WNK1 Interaction with KEAP1 Promotes NRF2 Stabilization to Enhance the Oxidative Stress Response in Hepatocellular Carcinoma.

Cellular oxidative stress plays a key role in the development and progression of hepatocellular carcinoma (HCC). A better understanding of the processes that regulate reactive oxygen species (ROS) homeostasis could uncover improved strategies for treating HCC. Here, we identified WNK1 as an antioxidative factor and therapeutic target in HCC. In human HCC, WNK1 expression was increased and correlated with poor patient prognosis. WNK1 knockdown significantly inhibited cell proliferation and xenograft tumor growth. Mechanistically, WNK1 competed with NRF2 for binding to the partial Kelch domain of KEAP1, reducing NRF2 ubiquitination and promoting NRF2 accumulation and nuclear translocation to increase antioxidant response. WNK1 silencing increased H2O2-induced apoptosis and inhibited cell growth by elevating reactive oxygen species (ROS) levels, which could be rescued by treatment with the antioxidant N-acetylcysteine (NAC) and NRF2 activator tert-butylhydroquinone (tBHQ). Liver-specific WNK1 knockout mouse models of HCC substantiated that WNK1 promoted HCC development by regulating ROS levels. WNK463, an inhibitor of the WNK kinase family, suppressed HCC progression and altered the redox status. These findings suggest that WNK1 plays a critical role in HCC development and progression and that the WNK1-oxidative stress axis may be a promising therapeutic target for HCC.

Exploring the prognostic analysis of autophagy and tumor microenvironment based on monocyte cells in lung cancer.

A deep understanding of the biological mechanisms of lung cancer offers more precise treatment options for patients. In our study, we integrated data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) to investigate lung adenocarcinoma. Analyzing 538 lung cancer samples and 31 normal samples, we focused on 3076 autophagy-related genes. Using Seurat, dplyr, tidyverse, and ggplot2, we conducted single-cell data analysis, assessing the quality and performing Principal Component Analysis (PCA) and t-SNE analyses. Differential analysis of TCGA data using the "Limma" package, followed by immune infiltration analysis using the CIBERSORT algorithm, led us to identify seven key genes. These genes underwent further scrutiny through consensus clustering and gene set variation analysis (GSVA). We developed a prognostic model using Lasso Cox regression and multivariable Cox analysis, which was then validated with a nomogram, predicting survival rates for lung adenocarcinoma. The model's accuracy and universality were corroborated by ROC curves. Additionally, we explored the relationship between immune checkpoint genes and immune cell infiltration and identified two key genes, HLA-DQB1 and OLR1. This highlighted their potential as therapeutic targets. Our comprehensive approach sheds light on the molecular landscape of lung adenocarcinoma and offers insights into potential treatment strategies, emphasizing the importance of integrating single-cell and genomic data in cancer research.

The emerging landscape of exosomal CircRNAs in solid cancers and hematological malignancies.

Circular RNAs (circRNAs) are a type of recently discovered noncoding RNA. They exert their biological functions by competitively binding to microRNAs (miRNAs) as miRNA sponges, promoting gene transcription and participating in the regulation of selective splicing, interacting with proteins and being translated into proteins. Exosomes are derived from intracavitary vesicles (ILVs), which are formed by the inward budding of multivesicular bodies (MVBs), and exosome release plays a pivotal role in intercellular communication. Accumulating evidence indicates that circRNAs in exosomes are associated with solid tumor invasion and metastasis. Additionally, emerging studies in the last 1 ~ 2 years have revealed that exosomal circRNA also have effect on hematological malignancies. In this review, we outline the properties and biological functions of circRNAs and exosomes. In particular, we summarize in detail the mechanism and roles of exosomal circRNAs and highlight their application as novel biomarkers in malignant tumors.

Novel Insights Into MALAT1 Function as a MicroRNA Sponge in NSCLC.

The long non-coding RNA metastasis-associated lung adenocarcinoma transcript-1 (MALAT1) was initially found to be overexpressed in early non-small cell lung cancer (NSCLC). Accumulating studies have shown that MALAT1 is overexpressed in the tissue or serum of NSCLC and plays a key role in its occurrence and development. In addition, the expression level of MALAT1 is significantly related to the tumor size, stage, metastasis, and distant invasion of NSCLC. Therefore, MALAT1 could be used as a biomarker for the early diagnosis, severity assessment, or prognosis evaluation of NSCLC patients. This review describes the basic properties and biological functions of MALAT1, focuses on the specific molecular mechanism of MALAT1 as a microRNA sponge in the occurrence and development of NSCLC in recent years, and emphasizes the application and potential prospect of MALAT1 in molecular biological markers and targeted therapy of NSCLC.

Case Report: Abscopal Effect of Microwave Ablation in a Patient With Advanced Squamous NSCLC and Resistance to Immunotherapy.

Currently, immunotherapy has been a backbone in the treatment of advanced non-small cell lung cancer (NSCLC) without driver gene mutations. However, only a small proportion of NSCLC patients respond to immune checkpoint inhibitors, and majority of patients with initial response will develop acquired resistance at 5 years, which usually manifests as oligo-progression or oligo-metastases. Evidence from multiple clinical trials indicates that local consolidative therapies could improve the prognosis of oligometastatic NSCLC patients. Herein, we reported a case of advanced squamous lung cancer which showed a durable abscopal effect from microwave ablation after acquired resistance of immunotherapy.

The FOXM1/ATX signaling contributes to pancreatic cancer development.

Both autotaxin (ATX) and Forkhead Box M1 (FOXM1) have been commonly recognized as oncogenes in multiple types of human malignancies. However, the expression and biological functions of ATX in pancreatic ductal adenocarcinoma (PDAC), and its correlation with FOXM1 are poorly understood. The present study aimed to investigate their correlation and biological consequences in PDAC development. By dual luciferase reporter and chromatin immunoprecipitation assays, we found that ATX was a downstream transcriptional target gene of FOXM1. Further cellular functional experiments indicated that ATX was required for FOXM1-mediated PDAC cell proliferation and migration. Data from molecular biological experiments showed that ATX could enhance FOXM1 expression in turn by inhibiting the Hippo signaling pathway, suggesting that ATX and FOXM1 formed a positive feedback loop to facilitate PDAC progression. Using immunohistochemistry (IHC) method, both ATX and FOXM1 expression were found to be frequently up-regulated in PDAC tumor tissues when compared with adjacent normal tissues, and elevated ATX and FOXM1 expression were positively correlated with each other. In conclusion, the present work identified a positive feedback loop between ATX and FOXM1 which promotes PDAC cell proliferation and migration.

Methylation of HSP70 Orchestrates Its Binding to and Stabilization of BCL2 mRNA and Renders Pancreatic Cancer Cells Resistant to Therapeutics.

Pancreatic cancer is a lethal disease owing to its intrinsic and acquired resistance to therapeutic modalities. The altered balance between pro- and antiapoptosis signals within cancer cells is critical to therapeutic resistance. However, the molecular mechanisms underlying increased antiapoptosis signals remain poorly understood. In this study, we report that PRMT1 expression is increased in pancreatic cancer tissues and is associated with higher tumor grade, increased aggressiveness, and worse prognosis. PRMT1 overexpression increased arginine methylation of HSPs of 70 kDa (HSP70); this methylation enhanced HSP70 binding and stabilization of BCL2 mRNA through AU-rich elements in 3'-untranslated region and consequentially increased BCL2 protein expression and protected cancer cells from apoptosis induced by cellular stresses and therapeutics. RNA binding and regulation function of HSP70 was involved in pancreatic cancer drug resistance and was dependent on protein arginine methylation. These findings not only reveal a novel PRMT1-HSP70-BCL2 signaling axis that is crucial to pancreatic cancer cell survival and therapeutic resistance, but they also provide a proof of concept that targeted inhibition of this axis may represent a new therapeutic strategy. SIGNIFICANCE: This study demonstrates that a PRMT1-mediated stabilization of BCL2 mRNA contributes to therapeutic resistance in pancreatic cancer and that targeting this pathway could overcome said resistance.

A novel KDM5A/MPC-1 signaling pathway promotes pancreatic cancer progression via redirecting mitochondrial pyruvate metabolism.

Mitochondrial pyruvate carrier 1 (MPC-1) appears to be a tumor suppressor. In this study, we determined the regulation of MPC-1 expression by Lysine demethylase 5A (KDM5A) and critical impact of this novel KDM5A/MPC-1 signaling on PDA progression. TCGA database, paired PDA and adjacent normal pancreatic tissues, PDA tissue array and cell lines were used to determine the levels of MPC-1 and KDM5A expression, and their relationship with the clinicopathologic characteristics and overall survival (OS) of PDA patients. Both in vitro and in vivo models were used to determine biologic impacts of MPC-1 and KDM5A on PDA and mitochondrial pyruvate metabolism, and the mechanism underling reduced MPC-1 expression in PDA. The expression of MPC-1 was decreased in PDA cell lines and tissues, and negatively associated with tumor poorer differentiation, lymph nodes metastasis, higher TNM stages, and patients' overall survival (OS). Functional analysis revealed that restored expression of MPC-1 suppressed the growth, invasion, migration, stemness and tumorigenicity. Re-expression of MPC-1 stimulated the mitochondrial pyruvate metabolism and inhibited glycolysis, while MPC-1-specific inhibitor UK5099 attenuated these effects. Furthermore, KDM5A bound directly to MPC-1 promoter region and transcriptionally suppressed the expression of MPC-1 via demethylation H3K4. Consistently, KDM5A expression was elevated in PDA and promoted PDA cell proliferation in vitro and tumor growth in vivo via suppressing the expression of MPC-1. The expression of KDM5A was inversely correlated with that of MPC-1 in PDA. KDM5A/MPC-1 signaling promoted PDA growth, invasion, migration, and stemness via inhibiting mitochondrial pyruvate metabolism. Targeting KDM5A/MPC-1 signaling may be an effective therapeutic strategy for PDA.

Pancreatic Acinar-to-Ductal Metaplasia and Pancreatic Cancer.

Acinar-to-ductal metaplasia (ADM) of the pancreas is a process that pancreatic acinar cells differentiate into ductal-like cells with ductal cell traits. The metaplasia of pancreatic acinar cells manifests their ability to adapt to the genetic and environmental pressure they encounter. However, with oncogenic genetic insults and/or sustained environmental stress, ADM may lead to pancreatic intraepithelial neoplasia (PanIN), which is a common precancerous lesion that precedes pancreatic cancer. Understanding the intermediate states of ADM and important molecules that regulate ADM formation may help the development of novel preventive strategies that could be translated to the clinic to benefit the people with high risk of pancreatic cancer. Mouse model is widely used in both in vivo and ex vivo studies of ADM. In this chapter, we describe detailed protocols of injury models of the adult mouse pancreas that can function as a tool to study mechanisms of ADM formation.

The FOXC1/FBP1 signaling axis promotes colorectal cancer proliferation by enhancing the Warburg effect.

Aberrant expression of Forkhead box (FOX) transcription factors plays vital roles in carcinogenesis. However, the function of the FOX family member FOXC1 in maintenance of colorectal cancer (CRC) malignancy is unknown. Herein, FOXC1 expression in CRC specimens in The Cancer Genome Atlas (TCGA) cohort was analyzed and validated using immunohistochemistry with a tissue microarray. The effect of FOXC1 expression on proliferation of and glycolysis in CRC cells was assessed by altering its expression in vitro and in vivo. Mechanistic investigation was carried out using cell and molecular biological approaches. Our results showed that FOXC1 expression was higher in CRC specimens than in adjacent benign tissue specimens. Univariate survival analyses of the patients from whom the study specimens were obtained, and validated cohorts indicated that ectopic FOXC1 expression was significantly correlated with shortened survival. Silencing FOXC1 expression in CRC cells inhibited their proliferation and colony formation and decreased their glucose consumption and lactate production. In contrast, FOXC1 overexpression had the opposite effect. Furthermore, increased expression of FOXC1 downregulated that of a key glycolytic enzyme, fructose-1,6-bisphosphatase 1 (FBP1). Mechanistically, FOXC1 bound directly to the promoter regions of the FBP1 gene and negatively regulated its transcriptional activity. Collectively, aberrant FBP1 expression contributed to CRC tumorigenicity, and decreased FBP1 expression coupled with increased FOXC1 expression provided better prognostic information than did FOXC1 expression alone. Therefore, the FOXC1/FBP1 axis induces CRC cell proliferation, reprograms metabolism in CRCs, and constitutes potential prognostic predictors and therapeutic targets for CRC.

Correction: ZFPM2-AS1, a novel lncRNA, attenuates the p53 pathway and promotes gastric carcinogenesis by stabilizing MIF.

Since the online publication of the above article, the authors have noted errors in the affiliations. The authors apologise for any inconvenience caused by this error. The html and online pdf versions have now been rectified and carry the corrected paper.

ZFPM2-AS1, a novel lncRNA, attenuates the p53 pathway and promotes gastric carcinogenesis by stabilizing MIF.

Long non-coding RNAs (lncRNAs) are implicated to be involved in the pathogenesis of many cancers. Herein we report on our discovery of a novel lncRNA, ZFPM2 antisense RNA 1 (ZFPM2-AS1), and its critical role in gastric carcinogenesis. ZFPM2-AS1 expression in gastric cancer specimens was analyzed using Gene Expression Omnibus data set and validated in 73 paired gastric tumor and normal adjacent gastric tissue specimens using qRT-PCR. The effect of ZFPM2-AS1 expression on proliferation and apoptosis in gastric cancer cells was assessed by altering its expression in vitro and in vivo. Mechanistic investigation was carried out using cell and molecular biological approaches. ZFPM2-AS1 expression was higher in gastric tumors than in normal gastric tissue. Also, increased ZFPM2-AS1 expression in gastric cancer specimens was associated with tumor size, depth of tumor invasion, differentiation grade, and TNM stage. High ZFPM2-AS1 expression predicted markedly reduced overall and disease-free survival in gastric cancer patients. Functional experiments demonstrated that ZFPM2-AS1 expression promoted proliferation and suppressed apoptosis of gastric cancer cells in vitro and promoted tumor growth in vivo. This effect is associated with attenuated nuclear translocation of p53. Mechanistic experiments demonstrated that tumor-activated ZFPM2-AS1 could bind to and protect the degradation of macrophage migration inhibitory factor (MIF), a potent destabilizer of p53. Knockdown of MIF expression diminished ZFPM2-AS1's impact on p53 expression in gastric cancer cells. Our findings demonstrated that ZFPM2-AS1 regulates gastric cancer progression and revealed a novel ZFPM2-AS1/MIF/p53 signaling axis, shedding light on the molecular mechanisms underlying the tumorigenicity of certain malignant gastric cells.

Krüppel-like Factor 4 Suppresses Serine/Threonine Kinase 33 Activation and Metastasis of Gastric Cancer through Reversing Epithelial-Mesenchymal Transition.

Background: Cancers with aberrant expression of Serine/threonine kinase 33 (STK33) has been reported to be particularly aggressive. However, its expression, clinical significance, and biological functions in gastric cancer remain largely unknown. In the present study, we determined the expression and function of STK33 in gastric cancer and delineated the clinical significance of the Krüppel-like factor 4 (KLF4)/STK33 signaling pathway.Methods: STK33 expression and its association with multiple clinicopathologic characteristics were analyzed immunohistochemically in human gastric cancer specimens. STK33 knockdown and overexpression were used to dissect the underlying mechanism of its functions in gastric cancer cells. Regulation and underlying mechanisms of STK33 expression by KLF4 in gastric cancer cells were studied using cell and molecular biological methods.Results: Drastically higher expression of STK33 was observed in gastric cancer and gastric intraepithelial neoplasia tissues compared with adjacent normal gastric tissues. Increased STK33 expression correlated directly with tumor size, lymph node, and distant metastasis; and patients with low STK33 expression gastric cancer were predicted to have a favorable prognosis. Enforced expression of STK33 promoted gastric cancer cell proliferation, migration, and invasion in vitro and in vivo, whereas reduced STK33 did the opposite. Moreover, STK33 promoted epithelial-mesenchymal transition (EMT) in vitro Mechanistically, KLF4 transcriptionally inhibited STK33 expression in gastric cancer cells. KLF4-mediated inhibition of gastric cancer cell invasion was reversed by upregulation of STK33 expression.Conclusions: STK33 has pro-tumor function and is a critical downstream mediator of KLF4 in gastric cancer. STK33 may serve as a potential prognostic marker and therapeutic target for gastric cancer. Clin Cancer Res; 24(10); 2440-51. ©2018 AACR.

STK33 Promotes Growth and Progression of Pancreatic Cancer as a Critical Downstream Mediator of HIF1α.

The serine/threonine kinase STK33 has been implicated in cancer cell proliferation. Here, we provide evidence of a critical role for STK33 in the pathogenesis and metastatic progression of pancreatic ductal adenocarcinoma (PDAC). STK33 expression in PDAC was regulated by the hypoxia-inducible transcription factor HIF1α. In human PDAC specimens, STK33 was overexpressed and associated with poor prognosis. Enforced STK33 expression promoted PDAC proliferation, migration, invasion, and tumor growth, whereas STK33 depletion exerted opposing effects. Mechanistic investigations showed that HIF1α regulated STK33 via direct binding to a hypoxia response element in its promoter. In showing that dysregulated HIF1α/STK33 signaling promotes PDAC growth and progression, our results suggest STK33 as a candidate therapeutic target to improve PDAC treatment. Cancer Res; 77(24); 6851-62. ©2017 AACR.

DNA-Methyltransferase 1 Induces Dedifferentiation of Pancreatic Cancer Cells through Silencing of Krüppel-Like Factor 4 Expression.

Purpose: The dismal prognosis of pancreatic cancer has been linked to poor tumor differentiation. However, molecular basis of pancreatic cancer differentiation and potential therapeutic value of the underlying molecules remain unknown. We investigated the mechanistic underexpression of Krüppel-like factor 4 (KLF4) in pancreatic cancer and defined a novel epigenetic pathway of its activation for pancreatic cancer differentiation and treatment.Experimental Design: Expressions of KLF4 and DNMT1 in pancreatic cancer tissues were determined by IHC and the genetic and epigenetic alterations of KLF4 in and KLF4's impact on differentiation of pancreatic cancer were examined using molecular biology techniques. The function of dietary 3,3'-diindolylmethane (DIM) on miR-152/DNMT1/KLF4 signaling in pancreatic cancer was evaluated using both cell culture and animal models.Results: Overexpression of DNMT1 and promoter hypermethylation contributed to decreased KLF4 expression in and associated with poor differentiation of pancreatic cancer. Manipulation of KLF4 expression significantly affected differentiation marker expressions in pancreatic cancer cells. DIM treatment significantly induced miR-152 expression, which blocked DNMT1 protein expression and its binding to KLF4 promoter region, and consequently reduced promoter DNA methylation and activated KLF4 expression in pancreatic cancer cells. In addition, DIM treatment caused significant inhibition of cell growth in vitro and tumorigenesis in animal models of pancreatic cancer.Conclusions: This is the first demonstration that dysregulated KLF4 expression associates with poor differentiation of pancreatic cancer. Epigenetic activation of miR-152/DNMT1/KLF4 signaling pathway by dietary DIM causes differentiation and significant growth inhibition of pancreatic cancer cells, highlighting its translational implications for pancreatic and other cancers. Clin Cancer Res; 23(18); 5585-97. ©2017 AACR.

The Novel KLF4/MSI2 Signaling Pathway Regulates Growth and Metastasis of Pancreatic Cancer.

PURPOSE: Musashi 2 (MSI2) is reported to be a potential oncoprotein in cases of leukemia and several solid tumors. However, its expression, function, and regulation in pancreatic ductal adenocarcinoma (PDAC) cases have yet to be demonstrated. Therefore, in the current study, we investigated the clinical significance and biologic effects of MSI2 expression in PDAC cases and sought to delineate the clinical significance of the newly identified Krüppel-like factor 4 (KLF4)/MSI2 regulatory pathway. EXPERIMENTAL DESIGN: MSI2 expression and its association with multiple clinicopathologic characteristics in human PDAC specimens were analyzed immunohistochemically. The biological functions of MSI2 regarding PDAC cell growth, migration, invasion, and metastasis were studied using gain- and loss-of-function assays both in vitro and in vivo Regulation of MSI2 expression by KLF4 was examined in several cancer cell lines, and the underlying mechanisms were studied using molecular biologic methods. RESULTS: MSI2 expression was markedly increased in both PDAC cell lines and human PDAC specimens, and high MSI2 expression was associated with poor prognosis for PDAC. Forced MSI2 expression promoted PDAC proliferation, migration, and invasion in vitro and growth and metastasis in vivo, whereas knockdown of MSI2 expression did the opposite. Transcriptional inhibition of MSI2 expression by KLF4 occurred in multiple PDAC cell lines as well as mouse models of PDAC. CONCLUSIONS: Lost expression of KLF4, a transcriptional repressor of MSI2 results in overexpression of MSI2 in PDACs, which may be a biomarker for accurate prognosis. A dysregulated KLF4/MSI2 signaling pathway promotes PDAC progression and metastasis. Clin Cancer Res; 23(3); 687-96. ©2016 AACR.

Krüppel-like Factor 4 Blocks Hepatocellular Carcinoma Dedifferentiation and Progression through Activation of Hepatocyte Nuclear Factor-6.

PURPOSE: Tumor differentiation is a behavioral index for hepatocellular carcinoma (HCC) and a prognostic factor for patients with HCC who undergo orthotopic liver transplantation (OLT). However, the molecular basis for HCC differentiation and prognostic value of the underlying molecules that regulate HCC differentiation are unclear. In this study, we defined a potential driver pathway for HCC differentiation and prognostication. EXPERIMENTAL DESIGN: The regulation and function of Krüppel-like factor 4 (KLF4) and hepatocyte nuclear factor-6 (HNF-6) in HCC differentiation was evaluated using human tissues, molecular and cell biology, and animal models, and its prognostic significance was determined according to its impact on patient survival. RESULTS: There was a direct relationship between the expression levels of KLF4 and HNF6 in HCC. Reduced KLF4 or HNF6 expression correlated with high HCC grade. Poorly differentiated HCC cells had lower expression of KLF4 or HNF6 and differentiation-associated markers than did well-differentiated cells. Elevated KLF4 of HNF6 expression induced differentiation of poorly differentiated hepatoma cells. Mechanistically, KLF4 trans-activated HNF-6 expression. Restored HNF-6 expression upregulated expression of differentiation-associated markers and inhibited HCC cell migration and invasion, whereas HNF-6 knockdown did the opposite. Loss of KLF4 expression in primary HCC correlated with reduced overall survival and shortened relapse-free survival durations after OLT. Combination of KLF4 expression and the Milan criteria improved prognostication for HCC after OLT. CONCLUSIONS: The dysregulated KLF4/HNF-6 pathway drives dedifferentition and progression of HCC, and KLF4 is a biomarker for accurate prognostication of patients with HCC treated by OLT when integrated with the Milan Criteria.

Elevated JMJD1A is a novel predictor for prognosis and a potential therapeutic target for gastric cancer.

Jumonji domain-containing protein 1A (JMJD1A) play a key role in the development and progression of several malignancies. The present study investigated the expression and clinical significance of JMJD1A in gastric cancer. JMJD1A was found to be upregulated in gastric cancer tissues and cell lines. Furthermore, the upregulated expression of JMJD1A was significantly correlated with the results of the invasion depth (P=0.006), lymph node metastatic status (P<0.001), and TNM stage (P<0.001). JMJD1A was also shown to be an independent prognostic predictor of overall survival (HR3.988; 95% CI 1.948-8.167; P<0.001) for patients with gastric cancer. In addition, in vitro experiment revealed that knockdown of JMJD1A expression inhibited the gastric cancer cell proliferation, and further study suggested that JMJD1A knockdown suppressed MAPK pathway via transcriptional downregulation the expression of long noncoding RNA MALAT1. Therefore, we speculated that JMJD1A-MALAT1-MAPK signaling might participate in the JMJD1A-induced cell proliferation of gastric cancer. Collectively, our data demonstrate for the first time that JMJD1A gene has an important regulatory role in gastric carcinogenesis, and could function as a novel prognostic indicator and a potential therapeutic target for gastric cancer.

Merlin/NF2 Suppresses Pancreatic Tumor Growth and Metastasis by Attenuating the FOXM1-Mediated Wnt/ß-Catenin Signaling.

Merlin, the protein encoded by the NF2 gene, is a member of the band 4.1 family of cytoskeleton-associated proteins and functions as a tumor suppressor for many types of cancer. However, the roles and mechanism of Merlin expression in pancreatic cancer have remained unclear. In this study, we sought to determine the impact of Merlin expression on pancreatic cancer development and progression using human tissue specimens, cell lines, and animal models. Decreased expression of Merlin was pronounced in human pancreatic tumors and cancer cell lines. Functional analysis revealed that restored expression of Merlin inhibited pancreatic tumor growth and metastasis in vitro and in vivo. Furthermore, Merlin suppressed the expression of Wnt/ß-catenin signaling downstream genes and the nuclear expression of ß-catenin protein, and overexpression of Forkhead box M1 (FOXM1) attenuated the suppressive effect of Merlin on Wnt/ß-catenin signaling. Mechanistically, Merlin decreased the stability of FOXM1 protein, which plays critical roles in nuclear translocation of ß-catenin. Collectively, these findings demonstrated that Merlin critically regulated pancreatic cancer pathogenesis by suppressing FOXM1/ß-catenin signaling, suggesting that targeting novel Merlin/FOXM1/ß-catenin signaling is an effective therapeutic strategy for pancreatic cancer.

Hippo transducer TAZ promotes epithelial mesenchymal transition and supports pancreatic cancer progression.

Transcriptional co-activator with PDZ binding motif (TAZ) is a transducer of the Hippo pathway and promotes cancer development and progression. In the present study, we sought to determine the roles and underlying mechanisms of elevated expression and activation of TAZ in pancreatic cancer development and progression. The mechanistic role of TAZ and Hippo signaling in promotion of pancreatic cancer development and progression was examined using cell culture, molecular biology, and mouse models. The relevance of our experimental and mechanistic findings was validated using human pancreatic tumor specimens. We found that TAZ expression was markedly higher in pancreatic tumors than in normal pancreatic tissue. Further analysis of the correlation of TAZ expression with tissue microarray clinicopathologic parameters revealed that this expression was positively associated with tumor differentiation. Also, TAZ expression was higher in pancreatic cancer cell lines than in pancreatic ductal epithelial cells. TAZ activation in pancreatic cancer cells promoted their proliferation, migration, invasion, and epithelial-mesenchymal transition. Further mechanistic studies demonstrated that aberrant expression and activation of TAZ in pancreatic cancer cells resulted from suppression of the expression of Merlin, a positive regulator upstream of the Hippo pathway, and that the oncogenic function of TAZ in pancreatic cancer cells was mediated by TEA/ATTS domain transcription factors. Therefore, TAZ functioned as an oncogene and promoted pancreatic cancer epithelial-mesenchymal transition and progression. TAZ thus may be a target for effective therapeutic strategies for pancreatic cancer.