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

Special AT-rich sequence binding protein 1 promotes multidrug resistance in gastric cancer by regulation of Ezrin to alter subcellular localization of ATP-binding cassette transporters

Multidrug resistance is a primary factor in the poor response to chemotherapy and subsequent death in gastric cancer patients. However, the molecular mechanisms involved remain unclear. In this study, the high expression of special AT-rich sequence binding protein 1 (SATB1) in gastric cancer was found to be associated with reduced sensitivity to various chemotherapy drugs. Our results demonstrate that SATB1 can promote chemotherapy resistance in gastric cancer in vitro and in vivo. SATB1 exerts its effect by enhancing the activity of multiple ATP-binding cassette (ABC) transporters (P-glycoprotein, multidrug resistance-associated protein, and breast cancer resistance protein) in gastric cancer cell lines. We also found that SATB1 affects ABC transporters by altering the subcellular localization of the ABC transporter rather than its expression. Subsequently, we confirmed that Ezrin binds to various ABC transporters and affects their subcellular localization. In addition, we found that SATB1 can also bind to the Ezrin promoter and regulate its expression. In the present study, we elucidate the mechanism of SATB1-mediated multidrug resistance in gastric cancer, providing a basis for SATB1 as a potential target for reversal of resistance.

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.

Expressions of ezrin, ERK, STAT3, and AKT in tongue cancer and association with tumor characteristics and patient survival

Background

Ezrin, ERK, STAT3, and AKT are proteins that are overexpressed in various types of cancer, although their expressions in tongue cancer has received less focus. This study aimed to address associations between the expression levels of these proteins and with characteristics of the tumor and patient survival.

Methods

We performed immunohistochemical staining of ezrin, ERK, STAT3, and AKT in tumors from patients with tongue carcinoma in situ (CIS, n = 17) and tongue squamous cell carcinoma (SCC, n = 46). Statistical differences between the SCC versus the CIS cohorts were estimated by calculations of bivariate odds ratios of low versus high expression of the proteins. Fisher's exact tests were used to appraise interassociations between the proteins, as well as expression levels versus patient and tumor characteristics. Survival based on Kaplan–Meier statistics in combination log‐rank tests were used to address potential effects of the patient and tumor characteristics versus 5‐year survival rate.

Results

The relative high: low expression of all four proteins in the two cohorts differed, and particularly ERK was markedly overexpressed in the SCC versus the CIS cohort (odds ratio = 45.3, p < .01). The relative high: low expression each protein versus patient and tumor characteristics; showed associations between AKT expression and T stage (p = .002) plus node metastases (p = .12), and between ERK expression and drinking (p = .01) and smoking history (p = .01). There was no significant difference observed between ERK and the three other molecules, nor any significant difference between the degree of expression of each protein and the 5‐year disease‐specific survival rate.

Conclusion

Ezrin, ERK, STAT3, and AKT appear to be involved in the progress from carcinoma in situ in the tongue into squamous cell carcinoma. ERK in particular is overexpressed, suggesting that ERK may be a novel therapeutic target for preventing tongue cancer.

microRNA-211 regulates cell proliferation, apoptosis and migration/invasion in human osteosarcoma via targeting EZRIN

Background

In recent years, microRNA-211 (miR211) has been considered as a tumor suppressor in multiple malignancies. However, the function of miR211 in human osteosarcoma has not been explored intensively so far. In this study, the relationship between miR211 and EZRIN was analyzed in human osteosarcoma.

Methods

The expression levels of miR211 and EZRIN were measured in both human osteosarcoma cells and tissues. The direct regulatory relationship between miR211 and EZRIN was evaluated using dual-luciferase assay. The effect of miR211 and EZRIN overexpression on cell proliferation, migration/invasion, and apoptosis was detected.

Results

The expression of miR211 was obviously lower in osteosarcoma tissues than paracancerous tissues. EZRIN was identified as the direct target of miR211, and up-regulation of miR211 increased the percentage of cell apoptosis, and suppressed cell proliferation as well as cell migration/invasion via directly regulating EZRIN.

Conclusions

Our study indicated that miR211 has an important role in the development and progress of osteosarcoma, and it might become a novel target in the diagnosis and treatment of human osteosarcoma.

Electronic supplementary material

The online version of this article (10.1186/s11658-019-0173-x) contains supplementary material, which is available to authorized users.

Ezrin contributes to cervical cancer progression through induction of epithelial-mesenchymal transition

Cervical cancer is the third most common cancer in females worldwide. The treatment options for advanced cervical cancer are limited, leading to high mortality. Ezrin is a membrane-cytoskeleton-binding protein recently reported to act as a tumor promoter, and we previously indicated that the aberrant localization and overexpression of Ezrin could be an independent effective biomarker for prognostic evaluation of cervical cancers. In this study, we identified Ezrin as a regulator of epithelial-mesenchymal transition (EMT) and metastasis in cervical cancer. Ezrin knock-down inhibited anchorage-independent growth, cell migration, and invasion of cervical cancer cell lines in vitro and in vivo. EMT was inhibited in Ezrin-depleted cells, with up-regulation of E-cadherin and Cytokeratin-18 (CK-18) and down-regulation of mesenchymal markers. Ezrin knock-down also induced Akt phosphorylation. These results implicate Ezrin as an EMT regulator and tumor promoter in cervical cancer, and down-regulation of Ezrin suppressed cervical cancer progression, possibly via the phosphoinositide 3-kinase/Akt pathway. Furthermore, the expression pattern of Ezrin protein was closely related with the lymphovascular invasion status of cervical cancer by immunohistochemistry, and the survival analysis revealed that the cervical cancer patients with the perinuclear Ezrin expression pattern had longer survival time than those with the cytoplasmic Ezrin expression pattern. Ezrin thus represents a promising target for the development of novel and effective strategies aimed at preventing the progression of cervical cancer.

Resistin, a fat-derived secretory factor, promotes metastasis of MDA-MB-231 human breast cancer cells through ERM activation

Resistin, an adipocyte-secreted factor, is known to be elevated in breast cancer patients. However, the molecular mechanism by which resistin acts is not fully understood. The aim of this study was to investigate whether resistin could stimulate invasion and migration of breast cancer cells. Here, we report that resistin stimulated invasion and migration of breast cancer cells as well as phosphorylation of c-Src. Inhibition of c-Src blocked resistin-induced breast cancer cell invasion. Resistin increased intracellular calcium concentration, and chelation of intracellular calcium blocked resistin-mediated activation of Src. Resistin also induced phosphorylation of protein phosphatase 2A (PP2A). Inhibition of c-Src blocked resistin-mediated PP2A phosphorylation. In addition, resistin increased phosphorylation of PKCα. Inhibition of PP2A enhanced resistin-induced PKCα phosphorylation, demonstrating that PP2A activity is critical for PKCα phosphorylation. Resistin also increased phosphorylation of ezrin, radixin, and moesin (ERM). Additionally, ezrin interacted with PKCα, and resistin promoted co-localization of ezrin and PKCα. Either inhibition of c-Src and PKCα or knock-down of ezrin blocked resistin-induced breast cancer cells invasion. Moreover, resistin increased expression of vimentin, a key molecule for cancer cell invasion. Knock-down of ezrin abrogated resistin-induced vimentin expression. These results suggest that resistin play as a critical regulator of breast cancer metastasis.

Clinicopathological significance of microRNA-214 in gastric cancer and its effect on cell biological behaviour

Accumulating evidence indicates that numerous microRNAs are involved in the tumorigenesis and progression of gastric cancer, while the clinical significance of microRNA-214 in gastric cancer is poorly understood and the exact role of microRNA-214 in gastric cancer remains obscure. In the present study, expression levels of microRNA-214 in 80 gastric carcinoma tissues, 18 nontumourous gastric tissues, and 4 types of gastric cancer cell lines were quantified by reverse transcription followed by real-time quantitative polymerase chain reaction (RT-qPCR), and the relationship between microRNA-214 expression and cliniopathological characteristics including prognosis was explored. To investigate the potential role of microRNA-214 in gastric cancer cell biological behaviour, we performed cell proliferation, apoptosis, migration and invasion assays in four gastric cancer cell lines and an immortalized gastric cell line in vitro. Our results showed that microRNA-214 was dramatically downregulated in gastric cancer tissues and gastric cancer cell lines, compared with nontumourous gastric tissues. Stepwise downregulation of microRNA-214 expression was observed among nontumourous gastric mucosa, nonmetastasis gastric cancer tissues, and metastasis gastric cancer tissues. The expression of microRNA-214 was significantly inversely correlated with lymph node metastasis and tumour size but had no correlation with the patient's prognosis. Ectopic expression of microRNA-214 could inhibit cell migration and invasion ability in SGC7901 and MKN45 gastric cancer cells. And knockdown of microRNA-214 significantly facilitated cell proliferation, migration and invasion in a cell-specific manner in MKN28, BGC823 and GES-1 cells. Colony stimulating factor 1 (CSF1) was identified as a target gene of microRNA-214. In summary, our data demonstrated that microRNA-214 is a promising novel biomarker for lymph node metastasis in patients with gastric cancer. And we identified that downregulation of microRNA-214 may regulate the proliferation, invasion and migration of gastric cancer cells by directly targeting CSF1.

Desmoglein 3 promotes cancer cell migration and invasion by regulating activator protein 1 and protein kinase C-dependent-Ezrin activation

Desmoglein 3 (Dsg3), the pemphigus vulgaris antigen, has recently been shown to be upregulated in squamous cell carcinoma (SCC) and has been identified as a good tumor-specific marker for clinical staging of cervical sentinel lymph nodes in head and neck SCC. However, little is known about its biological function in cancer. The actin-binding protein Ezrin and the activator protein 1 (AP-1) transcription factor are implicated in cancer progression and metastasis. Here, we report that Dsg3 regulates the activity of c-Jun/AP-1 as well as protein kinase C (PKC)-mediated phosphorylation of Ezrin-Thr567, which contributes to the accelerated motility of cancer cells. Ectopic expression of Dsg3 in cancer cell lines caused enhanced phosphorylation at Ezrin-Thr567 with concomitant augmented membrane protrusions, cell spreading and invasive phenotype. We showed that Dsg3 formed a complex with Ezrin at the plasma membrane that was required for its proper function of interacting with F-actin and CD44 as Dsg3 knockdown impaired these associations. The increased Ezrin phosphorylation in Dsg3-overexpressing cells could be abrogated substantially by various pharmacological inhibitors for Ser/Thr kinases, including PKC and Rho kinase that are known to activate Ezrin. Furthermore, a marked increase in c-Jun S63 phosphorylation, among others, was found in Dsg3-overexpressing cells and the activation of c-Jun/AP-1 was further supported by a luciferase reporter assay. Taken together, our study identifies a novel Dsg3-mediated c-Jun/AP-1 regulatory mechanism and PKC-dependent Ezrin phosphorylation that could be responsible for Dsg3-associated cancer metastasis.

Mechanisms underlying cancer progression caused by ezrin overexpression in tongue squamous cell carcinoma

BACKGROUND

Ezrin is a member of the ezrin, radixin, and moesin family that provides a functional link between the plasma membrane and the cortical actin cytoskeleton. A correlation between ezrin overexpression and aggressive cancer behavior has been recently reported in various tumor types. However, its roles in the mechanisms underlying progression of tongue squamous cell carcinoma (SCC) are unclear.

METHOD

We used human tongue SCC and noncancerous tissue microarrays to immunohistochemically analyze the ezrin expression level and its relationship with proliferative activity. The human tongue SCC cell line HSC-3 was used to determine the effects of ezrin RNA interference (RNAi) on cancer cells during MTT; wound healing and invasion assays; immunofluorescence of the actin cytoskeleton; and western blotting of E-cadherin, N-cadherin, β-catenin, and the active and total RhoA/Rac1/cdc42.

RESULTS

Ezrin was overexpressed in 46.4% of the tumors examined in human tongue SCC tissue microarrays. Ezrin expression was correlated with the Ki-67 index. Ezrin depletion by RNAi in the HSC-3 cells significantly reduced cell proliferation, migration, and invasiveness and disturbed actin reorganization during podia formation. Its effects on RhoA/Rac1/cdc42 expression were not significant, whereas it enhanced E-cadherin and β-catenin expression and decreased N-cadherin expression.

CONCLUSIONS

Ezrin is often overexpressed in primary tongue SCCs and may have an important role in their growth, migration, and invasiveness possibly via its relationship with the E-cadherin/β-catenin complex and the cadherin switch. Thus, ezrin could be a therapeutic target in tongue SCC.

Ezrin expression and its phosphorylation in gastric carcinoma with lymphoid stroma and Epstein-Barr virus infection

Gastric carcinoma with lymphoid stroma (GCLS) is a unique variant of gastric carcinoma that represents prominent lymphocytic infiltration and is correlated with Epstein-Barr virus (EBV) infection. Ezrin expression and activation are crucial in tumor metastasis and induce cell migration of EBV-related nasopharyngeal carcinomas. Using immunohistochemical methods, the expression of total and phosphorylated ezrin (p-ezrin), Thr567, was examined in 104 GCLS cases, including 78 EBV-positive and 26 EBV-negative cases, as well as 29 non-GCLS cases. Positive ezrin expression was detected to be at markedly higher levels in GCLS compared to non-GCLS (P<0.0001). Furthermore, ezrin expression was detected to be at higher levels in EBV-positive compared to EBV-negative GCLS (P=0.0294). High expression of p-ezrin in GCLS was associated with positive lymph node metastasis (P=0.0187). In summary, these results demonstrated that ezrin overexpression is correlated with the histologic characteristics of GCLS and EBV infection. Phosphorylation of ezrin may, therefore, contribute to lymph node metastasis in GCLS.

Ezrin overexpression predicts the poor prognosis of gastric adenocarcinoma

Background

Ezrin is a cytoskeletal protein that is involved in tumor growth and invasion. It has been suggested that Ezrin expression plays an important role in tumor metastasis. This study is aimed to investigate the clinicopathological significance of Ezrin overexpression in gastric adenocarcinomas.

Methods

Ezrin protein expression was examined by immunohistochemistry in 26 normal gastric mucosa, 32 dysplasia, and 277 gastric adenocarcinomas. The relationship between Ezrin expression and the clinicopathological features of gastric cancers was analyzed. In addition, a gastric cancer cell line, MKN-1, was also used for immunofluorescence staining to evaluate the distribution of Ezrin protein.

Results

Ezrin protein located in the cytoplasm and/or membrane in the migrating gastric cancer cells, and it mainly concentrated at the protrusion site; however, only cytoplasmic distribution was observed in the non-migrating cancer cells by immunofluorescence staining. The positive rate of Ezrin protein expression was significantly higher in gastric adenocarcinoma and dysplasia compared with that in the normal gastric mucosa. Moreover, expression frequency of Ezrin protein increased significantly in lymph node metastasis and late clinical stages. Consistently, strong expression of Ezrin was significantly correlated with poor prognosis of gastric cancer.

Conclusion

The detection of Ezrin expression can be used as the marker for early diagnosis and prognosis of gastric adenocarcinoma.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2303598677653946

Ezrin is associated with gastric cancer progression and prognosis

To investigat the clinical significance of Ezrin in the development and progression of gastric cancer. Immunohistochemistry was employed to analyze Ezrin expression in 436 clinicopathologically characterized gastric cancer cases. Ezrin protein levels were up-regulated in gastric cancer lesions compared with adjacent noncancerous tissues. Positive expression of Ezrin correlated with age, size of tumor, location of tumor, depth of invasion, vessel invasion, lymph node and distant metastasis and TNM stage. In stages I, II and III, the 5 year survival rate of patients with a high expression of Ezrin was significantly lower than those in patients with low expression. In stage IV, Ezrin expression did not correlate with the 5 year survival rate. Further multivariate analysis suggested that the depth of invasion, lymph node and distant metastasis, TNM stage, and up-regulation of Ezrin were independent prognostic indicators for the disease. Expression of Ezrin in gastric cancer is significantly associated with lymph node and distant metastasis, and poor prognosis. Ezrin protein could be useful markers to predict tumor progression and prognosis.

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.