Rho kinase phosphorylation promotes ezrin-mediated metastasis in hepatocellular carcinoma

GSE1 promotes the proliferation and migration of lung adenocarcinoma cells by downregulating KLF6 expression

Lung cancer is one of the most prevalent human cancers with a high lethality rate worldwide. In this study, we demonstrated that GSE1 (genetic suppressor element 1) expression is aberrantly upregulated in lung adenocarcinoma and that GSE1 depletion inhibits the proliferation and migration of both A549 and H1299 cells. Immunoprecipitation assays demonstrated that GSE1 interacts with histone deacetylase 1 (HDAC1) and other BRAF-HDAC complex (BHC) components in cells. The transcriptome of GSE1-knockdown A549 cells indicated that 207 genes were upregulated and 159 were downregulated based on a p-value < .05 and fold change ≥ 1.5. Bioinformatics analysis suggested that 140 differentially expressed genes harbor binding sites for HDAC1, including the tumor suppressor gene KLF6 (Kruppel-like factor 6). Indeed, quantitative reverse-transcription polymerase chain reaction and western blot analysis revealed that GSE1 could inhibit the transcription of KLF6 in lung cancer cells. In conclusion, GSE1 cooperates with HDAC1 to promote the proliferation and metastasis of non-small cell lung cancer cells through the downregulation of KLF6 expression.

Genomic and transcriptomic profiling reveals key molecules in metastatic potentials and organ-tropisms of hepatocellular carcinoma

Metastasis is a landmark event for rapid postsurgical relapse and death of HCC patients. Although distinct genomic and transcriptomic profiling of HCC metastasis had been reported previously, the causal relationships of somatic mutants, mRNA levels and metastatic potentials were difficult to be established in clinic. Therefore, 11 human HCC cell lines and 7 monoclonal derivatives with definite metastatic potentials and tropisms were subjected to whole exome sequencing (WES) and whole transcriptome sequencing (WTS). TP53, MYO5A, ROS1 and ARID2 were the prominent mutants of metastatic drivers in HCC cells. During HCC clonal evaluation, TP53, MYO5A and ROS1 mutations occurred in the early stage, EXT2 and NIN in the late stage. NF1 mutant was unique in lung tropistic cell lines, RNF126 mutant in lymphatic tropistic ones. PER1, LMO2, GAS7, NR4A3 expression levels were positively associated with relapse-free survival (RFS) of HCC patients. The integrative analysis revealed 58 genes exhibited both somatic mutation and dysregulated mRNA levels in high metastatic cells. Altogether, metastatic drivers could accumulate gradually at different stages during HCC progression, some drivers might modulate HCC metastatic potentials and the others regulate metastatic tropisms.

Ezrin and Its Phosphorylated Thr567 Form Are Key Regulators of Human Extravillous Trophoblast Motility and Invasion

The protein ezrin has been shown to enhance cancer cell motility and invasion leading to malignant behaviours in solid tumours, but a similar regulatory function in the early physiological reproduction state is, however, much less clear. We speculated that ezrin may play a key role in promoting first-trimester extravillous trophoblast (EVT) migration/invasion. Ezrin, as well as its Thr567 phosphorylation, were found in all trophoblasts studied, whether primary cells or lines. Interestingly, the proteins were seen in a distinct cellular localisation in long, extended protrusions in specific regions of cells. Loss-of-function experiments were carried out in EVT HTR8/SVneo and Swan71, as well as primary cells, using either ezrin siRNAs or the phosphorylation Thr567 inhibitor NSC668394, resulting in significant reductions in both cell motility and cellular invasion, albeit with differences between the cells used. Our analysis further demonstrated that an increase in focal adhesion was, in part, able to explain some of the molecular mechanisms involved. Data collected using human placental sections and protein lysates further showed that ezrin expression was significantly higher during the early stage of placentation and, importantly, clearly seen in the EVT anchoring columns, further supporting the potential role of ezrin in regulating migration and invasion in vivo.

Persistent Escherichia coli infection in renal tubular cells enhances calcium oxalate crystal-cell adhesion by inducing ezrin translocation to apical membranes via Rho/ROCK pathway

Recent evidence has suggested that recurrent urinary tract infection (UTI) can cause not only infection stones but also metabolic stones (e.g., those containing calcium oxalate monohydrate or COM). However, precise mechanisms underlying UTI-induced metabolic stones remained unknown. In this study, Escherichia coli, the most common bacterium found in recurrent UTI was used to establish the in vitro model for persistent infection of renal epithelial cells. The promoting effects of persistent E. coli infection on kidney stone formation were validated by COM crystal-cell adhesion assay, followed by immunofluorescence study for changes in surface expression of the known COM crystal receptors. Among the five receptors examined, only ezrin had significantly increased level on the surface of persistently infected cells without change in its total level. Such translocation of ezrin to apical membranes was confirmed by Western blotting of apical membrane and cytosolic fractions and confocal microscopic examination. Additionally, persistent infection increased phosphorylation (Thr567) of ezrin. However, all of these changes induced by persistent E. coli infection were significantly inhibited by small-interfering RNA (siRNA) specific for ezrin or a Rho-associated kinase (ROCK)-specific inhibitor (Y-27632). In summary, this study provides a piece of evidence demonstrating that persistent infection by E. coli, one of the non-urease-producing bacteria, may contribute to COM metabolic stone formation by translocation of ezrin to apical membranes, thereby promoting COM crystal-cell adhesion. Such ezrin translocation was mediated via Rho/ROCK signaling pathway. These findings may, at least in part, explain the pathogenic mechanisms underlying recurrent UTI-induced metabolic kidney stone disease.

Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target

Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.

Mechanosensitive turnover of phosphoribosyl pyrophosphate synthetases regulates nucleotide metabolism

Cells coordinate their behaviors with the mechanical properties of the extracellular matrix (ECM). Tumor cells frequently harbor an enhanced nucleotide synthesis, presumably to meet the increased demands for rapid proliferation. Nevertheless, how ECM rigidity regulates nucleotide metabolism remains elusive. Here we show that shift from stiff to soft matrix blunts glycolysis-derived nucleotide synthesis in tumor cells. Soft ECM results in TNF receptor-associated factor 2 (TRAF2)-dependent K29 ubiquitination and degradation of phosphoribosyl pyrophosphate synthetase (PRPS)1/2. Recruitment of TRAF2 to PRPS1/2 requires phosphorylation of PRPS1 S285 or PRPS2 T285, which is mediated by low stiffness-activated large tumor suppressor (LATS)1/2 kinases. Further, non-phosphoryable or non-ubiquitinatable PRPS1/2 mutations maintain PRPS1/2 expression and nucleotide synthesis at low stiffness, and promote tumor growth and metastasis. Our findings demonstrate that PRPS1/2 stability and nucleotide metabolism is ECM rigidity-sensitive, and thereby highlight a regulatory cascade underlying mechanics-guided tumor metabolism reprogramming.

Rho-Kinase as a Target for Cancer Therapy and Its Immunotherapeutic Potential

Cancer immunotherapy is fast rising as a prominent new pillar of cancer treatment, harnessing the immune system to fight against numerous types of cancer. Rho-kinase (ROCK) pathway is involved in diverse cellular activities, and is therefore the target of interest in various diseases at the cellular level including cancer. Indeed, ROCK is well-known for its involvement in the tumor cell and tumor microenvironment, especially in its ability to enhance tumor cell progression, migration, metastasis, and extracellular matrix remodeling. Importantly, ROCK is also considered to be a novel and effective modulator of immune cells, although further studies are needed. In this review article, we describe the various activities of ROCK and its potential to be utilized in cancer treatment, particularly in cancer immunotherapy, by shining a light on its activities in the immune system.

Acetylation of ezrin regulates membrane-cytoskeleton interaction underlying CCL18-elicited cell migration

Ezrin, a membrane–cytoskeleton linker protein, plays an essential role in cell polarity establishment, cell migration, and division. Recent studies show that ezrin phosphorylation regulates breast cancer metastasis by promoting cancer cell survivor and promotes intrahepatic metastasis via cell migration. However, it was less characterized whether there are additional post-translational modifications and/or post-translational crosstalks on ezrin underlying context-dependent breast cancer cell migration and invasion. Here we show that ezrin is acetylated by p300/CBP-associated factor (PCAF) in breast cancer cells in response to CCL18 stimulation. Ezrin physically interacts with PCAF and is a cognate substrate of PCAF. The acetylation site of ezrin was mapped by mass spectrometric analyses, and dynamic acetylation of ezrin is essential for CCL18-induced breast cancer cell migration and invasion. Mechanistically, the acetylation reduced the lipid-binding activity of ezrin to ensure a robust and dynamic cycling between the plasma membrane and cytosol in response to CCL18 stimulation. Biochemical analyses show that ezrin acetylation prevents the phosphorylation of Thr567. Using atomic force microscopic measurements, our study revealed that acetylation of ezrin induced its unfolding into a dominant structure, which prevents ezrin phosphorylation at Thr567. Thus, these results present a previously undefined mechanism by which CCL18-elicited crosstalks between the acetylation and phosphorylation on ezrin control breast cancer cell migration and invasion. This suggests that targeting PCAF signaling could be a potential therapeutic strategy for combating hyperactive ezrin-driven cancer progression.

Ezrin Mediates Invasion and Metastasis in Tumorigenesis: A Review

Ezrin, as encoded by the EZR gene, is a member of the Ezrin/Radixin/Moesin (ERM) family. The ERM family includes three highly related actin filament binding proteins, Ezrin, Radixin, and Moesin. These three members share similar structural properties containing an N-terminal domain named FERM, a central helical linker region, and a C-terminal domain that mediates the interaction with F-actin. Ezrin protein is highly regulated through the conformational change between a closed, inactivate form and an open, active form. As a membrane-cytoskeleton linker protein, Ezrin facilitates numerous signal transductions in tumorigenesis and mediates diverse essential functions through interactions with a variety of growth factor receptors and adhesion molecules. Emerging evidence has demonstrated that Ezrin is an oncogene protein, as high levels of Ezrin are associated with metastatic behavior in various types of cancer. The diverse functions attributed to Ezrin and the understanding of how Ezrin drives the deadly process of metastasis are complex and often controversial. Here by reviewing recent findings across a wide spectrum of cancer types we will highlight the structures, protein interactions and oncogenic roles of Ezrin as well as the emerging therapeutic agents targeting Ezrin. This review provides a comprehensive framework to guide future studies of Ezrin and other ERM proteins in basic and clinical studies.

Hypoxia-induced autophagy drives colorectal cancer initiation and progression by activating the PRKC/PKC-EZR (ezrin) pathway

In solid tumors, cancer stem cells (CSCs) or tumor-initiating cells (TICs) are often found in hypoxic niches. Nevertheless, the influence of hypoxia on TICs is poorly understood. Using previously established, TIC-enrichedpatient-derived colorectal cancer (CRC) cultures, we show that hypoxia increases the self-renewal capacity of TICs while inducing proliferation arrest in their more differentiated counterpart cultures. Gene expression data revealed macroautophagy/autophagy as one of the major pathways induced by hypoxia in TICs. Interestingly, hypoxia-induced autophagy was found to induce phosphorylation of EZR (ezrin) at Thr567 residue, which could be reversed by knocking down ATG5, BNIP3, BNIP3L, or BECN1. Furthermore, we identified PRKCA/PKCα as a potential kinase involved in hypoxia-induced autophagy-mediated TIC self-renewal. Genetic targeting of autophagy or pharmacological inhibition of PRKC/PKC and EZR resulted in decreased tumor-initiating potential of TICs. In addition, we observed significantly reduced in vivo tumor initiation and growth after a stable knockdown of ATG5. Analysis of human CRC samples showed that p-EZR is often present in TICs located in the hypoxic and autophagic regions of the tumor. Altogether, our results establish the hypoxia-autophagy-PKC-EZR signaling axis as a novel regulatory mechanism of TIC self-renewal and CRC progression. Autophagy inhibition might thus represent a promising therapeutic strategy for cancer patients.

ABBREVIATIONS

ATG: autophagy related; BECN1: beclin 1; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; CQ: chloroquine; CSC: cancer stem cells; CRC: colorectal cancer; HIF1A/HIF-1α: hypoxia inducible factor 1 subunit alpha; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PRKC/PKC: protein kinase C; SQSTM1/p62: sequestosome 1; TICs: tumor-initiating cells.

Celastrol inhibits ezrin-mediated migration of hepatocellular carcinoma cells

Progression of hepatocellular carcinoma involves multiple genetic and epigenetic alterations that promote cancer invasion and metastasis. Our recent study revealed that hyperphosphorylation of ezrin promotes intrahepatic metastasis in vivo and cell migration in vitro. Celastrol is a natural product from traditional Chinese medicine which has been used in treating liver cancer. However, the mechanism of action underlying celastrol treatment was less clear. Here we show that ROCK2 is a novel target of celastrol and inhibition of ROCK2 suppresses elicited ezrin activation and liver cancer cell migration. Using cell monolayer wound healing, we carried out a phenotype-based screen of natural products and discovered the efficacy of celastrol in inhibiting cell migration. The molecular target of celastrol was identified as ROCK2 using celastrol affinity pull-down assay. Our molecular docking analyses indicated celastrol binds to the active site of ROCK2 kinase. Mechanistically, celastrol inhibits the ROCK2-mediated phosphorylation of ezrin at Thr567 which harnesses liver cancer cell migration. Our findings suggest that targeting ROCK2-ezrin signaling is a potential therapeutic niche for celastrol-based intervention of cancer progression in hepatocellular carcinoma.

Immunohistochemical Study of Ezrin Expression in Colorectal Carcinoma: A Comparative Study between Objective Method and Digital Quantitative Assessment

BACKGROUND

Colorectal cancer is one of the leading causes of cancer death in both developed and developing nations. It is the third most common type of cancer and the fourth leading cause of cancer-related deaths worldwide. Ezrin is involved in maintaining cell structure and cell motility. Expression levels of the ezrin gene correlate with numerous human malignancies.

MATERIAL AND METHODS

Ezrin expression was evaluated in fifty one cases of colorectal carcinoma by using two methods; objective and quantitative method to determine the statistical relation between ezrin objective analysis score and clinicopathological parameters and to do a comparative study between both methods of analysis.

RESULTS

Ezrin was expressed in 92.2% of cases, and it showed a statistical significant relation with tumor grade. A statistically significant relation was found between ezrin objective analysis score and ezrin quantitative analysis score (P-value <0.05). A strong positive Pearson correlation exists between both methods of analysis (R=0.868).

CONCLUSION

Ezrin has a role in colorectal cancer progression and it might provide clinically valuable information in predicting the behavior of colorectal cancer. Digital pathology offers the potential for improvements in quality, efficacy and safety. It will be necessary to carry out similar studies on a larger sample size in order to elucidate the possible prognostic significance of ezrin in colorectal carcinoma and ensure the ability of digital pathology to transform the practice of diagnostic pathology. 
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Circ-TCF4.85 silencing inhibits cancer progression through microRNA-486-5p-targeted inhibition of ABCF2 in hepatocellular carcinoma

The current study aimed to explore the role of the circular RNA circ‐TCF4.85 and its downstream target microRNA‐486‐5p (miR‐486‐5p) in hepatocellular carcinoma (HCC) development. Circ‐TCF4.85 was detected to be highly expressed in HCC tissues. Next, we found that silencing of circ‐TCF4.85 repressed HCC cell proliferation, invasion, and migration, while enhancing apoptosis. In addition, biotin‐coupled probe pull‐down and miRNA capture assays, as well as fluorescence in situ hybridization, confirmed that circ‐TCF4.85 could bind to miR‐486‐5p. In rescue experiments, miR‐486‐5p had the potential to eliminate the tumor‐suppressive effects of circ‐TCF4.85 knockdown in HCC. Moreover, miR‐486‐5p was shown to target ABCF2 gene, which was positively regulated by circ‐TCF4.85. Finally, nude mice subcutaneously injected with si‐circ‐TCF4.85‐transfected HCC cells presented with inhibited xenograft tumor formation in vivo. Taken together, our results reveal that silencing of circ‐TCF4.85 suppresses HCC progression via miR‐486‐5p‐targeted inhibition of ABCF2.

Ezrin Phosphorylation at T567 Modulates Cell Migration, Mechanical Properties, and Cytoskeletal Organization

Ezrin, a member of the ERM (ezrin/radixin/moesin) family of proteins, serves as a crosslinker between the plasma membrane and the actin cytoskeleton. By doing so, it provides structural links to strengthen the connection between the cell cortex and the plasma membrane, acting also as a signal transducer in multiple pathways during migration, proliferation, and endocytosis. In this study, we investigated the role of ezrin phosphorylation and its intracellular localization on cell motility, cytoskeleton organization, and cell stiffness, using fluorescence live-cell imaging, image quantification, and atomic force microscopy (AFM). Our results show that cells expressing constitutively active ezrin T567D (phosphomimetic) migrate faster and in a more directional manner, especially when ezrin accumulates at the cell rear. Similarly, image quantification results reveal that transfection with ezrin T567D alters the cell’s gross morphology and decreases cortical stiffness. In contrast, constitutively inactive ezrin T567A accumulates around the nucleus, and although it does not impair cell migration, it leads to a significant buildup of actin fibers, a decrease in nuclear volume, and an increase in cytoskeletal stiffness. Finally, cell transfection with the dominant negative ezrin FERM domain induces significant morphological and nuclear changes and affects actin, microtubules, and the intermediate filament vimentin, resulting in cytoskeletal fibers that are longer, thicker, and more aligned. Collectively, our results suggest that ezrin’s phosphorylation state and its intracellular localization plays a pivotal role in cell migration, modulating also biophysical properties, such as membrane–cortex linkage, cytoskeletal and nuclear organization, and the mechanical properties of cells.

LOXL2 Upregulates Phosphorylation of Ezrin to Promote Cytoskeletal Reorganization and Tumor Cell Invasion

Lysyl oxidase-like 2 (LOXL2), a copper-dependent enzyme of the lysyl oxidase family and its nonsecreted, catalytically dead spliced isoform L2Δ13, enhance cell migration and invasion, stimulate filopodia formation, modulate the expression of cytoskeletal genes, and promote tumor development and metastasis in vivo. We previously showed that LOXL2 reorganizes the actin cytoskeleton in esophageal squamous cell carcinoma (ESCC) cells, however, the underlying molecular mechanisms were not identified. Here, using interactome analysis, we identified ezrin (EZR), fascin (FSCN1), heat shock protein beta-1 (HSPB1), and tropomodulin-3 (TMOD3) as actin-binding proteins that associate with cytoplasmic LOXL2, as well as with its L2Δ13 variant. High levels of LOXL2 and L2Δ13 and their cytoskeletal partners correlated with poor clinical outcome in patients with ESCC. To better understand the significance of these interactions, we focused on the interaction of LOXL2 with ezrin. Phosphorylation of ezrin at T567 was greatly reduced following depletion of LOXL2 and was enhanced following LOXL2/L2Δ13 reexpression. Furthermore, LOXL2 depletion inhibited the ability of ezrin to promote tumor progression. These results suggest that LOXL2-induced ezrin phosphorylation, which also requires PKCα, is critical for LOXL2-induced cytoskeletal reorganization that subsequently promotes tumor cell invasion and metastasis in ESCC. In summary, we have characterized a novel molecular mechanism that mediates, in part, the protumorigenic activity of LOXL2. These findings may enable the future development of therapeutic agents targeting cytoplasmic LOXL2. SIGNIFICANCE: LOXL2 and its spliced isoform L2Δ13 promote cytoskeletal reorganization and invasion of esophageal cancer cells by interacting with cytoplasmic actin-binding proteins such as ezrin.

Inhibition of Ezrin suppresses cell migration and invasion in human nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most severe types of malignant cancer of the head and neck as it is difficult to treat. Ezrin is highly expressed in numerous types of cancer. However, the role of Ezrin in NPC has not been fully investigated and further studies are required in order to uncover its therapeutic potential in the treatment of NPC. The aim of the present study was to investigate the expression of Ezrin in human NPC and to evaluate the effect of knockdown of Ezrin using small interfering (si)-RNA on NPC cell migration and invasion. The expression levels of Ezrin were determined using reverse transcription-quantitative polymerase chain reaction, immunohistochemical staining and western blotting. Following transfection of Ezrin-siRNA into NPC cells, cell invasion and migration were analyzed and the mRNA expression levels of matrix metalloproteinase(MMP)-2 and MMP9 were determined. The results revealed that the expression of Ezrin was markedly increased in human NPC tissue samples compared with normal adjacent nasopharyngeal tissue samples. Ezrin was also highly expressed in the NPC cell lines 6-10B and C6661 when compared with the normal nasopharyngeal cell line NP69. Transfection of NPC cell lines with siRNA targeting Ezrin significantly inhibited NPC cell migration and invasion, and downregulated the mRNA expression level of MMP2; however, no effect was observed on MMP9 mRNA expression. At the same time, knockdown of Ezrin significantly decreased the expression levels of phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt), which downregulated the mRNA expression of MMP2. In conclusion, the results revealed that knockdown of Ezrin suppressed NPC migration and invasion by reducing the mRNA expression of MMP2 via the PI3K/Akt signaling pathway. These results highlight the important role of Ezrin in NPC cell migration and invasion. In addition, they indicate that silencing of Ezrin may serve as a potential therapeutic strategy to treat human NPC.

Ezrin promotes breast cancer progression by modulating AKT signals

Background

Ezrin, which is known as a cytoskeleton linker protein, is closely linked with the metastatic progression of cancer and is frequently abnormally expressed in aggressive cancer types. However, the possible involvement of Ezrin in metastasis and angiogenesis in breast cancer remains unclear.

Methods

Immunohistochemical analysis of Ezrin was performed on both BC samples (n = 117) and normal epithelium samples (n = 47). In vivo and in vitro assays were performed to validate the effect of Ezrin on AKT pathway-mediated BC progression.

Results

In this study, Ezrin was found to be upregulated in BC tissues, which was linked with aggressive tumour characteristics and poor prognosis. Moreover, we showed that Ezrin promotes BC proliferation, migration, invasion, and angiogenesis in vitro and in vivo. Mechanistic analysis showed that Ezrin interacted with AKT, and promoted its kinase activity, thereby regulating the AKT pathway in BC.

Conclusions

In all, we propose a model for an Ezrin/AKT oncoprotein axis, which provides novel insight into how Ezrin contributes to BC progression.

Coordinated Regulation of Intracellular Fascin Distribution Governs Tumor Microvesicle Release and Invasive Cell Capacity

Tumor cell invasion is one result of the bidirectional interactions occurring between tumor cells and the surrounding milieu. The ability of tumor cells to invade through the extracellular matrix is in part regulated by the formation of a class of protease-loaded extracellular vesicles, called tumor microvesicles (TMVs), which are released directly from the cell surface. Here we show that the actin bundling protein, fascin, redistributes to the cell periphery in a ternary complex with podocalyxin and ezrin, where it promotes TMV release. The peripheral localization of fascin is prompted by the loss of Rab35 signaling, which in turn unleashes ARF6 activation. The result is a mechanism through which Rab35 and ARF6 cooperatively and simultaneously regulate the distribution and localization of fascin and promote oncogenic signaling, which leads to TMV release while inhibiting invadopodium formation. These studies are clinically significant as fascin-loaded TMVs can be detected in bodily fluids and elevated fascin expression coupled with low Rab35 levels correlates with poor overall survival in some cancers.

The transmembrane adaptor protein NTAL limits mast cell chemotaxis toward prostaglandin E2

Chemotaxis of mast cells is one of the crucial steps in their development and function. Non–T cell activation linker (NTAL) is a transmembrane adaptor protein that inhibits the activation of mast cells and B cells in a phosphorylation-dependent manner. Here, we studied the role of NTAL in the migration of mouse mast cells stimulated by prostaglandin E2 (PGE2). Although PGE2 does not induce the tyrosine phosphorylation of NTAL, unlike IgE immune complex antigens, we found that loss of NTAL increased the chemotaxis of mast cells toward PGE2. Stimulation of mast cells that lacked NTAL with PGE2 enhanced the phosphorylation of AKT and the production of phosphatidylinositol 3,4,5-trisphosphate. In resting NTAL-deficient mast cells, phosphorylation of an inhibitory threonine in ERM family proteins accompanied increased activation of β1-containing integrins, which are features often associated with increased invasiveness in tumors. Rescue experiments indicated that only full-length, wild-type NTAL restored the chemotaxis of NTAL-deficient cells toward PGE2. Together, these data suggest that NTAL is a key inhibitor of mast cell chemotaxis toward PGE2, which may act through the RHOA/ERM/β1-integrin and PI3K/AKT axes.

The -250G/A and -514C/T Polymorphisms in Hepatic Lipase Gene Promoter Confers an Increased Risk of Hepatocellular Carcinoma in a Chinese Population

INTRODUCTION AND AIM

Hepatocellular carcinoma (HCC) is a lethal malignancy, but the molecular mechanisms of hepatocarcinogenesis remain undefined. The present study aims to investigate the relationship between polymorphisms of the hepatic lipase (HL) gene promoters and risk of HCC.

MATERIAL AND METHODS

Totally, 279 HCC patients and 200 healthy individuals were enrolled. Polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) was used to analyze the genotypes of HL gene. Logistic regression analysis was conducted to identify risk factors of HCC.

RESULTS

There was significant difference in the distribution of smoking history, drinking history, and family history of subjects between the case and control groups (all p < 0.05). Difference in the -250G/A (p = 0.011; OR = 1.61; 95%CI: 1.11-2.34) and -514C/T (p = 0.007; OR = 1.65; 95%CI: 1.14-2.38) genotypes and allele frequencies between two groups was significant. A higher risk of HCC was identified in those with polymorphisms in the - 250G/A (p = 0.007; OR = 1.45; 95%CI: 1.11-1.89) and -514C/T (p = 0.003; OR = 1.51; 95%CI: 1.15-2.00). Polymorphisms at - 250G/A (GA + AA) (p = 0.025; OR = 1.55; 95%CI: 1.06-2.28), -514C/T (CT + TT) (p = 0.021; OR = 1.57; 95%CI: 1.07-2.29), smoking history (p = 0.017; OR = 1.70; 95%CI: 1.10-2.63) and drinking history (p = 0.003; OR = 2.04; 95%CI: 1.27-3.27) were significantly related to the risk of HCC (all p < 0.05).

CONCLUSION

The results obtained from this study indicated that polymorphisms of -250G/A and -514C/T in HL gene promoters were associated with the risk of HCC.

S100P and Ezrin promote trans-endothelial migration of triple negative breast cancer cells

PURPOSE

Triple negative breast cancer (TNBC) patients generally have an adverse clinical outcome because their tumors often recur and metastasize to distant sites in the first 3 years after surgery. Therefore, it has become pivotal to identify potential factors associated with metastasis. Here, we focused on the effects of S100P and Ezrin on the trans-endothelial migration (TEM) of TNBC cells, as they have both been suggested to play a role in this process in other malignancies.

METHODS

The expression of S100P and Ezrin was examined by immunohistochemistry in 58 primary TNBC samples. The mRNA and protein levels of S100P and Ezrin were assessed in breast cancer-derived cell lines using qRT-PCR and Western blotting, respectively. Proliferation and migration assays were performed using TNBC-derived MFM-223 and SUM-185-PE cells transfected with S100P and Ezrin siRNAs. Two different timeframes were employed for TEM assays using TNBC-derived cells and human umbilical vein endothelial-derived cells, respectively. Correlations between the status of Ezrin^Thr-567 expression and various clinicopathological features were analyzed by immunohistochemistry.

RESULTS

We found that S100P and Ezrin double negative TNBC cases were significantly associated with a better disease-free survival. We also found that single and double siRNA-mediated knockdown of S100P and Ezrin in TNBC-derived cells significantly inhibited their TEM and destabilized the intercellular junctions of endothelial cells. In addition, we found that Ezrin^Thr-567 immunoreactivity significantly correlated with vascular invasion in TNBC patients.

CONCLUSIONS

From our data we conclude that S100P, Ezrin and Ezrin^Thr-567 are involved in the trans-endothelial migration of TNBC cells and that they may serve as potential targets in TNBC patients.

TGFβ and IGF1R signaling activates protein kinase A through differential regulation of ezrin phosphorylation in colon cancer cells

Aberrant cell survival plays a critical role in cancer progression and metastasis. We have previously shown that ezrin, a cAMP-dependent protein kinase A-anchoring protein (AKAP), is up-regulated in colorectal cancer (CRC) liver metastasis. Phosphorylation of ezrin at Thr-567 activates ezrin and plays an important role in CRC cell survival associated with XIAP and survivin up-regulation. In this study, we demonstrate that in FET and GEO colon cancer cells, knockdown of ezrin expression or inhibition of ezrin phosphorylation at Thr-567 increases apoptosis through protein kinase A (PKA) activation in a cAMP-independent manner. Transforming growth factor (TGF) β signaling inhibits ezrin phosphorylation in a Smad3-dependent and Smad2-independent manner and regulates pro-apoptotic function through ezrin-mediated PKA activation. On the other hand, ezrin phosphorylation at Thr-567 by insulin-like growth factor 1 receptor (IGF1R) signaling leads to cAMP-dependent PKA activation and enhances cell survival. Further studies indicate that phosphorylated ezrin forms a complex with PKA RII, and dephosphorylated ezrin dissociates from the complex and facilitates the association of PKA RII with AKAP149, both of which activate PKA yet lead to either cell survival or apoptosis. Thus, our studies reveal a novel mechanism of differential PKA activation mediated by TGFβ and IGF1R signaling through regulation of ezrin phosphorylation in CRC, resulting in different cell fates. This is of significance because TGFβ and IGF1R signaling pathways are well-characterized tumor suppressor and oncogenic pathways, respectively, with important roles in CRC tumorigenesis and metastasis. Our studies indicate that they cross-talk and antagonize each other's function through regulation of ezrin activation. Therefore, ezrin may be a potential therapeutic target in CRC.

MicroRNA-1291 targets the FOXA2-AGR2 pathway to suppress pancreatic cancer cell proliferation and tumorigenesis

Pancreatic cancer is the fourth leading cause of cancer death in the United States. Better understanding of pancreatic cancer biology may help identify new oncotargets towards more effective therapies. This study investigated the mechanistic actions of microRNA-1291 (miR-1291) in the suppression of pancreatic tumorigenesis. Our data showed that miR-1291 was downregulated in a set of clinical pancreatic carcinoma specimens and human pancreatic cancer cell lines. Restoration of miR-1291 expression inhibited pancreatic cancer cell proliferation, which was associated with cell cycle arrest and enhanced apoptosis. Furthermore, miR-1291 sharply suppressed the tumorigenicity of PANC-1 cells in mouse models. A proteomic profiling study revealed 32 proteins altered over 2-fold in miR-1291-expressing PANC-1 cells that could be assembled into multiple critical pathways for cancer. Among them anterior gradient 2 (AGR2) was reduced to the greatest degree. Through computational and experimental studies we further identified that forkhead box protein A2 (FOXA2), a transcription factor governing AGR2 expression, was a direct target of miR-1291. These results connect miR-1291 to the FOXA2-AGR2 regulatory pathway in the suppression of pancreatic cancer cell proliferation and tumorigenesis, providing new insight into the development of miRNA-based therapy to combat pancreatic cancer.

Rho/ROCK Pathway Regulates Migration and Invasion of Esophageal Squamous Cell Carcinoma by Regulating Caveolin-1

BACKGROUND Esophageal squamous cell carcinoma (ESCC) is a common cancer with poor prognosis. Caveolin-1 (Cav1) and Rho/ROCK pathway play important roles in tumor metastasis, separately. However, less research was focused on the relationship between Cav1 and Rho/ROCK in ECSS metastasis. Therefore, we investigated the relationship between Cav1 and Rho/ROCK pathway in ESCC metastasis. MATERIAL AND METHODS Cav1 and phosphorylated Cav1 (PY14Cav1) were examined in ESCC and in adjacent and non-tumorous tissues from ESCC patients by immunohistochemistry (IHC). Small interfering RNA (siRNA) targeting Cav1 or Rho/ROCK inhibitor was used to treat EC109, Eca109, TE1, and TE13 cells. Western blotting (WB) was used to detect Cav1 and PY14Cav1 expression. The wound healing scratch test and transwell assays were used to assess migration and invasion. RESULTS Cav1 and PY14Cav1 were gradually expressed at higher levels in ECSS than in adjacent and non-tumor tissues as ESCC stage and lymphatic metastasis increased, and this difference was significant (P<0.05). Cav1 was expressed at higher levels in TE1 and TE13 than in EC109 and Eca109, while PY14Cav1 was enhanced in TE1 and TE13 cells but not in EC109 and Eca109, and the difference was significant (P<0.05). TE1 and TE13 had significantly (P<0.05) stronger motility, migratory, and invasion abilities than EC109 and Eca109 cells. Silencing Cav1 decreased PY14Cav1 expression in TE1 and TE13 cells, as well as suppressing the migration and invasion of all ECSS cells, and these differences were significant (P<0.05). Suppressing the Rho/ROCK pathway obviously inhibited Cav1 and PY14Cav1 expressions, as well as significantly (P<0.05) decreasing migration and invasion of ESCC cells. CONCLUSIONS Cav1 and PY14Cav1 were positively correlated with ESCC lymphatic metastasis and cancer stages. Rho/ROCK pathway activation promoted ESCC metastasis by regulating Cav1.

Effects of arsenic trioxide on the expression of ezrin in hepatocellular carcinoma

The aim of the study was to investigate the effects of arsenic trioxide (As2O3) treatment on the expression of ezrin and serum alpha-fetoprotein (AFP) levels in hepatocellular carcinoma (HCC).A total of 24 patients (20 males and 4 females) with resectable HCC were treated with venous injection of As2O3 for 14 days (10 mg/d) before surgery. The ezrin expression and serum AFP levels were assessed before and after treatment, respectively.The serum AFP levels were 325.5 ng/L before treatment and 278.6 ng/L after treatment, with statistical significant difference (Z = -2.360, P < .05). The expression of ezrin was negative, weak positive, and strong positive in 11, 7, and 6 cases, respectively, before As2O3 treatment, and 17, 5, 2 cases respectively after the treatment. The difference between the 2 groups was statistically significant (χ = 5.619, P < .05). Also, the results showed that there was a significant correlation between the high serum AFP level (AFP ≥ 500 ng/L) and high expression of ezrin (χ = 8.080, P < .05).As2O3 treatment can significantly downregulate the expression of ezrin in HCC.

NHE1 has a notable role in metastasis and drug resistance of T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) represents a spectrum of hematological malignancies that affect human health. Metastasis and chemotherapeutic drug resistance are the primary causes of mortality in patients with T-ALL. Sodium-hydrogen antiporter 1 (NHE1) is established to serve a role in metastasis and drug resistance in numerous types of cancer; however, the function of NHE1 in T-ALL remains to be elucidated. Previously, the C-C-motif chemokine ligand 25 (CCL25) was identified to be involved in metastasis and drug resistance in the MOLT4 T-ALL cell line, as was the ezrin protein. The present study investigated the role of NHE1 in the metastasis of T-ALL using a Transwell assay and scanning electron microscopy, using MOLT4 cells as a model. The association between NHE1 and ezrin was assessed using laser scanning confocal microscopy. The effect of NHE1 on resistance to the chemotherapy drug doxorubicin (DOX) was also investigated using a cell viability and cytotoxicity assay. Expression of NHE1 increased following treatment with CCL25, accompanied by morphological changes in MOLT4 cells and the co-localization of NHE1 with ezrin. In addition, wild-type MOLT4 cells exhibited an increased polarization ability compared with NHE1- or ezrin-silenced cells. NHE1- or ezrin-silenced cells exhibited higher sensitivity to DOX compared with wild-type MOLT4 cells. In conclusion, the increased expression or activity of NHE1 may potentially be a poor prognostic indicator for human T-ALL.

MicroRNA-374a Promotes Hepatocellular Carcinoma Cell Proliferation by Targeting Mitogen-Inducible Gene 6 (MIG-6)

Hepatocellular carcinoma (HCC) is a disease with poor prognosis rates and ineffective therapeutic options. Previous studies have reported the involvement of mitogen-inducible gene 6 (MIG-6) as a negative regulator in tumor formation. MicroRNAs (miRNAs) play crucial roles in the development of different types of cancer. However, the underlying mechanisms of miRNAs in HCC are poorly understood. This study was aimed to investigate the role of miR-374a in HCC and its role in the regulation of expression of MIG-6. The results showed that MIG-6 overexpression significantly inhibited cell viability of HepG2 cells after 4 days posttransfection. Moreover, MIG-6 was a direct target of miR-374a, and the expression of MIG-6 was remarkably downregulated by the overexpression of miR-374a in HepG2 cells. Furthermore, we found that overexpression of miR-374a promoted cell viability; however, the protective effect was abolished by MIG-6 overexpression. In addition, overexpression of miR-374a activated the EGFR and AKT/ERK signaling pathways by regulation of MIG-6. Our findings suggest that miR-374a could promote cell viability by targeting MIG-6 and activating the EGFR and AKT/ERK signaling pathways. These data provide a promising therapeutic strategy for HCC treatment.

Ezrin Ser66 phosphorylation regulates invasion and metastasis of esophageal squamous cell carcinoma cells by mediating filopodia formation

BACKGROUND

Ezrin, links the plasma membrane to the actin cytoskeleton, and plays an important role in the development and progression of human esophageal squamous cell carcinoma (ESCC). However, the roles of ezrin S66 phosphorylation in tumorigenesis of ESCC remain unclear.

METHODS

Distribution of ezrin in membrane and cytosol fractions was examined by analysis of detergent-soluble/-insoluble fractions and cytosol/membrane fractionation. Both immunofluorescence and live imaging were used to explore the role of ezrin S66 phosphorylation in the behavior of ezrin and actin in cell filopodia. Cell proliferation, migration and invasion of ESCC cells were investigated by proliferation and migration assays, respectively. Tumorigenesis, local invasion and metastasis were assessed in a nude mouse model of regional lymph node metastasis.

RESULTS

Ezrin S66 phosphorylation enhanced the recruitment of ezrin to the membrane in ESCC cells. Additionally, non-phosphorylatable ezrin (S66A) significantly prevented filopodia formation, as well as caused a reduction in the number, length and lifetime of filopodia. Moreover, functional experiments revealed that expression of non-phosphorylatable ezrin (S66A) markedly suppressed migration and invasion but not proliferation of ESCC cells in vitro, and attenuated local invasion and regional lymph node metastasis, but not primary tumor growth of ESCC cells in vivo.

CONCLUSION

Ezrin S66 phosphorylation enhances filopodia formation, contributing to the regulation of invasion and metastasis of esophageal squamous cell carcinoma cells.

Downregulation of SRC Kinase Signaling Inhibitor 1 (SRCIN1) Expression by MicroRNA-32 Promotes Proliferation and Epithelial-Mesenchymal Transition in Human Liver Cancer Cells

MicroRNAs play an important role in regulating gene expression by binding to the 3′-UTR of target mRNAs. In this study, we have made an attempt to assess the molecular mechanisms by which miR-32 suppresses the expression of SRCIN1, thereby leading to promotion of proliferation and epithelial–mesenchymal transition of human liver cancer cells. Human liver cancer cell line HepG2 was transfected with miR-32 mimics and its control. The HepG2 cells were assessed for miR-32 expression. The transfected cells were then studied for SRCIN1 expression by luciferase assay, effect of transfection on cell proliferation, and epithelial–mesenchymal transition. SRCIN1 expression was downregulated in the human liver cancer cell line HepG2. Overexpression of SRCIN1 inhibited the proliferation of human liver HepG2 cancer cells and blocked epithelial–mesenchymal transition. It was observed that SRCIN1 expression was regulated by miR-32 in human liver cancer cells. Overexpression of miR-32 promoted cell proliferation and epithelial–mesenchymal transition of human liver cancer HepG2 cells. Our data demonstrated that SRCIN1 functions as a tumor suppressor in human liver cancers. Additionally, SRCIN1 functions to inhibit the proliferation and epithelial–mesenchymal transition of human liver cancer HepG2 cells. miRNA-32 was a direct target of SRCIN1. Overexpression of miR-32 promoted cell proliferation and epithelial–mesenchymal transition of human liver cancer HepG2 cells.

Ezrin/NF-kB activation regulates epithelial- mesenchymal transition induced by EGF and promotes metastasis of colorectal cancer

There is growing evidence that epithelial mesenchymal-transition (EMT) plays significant roles in terms of tumor metastasis. There are a lot of cytokines inducing EMT of tumor cells, EGF is one of the important cytokines.Ezrin is a connexin between the cytoskeleton and the cell membrane, which is closely related to the morphological movement and metastasis of tumor cells.EGF can activate Ezrin and affects cell motility. In recent years, many studies have shown that NF-kB acts as an important transcription factor, involving in the process of EMT. However, does Ezrin participate in the regulation of EGF-induced EMT through the NF-kB pathway? This question needs us to discuss.In the present study, we found that EGF could induce colorectal cancer cells to develop EMT,enhance their ability to invade and migrate and promotes phosphorylation of Ezrin Tyr353.On the other hand, inhibition of Ezrin could reverse EGF-induced EMT and inhibit NF-kB P65 translocating into the nucleus. Finally, knockout of Ezrin inhibited EGF-induced lung metastasis of colorectal cancer xenografts and abnormal activation of Ezrin and NF-kB were related with colorectal cancer metastasis and poor prognosis. Our present results suggest that Ezrin/NF-kB pathway may provide experimental evidence for new targeted drugs for colorectal cancer metastasis.

Thrombomodulin Influences the Survival of Patients with Non-Metastatic Colorectal Cancer through Epithelial-To-Mesenchymal Transition (EMT)

Background

Treatment resistance and metastasis are the major causes of death among patients with colorectal cancer (CRC). Approximately 20% of surgically treated patients ultimately develop metastases during the follow-up period. Currently, the TNM system is the only available prognostic test. Therefore, the identification of new markers for CRC remains important. Thrombomodulin (TM), a glycoprotein, is involved in angiogenesis and has been linked to many malignant diseases. However, the function of TM in CRC remains unclear.

Methods

A total of 170 patients with CRC participated in this study. TM expression was analyzed via immunohistochemistry. Univariate (Kaplan-Meier) analysis was used to analyze patient outcomes, including overall survival (OS) and disease-free survival (DFS). TM expression was manipulated using shRNA or an overexpression system. Transwell migration assays, wound healing migration assays, and the xCELLigence biosensor system were used to detect cell proliferative and migratory capacities.

Results

TM expression in the tumor tissues significantly and positively correlated with the DFS and OS of non-metastatic patients with CRC (ps = 0.036 and 0.0218, respectively). Suppression of TM expression increased the proliferation and migration of DLD-1 cells. TM overexpression reduced the cells’ proliferative and migratory capacities. Cyclooxygenase (COX)-2 expression was up-regulated following TM silencing. Furthermore, the association between the migration of colon cancer cells and the levels of TM and epithelial-to-mesenchymal transition (EMT) markers (fibronectin, vimentin and ezrin) was confirmed in HT29 and DLD-1 cells.

Conclusions

Our study demonstrates that patients with non-metastatic CRC display low TM expression in their tumors and exhibit reduced DFS and OS. The enhanced expression of mesenchymal markers and COX-2 may be involved in the mechanisms that underlie recurrence in patients with cancer displaying low TM expression.

Cell Polarity Kinase MST4 Cooperates with cAMP-dependent Kinase to Orchestrate Histamine-stimulated Acid Secretion in Gastric Parietal Cells

The digestive function of the stomach depends on acidification of the gastric lumen. Acid secretion into the lumen is triggered by activation of the PKA cascade, which ultimately results in the insertion of gastric H,K-ATPases into the apical plasma membranes of parietal cells. A coupling protein is ezrin, whose phosphorylation at Ser-66 by PKA is required for parietal cell activation. However, little is known regarding the molecular mechanism(s) by which this signaling pathway operates in gastric acid secretion. Here we show that PKA cooperates with MST4 to orchestrate histamine-elicited acid secretion by phosphorylating ezrin at Ser-66 and Thr-567. Histamine stimulation activates PKA, which phosphorylates MST4 at Thr-178 and then promotes MST4 kinase activity. Interestingly, activated MST4 then phosphorylates ezrin prephosphorylated by PKA. Importantly, MST4 is important for acid secretion in parietal cells because either suppression of MST4 or overexpression of non-phosphorylatable MST4 prevents the apical membrane reorganization and proton pump translocation elicited by histamine stimulation. In addition, overexpressing MST4 phosphorylation-deficient ezrin results in an inhibition of gastric acid secretion. Taken together, these results define a novel molecular mechanism linking the PKA-MST4-ezrin signaling cascade to polarized epithelial secretion in gastric parietal cells.

Co-Expression of Ezrin-CLIC5-Podocalyxin Is Associated with Migration and Invasiveness in Hepatocellular Carcinoma

Background and Aim

Prognostic markers are important for predicting the progression and staging of hepatocellular carcinoma (HCC). Ezrin (EZR) and Podocalyxin (PODXL) are proteins associated with invasion, migration and poor prognosis in various types of cancer. Recently, it has been observed that chloride intracellular channel 5 (CLIC5) forms a complex with EZR and PODXL and that it is required for podocyte structure and function. In this study, we evaluated the overexpression of EZR, PODXL and CLIC5 in HCC.

Methods

The modified resistant hepatocyte model (MRHR), human biopsies and HCC cell lines (HepG2, Huh7 and SNU387) were used in this study. Gene and protein expression levels were evaluated in the MRHR by qRT-PCR, Western blot and immunohistochemistry analyses, and protein expression in the human biopsies was evaluated by immunohistochemistry. Protein expression in the HCC cell lines was evaluated by immunofluorescence and Western blot, also the migration and invasive abilities of Huh7 cells were evaluated using shRNA-mediated inhibition.

Results

Our results indicated that these genes and proteins were overexpressed in HCC. Moreover, when the expression of CLIC5 and PODXL was inhibited in Huh7 cells, we observed decreased migration and invasion.

Conclusion

This study suggested that EZR, CLIC5 and PODXL could be biological markers to predict the prognosis of HCC and that these proteins participate in migration and invasion processes.

12-O-Tetradecanoylphorbol-13-Acetate Induces Up-Regulated Transcription of Variant 1 but Not Variant 2 of VIL2 in Esophageal Squamous Cell Carcinoma Cells via ERK1/2/AP-1/Sp1 Signaling

The membrane-cytoskeleton link organizer ezrin may be the most "dramatic" tumor marker, being strongly over-expressed in nearly one-third of human malignancies. However, the molecular mechanisms of aberrant ezrin expression still need to be clarified. Ezrin, encoded by the VIL2 gene, has two transcript variants that differ in the transcriptional start site (TSS): V1 and V2. Both V1 and V2 encode the same protein. Here, we found that 12-O-tetradecanoylphorbol-13-acetate (TPA) induced over-expression of human VIL2 in esophageal squamous cell carcinoma (ESCC) cells. Furthermore, VIL2 V1 but not V2 was up-regulated after TPA stimulation in a time-dependent manner. AP-1 and Sp1 binding sites within the promoter region of VIL2 V1 acted not only as basal transcriptional elements but also as a composite TPA-responsive element (TRE) for the transcription of VIL2 V1. TPA stimulation enhanced c-Jun and Sp1 binding to the TRE via activation of the ERK1/2 pathway and increased protein levels of c-Jun, c-Fos, and Sp1, resulting in over-expression of VIL2 V1, whereas the MEK1/2 inhibitor U0126 blocked these events. Finally, we showed that TPA promoted the migration of ESCC cells whereas MEK1/2 inhibitor or ezrin silencing could partially inverse this alteration. Taken together, these results suggest that TPA is able to induce VIL2 V1 over-expression in ESCC cells by activating MEK/ERK1/2 signaling and increasing binding of Sp1 and c-Jun to the TRE of the VIL2 V1 promoter, and that VIL2 is an important TPA-induced effector.

Translational implication of Kallmann syndrome-1 gene expression in hepatocellular carcinoma

Accumulation of epigenetic alterations causes inactivation of tumor suppressors and contributes to the initiation and progression of hepatocellular carcinoma (HCC). Identification of methylated genes is necessary to improve our understanding of the pathogenesis of HCC and develop novel biomarkers and therapeutic targets. The Kallmann syndrome-1 (KAL1) gene encodes an extracellular matrix-related protein with diverse oncological functions. However, the function of KAL1 in HCC has not been examined. We investigated the methylation status of the KAL1 promoter region in HCC cell lines, and evaluated KAL1 mRNA levels and those of genes encoding potential interacting cell adhesion factors. KAL1 mRNA expression level was heterogeneous in nine HCC cell lines, and reactivation of KAL1 mRNA expression was observed in cells with promoter hypermethylation of KAL1 gene after demethylation. In addition, KAL1 mRNA levels inversely correlated with those of ezrin in all nine HCC cell lines. KAL1 expression levels in 144 pairs of surgically-resected tissues were determined and correlated to clinicopathological parameters. KAL1 mRNA level was independent of the background liver status, whereas HCC tissues showed significantly lower KAL1 mRNA levels than corresponding noncancerous liver tissues. Downregulation of KAL1 mRNA in HCC was significantly associated with malignant phenotype characteristics, including elevated tumor markers, larger tumor size, vascular invasion, and hypermethylation of KAL1. Patients with downregulation of KAL1 were more likely to have a shorter overall survival than other patients, and multivariate analysis identified downregulation of KAL1 as an independent prognostic factor (hazard ratio 2.04, 95% confidence interval 1.11-3.90, P=0.022). Our results indicated that KAL1 may act as a putative tumor suppressor in HCC and is inactivated by promoter hypermethylation. KAL1 may serve as a biomarker of malignant phenotype of HCC.

Identification of Ezrin-Radixin-Moesin proteins as novel regulators of pathogenic B-cell receptor signaling and tumor growth in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is a hematological cancer associated with an aggressive clinical course. The predominant subtypes of DLBCL display features of chronic or tonic B-cell antigen receptor (BCR) signaling. However, it is not known whether the spatial organization of the BCR contributes to the regulation of pro-survival signaling pathways and cell growth. Here, we show that primary DLBCL tumors and patient-derived DLBCL cell lines contain high levels of phosphorylated Ezrin-Radixin-Moesin (ERM) proteins. The surface BCRs in both activated B cell and germinal B cell subtype DLBCL cells co-segregate with phosphoERM suggesting that the cytoskeletal network may support localized BCR signaling and contribute to pathogenesis. Indeed, ablation of membrane-cytoskeletal linkages by dominant-negative mutants, pharmacological inhibition and knockdown of ERM proteins disrupted cell surface BCR organization, inhibited proximal and distal BCR signaling, and reduced the growth of DLBCL cell lines. In vivo administration of the ezrin inhibitor retarded the growth of DLBCL tumor xenografts, concomitant with reduction in intratumor phosphoERM levels, dampened pro-survival signaling and induction of apoptosis. Our results reveal a novel ERM-based spatial mechanism that is coopted by DLBCL cells to sustain tumor cell growth and survival.

Desmoglein 3: a help or a hindrance in cancer progression?

Desmoglein 3 is one of seven desmosomal cadherins that mediate cell-cell adhesion in desmosomes. Desmosomes are the intercellular junctional complexes that anchor the intermediate filaments of adjacent cells and confer strong cell adhesion thus are essential in the maintenance of tissue architecture and structural integrity. Like adherens junctions, desmosomes function as tumour suppressors and are down regulated in the process of epithelial-mesenchymal transition and in tumour cell invasion and metastasis. However, recently several studies have shown that various desmosomal components, including desmoglein 3, are up-regulated in cancer with increased levels of expression correlating with the clinical stage of malignancy, implicating their potentiality to serve as a diagnostic and prognostic marker. Furthermore, in vitro studies have demonstrated that overexpression of desmoglein 3 in cancer cell lines activates several signal pathways that have an impact on cell morphology, adhesion and locomotion. These additional signalling roles of desmoglein 3 may not be associated to its adhesive function in desmosomes but rather function outside of the junctions, acting as a key regulator in the control of actin based cellular processes. This review will discuss recent advances which support the role of desmoglein 3 in cancer progression.

Malignant fibrous histiocytoma of visceral organs: clinicopathologic features and diagnostic value of ezrin and HMG-CoA reductase

Malignant fibrous histiocytoma (MFH) of the breast and visceral organs is extremely rare. There is an incomplete understanding of the clinical pathology of the primary MFH originating from the breast and visceral organs, especially in comparison with other soft tissue sarcomas. As a consequence we searched and analyzed the clinical and pathological records of all the nine patients with diagnosed breast and visceral MFH in our hospital. Immunohistochemical staining was performed for ezrin and HMG-CoA reductase in these MFH cases and relevant mesenchymal sarcomas. The 9 MFH cases presented with nonspecific symptoms and imaging manifestations. 6 cases were classified as storiform-pleomorphic MFH, 2 cases as inflammatory MFH, and the remaining 1 case as giant cell MFH. The results showed that ezrin expression, as well as HMG-CoA reductase expression, was significantly stronger in MFH cases than other non-MFH sarcomas. Poor prognosis seemed to be associated with younger age. Certain characteristics and clinicopathologic features can help us making the diagnosis of MFH. In conclusion, our study provided the potential value of ezrin and HMG-CoA reductase for diagnosis and differential diagnosis of MFH located in the breast and visceral organs. More accurate prognostic information of this rare disease needed to be further investigated.

Spatial control of proton pump H,K-ATPase docking at the apical membrane by phosphorylation-coupled ezrin-syntaxin 3 interaction

The digestive function of the stomach depends on acidification of the gastric lumen. Acid secretion into the lumen is triggered by activation of a cAMP-dependent protein kinase (PKA) cascade, which ultimately results in the insertion of gastric H,K-ATPases into the apical plasma membranes of parietal cells. A coupling protein is ezrin whose phosphorylation at Ser-66 by PKA is required for parietal cell activation. However, little is known regarding the molecular mechanism(s) by which ezrin operates in gastric acid secretion. Here we show that phosphorylation of Ser-66 induces a conformational change of ezrin that enables its association with syntaxin 3 (Stx3) and provides a spatial cue for H,K-ATPase trafficking. This conformation-dependent association is specific for Stx3, and the binding interface is mapped to the N-terminal region. Biochemical analyses show that inhibition of ezrin phosphorylation at Ser-66 prevents ezrin-Stx3 association and insertion of H,K-ATPase into the apical plasma membrane of parietal cells. Using atomic force microscopic analyses, our study revealed that phosphorylation of Ser-66 induces unfolding of ezrin molecule to allow Stx3 binding to its N terminus. Given the essential role of Stx3 in polarized secretion, our study presents the first evidence in which phosphorylation-induced conformational rearrangement of the ezrin molecule provides a spatial cue for polarized membrane trafficking in epithelial cells.

USP22 promotes epithelial-mesenchymal transition via the FAK pathway in pancreatic cancer cells

Epithelial-mesenchymal transition (EMT) contributes to the occurrence and development of tumors, particularly to the promotion of tumor invasion and metastasis. As a newly discovered ubiquitin hydrolase family member, USP22 plays a key role in the malignant transformation of tumors and the regulation of the cell cycle. However, recent studies on USP22 have primarily focused on its role in cell cycle regulation, and the potential mechanism underlying the promotion of tumor invasion and metastasis by abnormal USP22 expression has not been reported. Our studies revealed that the overexpression of USP22 in PANC-1 cells promoted Ezrin redistribution and phosphorylation and cytoskeletal remodeling, upregulated expression of the transcription factors Snail and ZEB1 to promote EMT, and increased cellular invasion and migration. In contrast, blockade of USP22 expression resulted in the opposite effects. In addition, the focal adhesion kinase (FAK) signaling pathway was shown to play a key role in the process of EMT induction in PANC-1 cells by USP22. Thus, the present study suggests that USP22 acts as a regulatory protein for EMT in pancreatic cancer, which may provide a new approach for the targeted therapy of pancreatic cancer.

MicroRNA-204, a direct negative regulator of ezrin gene expression, inhibits glioma cell migration and invasion

Ezrin is overexpressed in a variety of neoplastic cells and involved in the later stages of tumor progression and metastasis. Ezrin expression can be regulated at both the transcriptional and post-transcriptional levels. We used a combination of bioinformatics and experimental techniques to demonstrate that the miR-204 is a direct negative regulator of ezrin. Overexpression of miR-204 mimics decreased the activity of a luciferase reporter containing the ezrin 3' UTR and led to repression of ezrin protein. In contrast, ectopic expression of miR-204 inhibitor elevated ezrin expression. We also show that miR-204 is down-regulated in a panel of glioma tissues and in high invasive glioma cell lines we examined. Moreover, miR-204 mimics significantly reduced glioma cell migration and invasion, while miR-204 inhibitor generated the opposite results. Finally, overexpression of miR-204 and knockdown of ezrin reduced glioma cell invasion, and these effects could be rescued by re-expression of ezrin. These findings reveal that miR-204 could be partly due to its inhibitory effects on glioma cell migration and invasion through regulating ezrin expression.

Targeting Rho-GTPases in immune cell migration and inflammation

Leukocytes are unmatched migrators capable of traversing barriers and tissues of remarkably varied structural composition. An effective immune response relies on the ability of its constituent cells to infiltrate target sites. Yet, unwarranted mobilization of immune cells can lead to inflammatory diseases and tissue damage ranging in severity from mild to life-threatening. The efficacy and plasticity of leukocyte migration is driven by the precise spatiotemporal regulation of the actin cytoskeleton. The small GTPases of the Rho family (Rho-GTPases), and their immediate downstream effector kinases, are key regulators of cellular actomyosin dynamics and are therefore considered prime pharmacological targets for stemming leukocyte motility in inflammatory disorders. This review describes advances in the development of small-molecule inhibitors aimed at modulating the Rho-GTPase-centric regulatory pathways governing motility, many of which stem from studies of cancer invasiveness. These inhibitors promise the advent of novel treatment options with high selectivity and potency against immune-mediated pathologies.

Ezrin expression and cell survival regulation in colorectal cancer

Colorectal cancer (CRC) is the second largest cause of cancer deaths in the United States. A key barrier that prevents better outcomes for this type of cancer as well as other solid tumors is the lack of effective therapies against the metastatic disease. Thus there is an urgent need to fill this gap in cancer therapy. We utilized a 2D-DIGE proteomics approach to identify and characterize proteins that are differentially regulated between primary colon tumor and liver metastatic deposits of the IGF1R-dependent GEO human CRC xenograft, orthotopically implanted in athymic nude mice that may serve as potential therapeutic targets against CRC metastasis. We observed increased expression of ezrin in liver metastasis in comparison to the primary colonic tumor. Increased ezrin expression was further confirmed by western blot and microarray analyses. Ezrin, a cytoskeletal protein belonging to Ezrin-Radixin-Moesin (ERM) family plays important roles in cell motility, invasion and metastasis. However, its exact function in colorectal cancer is not well characterized. Establishment of advanced GEO cell lines with enhanced liver-metastasizing ability showed a significant increase in ezrin expression in liver metastasis. Increased phosphorylation of ezrin at the T567 site (termed here as p-ezrin T567) was observed in liver metastasis. IHC studies of human CRC patient specimens showed an increased expression of p-ezrin T567 in liver metastasis compared to the primary tumors of the same patient. Ezrin modulation by siRNA, inhibitors and T567A/D point mutations significantly downregulated inhibitors of apoptosis (IAP) proteins XIAP and survivin that have been linked to increased aberrant cell survival and metastasis and increased cell death. Inhibition of the IGF1R signaling pathway by humanized recombinant IGF1R monoclonal antibody MK-0646 in athymic mouse subcutaneous xenografts resulted in inhibition of p-ezrin T567 indicating ezrin signaling is downstream of the IGF1R signaling pathway. We identified increased expression of p-ezrin T567 in CRC liver metastasis in both orthotopically implanted GEO tumors as well as human patient specimens. We report for the first time that p-ezrin T567 is downstream of the IGF1R signaling and demonstrate that ezrin regulates cell survival through survivin/XIAP modulation.

Prognostic implications of ezrin and phosphorylated ezrin expression in non-small cell lung cancer

BACKGROUND

The cytoskeletal organizer ezrin is a member of the ezrin-radixin-moesin (ERM) family and plays important roles in not only cell motility, cell adhesion, and apoptosis, but also in various cell signaling pathways. Phosphorylation at Thr-567 and Tyr-353 are key regulatory events in the transition of the dormant to active form of ezrin. This study investigated the prognostic implications of ezrin and phosphorylated ezrin (p-ezrin) expression in non-small cell lung carcinoma (NSCLC).

METHODS

Ezrin and p-ezrin protein expressions were examined by immunohistochemistry in 150 NSCLC and adjacent non-tumor tissues and 14 normal lung tissues. qRT-PCR was used to determine ezrin mRNA expression levels in fresh tissues. The correlations between overexpression of ezrin and p-ezrin and the clinicopathological features of NSCLC were analyzed. The survival rates were calculated by the Kaplan-Meier method for 108 NSCLC cases.

RESULTS

Ezrin and ezrinThr-567 proteins showed cytosolic and membranous staining patterns; however, ezrinTyr-353 protein only showed cytosolic staining. Ezrin and p-ezrin were significantly upregulated in NSCLC compared with the normal counterparts. Increased ezrin, ezrinThr-567, and ezrinTyr-353 levels were correlated with the late stage and poor differentiation of NSCLC. However, only ezrinThr-567 was correlated with the presence of lymph node metastasis. In regard to survival, only ezrinThr-567 was related with the overall survival time of patients with NSCLC, and both ezrin and ezrinThr-567 were associated with shortened survival time for patients with early stage NSCLC.

CONCLUSIONS

Ezrin and p-ezrin, especially ezrinThr-567, may prove to be useful as a novel prognostic biomarker of NSCLC.

Akt inhibitor MK-2206 promotes anti-tumor activity and cell death by modulation of AIF and Ezrin in colorectal cancer

BACKGROUND

There is extensive evidence for the role of aberrant cell survival signaling mechanisms in cancer progression and metastasis. Akt is a major component of cell survival-signaling mechanisms in several types of cancer. It has been shown that activated Akt stabilizes XIAP by S87 phosphorylation leading to survivin/XIAP complex formation, caspase inhibition and cytoprotection of cancer cells. We have reported that TGFβ/PKA/PP2A-mediated tumor suppressor signaling regulates Akt phosphorylation in association with the dissociation of survivin/XIAP complexes leading to inhibition of stress-dependent induction of cell survival.

METHODS

IGF1R-dependent colon cancer cells (GEO and CBS) were used for the study. Effects on cell proliferation and cell death were determined in the presence of MK-2206. Xenograft studies were performed to determine the effect of MK-2206 on tumor volume. The effect on various cell death markers such as XIAP, survivin, AIF, Ezrin, pEzrin was determined by western blot analysis. Graph pad 5.0 was used for statistical analysis. P < 0.05 was considered significant.

RESULTS

We characterized the mechanisms by which a novel Akt kinase inhibitor MK-2206 induced cell death in IGF1R-dependent colorectal cancer (CRC) cells with upregulated PI3K/Akt signaling in response to IGF1R activation. MK-2206 treatment generated a significant reduction in tumor growth in vivo and promoted cell death through two mechanisms. This is the first report demonstrating that Akt inactivation by MK-2206 leads to induction of and mitochondria-to-nuclear localization of the Apoptosis Inducing Factor (AIF), which is involved in caspase-independent cell death. We also observed that exposure to MK-2206 dephosphorylated Ezrin at the T567 site leading to the disruption of Akt-pEzrin-XIAP cell survival signaling. Ezrin phosphorylation at this site has been associated with malignant progression in solid tumors.

CONCLUSION

The identification of these 2 novel mechanisms leading to induction of cell death indicates MK-2206 might be a potential clinical candidate for therapeutic targeting of the subset of IGF1R-dependent cancers in CRC.

NHERF2 is crucial in ERM phosphorylation in pulmonary endothelial cells

Background

EBP50 and NHERF2 adaptor proteins are incriminated in various signaling pathways of the cell. They can bind ERM proteins and mediate ERM-membrane protein interactions.

Results

Binding of ERM to EBP50 and NHERF2 was compared in pulmonary artery endothelial cells by immunoprecipitation. NHERF2 associates with all three ERM, but EBP50 appeared to be a weak binding partner if at all. Furthermore, we detected co-localization of NHERF2 and phospho-ERM at the cell membrane and in the filopodia of dividing cells. Silencing of NHERF2 prevented agonist or angiogenesis induced phosphorylation of ERM, while overexpression of the adaptor elevated the phosphorylation level of ERM, likely catalyzed by Rho kinase 2, which co-immunoprecipitated with NHERF2/ERM in control EC, but did not bind to ERM in NHERF2 depleted cells. Dependence of ERM phosphorylation on NHERF2 was also shown in Matrigel tube formation assay, and NHERF2 was proved to be important in angiogenesis as well. Furthermore, when NHERF2 was depleted or cells were overexpressing a mutant form of NHERF2 unable to bind ERM, we found attenuated cell attachment with ECIS measurements, while it was supported by overexpression of wild type NHERF2.

Conclusions

Pivotal role of NHERF2 in the phosphorylation process of ERM in pulmonary artery endothelial cells is shown. We propose that NHERF2 provides a common anchoring surface for ERM and Rho kinase 2. Our results demonstrate the essential role of NHERF2 in endothelial cell adhesion/migration and angiogenesis.

Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis in tongue squamous cell carcinoma

BACKGROUND

Epithelial-mesenchymal transition (EMT) is a crucial programme in cancer metastasis. Epidermal growth factor (EGF) is a key inducer of EMT, and Ezrin has an important role in this process. However, how Ezrin is activated and whether it mediates EGF-induced EMT in tongue squamous cell carcinomas (TSCCs) through activating NF-κB remains obscure.

METHODS

We used two TSCC cell lines as a cell model to study invasion and EMT in vitro, and used nude mice xenografts model to evaluate metastasis of TSCC cells. Finally, we evaluated the level of pEzrin Tyr353, nuclear p65 and EMT markers in TSCC clinical samples.

RESULTS

Ezrin Tyr353 was phosphorylated through Akt (but not ERK1/2, ROCK1) pathway, and lead to the activation of NF-κB in EGF-treated TSCC cells. Akt and NF-κB inhibitors blocked EGF-induced EMT, and suppressed invasion and migration of TSCC cells. In vivo, silencing Ezrin significantly suppressed EGF-enhanced metastasis of TSCC xenografts. Finally, high levels of expression of pEzrin Tyr353, nuclear p65, vimentin and low level of expression of E-cadherin were correlated with cancer metastasis and poor patient prognosis.

CONCLUSION

Our data suggest that Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis inTSCC, and Ezrin may serve as a therapeutic target to reverse EMT in tongue cancers and prevent TSCC progression.

Ezrin expression is an independent prognostic factor in gastro-intestinal cancers

BACKGROUND

Ezrin, a member of the ezrin-radixin-moesin (ERM) family of plasma membrane-cytoskeleton linker proteins, has been associated with metastatic behavior.

METHODOLOGY

Microarrayed pathological tissues of surgically resected colorectal cancer liver metastasis (CRLM) and whole tissue sections of cancer of the ampulla of Vater (CAV) were analyzed to determine ezrin expression levels and correlation with survival. The requirement of ezrin in invasive capability was assessed using in vitro assays.

RESULTS

Surgically resected CAV showing a low ezrin score have a better 5-year disease-specific survival than those showing a high ezrin score (P < 0.0001). Similarly, high ezrin expression at the invasive front of CRLM resulted in poor disease-free survival (P = 0.05). Multivariate analysis demonstrated high ezrin expression to be an independent adverse prognostic factor for CAV (hazard ratio (HR) 15.22 (95 % confidence interval (CI) 1.98-117.03), P < 0.01) and CRLM (HR 6.42 (95 % CI 1.01-52.43), P = 0.05), among other clinically relevant variables such as lymph node metastasis (for CAV) and the presence of extrahepatic disease, large hepatic metastases (>5 cm), and close surgical resection margins (<5 mm) (all for CRLM). In vitro experiments indicated that ezrin expression was vital for cellular processes such as adhesive and invasive activity.

SIGNIFICANCE

High ezrin expression indicates an adverse prognosis in primary CAV and CRLM.