TEAD4 overexpression promotes epithelial-mesenchymal transition and associates with aggressiveness and adverse prognosis in head neck squamous cell carcinoma

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

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

Transcription Factors and Markers Related to Epithelial-Mesenchymal Transition and Their Role in Resistance to Therapies in Head and Neck Cancers

Head and neck cancers (HNCs) are heterogeneous and aggressive tumors of the upper aerodigestive tract. Although various histological types exist, the most common is squamous cell carcinoma (HNSCC). The incidence of HNSCC is increasing, making it an important public health concern. Tumor resistance to contemporary treatments, namely, chemo- and radiotherapy, and the recurrence of the primary tumor after its surgical removal cause huge problems for patients. Despite recent improvements in these treatments, the 5-year survival rate is still relatively low. HNSCCs may develop local lymph node metastases and, in the most advanced cases, also distant metastases. A key process associated with tumor progression and metastasis is epithelial-mesenchymal transition (EMT), when poorly motile epithelial tumor cells acquire motile mesenchymal characteristics. These transition cells can invade different adjacent tissues and finally form metastases. EMT is governed by various transcription factors, including the best-characterized TWIST1 and TWIST2, SNAIL, SLUG, ZEB1, and ZEB2. Here, we highlight the current knowledge of the process of EMT in HNSCC and present the main protein markers associated with it. This review focuses on the transcription factors related to EMT and emphasizes their role in the resistance of HNSCC to current chemo- and radiotherapies. Understanding the role of EMT and the precise molecular mechanisms involved in this process may help with the development of novel anti-cancer therapies for this type of tumor.

TEAD4: A key regulator of tumor metastasis and chemoresistance - Mechanisms and therapeutic implications

Cancer metastasis is a complex process influenced by various factors, including epithelial-mesenchymal transition (EMT), tumor cell proliferation, tumor microenvironment, and cellular metabolic status, which remains a significant challenge in clinical oncology, accounting for a majority of cancer-related deaths. TEAD4, a key mediator of the Hippo signaling pathway, has been implicated in regulating these factors that are all critical in the metastatic cascade. TEAD4 drives tumor metastasis and chemoresistance, and its upregulation is associated with poor prognosis in many types of cancers, making it an attractive target for therapeutic intervention. TEAD4 promotes EMT by interacting with coactivators and activating the transcription of genes involved in mesenchymal cell characteristics and extracellular matrix remodeling. Additionally, TEAD4 enhances the stemness of cancer stem cells (CSCs) by regulating the expression of genes associated with CSC maintenance. TEAD4 contributes to metastasis by modulating the secretion of paracrine factors and promoting heterotypic cellular communication. In this paper, we highlight the central role of TEAD4 in cancer metastasis and chemoresistance and its impact on various aspects of tumor biology. Understanding the mechanistic basis of TEAD4-mediated processes can facilitate the development of targeted therapies and combination approaches to combat cancer metastasis and improve treatment outcomes.

Transcription factor TEAD4 facilitates glycolysis and proliferation of gastric cancer cells by activating PKMYT1

BACKGROUND

Gastric cancer (GC) ranks third for cancer deaths worldwide, and glycolysis is a hallmark of several cancers, including GC. TEAD4 plays a role in establishing an oncogenic cascade in cancers, including GC. Whether TEAD4 can influence the glycolysis of GC cells remains uncovered. Hence, this study attempted to investigate the impact on glycolysis of GC cells by TEAD4.

METHODS

By using bioinformatics analysis, differentially expressed mRNAs were screened, and downstream regulatory genes were predicted. Expression levels of TEAD4 and PKMYT1 were assessed by qRT-PCR. The binding sites between TEAD4 and PKMYT1 were predicted by the JASPAR database, meanwhile their modulatory relationship was confirmed through dual-luciferase assay and chromatin Immunoprecipitation (ChIP). Cell viability and proliferation were assayed via CCK-8 and colony formation assays. Glycolysis was measured by assaying extracellular acidification rate, oxygen consumption rate, and production of pyruvic acid, lactate, citrate, and malate. Expression levels of proteins (HK-2 and PKM2) related to glycolysis were assessed by Western blot.

RESULTS

TEAD4 was upregulated in GC tissues and cells. TEAD4 knockdown substantially repressed glycolysis and proliferation of GC cells. PKMYT1, the target gene downstream of TEAD4, was identified via bioinformatics prediction, and its expression was elevated in GC. Dual-luciferase and ChIP assay validated the targeted relationship between the promoter region of PKMYT1 and TEAD4. As revealed by rescue experiments, the knockdown of TEAD4 reversed the stimulative effect on GC cell glycolysis and proliferation by forced expression of PKMYT1.

CONCLUSION

TEAD4 activated PKMYT1 to facilitate the proliferation and glycolysis of GC cells. TEAD4 and PKMYT1 may be possible therapeutic targets for GC.

A sialyltransferases-related gene signature serves as a potential predictor of prognosis and therapeutic response for bladder cancer

BACKGROUND

Aberrant glycosylation, catalyzed by the specific glycosyltransferase, is one of the dominant features of cancers. Among the glycosyltransferase subfamilies, sialyltransferases (SiaTs) are an essential part which has close linkages with tumor-associated events, such as tumor growth, metastasis and angiogenesis. Considering the relationship between SiaTs and cancer, the current study attempted to establish an effective prognostic model with SiaTs-related genes (SRGs) to predict patients' outcome and therapeutic responsiveness of bladder cancer.

METHODS

RNA-seq data, clinical information and genomic mutation data were downloaded (TCGA-BLCA and GSE13507 datasets). The comprehensive landscape of the 20 SiaTs was analyzed, and the differentially expressed SiaTs-related genes were screened with "DESeq2" R package. ConsensusClusterPlus was applied for clustering, following with survival analysis with Kaplan-Meier curve. The overall survival related SRGs were determined with univariate Cox proportional hazards regression analysis, and the least absolute shrinkage and selection operator (LASSO) regression analysis was performed to generate a SRGs-related prognostic model. The predictive value was estimated with Kaplan-Meier plot and the receiver operating characteristic (ROC) curve, which was further validated with the constructed nomogram and decision curve.

RESULTS

In bladder cancer tissues, 17 out of the 20 SiaTs were differentially expressed with CNV changes and somatic mutations. Two SiaTs_Clusters were determined based on the expression of the 20 SiaTs, and two gene_Clusters were identified based on the expression of differentially expressed genes between SiaTs_Clusters. The SRGs-related prognostic model was generated with 7 key genes (CD109, TEAD4, FN1, TM4SF1, CDCA7L, ATOH8 and GZMA), and the accuracy for outcome prediction was validated with ROC curve and a constructed nomogram. The SRGs-related prognostic signature could separate patients into high- and low-risk group, where the high-risk group showed poorer outcome, more abundant immune infiltration, and higher expression of immune checkpoint genes. In addition, the risk score derived from the SRGs-related prognostic model could be utilized as a predictor to evaluate the responsiveness of patients to the medical therapies.

CONCLUSIONS

The SRGs-related prognostic signature could potentially aid in the prediction of the survival outcome and therapy response for patients with bladder cancer, contributing to the development of personalized treatment and appropriate medical decisions.

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.

Searching for Novel Biomarkers in Thymic Epithelial Tumors: Immunohistochemical Evaluation of Hippo Pathway Components in a Cohort of Thymic Epithelial Tumors

Given the pivotal role of the Hippo pathway in different facets of tumorigenesis, which has been vigorously established in multiple heterogenous malignancies, we attempted to evaluate its potential utility as a prognostic-predictive biomarker in thymic epithelial tumors (TETs). For this purpose, we performed a comprehensive immunohistochemical analysis of four Hippo cascade components (YAP, TAZ, TEAD4 and LATS1) in a sizeable cohort of TETs and attempted to identify possible correlations of their H-score with various clinicopathological parameters. TAZ and TEAD4 displayed both cytoplasmic and nuclear immunoreactivity in almost equal frequency, with their cytoplasmic H-score being strongly associated with more aggressive high-grade tumors (type B3, thymic carcinoma) and more advanced pathological stages. On the other hand, a primarily nuclear staining pattern was encountered in both YAP and LATS1, with the YAP nuclear H-score being higher in more indolent (type A) and earlier stage tumors. Interestingly, none of the four examined factors displayed any statistically significant correlation with patient overall (OS) or disease-free survival (DFS). In summary, our results provide some initial insight into the expression profile of these core Hippo pathway components in thymic neoplasms and point towards some clear associations with tumor characteristics, which are of paramount translational-clinical research with profound implications in therapeutic targeting of this pathway in the context of precision medicine.

BORIS/CTCFL-mediated chromatin accessibility alterations promote a pro-invasive transcriptional signature in melanoma cells

Melanoma is the deadliest form of skin cancer, due to its tendency to metastasize early. Brother of regulator of imprinted sites (BORIS), also known as CCCTC binding factor-like (CTCFL), is a transcription regulator that becomes ectopically expressed in melanoma. We recently showed that BORIS contributes to melanoma phenotype switching by altering the gene expression program of melanoma cells from an intermediate melanocytic state toward a more mesenchymal-like state. However, the mechanism underlying this transcriptional switch remains unclear. Here, ATAC-seq was used to study BORIS-mediated chromatin accessibility alterations in melanoma cells harboring an intermediate melanocytic state. The gene set that gained promoter accessibility, following ectopic BORIS expression, showed enrichment for biological processes associated with melanoma invasion, while promoters of genes associated with proliferation showed reduced accessibility. Integration of ATAC-seq and RNA-seq data demonstrated that increased chromatin accessibility was associated with transcriptional upregulation of genes involved in tumor progression processes, and the aberrant activation of oncogenic transcription factors, while reduced chromatin accessibility and downregulated genes were associated with repressed activity of tumor suppressors and proliferation factors. Together, these findings indicate that BORIS mediates transcriptional reprogramming in melanoma cells by altering chromatin accessibility and gene expression, shifting the cellular transcription landscape of melanoma cells toward a mesenchymal-like genetic signature.

Therapeutic targeting of TEAD transcription factors in cancer

The Hippo signaling pathway inhibits the activity of the oncogenic YAP (Yes-associated protein)/TAZ (transcriptional co-activator with PDZ-binding motif)-TEAD (TEA/ATTS domain) transcriptional complex. In cancers, inactivating mutations in upstream Hippo components and/or enhanced activity of YAP/TAZ and TEAD have been observed. The activity of this transcriptional complex can be effectively inhibited by targeting the TEAD family of transcription factors. The development of TEAD inhibitors has been driven by the discovery that TEAD has druggable hydrophobic pockets, and is currently at the clinical development stage. Three small molecule TEAD inhibitors are currently being tested in Phase I clinical trials. In this review, we highlight the role of TEADs in cancer, discuss various avenues through which TEAD activity can be inhibited, and outline the opportunities for the administration of TEAD inhibitors.

MAD2L1 is transcriptionally regulated by TEAD4 and promotes cell proliferation and migration in colorectal cancer

The molecular mechanism of network regulation in the occurrence and development of colorectal cancer (CRC) has been constantly improved. Here, we investigated the biological effects of TEAD4-MAD2L1 axis on proliferation and metastasis of human CRC cells. This study revealed that the expressions of MAD2L1 and TEAD4 in CRC tissues and CRC cell lines were significantly higher than those in adjacent epithelial tissues and normal intestinal epithelial cell line NCM460, and their expressions were significantly positively correlated; Moreover, inhibiting the expression of MAD2L1 or TEAD4 can inhibit the proliferation and migration of CRC cells and promote apoptosis. In addition, the promoter region of MAD2L1 gene has a TEAD4 binding site (motif sequence), and the transcription of MAD2L1 is positively regulated by TEAD4 protein; The inhibition of promotion/migration and promotion of apoptosis of CRC cells by silencing TEAD4 can be saved by the high expression of MAD2L1. In conclusion, our study suggests that the transcription and expression of MAD2L1 is regulated by TEAD4, which further promotes the proliferation and migration of CRC cells in vitro and in vivo, and inhibits apoptosis. MAD2L1 and TEAD4 are potential biomarkers for colorectal cancer.

miR-125b Promotes the Proliferation, Migration and Invasion of Oral Squamous Cell Carcinoma (OSCC)

miR-125b is involved in several tumors. However, miR-125b’s role in oral squamous cell carcinoma (OSCC) is unclear. Tumor tissues and oral normal mucosa tissues of OSCC patients were collected to measure miR-125b level. Oral cancer Tca8113 cells were separated into control group, miR-125b inhibitor group, and miR-125b mimics group, followed by measuring miR-125b level by real time PCR, cell survival, migration and invasion, PI3K/mTOR signaling protein level by Western blot. miR-125b was upregulated in OSCC tumor tissues and related to clinical/TNM stage, metastasis and overall survival (P < 0.05). miR-125b overexpression significantly promoted tumor cell behaviors and increased PI3K/mTOR phosphorylation (P < 0.05); while inhibiting miR-125b expression significantly inhibited tumor cell biological behaviors, and decreased PI3K/mTOR phosphorylation (P < 0.05). miR-125b level is increased in OSCC tumor tissues, which is related to clinicopathological characteristics. miR-125b overexpression promotes OSCC cell behaviors by regulating PI3K/mTOR signaling.

MMP1 Overexpression Promotes Cancer Progression and Associates with Poor Outcome in Head and Neck Carcinoma

Matrix metalloproteinase-1 (MMP1) has been reported to play key roles in a variety of cancers by degrading the extracellular matrix. However, its carcinogenic roles have not been shown yet in head and neck squamous cell carcinoma (HNSCC). This study aimed to elucidate its expression pattern and functional roles as well as clinical significance in HNSCC. The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and immunohistochemistry (IHC) were utilized to determine the MMP1 expression pattern and the associations between its expression and patients' outcome in HNSCC. Mice tongue squamous cell carcinoma model induced by 4-nitroquinoline 1-oxide (4NQO) and siRNA-mediated cellular assay in vitro were utilized to evaluate the oncogenic role of MMP1. The biological functions and cancer-related pathways involved in MMP1-related genes were found through bioinformatics analysis. Both mRNA and protein abundance of MMP1 were highly increased in HNSCC as compared to its non-tumor counterparts. MMP1 overexpression positively correlated with advanced tumor size, cervical node metastasis, and advanced pathological grade and lower patients' survival. In the 4NQO-induced animal model, MMP1 expression increased along with the progression of the disease. In HNSCC cells, siRNA-mediated knockdown of MMP1 significantly inhibited cell proliferation, migration, and invasion and activated apoptosis and epithelia-mesenchymal transition (EMT). GSEA, GO, and KEGG analyses showed that MMP1 expression was significantly related to cancer-related pathways and cancer-related functions. Together, our results demonstrated MMP1 serves as a novel prognostic biomarker and putative oncogene in HNSCC.

Knockdown of HSP110 attenuates hypoxia-induced pulmonary hypertension in mice through suppression of YAP/TAZ-TEAD4 pathway

Background

Pulmonary hypertension (PH) is a progressive and fatal cardiopulmonary disease characterized by pulmonary vascular remodeling and increased pulmonary vascular resistance and artery pressure. Vascular remodeling is associated with the excessive cell proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). In this paper, the effects of heat shock protein-110 (HSP110) on PH were investigated.

Methods

The C57BL/6 mice and human PASMCs (HPASMCs) were respectively exposed to hypoxia to establish and simulate PH model in vivo and cell experiment in vitro. To HSP110 knockdown, the hypoxia mice and HPASMCs were infected with adeno-associated virus or adenovirus carring the shRNAs (short hairpin RNAs) for HSP110 (shHSP110). For HSP110 and yes-associated protein (YAP) overexpression, HPASMCs were infected with adenovirus vector carring the cDNA of HSP110 or YAP. The effects of HSP110 on PH development in mice and cell proliferation, migration and autophagy of PASMCs under hypoxia were assessed. Moreover, the regulatory mechanisms among HSP110, YAP and TEA domain transcription factor 4 (TEAD4) were investigated.

Results

We demonstrated that expression of HSP110 was significantly increased in the pulmonary arteries of mice and HPASMCs under hypoxia. Moreover, knockdown of HSP110 alleviated hypoxia-induced right ventricle systolic pressure, vascular wall thickening, right ventricular hypertrophy, autophagy and proliferation of PASMCs in mice. In addition, knockdown of HSP110 inhibited the increases of proliferation, migration and autophagy of HPASMCs that induced by hypoxia in vitro. Mechanistically, HSP110 knockdown inhibited YAP and transcriptional co-activator with PDZ-binding motif (TAZ) activity and TEAD4 nuclear expression under hypoxia. However, overexpression of HSP110 exhibited the opposite results in HPASMCs. Additionally, overexpression of YAP partially restored the effects of shHSP110 on HPASMCs. The interaction of HSP110 and YAP was verified. Moreover, TEAD4 could promote the transcriptional activity of HSP110 by binding to the HSP110 promoter under hypoxia.

Conclusions

Our findings suggest that HSP110 might contribute to the development of PH by regulating the proliferation, migration and autophagy of PASMCs through YAP/TAZ-TEAD4 pathway, which may help to understand deeper the pathogenic mechanism in PH development.

TEAD4 functions as a prognostic biomarker and triggers EMT via PI3K/AKT pathway in bladder cancer

Background

The distant metastasis is the primary cause of cancer morbidity and mortality for bladder cancer (BLCA) paitents. All the recommended therapy for it largely depends on how far the cancer has invaded. It has been confirmed that epithelial to mesenchymal transition (EMT) is the leading reason for the BLCA metastasis which makes BLCA difficult to cure. The aim of the present study is to identify the BLCA-related genes that can be used as the new prognostic biomarker and treatment target, and to investigate the functional mechanisms of TEAD4 in EMT dysregulation.

Methods

The "limma" R package was used to identify the differentially expressed genes (DEGs) between the normal and the tumor samples from TCGA BLCA and GTEx databases. Kaplan–Meier and UniCox analysis were used to filter DEGs with prognostic value in BLCA. Step muti-Cox analysis was used to construct a prognostic risk score model based on clinical phenotype characters. Gene set enrichment analysis (GSEA) was performed to explore the possible molecular mechanisms affecting the prognosis in BLCA. Unsupervised hierarchical clustering analysis was performed to evaluate the effects of EMT process on the prognosis. Single-sample GSEA (ssGSEA) was used to calculate the correlation betweeen the expression of DEGs and EMT enrichment scores. TEAD4 expression and its association with pathological grading and survival were appraised in samples from TCGA dataset and BLCA tissue microarray. Colony formation assays and CCK8 assays were performed to study the changes in BLCA cell proliferation when the TEAD4 levels was down- or up-regulated in BLCA cells. Transwell and wound healing assays were utilized to analyze the impact of TEAD4 on the invasion and metastasis of the BLCA cells. Western Blot was carried out to detect the changes of EMT-related markers and the active molecules involved in PI3K/AKT signaling in BLCA cells. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was conducted on the genes related to TEAD4 expression. 740Y-P (activator of PI3K/AKT pathway) and LY294002 (inhibitor of PI3K/AKT pathway) were applied to evaluate the contribution of PI3K/AKT signaling pathway in the EMT of BLCA cells. To examine the in vivo effect of TEAD4 on tumor metastasis, we designed a metastatic nude-mouse model by tail vein injection of TEAD4-knockdown BLCA cells. And PET/CT imaging was used to assess the extent of lung metastases.

Results

A total of 1592 DEGs were recognized, among which 4 DEGs have been identified as independent prognostic factors for BLCA, such as FASN, IGFL2, PLOD1 and TEAD4. TCGA BLCA samples were divided into significantly different low- and high-risk groups according to the median risk score; GSEA analysis showed that HALLMARK EMT pathway was the top enriched gene signature when compared high-risk and low-risk groups, which was also verified by unsupervised cluster analysis. EMT signature-derived ssGSEA scores demonstrated that TEAD4 had the most positive correlation with EMT process. In addition, TEAD4 expression was upregulated in TCGA BLCA samples and correlated with pT stage, tumor stage and tumor grade. Functional studies showed that TEAD4 knockdown via lentiviral TEAD4 shRNA inhibited cell migration and invasion in vitro and in vivo, with the reduced expression of EMT related markers in BLCA cell lines; the migration and invasion of TEAD4 knockdown cells could be restored by ectopic expression of TEAD4. Meanwhile, KEGG enrichment analysis of genes related to TEAD4 expression showed that enrichment was significantly related to PI3K/AKT pathway. The pathway inhibitor LY294002 blocked the TEAD4-induced enhancement of migration and invasion as well as the expression EMT-related markers, whereas the agonist 740Y-P rescued the decreased migration, invasion and EMT induced by TEAD4 knockdown.

Conclusions

TEAD4 is closely correlated with poor prognosis in BLCA and mediates its metastasis through regulating EMT via PI3K/AKT pathway, proving that TEAD4 is not only an effective biomarker for predicting the prognosis but also a great potential target for treatment of metastatic BLCA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02377-3.

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.

Vestigial-like family member 3 stimulates cell motility by inducing high-mobility group AT-hook 2 expression in cancer cells

Vestigial‐like family member 3 (VGLL3) is a cofactor for TEA domain transcription factors (TEADs). Although VGLL3 is known to be highly expressed and stimulate cell proliferation in mesenchymal cancer cells, its involvement in mesenchymal phenotypes is largely unknown. In this study, we found that VGLL3 promotes epithelial‐to‐mesenchymal transition (EMT)‐like phenotypic changes. We found that A549 human lung cancer cells stably expressing VGLL3 exhibit spindle‐like morphological changes, reduction in the epithelial marker E‐cadherin and induction of the mesenchymal marker Snail. Notably, VGLL3‐expressing cells exhibited enhanced motility. The DNA‐binding protein high‐mobility group AT‐hook 2 (HMGA2) was found to be a target of the VGLL3‐TEAD4 complex, and HMGA2 knockdown repressed EMT‐like phenotypic changes in VGLL3‐expressing cells. VGLL3‐dependent phenotypic changes are involved in transforming growth factor‐β (TGF‐β)‐induced EMT progression. VGLL3 or HMGA2 knockdown repressed the motility of the mesenchymal breast cancer MDA‐MB‐231 cells. Importantly, high levels of VGLL3 expression were shown to have a positive correlation with poor prognosis in various human cancers, such as breast, colon, ovarian, head and neck, pancreatic, renal, gastric and cervical cancers. These results suggest that VGLL3 promotes EMT‐like cell motility by inducing HMGA2 expression and accelerates cancer progression.

The Hippo pathway in cancer: YAP/TAZ and TEAD as therapeutic targets in cancer

Tumorigenesis is a highly complex process, involving many interrelated and cross-acting signalling pathways. One such pathway that has garnered much attention in the field of cancer research over the last decade is the Hippo signalling pathway. Consisting of two antagonistic modules, the pathway plays an integral role in both tumour suppressive and oncogenic processes, generally via regulation of a diverse set of genes involved in a range of biological functions. This review discusses the history of the pathway within the context of cancer and explores some of the most recent discoveries as to how this critical transducer of cellular signalling can influence cancer progression. A special focus is on the various recent efforts to therapeutically target the key effectors of the pathway in both preclinical and clinical settings.

Epithelial-to-Mesenchymal Transition-Derived Heterogeneity in Head and Neck Squamous Cell Carcinomas

Simple Summary

Head and neck squamous cell carcinomas (HNSCC) are common malignancies with considerable morbidity and a high death toll worldwide. Resistance towards multi-modal therapy modalities composed of surgery, irradiation, chemo- and immunotherapy represents a major obstacle in the efficient treatment of HNSCC patients. Patients frequently show nodal metastases at the time of diagnosis and endure early relapses, oftentimes in the form of local recurrences. Differentiation programs such as the epithelial-to-mesenchymal transition (EMT) allow individual tumor cells to adopt cellular functions that are central to the development of metastases and treatment resistance. In the present review article, the molecular basis and regulation of EMT and its impact on the progression of HNSCC will be addressed.

Abstract

Head and neck squamous cell carcinomas (HNSCC) are common tumors with a poor overall prognosis. Poor survival is resulting from limited response to multi-modal therapy, high incidence of metastasis, and local recurrence. Treatment includes surgery, radio(chemo)therapy, and targeted therapy specific for EGFR and immune checkpoint inhibition. The understanding of the molecular basis for the poor outcome of HNSCC was improved using multi-OMICs approaches, which revealed a strong degree of inter- and intratumor heterogeneity (ITH) at the level of DNA mutations, transcriptome, and (phospho)proteome. Single-cell RNA-sequencing (scRNA-seq) identified RNA-expression signatures related to cell cycle, cell stress, hypoxia, epithelial differentiation, and a partial epithelial-to-mesenchymal transition (pEMT). The latter signature was correlated to nodal involvement and adverse clinical features. Mechanistically, shifts towards a mesenchymal phenotype equips tumor cells with migratory and invasive capacities and with an enhanced resistance to standard therapy. Hence, gradual variations of EMT as observed in HNSCC represent a potent driver of tumor progression that could open new paths to improve the stratification of patients and to innovate approaches to break therapy resistance. These aspects of molecular heterogeneity will be discussed in the present review.

Discovery of a subtype-selective, covalent inhibitor against palmitoylation pocket of TEAD3

The TEA domain (TEAD) family proteins (TEAD1‒4) are essential transcription factors that control cell differentiation and organ size in the Hippo pathway. Although the sequences and structures of TEAD family proteins are highly conserved, each TEAD isoform has unique physiological and pathological functions. Therefore, the development and discovery of subtype selective inhibitors for TEAD protein will provide important chemical probes for the TEAD-related function studies in development and diseases. Here, we identified a novel TEAD1/3 covalent inhibitor (DC-TEADin1072) with biochemical IC₅₀ values of 0.61 ± 0.02 and 0.58 ± 0.12 μmol/L against TEAD1 and TEAD3, respectively. Further chemical optimization based on DC-TEAD in 1072 yielded a selective TEAD3 inhibitor DC-TEAD3in03 with the IC₅₀ value of 0.16 ± 0.03 μmol/L, which shows 100-fold selectivity over other TEAD isoforms in activity-based protein profiling (ABPP) assays. In cells, DC-TEAD3in03 showed selective inhibitory effect on TEAD3 in GAL4-TEAD (1–4) reporter assays with the IC₅₀ value of 1.15 μmol/L. When administered to zebrafish juveniles, experiments showed that DC-TEAD3in03 reduced the growth rate of zebrafish caudal fins, indicating the importance of TEAD3 activity in controlling proportional growth of vertebrate appendages.

SNAI2 is induced by transforming growth factor-β1, but is not essential for epithelial-mesenchymal transition in human keratinocyte HaCaT cells

Epithelial-mesenchymal transition (EMT) is a cellular process in which epithelial cells lose their epithelial traits and shift to the mesenchymal phenotype, and is associated with various biological events, such as embryogenesis, wound healing and cancer progression. The transcriptional program that promotes phenotype switching is dynamically controlled by transcription factors during EMT, including Snail (SNAI1), twist family bHLH transcription factor (TWIST) and zinc finger E-box binding homeobox 1 (ZEB1). The present study aimed to investigate the molecular mechanisms underlying EMT in squamous epithelial cells. Western blot analysis and immunocytochemical staining identified Slug (SNAI2) as a transcription factor that is induced during transforming growth factor (TGF)-β1-mediated EMT in the human keratinocyte cell line HaCaT. The effect of SNAI2 overexpression and knockdown on the phenotypic characteristics of HaCaT cells was evaluated. Filamentous actin staining and western blot analysis revealed that the overexpression of SNAI2 did not induce the observed EMT-related phenotypic changes. In addition, SNAI2 knockdown demonstrated almost no impact on the EMT phenotypes induced by TGF-β1. Notably, DNA microarray analysis followed by comprehensive bioinformatics analysis revealed that the differentially expressed genes upregulated by TGF-β1 were significantly enriched in cell adhesion and extracellular matrix binding, whereas the genes downregulated in response to TGF-β1 were significantly enriched in the cell cycle. No enriched gene ontology term and biological pathways were identified in the differentially expressed gene sets of SNAI2-overexpressing cells. In addition, the candidates for master transcription factors regulating the TGF-β1-induced EMT were identified using transcription factor enrichment analysis. In conclusion, the results of study demonstrated that SNAI2 does not play an essential role in the EMT of HaCaT cells and identified candidate transcription factors that may be involved in EMT-related gene expression induced by TGF-β1. These findings may enhance the understanding of molecular events in EMT and contribute to the development of a novel therapeutic approach against EMT in cancers and wound healing.

Conservation of Epithelial-to-Mesenchymal Transition Process in Neural Crest Cells and Metastatic Cancer

Epithelial to mesenchymal transition (EMT) is a highly conserved cellular process in several species, from worms to humans. EMT plays a fundamental role in early embryogenesis, wound healing, and cancer metastasis. For neural crest cell (NCC) development, EMT typically results in forming a migratory and potent cell population that generates a wide variety of cell and tissue, including cartilage, bone, connective tissue, endocrine cells, neurons, and glia amongst many others. The degree of conservation between the signaling pathways that regulate EMT during development and metastatic cancer (MC) has not been fully established, despite ample studies. This systematic review and meta-analysis dissects the major signaling pathways involved in EMT of NCC development and MC to unravel the similarities and differences. While the FGF, TGFβ/BMP, SHH, and NOTCH pathways have been rigorously investigated in both systems, the EGF, IGF, HIPPO, Factor Receptor Superfamily, and their intracellular signaling cascades need to be the focus of future NCC studies. In general, meta-analyses of the associated signaling pathways show a significant number of overlapping genes (particularly ligands, transcription regulators, and targeted cadherins) involved in each signaling pathway of both systems without stratification by body segments and cancer type. Lack of stratification makes it difficult to meaningfully evaluate the intracellular downstream effectors of each signaling pathway. Finally, pediatric neuroblastoma and melanoma are NCC-derived malignancies, which emphasize the importance of uncovering the EMT events that convert NCC into treatment-resistant malignant cells.

Identification of a Novel Epithelial-Mesenchymal Transition Gene Signature Predicting Survival in Patients With HNSCC

Head and neck squamous cell cancer (HNSCC) is one of the most common types of cancer worldwide. There have been many reports suggesting that biomarkers explored via database mining plays a critical role in predicting HNSCC prognosis. However, a single biomarker for prognostic analysis is not adequate. Additionally, there is growing evidence indicating that gene signature could be a better choice for HNSCC prognosis. We performed a comprehensive analysis of mRNA expression profiles using clinical information of HNSCC patients from The Cancer Genome Atlas (TCGA). Gene Set Enrichment Analysis (GSEA) was performed, and we found that a set of genes involved in epithelial mesenchymal transition (EMT) contributed to HNSCC. Cox proportional regression model was used to identify a four-gene (WIPF1, PPIB, BASP1, PLOD2) signature that were significantly associated with overall survival (OS), and all the four genes were significantly upregulated in tumor tissues. We successfully classified the patients with HNSCC into high-risk and low-risk groups, where in high-risk indicated poorer patient prognosis, indicating that this gene signature might be a novel potential biomarker for the prognosis of HNSCC. The prognostic ability of the gene signature was further validated in an independent cohort from the Gene Expression Omnibus (GEO) database. In conclusion, we identified a four-EMT-based gene signature which provides the potentiality to serve as novel independent biomarkers for predicting survival in HNSCC patients, as well as a new possibility for individualized treatment of HNSCC.

TEAD4 as a Prognostic Marker Promotes Cell Migration and Invasion of Urinary Bladder Cancer via EMT

Purpose

As a member of TEA Domain Transcription Factors (TEADs), TEAD4 was found to be upregulated in urinary bladder cancer (UBC). This study focused on investigating the clinical value and potential functions of TEAD4 in UBC.

Materials and Methods

Patients' samples, TCGA-BLCA and multiple GEO datasets were applied to explore the expression pattern of TEAD4 in UBC. Cox regression and Kaplan-Meier survival analyses were carried out to evaluate the prognostic significance of TEAD4 in UBC. Wound healing and transwell assays were performed to explore the biological functions of TEAD4 in UBC cells.

Results

The results of TCGA-BLCA, GEO datasets, Western blotting and immunohistochemistry staining (IHC) indicated that TEAD4 was strikingly elevated in UBC tissues as compared to their normal counterparts, and upregulation of TEAD4 was significantly correlated with clinical stage, pathological grade and poor clinical outcome. Functional studies demonstrated that TEAD4 knockdown suppressed cell migration and invasion by reducing the expression of epithelial-mesenchymal transition (EMT) related markers and transcription regulators.

Conclusion

Our results suggest that TEAD4 may serve as a novel prognostic biomarker and a promising therapeutic target for UBC, and act as a pro-tumorigenic gene to promote cell migration and invasion by inducing EMT.

Relationship Between mir15b and Sal-Like Protein 4 and Biological Behavior of Oral Squamous Cell Carcinoma

miR15b and SALL4 are involved in a variety of tumor progression. The roles of miR15b and SALL4 in oral squamous cell carcinoma (OSCC) remains unclear. The tumors and normal mucosa of OSCC patients were collected to detect miR15b and SALL4 level by Real-time PCR and analyze their correlation with OSCC clinicopathological features. Oral cancer Tca8113 cells were separated into control group; miR15b mimics group and miR15b inhibitor group followed by analysis of SALL4 expression, cell survival by MTT assay; cell invasion by Transwell chamber assay, as well as expression of N-cadherin and Vimentin and correlated with TNM stage, tumor volume and metastasis, and positively with differentiation TGF-β by Western blot. miR15b expression was decreased and SALL4 expression was increased in OSCC tumor tissues. miR15b was negatively degree (P < 0.05), whereas, opposite correlation of SALL4 with the above parameters was found (P < 0.05). miR15b and SALL4 were negatively correlated. MiR15b mimics significantly up-regulated MiR15b, decreased SALL4 expression, inhibited Tca8113 cell proliferation and invasion, as well as reduced N-cadherin, Vimentin and TGF-βexpression (P < 0.05). Opposite results were found in MiR15b inhibitor group. MiR15b expression is decreased and SALL 4 is increased in OSCC tumor tissues. MiR15b and SALL4 is closely related to OSCC clinicopathological features. MiR15b regulates the expression of EMT-related genes and TGF-β, thereby altering the proliferation and invasion of OSCC cells.

Histone chaperone APLF level dictates the implantation of mouse embryos

Our recent findings demonstrated that the histone chaperone and DNA repair factor aprataxin and PNK-like factor (APLF) could regulate epithelial to mesenchymal transition (EMT) during the reprogramming of murine fibroblasts and in breast cancer metastasis. Therefore, we investigated the function of APLF in EMT associated with mouse development. Here, we show that APLF is predominantly enhanced in trophectoderm (TE) and lineages derived from TE in pre- and post-implantation embryos. Downregulation of APLF induced the hatching of embryos in vitro, with a significant increase in Cdh1 and Cdx2 expression. Aplf short hairpin RNA-microinjected embryos failed to implant in vivo Rescue experiments neutralized the knockdown effects of APLF both in vitro and in vivo Reduced expression of Snai2 and Tead4, and the gain in Cdh1 and sFlt1 (also known as Flt1) level, marked the differentiation of APLF-knocked down trophoblast stem cells that might contribute towards the impaired implantation of embryos. Hence, our findings suggest a novel role for APLF during implantation and post-implantation development of mouse embryos. We anticipate that APLF might contribute to the establishment of maternal-fetal connection, as its fine balance is required to achieve implantation and thereby attain proper pregnancy.

Structural and Functional Overview of TEAD4 in Cancer Biology

TEA domain transcription factor 4 (TEAD4) is an important member of the TEAD family. As a downstream effector of the Hippo pathway, TEAD4 has essential roles in cell proliferation, cell survival, tissue regeneration, and stem cell maintenance. TEAD4 contains a TEA DNA binding domain that binds the promoters of target genes and a Yes-associated protein/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) binding domain that associates with transcriptional cofactors. TEAD4 coordinates with YAP, TAZ, VGLL, and other transcription factors to regulate different cellular processes in cancer via its transcriptional output. Moreover, TEAD4 undergoes post-translational modifications and subcellular translocations, and both processes have been shown to shed new insights on how TEAD transcriptional activity can be modified. In summary, TEAD4 has important roles in cancer, including epithelial-mesenchymal transition (EMT), metastasis, cancer stem cell dynamics, and chemotherapeutic drug resistance, suggesting that TEAD4 may be a promising prognostic biomarker in cancer.

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.

Slug Is A Surrogate Marker of Epithelial to Mesenchymal Transition (EMT) in Head and Neck Cancer

Background: Epithelial to mesenchymal transition (EMT) promotes therapy resistance in head and neck cancer (HNC) cells. In this study, EMT was quantified in HNC tumor samples by the cellular co-localization of cytokeratin/vimentin, E-cadherin/β-catenin and by Slug expression. Methods: Tissue samples from HNC patients were stained with antibody pairs against cytokeratin/vimentin and E-cadherin/β-catenin. Epithelial–mesenchymal co-localization was quantified using immunofluorescence multichannel image cytometry. Double positivity was confirmed using confocal microscopy. Slug was semi-quantified by 2 specialists and quantified by bright field image cytometry. Results: Tumor samples of 102 patients were investigated. A loss of E-cadherin positive cells (56.9 ± 2.6% vs. 97.9 ± 1.0%; p < 0.0001) and E-cadherin/β-catenin double positive cells (15.4 ± 5.7% vs. 85.4 ± 1.2%; p < 0.0001) was observed in tumor samples. The percentage of Slug positive cells was increased in tumor samples (12.1 ± 3.6% vs. 3.2 ± 2.6%; p = 0.001). Ordinal Slug scores judged by two specialists closely correlated with percentage of Slug-positive cells (Spearman’s rho = 0.81; p < 0.001). Slug score correlated negatively with the percentage of E-cadherin positive cells (r = 0.4; p = 0.006), the percentage of E-cadherin/β-catenin positive cells (r = 0.5; p = 0.001) and positively with cytokeratin/vimentin positive cells (r = 0.4, p = 0.003). Conclusion: EMT can be assessed in HNC tumor probes by cytokeratin/vimentin co-expression and loss of E-cadherin/β-catenin co-expression. Slug score provides a convenient surrogate marker for EMT.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Hippo 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.

Cordycepin Enhances Radiosensitivity in Oral Squamous Carcinoma Cells by Inducing Autophagy and Apoptosis Through Cell Cycle Arrest

Oral squamous cell carcinoma (OSCC) is one of the most common cancers worldwide and accounts for over 90% of malignant neoplasms of the oral cavity, with a 5-year survival rate of less than 50%. The long-term survival rate of OSCC patients has not markedly improved in recent decades due to its heterogeneous etiology and treatment outcomes. We investigated the anticancer effect of the combination of irradiation (IR) and cordycepin in the treatment of human OSCC cells in vitro. The type of cell death, especially autophagy and apoptosis, and the underlying mechanisms were examined. We found synergistic effects of cordycepin and IR on the viability of human oral cancer cells. The combination of cordycepin and IR treatment induced apoptosis, cell cycle arrest, and autophagic cell death. Furthermore, cordycepin induced S-phase arrest and prolonged G2/M arrest in the cells that received the combination treatment compared with those that received irradiation alone. Combined treatment induced the upregulation of ATG5 and p21 in an autophagy cascade-dependent manner, arrested the cell cycle in the G2/M phase, and repressed cell proliferation. Thus, we conclude that the combination of cordycepin and IR treatment could be a potential therapeutic strategy for OSCC.

The Hippo effector TAZ promotes cancer stemness by transcriptional activation of SOX2 in head neck squamous cell carcinoma

The Hippo-TAZ signaling has emerged as a fundamental regulator underlying cancer stem cells (CSCs) stemness which intricately associates with local recurrence and metastatic spreading in head neck squamous cell carcinoma (HNSCC). However, the precise downstream targets of TAZ responsible for HNSCC CSCs maintenance remain largely underexplored. Here, we identified Sex determining region Y box 2 (SOX2) as a putative downstream target of TAZ to promote CSCs maintenance and tumorigenicity in HNSCC. Both TAZ and SOX2 were significantly enriched in CSCs subpopulation (CD44⁺CD133⁺) isolated from Cal27 and Fadu cells via fluorescence-activated cell sorting. TAZ knockdown significantly reduced expression of SOX2 at both mRNA and protein levels, whereas its ectopic overexpression markedly increased its abundance in HNSCC cells. Moreover, reintroduction of ectopic SOX2 abolished, at least in part, the reduced tumorsphere formation and tumorigenicity in vivo induced by TAZ knockdown. Mechanistically, transcriptional complex formed by TAZ and TEAD4 was recruited to two binding sites in SOX2 promoter, which in turn facilitated transcription of SOX2 in HNSCC cells. In addition, the abundance of TAZ and SOX2 was positively correlated in HNSCC clinical samples, and both upregulations of TAZ and SOX2 associated with the worst survival. Taken together, our data reveal a previously unknown mechanistic linkage between TAZ and SOX2 and identify SOX2 as a direct downstream target of TAZ in modulating CSCs self-renewal and maintenance in HNSCC. These findings suggest that targeting TAZ-SOX2 axis might be a promising therapeutic strategy for HNSCC.

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.