High level of ezrin expression in colorectal cancer tissues is closely related to tumor malignancy

Ezrin Inhibition Overcomes Acquired Resistance to Vemurafenib in BRAFV600E-Mutated Colon Cancer and Melanoma Cells In Vitro

Despite the advancements in targeted therapy for BRAFV600E-mutated metastatic colorectal cancer (mCRC), the development of resistance to BRAFV600E inhibition limits the response rate and durability of the treatment. Better understanding of the resistance mechanisms to BRAF inhibitors will facilitate the design of novel pharmacological strategies for BRAF-mutated mCRC. The aim of this study was to identify novel protein candidates involved in acquired resistance to BRAFV600E inhibitor vemurafenib in BRAFV600E-mutated colon cancer cells using an integrated proteomics approach. Bioinformatic analysis of obtained proteomics data indicated actin-cytoskeleton linker protein ezrin as a highly ranked protein significantly associated with vemurafenib resistance whose overexpression in the resistant cells was additionally confirmed at the gene and protein level. Ezrin inhibition by NSC305787 increased anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant cells in an additive manner, which was accompanied by downregulation of CD44 expression and inhibition of AKT/c-Myc activities. We also detected an increased ezrin expression in vemurafenib-resistant melanoma cells harbouring the BRAFV600E mutation. Importantly, ezrin inhibition potentiated anti-proliferative and pro-apoptotic effects of vemurafenib in the resistant melanoma cells in a synergistic manner. Altogether, our study suggests a role of ezrin in acquired resistance to vemurafenib in colon cancer and melanoma cells carrying the BRAFV600E mutation and supports further pre-clinical and clinical studies to explore the benefits of combined BRAF inhibitors and actin-targeting drugs as a potential therapeutic approach for BRAFV600E-mutated cancers.

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.

Epithelial-to-Mesenchymal Plasticity in Circulating Tumor Cell Lines Sequentially Derived from a Patient with Colorectal Cancer

Simple Summary

Metastasis is a complex dynamic multistep process; however, our knowledge is still limited. Very few circulating tumor cells (CTCs) are metastatic precursor cells and represent the intermediate stage of metastasis. Epithelial–mesenchymal plasticity (EMP) has crucial roles in tissue development and homeostasis, and also in metastasis formation. In this study, we explored the EMP phenotype of a unique series of CTC lines, obtained from a patient with colon cancer during the disease course and treatment, by detecting markers involved in the epithelial–mesenchymal and mesenchymal–epithelial (MET) transitions. This study shows that these colon CTC lines have acquired only few mesenchymal features to migrate and intravasate, whereas an increase of MET-related markers was observed, suggesting that metastasis-competent CTCs need to revert quickly to the epithelial phenotype to reinitiate a tumor at a distant site.

Abstract

Metastasis is a complicated and only partially understood multi-step process of cancer progression. A subset of cancer cells that can leave the primary tumor, intravasate, and circulate to reach distant organs are called circulating tumor cells (CTCs). Multiple lines of evidence suggest that in metastatic cancer cells, epithelial and mesenchymal markers are co-expressed to facilitate the cells’ ability to go back and forth between cellular states. This feature is called epithelial-to-mesenchymal plasticity (EMP). CTCs represent a unique source to understand the EMP features in metastatic cascade biology. Our group previously established and characterized nine serial CTC lines from a patient with metastatic colon cancer. Here, we assessed the expression of markers involved in epithelial–mesenchymal (EMT) and mesenchymal–epithelial (MET) transition in these unique CTC lines, to define their EMP profile. We found that the oncogenes MYC and ezrin were expressed by all CTC lines, but not SIX1, one of their common regulators (also an EMT inducer). Moreover, the MET activator GRHL2 and its putative targets were strongly expressed in all CTC lines, revealing their plasticity in favor of an increased MET state that promotes metastasis formation.

Bidirectional Tumor-Promoting Activities of Macrophage Ezrin

Ezrin links the cytoskeleton to cell surface integrins and plasma membrane receptors, contributing to the proliferative and metastatic potential of cancer cells. Elevated ezrin expression in several cancers is associated with poor outcomes. Tumor cell ezrin expression and function have been investigated in depth; however, its role in macrophages and other tumor microenvironment cells remains unexplored. Macrophages profoundly influence tumorigenesis, and here we explore ezrin’s influence on tumor-promoting macrophage functions. Ezrin knockdown in THP-1 macrophages reveals its important contribution to adhesion to endothelial cells. Unexpectedly, ezrin is essential for the basal and breast cancer cell-stimulated THP-1 expression of ITGAM mRNA that encodes integrin CD11b, critical for cell adhesion. Ezrin skews the differentiation of THP-1 macrophages towards the pro-tumorigenic, M2 subtype, as shown by the reduced expression of FN1, IL10, and CCL22 mRNAs following ezrin knockdown. Additionally, macrophage ezrin contributes to the secretion of factors that stimulate tumor cell migration, invasion, and clonogenic growth. Lastly, THP-1 ezrin is critical for the expression of mRNAs encoding vascular endothelial growth factor (VEGF)-A and matrix metalloproteinase (MMP)-9, consistent with pro-tumorigenic function. Collectively, our results provide insight into ezrin’s role in tumorigenesis, revealing a bidirectional interaction between tumor-associated macrophages and tumor cells, and suggest myeloid cell ezrin as a target for therapeutic intervention against cancer.

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.

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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Pancreatic cancer-derived small extracellular vesical Ezrin regulates macrophage polarization and promotes metastasis

Small extracellular vesicles (sEVs) mediate the interaction between tumor and tumor-associated macrophages (TAMs). This study aims to demonstrate that the pancreatic ductal adenocarcinoma (PDAC)-derived sEV Ezrin (sEV-EZR) could modulate macrophage polarization and promote PDAC metastasis. We isolated PDAC-derived sEVs and plasma sEVs from PDAC patients. Human blood mononuclear cell (PBMC)-derived macrophages were treated with PDAC-derived sEVs or the counterpart depleted Ezrin (EZR) with shRNA-mediated knockdown. We used enzyme-linked immunosorbent assays and flow cytometry to monitor macrophages polarization. NOD/SCID/IL2Rγ^null mice were treated with sEVs to study PDAC liver metastasis. The plasma sEV-EZR levels of 165 PDAC patients and 151 high-risk controls were analyzed. The EZR levels are higher in sEVs derived from PDAC cells and PDAC-patient plasma than that of the normal controls. PDAC-derived sEVs modulate the polarization of macrophages to M2 phenotype, while PDAC-shEZR-derived sEVs polarize macrophages into M1 phenotype. We found an increase in M1 TAMs and a decrease in M2 TAMs in orthotropic tumors treated with PDAC-shEZR-derived sEVs. The amount of liver metastasis in PDAC-shEZR-derived sEVs-treated mice was observed to be smaller than that of controls. The mean plasma sEV-EZR levels from PDAC patients were significantly higher than those from the controls (32.43±20.78 vs. 21.88±11.43 pg/ml; P<0.0001). The overall survival in the high-plasma sEV-EZR patients was significantly shorter than that in the low-EZR group (6.94±15.25 vs. 9.63±15.11 months; P=0.0418). sEV-EZR could modulate macrophage polarization and promote metastasis in PDAC. Targeting sEV-EZR can be considered a promising therapeutic strategy to inhibit PDAC metastasis.

High expression of EZR (ezrin) gene is correlated with the poor overall survival of breast cancer patients

Background

To evaluate the EZR (ezrin) gene expression in breast cancer and correlation with the prognosis through bioinformatics analysis and immunohistochemistry assay.

Methods

EZR gene expression in breast cancer and corresponding normal breast tissue was compared in the TCGA database. Protein‐protein interaction (PPI) network relevant EZR was established through the STRING database. The correlation between EZR expression and prognosis of breast cancer was analyzed by the log‐rank analysis from the TCGA. Ezrin protein (coded by EZR) expression was also examined by immunohistochemistry assay in 120 breast cancer patients.

Results

EZR expression level in tumor tissue was significantly upregulated compared to that of normal breast tissue of breast cancer patients (P < 0.05). In the PPI analysis, there were 51 nodes and 455 edges in the network. The top 10 hub genes of the network were identified. High expression of EZR mRNA was correlated with poor overall survival (OS) of the breast cancer patients (HR = 1.40, P = 0.038). However, the disease‐free survival (DFS) of breast cancer patients did not correlate with the EZR mRNA level (HR = 0.86, P = 0.44). The ezrin protein expression was positive with uniform brown‐yellow granules in the cell membrane, cavity surface and cytoplasm of the breast cancer cells. Of the included 120 cancer samples, 98 cases were positive for ezrin expression and 22 were negative. No correlation was found between ezrin expression site and patients’ clinicopathological features.

Conclusion

EZR is upregulated in breast cancer and can be used as potential biomarker for overall survival.

Role of phospho-ezrin in differentiating thyroid carcinoma

Comprehensive theory explaining the relationship between estrogen (E2) and ezrin in metastasis of thyroid cancer remains non-elicited. In vitro results revealed that E2 could stimulate the expression and phosphorylation of ezrin in a time and dose dependent manner. Our data clearly showed that E2 enhanced the migration and invasion of cells, which was reversed by the transfection of cells with ezrin specific siRNA. Further, we observed that Phosphoinositide 3-kinase (PI3K) ROCK-2 are among the kinases responsible for E2 induced phosphorylation of ezrin. Clinical validation of ezrin/phospho-ezrin revealed that phospho-ezrin was intensely expressed in follicular thyroid carcinoma (FTC) and follicular variant of papillary thyroid carcinoma (FVPTC), while it was completely absent in follicular adenoma (FA) lesions in which the differentiation of the follicular neoplasms remains subtle. When histology of different carcinomas is correlated with benign FA with respect to phospho-ezrin, we observed that the marker was highly significant (p = 0.0001). 100% sensitivity, specificity and diagnostic accuracy of the above marker in the histological association of FTC, FVPTC with FA, enables us to suggest phospho-ezrin as a diagnostic marker to differentiate the follicular neoplasms. These data are the first to suggest the dynamic regulation of ezrin phosphorylation during metastasis in FTC.

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.

Successful identification of a predictive biomarker for lymph node metastasis in colorectal cancer using a proteomic approach

Colorectal cancer (CRC)-associated mortality is primarily caused by lymph node (LN) and distant metastasis, highlighting the need for biomarkers that predict LN metastasis and facilitate better therapeutic strategies. We used an Isobaric Tags for Relative and Absolute Quantification (iTRAQ)-based comparative proteomics approach to identify novel biomarkers for predicting LN metastasis in CRC patients. We analyzed five paired samples of CRC with or without LN metastasis, adjacent normal mucosa, and normal colon mucosa, and differentially expressed proteins were identified and subsequently validated at the protein and/or mRNA levels by immunohistochemistry and qRT-PCR, respectively. We identified 55 proteins specifically associated with LN metastasis, from which we selected ezrin for further analysis and functional assessment. Expression of ezrin at both the protein and mRNA levels was significantly higher in CRC tissues than in adjacent normal colonic mucosa. In univariate analysis, high ezrin expression was significantly associated with tumor progression and poor prognosis, which was consistent with our in vitro findings that ezrin promotes the metastatic capacity of CRC cells by enabling cell invasion and migration. In multivariate analysis, high levels of ezrin protein and mRNA in CRC samples were independent predictors of LN metastasis. Our data thus identify ezrin as a novel protein and mRNA biomarker for predicting LN metastasis in CRC patients.

Association of Ezrin expression with the progression and prognosis of gastrointestinal cancer: a meta-analysis

Background

Ezrin, a cytoskeletal protein, is involved in cell adhesion. Several studies have been performed to explore the association between Ezrin and gastrointestinal cancers, but the results are inconclusive. This meta-analysis aims to assess the prognostic value of Ezrin.

Materials and Methods/Findings

PubMed and EMBASE were searched. Pooled hazard ratio (HR), odds ratio (OR) and 95% confidence intervals (CI) were utilized to evaluate the association between Ezrin expression and various clinical parameters. 2701 patients from 19 studies were included in the meta-analysis. For gastric cancer, Ezrin expression was associated with tumor grade (OR 2.32, 95% CI 1.53-3.52), TNM stage (OR 4.69, 95% CI 1.38-15.89), lymph node involvement (OR 3.96, 95% CI 1.47-10.70) and overall survival (HR 1.88, 95% CI 1.33-2.66). In colorectal cancer, Ezrin expression was associated with tumor grade (OR 3.94, 95% CI 2.10-3.78), TNM stage (OR 5.66, 95% CI 1.41-22.67), lymph node metastasis (OR 9.52, 95% CI 3.93-23.02), distant metastasis (OR 3.06, 95% CI 1.77-5.31), disease free survival (HR 2.48, 95% CI 1.44-4.28). For esophageal cancer, Ezrin expression was associated with lymph node metastasis (OR 2.07, 95% CI 1.00-4.28) and overall survival (HR 1.49, 95% CI 1.17-1.89).

Conclusions

Ezrin expression is significantly associated with tumor grade, TNM stage, and lymph node metastasis in gastric and colorectal cancers. For gastric cancers, Ezrin is useful in predicting distant metastasis. Survival data showed that high Ezrin expression is associated with poor prognosis in gastric, colorectal and esophageal cancers. Our findings suggest that Ezrin might be a potential biomarker in several gastrointestinal cancers.

In-depth N-glycome profiling of paired colorectal cancer and non-tumorigenic tissues reveals cancer-, stage- and EGFR-specific protein N-glycosylation

Glycomics may assist in uncovering the structure-function relationships of protein glycosylation and identify glycoprotein markers in colorectal cancer (CRC) research. Herein, we performed label-free quantitative glycomics on a carbon-liquid chromatography-tandem mass spectrometry-based analytical platform to accurately profile the N-glycosylation changes associated with CRC malignancy. N-Glycome profiling was performed on isolated membrane proteomes of paired tumorigenic and adjacent non-tumorigenic colon tissues from a cohort of five males (62.6 ± 13.1 y.o.) suffering from colorectal adenocarcinoma. The CRC tissues were typed according to their epidermal growth factor receptor (EGFR) status by western blotting and immunohistochemistry. Detailed N-glycan characterization and relative quantitation identified an extensive structural heterogeneity with a total of 91 N-glycans. CRC-specific N-glycosylation phenotypes were observed including an overrepresentation of high mannose, hybrid and paucimannosidic type N-glycans and an under-representation of complex N-glycans (P < 0.05). Sialylation, in particular α2,6-sialylation, was significantly higher in CRC tumors relative to non-tumorigenic tissues, whereas α2,3-sialylation was down-regulated (P < 0.05). CRC stage-specific N-glycosylation was detected by high α2,3-sialylation and low bisecting β1,4-GlcNAcylation and Lewis-type fucosylation in mid-late relative to early stage CRC. Interestingly, a novel link between the EGFR status and the N-glycosylation was identified using hierarchical clustering of the N-glycome profiles. EGFR-specific N-glycan signatures included high bisecting β1,4-GlcNAcylation and low α2,3-sialylation (both P < 0.05) relative to EGFR-negative CRC tissues. This is the first study to correlate CRC stage and EGFR status with specific N-glycan features, thus advancing our understanding of the mechanisms causing the biomolecular deregulation associated with CRC.

Quantitative proteomic analysis of paired colorectal cancer and non-tumorigenic tissues reveals signature proteins and perturbed pathways involved in CRC progression and metastasis

Modern proteomics has proven instrumental in our understanding of the molecular deregulations associated with the development and progression of cancer. Herein, we profile membrane-enriched proteome of tumor and adjacent normal tissues from eight CRC patients using label-free nanoLC-MS/MS-based quantitative proteomics and advanced pathway analysis. Of the 948 identified proteins, 184 proteins were differentially expressed (P<0.05, fold change>1.5) between the tumor and non-tumor tissue (69 up-regulated and 115 down-regulated in tumor tissues). The CRC tumor and non-tumor tissues clustered tightly in separate groups using hierarchical cluster analysis of the differentially expressed proteins, indicating a strong CRC-association of this proteome subset. Specifically, cancer associated proteins such as FN1, TNC, DEFA1, ITGB2, MLEC, CDH17, EZR and pathways including actin cytoskeleton and RhoGDI signaling were deregulated. Stage-specific proteome signatures were identified including up-regulated ribosomal proteins and down-regulated annexin proteins in early stage CRC. Finally, EGFR(+) CRC tissues showed an EGFR-dependent down-regulation of cell adhesion molecules, relative to EGFR(-) tissues. Taken together, this study provides a detailed map of the altered proteome and associated protein pathways in CRC, which enhances our mechanistic understanding of CRC biology and opens avenues for a knowledge-driven search for candidate CRC protein markers.

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.

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.

Decreased tumor progression and invasion by a novel anti-cell motility target for human colorectal carcinoma cells

We have previously described a novel modulator of the actin cytoskeleton that also regulates Ras and mitogen-activated protein kinase activities in TGFβ-sensitive epithelial cells. Here we examined the functional role of this signaling regulatory protein (km23-1) in mediating the migration, invasion, and tumor growth of human colorectal carcinoma (CRC) cells. We show that small interfering RNA (siRNA) depletion of km23-1 in human CRC cells inhibited constitutive extracellular signal-regulated kinase (ERK) activation, as well as pro-invasive ERK effector functions that include phosphorylation of Elk-1, constitutive regulation of c-Fos-DNA binding, TGFβ1 promoter transactivation, and TGFβ1 secretion. In addition, knockdown of km23-1 reduced the paracrine effects of CRC cell-secreted factors in conditioned medium and in fibroblast co-cultures. Moreover, km23-1 depletion in human CRC cells reduced cell migration and invasion, as well as expression of the ERK-regulated, metastasis-associated scaffold protein Ezrin. Finally, km23-1 inhibition significantly suppressed tumor formation in vivo. Thus, our results implicate km23-1 as a novel anti-metastasis target for human colon carcinoma cells, capable of decreasing tumor growth and invasion via a mechanism involving suppression of various pro-migratory features of CRC. These include a reduction in ERK signaling, diminished TGFβ1 production, decreased expression of the plasma membrane-cytoskeletal linker Ezrin, as well as attenuation of the paracrine effects of colon carcinoma-secreted factors on fibroblast migration and mitogenesis. As such, km23-1 inhibitors may represent a viable therapeutic strategy for interfering with colon cancer progression and invasion.

Proteogenomic analysis of human colon carcinoma cell lines LIM1215, LIM1899, and LIM2405

As part of the genome-wide and chromosome-centric human proteomic project (C-HPP), we have integrated shotgun proteomics approach and a genome-wide transcriptomic approach (RNA-Seq) of a set of human colon cancer cell lines (LIM1215, LIM1899 and LIM2405) that were selected to represent a wide range of pathological states of colorectal cancer. The combination of a standard proteomics approach (1D-gel electrophoresis coupled to LC/ion trap mass spectrometry) and RNA-Seq allowed us to exploit the greater depth of the transcriptomics measurement (∼ 9800 transcripts per cell line) versus the protein observations (∼ 1900 protein identifications per cell line). Conversely, the proteomics data were helpful in identifying both cancer associated proteins with differential expression patterns as well as protein networks and pathways which appear to be deregulated in these cell lines. Examples of potential markers include mortalin, nucleophosmin, ezrin, LASP1, alpha and beta forms of spectrin, exportin, the carcinoembryonic antigen family, EGFR and MET. Interaction analyses identified the large intermediate filament family, the protein folding network and adapter proteins in focal adhesion networks, which included the CDC42 and RHOA signaling pathways that may have potential for identifying phenotypic states representing poorly and moderately differentiated states of CRC, with or without metastases.

Ezrin expression in rectal cancer predicts time to development of local recurrence

PURPOSE

Improved outcome after rectal cancer surgery requires identification of novel risk factors of tumour recurrence in order to personalise therapy, that is, enhanced selection of high-risk patients to additional radiochemotherapy or intensified follow-up. In several tumour types, including colorectal cancer, high expression of the membrane-cytoskeleton linker ezrin has been suggested to impair prognosis but has not yet reached clinical application. We evaluated the expression of ezrin in rectal cancer with a focus on the identification of a marker for local tumour recurrence.

METHODS

Immunohistochemical expression of ezrin was analysed in 104 primary rectal cancers from patients who developed local recurrences despite being treated with R0 major abdominal surgery. Time to local recurrence and distant metastasis as well as 5-year overall and cancer-specific survival were used as end points.

RESULTS

Ezrin expression was weak in 17% of the tumours, moderate in 62%, and intense in 21%. The time to local recurrence was significantly shorter (p = 0.0004) for patients with tumours showing high ezrin expression. No correlation between ezrin expression and time to distant metastasis was identified. Survival data were similar between groups irrespective of ezrin expression in the primary tumours.

CONCLUSIONS

Our findings suggest that increased expression of ezrin may represent a marker of aggressive biological behaviour in rectal cancer. Although further validation is needed, ezrin may represent a relevant marker for personalised treatment of rectal cancer with respect to risk of local recurrence after R0 surgery.

Decreased ezrin and paxillin expression in human urothelial bladder tumors correlate with tumor progression

OBJECTIVES

F-actin binding proteins ezrin and paxillin are involved in cell adhesion and cell migration/invasion. The aim of the study was to investigate their role in urothelial bladder carcinogenesis.

MATERIALS AND METHODS

Expression of ezrin and paxillin was studied by immunohistochemistry in 104 and 96 cases of urothelial bladder tumors, respectively. Correlations with clinicopathologic data and expression of p53, E-cadherin, and β-catenin were examined.

RESULTS

Positive ezrin and paxillin protein expression was found in 99% and 93.7% of cases, respectively. Membranous expression of ezrin was significantly lower in high grade tumors and correlated with invasion. Multivariate analysis showed that ezrin is an independent predictor of muscularis propria invasion. Paxillin expression was significantly decreased in urothelial carcinomas compared with tumors of low malignant potential and low paxillin levels also correlated with advancing tumor stage and invasion. A statistically significant correlation was found between membranous ezrin and E-cadherin as well as between ezrin and paxillin expression in urothelial tumors.

CONCLUSIONS

Down-regulation of ezrin and paxillin in urothelial bladder tumors is associated with aggressive tumor features and invasiveness.

Immunohistochemical expression of ezrin in cutaneous basal and squamous cell carcinomas

Ezrin is a member of the ezrin-radixin-moesin family of proteins, which link the actin-containing cytoskeleton to the plasma membrane. Overexpression of ezrin protein is correlated with the metastatic potential in several cancers. Little is known about the distribution of ezrin in normal epidermis and nonmelanoma skin cancer; therefore, in the current study, we examined the immunohistochemical expression of ezrin in normal skin (10 biopsies) and epithelial skin tumors (25 basal cell carcinoma [BCC] and 20 squamous cell carcinoma [SCC]). Ezrin was expressed in epidermis of all normal controls with a prominent membranous pattern compared with 93.3% positivity in malignant cases with a significant higher intensity (assessed by H score) in favor of the latter (P = .002). Cytoplasmic expression of ezrin either alone or associated with membranous expression was both seen in BCC and SCC. The median value of H score in SCC (160) cases was higher than that in BCC (60). H score values of ezrin expression in BCC was significantly higher in tumors arising in sites other than the head and neck (P = .04). In SCC, the intensity of ezrin expression tended to be associated with advanced stage (P = .08). Our study demonstrated the probable tumorigenic role of ezrin in epithelial skin tumor formation. It may enhance local invasion or metastasis of epithelial skin tumors, which necessitates further larger study to clarify. The intensity rather than the pattern of ezrin expression had a more probable impact on the tumor behavior.

Potential transcriptional regulatory regions exist upstream of the human ezrin gene promoter in esophageal carcinoma cells

We previously demonstrated that the region -87/+134 of the human ezrin gene (VIL2) exhibited promoter activity in human esophageal carcinoma EC109 cells, and a further upstream region -1324/-890 positively regulated transcription. In this study, to identify the transcriptional regulatory regions upstream of the VIL2 promoter, we cloned VIL2 -1541/-706 segment containing the -1324/-890, and investigated its transcriptional regulatory properties via luciferase assays in transiently transfected cells. In EC109 cells, it was found that VIL2 -1541/-706 possessed promoter and enhancer activities. We also localized transcriptional regulatory regions by fusing 5'- or 3'-deletion segments of VIL2 -1541/-706 to a luciferase reporter. We found that there were three positive and one negative transcriptional regulatory regions within VIL2 -1541/-706 in EC109 cells. When these regions were separately located upstream of the luciferase gene without promoter, or located upstream of the VIL2 promoter or SV40 promoter directing the luciferase gene, only VIL2 -1297/-1186 exhibited considerable promoter and enhancer activities, which were lower than those of -1541/-706. In addition, transient expression of Sp1 increased ezrin expression and the transcriptional activation of VIL2 -1297/-1186. Other three regions, although exhibiting significantly positive or negative transcriptional regulation in deletion experiments, showed a weaker or absent regulation. These data suggested that more than one region upstream of the VIL2 promoter participated in VIL2 transcription, and the VIL2 -1297/-1186, probably as a key transcriptional regulatory region, regulated VIL2 transcription in company with other potential regulatory regions.

Proteomic identification of the differentially expressed proteins in human lung epithelial cells by airborne particulate matter

Exposure to airborne PM₁₀, particulate matter with a median aerodynamic diameter of less than 10 µm, is known to be associated with a number of adverse health effects. To gain a better understanding of the cytotoxic mechanism and to develop protein biomarker candidates for PM₁₀-induced toxicity, proteomic analyses were performed in human lung epithelial cells. Two-dimensional gel electrophoresis (2-DE) was followed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to analyze the proteins differentially expressed by exposure to PM₁₀. Analysis of 2-DE gels revealed more than 1270 protein spots in the cells, of which 36 showed changes of more than 2-fold on exposure to PM₁₀ (up-regulation, n = 6; down-regulation, n = 30). The glycolytic enzyme pyruvate kinase, which also plays a role in tumor metabolism, showed a marked increase in expression, whereas the cytoskeleton-related vinculin and anti-inflammatory annexin 1 showed marked decreases in expression.

Ezrin expression as a prognostic marker in colorectal adenocarcinoma

Ezrin protein acts in the regulation of cytoskeletal and directly influences survival and tumor progression; there is an increase in its expression in metastatic cells and tissues in several types of cancer including colorectal cancer. 250 Patients with colorectal cancer submitted to surgery from 1995 to 2002. Protein expression was carried through by Tissue Micro Array immunohistochemical tests of paraffined neoplasic tissues and associated with clinical variables. Differentiation degree, lymph node invasion, metastasis at diagnosis, and palliative surgery were associated to a higher expression of the protein and survival. Higher expression of the Ezrin correlates with tumor aggressiveness and worse prognosis for colorectal cancer.

Proteomic profile regulated by the anticancer peptide CIGB-300 in non-small cell lung cancer (NSCLC) cells

CIGB-300 is a proapoptotic peptide-based drug that abrogates the CK2-mediated phosphorylation. This peptide has antineoplastic effect on lung cancer cells in vitro and in vivo. To understand the mechanisms involved on such anticancer activity, the NCI-H125 cell line proteomic profile after short-term incubation (45 min) with CIGB-300 was investigated. As determined by 2-DE or 2D-LC-MS/MS, 137 proteins changed their abundances more than 2-fold in response to the CIGB-300 treatment. The expression levels of proteins related to ribosome biogenesis, metastasis, cell survival and proliferation, apoptosis, and drug resistance were significantly modulated by the presence of CIGB-300. The protein translation process was the most affected (23% of the identified proteins). From the proteome analysis of the NCI-H125 cell line, novel potentialities for CIGB-300 as anticancer agent were evidenced.

Up-regulation of hnRNP A1, Ezrin, tubulin β-2C and Annexin A1 in sentinel lymph nodes of colorectal cancer

AIM: To investigate the early metastasis-associated proteins in sentinel lymph node micrometastasis (SLNMM) of colorectal cancer (CRC) through comparative proteome.

METHODS: Hydrophobic protein samples were extracted from individual-matched normal lymph nodes (NLN) and SLNMM of CRC. Differentially expressed protein spots were detected by two-dimensional electrophoresis and image analysis, and subsequently identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry-mass spectrometry and Western blotting, respectively.

RESULTS: Forty proteins were differentially expressed in NLN and SLNMM, and 4 metastasis-concerned proteins highly expressed in SLNMM were identified to be hnRNP A1, Ezrin, tubulin β-2C and Annexin A1. Further immunohistochemistry staining of these four proteins showed their clinicopathological characteristics in lymph node metastasis of CRC.

CONCLUSION: Variations of hydrophobic protein expression in NLN and SLNMM of CRC and increased expression of hnRNP A1, Ezrin, tubulin β-2C and Annexin A1 in SLNMM suggest a significantly elevated early CRC metastasis.

Enumerating the gene sets in breast cancer, a "direct" alternative to hierarchical clustering

Background

Two-way hierarchical clustering, with results visualized as heatmaps, has served as the method of choice for exploring structure in large matrices of expression data since the advent of microarrays. While it has delivered important insights, including a typology of breast cancer subtypes, it suffers from instability in the face of gene or sample selection, and an inability to detect small sets that may be dominated by larger sets such as the estrogen-related genes in breast cancer. The rank-based partitioning algorithm introduced in this paper addresses several of these limitations. It delivers results comparable to two-way hierarchical clustering, and much more. Applied systematically across a range of parameter settings, it enumerates all the partition-inducing gene sets in a matrix of expression values.

Results

Applied to four large breast cancer datasets, this alternative exploratory method detects more than thirty sets of co-regulated genes, many of which are conserved across experiments and across platforms. Many of these sets are readily identified in biological terms, e.g., "estrogen", "erbb2", and 8p11-12, and several are clinically significant as prognostic of either increased survival ("adipose", "stromal"...) or diminished survival ("proliferation", "immune/interferon", "histone",...). Of special interest are the sets that effectively factor "immune response" and "stromal signalling".

Conclusion

The gene sets induced by the enumeration include many of the sets reported in the literature. In this regard these inventories confirm and consolidate findings from microarray-based work on breast cancer over the last decade. But, the enumerations also identify gene sets that have not been studied as of yet, some of which are prognostic of survival. The sets induced are robust, biologically meaningful, and serve to reveal a finer structure in existing breast cancer microarrays.

Nuclear factor-kappaB signaling and ezrin are essential for L1-mediated metastasis of colon cancer cells

Hyperactivation of beta-catenin-T-cell-factor (TCF)-regulated gene transcription is a hallmark of colorectal cancer (CRC). The cell-neural adhesion molecule L1CAM (hereafter referred to as L1) is a target of beta-catenin-TCF, exclusively expressed at the CRC invasive front in humans. L1 overexpression in CRC cells increases cell growth and motility, and promotes liver metastasis. Genes induced by L1 are also expressed in human CRC tissue but the mechanisms by which L1 confers metastasis are still unknown. We found that signaling by the nuclear factor kappaB (NF-kappaB) is essential, because inhibition of signaling by the inhibitor of kappaB super repressor (IkappaB-SR) blocked L1-mediated metastasis. Overexpression of the NF-kappaB p65 subunit was sufficient to increase CRC cell proliferation, motility and metastasis. Binding of the L1 cytodomain to ezrin - a cytoskeleton-crosslinking protein - is necessary for metastasis because when binding to L1 was interrupted or ezrin gene expression was suppressed with specific shRNA, metastasis did not occur. L1 and ezrin bound to and mediated the phosphorylation of IkappaB. We also observed a complex containing IkappaB, L1 and ezrin in the juxtamembrane region of CRC cells. Furthermore, we found that L1, ezrin and phosphorylated p65 are co-expressed at the invasive front in human CRC tissue, indicating that L1-mediated activation of NF-kappaB signaling involving ezrin is a major route of CRC progression.