TAZ promotes vasculogenic mimicry in gastric cancer through the upregulation of TEAD4

The role of N6-methyladenosine modification in tumor angiogenesis

Tumor angiogenesis is a characteristics of malignant cancer progression that facilitates cancer cell growth, diffusion and metastasis, and has an indispensable role in cancer development. N6-methyladenosine (m6A) is among the most prevalent internal modifications in eukaryotic RNAs, and has considerable influence on RNA metabolism, including its transcription, splicing, localization, translation, recognition, and degradation. The m6A modification is generated by m6A methyltransferases ("writers"), removed by m6A demethylases ("erasers"), and recognized by m6A-binding proteins ("readers"). There is accumulating evidence that abnormal m6A modification is involved in the pathogenesis of multiple diseases, including cancers, and promotes cancer occurrence, development, and progression through its considerable impact on oncoprotein expression. Furthermore, increasing studies have demonstrated that m6A modification can influence angiogenesis in cancers through multiple pathways to regulate malignant processes. In this review, we elaborate the role of m6A modification in tumor angiogenesis-related molecules and pathways in detail, providing insights into the interactions between m6A and tumor angiogenesis. Moreover, we describe how targeting m6A modification in combination with anti-angiogenesis drugs is expected to be a promising anti-tumor treatment strategy, with potential value for addressing the challenge of drug resistance.

A Role for the Hippo/YAP1 Pathway in the Regulation of In Vitro Vasculogenic Mimicry in Glioblastoma Cells

The Hippo pathway plays a tumorigenic role in highly angiogenic glioblastoma (GBM), whereas little is known about clinically relevant Hippo pathway inhibitors' ability to target adaptive mechanisms involved in GBM chemoresistance. Their molecular impact was investigated here in vitro against an alternative process to tumour angiogenesis termed vasculogenic mimicry (VM) in GBM-derived cell models. In silico analysis of the downstream Hippo signalling members YAP1, TAZ and TEAD1 transcript levels in low-grade glioblastoma (LGG) and GBM tumour tissues was performed using GEPIA. TAZ transcript levels did not differ between the healthy and tumour tissues data analysed. In contrast, YAP1 transcript levels were elevated in GBM tissues, whereas TEAD1 levels were high in both LGG and GBM. All three Hippo pathway inhibitors tested, GNE7883, VT107 and IAG933 effectively inhibited U87 and U251 cell migration and in vitro VM as assessed on Cultrex matrix. YAP1 gene and protein expression were induced upon VM, and its translocation to the nucleus was inhibited by the Hippo pathway inhibitors tested. SiRNA-mediated transient silencing of YAP1 repressed cell migration, VM formation and CTGF and Cyr61 transcription. In conclusion, targeting of VM using Hippo pathway inhibitors could help circumvent GBM chemoresistance and effectively complement other brain cancer treatments.

Transcriptional regulation of CYR61 and CTGF by LM98: a synthetic YAP-TEAD inhibitor that targets in-vitro vasculogenic mimicry in glioblastoma cells

Glioblastoma (GBM) is a highly angiogenic malignancy of the central nervous system that resists standard antiangiogenic therapy, in part because of an alternative process to angiogenesis termed vasculogenic mimicry. Intricately linked to GBM, dysregulation of the Hippo signaling pathway leads to overexpression of YAP/TEAD and several downstream effectors involved in therapy resistance. Little is known about whether vasculogenic mimicry and the Hippo pathway intersect in the GBM chemoresistance phenotype. This study seeks to investigate the expression patterns of Hippo pathway regulators within clinically annotated GBM samples, examining their involvement in vitro regarding vasculogenic mimicry. In addition, it aims to assess the potential for pharmacological targeting of this pathway. In-silico analysis of the Hippo signaling members YAP1 , TEAD1 , AXL , NF2 , CTGF , and CYR61 transcript levels in low-grade GBM and GBM tumor tissues was done by Gene Expression Profiling Interactive Analysis. Gene expression was analyzed by real-time quantitative PCR from human U87, U118, U138, and U251 brain cancer cell lines and in clinically annotated brain tumor cDNA arrays. Transient gene silencing was performed with specific small interfering RNA. Vasculogenic mimicry was assessed using a Cultrex matrix, and three-dimensional capillary-like structures were analyzed with Wimasis. CYR61 and CTGF transcript levels were elevated in GBM tissues and were further induced when in-vitro vasculogenic mimicry was assessed. Silencing of CYR61 and CTGF , or treatment with a small-molecule TEAD inhibitor LM98 derived from flufenamic acid, inhibited vasculogenic mimicry. Silencing of SNAI1 and FOXC2 also altered vasculogenic mimicry and reduced CYR61 / CTGF levels. Pharmacological targeting of the Hippo pathway inhibits in-vitro vasculogenic mimicry. Unraveling the connections between the Hippo pathway and vasculogenic mimicry may pave the way for innovative therapeutic strategies.

Notch1 signaling pathway promotes growth and metastasis of gastric cancer via modulating CDH5

OBJECTIVE

To explore the underlying molecular mechanism of Notch1/cadherin 5 (CDH5) pathway in modulating in cell malignant behaviors of gastric cancer (GC).

METHODS

We performed bioinformatic analyses to screen the potential target genes of Notch1 from cadherins in GC. Western blot and RT-PCR were conducted to detect CDH5 expression in GC tissues and cells. We utilized chromatin immunoprecipitation (CHIP) assays to assess the interaction of Notch1 with CDH5 gene. The effects of Notch1/CDH5 axis on the proliferation, invasion, migration and vasculogenic mimicry in GC cells were evaluated by EdU, wound healing, transwell, and tubule formation assays.

RESULTS

Significantly increased CDH5 expression was found in GC tissues compared with paracancerous tissues and associated to clinical stage and poor overall survival (OS) in patients with GC. Notch1 positively regulate the expression of CDH5 in GC cells. CHIP assays validated that CDH5 was a direct target of Notch1. In addition, Notch1 upregulation enhanced the proliferation, migration, invasion and vasculogenic mimicry capacity of GC cells, which could be attenuated by CDH5 silencing.

CONCLUSIONS

These results indicated Notch1 upregulation enhanced GC malignant behaviors by triggering CDH5, suggesting that targeting Notch1/CDH5 axis could be a potential therapeutic strategy for GC progression.

Inhibition of Connective Tissue Growth Factor Expression in Adult Retinal Pigment Epithelial-19 Cells by Blocking Yes-Associated Protein/Transcriptional Coactivator with PDZ-Binding Motif Activity

Purpose: To investigate the effect of yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) on connective tissue growth factor (CTGF) expression in adult retinal pigment epithelial (ARPE)-19 cells. We also studied the inhibitory effect of K-975, a new pan-transcriptional enhanced associate domain (TEAD) inhibitor, and luteolin, a plant-derived flavonoid on CTGF expression. Methods: ARPE-19 cells were transfected with either YAP or TAZ overexpression plasmid or treated with transforming growth factor (TGF)-β2. The cells were cultured either with or without K-975 or luteolin. The expression of YAP, TAZ, and CTGF was examined using real-time PCR. Results: ARPE-19 cells overexpressing YAP or TAZ exhibited significantly increased CTGF expression. This increase was attenuated by K-975 or luteolin alone. TGF-β2 treatment significantly raised the expression of not just YAP and TAZ, but also CTGF in ARPE-19 cells. TGF-β2 treatment-enhanced CTGF expression was considerably lowered by the addition of K-975 or luteolin. Conclusions: Overexpression of YAP or TAZ and treatment with TGF-β2 led to an increase in the expression of CTGF in ARPE-19 cells. These increases were attenuated by treatment with K-975 and luteolin. These findings suggest that YAP and TAZ may be related to the expression of CTGF in ARPE-19 cells and that K-975 and luteolin can be explored as potential therapeutic agents for preventing CTGF production in vitreoretinal fibrosis.

GPR137 inactivates Hippo signaling to promote gastric cancer cell malignancy

As the fifth most common cancer in the world, gastric cancer (GC) ranks as the third major cause of cancer-related death globally. Although surgical resection and chemotherapy still remains the mainstay of potentially curative treatment for GC, chemotherapy resistance and adverse side effects limit their clinical applications. Thus, further investigation of the mechanisms of carcinogenesis in GC and discovery of novel biomarkers is of great concern. We herein report that the elevated expression of GPR137 is correlated with GC. Overexpression of GPR137 potentiates human gastric cancer AGS cell malignancy, including proliferation, migration, invasion, colony formation and xenograft growth in nude mice in vivo, whereas knockout of GPR137 by CRISPR/Cas9 gene editing exerts the opposite effects. Mechanistically, GPR137 could bind to MST, the upstream kinases in Hippo pathway, which disrupts the association of MST with LATS, subsequently activating the transcriptional co-activators, YAP and TAZ, and thereby triggering the target transcription and the alterations in GC cell biological actions consequently. Therefore, our findings may provide with the evidence of developing a potentially novel treatment method with specific target for GC.

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.

PSMA1 mediates tumor progression and poor prognosis of gastric carcinoma by deubiquitinating and stabilizing TAZ

The deubiquitinating enzyme family in tumor progression play important role in intracellular protein degradation. The proteasome subunit alpha type 1 (PSMA1) has been reported to act as an oncogene in several human cancers. The present study aimed to reveal the functional significance of PSMA1 in gastric cancer (GC) progression and the underlying mechanisms. The expression of PSMA1 in human GC samples and GC cell lines was examined by western blot analysis, real-time PCR, immunohistochemistry (IHC), and in vitro ubiquitination assays and established a xenograft mouse model. We found that PSMA1 was upregulated in GC and promoted proliferation, migration and invasion in GC cells. Herein, we report transcriptional co-activator with PDZ-binding motif (TAZ) was a downstream gene of PSMA1. Mechanistically, PSMA1 directly interacted with and stabilized TAZ via deubiquitination in GC. Furthermore, we found that TAZ was the essential mediator of PSMA1-modulated oncogenic activity in vitro and in vivo. Examination of clinical samples confirmed that elevated mediators of PSMA1, concomitant with increased TAZ abundance, correlate with human GC progression. These data suggested that PSMA1 promotes GC progression and proliferation by deubiquitinating TAZ. PSMA1 promotes GC progression and proliferation regarding PSMA1-mediated deubiquitinating enzyme activity and suggest potential therapeutic targets for GC management.

Targeting the Hippo Pathway in Gastric Cancer and Other Malignancies in the Digestive System: From Bench to Bedside

The Hippo pathway is an evolutionally conserved signaling cascade that controls organ size and tissue regeneration under physiological conditions, and its aberrations have been well studied to promote tumor initiation and progression. Dysregulation of the Hippo tumor suppressor signaling frequently occurs in gastric cancer (GC) and other solid tumors and contributes to cancer development through modulating multiple aspects, including cell proliferation, survival, metastasis, and oncotherapy resistance. In the clinic, Hippo components also possess diagnostic and prognostic values for cancer patients. Considering its crucial role in driving tumorigenesis, targeting the Hippo pathway may greatly benefit developing novel cancer therapies. This review summarizes the current research progress regarding the core components and regulation of the Hippo pathway, as well as the mechanism and functional roles of their dysregulation in gastrointestinal malignancies, especially in GC, and discusses the therapeutic potential of targeting the Hippo pathway against cancers.

Recent insight into the role and therapeutic potential of YAP/TAZ in gastrointestinal cancers

With the rapid development of cancer treatment, gastrointestinal (GI) cancers are still the most prevalent malignancies with high morbidity and mortality worldwide. Dysregulation of the Hippo signaling pathway has been recognized to play a critical role during cancer development and adopted for monitoring disease progression and therapy response. Despite the well-documented tumor proliferation and metastasis, recent efforts in two core Hippo components, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), have identified as the driving forces behind cancer metabolism, stemness, tumor immunity, and therapy resistance. Understanding the molecular mechanisms by which YAP/TAZ facilitates the tumorigenesis and progression of GI cancer, and identifying novel therapeutic strategies for targeting YAP/TAZ are crucial to GI cancer treatment and prevention. In this study, we summarize the latest findings on the function and regulatory mechanisms of YAP/TAZ in GI cancers, and highlight the translational significance of targeting YAP/TAZ for cancer therapies.