High level of ezrin mRNA expression in an osteosarcoma biopsy sample with lung metastasis

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.

Evaluating a Panel of Autoantibodies Against Tumor-Associated Antigens in Human Osteosarcoma

Background: The aim of this study was to identify a panel of candidate autoantibodies against tumor-associated antigens in the detection of osteosarcoma (OS) so as to provide a theoretical basis for constructing a non-invasive serological diagnosis method in early immunodiagnosis of OS. Methods: The serological proteome analysis (SERPA) approach was used to select candidate anti-TAA autoantibodies. Then, indirect enzyme-linked immunosorbent assay (ELISA) was used to verify the expression levels of eight candidate autoantibodies in the serum of 51 OS cases, 28 osteochondroma (OC), and 51 normal human sera (NHS). The rank-sum test was used to compare the content of eight autoantibodies in the sera of three groups. The diagnostic value of each indicator for OS was analyzed by an ROC curve. Differential autoantibodies between OS and NHS were screened. Then, a binary logistic regression model was used to establish a prediction logistical regression model. Results: Through ELISA, the expression levels of seven autoantibodies (ENO1, GAPDH, HSP27, HSP60, PDLIM1, STMN1, and TPI1) in OS patients were identified higher than those in healthy patients (p < 0.05). By establishing a binary logistic regression predictive model, the optimal panel including three anti-TAAs (ENO1, GAPDH, and TPI1) autoantibodies was screened out. The sensitivity, specificity, Youden index, accuracy, and AUC of diagnosis of OS were 70.59%, 86.27%, 0.5686, 78.43%, and 0.798, respectively. Conclusion: The results proved that through establishing a predictive model, an optimal panel of autoantibodies could help detect OS from OC or NHS at an early stage, which could be used as a promising and powerful tool in clinical practice.

Knockdown of Ezrin inhibited migration and invasion of cervical cancer cells in vitro

Cervical cancer is the fourth most common malignancy in women. The aim of this study was to investigate the functions of Ezrin in cervical cancer cells. Two cervical cancer cell lines, SiHa and CaSki, were cultured in vitro. Following the knockdown of Ezrin using siRNA, real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis were applied to analyze Ezrin expression at the messenger RNA (mRNA) and protein levels. Subsequently, wound healing assay, transwell assay, and sulforhodamine B (SRB) assay were used to detect the migration, invasion, and viability of cervical cancer cells, respectively. Results revealed that Ezrin siRNA can notably inhibit the migration and invasion of SiHa and CaSki cells (P < 0.05). However, knockdown of Ezrin shows no effects on the viability of SiHa and CaSki cells (P < 0.05). It is indicated that Ezrin plays a possible role in promoting the migration and invasion of cervical cancer cells and may be a therapeutic target to prevent metastasis of cervical cancer.

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

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

Targeted Chemotherapy in Bone and Soft-Tissue Sarcoma

Historically surgical intervention has been the mainstay of therapy for bone and soft-tissue sarcomas, augmented with adjuvant radiation for local control. Although cytotoxic chemotherapy revolutionized the treatment of many sarcomas, classic treatment regimens are fraught with side effects while outcomes have plateaued. However, since the approval of imatinib in 2002, research into targeted chemotherapy has increased exponentially. With targeted therapies comes the potential for decreased side effects and more potent, personalized treatment options. This article reviews the evolution of medical knowledge regarding sarcoma, the basic science of sarcomatogenesis, and the major targets and pathways now being studied.

Biological characterization of preclinical Bioluminescent Osteosarcoma Orthotopic Mouse (BOOM) model: A multi-modality approach

Osteosarcoma (OS) is a bone malignancy that affects children and adolescents. It is a highly aggressive tumor and typically metastasizes to lungs. Despite aggressive chemotherapy and surgical treatments, the current 5 year survival rate is 60–70%. Clinically relevant models are needed to understand OS pathobiology, metastatic progression from bones to lungs, and ultimately, to develop more efficacious treatment strategies and improve survival rates in OS patients with metastasis. The main goal of this study was to develop and characterize an in vivo OS model that will allow non-invasive tracking of tumor progression in real time, and aid in studying OS pathobiology, and screening of potential therapeutic agents against OS. In this study, we have used a multi-modality approach using bioluminescent imaging, electron microscopy, micro-computed tomography, and histopathology to develop and characterize a preclinical Bioluminescent Osteosarcoma Orthotopic Mouse (BOOM) model, using 143B human OS cell line. The results of this study clearly demonstrate that the BOOM model represents the clinical disease as evidenced by a spectrum of changes associated with tumor establishment, progression and metastasis, and detection of known OS biomarkers in the primary and metastatic tumor tissue. Key novel findings of this study include: (a) multimodality approach for extensive characterization of the BOOM model using 143B human OS cell line; (b) evidence of renal metastasis in OS orthotopic model using 143B cells; (c) evidence of Runx2 expression in the metastatic lung tissue; and (d) evidence of the presence of extracellular membrane vesicles and myofibroblasts in the BOOM model.

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.

Establishment and characterization of a new highly metastatic human osteosarcoma cell line

Osteosarcoma is the most common primary malignancy of bone in children and young adults. There is a paucity of tumorigenic and highly metastatic human osteosarcoma cell lines that have not been further transformed by exogenous means. Here we establish and characterize a highly metastatic human osteosarcoma cell line that is derived from a poorly metastatic MG63 line through serial passage in nude mice via intratibial injections. The occasional pulmonary metastases developed from MG63 were harvested and repassaged in mice until a highly metastatic subline (MG63.2) was established. The parental MG63 and highly metastatic MG63.2 cells were further characterized in vitro and in vivo. MG63.2 cells demonstrated increased cell migration and invasion compared to the parental MG63 cells. Conversely, cell adhesion was significantly greater in MG63 cells when compared to the MG63.2 cells. MG63.2 cells grew at a slightly slower rate than that of the parental cells. When injected into nude mice, MG63.2 cells had a greater than 200-fold increase in developing pulmonary metastases compared to the parental MG63 cells. MG63.2 cells also formed larger primary tumors when compared to the parental MG63 cells. Further analysis revealed that ezrin expression was up-regulated in the metastatic MG63.2 cells. Interestingly, expressions of MMP-2 and MMP-9 were down-regulated, and expression of TIMP-2 was up-regulated in the MG63.2 cells. Taken together, we have established and characterized a highly metastatic human osteosarcoma cell line that should serve as a valuable tool for future investigations on the pathogenesis, metastasis, and potential treatments of human osteosarcoma.

Sp1 and AP-1 regulate expression of the human gene VIL2 in esophageal carcinoma cells

Ezrin, encoded by VIL2, is a membrane-cytoskeletal linker protein that has been suggested to be involved in tumorigenesis. Ezrin expression in esophageal squamous cell carcinoma (ESCC) was described recently, but its clinical significance and the molecular mechanism underlying its regulated expression remain unclear. Thus, we retrospectively evaluated ezrin expression by immunohistochemistry in a tissue microarray representing 193 ESCCs. Ezrin overexpression in 90 of 193 tumors (46.6%) was associated with poor survival (p = 0.048). We then explored the mechanism by which ezrin expression is controlled in ESCC by assessing the transcriptional regulatory regions of human VIL2 by fusing deletions or site-directed mutants of the 5'-flanking region of the gene to a luciferase reporter. We found that the region -87/-32 containing consensus Sp1 (-75/-69) and AP-1 (-64/-58) binding sites is crucial for VIL2 promoter activity in esophageal carcinoma cells (EC109) derived from ESCC. AP-1 is comprised of c-Jun and c-Fos. Electrophoretic mobility shift and chromatin immunoprecipitation experiments demonstrated that Sp1 and c-Jun bound specifically to their respective binding sites within the VIL2 promoter. In addition, transient expression of Sp1, c-Jun, or c-Fos increased ezrin expression and VIL2 promoter activity. Use of selective inhibitors revealed that VIL2 transactivation required the MEK1/2 signal transduction pathway but not JNK or p38 MAPK. Taken together, we propose a possible signal transduction pathway whereby MEK1/2 phosphorylates ERK1/2, which phosphorylates Sp1 and AP-1 that in turn bind to their respective binding sites to regulate the expression of human VIL2 in ESCC cells.

Metastatic osteosarcoma gene expression differs in vitro and in vivo

An understanding of differential gene expression in highly metastatic osteosarcoma could provide gene targets for treatment of metastases. We compared gene expression profiles of high- (LM7) and low- (LM2) metastatic SaOS2-derived cell lines in an in vitro tissue culture model and examined several differentially regulated genes in vivo in a murine orthotopic xenograft model. We hypothesized an orthotopic inoculation of LM2 and LM7 cells would establish a primary lesion and the gene expression profile of cells grafted in this fashion would resemble the gene expression profile observed in an in vitro model. Thirty-five days after inoculation, animals were euthanized and both tibiae were harvested and rapidly frozen in liquid nitrogen. Human-specific GAPDH mRNA was present in two of four tibias inoculated with LM2 cells and three of four tibias inoculated with LM7 cells. Tibiae displaying the presence of human cells were assayed by semiquantitative reverse transcriptase polymerase chain reaction. We observed poor correspondence of in vitro to in vivo gene expression for either cell line. Accordingly, in vitro osteosarcoma gene expression data must be interpreted with caution until confirmed in vivo. Our orthotopic injection model allowed in vivo study of differential gene expression between these two cell lines but did not show radiographic evidence of an established primary lesion.