Hippo signaling mediates proliferation, invasiveness, and metastatic potential of clear cell renal cell carcinoma

Hyperactivated YAP1 is essential for sustainable progression of renal clear cell carcinoma

The most notable progress in renal clear cell carcinoma (ccRCC) in the past decades is the introduction of drugs targeting the VHL-HIF signaling pathway-associated angiogenesis. However, mechanisms underlying the development of VHL mutation-independent ccRCC are unclear. Here we provide evidence that the disrupted Hippo-YAP signaling contributes to the development of ccRCC independent of VHL alteration. We found that YAP1 and its primary target genes are frequently upregulated in ccRCC and the upregulation of these genes is associated with unfavorable patient outcomes. Research results derived from our in vitro and in vivo experimental models demonstrated that, under normoxic conditions, hyperactivated YAP1 drives the expression of FGFs to stimulate the proliferation of tumor and tumor-associated endothelial cells in an autocrine/paracrine manner. When rapidly growing cancer cells create a hypoxic environment, hyperactivated YAP1 in cancer cells induces the production of VEGF, which promotes the angiogenesis of tumor-associated endothelial cells, leading to improved tumor microenvironment and continuous tumor growth. Our study indicates that hyperactivated YAP1 is essential for maintaining ccRCC progression, and targeting the dual role of hyperactivated YAP1 represents a novel strategy to improve renal carcinoma therapy.

Transcription enhanced associate domain factor 1 (TEAD1) predicts liver regeneration outcome of ALPPS-treated patients

BACKGROUND

The two-stage surgical technique of associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) enables extensive liver resection and promotes future liver remnant regeneration (FLR), in part by inhibiting the Hippo signalling pathway. Its main effector, Yes-associated protein (YAP), has low intrinsic transcriptional activity and requires the transcription enhanced associated domain factor (TEAD) family members as cofactors for target gene transcription. We evaluated the intracellular localization and expression of TEAD1-4, hypothesized to regulate the activity of YAP and, consequently, liver regeneration.

METHODS

The intracellular localization of TEAD1-4 was characterized in tumor-free liver (TFL) tissue samples from 44 ALPPS patients obtained during the two stages of ALPPS surgery. Expression levels were correlated with clinical and pathological data as well as liver regeneration metrics.

RESULTS

TEAD family members are simultaneously expressed in individual hepatocytes and show relations with liver regeneration, clinical outcome and outcome parameters when comparing TFL tissue obtained at different stages of ALPPS surgery. Furthermore, differences in TEAD expression and localization within hepatocytes appeared to be independent of global factors.

CONCLUSION

TEAD1-4 expression correlates with liver regeneration outcomes. Specifically, cytoplasmic and nuclear expression scores of TEAD1 serve as predictive markers for clinical outcomes following ALPPS.

Tumor Cell Spatial Organization Directs EGFR/RAS/RAF Pathway Primary Therapy Resistance through YAP Signaling

Non-small cell lung cancers (NSCLC) harboring common mutations in EGFR and KRAS characteristically respond transiently to targeted therapies against those mutations, but invariably, tumors recur and progress. Resistance often emerges through mutations in the therapeutic target or activation of alternative signaling pathways. Mechanisms of acute tumor cell resistance to initial EGFR (EGFRi) or KRASG12C (G12Ci) pathway inhibition remain poorly understood. Our study reveals that acute response to EGFR/RAS/RAF-pathway inhibition is spatial and culture context specific. In vivo, EGFR mutant tumor xenografts shrink by > 90% following acute EGFRi therapy, and residual tumor cells are associated with dense stroma and have increased nuclear YAP. Interestingly, in vitro EGFRi induced cell cycle arrest in NSCLC cells grown in monolayer, while 3D spheroids preferentially die upon inhibitor treatment. We find differential YAP nuclear localization and activity, driven by the distinct culture conditions, as a common resistance mechanism for selective EGFR/KRAS/BRAF pathway therapies. Forced expression of the YAPS127A mutant partially protects cells from EGFR-mediated cell death in spheroid culture. These studies identify YAP activation in monolayer culture as a non-genetic mechanism of acute EGFR/KRAS/BRAF therapy resistance, highlighting that monolayer vs spheroid cell culture systems can model distinct stages of patient cancer progression.

The Hippo Signaling Pathway Manipulates Cellular Senescence

The Hippo pathway, a kinase cascade, coordinates with many intracellular signals and mediates the regulation of the activities of various downstream transcription factors and their coactivators to maintain homeostasis. Therefore, the aberrant activation of the Hippo pathway and its associated molecules imposes significant stress on tissues and cells, leading to cancer, immune disorders, and a number of diseases. Cellular senescence, the mechanism by which cells counteract stress, prevents cells from unnecessary damage and leads to sustained cell cycle arrest. It acts as a powerful defense mechanism against normal organ development and aging-related diseases. On the other hand, the accumulation of senescent cells without their proper removal contributes to the development or worsening of cancer and age-related diseases. A correlation was recently reported between the Hippo pathway and cellular senescence, which preserves tissue homeostasis. This review is the first to describe the close relationship between aging and the Hippo pathway, and provides insights into the mechanisms of aging and the development of age-related diseases. In addition, it describes advanced findings that may lead to the development of tissue regeneration therapies and drugs targeting rejuvenation.

Research progress of the Hippo signaling pathway in renal cell carcinoma

Objective

This review aimed to summarize the role of the Hippo signaling pathway in renal cell carcinoma (RCC), a urologic malignancy with subtle initial symptoms and high mortality rates due to metastatic RCC. The Hippo signaling pathway, which regulates tissue and organ sizes, plays a crucial role in RCC progression and metastasis. Understanding the involvement of the Hippo signaling pathway in RCC provides valuable insights for the development of targeted therapies and improved patient outcomes.

Methods

In this review, we explored the impact of the Hippo signaling pathway on RCC. Through an analysis of existing literature, we examined its role in RCC progression and metastasis. Additionally, we discussed potential therapeutic strategies targeting the Hippo pathway for inhibiting RCC cell growth and invasion. We also highlighted the importance of investigating interactions between the Hippo pathway and other signaling pathways such as Wnt, transforming growth factor-beta, and PI3K/AKT, which may uncover additional therapeutic targets.

Results

The Hippo signaling pathway has shown promise as a target for inhibiting RCC cell growth and invasion. Studies have demonstrated its dysregulation in RCC, with altered expression of key components such as yes-associated protein/transcriptional coactivator with PDZ-binding motif (YAP/TAZ). Targeting the Hippo pathway has been associated with suppressed tumor growth and metastasis in preclinical models of RCC. Furthermore, investigating crosstalk between the Hippo pathway and other signaling pathways has revealed potential synergistic effects that could be exploited for therapeutic interventions.

Conclusion

Understanding the role of the Hippo signaling pathway in RCC is of paramount importance. Elucidating its functions and molecular interactions contributes to RCC diagnosis, treatment, and the discovery of novel mechanisms. This knowledge informs the development of innovative therapeutic strategies and opens new avenues for research in RCC. Further investigations are warranted to fully comprehend the complex interplay between the Hippo pathway and other signaling pathways, ultimately leading to improved outcomes for RCC patients.

Hippo pathway effectors YAP, TAZ and TEAD are associated with EMT master regulators ZEB, Snail and with aggressive phenotype in phyllodes breast tumors

BACKGROUND

Phyllodes tumors (PTs) of the breast are uncommon fibroepithelial neoplasms that tend to recur locally and may have metastatic potential. Their pathogenesis is poorly understood. Hippo signaling pathway plays an essential role in organ size control, tumor suppression, tissue regeneration and stem cell self-renewal. Hippo signaling dysfunction has been implicated in cancer. Recent evidence suggests that there is cross-talk between the Hippo signaling key proteins YAP/TAZ and the epithelial-mesenchymal transition (EMT) master regulators Snail and ZEB. In this study we aimed to investigate the expression of Hippo signaling pathway components and EMT regulators in PTs, in relation to tumor grade.

METHODS

Expression of Hippo signaling effector proteins YAP, TAZ and their DNA binding partner TEAD was evaluated by immunohistochemistry in paraffin-embedded tissue specimens from 86 human phyllodes breast tumors (45 benign, 21 borderline, 20 malignant), in comparison with tumor grade and with the expression of EMT-related transcription factors ZEB and Snail.

RESULTS

Nuclear immunopositivity for YAP, TAZ and TEAD was detected in both stromal and epithelial cells in PTs and was significantly higher in high grade tumors. Interestingly, there was a significant correlation between the expression of YAP, TAZ, TEAD and the expression of ZEB and SNAIL.

CONCLUSIONS

Our results originally implicate Hippo signaling pathway in PTs pathogenesis and suggest that an interaction between Hippo signaling key components and EMT regulators may promote the malignant features of PTs.

Emerging Role of Hippo-YAP (Yes-Associated Protein)/TAZ (Transcriptional Coactivator with PDZ-Binding Motif) Pathway Dysregulation in Renal Cell Carcinoma Progression

Although Hippo-YAP/TAZ pathway involvement has been extensively studied in the development of certain cancers, the involvement of this cascade in kidney cancer progression is not well-established and, therefore, will be the focus of this review. Renal cell carcinoma (RCC), the most prevalent kidney tumor subtype, has a poor prognosis and a high mortality rate. Core Hippo signaling inactivation (e.g., LATS kinases) leads to the nuclear translocation of YAP/TAZ where they bind to co-transcriptional factors such as TEAD promoting transcription of genes which initiates various fibrotic and neoplastic diseases. Loss of expression of LATS1/2 kinase and activation of YAP/TAZ correlates with poor survival in RCC patients. Renal-specific ablation of LATS1 in mice leads to the spontaneous development of several subtypes of RCC in a YAP/TAZ-dependent manner. Genetic and pharmacological inactivation of YAP/TAZ reverses the oncogenic potential in LATS1-deficient mice, highlighting the therapeutic benefit of network targeting in RCC. Here, we explore the unique upstream controls and downstream consequences of the Hippo-YAP/TAZ pathway deregulation in renal cancer. This review critically evaluates the current literature on the role of the Hippo pathway in RCC progression and highlights the recent scientific evidence designating YAP/TAZ as novel therapeutic targets against kidney cancer.

Macrophage-Derived Nanosponges Adsorb Cytokines and Modulate Macrophage Polarization for Renal Cell Carcinoma Immunotherapy

Renal cell carcinoma (RCC) is a hot tumor infiltrated by large numbers of CD8+ T cells and is highly sensitive to immunotherapy. However, tumor-associated macrophages (TAMs), mainly M2 macrophages, tend to undermine the efficacy of immunotherapy and promote the progression of RCC. Here, macrophage-derived nanosponges are fabricated by M2 macrophage membrane-coated poly（lactic-co-glycolic acid）（PLGA）, which could chemotaxis to the CXC and CC chemokine subfamily-enriched RCC microenvironment via corresponding membrane chemokine receptors. Subsequently, the nanosponges act like cytokine decoys to adsorb and neutralize broad-spectrum immunosuppressive cytokines such as colony stimulating factor-1(CSF-1), transforming growth factor-β（TGF-β）, and Lnterleukin-10（IL-10）, thereby reversing the polarization of M2-TAMs toward the pro-inflammatory M1 phenotype, and enhancing the anti-tumor effect of CD8+ T cells. To further enhance the polarization reprogramming efficiency of TAMs, DSPE-PEG-M2pep is conjugated on the surface of macrophage-derived nanosponges for specific recognition of M2-TAMs, and the toll like receptors 7/8（TLR7/8） agonist, R848, is encapsulated in these nanosponges to induce M1 polarization, which result in significant efficacy against RCC. In addition, these nanosponges exhibit undetectable biotoxicity, making them suitable for clinical applications. In summary, a promising and facile strategy is provided for immunomodulatory therapies, which are expected to be used in the treatment of tumors, autoimmune diseases, and inflammatory diseases.

YAP represses the TEAD-NF-κB complex and inhibits the growth of clear cell renal cell carcinoma

The Hippo pathway is generally understood to inhibit tumor growth by phosphorylating the transcriptional cofactor YAP to sequester it to the cytoplasm and reduce the formation of YAP-TEAD transcriptional complexes. Aberrant activation of YAP occurs in various cancers. However, we found a tumor-suppressive function of YAP in clear cell renal cell carcinoma (ccRCC). Using cell cultures, xenografts, and patient-derived explant models, we found that the inhibition of upstream Hippo-pathway kinases MST1 and MST2 or expression of a constitutively active YAP mutant impeded ccRCC proliferation and decreased gene expression mediated by the transcription factor NF-κB. Mechanistically, the NF-κB subunit p65 bound to the transcriptional cofactor TEAD to facilitate NF-κB-target gene expression that promoted cell proliferation. However, by competing for TEAD, YAP disrupted its interaction with NF-κB and prompted the dissociation of p65 from target gene promoters, thereby inhibiting NF-κB transcriptional programs. This cross-talk between the Hippo and NF-κB pathways in ccRCC suggests that targeting the Hippo-YAP axis in an atypical manner-that is, by activating YAP-may be a strategy for slowing tumor growth in patients.

Comparative interactome analysis of α-arrestin families in human and Drosophila

The α-arrestins form a large family of evolutionally conserved modulators that control diverse signaling pathways, including both G-protein-coupled receptor (GPCR)-mediated and non-GPCR-mediated pathways, across eukaryotes. However, unlike β-arrestins, only a few α-arrestin targets and functions have been characterized. Here, using affinity purification and mass spectrometry, we constructed interactomes for 6 human and 12 Drosophila α-arrestins. The resulting high-confidence interactomes comprised 307 and 467 prey proteins in human and Drosophila, respectively. A comparative analysis of these interactomes predicted not only conserved binding partners, such as motor proteins, proteases, ubiquitin ligases, RNA splicing factors, and GTPase-activating proteins, but also those specific to mammals, such as histone modifiers and the subunits of V-type ATPase. Given the manifestation of the interaction between the human α-arrestin, TXNIP, and the histone-modifying enzymes, including HDAC2, we undertook a global analysis of transcription signals and chromatin structures that were affected by TXNIP knockdown. We found that TXNIP activated targets by blocking HDAC2 recruitment to targets, a result that was validated by chromatin immunoprecipitation assays. Additionally, the interactome for an uncharacterized human α-arrestin ARRDC5 uncovered multiple components in the V-type ATPase, which plays a key role in bone resorption by osteoclasts. Our study presents conserved and species-specific protein-protein interaction maps for α-arrestins, which provide a valuable resource for interrogating their cellular functions for both basic and clinical research.

ApoM suppresses kidney renal clear cell carcinoma growth and metastasis via the Hippo-YAP signaling pathway

Renal cell carcinoma is one of the most common malignancies worldwide, and kidney renal clear cell carcinoma (KIRC) is the most common histopathological type of renal cell carcinoma. However, the mechanism of KIRC progression remains poorly understood. Apolipoprotein M (ApoM) is a plasma apolipoprotein and a member of the lipid transport protein superfamily. Lipid metabolism is essential for tumor progression, and its related proteins can be used as therapeutic targets for tumors. ApoM influences the development of several cancers, but its relationship with KIRC remains unclear. In this study, we aimed to investigate the biological function of ApoM in KIRC and to reveal its potential molecular mechanisms. We found that ApoM expression was significantly reduced in KIRC and was strongly correlated with patient prognosis. ApoM overexpression significantly inhibited KIRC cell proliferation in vitro, suppressed the epithelial mesenchymal transition (EMT) of KIRC cells, and decreased their metastatic capacity. Additionally, the growth of KIRC cells was inhibited by ApoM overexpression in vivo. In addition, we found that overexpression of ApoM in KIRC attenuated Hippo-YAP protein expression and YAP stability and thus inhibited KIRC growth and progression. Therefore, ApoM may be a potential target for the treatment of KIRC.

Comprehensive analyses of A 12-metabolism-associated gene signature and its connection with tumor metastases in clear cell renal cell carcinoma

BACKGROUND

The outcomes of patients with clear cell renal cell carcinoma (ccRCC) were dreadful due to lethal local recurrence and distant metastases. Accumulating evidence suggested that ccRCC was considered a metabolic disease and metabolism-associated genes (MAGs) exerted essential functions in tumor metastases. Thus, this study intends to seek whether the dysregulated metabolism promotes ccRCC metastases and explores underlying mechanisms.

METHOD

Weighted gene co-expression network analysis (WGCNA) was employed based on 2131 MAGs to select genes mostly associated with ccRCC metastases for subsequent univariate Cox regression. On this basis, least absolute shrinkage and selection operator (LASSO) regression and multivariate Cox regression were employed to create a prognostic signature based on the cancer genome atlas kidney renal clear cell carcinoma (TCGA-KIRC) cohort. The prognostic signature was confirmed using E-MTAB-1980 and GSE22541 cohorts. Kaplan-Meier, receiver operating characteristic (ROC) curve, and univariate and multivariate Cox regression were applied to detect the predictability and independence of the signature in ccRCC patients. Functional enrichment analyses, immune cell infiltration examinations, and somatic variant investigations were employed to detect the biological roles of the signature.

RESULT

A 12-gene-metabolism-associated prognostic signature, termed the MAPS by our team, was constructed. According to the MAPS, patients were divided into low- and high-risk subgroups and high-risk patients displayed inferior outcomes. The MAPS was validated as an independent and reliable biomarker in ccRCC patients for forecasting the prognosis and progression of ccRCC patients. Functionally, the MAPS was closely associated with metabolism dysregulation, tumor metastases, and immune responses in which the high-risk tumors were in an immunosuppressive status. Besides, high-risk patients benefited more from immunotherapy and held a higher tumor mutation burden (TMB) than low-risk patients.

CONCLUSION

The 12-gene MAPS with prominent biological roles could independently and reliably forecast the outcomes of ccRCC patients, and provide clues to uncover the latent mechanism in which dysregulated metabolism controlled ccRCC metastases.

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.

Accurate detection of benign and malignant renal tumor subtypes with MethylBoostER: An epigenetic marker-driven learning framework

Current gold standard diagnostic strategies are unable to accurately differentiate malignant from benign small renal masses preoperatively; consequently, 20% of patients undergo unnecessary surgery. Devising a more confident presurgical diagnosis is key to improving treatment decision-making. We therefore developed MethylBoostER, a machine learning model leveraging DNA methylation data from 1228 tissue samples, to classify pathological subtypes of renal tumors (benign oncocytoma, clear cell, papillary, and chromophobe RCC) and normal kidney. The prediction accuracy in the testing set was 0.960, with class-wise ROC AUCs >0.988 for all classes. External validation was performed on >500 samples from four independent datasets, achieving AUCs >0.89 for all classes and average accuracies of 0.824, 0.703, 0.875, and 0.894 for the four datasets. Furthermore, consistent classification of multiregion samples (N = 185) from the same patient demonstrates that methylation heterogeneity does not limit model applicability. Following further clinical studies, MethylBoostER could facilitate a more confident presurgical diagnosis to guide treatment decision-making in the future.

YAP1 is essential for malignant mesothelioma tumor maintenance

Malignant pleural mesothelioma, a tumor arising from the membrane covering the lungs and the inner side of the ribs, is a cancer in which genetic alterations of genes encoding proteins that act on or are part of the Hippo-YAP1 signaling pathway are frequent. Dysfunctional Hippo signaling may result in aberrant activation of the transcriptional coactivator protein YAP1, which binds to and activates transcription factors of the TEAD family. Recent studies have associated elevated YAP1 protein activity with a poor prognosis of malignant mesothelioma and its resistance to current therapies, but its role in tumor maintenance is unclear. In this study, we investigate the dependence of malignant mesothelioma on YAP1 signaling to maintain fully established tumors in vivo. We show that downregulation of YAP1 in a dysfunctional Hippo genetic background results in the inhibition of YAP1/TEAD-dependent gene expression, the induction of apoptosis, and the inhibition of tumor cell growth in vitro. The conditional downregulation of YAP1 in established tumor xenografts leads to the inhibition of YAP1-dependent gene transcription and eventually tumor regression. This effect is only seen in the YAP1-activated MSTO-211H mesothelioma xenograft model, but not in the Hippo-independent HCT116 colon cancer xenograft model. Our data demonstrate that, in the context of a Hippo pathway mutated background, YAP1 activity alone is enough to maintain the growth of established tumors in vivo, thus validating the concept of inhibiting the activated YAP1-TEAD complex for the treatment of malignant pleural mesothelioma patients.

TEAD4 as an Oncogene and a Mitochondrial Modulator

TEAD4 (TEA Domain Transcription Factor 4) is well recognized as the DNA-anchor protein of YAP transcription complex, which is modulated by Hippo, a highly conserved pathway in Metazoa that controls organ size through regulating cell proliferation and apoptosis. To acquire full transcriptional activity, TEAD4 requires co-activator, YAP (Yes-associated protein) or its homolog TAZ (transcriptional coactivator with PDZ-binding motif) the signaling hub that relays the extracellular stimuli to the transcription of target genes. Growing evidence suggests that TEAD4 also exerts its function in a YAP-independent manner through other signal pathways. Although TEAD4 plays an essential role in determining that differentiation fate of the blastocyst, it also promotes tumorigenesis by enhancing metastasis, cancer stemness, and drug resistance. Upregulation of TEAD4 has been reported in several cancers, including colon cancer, gastric cancer, breast cancer, and prostate cancer and serves as a valuable prognostic marker. Recent studies show that TEAD4, but not other members of the TEAD family, engages in regulating mitochondrial dynamics and cell metabolism by modulating the expression of mitochondrial- and nuclear-encoded electron transport chain genes. TEAD4’s functions including oncogenic activities are tightly controlled by its subcellular localization. As a predominantly nuclear protein, its cytoplasmic translocation is triggered by several signals, such as osmotic stress, cell confluency, and arginine availability. Intriguingly, TEAD4 is also localized in mitochondria, although the translocation mechanism remains unclear. In this report, we describe the current understanding of TEAD4 as an oncogene, epigenetic regulator and mitochondrial modulator. The contributing mechanisms will be discussed.

Downregulation of miR-335 exhibited an oncogenic effect via promoting KDM3A/YAP1 networks in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common type of renal cancer affecting many people worldwide. Although the 5-year survival rate is 65% in localized disease, after metastasis, the survival rate is <10%. Emerging evidence has shown that microRNAs (miRNAs) play a crucial regulatory role in the progression of ccRCC. Here, we show that miR-335, an anti-onco-miRNA, is downregulation in tumor tissue and inhibited ccRCC cell proliferation, invasion, and migration. Our studies further identify the H3K9me1/2 histone demethylase KDM3A as a new miR-335-regulated gene. We show that KDM3A is overexpressed in ccRCC, and its upregulation contributes to the carcinogenesis and metastasis of ccRCC. Moreover, with the overexpression of KDM3A, YAP1 was increased and identified as a direct downstream target of KDM3A. Enrichment of KDM3A demethylase on YAP1 promoter was confirmed by CHIP-qPCR and YAP1 was also found involved in the cell growth and metastasis inhibitory of miR-335. Together, our study establishes a new miR-335/KDM3A/YAP1 regulation axis, which provided new insight and potential targeting of the metastasized ccRCC.

LncRNAs in the Regulation of Genes and Signaling Pathways through miRNA-Mediated and Other Mechanisms in Clear Cell Renal Cell Carcinoma

The fundamental novelty in the pathogenesis of renal cell carcinoma (RCC) was discovered as a result of the recent identification of the role of long non-coding RNAs (lncRNAs). Here, we discuss several mechanisms for the dysregulation of the expression of protein-coding genes initiated by lncRNAs in the most common and aggressive type of kidney cancer-clear cell RCC (ccRCC). A model of competitive endogenous RNA (ceRNA) is considered, in which lncRNA acts on genes through the lncRNA/miRNA/mRNA axis. For the most studied oncogenic lncRNAs, such as HOTAIR, MALAT1, and TUG1, several regulatory axes were identified in ccRCC, demonstrating a number of sites for various miRNAs. Interestingly, the LINC00973/miR-7109/Siglec-15 axis represents a novel agent that can suppress the immune response in patients with ccRCC, serving as a valuable target in addition to the PD1/PD-L1 pathway. Other mechanisms of action of lncRNAs in ccRCC, involving direct binding with proteins, mRNAs, and genes/DNA, are also considered. Our review briefly highlights methods by which various mechanisms of action of lncRNAs were verified. We pay special attention to protein targets and signaling pathways with which lncRNAs are associated in ccRCC. Thus, these new data on the different mechanisms of lncRNA functioning provide a novel basis for understanding the pathogenesis of ccRCC and the identification of new prognostic markers and targets for therapy.

Concurrent YAP/TAZ and SMAD signaling mediate vocal fold fibrosis

Vocal fold (VF) fibrosis is a major cause of intractable voice-related disability and reduced quality of life. Excision of fibrotic regions is suboptimal and associated with scar recurrence and/or further iatrogenic damage. Non-surgical interventions are limited, putatively related to limited insight regarding biochemical events underlying fibrosis, and downstream, the lack of therapeutic targets. YAP/TAZ integrates diverse cell signaling events and interacts with signaling pathways related to fibrosis, including the TGF-β/SMAD pathway. We investigated the expression of YAP/TAZ following vocal fold injury in vivo as well as the effects of TGF-β1 on YAP/TAZ activity in human vocal fold fibroblasts, fibroblast-myofibroblast transition, and TGF-β/SMAD signaling. Iatrogenic injury increased nuclear localization of YAP and TAZ in fibrotic rat vocal folds. In vitro, TGF-β1 activated YAP and TAZ in human VF fibroblasts, and inhibition of YAP/TAZ reversed TGF-β1-stimulated fibroplastic gene upregulation. Additionally, TGF-β1 induced localization of YAP and TAZ in close proximity to SMAD2/3, and nuclear accumulation of SMAD2/3 was inhibited by a YAP/TAZ inhibitor. Collectively, YAP and TAZ were synergistically activated with the TGF-β/SMAD pathway, and likely essential for the fibroplastic phenotypic shift in VF fibroblasts. Based on these data, YAP/TAZ may evolve as an attractive therapeutic target for VF fibrosis.

MITF Promotes Cell Growth, Migration and Invasion in Clear Cell Renal Cell Carcinoma by Activating the RhoA/YAP Signal Pathway

Microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix leucine zipper transcription factor involved in the lineage-specific regulation of melanocytes, osteoclasts and mast cells. MITF is also involved in the progression of melanomas and other carcinomas, including the liver, pancreas and lung. However, the role of MITF in clear cell renal cell carcinoma (ccRCC) is largely unknown. This study investigates the functional role of MITF in cancer and the molecular mechanism underlying disease progression in ccRCC. MITF knockdown inhibited cell proliferation and shifted the cell cycle in ccRCC cells. In addition, MITF knockdown reduced wound healing, cell migration and invasion compared with the controls. Conversely, MITF overexpression in SN12C and SNU482 cells increased cell migration and invasion. Overexpression of MITF activated the RhoA/YAP signaling pathway, which regulates cell proliferation and invasion, and increased YAP signaling promoted cell cycle-related protein expression. Additionally, tumor formation was impaired by MITF knockdown and enhanced by MITF overexpression in vivo. In summary, MITF expression was associated with aggressive tumor behavior, and increased the migratory and invasive capabilities of ccRCC cells. These effects were reversed by MITF suppression. These results suggest that MITF is a potential therapeutic target for the treatment of ccRCC.

A biomechanical switch regulates the transition towards homeostasis in oesophageal epithelium

Epithelial cells rapidly adapt their behaviour in response to increasing tissue demands. However, the processes that finely control these cell decisions remain largely unknown. The postnatal period covering the transition between early tissue expansion and the establishment of adult homeostasis provides a convenient model with which to explore this question. Here, we demonstrate that the onset of homeostasis in the epithelium of the mouse oesophagus is guided by the progressive build-up of mechanical strain at the organ level. Single-cell RNA sequencing and whole-organ stretching experiments revealed that the mechanical stress experienced by the growing oesophagus triggers the emergence of a bright Krüppel-like factor 4 (KLF4) committed basal population, which balances cell proliferation and marks the transition towards homeostasis in a yes-associated protein (YAP)-dependent manner. Our results point to a simple mechanism whereby mechanical changes experienced at the whole-tissue level are integrated with those sensed at the cellular level to control epithelial cell fate.

Intratumoral Fibrosis in Facilitating Renal Cancer Aggressiveness: Underlying Mechanisms and Promising Targets

Intratumoral fibrosis is a histologic manifestation of fibrotic tumor stroma. The interaction between cancer cells and fibrotic stroma is intricate and reciprocal, involving dysregulations from multiple biological processes. Different components of tumor stroma are implicated via distinct manners. In the kidney, intratumoral fibrosis is frequently observed in renal cell carcinoma (RCC). However, the underlying mechanisms remain largely unclear. In this review, we recapitulate evidence demonstrating how fibrotic stroma interacts with cancer cells and mechanisms shared between RCC tumorigenesis and renal fibrogenesis, providing promising targets for future studies.

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.

An overview of signaling pathways regulating YAP/TAZ activity

YAP and TAZ are ubiquitously expressed homologous proteins originally identified as penultimate effectors of the Hippo signaling pathway, which plays a key role in maintaining mammalian tissue/organ size. Presently, it is known that YAP/TAZ also interact with various non-Hippo signaling pathways, and have diverse roles in multiple biological processes, including cell proliferation, tissue regeneration, cell lineage fate determination, tumorigenesis, and mechanosensing. In this review, we first examine the various microenvironmental cues and signaling pathways that regulate YAP/TAZ activation, through the Hippo and non-Hippo signaling pathways. This is followed by a brief summary of the interactions of YAP/TAZ with TEAD1-4 and a diverse array of other non-TEAD transcription factors. Finally, we offer a critical perspective on how increasing knowledge of the regulatory mechanisms of YAP/TAZ signaling might open the door to novel therapeutic applications in the interrelated fields of biomaterials, tissue engineering, regenerative medicine and synthetic biology.

Inhibition of Yes-Associated Protein by Verteporfin Ameliorates Unilateral Ureteral Obstruction-Induced Renal Tubulointerstitial Inflammation and Fibrosis

Yes-associated protein (YAP) activation after acute ischemic kidney injury might be related to interstitial fibrosis and impaired renal tubular regeneration. Verteporfin (VP) is a photosensitizer used in photodynamic therapy to treat age-related macular degeneration. In cancer cells, VP inhibits TEA domain family member (TEAD)-YAP interactions without light stimulation. The protective role of VP in unilateral ureteral obstruction (UUO)-induced renal fibrosis and related mechanisms remains unclear. In this study, we investigate the protective effects of VP on UUO-induced renal tubulointerstitial inflammation and fibrosis and its regulation of the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway. We find that VP decreased the UUO-induced increase in tubular injury, inflammation, and extracellular matrix deposition in mice. VP also decreased myofibroblast activation and proliferation in UUO kidneys and NRK-49F cells by modulating Smad2 and Smad3 phosphorylation. Therefore, YAP inhibition might have beneficial effects on UUO-induced tubulointerstitial inflammation and fibrosis by regulating the TGF-β1/Smad signaling pathway.

LASP1 induces colorectal cancer proliferation and invasiveness through Hippo signaling and Nanog mediated EMT

The role of LIM and SH3 protein 1 (LASP1) in colorectal cancer (CRC) has been described in multiple studies, however, the underlying molecular mechanisms remained inclusive. In the present study, we performed immunohistochemistry (IHC) staining for LASP1 and found that LASP1 expression was higher in CRC tissue of advanced stage. Over-expressed (OE) LASP1 promoted proliferation, tumorigenesis and migration of CRC cell lines SW480 and SW620. Using the TCGA database, we identified Yes-associated protein (YAP1) was positively correlated with LASP1 expression in CRC patients. Introducing a novel YAP1 inhibitor CA3, we found that CA3 treatment inhibited LAPS1 OE SW480 and SW620 cells proliferation, colony number formation, invasion and migration. Further mechanistic experiments showed that Nanog, a stem cell marker, was up-regulated in LASP1 OE cells but suppressed by CA3 treatment. Chromatin immunoprecipitation (CHIP) and luciferase reporter assay revealed that YAP1 can directly target the promoter region of Nanog and enhance its activity. LASP1 accelerated CRC migration through targeting YAP1-mediated vimentin and E-cadherin expression. Finally, by developing murine CRC model, we found the primary tumor size was almost abolished and the survival rate was greatly improved by chemotherapy and CA3 combined treatment compared with negative control or chemotherapy treated alone. Collectively, our findings demonstrated that LASP1 could induce CRC tumor cells proliferation and migration through activating hippo signaling pathway component YAP1 and further enhancing Nanog expression.

Tumor supernatant derived from hepatocellular carcinoma cells treated with vincristine sulfate have therapeutic activity

Vincristine sulfate (VCR), a commonly used chemotherapeutic agent, kills cancer cells as well as the normal cells for its cytotoxicity. But it is still unclear whether it can exert therapeutic effect on untreated cancer cells by changing the supernatant of cancer cells. Here, we explored the subsequent cascade effects of the supernatant of cancer cells that were transiently treated with VCR on untreated tumor cells and its responsible mechanisms. VCR and three different hepatocellular carcinoma (HCC) cell lines were used for an experiment. The experiment was conducted in vitro to eliminate the body's internal factors and the effects of the immune system. The results suggested that drug-free tumor supernatant (TSN) could promote the differentiation, repress the transcription of liver cancer stem cell's markers and the proliferation in SMMC-7721, Bel-7402 and Huh7 cells. Furthermore, we found that the TSN could abolish YAP1 transcriptional activity to inhibit the proliferation and increase the transcriptional activity of HNF4α to promote the differentiation in SMMC-7721 and Bel-7402 cells. In conclusion, the TSN could inhibit the proliferation and induce differentiation in different HCC cells.

Therapeutic Targeting of Signaling Pathways Related to Cancer Stemness

The theory of cancer stem cells (CSCs) proposes that the different cells within a tumor, as well as metastasis deriving from it, are originated from a single subpopulation of cells with self-renewal and differentiation capacities. These cancer stem cells are supposed to be critical for tumor expansion and metastasis, tumor relapse and resistance to conventional therapies, such as chemo- and radiotherapy. The acquisition of these abilities has been attributed to the activation of alternative pathways, for instance, WNT, NOTCH, SHH, PI3K, Hippo, or NF-κB pathways, that regulate detoxification mechanisms; increase the metabolic rate; induce resistance to apoptotic, autophagic, and senescence pathways; promote the overexpression of drug transporter proteins; and activate specific stem cell transcription factors. The elimination of CSCs is an important goal in cancer therapeutic approaches because it could decrease relapses and metastatic dissemination, which are main causes of mortality in oncology patients. In this work, we discuss the role of these signaling pathways in CSCs along with their therapeutic potential.

Single-Cell Transcriptome Profiling of the Kidney Glomerulus Identifies Key Cell Types and Reactions to Injury

BACKGROUND

The glomerulus is a specialized capillary bed that is involved in urine production and BP control. Glomerular injury is a major cause of CKD, which is epidemic and without therapeutic options. Single-cell transcriptomics has radically improved our ability to characterize complex organs, such as the kidney. Cells of the glomerulus, however, have been largely underrepresented in previous single-cell kidney studies due to their paucity and intractability.

METHODS

Single-cell RNA sequencing comprehensively characterized the types of cells in the glomerulus from healthy mice and from four different disease models (nephrotoxic serum nephritis, diabetes, doxorubicin toxicity, and CD2AP deficiency).

RESULTS

All cell types in the glomerulus were identified using unsupervised clustering analysis. Novel marker genes and gene signatures of mesangial cells, vascular smooth muscle cells of the afferent and efferent arterioles, parietal epithelial cells, and three types of endothelial cells were identified. Analysis of the disease models revealed cell type-specific and injury type-specific responses in the glomerulus, including acute activation of the Hippo pathway in podocytes after nephrotoxic immune injury. Conditional deletion of YAP or TAZ resulted in more severe and prolonged proteinuria in response to injury, as well as worse glomerulosclerosis.

CONCLUSIONS

Generation of comprehensive high-resolution, single-cell transcriptomic profiles of the glomerulus from healthy and injured mice provides resources to identify novel disease-related genes and pathways.

Keratin 14-dependent disulfides regulate epidermal homeostasis and barrier function via 14-3-3σ and YAP1

The intermediate filament protein keratin 14 (K14) provides vital structural support in basal keratinocytes of epidermis. Recent studies evidenced a role for K14-dependent disulfide bonding in the organization and dynamics of keratin IFs in skin keratinocytes. Here we report that knock-in mice harboring a cysteine-to-alanine substitution at Krt14's codon 373 (C373A) exhibit alterations in disulfide-bonded K14 species and a barrier defect secondary to enhanced proliferation, faster transit time and altered differentiation in epidermis. A proteomics screen identified 14-3-3 as K14 interacting proteins. Follow-up studies showed that YAP1, a transcriptional effector of Hippo signaling regulated by 14-3-3sigma in skin keratinocytes, shows aberrant subcellular partitioning and function in differentiating Krt14 C373A keratinocytes. Residue C373 in K14, which is conserved in a subset of keratins, is revealed as a novel regulator of keratin organization and YAP function in early differentiating keratinocytes, with an impact on cell mechanics, homeostasis and barrier function in epidermis.

TEAD2 as a novel prognostic factor for hepatocellular carcinoma

TEA Domain Transcription Factors (TEADs) are important in development and serve essential roles in tumorigenesis; however, the role of TEAD2 expression in hepatocellular carcinoma (HCC) has not been widely examined. The present study was conducted to investigate the expression status of TEAD2 in HCC and to evaluate whether the expression of TEAD2 is associated with the prognosis of patients with HCC. mRNA expression data was retrieved for Hippo pathway genes of 50 normal control and 377 HCC samples from The Cancer Genome Atlas data portal. Gene set enrichment, GeneNeighbors, ClassNeighbors and survival analyses were then performed based on the gene expression levels. The mRNA expression of TEAD2 and VGLL4 was significantly higher in HCC compared with the normal control samples, and the mRNA expression of TEAD2 was higher in advanced stages than in early stages. Specifically, survival analysis revealed that higher mRNA expression of TEAD2 was significantly associated with a less favorable overall survival rate (P=0.0067) and there was a trend towards significance between higher mRNA expression of VGLL4 and poor overall survival rate (P=0.051). According to the gene set enrichment analysis, patients with higher mRNA expression of TEAD2 and VGLL4 had strongly enhanced epithelial-mesenchymal transition and angiogenesis, which are associated with tumor progression. In conclusion, increased mRNA expression of TEAD2 is associated with a poor prognosis in patients with HCC. TEAD2 may serve as a prognostic factor for HCC and a novel therapeutic target.

MMP24 as a Target of YAP is a Potential Prognostic Factor in Cancer Patients

The extracellular matrix (ECM) surrounding cancer cells becomes stiffer during tumor progression, which influences cancer cell behaviors such as invasion and proliferation through modulation of gene expression as well as remodeling of the actin cytoskeleton. In this study, we show that MMP24 encoding matrix metalloproteinase (MMP)-24 is a novel target gene of Yes-associated protein (YAP), a transcription coactivator known as a mechanotransducer. We first examined the effect of substrate stiffness on MMP24 expression in MCF-7 human breast cancer cells and showed that the expression of MMP24 was significantly higher in cells grown on stiff substrates than that on soft substrates. The MMP24 expression was significantly reduced by knockdown of YAP. In contrast, the expression of constitutively active YAP increased MMP24 promoter activity. In addition, binding of YAP to the MMP24 promoter was confirmed by the chromatin immunoprecipitation (ChIP) assay. These results show that ECM stiffening promotes YAP activation, thereby inducing MMP24 expression. Based on the Human Protein Atlas database, breast cancer patients with lower MMP24 expression exhibit the worse survival rates overall. Thus, MMP24 may negatively regulate the aggressiveness of cancer cells under the stiff ECM environment during tumor progression.

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.

The Hippo Tumor Suppressor Pathway (YAP/TAZ/TEAD/MST/LATS) and EGFR-RAS-RAF-MEK in cancer metastasis

Hippo Tumor Suppressor Pathway is the main pathway for cell growth that regulates tissue enlargement and organ size by limiting cell growth. This pathway is activated in response to cell cycle arrest signals (cell polarity, transduction, and DNA damage) and limited by growth factors or mitogens associated with EGF and LPA. The major pathway consists of the central kinase of Ste20 MAPK (Saccharomyces cerevisiae), Hpo (Drosophila melanogaster) or MST kinases (mammalian) that activates the mammalian AGC kinase dmWts or LATS effector (MST and LATS). YAP in the nucleus work as a cofactor for a wide range of transcription factors involved in proliferation (TEA domain family, TEAD1-4), stem cells (Oct4 mononuclear factor and SMAD-related TGFβ effector), differentiation (RUNX1), and Cell cycle/apoptosis control (p53, p63, and p73 family members). This is due to the diverse roles of YAP and may limit tumor progression and establishment. TEAD also coordinates various signal transduction pathways such as Hippo, WNT, TGFβ and EGFR, and effects on lack of regulation of TEAD cancerous genes, such as KRAS, BRAF, LKB1, NF2 and MYC, which play essential roles in tumor progression, metastasis, cancer metabolism, immunity, and drug resistance. However, RAS signaling is a pivotal factor in the inactivation of Hippo, which controls EGFR-RAS-RAF-MEK-ERK-mediated interaction of Hippo signaling. Thus, the loss of the Hippo pathway may have significant consequences on the targets of RAS-RAF mutations in cancer.

A novel strategy to block mitotic progression for targeted therapy

BACKGROUND

Blockade of mitotic progression is an ideal approach to induce mitotic catastrophe that suppresses cancer cell expansion. Cdc20 is a critical mitotic factor governing anaphase initiation and the exit from mitosis through recruiting substrates to APC/C for degradation. Results from recent TCGA (The Cancer Genome Atlas) and pathological studies have demonstrated a pivotal oncogenic role for Cdc20-APC/C in tumor progression as well as drug resistance. Thus, deprivation of the mitotic role for Cdc20-APC/C by either inhibition of Cdc20-APC/C activity or elimination of Cdc20 protein via induced protein degradation emerges as an effective therapeutic strategy to control cancer.

METHODS

We designed a proteolysis targeting chimera, called CP5V, which comprises a Cdc20 ligand and VHL binding moiety bridged by a PEG5 linker that induces Cdc20 degradation. We characterized the effect of CP5V in destroying Cdc20, arresting mitosis, and inhibiting tumor progression by measuring protein degradation, 3D structure dynamics, cell cycle control, tumor cell killing and tumor inhibition using human breast cancer xenograft mouse model.

FINDINGS

Results from our study demonstrate that CP5V can specifically degrade Cdc20 by linking Cdc20 to the VHL/VBC complex for ubiquitination followed by proteasomal degradation. Induced degradation of Cdc20 by CP5V leads to significant inhibition of breast cancer cell proliferation and resensitization of Taxol-resistant cell lines. Results based on a human breast cancer xenograft mouse model show a significant role for CP5V in suppressing breast tumor progression.

INTERPRETATION

CP5V-mediated degradation of Cdc20 could be an effective therapeutic strategy for anti-mitotic therapy.

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.

miR-22 Regulates Invasion, Gene Expression and Predicts Overall Survival in Patients with Clear Cell Renal Cell Carcinoma

Background:

Clear cell renal cell carcinoma (ccRCC) is molecularly diverse and distinct molecular subtypes show different clinical outcomes. MicroRNAs (miRNAs) are essential components of gene regulatory networks and play a crucial role in progression of many cancer types including ccRCC.

Objective:

Identify prognostic miRNAs and determine the role of miR-22 in ccRCC.

Methods:

Hierarchical clustering was done in R using gene expression profiles of over 450 ccRCC cases in The Cancer Genome Atlas (TCGA). Kaplan-Meier analysis was performed to identify prognostic miRNAs in the TCGA dataset. RNA-Seq was performed to identify miR-22 target genes in primary ccRCC cells and Matrigel invasion assay was performed to assess the effects of miR-22 overexpression on cell invasion.

Results:

Hierarchical clustering analysis using 2,621 prognostic genes previously identified by our group demonstrated that ccRCC patients with longer overall survival expressed lower levels of genes promoting proliferation or immune responses, while better maintaining gene expression associated with cortical differentiation and cell adhesion. Targets of 26 miRNAs were significantly enriched in the 2,621 prognostic genes and these miRNAs were prognostic by themselves. MiR-22 was associated with poor overall survival in the TCGA dataset. Overexpression of miR-22 promoted invasion of primary ccRCC cells in vitro and modulated transcriptional programs implicated in cancer progression including DNA repair, cell proliferation and invasion.

Conclusions:

Our results suggest that ccRCCs with differential clinical outcomes have distinct transcriptomes for which miRNAs could serve as master regulators. MiR-22, as a master regulator, promotes ccRCC progression at least in part by enhancing cell invasion.

Helicobacter pylori-induced YAP1 nuclear translocation promotes gastric carcinogenesis by enhancing IL-1β expression

Gastric cancer (GC) is one of the most common and malignant pathologies, and a significant portion of GC incidences develops from Helicobacter pylori (Hp)-induced chronic gastritis. Although the exact mechanisms of GC are complex and poorly understood, gastric carcinogenesis is a good model to investigate how inflammation and infection collaboratively promote tumorigenesis. Yes-associated protein 1 (YAP1) is the key effector of the Hippo pathway, which is silenced in most human cancers. Herein, we verified the tumor-promoting effect of YAP1 in vitro, in vivo, and in human specimens. We revealed that YAP1 displays nuclear translocation and works with TEAD to activate transcription of the crucial inflammatory cytokine IL-1β in gastric cells infected with Hp. As IL-1ß accounts for inflammation-associated tumorigenesis, this process can lead to gastric carcinogenesis. Thus, in addition to activating proliferation genes, YAP1 also plays a major role in inflammation amplification by activating inflammatory cytokine genes. Excitingly, our research demonstrates that transfection of mutant plasmid YAP-5SA/S94A or addition of the drug verteporfin, both of which are thought to disrupt the YAP1-TEAD interaction, can arrest the carcinogenesis process. These findings can provide new approaches to GC treatment.

Regulation of TEAD Transcription Factors in Cancer Biology

Transcriptional enhanced associate domain (TEAD) transcription factors play important roles during development, cell proliferation, regeneration, and tissue homeostasis. TEAD integrates with and coordinates various signal transduction pathways including Hippo, Wnt, transforming growth factor beta (TGFβ), and epidermal growth factor receptor (EGFR) pathways. TEAD deregulation affects well-established cancer genes such as KRAS, BRAF, LKB1, NF2, and MYC, and its transcriptional output plays an important role in tumor progression, metastasis, cancer metabolism, immunity, and drug resistance. To date, TEADs have been recognized to be key transcription factors of the Hippo pathway. Therefore, most studies are focused on the Hippo kinases and YAP/TAZ, whereas the Hippo-dependent and Hippo-independent regulators and regulations governing TEAD only emerged recently. Deregulation of the TEAD transcriptional output plays important roles in tumor progression and serves as a prognostic biomarker due to high correlation with clinicopathological parameters in human malignancies. In addition, discovering the molecular mechanisms of TEAD, such as post-translational modifications and nucleocytoplasmic shuttling, represents an important means of modulating TEAD transcriptional activity. Collectively, this review highlights the role of TEAD in multistep-tumorigenesis by interacting with upstream oncogenic signaling pathways and controlling downstream target genes, which provides unprecedented insight and rationale into developing TEAD-targeted anticancer therapeutics.

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.

Antiproliferative and Antimigratory Effects of a Novel YAP-TEAD Interaction Inhibitor Identified Using in Silico Molecular Docking

The Hippo pathway is an important regulator of cell growth, proliferation, and migration. TEAD transcription factors, which lie at the core of the Hippo pathway, are essential for regulation of organ growth and wound repair. Dysregulation of TEAD and its regulatory cofactor Yes-associated protein (YAP) have been implicated in numerous human cancers and hyperproliferative pathological processes. Hence, the YAP–TEAD complex is a promising therapeutic target. Here, we use in silico molecular docking using Bristol University Docking Engine to screen a library of more than 8 million druglike molecules for novel disrupters of the YAP–TEAD interaction. We report the identification of a novel compound (CPD3.1) with the ability to disrupt YAP–TEAD protein–protein interaction and inhibit TEAD activity, cell proliferation, and cell migration. The YAP–TEAD complex is a viable drug target, and CPD3.1 is a lead compound for the development of more potent TEAD inhibitors for treating cancer and other hyperproliferative pathologies.

Quantitative Real-Time PCR to Measure YAP/TAZ Activity in Human Cells

Transcription coactivators Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ, also known as WWTR1) are homologs of the Drosophila Yorkie (Yki) protein and are major downstream effectors of the evolutionarily conserved Hippo pathway. YAP/TAZ play critical roles in regulation of cell proliferation, apoptosis, and stemness, thus mediate functions of the Hippo pathway in organ size control and tumorigenesis. The Hippo pathway inhibits YAP/TAZ through phosphorylation, which leads to YAP/TAZ cytoplasmic retention and degradation. Dephosphorylated and nuclear-localized YAP/TAZ bind to transcription factors, especially the TEAD family proteins, thus transactivate the expression of specific genes. Therefore, measuring the expression level of YAP/TAZ target genes is a critical approach to assess Hippo pathway activity. Through gene expression profiling in different tissues and cells using techniques such as microarray and RNA-seq, many target genes of YAP/TAZ have been identified. Some of these genes were confirmed to be direct YAP/TAZ targets by chromatin immunoprecipitation (ChIP)-PCR or ChIP-seq. These works made it possible to quickly determine YAP/TAZ activity by measuring the mRNA levels of several YAP/TAZ target genes, such as CTGF, CYR61, and miR-130a by quantitative real-time PCR (qPCR). In this chapter, we demonstrate the use of qPCR to measure YAP/TAZ activity in MCF10A cells.

YAP/TAZ Signaling as a Molecular Link between Fibrosis and Cancer

Tissue fibrosis is a pathological condition that is associated with impaired epithelial repair and excessive deposition of extracellular matrix (ECM). Fibrotic lesions increase the risk of cancer in various tissues, but the mechanism linking fibrosis and cancer is unclear. Yes-associated protein (YAP) and the transcriptional coactivator with PDZ-binding motif (TAZ) are core components of the Hippo pathway, which have multiple biological functions in the development, homeostasis, and regeneration of tissues and organs. YAP/TAZ act as sensors of the structural and mechanical features of the cell microenvironment. Recent studies have shown aberrant YAP/TAZ activation in both fibrosis and cancer in animal models and human tissues. In fibroblasts, ECM stiffness mechanoactivates YAP/TAZ, which promote the production of profibrotic mediators and ECM proteins. This results in tissue stiffness, thus establishing a feed-forward loop of fibroblast activation and tissue fibrosis. In contrast, in epithelial cells, YAP/TAZ are activated by the disruption of cell polarity and increased ECM stiffness in fibrotic tissues, which promotes the proliferation and survival of epithelial cells. YAP/TAZ are also involved in the epithelial–mesenchymal transition (EMT), which contributes to tumor progression and cancer stemness. Importantly, the crosstalk with transforming growth factor (TGF)-β signaling and Wnt signaling is essential for the profibrotic and tumorigenic roles of YAP/TAZ. In this article, we review the latest advances in the pathobiological roles of YAP/TAZ signaling and their function as a molecular link between fibrosis and cancer.

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.

Yes-associated protein (YAP) in pancreatic cancer: at the epicenter of a targetable signaling network associated with patient survival

Pancreatic ductal adenocarcinoma (PDAC) is generally a fatal disease with no efficacious treatment modalities. Elucidation of signaling mechanisms that will lead to the identification of novel targets for therapy and chemoprevention is urgently needed. Here, we review the role of Yes-associated protein (YAP) and WW-domain-containing Transcriptional co-Activator with a PDZ-binding motif (TAZ) in the development of PDAC. These oncogenic proteins are at the center of a signaling network that involves multiple upstream signals and downstream YAP-regulated genes. We also discuss the clinical significance of the YAP signaling network in PDAC using a recently published interactive open-access database (www.proteinatlas.org/pathology) that allows genome-wide exploration of the impact of individual proteins on survival outcomes. Multiple YAP/TEAD-regulated genes, including AJUBA, ANLN, AREG, ARHGAP29, AURKA, BUB1, CCND1, CDK6, CXCL5, EDN2, DKK1, FOSL1,FOXM1, HBEGF, IGFBP2, JAG1, NOTCH2, RHAMM, RRM2, SERP1, and ZWILCH, are associated with unfavorable survival of PDAC patients. Similarly, components of AP-1 that synergize with YAP (FOSL1), growth factors (TGFα, EPEG, and HBEGF), a specific integrin (ITGA2), heptahelical receptors (P2Y₂R, GPR87) and an inhibitor of the Hippo pathway (MUC1), all of which stimulate YAP activity, are associated with unfavorable survival of PDAC patients. By contrast, YAP inhibitory pathways (STRAD/LKB-1/AMPK, PKA/LATS, and TSC/mTORC1) indicate a favorable prognosis. These associations emphasize that the YAP signaling network correlates with poor survival of pancreatic cancer patients. We conclude that the YAP pathway is a major determinant of clinical aggressiveness in PDAC patients and a target for therapeutic and preventive strategies in this disease.

Yes-associated protein (YAP) signaling contributes to pancreatic cancer progression and is associated with poor patient survival. Previous studies have shown that YAP activates genes involved in cell proliferation to incite tumor growth and metastasis. Enrique Rozengurt and colleagues at University of California Los Angeles review the latest knowledge on YAP signaling and used the open access database The Human Protein Atlas to analyze the gene expression profile and prognosis of 176 patients with pancreatic ductal adenocarcinoma. Activation of upstream or downstream elements of the YAP signaling pathway correlated with shorter survival in patients. Conversely, the activation of signaling pathways that oppose YAP signaling were associated with a more favorable prognosis. These findings highlight YAP signaling pathway components as both prognostic markers and potential targets for developing much needed therapeutic and preventative strategies.

p53 shades of Hippo

The three p53 family members, p53, p63 and p73, are structurally similar and share many biochemical activities. Yet, along with their common fundamental role in protecting genomic fidelity, each has acquired distinct functions related to diverse cell autonomous and non-autonomous processes. Similar to the p53 family, the Hippo signaling pathway impacts a multitude of cellular processes, spanning from cell cycle and metabolism to development and tumor suppression. The core Hippo module consists of the tumor-suppressive MST-LATS kinases and oncogenic transcriptional co-effectors YAP and TAZ. A wealth of accumulated data suggests a complex and delicate regulatory network connecting the p53 and Hippo pathways, in a highly context-specific manner. This generates multiple layers of interaction, ranging from interdependent and collaborative signaling to apparent antagonistic activity. Furthermore, genetic and epigenetic alterations can disrupt this homeostatic network, paving the way to genomic instability and cancer. This strengthens the need to better understand the nuances that control the molecular function of each component and the cross-talk between the different components. Here, we review interactions between the p53 and Hippo pathways within a subset of physiological contexts, focusing on normal stem cells and development, as well as regulation of apoptosis, senescence and metabolism in transformed cells.

ARRDC1 and ARRDC3 act as tumor suppressors in renal cell carcinoma by facilitating YAP1 degradation

The α-arrestins domain-containing 1 and 3 (ARRDC1 and ARRDC3) are two members of the α-arrestins family. Yes-associated protein 1 (YAP1) is a key downstream transcription co-activator of the Hippo pathway essential for cancer initiation, progression, or metastasis in clear cell renal cell carcinoma (ccRCC). The aim of this work was to elucidate the role of the α-arrestins in ccRCC tumorigenesis by identifying molecular interacting factors and exploring potential mechanisms. In this study, we identified YAP1 as a novel ARRDC3 interacting protein in RCC cells through tandem affinity purification and mass spectrometry. We confirmed that ARRDC1 and ARRDC3, but not other α-arrestin family proteins, interact with YAP1. Binding of ARRDC1/3 to YAP1 is mediated through the WW domains of YAP1 and the PPXY motifs of ARRDC1/3. Functional analysis of ARRDC1/3 by lentiviral shRNA revealed a role for ARRDC1/3 in suppression of cell growth, migration, invasion and epithelial-mesenchymal transition in ccRCC cells, and these effects were mediated, at least in part, through YAP1. Mechanically, ARRDC1/3 negatively regulates YAP1 protein stability by facilitating E3 ubiquitin ligase Itch-mediated ubiquitination and degradation of YAP1. Moreover, ARRDC1/3 mRNA levels were significantly downregulated in ccRCC specimens. A negative correlation was identified between ARRDC3 and YAP1 expression in ccRCC specimens by immunohistochemistry. This study revealed a novel mechanism for ARRDC1/3 in the regulation of YAP1 stability and provided insight in understanding the relationship between ARRDC1/3 downregulation and aberrant Hippo-YAP1 pathway activation in ccRCC.

The Role of Compounds Derived from Natural Supplement as Anticancer Agents in Renal Cell Carcinoma: A Review

Renal Cell Carcinoma (RCC) is the most prominent kidney cancer derived from renal tubules and accounts for roughly 85% of all malignant kidney cancer. Every year, over 60,000 new cases are registered, and about 14,000 people die from RCC. The incidence of this has been increasing significantly in the U.S. and other countries. An increased understanding of molecular biology and the genomics of RCC has uncovered several signaling pathways involved in the progression of this cancer. Significant advances in the treatment of RCC have been reported from agents approved by the Food and Drug Administration (FDA) that target these pathways. These agents have become drugs of choice because they demonstrate clinical benefit and increased survival in patients with metastatic disease. However, the patients eventually relapse and develop resistance to these drugs. To improve outcomes and seek approaches for producing long-term durable remission, the search for more effective therapies and preventative strategies are warranted. Treatment of RCC using natural products is one of these strategies to reduce the incidence. However, recent studies have focused on these chemoprevention agents as anti-cancer therapies given they can inhibit tumor cell grow and lack the severe side effects common to synthetic compounds. This review elaborates on the current understanding of natural products and their mechanisms of action as anti-cancer agents. The present review will provide information for possible use of these products alone or in combination with chemotherapy for the prevention and treatment of RCC.