Expression Omnibus database and tumor tissues collected from 58 patients with RCC. The TUG1 elevation enhanced YAP expression but did not alter the Hippo-signaling pathway activity or YAP protein distribution in cells. In addition, we found that TUG1 could bind to miR-9; therefore, TUG1 could positively control YAP expression via downregulation of miR-9 level. Furthermore, we observed that inhibition of cell proliferation and cell migration induced by TUG1 silencing could be reversed by overexpression of YAP in RCC cell lines.

CONCLUSIONS

Our findings indicated a pivotal role of TUG1 in driving RCC progression via regulation of miR-9/YAP, suggesting a potential therapeutic targeting role of TUG1 in RCC.

Role of YAP in lung cancer resistance to cisplatin

Yes-associated protein (YAP) serves a critical role in the initiation and progression of a variety of types of cancer via modulating the expression of genes involved in cell proliferation and the downregulation of apoptosis. Recent studies have suggested that YAP is responsible for the development of drug resistance and cancer metastasis and recurrence. However, the association between YAP and chemoresistance in lung cancer, particularly in lung cancer stem cells (LCSCs) remains largely unknown. In the current study, lung cancer cell spheres were established using the A549 cell line, which demonstrated stem cell properties. It was revealed that YAP was overexpressed in lung cancer spheres compared with normal A549 adherent cells and was associated with enhanced cisplatin (CDDP) resistance. Knockdown of YAP effectively sensitized the adherent A549 and tumor spheres to CDDP treatment and resulted in enhanced cell death. These results suggest that YAP serves a critical role in LCSCs drug resistance and YAP targeting could become a promising adjuvant to current the chemotherapy for lung cancer.

REGγ deficiency suppresses tumor progression via stabilizing CK1ε in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common malignant disease of kidney in adults. The proteasome activator REGγ was previously reported to promote the degradation of multiple important regulatory proteins and involved in the progression and development of numerous human cancers. Here, we first reported that REGγ was upregulated in RCC and its upregulation was correlated with a poor prognosis in RCC patients. REGγ depletion obviously suppressed RCC cells proliferation in vitro and in vivo. Notably, casein kinase 1ε (CK1ε) was identified as a novel target of REGγ and knockdown of CK1ε effectively abolished the effect of REGγ depletion on RCC cells growth. Importantly, we also observed that REGγ depletion activated Hippo signaling pathway via stabilizing CK1ε in RCC, indicating the cross-talk between REGγ/CK1ε axis and Hippo pathway during RCC development. In conclusion, our findings suggested that REGγ played a pivotal role in the development of RCC and maybe helpful to identify new therapeutic strategies in the treatment of RCC.

Yes-associated protein and WW-containing transcription regulator 1 regulate the expression of sex-determining genes in Sertoli cells, but their inactivation does not cause sex reversal

Yes-associated protein (YAP) and WW-containing transcription regulator 1 (WWTR1) are two functionally redundant transcriptional regulators that are downstream effectors of the Hippo signaling pathway, and that act as major regulators of cell growth and differentiation. To elucidate their role in Sertoli cells, primary Sertoli cell culture from Yapflox/flox; Wwtr1flox/flox animals were infected with a Cre recombinase-expressing adenovirus. Concomitant inactivation of Yap and Wwtr1 resulted in a decrease in the mRNA levels of the male sex differentiation genes Dhh, Dmrt1, Sox9, and Wt1, whereas those of genes involved in female differentiation (Wnt4, Rspo1, and Foxl2) were induced. SOX9, FOXL2, and WNT4 proteins were regulated in the same manner as their mRNAs in response to loss of YAP and WWTR1. To further characterize the role of YAP and WWTR1 in Sertoli cells, we generated a mouse model (Yapflox/flox; Wwtr1flox/flox; Amhcre/+) in which Yap and Wwtr1 were conditionally deleted in Sertoli cells. An increase in the number of apoptotic cells was observed in the seminiferous tubules of 4 dpp mutant mice, leading to a reduction in testis weights and a decrease in the number of Sertoli cells in adult animals. Gene expression analyses of testes from 4 dpp Yapflox/flox; Wwtr1flox/flox; Amhcre/+ mice showed that Sertoli cell differentiation is initially altered, as Dhh, Dmrt1, and Sox9 mRNA levels were downregulated, whereas Wnt4 mRNA levels were increased. However, expression of these genes was not changed in older animals. Together, these results suggest a novel role of the Hippo signaling pathway in the mechanisms of sex differentiation.

The Immunoexpression of YAP1 and LATS1 Proteins in Clear Cell Renal Cell Carcinoma: Impact on Patients' Survival

The aim of the study was to determine by immunohistochemistry cellular localization and immunoreactivity levels of YAP1 and LATS1 proteins in paired sections of tumor and unchanged renal tissues of 54 clear cell renal cell carcinoma (ccRCC) patients. Associations between clinical-pathological and overall survival (OS; median follow-up was 40.6 months) data of patients and YAP1 and LATS1 immunoreactivity were analyzed by uni- and multivariate Cox regression model and log-rank test. YAP1 immunoreactivity was found in the nuclei of tumor cells in 64.8% of ccRCC patients, whereas only 24.1% of tumors revealed cytoplasmic YAP1 expression. LATS1 immunoexpression was observed only in the cytoplasm of tumor cells in 59.3% of patients. LATS1 immunoreactivity in cancer cells negatively correlated with the size of primary tumor. The overall YAP1 immunoreactivity did not correlate with clinical-pathological data of patients. However, the subgroup of ccRCC patients who presented with cytoplasmic YAP1 immunoexpression had significantly shorter OS (median = 26.8 months) than patients without cytoplasmic YAP1 expression (median undefined). Multivariate Cox analysis revealed that increased cytoplasmic YAP1 (HR = 4.53) and decreased LATS1 immunoreactivity levels (HR = 0.90) were associated with worse prognosis, being independent prognostic factors. These results suggest that YAP1 and LATS1 can be considered as new prognostic factors in ccRCC.

YAP1 enhances cell proliferation, migration, and invasion of gastric cancer in vitro and in vivo

Yes-associated protein 1 (YAP1) plays an important role in the development of carcinomas such as breast, colorectal, and gastric (GC) cancers, but the role of YAP1 in GC has not been investigated comprehensively. The present study strongly suggests that YAP1 and P62 were significantly up-regulated in GC specimens, compared with normal gastric mucosa. In addition, the YAP1^high P62^high expression was independently associated with poor prognosis in GC (hazard ratio: 1.334, 95% confidence interval: 1.045–1.704, P = 0.021). Stable YAP1 silencing inhibited the proliferation, migration, and invasion of BGC-823 GC cells in vitro and inhibited the growth of xenograft tumor and hematogenous metastasis of BGC-823 GC cells in vivo. The mechanism was associated with inhibited extracellular signal-regulated kinases (ERK)1/2 phosphorylation, elevated E-cadherin protein expression and decreased vimentin protein expression, down-regulated β-catenin protein expression and elevated α-catenin protein expression, and down-regulated long non-coding RNA (lncRNA) expressions including HOX transcript antisense RNA (HOTAIR), H19, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), human large tumor suppressor-2 (LATS2)-AS1-001, and LATS2. YAP1 over-expression promoted the proliferation, migration, and invasion of human immortalized normal gastric mucosa GES-1 cells in vitro by reversing the above signal molecules. Subcutaneous inoculation of GES-1 cells and YAP1-over-expressing GES-1 cells into nude mice did not generate tumors. We successfully established the xenograft tumor models using MKN-45 GC cells, but immunochemistry showed that there was no YAP1 expression in MKN-45 cells. These results suggest that YAP1 is not a direct factor affecting tumor formation, but could accelerate tumor growth and metastasis. Collectively, this study highlights an important role for YAP1 as a promoter of GC growth and metastasis, and suggests that YAP1 could possibly be a potential treatment target for GC.

Targeted Disruption of YAP and TAZ Impairs the Maintenance of the Adrenal Cortex

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are functionally redundant transcriptional regulators that are downstream effectors of the Hippo signaling pathway. They act as major regulators of stem cell maintenance, cell growth, and differentiation. To characterize their roles in the adrenal cortex, we generated a mouse model in which Yap and Taz were conditionally deleted in steroidogenic cells (Yapflox/flox;Tazflox/flox;Nr5a1cre/+). Male Yapflox/flox;Tazflox/flox;Nr5a1cre/+ mice were characterized by an age-dependent degeneration of the adrenal cortex associated with an increase in apoptosis and a progressive reduction in the expression levels of steroidogenic genes. Evaluation of the expression levels of stem and progenitor cell population markers in the adrenal glands of Yapflox/flox;Tazflox/flox;Nr5a1cre/+ mice also showed the downregulation of sonic hedgehog (Shh), a marker of the subcapsular progenitor cell population. Gross degenerative changes were not observed in the adrenal glands of Yapflox/flox;Tazflox/flox;Nr5a1cre/+ females, although steroidogenic capacity and Shh expression were reduced, suggesting that mechanisms of adrenocortical maintenance are sex specific. These results define a crucial role for YAP and TAZ in the maintenance of the postnatal adrenal cortex.

Hippo vs. Crab: tissue-specific functions of the mammalian Hippo pathway

The Hippo signaling pathway is a vital suppressor of tumorigenesis that is often inactivated in human cancers. In normal cells, the Hippo pathway is triggered by external forces such as cell crowding, or changes to the extracellular matrix or cell polarity. Once activated, Hippo signaling down-regulates transcription supported by the paralogous cofactors YAP1 and TAZ. The Hippo pathway's functions in normal and cancer biology have been dissected by studies of mutant mice with null or conditional tissue-specific mutations of Hippo signaling elements. In this review, we attempt to systematically summarize results that have been gleaned from detailed in vivo characterizations of these mutants. Our goal is to describe the physiological roles of Hippo signaling in several normal organ systems, as well as to emphasize how disruption of the Hippo pathway, and particularly hyperactivation of YAP1/TAZ, can be oncogenic.

Effect of YAP Inhibition on Human Leukemia HL-60 Cells

Background: Yes-associated protein (YAP), the nuclear effector of the Hippo pathway, is a candidate oncoprotein and participates in the progression of various malignancies. However, few reports have examined the effect of YAP inhibition in human leukemia HL-60 cells. Methods: We examined the effects of YAP knockdown or inhibition using short hairpin RNA (shRNA) or verteporfin (VP), respectively. Western blot assays were used to determine the expression levels of YAP, Survivin, cyclinD1, PARP, Bcl-2, and Bax. Cell proliferation was assessed using the cell counting kit (CCK-8) assay. Cell cycle progression and apoptosis were evaluated by flow cytometry, and apoptotic cell morphology was observed by Hoechst 33342 staining. Results: Knockdown or inhibition of YAP led to cell cycle arrest at the G0/G1 phase and increased apoptosis, inhibited cell proliferation, increased levels of Bax and cleaved PARP, and decreased levels of PARP, Bcl-2, Survivin, and cyclinD1. Moreover, Hoechst 33342 staining revealed increased cell nuclear fragmentation. Conclusion: Collectively, these results show that inhibition of YAP inhibits proliferation and induces apoptosis in HL-60 cells. Therefore, a novel treatment regime involving genetic or pharmacological inhibition of YAP could be established for acute promyelocytic leukemia.

Hippo signaling in the kidney: the good and the bad

The Hippo signaling pathway is an evolutionarily conserved kinase cascade, playing multiple roles in embryonic development that controls organ size, cell proliferation, and apoptosis. At the center of this network lie the Hippo kinase target and downstream pathway effector Yes-associated protein (YAP) and its paralog TAZ. In its phosphorylated form, cytoplasmic YAP is sequestered in an inactive state. When it is dephosphorylated, YAP, a potent oncogene, is activated and relocates to the nucleus to interact with a number of transcription factors and signaling regulators that promote cell growth, differentiation, and survival. The identification of YAP activation in human cancers has made it an attractive target for chemotherapeutic drug development. Little is known to date about the function of the Hippo pathway in the kidney, but that is rapidly changing. Recent studies have shed light on the role of Hippo-YAP signaling in glomerular and lower urinary tract embryonic development, maintenance of podocyte homeostasis, the integrity of the glomerular filtration barrier, regulation of renal tubular cyst growth, renal epithelial injury in diabetes, and renal fibrogenesis. This review summarizes the current knowledge of the Hippo-YAP signaling axis in the kidney under normal and disease conditions.

Disease implications of the Hippo/YAP pathway

The Hippo signaling pathway is important for controlling organ size and tissue homeostasis. Originally identified in Drosophila melanogaster, the core components of the Hippo pathway are highly conserved in mammals. The Hippo pathway can be modulated by a wide range of stimuli, including G protein-coupled receptor (GPCR) signaling, changes in the actin cytoskeleton, cell-cell contact, and cell polarity. When activated, the Hippo pathway functions as a tumor suppressor to limit cell growth. However, dysregulation by genetic inactivation of core pathway components or amplification or gene fusion of its downstream effectors results in increased cell proliferation and decreased apoptosis and differentiation. Unsurprisingly, this can lead to tissue overgrowth, tumorigenesis, and many other diseases.

Role of Yes-associated protein 1 in gliomas: pathologic and therapeutic aspects

The activation of proline-rich phosphoprotein Yes-associated protein 1 (YAP1) possesses a possible link between stem/progenitor cells, organ size, and cancer. YAP1 has been indicated as an oncoprotein, and overexpression of YAP1 is reported in many human brain tumors, including infiltrating gliomas. During normal brain development, the neurofibromatosis 2 (NF2) protein suppresses YAP1 activity in neural progenitor cells to promote guidepost cell differentiation, but loss of NF2 causes elevating YAP1 activity in midline neural progenitors, which disrupts guidepost formation. Overexpression of endogenous CD44 (cancer stem cell marker) promotes phosphorylation/inactivation of NF2, and upregulates YAP1 expression and leads to cancer cell resistance in glioblastoma. The hippo pathway is also related to the YAP1 action. However, the mechanism of YAP1 action in glioma is still far from clear understanding. Advances in clinical management based on an improved understanding of the function of YAP1 may help to serve as a molecular target in glioma therapeutics. Knockdown of YAP1 by shRNA technology has been shown to reduce glioma in vitro; however, clinical implications are still under investigation. YAP1 can be used as a diagnostic marker for gliomas to monitor the disease status and may help to evaluate its treatment effects. More functional experiments are needed to support the direct roles of YAP1 on gliomas at molecular and cellular levels.

Parameters of dynamic contrast-enhanced MRI as imaging markers for angiogenesis and proliferation in human breast cancer

Background

Breast cancer is the most common malignancy and the leading cause of cancer death in women worldwide; however, early diagnosis has been difficult due to its complex pathological structure. This study evaluated the value of morphological examination in conjunction with dynamic contrast-enhanced MRI (DCE-MRI) for more precise diagnosis of breast cancer, as well as their correlation with angiogenesis and proliferation biomarkers.

Material/Methods

DCE-MRI parameters (including K^trans: volume transfer coefficient reflecting vascular permeability, K_ep: flux rate constant, V_e: extracellular volume ratio reflecting vascular permeability, and ADC: apparent diffusion coefficient) were obtained from 124 patients with breast cancer (124 lesions). Microvessel density (MVD) was evaluated by the immunohistochemical analysis of tumor vessels for CD31 and CD105 expression. The proliferation was assessed by analyzing Ki67.

Results

K^trans values were in the order of: malignant lesions > benign lesions > normal glands. Similar results were observed for K_ep. The opposite changes were seen with V_e. K^trans and K_ep values were significantly higher in invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS) than in mammary ductal dysplasia (MDD; ANOVA followed by Dunnett’s test). In sharp contrast, ADC values were lower in IDC and DCIS than in MDD, and V_e was not significantly different among the three groups. The data from MIP (maximum intensity projection) showed that benign breast lesions had no or only one blood vessel, whereas malignant lesions had two or more blood vessels. In addition, expression of CD105 and Ki67, the commonly recognized markers for angiogenesis and proliferation, respectively, were closely correlated with MRI parameters as revealed by Pearson analysis.

Conclusions

Determination of K^trans, K_ep and ADC values permits estimation of tumor angiogenesis and proliferation in breast cancer and DCE-MRI parameters can be used as imaging biomarkers to predict patient prognosis and the biologic aggressiveness of the tumor.