Ovarian epithelial carcinoma tyrosine phosphorylation, cell proliferation, and ezrin translocation are stimulated by interleukin 1alpha and epidermal growth factor

Serum anti-CFL1, anti-EZR, and anti-CYPA autoantibody as diagnostic markers in ovarian cancer

The purpose of this study was to identify novel autoantibodies against tumor-associated antigens (TAAs) and explore a diagnostic panel for Ovarian cancer (OC). Enzyme-linked immunosorbent assay was used to detect the expression of five anti-TAA autoantibodies in the discovery (70 OC and 70 normal controls) and validation cohorts (128 OC and 128 normal controls). Machine learning methods were used to construct a diagnostic panel. Serum samples from 81 patients with benign ovarian disease were used to identify the specificity of anti-TAA autoantibodies for OC. In both the discovery and validation cohorts, the expression of anti-CFL1, anti-EZR, anti-CYPA, and anti-PFN1 was higher in patients with OC than that in normal controls. The area under the receiver operating characteristic curve, sensitivity, and specificity of the panel containing anti-CFL1, anti-EZR, and anti-CYPA were 0.762, 55.56%, and 81.31%. The panel identified 53.06%, 53.33%, and 51.11% of CA125 negative, HE4 negative and the Risk of Ovarian Malignancy Algorithm negative OC patients, respectively. The combination of the three anti-TAA autoantibodies can serve as a favorable diagnostic tool for OC and has the potential to be a complementary biomarker for CA125 and HE4 in the diagnosis of ovarian cancer.

Immunohistochemical markers for equine granulosa cell tumors: a pilot study

Sex cord-stromal tumors (SCSTs), generally referred to as granulosa cell tumors (GCTs) or granulosa-theca cell tumors (GTCTs) in equids, show complex compositions and variable numbers of hormone-producing cells. These tumors can be difficult to diagnose, especially in early stages. Therefore, we tested a panel of antibodies for vimentin, smooth muscle actin, laminin, Ki-67, E-cadherin, calretinin, moesin, p-ezrin, AMH, and aromatase, markers used for tumor composition and classification, progression, and prognosis in human SCSTs, on an exemplary grapefruit-size equine GCT within the left ovary of a 13-year-old mare with stallion-like behavior and elevated testosterone levels in comparison with normal ovarian tissue. The tumor showed a low proliferation rate and prominent moesin and p-ezrin staining in granulosa cells. E-cadherin, calretinin, aromatase, and AMH are suggested to be potential markers for different cell components of equine SCSTs that can support tumor diagnosis and classification.

Ezrin immunoexpression in gastric cells of domestic cats infected with Helicobacter spp

The aim of this study was to evaluate de immunoexpression of ezrin in gastric cells of domestic cats infected with Helicobacter spp. and with chronic gastritis. Twenty paraffin-embedded gastric samples were selected based on previous positive results for Helicobacter spp. in the Rapid Urease Test, Warthin-Starry staining and cytology. Haematoxylin-eosin stained sections was done to evaluate inflammatory cell infiltrates. Immunohistochemical analysis was done using anti-Helicobacter pylori and anti-Ezrin antibodies. The analysis of inflammatory infiltrates revealed 8/20 (40%) in score 0, 11/20 (55%) in score 1 and 1/20 (5%) in score 2. The labelling observed in the immunohistochemical analysis using anti-Helicobacter spp. antibody showed no samples with score 0; 4/20 (20%) with score 1; 7/20 35% with score 2 and 9/20 (45%) with score 3. Ezrin overexpression on the cytoplasm of parietal cells was revealed in 18 out of 20 samples (90%). Of these, 10 cases (45%) achieved the score 1; 6 cases (30%) the score 2 and 2 cases (10%) the score 3. On the surface and pit cells there was an increase in Ezrin immnoexpression in 12 out of the 20 samples (60%), of which 8 samples (40%) achieved the score 1 and 4 samples (20%) the score 2. No sample were classified in score 3. Statistically significant differences (p = 0.026) were observed between the inflammatory infiltrate in the gastric mucosa and the immunoexpression of Ezrin in the cytoplasm of parietal cells. It was concluded that ezrin had an increased immunoexpression in the gastric mucosa of cats with chronic gastritis.

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.

Ezrin Contributes to the Plasma Membrane Expression of PD-L1 in A2780 Cells

Programmed death ligand–1 (PD–L1) is one of the immune checkpoint molecule localized on the plasma membrane of numerous cancer cells that negatively regulates T-cell-mediated immunosurveillance. Despite the remarkable efficacy and safety profile of immune checkpoint inhibitors (ICIs), such as anti-PD–L1 antibodies, restricted poor therapeutic responses to ICIs are often observed in patients with ovarian cancer. Because higher expression of PD–L1 in advanced ovarian cancer is associated with a decreased survival rate, identifying the potential molecules to regulate the plasma membrane expression of PD–L1 may provide a novel therapeutic strategy to improve the efficacy of ICIs against ovarian cancers. Here, we reveal the involvement of the ezrin/radixin/moesin (ERM) family, which crosslinks transmembrane proteins with the actin cytoskeleton by serving as a scaffold protein, in the plasma membrane expression of PD–L1 in the human epithelial ovarian cancer cell line A2780. Our results demonstrate that PD–L1 and all three ERMs were expressed at the mRNA and protein levels in A2780 cells, and that PD–L1 was highly colocalized with ezrin and moesin, but moderately with radixin, in the plasma membrane. Interestingly, RNA interference-mediated gene silencing of ezrin, but not of radixin or moesin, substantially reduced the plasma membrane expression of PD–L1 without altering its mRNA expression. In conclusion, our results indicate that ezrin may be responsible for the plasma membrane expression of PD–L1, possibly by serving as a scaffold protein in A2780 cells. Ezrin is a potential therapeutic target for improving the efficacy of ICIs against ovarian cancers.

Ectopic Endometrial Cell-Derived Exosomal Moesin Induces Eutopic Endometrial Cell Migration, Enhances Angiogenesis and Cytosolic Inflammation in Lesions Contributes to Endometriosis Progression

Background: Endometriosis (EMs) is the most common gynaecological disorder with its etiology and/or pathophysiology remains enigmatic. Recent studies showed that extracellular vesicles (EVs), exosomes in particular, play a critical role in developing various clinical disorders. However, the implication of exosomes in endometriosis progression has not been well elucidated.

Method: The ectopic stromal cellular exosomes (eEVs) were assessed by transwell assay, scratch tests, tube formation assay, western blot, and qRT-PCR analysis. Protein expression profiles of exosomes in endometrial tissue and vaginal discharge collected from patients with EMS and healthy donors were analysed by Mass spectrometry. siRNA interference technology was used to inhibit the expression of exosomal protein for the functional analysis in in-vivo. Finally, in-vitro experiments were performed to validate the results that we observed in EMs mouse model.

Results:In vitro, we discovered that eEVs improved NSC migratory potential by upregulating MMP9 expression and activity. eEVs also aided angiogenesis and elevated the expression of inflammatory cytokines in ovarian epithelial cells, according to our findings. Moesin (MSN) levels in ESC exosomes were substantially greater than in NSC exosomes (1.22e⁸±5.58e⁶ vs. 6.605e⁷±4.574e⁶, LFQ intensity), as shown by protein mass spectrometry and bioinformatics analysis. In ectopic stromal cells, ERa receptors stimulated the RhoA/Rock-2/MSN pathway. We discovered that downregulating exosomal moesin reduced NSC migration (about 3-fold change) and MMP9 expression (about 2-fold change). On the other hand, Exomsni inhibited angiogenesis and inflammatory cytokine release. In vivo the result of immunohistochemistry and immunofluorescence demonstrated that exosomal MSN substantially modified the expression of MM9, VEGFR and p-VEGFR in polyclonal lesions. In addition, we discovered an elevation in the expression of proinflammatory factors in the surrounding tissue.

Conclusion: Exosomal MSN derived from ectopic stromal cells can contribute to endometriosis progression by mediating the construction of a “migration-vascularization-inflammation” loop in the ectopic environment.

Unexpected therapeutic effects of cisplatin

Cisplatin is a widely used chemotherapeutic agent that is clinically approved to fight both carcinomas and sarcomas. It has relatively high efficiency in treating ovarian cancers and metastatic testicular cancers. It is generally accepted that the major mechanism of cisplatin anti-cancer action is DNA damage. However, cisplatin is also effective in metastatic cancers and should, therefore, affect slow-cycling cancer stem cells in some way. In this review, we focused on the alternative effects of cisplatin that can support a good therapeutic response. First, attention was paid to the effects of cisplatin at the cellular level such as changes in intracellular pH and cellular mechanical properties. Alternative cellular targets of cisplatin, and the effects of cisplatin on cancer cell metabolism and ER stress were also discussed. Furthermore, the impacts of cisplatin on the tumor microenvironment and in the whole organism context were reviewed. In this review, we try to reveal possible causes of the unexpected effectiveness of this anti-cancer drug.

Low-dose epirubicin inhibits ezrin-mediated metastatic behavior of breast cancer cells

Aims and background

Overexpression of ezrin contributes to the progression and invasiveness of several human cancers; however, its role in breast cancer metastasis has not been investigated in detail.

Methods

Ezrin expression in tissue samples from patients with invasive ductal carcinoma of the breast was detected by immunohistochemistry. Ezrin expression in a breast cancer cell line was evaluated using Western blot and RT-PCR.

Results

Elevated expression of ezrin was associated with lymph node metastasis and poor prognosis in patients with invasive ductal carcinoma. Ezrin expression was related to the invasiveness of breast cancer cells in vitro. Low-dose epirubicin inhibited the migration of breast cancer cells in a concentration-dependent manner without promoting cytotoxicity in vitro and decreased the expression of ezrin in a concentration-dependent manner.

Conclusions

Low-dose epirubicin may be antimetastatic without promoting cytotoxic effects and could serve as a target for the development of therapeutics for breast carcinoma.

LH and FSH promote migration and invasion properties of a breast cancer cell line through regulatory actions on the actin cytoskeleton

Reproductive hormones influence breast cancer development and progression. While the actions of sex steroids in this setting are established, tentative evidence suggests that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) may also play a role, yet this remains elusive. We here identify that T-47D breast cancer cells express functional receptors for FSH and LH, and that these hormones regulate breast cancer cell motility and invasion through the control of the actin cytoskeleton and the formation of cortical actin aggregates and focal adhesion complexes. Such actions are mediated by the cytoskeletal controllers Moesin and focal adhesion kinase (FAK). Moesin is recruited rapidly by FSH and LH through a signaling cascade requiring the G protein Gα₁₃ and the Rho-associated kinase, ROCK-2. FSH and LH activate FAK via a Gα_i/β and c-Src-dependent signaling cascade. Both cascades involve signaling to phosphatidylinositol-3 kinase and Akt. FSH and LH receptors and the related signaling intermediates are necessary for the actions of gonadotrophins on breast cancer cell cytoskeletal rearrangement, migration and invasion. These findings provide original information on the actions of gonadotrophins on breast cancer cells and may have clinical implications for the use of drugs that modulate gonadotrophins in breast cancer patients.

Expression of Ezrin and Estrogen Receptors During Cervical Carcinogenesis

RATIONALE

Development of cervical squamous carcinoma (CXCA) is accompanied by changes in estrogen receptors (ERs, ERα and ERβ) and ezrin expression; however, reports have been conflicting. Using histologically documented staging of cervical biopsies, we determined ezrin and ER relationships during CXCA development.

METHODS

Immunoreactive (ir) ezrin, ir-ERα, and ir-ERβ were studied in normal epithelium, carcinoma in situ/cervical intraepithelial neoplasia (CIN) 1 to 3, and local invasion or metastatic CXCA. Results were compared using H scoring. Cultures of Caski metastatic CXCA cells were treated with estradiol and/or tamoxifen and studied for ER-driven ir-ezrin and the morphologic response.

RESULTS

Koilocytosis was present and indicated viral presence. The ezrin H score increased from CIN1 to CIN3, reaching significant differences from normal by CIN3 ( P = .004) and 2× normal in metastatic CXCA. Estrogen receptor α and ERβ H scores fell, reaching significance by CIN3 (ERα, P = .0001; ERβ, P = .024). During estradiol treatment, ezrin in Caski cells increased and localized to the periphery, in ruffles and processes. The selective ER modulator tamoxifen blocked the estradiol-induced changes.

CONCLUSIONS

During cervical carcinogenesis, the usual relationship between estrogen and ezrin induction is abridged. This is consistent with the effects of human papilloma virus viral proteins such as E6 and E7 that upregulate SIX1, a protein that induces ezrin. Cervical carcinogenesis is progressive but arrests at the preinvasive stage for varying lengths of time. These studies suggest that changes in ezrin may be associated with the development of the invasive phenotype and penetration of the basement membrane. They also raise the possibility that inhibiting ezrin expression could be a target for the prevention of invasive CXCA.

Ezrin Is Associated with Disease Progression in Ovarian Carcinoma

Objective

Ezrin and p130Cas are structural proteins with an important role in signaling pathways and have been shown to promote cancer dissemination. We previously reported on overexpression of both ezrin and p130Cas in breast carcinoma effusions compared to primary carcinomas. Since ovarian and breast carcinomas share the ability to disseminate by forming malignant effusions, we sought to study the role of these molecules in ovarian carcinoma (OC).

Methods

OC cell lines were cultured in two different 3-dimensional conditions, on alginate scaffolds and as spheroids, which served as models for solid tumor and malignant effusions, respectively. shRNA was used to reduce protein expression in the cells. The malignant potential was evaluated by chemo-invasion assay, branching capacity on Matrigel and rate of proliferation. Subsequently, clinical specimens of high-grade serous carcinoma effusions, ovarian tumors and solid metastases were analyzed for ezrin and p130Cas expression.

Results

Higher ezrin expression was found in cells composing the spheroids compared to their counterparts cultured on alginate scaffold and in clinical samples of malignant effusions compared to solid tumors. In addition, reduced Ezrin expression impaired the invasion ability and the branching capacity of OC cells to a greater extent than reduced p130Cas expression. However, ezrin and p130Cas expression in effusions was unrelated to clinical outcome.

Conclusions

The 3-dimensional cell cultures were found to mimic the different tumor sites and be applicable as a model. The in vitro results concur with the clinical specimen analysis, suggesting that in OC, the role of ezrin in disease progression is more pronounced than that of p130Cas.

Prognostic Value of Ezrin in Various Cancers: A Systematic Review and Updated Meta-analysis

More and more studies have investigated the effects of Ezrin expression level on the prognostic role in various tumors. However, the results remain controversial rather than conclusive. Here, we performed a systematic review and meta-analysis to evaluate the correlation of Ezrin expression with the prognosis in various tumors. the pooled hazard ratios (HR) with the corresponding 95% confidence intervals (95% CI) were calculated to evaluate the degree of the association. The overall results of fifty-five studies with 6675 patients showed that elevated Ezrin expression was associated with a worse prognosis in patients with cancers, with the pooled HRs of 1.86 (95% CI: 1.51–2.31, P < 0.001) for over survival (OS), 2.55 (95% CI: 2.14–3.05, P < 0.001) for disease-specific survival (DFS) and 2.02 (95% CI: 1.13–3.63, P = 0.018) for disease-specific survival (DSS)/metastasis-free survival (MFS) by the random, fixed and random effect model respectively. Similar results were also observed in the stratified analyses by tumor types, ethnicity background and sample source. This meta-analysis suggests that Ezrin may be a potential prognostic marker in cancer patients. High Ezrin is associated with a poor prognosis in a variety of solid tumors.

Plasmodium vivax inhibits erythroid cell growth through altered phosphorylation of the cytoskeletal protein ezrin

BACKGROUND

The underlying causes of severe malarial anaemia are multifactorial. In previously reports, Plasmodium vivax was found to be able to directly inhibited erythroid cell proliferation and differentiation. The molecular mechanisms underlying the suppression of erythropoiesis by P. vivax are remarkably complex and remain unclear. In this study, a phosphoproteomic approach was performed to dissect the molecular mechanism of phosphoprotein regulation, which is involved in the inhibitory effect of parasites on erythroid cell development.

METHODS

This study describes the first comparative phosphoproteome analysis of growing erythroid cells (gECs), derived from human haematopoietic stem cells, exposed to lysates of infected erythrocytes (IE)/uninfected erythrocytes (UE) for 24, 48 and 72 h. This study utilized IMAC phosphoprotein isolation directly coupled with LC MS/MS analysis.

RESULTS

Lysed IE significantly inhibited gEC growth at 48 and 72 h and cell division resulting in the accumulation of cells in G0 phase. The relative levels of forty four phosphoproteins were determined from gECs exposed to IE/UE for 24-72 h and compared with the media control using the label-free quantitation technique. Interestingly, the levels of three phosphoproteins: ezrin, alpha actinin-1, and Rho kinase were significantly (p < 0.05) altered. These proteins display interactions and are involved in the regulation of the cellular cytoskeleton. Particularly affected was ezrin (phosphorylated at Thr567), which is normally localized to gEC cell extension peripheral processes. Following exposure to IE, for 48-72 h, the ezrin signal intensity was weak or absent. This result suggests that phospho-ezrin is important for actin cytoskeleton regulation during erythroid cell growth and division.

CONCLUSIONS

These findings suggest that parasite proteins are able to inhibit erythroid cell growth by down-regulation of ezrin phosphorylation, leading to ineffective erythropoiesis ultimately resulting in severe malarial anaemia. A better understanding of the mechanisms of ineffective erythropoiesis may be beneficial in the development of therapeutic strategies to prevent severe malarial anaemia.

Amphiregulin induces human ovarian cancer cell invasion by down-regulating E-cadherin expression

Aberrant epidermal growth factor receptor (EGFR) activation is associated with ovarian cancer progression. In this study, we report that the EGFR ligand amphiregulin (AREG) stimulates cell invasion and down-regulates E-cadherin expression in two human ovarian cancer cell lines, SKOV3 and OVCAR5. In addition, AREG increases the expression of transcriptional repressors of E-cadherin including SNAIL, SLUG and ZEB1. siRNA targeting SNAIL or SLUG abolishes AREG-induced cell invasion. Moreover, ERK1/2 and AKT pathways are involved in AREG-induced E-cadherin down-regulation and cell invasion. Finally, we show that three EGFR ligands, AREG, epidermal growth factor (EGF) and transforming growth factor-α (TGF-α), exhibit comparable effects in down-regulating E-cadherin and promoting cell invasion. This study demonstrates that AREG induces ovarian cancer cell invasion by down-regulating E-cadherin expression.

Addition of vandetanib to pegylated liposomal doxorubicin (PLD) in patients with recurrent ovarian cancer. A randomized phase I/II study of the AGO Study Group (AGO-OVAR 2.13)

BACKGROUND

PLD is a standard treatment in patients with recurrent platinum-resistant or refractory ovarian cancer. Vandetanib is an oral once daily administered inhibitor of VEGFR-, EGFR- and RET-signaling with activity in combination with chemotherapy in some solid tumours. We aimed to establish a feasible combination therapy of PLD and vandetanib in ovarian cancer.

METHODS

Eligible patients were treated with PLD 50 mg/m(2) q28 and vandetanib 100 mg/d po. It was planned to recruit at least 10 patients evaluable for toxicity over 2 treatment cycles. Primary endpoints were tolerability and safety; secondary endpoint was efficacy.

RESULTS

Fourteen of 15 registered patients started treatment and were evaluable for toxicity. Three patients (21%) stopped after first cycle (PD, withdrawal of consent, nausea/vomiting). The remaining 11 patients were treated for at least 2 cycles. Dose reductions of PLD and vandetanib were indicated in 4 (29%) and 5 patients (36%), respectively. The following G3/4 toxicities occurred per patient: 2 (14%) elevated liver enzymes G3, 2 (14%) neutropenia G3/4, 5 (36%) PPE G3/4, 2 (14%) mucositis G3. Tyrosine kinase inhibitor attributed side effects like hypertension or bowel perforations were not reported. Toxicity led to cessation of treatment in 4 patients (29%). Ten patients were evaluable for response: PR 1, SD 4. The median PFS was 6.7 months and median OS was 11.1 months.

CONCLUSIONS

The combination of PLD 50 mg/m(2)q28 and vandetanib 100 mg/d is feasible, but may be intolerable due to reported toxicity.

Autoantibody biomarkers identified by proteomics methods distinguish ovarian cancer from non-ovarian cancer with various CA-125 levels

PURPOSE

CA-125 has been a valuable marker for detecting ovarian cancer, however, it is not sensitive enough to detect early-stage disease and not specific to ovarian cancer. The purpose of our study was to identify autoantibody markers that are specific to ovarian cancer regardless of CA-125 levels.

METHODS

Top-down and iTRAQ quantitative proteomics methods were used to identify high-frequency autoantibodies in ovarian cancer. Protein microarrays comprising the recombinant autoantigens were screened using serum samples from various stages of ovarian cancer with diverse levels of CA-125 as well as benign and healthy controls. ROC curve and dot blot analyses were performed to validate the sensitivity and specificity of the autoantibody markers.

RESULTS

The proteomics methodologies identified more than 60 potential high-frequency autoantibodies in ovarian cancer. Individual serum samples from ovarian cancer stages I-IV compared to control samples that were screened on a microarray containing native recombinant autoantigens revealed a panel of stage I high-frequency autoantibodies. Preliminary ROC curve and dot blot analyses performed with the ovarian cancer samples showed higher specificity and sensitivity as compared to CA-125. Three autoantibody markers exhibited higher specificity in various stages of ovarian cancer with low and normal CA-125 levels.

CONCLUSIONS

Proteomics technologies are suitable for the identification of protein biomarkers and also the identification of autoantibody biomarkers when combined with protein microarray screening. Using native recombinant autoantigen arrays to screen autoantibody markers, it is possible to identify markers with higher sensitivity and specificity than CA-125 that are relevant to early detection of ovarian cancer.

Sphingolipid regulation of ezrin, radixin, and moesin proteins family: implications for cell dynamics

A key but poorly studied domain of sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive sphingolipids. This review describes the current understanding of sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.

Epidermal growth factor-induced cellular invasion requires sphingosine-1-phosphate/sphingosine-1-phosphate 2 receptor-mediated ezrin activation

Ezrin, radixin, and moesin (ERM) proteins link cortical actin to the plasma membrane and coordinate cellular events that require cytoskeletal rearrangement, including cell division, migration, and invasion. While ERM proteins are involved in many important cellular events, the mechanisms regulating their function are not completely understood. Our laboratory previously identified reciprocal roles for the sphingolipids ceramide and sphingosine-1-phosphate (S1P) in the regulation of ERM proteins. We recently showed that ceramide-induced activation of PP1α leads to dephosphorylation and inactivation of ERM proteins, while S1P results in phosphorylation and activation of ERM proteins. Following these findings, we aimed to examine known inducers of the SK/S1P pathway and evaluate their ability to regulate ERM proteins. We examined EGF, a known inducer of the SK/S1P pathway, for its ability to regulate the ERM family of proteins. We found that EGF induces ERM c-terminal threonine phosphorylation via activation of the SK/S1P pathway, as this was prevented by siRNA knockdown or pharmacological inhibition of SK. Using pharmacological, as well as genetic, knockdown approaches, we determined that EGF induces ERM phosphorylation via activation of S1PR2. In addition, EGF led to cell polarization in the form of lamellipodia, and this occurred through a mechanism involving S1PR2-mediated phosphorylation of ezrin T567. EGF-induced cellular invasion was also found to be dependent on S1PR2-induced T567 ezrin phosphorylation, such that S1PR2 antagonist, JTE-013, and expression of a dominant-negative ezrin mutant prevented cellular invasion toward EGF. In this work, a novel mechanism of EGF-stimulated invasion is unveiled, whereby S1P-mediated activation of S1PR2 and phosphorylation of ezrin T567 is required.

Knockdown of Ezrin by RNA interference reverses malignant behavior of human pancreatic cancer cells in vitro

BACKGROUND

Pancreatic cancer is one of the most aggressive tumors with a dismal prognosis. The membrane cytoskeletal crosslinker Ezrin participates in several functions including cell proliferation, adhesion, motility and survival. There is increasing evidence that Ezrin is overexpressed in vast majority of malignant tumors and regulates tumor progression. However, its roles in pancreatic cancer remain elusive.

METHODS

Three pairs of specific Ezrin siRNAs were designed and synthetized and screened to determine the most efficient one for construction of a hairpin RNA plasmid targeting Ezrin. After transfection into the Panc-1 pancreatic cancer cell line, real-time quantitative PCR and Western blotting were performed to examine the expression of mRNA and protein. The MTT method was applied to examine the proliferation and the drug sensibility to Gemcitabine. Flow cytometry was used to assess the cycle and apoptosis, while capacity for invasion was determined with transwell chambers. Furthermore, we detected phosphorylated-Erk1/2 protein and phosphorylated-Akt protein by Western blotting.

RESULTS

Real-time quantitative PCR and Western blotting revealed that Ezrin expression was notably down-regulated at both mRNA and protein levels by RNA interference (P< 0.01). Proliferation was inhibited and drug resistance to gemcitabine was improved (P< 0.05). Flow cytometry showed that the proportion of cells in the G1/G0 phase increased (P< 0.01), and in G2/M and S phases decreased (P< 0.05), with no apparent differences in apoptosis (P> 0.05). The capacity for invasion was markedly reduced (P< 0.01). In addition, down-regulating Ezrin expression had no effect on phosphorylated-Akt protein (P>0.05), but could decrease the level of phosphorylated-Erk1/2 protein (P< 0.05).

CONCLUSIONS

RNA interference of Ezrin could inhibit its expression in the pancreatic cancer cells line Panc-1, leading to a potent suppression of malignant behavior in vitro. Assessment of potential as a target for pancreatic cancer treatment is clearly warranted.

ERM/Rho protein expression in ductal breast cancer: a 15 year follow-up

PURPOSE

The aim of this study was to examine the expression of ERM (ezrin, moesin) and Rho (RhoA, RhoB and Cdc42) proteins in breast cancer (BC) patients and to investigate the relationship between the sub-cellular localisation of these proteins and clinicopathological characteristics and patient survival.

METHODS

The expression and specific sub-cellular distribution of the ERM/Rho proteins was analysed by immunohistochemistry in a homogeneous group of 85 stage II ductal BC patients with a follow-up of 15 years.

RESULTS

Enhanced immunoreactivity of all analysed proteins was found to be associated with the presence of lymph node metastases (ezrin, P = 0.047, moesin, P = 0.038, RhoA, P = 0.024, RhoB, P = 0.004 and Cdc42, P = 0.047). Nuclear localisation of ezrin was found to correlate with the presence of lymph nodes metastases (P = 0.004) and with histological de-differentiation (P = 0.015). In contrast, we found that the nuclear topography of RhoA and Cdc42, and the perinuclear localisation of RhoB, were strongly associated with a lack of nodal metastases (P = 0.008, P = 0.048, P = 0.001, respectively), whereas a decreased reactivity of RhoA in the stromal compartment of BC tumours was associated with the presence of lymph node metastases (P = 0.011). No relationship was observed between ERM/Rho protein expression and oestrogen receptor (ER), progesterone receptor (PgR) or HER-2 reactivity in the BC cells. Also, ERM/Rho protein expression did not predict patient survival, but RhoB over-expression in the stromal compartment of the tumours was found to be associated with a better prognosis (P = 0.0106).

CONCLUSIONS

The ERM/Rho immunoprofile and the assessment of its specific sub-cellular localisation may be instrumental for the prediction of lymph node metastases in ductal BC patients.

Fascin-1, ezrin and paxillin contribute to the malignant progression and are predictors of clinical prognosis in laryngeal squamous cell carcinoma

Aims

Fascin-1, ezrin and paxillin, cytoskeleton-associated proteins, have been implicated in several human cancers, but their role in laryngeal squamous cell carcinoma (LSCC) is unknown. We investigated the association of their expression and clinicopathologic factors and their prognostic value in LSCC.

Materials and Methods

Quantitative RT-PCR and western blot analyses were used to examine mRNA and protein levels in 10 fresh LSCC specimens and 10 corresponding adjacent normal margin (ANM) tissues from patients undergoing surgery in 2012. We used immunohistochemistry to retrospectively study 216 paraffin blocks of LSCC samples from patients (193 men) who had undergone surgery between 2000 and 2006 and had not received special treatment before the diagnosis. Univariate analysis of patient survival involved the Kaplan–Meier method. Multivariate analyses involved the Cox proportional hazards model.

Results

The relative mRNA and protein levels of fascin-1, ezrin and paxillin were significantly greater in LSCC than ANM tissue (P<0.05). The high expression of fascin-1, ezrin or paxillin was positively correlated with poor tumor differentiation, cervical lymph node metastasis (N+), and advanced clinical stage (III+IV) (P<0.05) but not sex or metastasis. In addition, a high expression of fascin-1 (P = 0.007) or ezrin (P = 0.047) was associated with advanced tumor stage (T3+T4). The expression of fascin-1 was higher in smokers than non-smokers (P = 0.019). A high expression of fascin-1, ezrin or paxillin was associated with poor prognosis.

Conclusions

Fascin-1, ezrin and paxillin may be prognostic of poor outcome with LSCC after surgery. Our study may lead to establishing new molecular therapeutic targets and/or prognostic biomarkers in LSCC.

Atypical ezrin localization as a marker of locally advanced breast cancer

Locally advanced breast cancer (LABC) was initially characterized as a large primary tumor (≥5 cm), associated with or without skin or chest-wall involvement, fixed axillary lymph nodes, or disease spread to the ipsilateral internal mammary or supraclavicular nodes. Since 2002, LABC has been reclassified to include smaller stage IIB tumors (2 to <5 cm) with lymph node involvement, or stages IIIA-IIIB (≥5 cm) with or without nodal involvement. Despite the rather common presentation of LABC, it remains a poorly understood and highly variable clinical presentation of breast cancer that is a challenge to treatment. Here, we characterized a panel of breast tumors of known stage, grade, and key clinical-pathological parameters for the expression of the protein ezrin, which is involved in promoting signaling of the PI3K-Akt-mTOR pathway in response to extracellular and tumor micro-environmental signals, and is involved in breast cancer invasion and metastasis. We show that ezrin, which resides primarily in the apical membrane in normal breast epithelium, relocalizes primarily to the cytoplasm in >80 % of traditional (T3) invasive ductal LABC tumors (≥5 cm). Cytoplasmic ezrin is very strongly associated with a single characteristic in breast cancer-large tumor size. In contrast, in large non-malignant fibroadenomas, ezrin staining was similar to that of normal breast epithelium. Small (T1, 1 cm) invasive ductal carcinomas displayed largely apical membrane and perinuclear ezrin localization with weak cytoplasmic staining. Cytoplasmic ezrin localization was also associated with positive lymph node status, but no other clinical-pathological features, including hormone receptor status, histological or nuclear grade of tumor cell. The cytoplasmic relocalization of ezrin may therefore represent a novel marker for large malignant tumor size, reflecting the unique biology of LABC.

Increased phosphorylation of ezrin/radixin/moesin proteins contributes to proliferation of rheumatoid fibroblast-like synoviocytes

OBJECTIVES

Increasing evidence indicates that ezrin/radixin/moesin (ERM) proteins may play a critical role in cell proliferation. This study examined the role of ERM proteins in proliferation of fibroblast-like synoviocytes (FLS) from patients with RA.

METHODS

Synovial tissues (STs) were obtained from 18 RA and 6 OA patients. The expression of ERM and its phosphorylated proteins in cultured FLS and ST was assessed by western blots or IF staining. Small interference RNA (siRNA)-mediated ERM knockdown was used to inhibit phosphorylation of ERM. Proliferation of FLS was measured by bromodeoxyuridine (BrdU) incorporation into cell DNA and by PCNA immunoblotting.

RESULTS

Our study showed that increased phosphorylation of ERM proteins was found in ST and FLS from patients with RA as compared with OA patients and non-arthritis controls. Treatment with TNF-α, IL-1β or PDGF-induced phosphorylation of ERM proteins in dose- and time-dependent manner by RA FLS, but did not affect the expression of total ERM protein. Rho kinase and p38MAPK signal pathways were involved in TNF-α-induced ERM phosphorylation. We further showed that inhibition of ERM phosphorylation by siRNA-mediated ERM knockdown suppressed TNF-α- or IL-1β-induced BrdU incorporation and PCNA expression in RA FLS.

CONCLUSIONS

This study provides the novel evidence that increased phosphorylation of ERM proteins may contribute to proliferation of RA FLS, suggesting that specific inhibition of ERM phosphorylation may be a new therapeutic approach for RA.

Immune response in ovarian cancer: how is the immune system involved in prognosis and therapy: potential for treatment utilization

Ovarian cancer is one of the leading causes of cancer-related death among women. Resistance to the disease occurs in more than 70% of the cases even after treated with chemotherapy agents such as paclitaxel- and platinum-based agents. The immune system is increasingly becoming a target for intense research in order to study the host's immune response against ovarian cancer. T cell populations, including NK T cells and Tregs, and cytokines have been associated with disease outcome, indicating their increasing clinical significance, having been associated with prognosis and as markers of disease progress, respectively. Harnessing the immune system capacity in order to induce antitumor response remains a major challenge. This paper examines the recent developments in our understanding of the mechanisms of development of the immune response in ovarian cancer as well as its prognostic significance and the existing experience in clinical studies.

Expression of interleukin-1 (IL-1) ligands system in the most common endometriosis-associated ovarian cancer subtypes

OBJECTIVES

Endometrioid carcinoma of the ovary is one of the most types of epithelial ovarian cancer associated to endometrioisis. Endometrioid tumors as well as endometriotic implants are characterized by the presence of epithelial cells, stromal cells, or a combination of booth, that resemble the endometrial cells, suggesting a possible endometrial origin of these tumors. Pro-inflammatory cytokines, including interleukin-1 (IL-1) have been reported to be involved in both endometriosis and ovarian carcinogenesis. The major objective of this study was to determine the level expression of IL-1 ligands system (IL-1alpha, IL-1beta and IL-1RA) in the most common subtypes of ovarian cancer cells compared to endometrial cells.

METHODS

We used primary endometrial cells, endometrial cell line RL-952 and different subtypes of epithelial ovarian cancer cell lines including TOV-112D (endometrioid), TOV-21G (clear cell) and OV-90 (serous). Immunofluorescence and real-time PCR analysis were used respectively for detecting IL-1 ligands at the levels of cell-associated protein and mRNA. Soluble IL-1 ligands were analyzed by ELISA.

RESULTS

We demonstrated that IL-1 ligands were expressed by all endometriosis-associated ovarian cancer subtypes and endometrial cells. In contrast to other cancer ovarian cells, endometrioid cells exhibit a specific decrease of cell-associated IL-1RA expression and its soluble secretion.

CONCLUSION

Endometrioid ovarian cancer exhibits an alteration in the expression of IL-1RA, a key protector against tumorogenic effects of IL-1. This alteration evokes the same alteration observed in endometriotic cells in previous studies. This suggests a possible link between the endometrium, the tissue ectopic endometriosis and endometrioid ovarian cancer.

The Janus-faced role of ezrin in "linking" cells to either normal or metastatic phenotype

In the majority of eukaryotic cells, the ezrin, radixin and moesin (ERM) proteins are involved in many physiologic functions including regulation of actin cytoskeleton, control of cell shape, adhesion, motility and modulation of signal transduction pathways. In a previous study, we used a dominant negative ezrin-mutant to address ezrin involvement in remodeling of actin cytoskeleton and subsequently we depicted ezrin key role in melanoma cell migration and progression. Herein, we highlight recent advances on ezrin involvement in the metastatic phenomenon, including also some more neglected ezrin-related functions. Novel molecular processes driven by ezrin activation include: phagocytosis, acquisition of resistance to chemotherapeutics and triggering of programmed cell death signals. Recent data support an integrated role of ezrin also in development of tumor malignancy. On one hand, ezrin may be responsible of deranged execution of specific known functions such as adhesion and motility and on the other, it may also participate to unique metastatic determinants, through the establishment of aberrant linkages with tumor-related proteins. For instance, ezrin misslocalization, absence or deranged activity has started to be correlated with tumor progression in many tumors of different species, including humans. Concomitantly, ezrin may act simultaneously as a regulatory or deregulatory chaperon in both normal and tumor cells. It is still to be established whether this Janus-faced feature of ezrin is due to some unknown transforming Zelig-like property or to the fact that a tumor-associated molecule preferentially links to ezrin thus distracting it from its normal connections. However, the contribution of ezrin functional deregulation to the acquisition of the metastatic phenotype appears clear and ezrin or ezrin aberrant associations may represent good candidates for future anti-tumor therapies.

RNAi-mediated silencing of ezrin gene reverses malignant behavior of human gastric cancer cell line SGC-7901

OBJECTIVE

To investigate the effects of ezrin targeting gene of RNA interference (RNAi) on human gastric cancer cell line SGC-7901 in vitro.

METHODS

The highly metastatic human gastric cancer cell line SGC-7901 transfected with a small interfering (siRNA) lentivirus vector was selected for this research study. Expressions of ezrin mRNA and ezrin protein in the SGC-7901 cells were detected using RT-PCR and Western blot. Cell apoptosis was observed using flow cytometry. Transwell invasion and the cell adhesion test were used to verify the effect of RNAi on ezrin expression in the human gastric cancer cell line SGC-7901 in vitro.

RESULTS

Ezrin gene targeting via a RNAi-mediated lentivirus vector had obvious inhibitory effects on ezrin expression in the human gastric cancer cell line SGC-7901. The results of the RT-PCR show the obvious inhibition of ezrin mRNA expression in Eai and Ebi groups (0.22 +/- 0.01 vs 0.95 +/- 0.04, P < 0.05; 0.31 +/- 0.01 vs. 0.95 +/- 0.04, P < 0.05). Western blot analysis revealed a 72.35 +/- 3.74% reduction of the ezrin protein level after interference with the ezrin targeting gene. Moreover, the inhibition of ezrin expression clearly inhibited SGC-7901 cell migration and invasion, and improved cell adhesion as well as increased sensitivity to camptothecin-induced apoptosis.

CONCLUSION

Ezrin gene targeting by RNAi can inhibit the metastatic growth and migration of SGC-7901 human gastric cancer cells.

Comparative proteomic study of two closely related ovarian endometrioid adenocarcinoma cell lines using cIEF fractionation and pathway analysis

The proteomic profiles from two distinct ovarian endometrioid tumor-derived cell lines, (MDAH-2774 and TOV-112D) each with different morphological characteristics and genetic mutations, have been studied. Characterization of the differential global protein expression between these two cell lines has important implications for the understanding of the pathogenesis of ovarian endometrioid carcinoma. In this comparative proteomic study, extensive fractionation of peptides generated from whole-cell trypsin digestion was achieved by coupling cIEF in the first-dimensional separation with capillary LC (RP-HPLC) in the second dimensional separation. Online analysis was performed using tandem mass spectra acquired by a linear ion trap mass spectrometer from triplicate runs. A total of 1749 and 1955 proteins with protein probability above 0.95 were identified from MDAH-2774 and TOV-112D after filtering through Peptide Prophet/Protein Prophet software. Differentially expressed proteins were further investigated by ingenuity pathway analysis (IPA) to reveal the association with important biological functions. Canonical pathway analysis using IPA demonstrates that important signaling pathways are highly associated with one of these two cell lines versus the other, such as the PI3K/AKT pathway, which is found to be significantly predominant in MDAH-2774 but not in TOV-112D. Also, protein network analysis using IPA highlights p53 as a central hub relating to other proteins from the connectivity map. These results illustrate the utility of high throughput proteomics methods using large-scale proteome profiling combined with bioinformatics tools to identify differential signaling pathways, thus contributing to the understanding of mechanisms of deregulation in neoplastic cells.

Differential actions of estrogen and SERMs in regulation of the actin cytoskeleton of endometrial cells

Estrogen and selective estrogen receptor modulators (SERMs) differentially impact endometrial cell function, however, the biological basis of these differences is not established. Deregulated cell adhesion to the extracellular matrix, cell movement and invasion are related to endometrial disorders, such as endometriosis or endometrial cancer. Remodeling of the actin cytoskeleton is required to achieve cell adhesion and movement. Estrogen receptor (ER) regulates actin and cell membrane remodeling through extra-nuclear signaling cascades. In this article, we show that administration of 17beta-estradiol (E2) and tamoxifen (TAM) to immortalized Ishikawa endometrial cells or to human endometrial stromal cells (ESC) results in remodeling of actin fibers and cell membrane. This is linked to rapid phosphorylation on Thr(558) of the actin-binding protein moesin and enhanced migration and invasion of normal and Ishikawa cells. Raloxifene (RAL) does not result in moesin activation or actin remodeling. When endometrial cells are exposed to E2 in the presence of TAM or RAL, both SERMs interfere with the recruitment of moesin, with the remodeling of the cytoskeleton, and with cell movement and migration induced by E2. The differential actions of E2, TAM and RAL are linked to a distinct modulation of the extra-nuclear signaling of ER to G proteins and to the Rho-associated kinase. These findings increase our understanding of the actions of estrogen and SERMs in endometrial cells and highlight potential molecular targets to interfere with the estrogen-related altered cell adhesion encountered in endometrial disorders.

The role of the membrane cytoskeleton cross-linker ezrin in medulloblastoma cells

Medulloblastoma is a highly malignant brain tumor that occurs predominantly in children. The molecular pathogenesis of medulloblastoma is under investigation. Previously, we used complementary DNA microarray analysis to compare patterns of gene expression in medulloblastoma samples versus normal cerebellum. The cytoskeletal protein ezrin was found to be overexpressed in medulloblastoma compared with normal cerebellum, an observation that was further validated by immunohistochemistry and real-time PCR analysis. To assess the role of ezrin in medulloblastoma, we studied ezrin's role in medulloblastoma migration, invasion, and adhesion. Western blotting and immunofluorescence showed high expression of ezrin in four medulloblastoma cell lines, and ezrin was primarily localized to filopodia. Ezrin-specific small interfering RNA suppressed the formation of filopodia and in vitro migration, invasion, and adhesion. We also used a stably transfected medulloblastoma cell line to study the effect of ezrin overexpression. We showed that high expression of ezrin promotes filopodia formation and in vitro invasion. Finally, athymic mice implanted with ezrin-overexpressing DAOY medullo-blastoma cell clones in the cerebellum showed shortened survival compared with controls. These findings suggest that, in addition to other cytoskeletal proteins, ezrin plays an important role in medulloblastoma adhesion, migration, and invasion.

Extra-nuclear signalling of estrogen receptor to breast cancer cytoskeletal remodelling, migration and invasion

BACKGROUND

Estrogen is an established enhancer of breast cancer development, but less is known on its effect on local progression or metastasis. We studied the effect of estrogen receptor recruitment on actin cytoskeleton remodeling and breast cancer cell movement and invasion. Moreover, we characterized the signaling steps through which these actions are enacted.

METHODOLOGY/PRINCIPAL FINDINGS

In estrogen receptor (ER) positive T47-D breast cancer cells ER activation with 17beta-estradiol induces rapid and dynamic actin cytoskeleton remodeling with the formation of specialized cell membrane structures like ruffles and pseudopodia. These effects depend on the rapid recruitment of the actin-binding protein moesin. Moesin activation by estradiol depends on the interaction of ER alpha with the G protein G alpha(13), which results in the recruitment of the small GTPase RhoA and in the subsequent activation of its downstream effector Rho-associated kinase-2 (ROCK-2). ROCK-2 is responsible for moesin phosphorylation. The G alpha(13)/RhoA/ROCK/moesin cascade is necessary for the cytoskeletal remodeling and for the enhancement of breast cancer cell horizontal migration and invasion of three-dimensional matrices induced by estrogen. In addition, human samples of normal breast tissue, fibroadenomas and invasive ductal carcinomas show that the expression of wild-type moesin as well as of its active form is deranged in cancers, with increased protein amounts and a loss of association with the cell membrane.

CONCLUSIONS/SIGNIFICANCE

These results provide an original mechanism through which estrogen can facilitate breast cancer local and distant progression, identifying the extra-nuclear G alpha(13)/RhoA/ROCK/moesin signaling cascade as a target of ER alpha in breast cancer cells. This information helps to understand the effects of estrogen on breast cancer metastasis and may provide new targets for therapeutic interventions.

Ezrin is a key element in the human vagina

OBJECTIVE

The vagina is a complex tubular structure that has reproductive, support and barrier functions. These depend on the cytoarchitecture of the vaginal cells, which is controlled by key proteins. Cytoskeletal proteins determine cell polarity and membrane specializations by integrating the actin cytoskeleton with cell membranes. This integration is the domain of cytoskeletal proteins including the MERM protein family (moesin-ezrin-radixin-Merlin). Nothing is known about the cyto-localization of the MERM's in the vaginal epithelium or how it influences the cytoarchitecture of the vaginal epithelium and stroma.

DESIGN

Full-thickness human vaginal fornix samples were obtained from 20 normal human specimens obtained at surgery for pelvic relaxation. Light- and electron microscopical immunohistochemistry (IHC) were used to identify and study activation and cellular localization of immuno-reactive-ezrin (ir-ezrin), a prototypical MERM.

RESULTS

Ir-ezrin was identified in the stratified squamous vaginal epithelium and connective tissue (fibroblasts, blood vessels and leucocytes). "H" scoring indicated that ir-ezrin staining is denser in the vaginal epithelium than in other layers, that the ir-ezrin staining was associated with increased keratinization and with the size of the tight junctions (p<0.01). Both the amounts and localization of ir-ezrin were associated with high levels of estrogen, identified by the menstrual history and keratinization of the superficial vaginal epithelium. The density of stromal ir-ezrin was increased in the presence of dense epithelial keratinization. Immuno-reactive-ezrin staining was most pronounced near the cell membranes of both keratinized and non-keratinized epithelium, indicating that ezrin activation (unfolding and movement to the membrane) had occurred. Ultra-structural examination of the epithelium showed intra-cellular ir-ezrin to be localized to junctional complexes that have been associated with decreased mucosal penetration by microorganisms. Ir-ezrin was widely distributed throughout stromal fibro-muscular cell, vessels and immunocytes.

CONCLUSIONS

MERM's, represented by ezrin, are widely present in the vaginal wall. This has implications for the strength and resilience of this tubular structure and may be the case in other internal genital tissues. Ezrin's localization and association with cell specializations indicate that in the vagina, as in other tissues, ezrin likely modulates vaginal cell-cell interactions including the changing vaginal cellular interface with the external environment, the regulation of the elasticity of the vagina, and the regulation of microbial and chemical traffic that determine the pH and microbial environment of the vagina. In other work we have shown that ezrin expression is induced by estradiol. The increase of ir-ezrin staining during the appearance of keratinization and maturation of the vaginal cytology indicates that estrogen may regulate vaginal ezrin and thereby the properties of the vaginal wall and epithelium.

Association of ezrin expression in intestinal and diffuse gastric carcinoma with clinicopathological parameters and tumor type

AIM: To investigate the correlation between ezrin expression and types of gastric carcinoma and clinico-pathological variables.

METHODS: We examined ezrin protein expression in 75 gastric carcinoma (53 intestinal types of adenocarcinoma, 22 diffuse types of carcinoma) tissues by immunohistochemistry. The results were compared with clinicopathological parameters such as tumor type, grade of tumor, clinical stage, presence of metastatic lymph node, and depth of invasion.

RESULTS: Ezrin immunostaining was positive in 43 cases (81.1%) of intestinal type and in 9 (40.9%) cases of diffuse type adenocarcinomas (P < 0.001). In gastric carcinomas, the expression of ezrin protein correlated with the status of H pylori and survival. There was no correlation between expression of ezrin with TNM stage and histological grade of gastric carcinomas (P > 0.05).

CONCLUSION: The low expression of ezrin implicates the loss of adhesion in diffuse carcinomas. Furthermore, overexpression of ezrin in carcinomas with H pylori infection may be a genuine specific pathway in which H pylori may cause/initiate gastric carcinoma.

Ezrin promotes ovarian carcinoma cell invasion and its retained expression predicts poor prognosis in ovarian carcinoma

The majority of patients diagnosed with ovarian carcinoma are classified as being in advanced stage of disease. In a situation of cancer spread throughout the abdominal cavity, a successful curative treatment is difficult to achieve. Therefore, preventing binding of tumor cells to the mesothelium is crucial for patients' outcome. One important mechanism is the interaction between hyaluronic acid and the CD44 receptor with its submembrane linking complex. This consists of ezrin, radixin, and moesin and connects the CD44 receptor with the cytoskeleton. To assess the role of ezrin and moesinfor ovarian carcinoma progression, we analyzed ovarian carcinoma samples from 105 patients for expression of ezrin and moesin by immunohistochemistry and correlated these data with several clinicopathological parameters. To elucidate the functional importance of ezrin and moesin, their expression was inhibited in SKOV-3 cells by RNA interference. Ezrin and moesin were strongly expressed in 49 and 48% of ovarian carcinoma samples, respectively, and their presence correlated with reduced overall survival in univariate analysis (ezrin, p=0.0189; moesin, p=0.0351). In multivariate analysis (including FIGO stage, residual tumor, histological type, and Silverberg grading), ezrin still remained significant as an independent risk factor (relative risk, 2.39; p=0.012). In SKOV-3 cells, siRNA against ezrin but not moesin inhibited in vitro invasion. These data imply that ezrin is necessary for tumor cell invasion, and the better prognosis of ovarian carcinomas lacking ezrin is probably related to their impaired invasion.

The membrane-cytoskeleton organizer ezrin is necessary for hepatocellular carcinoma cell growth and invasiveness

PURPOSE

The change of cell mobility is one of the preconditions of tumor metastasis. Cell skeleton alteration and rearrangement of F-actin was closely related to cell mobility. Ezrin is a membrane-cytoskeleton organizer that can mediate the rearrangement and the function of F-actin. In this paper, we investigated the effect of ezrin on hepatocellular carcinoma cell growth and invasiveness.

METHODS

Hepatocellular carcinoma cell lines such as MHCC-1, MHCC97-H, SF7721, SMMC7721, Hep3B, and HepG2 were chosen in this study. We first examined the expression and the distribution of ezrin and F-actin in these cell lines using immunofluorescence, RT-PCR, and the western blot. Next we used small interfering RNA (siRNA) to down-regulate ezrin expression in MHCC-1, MHCC97-H, SF7721, and HepG2 to investigate the role of ezrin in tumor cell growth and invasiveness.

RESULTS

Our preliminary results showed that the expression of ezrin and gamma-actin in MHCC-1, MHCC97-H, and SF7721 with higher metastatic potential were obviously up-regulated than those in SMMC7721, Hep3B, and HepG2 with lower potential. No different expression of beta-actin was found in the above tumor cell lines. The outcome of RNAi indicated that decreasing ezrin expression can notably inhibit the proliferation of the four hepatocellular carcinoma cell lines (p < 0.01, n = 10). The proportion of cells in G2-M phase also decreased after RNAi. The number of pseudopods decreased as well after RNAi treatment (p < 0.01, n = 5). The mobility and invasiveness of cancer cells decreased with decreasing ezrin expression tested by transwell assay (p < 0.01, n = 8).

CONCLUSION

Ezrin plays an important role in the process of hepatocellular carcinoma cell proliferation, migration, and invasiveness.

Estrogen receptor alpha interacts with Galpha13 to drive actin remodeling and endothelial cell migration via the RhoA/Rho kinase/moesin pathway

Sex steroids control cell movement and tissue organization; however, little is known of the involved mechanisms. This report describes the ongoing dynamic regulation by estrogen of the actin cytoskeleton and cell movement in human vascular endothelial cells that depends on rapid activation of the actin-regulatory protein moesin. Moesin activation is triggered by the interaction of the C-terminal portion of cell membrane estrogen receptor alpha with the G protein Galpha(13), leading to activation of the small GTPase RhoA and of the downstream effector Rho-associated kinase. The resulting phosphorylation of moesin on Thr(558) is the means of moesin's binding to actin and the remodeling of the actin cytoskeleton. This cascade of events ensues within minutes of estradiol administration and results in changes in cell morphology and to the development of specialized cell membrane structures such as ruffles and pseudopodia that are necessary for cell movement. These findings expand our knowledge of the basis of estrogen's effects on human cells, including the regulation of actin assembly, cell movement and migration. They highlight novel pathways of signal transduction of estrogen receptor alpha through nontranscriptional mechanisms. Furthermore, exposure of this estrogen receptor-dependent, nongenomic action of estrogen on human vascular endothelial cells is especially relevant to the present interest in the role of estrogen in cardiovascular protection.

Abnormal ezrin localization is associated with clinicopathological features in invasive breast carcinomas

The membrane-cytoskeleton crosslinker ezrin is associated with malignant progression and metastasis in human neoplasias. To study the role of ezrin in breast cancer, we first assessed ezrin expression in a panel of breast cancer cell lines by western blot and confocal microscopy. Western blot revealed no differences in total ezrin levels among these breast cell lines. However, immunofluorescence staining revealed that Estrogen receptor (ER)-positive, noninvasive and nontumorigenic cell lines concentrated ezrin at the apical surface, whereas invasive cell lines localized ezrin in motile structures (membrane ruffles and filopodia) but also had more diffuse cytoplasmic staining. We next studied ezrin expression in 509 breast carcinomas using tissue microarrays. Immunohistochemical staining for ezrin, p53, Ki-67, phospho-Akt, HER2, and hormonal receptors was performed. Ezrin staining in normal breast epithelium localized at the apical, but not lateral, cell surface, whereas, in most breast tumor cases (331, 70.3%), it localized in the cytoplasm. Complete membranous staining occurred in 89 (18.9%) samples, and apical staining was seen in 51 (10.8%) cases. There were significant positive associations between cytoplasmic ezrin localization and adverse tumor characteristics such as high grade, high level of Ki-67 expression, hormonal-receptor negativity, and lymph-node metastases. Apical ezrin staining was associated with favorable clinicopathological features and node-negative tumors. Membranous ezrin staining was associated with high grade, strong HER2 and p-Akt expression. In conclusion, the switch of ezrin localization from the apical membrane to either the complete membrane or to the cytoplasm is correlated with dedifferentiation and adverse features in invasive breast tumors and cancer cell lines.

Involvement of adaptor protein Crk in malignant feature of human ovarian cancer cell line MCAS

Signaling adaptor protein Crk regulates cell motility and growth through its targets Dock180 and C3G, those are the guanine-nucleotide exchange factors (GEFs) for small GTPases Rac and Rap, respectively. Recently, overexpression of Crk has been reported in various human cancers. To define the role for Crk in human cancer cells, Crk expression was targeted in the human ovarian cancer cell line MCAS through RNA interference, resulting in the establishment of three Crk knockdown cell lines. These cell lines exhibited disorganized actin fibers, reduced number of focal adhesions, and abolishment of lamellipodia formation. Decreased Rac activity was demonstrated by pull-down assay and FRET-based time-lapse microscopy, in association with suppression of both motility and invasion by phagokinetic track assay and transwell assay in these cells. Furthermore, Crk knockdown cells exhibited slow growth rates in culture and suppressed anchorage-dependent growth in soft agar. Tumor forming potential in nude mice was attenuated, and intraperitoneal dissemination was not observed when Crk knockdown cells were injected into the peritoneal cavity. These results suggest that the Crk is a key component of focal adhesion and involved in cell growth, invasion, and dissemination of human ovarian cancer cell line MCAS.

Effects of Advanced Glycation End Products on Ezrin-Dependent Functions in LLC-PK1 Proximal Tubule Cells

We have recently shown that advanced glycation products (AGEs) bind to the ERM (ezrin, radixin, moesin) family of proteins. ERM proteins act as cross-linkers between cell membrane proteins and the actin cytoskeleton. They are also involved in signal transduction pathways. They therefore have a critical role in normal cell processes, including modulation of cell shape, adhesion, and motility. We postulate that AGEs may contribute to diabetic complications by disrupting ERM function. In support of this hypothesis, AGEs inhibit ezrin-dependent tubulogenesis of proximal tubule cells. Phosphorylation is an important activating mechanism for ERM proteins, and AGEs inhibit ezrin phosphorylation mediated by the epidermal growth factor receptor.

Functional duality of merlin: A conundrum of proteome complexity

Merlin and ezrin proteins belong to the same gene family, i.e., MERM containing merlin, ezrin radixin and moesin. Members of this family possess an extensive homology in their amino acid sequences. It has been shown that merlin is a tumor suppressor, while ezrin is a promoter in tumor progression. The expression of these two proteins is commonly found inversely proportional to each other in cancer cells, i.e. down-regulation of merlin concomitant with over-expression of ezrin and vice versa. However, when determining merlin and ezrin in ovarian carcinoma cells, we have observed that both merlin and ezrin could be over-expressed simultaneously in some ovarian cancer (OVCA) cell lines and OVCA ascites cells, suggesting that merlin could be an oncoprotein rather than a tumor suppressor protein in certain OVCA cells. The functional duality of merlin might represent a paradigm in proteome complexity and is especially important in investigating multifactorial diseases such as cancer.

Variation in gene expression patterns in effusions and primary tumors from serous ovarian cancer patients

Background

While numerous studies have characterized primary ovarian tumors, little information is available regarding expression patterns of metastatic sites of this cancer. To define sets of genes that distinguish primary and metastatic ovarian tumors, we used cDNA microarrays to characterize global gene expression patterns in 38 effusions (28 peritoneal, 10 pleural) and 8 corresponding primary ovarian tumors, and searched for associations between expression patterns and clinical parameters.

Results

We observed multidimensional variation in expression patterns among the cancers. Coordinate variation in expression of genes from two chromosomal regions, 8q and 19q, was seen in subsets of the cancers indicating possible amplifications in these regions. A set of 112 unique genes of known function was differentially expressed between primary tumors and effusions using supervised analysis. Relatively few differences were seen between effusions isolated from the pleural and peritoneal cavities or between effusions from patients diagnosed with stage III and stage IV cancers. A set of 84 unique genes was identified that distinguished high from lower grade ovarian cancers. The results were corroborated using immunocytochemistry, mRNA in situ hybridization, and immunoblotting.

Conclusion

The extensive variation in expression patterns observed underscores the molecular heterogeneity of ovarian cancer, but suggests a similar molecular profile for ovarian carcinoma cells in serosal cavities.