Ezrin in osteosarcoma: Comparison between conventional high-grade and central low-grade osteosarcoma

Intramedullary Well-differentiated Osteosarcoma: Imaging and Pathologic Findings in 17 Patients

BACKGROUND

Intramedullary well-differentiated osteosarcoma (IMWDOS) is rare and may easily be misdiagnosed.

OBJECTIVE

This study aimed at investigating the clinical, imaging, and pathological features of IMWDOS for correct diagnosis.

MATERIALS AND METHODS

Seventeen patients with IMWDOS were enrolled, and their clinical, imaging, and pathological data were analyzed.

RESULTS

Total 13 males and 4 females aged 19-55 years (mean 36. 1) were selected. The lesion was located at long bones in 16 patients and the second region of the acetabulum in one patient. Except for three patients with limited areas of lesions, all the other patients had a wide distribution of tumor, and the lesion in long bones involved the metaphysis area with possible extension towards the diaphysis. In imaging, the lesion usually had an unclear boundary with the destruction of bone cortex, uneven thickness of the bone cortex, thick and coarse trabecula in the lesion, but few periosteal reactions and soft tissue masses. The lesion was histologically composed of spindle cells with slight atypia. Follow-up was performed 2-101 months (mean 31.9m) in 14 cases, 10 years in one case, and 26 years in the remaining two. At follow-up, 12 patients (12/17 or 70.6%) who had a complete resection, including amputation (n=2), wide excision (n=8), and endoprosthetic replacement (n=2), showed no recurrence or metastasis. Among five patients who underwent curettage, three (3/17 or 17.6%) had recurrent lesions, leading to death in two of them, and the third one died during post-operation chemotherapy.

CONCLUSION

Intramedullary well-differentiated osteosarcoma tends to occur at the metaphysis of long bones, especially at the distal femur. Histological, clinical, and imaging findings lack specific characteristics and should be examined collectively to reach a correct diagnosis. The prognosis of patients with complete lesion resection is good, while incomplete lesion curettage or resection will lead to recurrence and transformation into a highly malignant tumor.

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.

Adenovirus-mediated small interfering RNA targeting ezrin induces apoptosis and inhibits metastasis of human osteosarcoma MG-63 cells

Osteosarcoma is a disease prone to recurrence and metastasis, and adenovirus expression vector is frequently studied as a therapeutic target of osteosarcoma in recent years. The present study attempts to explore the effect of adenovirus-mediated siRNA targetting ezrin on the proliferation, migration, invasion, and apoptosis of human osteosarcoma MG-63 cells. Human osteosarcoma MG-63 cell line was selected for construction of recombinant adenovirus vector. The mRNA and protein levels of ezrin, Bcl2-associated X protein (Bax), B cell lymphoma-2 (Bcl-2), p21, p53, Caspase-3, matrix metalloproteinase (MMP) 2 (MMP-2) and MMP-9, Cyclin D1, and cyclin-dependent kinase 4a (CDK4a) were determined. Through ELISA, the levels of Caspase-3, MMP-2 and MMP-9 were examined. Finally, human osteosarcoma MG-63 cell viability, growth, invasion, migration, and apoptosis were detected. Initially, adenovirus expression vector of ezrin was constructed by ezrin 2 siRNA sequence. Adenovirus-mediated siRNA targetting ezrin reduced expression of ezrin in MG-63 cells. The results revealed that adenovirus-mediated siRNA targetting ezrin elevated expression levels of Bax, p21, p53, and Caspase-3, Cyclin D1, and CDK4a and reduced expression levels of Bcl-2, MMP-2 and MMP-9. Furthermore, adenovirus-mediated siRNA targetting ezrin inhibited human osteosarcoma MG-63 cell viability, growth, invasion, and migration, and promoted apoptosis. Our study demonstrates that adenovirus-mediated siRNA targetting ezrin can induce apoptosis and inhibit the proliferation, migration, and invasion of human osteosarcoma MG-63 cells.

Decreased local and systemic levels of sFRP3 protein in osteosarcoma patients

Osteosarcoma is a malignant bone tumor that occurs mainly in children and adolescents. Because Wnt signaling has been implicated in the pathogenesis of osteosarcoma, we have investigated the circulating and local levels of the Wnt antagonist protein, Secreted Frizzled Related Protein (sFRP) 3, in osteosarcoma patients. Enzyme linked immunosorbent assay (ELISA) analysis of 67 osteosarcoma and age-matched non-diseased control sera showed that sFPR3 protein levels were significantly lower in osteosarcoma than in normal. Analysis of tumor and adjacent normal tissues (9 pairs) from osteosarcoma patients showed a decrease in sFRP3 expression in 5 out of 9 tumor samples compared to normal tissues. Furthermore, immunohistochemical analysis of tissue microarray revealed a significant decrease in sFRP3 levels in tumor compared to normal bone. RNA sequencing analysis in osteosarcoma cells shows suppression of sFRP3 and concomitant expression of multiple Wnt family members mediating canonical or non-canonical Wnt signaling. Taken together, our findings show that the systemic and local levels of sFRP3 protein are downregulated in osteosarcoma and sFRP3 levels could be explored further in the diagnosis and the care of osteosarcoma patients.

Prognostic Implication of Immunohistochemical Runx2 Expression in Osteosarcoma

Aims and background

Osteosarcoma is the most common primary bone malignancy. Many genetic markers have proven prognostic value in osteosarcoma and studies are under way to determine their potential application as specific therapeutic targets. Runx2, Indian hedgehog (IHH), and Sox9 are proteins that play major roles in bone formation and tumorigenesis. We studied the protein expression of Runx2, IHH, and Sox9 in osteosarcoma and correlated their expression with clinicopathological variables. We also studied the prognostic value of the expression of these three genes in osteosarcoma.

Methods and study design

We produced 48 formalin-fixed, paraffin-embedded tissue microarrays containing osteosarcoma tissue cores for immunohistochemical staining of Runx2, IHH and Sox9. We evaluated the expression of each gene by immunohistochemical staining and analyzed the relationship between expression and clinicopathological parameters.

Results

High expression of Runx2 was significantly related to metastasis (P = 0.015). High expression of Runx2 indicated a trend toward a poor survival rate (P = 0.056). High expression of IHH and Sox9 were not related to any clinicopathological parameters.

Conclusions

High expression of Runx2 was significantly related to tumor metastasis in osteosarcoma. Our results suggest that overexpression of Runx2 might be a useful prognostic marker in osteosarcoma cases.

The Prognostic Role of Ezrin and HER2/neu Expression in Osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor in Egypt. Ezrin is involved in cell adhesion to the extracellular matrix and in cell-cell interactions facilitating metastasis. HER2/neu is overexpressed in breast cancer and other types of cancer. This study aimed to assess the expression of ezrin and HER2/neu in 57 primary osteosarcoma cases and to correlate their expression with the available clinicopathologic parameters and the overall, metastasis-free and event-free survival. Both ezrin and HER2/neu were not expressed in the normal bone and they were upregulated in 82.5% and 71.9% of osteosarcoma, respectively. Positive ezrin expression was significantly associated with young age (below 25 y) (P=0.01), high grade (P=0.001), and short survival time (P=0.0001). Positive HER2/neu expression was significantly associated with high-grade osteosarcoma (P=0.04). Membranous HER2/neu expression was the only factor that showed significant impact on metastasis-free (P=0.002) and event-free survival (P=0.002). Ezrin was significantly correlated with HER2/neu expression (P=0.02). Advanced stage (P=0.0001), metastasis (P=0.0001), and recurrence (P=0.01) were the factors affecting the overall survival of osteosarcoma patients. Ezrin and HER2/neu are overexpressed and coexpressed in osteosarcoma with adverse prognostic features such as high grade. Membranous pattern of HER2/neu seems to be more important than the cytoplasmic pattern because of its impact on metastasis-free and event-free survival. Therefore, ezrin and HER2/neu could be potential prognostic markers and treatment targets for osteosarcoma.

MicroRNA-150 upregulation reduces osteosarcoma cell invasion and metastasis by downregulating Ezrin

The present study aimed to investigate the effect of microRNA-150 (miRNA/miR-150) in osteosarcoma (OS) cell invasion and metastasis by the regulation of Ezrin. To compare the differences in the expression of miR-150 and Ezrin, cell models of OS metastasis were established by exogenous transfection of miR-150 on the basis of different expression levels of miR-150. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to estimate these expression levels. Ezrin expression was detected by western blot assay. Methylthiazolyldiphenyl-tetrazolium bromide assay was performed to determine cells proliferation. Cell invasion and migration were measured in vitro by Transwell migration assays. Detection of apoptosis adopted flow cytometry. The results of RT-qPCR showed that the miR-150 expression in OS F5M2 cells was significantly increased following exogenous transfection of miR-150 mimics, and the expression of miR-150 was positively correlated with the concentration of the miR-150 mimics. Western blot assay indicated that the Ezrin expression in the F5M2 cells was decreased with the exogenous overexpression of miR-150. Additionally, Transwell assays revealed that the overexpression of miR-150 significantly suppressed the invasion and metastasis ability of the F5M2 cells. miR-150 upregulation may reduce OS cell invasion and metastasis by downregulating the expression of Ezrin.

The clinical significance of changes in ezrin expression in osteosarcoma of children and young adults

Ezrin is a protein that functions as a cross-linker between actin cytoskeleton and plasma membrane. Its clinical role in osteosarcoma is unclear. The aim of this study was to investigate, in osteosarcoma, the prognostic value of ezrin expression at biopsy and changes in expression levels after preoperative chemotherapy. Thirty-eight newly diagnosed osteosarcoma patients aged 6-23 years were included. At diagnosis, 20 patients had localized disease, the others had distant metastases. Median follow-up was 75 months (range 13-135). Ezrin expression was assessed immunohistochemically in biopsy tissue and primary tumour specimens resected after chemotherapy. The influence on survival of changes in ezrin expression after chemotherapy was analysed. Ezrin expression was significantly higher after preoperative chemotherapy and changes compared to biopsy tissue were significantly lower in patients with early progression than in patients with relapse or no further evidence of disease (p = 0.006 and p = 0.002, respectively). Similarly, ezrin expression was higher after preoperative chemotherapy and exhibited less change in expression in deceased patients compared to patients surviving more than 5 years (both p = 0.001). Ezrin expression at biopsy was significantly associated with both histopathological aggressiveness (p < 0.001) and tumour size (p = 0.037). The results of this study provide evidence that changes in overexpression of ezrin due to preoperative chemotherapy could be a useful predictive and prognostic marker in patients with osteosarcoma.

Ezrin Binds to DEAD-Box RNA Helicase DDX3 and Regulates Its Function and Protein Level

Ezrin is a key regulator of cancer metastasis that links the extracellular matrix to the actin cytoskeleton and regulates cell morphology and motility. We discovered a small-molecule inhibitor, NSC305787, that directly binds to ezrin and inhibits its function. In this study, we used a nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS-MS)-based proteomic approach to identify ezrin-interacting proteins that are competed away by NSC305787. A large number of the proteins that interact with ezrin were implicated in protein translation and stress granule dynamics. We validated direct interaction between ezrin and the RNA helicase DDX3, and NSC305787 blocked this interaction. Downregulation or long-term pharmacological inhibition of ezrin led to reduced DDX3 protein levels without changes in DDX3 mRNA. Ectopic overexpression of ezrin in low-ezrin-expressing osteosarcoma cells caused a notable increase in DDX3 protein levels. Ezrin inhibited the RNA helicase activity of DDX3 but increased its ATPase activity. Our data suggest that ezrin controls the translation of mRNAs preferentially with a structured 5' untranslated region, at least in part, by sustaining the protein level of DDX3 and/or regulating its function. Therefore, our findings suggest a novel function for ezrin in regulation of gene translation that is distinct from its canonical role as a cytoskeletal scaffold at the cell membrane.

Alteration of WWOX in human cancer: a clinical view

WWOX gene is located in FRA16D, the highly affected chromosomal fragile site. Its tumor suppressor activity has been proposed on a basis of numerous genomic alterations reported in chromosome 16q23.3-24.1 locus. WWOX is affected in many cancers, showing as high as 80% loss of heterozygosity in breast tumors. Unlike most tumor suppressors impairing of both alleles of WWOX is very rare. Despite cellular and animal models information on a WWOX role in cancer tissue is limited and sometimes confusing. This review summarizes information on WWOX in human tumors.

Clinicopathologic characteristics of synchronous primary thyroid cancer detected by initial staging 18F-FDG PET-CT examination in patients with underlying malignancy

BACKGROUND

The objective of this study was to define clinicopathologic characteristics in concurrent primary thyroid cancer detected by initial (18)fluorine-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG PET-CT) scanning in patients with underlying malignancy.

PATIENTS AND METHODS

Among 155 patients with known underlying malignancy and with focal FDG uptake in the thyroid, 25 patients (22 females; mean age ± SD 54.4 ± 11.2 years; age range 27-70 years) who were confirmed as having papillary thyroid cancer (PTC; synchronous thyroid cancer) by cytological examination were included. Another 25 patients (24 females; mean age ± SD, 48.8 ± 12.7 years) with focal uptake in preoperative (18)F-FDG PET-CT due to PTC and no history of other malignancy (primary thyroid cancer) were also included. Immunohistochemical studies were performed for glucose transporter-1 (GLUT-1) and vascular endothelial growth factor (VEGF).

RESULTS

GLUT-1 expression was significantly lower in synchronous thyroid cancer (7 of 25 patients, 28%) compared with primary thyroid carcinoma (15 of 25 patients, 60%; p = 0.045). However, age and tumor size of synchronous thyroid cancer were not significantly different from the patients with primary thyroid carcinomas. There was no significant difference in VEGF expression, maximal standardized uptake values, extrathyroidal extension, lymph node metastasis, advanced stage, and multifocality between both thyroid cancer groups.

CONCLUSION

Clinicopathologic characteristics of synchronous thyroid cancer in patients with underlying malignancy were not different from those of patients with primary thyroid cancers except for GLUT-1 expression.

The Prognostic Role of Ezrin Immunoexpression in Osteosarcoma: A Meta-Analysis of Published Data

Background

The significance of ezrin immunoexpression and prognosis for osteosarcoma is still controversial. The aim was to provide a meta-analysis for ezrin immunoexpression and prognostic features of osteosarcoma patients.

Methods

A detailed search was made in MEDLINE, EMBASE and the Web of Knowledge for relevant original articles published in English; methodological quality of the included studies was also assessed. Two reviewers extracted data independently. Studies were pooled and summary hazard ratios (HRs) and odds ratio (ORs) with corresponding confidence intervals (CIs) were calculated.

Results

Final analysis of 318 patients from 5 eligible studies was performed. Combined HR of ezrin immunohistochemical staining suggested that positive immunoexpression had an unfavorable impact on osteosarcoma patients' overall survival (n = 223 in 4 studies; HR = 4.79; 95% CI: 1.50–15.30; P = 0.008) but not on event-free survival (n = 202 in 3 studies; HR = 1.59; 95% CI: 0.61–4.15; P = 0. 0.342). Combined OR of ezrin immunohistochemical staining indicated that positive immunoexpression was associated with recurrence (n = 134 in 2 studies; OR = 3.79; 95% CI: 1.49–9.64; P = 0.005) but not with serum ALP level (n = 160 in 2 studies; OR = 2.16; 95% CI: 0.09–52.50; P = 0.637) and histological response to neoadjuvant chemotherapy(n = 260 in 4 studies; OR = 0.87; 95% CI: 0.37–2.03; P = 0.740).

Conclusions

The results of this meta-analysis suggest that ezrin positive immunoexpression confers a higher risk of recurrence and a worse survival in osteosarcoma patients. Large prospective studies are needed to provide solid data to investigate the precise prognostic significance of ezrin.

CD99 suppresses osteosarcoma cell migration through inhibition of ROCK2 activity

CD99, a transmembrane protein encoded by MIC2 gene is involved in multiple cellular events including cell adhesion and migration, apoptosis, cell differentiation and regulation of protein trafficking either in physiological or pathological conditions. In osteosarcoma, CD99 is expressed at low levels and functions as a tumour suppressor. The full-length protein (CD99wt) and the short-form harbouring a deletion in the intracytoplasmic domain (CD99sh) have been associated with distinct functional outcomes with respect to tumour malignancy. In this study, we especially evaluated modulation of cell-cell contacts, reorganisation of the actin cytoskeleton and modulation of signalling pathways by comparing osteosarcoma cells characterised by different metastasis capabilities and CD99 expression, to identify molecular mechanisms responsible for metastasis. Our data indicate that forced expression of CD99wt induces recruitment of N-cadherin and β-catenin to adherens junctions. In addition, transfection of CD99wt inhibits the expression of several molecules crucial to the remodelling of the actin cytoskeleton, such as ACTR2, ARPC1A, Rho-associated, coiled-coil containing protein kinase 2 (ROCK2) as well as ezrin, an ezrin/radixin/moesin family member that has been clearly associated with tumour progression and metastatic spread in osteosarcoma. Functional studies point to ROCK2 as a crucial intracellular mediator regulating osteosarcoma migration. By maintaining c-Src in an inactive conformation, CD99wt inhibits ROCK2 signalling and this leads to ezrin decrease at cell membrane while N-cadherin and β-catenin translocate to the plasma membrane and function as main molecular bridges for actin cytoskeleton. Taken together, we propose that the re-expression of CD99wt, which is generally present in osteoblasts but lost in osteosarcoma, through inhibition of c-Src and ROCK2 activity, manages to increase contact strength and reactivate stop-migration signals that counteract the otherwise dominant promigratory action of ezrin in osteosarcoma cells.

Silence of ezrin modifies migration and actin cytoskeleton rearrangements and enhances chemosensitivity of lung cancer cells in vitro

Ezrin, primarily acts as a linker between the plasma membrane and the cytoskeleton, is involved in many cellular functions, including regulation of actin cytoskeleton, control of cell shape, adhesion, motility, and modulation of signaling pathways. Although ezrin is now recognized as a key component in tumor metastasis, its roles and the underlying mechanisms remain unclear. In the present study, we chose highly metastatic human lung carcinoma 95D cells, which highly express the ezrin proteins, as a model to examine the functional roles of ezrin in tumor suppression. An ezrin-silenced 95D cell line was established using lentivirus-mediated short hairpin RNA method. CCK-8 assay and soft agar assay analysis showed that downregulation of ezrin significantly suppressed the tumorigenicity and proliferation of 95D cells in vitro. cell migration and invasion studies showed that ezrin-specific deficiency in the cells caused the substantial reduction of the cell migration and invasion. In parallel, it also induced rearrangements of the actin cytoskeleton. Flow cytometry assay showed that changes in the ezrin protein level significantly affected the cell cycle distribution and eventual apoptosis. Furthermore, further studies showed that ezrin regulated the expression level of E-cadherin and CD44, which are key molecules involved in cell growth, migration, and invasion. Meanwhile, the suppression of ezrin expression also sensitized cells to antitumor drugs. Altogether, our results demonstrated that ezrin played an important role in the tumorigenicity and metastasis of lung cancer cells, which will benefit the development of therapeutic strategy for lung cancer.

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.

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.

Discovery of biomarkers for osteosarcoma by proteomics approaches

Osteosarcomas are the most common malignant bone tumors, and the identification of useful tumor biomarkers and target proteins is required to predict the clinical outcome of patients and therapeutic response as well as to develop novel therapeutic strategies. Global protein expression studies, namely, proteomic studies, can offer important clues to understanding the tumor biology that cannot be obtained by other approaches. These studies, such as two-dimensional gel electrophoresis and mass spectrometry, have provided protein expression profiles of osteosarcoma that can be used to develop novel diagnostic and therapeutic biomarkers, as well as to understand biology of tumor progression and malignancy. In this paper, a brief description of the methodology will be provided followed by a few examples of the recent proteomic studies that have generated new information regarding osteosarcomas.

Low-grade central osteosarcoma: a difficult condition to diagnose

Low-grade central osteosarcoma (LGCO) is a rare variant of osteosarcoma which is difficult to diagnose. If not treated appropriately, the tumour can recur with higher-grade disease. We reviewed our experience of this condition to try and identify factors that could improve both diagnosis and outcome. 18 patients out of 1540 osteosarcoma cases (over 25 years) had LGCO (1.2%). Only 11 patients (61%) were direct primary referrals. Almost 40% (7 of 18) cases were referred after treatment elsewhere when the diagnosis had not been made initially and all presented with local recurrence. Of the 11 who presented primarily, the first biopsy was diagnostic in only 6 (55%) cases. Of the remaining cases, up to three separate biopsies were required before a definitive diagnosis was made. Overall survivorship at 5 years was 90%. 17 patients were treated with limb salvage procedures, and one patient had an amputation. The diagnosis of LGCO remains challenging due to the relatively nonspecific radiological and histological findings. Since treatment of LGCO is so different to a benign lesion, accurate diagnosis is essential. Any difficult or nondiagnostic biopsies of solitary bone lesions should be referred to specialist tumour units for a second opinion.

Expression of ezrin, MMP-9, and COX-2 in 50 chordoma specimens: a clinical and immunohistochemical analysis

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the immunohistochemical expression profile of ezrin, matrix metalloproteinase-9 (MMP-9), and cyclooxygenase-2 (COX)-2 in chordomas.

SUMMARY OF BACKGROUND DATA

Ezrin, MMP-9, and COX-2 are expressed in different solid tumors, including chordomas. This study investigates the immunohistochemical expression of the aforementioned biomarkers and the clinical outcome in regard to immunohistochemistry, tumor volume, and localization.

METHODS

Fifty brachyury-verified chordoma specimens of 34 primary and 16 recurrent tumors of 44 patients were tested for ezrin, MMP-9, and COX-2 as possible therapeutical targets by immunohistochemistry. The clinical evaluation concentrated on tumor location, volume, and age-related data.

RESULTS

Ezrin expression was detected in 33 of 34 primary chordomas and in 16 of 16 recurrent cases. The primary chordomas located in the sacrum and the spine demonstrated a significantly higher percentage of positively stained tumor cells (P = 0.034) than the skull-based chordomas. An expression of MMP-9 and COX-2 was observed in 33 of 34 primary chordomas and in 16 of 16 recurrences, and in 13 of 34 primary chordomas and in 11 of 16 recurrences, respectively. Patients' survival was significantly influenced by age (P = 0.01), tumor location (P = 0.029), and tumor volume (P = 0.002). A significant positive correlation between tumor volume and the anatomic distance of the chordoma from the skull was calculated (P = 0.00002).

CONCLUSION

En bloc resection with tumor-free margins is seldom feasible, particularly in the sacrum. Intralesional excisions mostly end in early local recurrence; therefore, the demand for further treatment options is frequently posed. The marked trend of the investigated biomarkers of this study may build a starting point for further investigations as molecular targets for future adjuvant therapies in chordomas. Future multicenter studies on larger patients' series are necessary to elucidate these preliminary data and to test new treatment options for patients with chordomas.

Cyr61 expression in osteosarcoma indicates poor prognosis and promotes intratibial growth and lung metastasis in mice

Osteosarcoma is the most frequent primary malignant bone tumor in children and adolescents with a high propensity for lung metastasis, the major cause of disease-related death. Reliable outcome-predictive markers and targets for osteosarcoma metastasis-suppressing drugs are urgently needed for more effective treatment of metastasizing osteosarcoma, which has a current mean 5-year survival rate of approximately 20%. This study investigated the prognostic value and the biological relevance of the extracellular matrix-associated growth factor Cyr61 of the CCN family of secreted proteins in osteosarcoma and metastasis. The prognostic value of Cyr61 was assessed with Kaplan-Meier analyses based on Cyr61 immunostaining of a tissue microarray of osteosarcoma biopsies collected from 60 patients with local or metastatic disease. Effects of Cyr61 overexpression on intratibial tumor growth and lung metastasis of the low metastatic human SaOS-2 osteosarcoma cell line were examined in severe combined immunodeficiency (SCID) mice. Cyr61-provoked signaling was studied in vitro in nonmanipulated SaOS-2 cells. Cyr61 immunostaining of osteosarcoma tissue cores correlated significantly (p = 0.02) with poor patient survival. Mice intratibially injected with Cyr61-overexpressing SaOS-2 cells showed faster tumor growth and an increase in number and outgrowth of lung metastases and consequently significantly (p = 0.0018) shorter survival than mice injected with control SaOS-2 cells. Cyr61-evoked PI-3K/Akt/GSK3β signaling in SaOS-2 cells resulted in a subcellular redistribution of the cell cycle inhibitor p21(Cip1/WAF1). Cyr61 has considerable potential as a novel marker for poor prognosis in osteosarcoma and is an attractive target for primary tumor- and metastases-suppressing drugs.

Small molecule inhibitors of ezrin inhibit the invasive phenotype of osteosarcoma cells

Ezrin is a multifunctional protein that connects the actin cytoskeleton to the extracellular matrix through transmembrane proteins. High ezrin expression is associated with lung metastasis and poor survival in cancer. We screened small molecule libraries for compounds that directly interact with ezrin protein using surface plasmon resonance to identify lead compounds. The secondary functional assays used for lead compound selection included ezrin phosphorylation as measured by immunoprecipitation and in vitro kinase assays, actin binding, chemotaxis, invasion into an endothelial cell monolayer, zebrafish and Xenopus embryonic development, mouse lung organ culture and an in vivo lung metastasis model. Two molecules, NSC305787 and NSC668394, that directly bind to ezrin with low micromolar affinity were selected based on inhibition of ezrin function in multiple assays. They inhibited ezrin phosphorylation, ezrin-actin interaction and ezrin-mediated motility of osteosarcoma (OS) cells in culture. NSC305787 mimicked the ezrin morpholino phenotype, and NSC668394 caused a unique developmental defect consistent with reduced cell motility in zebrafish. Following tail vein injection of OS cells into mice, both molecules inhibited lung metastasis of ezrin-sensitive cells, but not ezrin-resistant cells. The small molecule inhibitors NSC305787 and NSC668394 demonstrate a novel targeted therapy that directly inhibits ezrin protein as an approach to prevent tumor metastasis.

MDM2 and CDK4 immunohistochemistry is a valuable tool in the differential diagnosis of low-grade osteosarcomas and other primary fibro-osseous lesions of the bone

Low-grade osteosarcoma is a rare malignancy that may be subdivided into two main subgroups on the basis of location in relation to the bone cortex, that is, parosteal osteosarcoma and low-grade central osteosarcoma. Their histological appearance is quite similar and characterized by spindle cell stroma with low-to-moderate cellularity and well-differentiated anastomosing bone trabeculae. Low-grade osteosarcomas have a simple genetic profile with supernumerary ring chromosomes comprising amplification of chromosome 12q13-15, including the cyclin-dependent kinase 4 (CDK4) and murine double-minute type 2 (MDM2) gene region. Low-grade osteosarcoma can be confused with fibrous and fibro-osseous lesions such as fibromatosis and fibrous dysplasia on radiological and histological findings. We investigated MDM2-CDK4 immunohistochemical expression in a series of 72 low-grade osteosarcomas and 107 fibrous or fibro-osseous lesions of the bone or paraosseous soft tissue. The MDM2-CDK4 amplification status of low-grade osteosarcoma was also evaluated by comparative genomic hybridization array in 18 cases, and the MDM2 amplification status was evaluated by fluorescence in situ hybridization or quantitative real-time polymerase chain reaction in 31 cases of benign fibrous and fibro-osseous lesions. MDM2-CDK4 immunostaining and MDM2 amplification by fluorescence in situ hybridization or quantitative real-time polymerase chain reaction were investigated in a control group of 23 cases of primary high-grade bone sarcoma, including 20 conventional high-grade osteosarcomas, two pleomorphic spindle cell sarcomas/malignant fibrous histiocytomas and one leiomyosarcoma. The results showed that MDM2 and/or CDK4 immunoreactivity was present in 89% of low-grade osteosarcoma specimens. All benign fibrous and fibro-osseous lesions and the tumors of the control group were negative for MDM2 and CDK4. These results were consistent with the MDM2 and CDK4 amplification results. In conclusion, immunohistochemical expression of MDM2 and CDK4 is specific and provides sensitive markers for the diagnosis of low-grade osteosarcomas, helping to differentiate them from benign fibrous and fibro-osseous lesions, particularly in cases with atypical radio-clinical presentation and/or limited biopsy samples.

Relationship between biological marker expression and fluorine-18 fluorodeoxyglucose uptake in incidentally detected thyroid cancer

The aim of this study was to investigate the underlying mechanisms associated with fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake in an incidentally detected thyroid cancer during nonthyroid cancer evaluation. Among 92 patients (10 men and 82 women; mean age, 56.2 +/- 10.9 years; age range, 26-78 years) with focal thyroid FDG uptake during nonthyroid cancer evaluation, 14 patients with cytologically confirmed papillary thyroid cancer were included. For semiquantitative analysis, the maximal standardized uptake value was calculated. Immunohistochemical studies were performed for hypoxia inducible factor 1 alpha (HIF1alpha), HIF2alpha, glucose transporter 1 (GLUT1), GLUT3, carbonic anhydrase IX (CA-IX), hexokinase type II (HK II), and vascular endothelial growth factor (VEGF). The significant findings of this study were as follows: (1) a lack of HIF1alpha and HIF2alpha expression; (2) low-degree expression of GLUT1 (1 patient), GLUT3 (5 of 14 patients), HK II (3 of 14 patients), and CA-IX (1 patient); and (3) high degree expression of VEGF (all 14 patients). The data presented in this study indicate that F-18 FDG uptake in incidentally detected thyroid cancer was not related to hypoxia-induced upregulation of GLUT1, GLUT3, CA-IX, and HK II. Ki-67 expression was not associated with F-18 FDG uptake. However, all incidentally detected thyroid cancers showed a high degree of expression of VEGF.

Expression change of ezrin as a prognostic factor in primary osteosarcoma

Osteosarcoma is a life-threatening malignancy that most often occurs in teenagers. Ezrin is a cytoskeleton linker protein that is actively involved in the metastatic capacity of cancer cells. In this study, we investigated the expression change of ezrin after preoperative chemotherapy and its prognostic value in patients with primary osteosarcoma. Ezrin mRNA expression level of initial biopsy specimens and resected tumor specimens after preoperative chemotherapy of 25 patients who had primary osteosarcoma with ezrin expression was detected by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) to evaluate the expression change of ezrin. In addition, the prognostic factors and the relationship between the expression change of ezrin and the clinical characteristics were analyzed. Expression change of ezrin was found in 64% of all 25 patients. The expression change of ezrin had good relation with histology (P = 0.037), grade (P = 0.006), chemotherapy response (P = 0.017), and metastasis or recurrence (P = 0.041). The 2-year overall survival and event-free survival were associated with expression change of ezrin (P = 0.001 and P = 0.002, respectively) and response to preoperative chemotherapy (P = 0.001 and P = 0.012, respectively). Our findings suggest that expression change of ezrin is an independent positive prognostic factor in non-metastatic osteosarcoma.

Immunoexpression of Ezrin and CD44 in patients with osteosarcoma

BACKGROUND

Metastasis is an important prognostic factor among patients with osteosarcoma. It has been reported that ezrin is important in enabling metastasis and that CD44 expression leads to functional increases in ezrin activation.

OBJECTIVE

The aim of this study was to correlate ezrin and CD44 expression with prognosis.

SAMPLES AND METHODS

Patients with a diagnosis of osteosarcoma who had been treated at Hospital de Cancer de Barretos, Barretos, SP, Brazil, between 2000 and 2005 were selected from the Hospital Tumor Registry. Fifty-two patients and, among these, 34 surgical biopsy specimens of osteosarcoma before chemotherapy were reviewed by the Pathology Department. Ezrin and CD44H protein expression was evaluated using immunohistochemistry on the initial biopsy for these 34 samples.

RESULTS

Most patients (76%) were ezrin-positive in cytoplasm and membrane (38.2%); 58.9% presented high-intensity staining and 50.0% had high scores. Half of the patients were CD44H-positive, predominantly in cytoplasm (38.2%); 20.6% presented staining in more than 50% of the cells. None of the markers showed associations with any of the clinicopathologic variables studied. Among the ezrin-positive patients, the 5-year survival rate was 12.8%, whereas it was 41.7% among ezrin-negative patients (P=0.121). The interaction between ezrin and poor histologic response among nonmetastatic patients showed an association with relapse-free 5-year survival of 100% versus 12.7% (P=0.042). The overall survival rates for CD44-positive and negative patients were similar (21.5% and 25.3%, respectively) (P=0.676).

CONCLUSIONS

Neither CD44H nor ezrin immunoexpression could predict the prognosis for patients with osteosarcoma in our small sample.

Ezrin promotes invasion and metastasis of pancreatic cancer cells

BACKGROUND

Pancreatic cancer has a high mortality rate because it is usually diagnosed when metastasis have already occurred (microscopic and gross disease). Ezrin plays important roles in cell motility, invasion and tumor progression, and it is especially crucial for metastasis. However, its function in pancreatic cancer remains elusive.

METHODS AND RESULTS

We found that ezrin overexpression promoted cell protrusion, microvillus formation, anchorage-independent growth, motility and invasion in a pancreatic cancer cell line, MiaPaCa-2, whereas ezrin silencing resulted in the opposite effects. Ezrin overexpression also increased the number of metastatic foci (6/8 vs. 1/8) in a spontaneous metastasis nude mouse model. Furthermore, ezrin overexpression activated Erk1/2 in MiaPaCa-2 cells, which might be partially related to the alteration of cell morphology and invasion. Immunohistochemical analysis showed that ezrin was overexpressed in pancreatic ductal adenocarcinoma (PDAC) (91.4%) and precancerous lesions, i.e. the tubular complexes in chronic pancreatitis (CP) and pancreatic intraepithelial neoplasm (PanIN) (85.7% and 97.1%, respectively), compared to normal pancreatic tissues (0%). Ezrin was also expressed in intercalated ducts adjacent to the adenocarcinoma, which has been considered to be the origin of ducts and acini, as well as the starting point of pancreatic ductal carcinoma development.

CONCLUSIONS

We propose that ezrin might play functional roles in modulating morphology, growth, motility and invasion of pancreatic cancer cells, and that the Erk1/2 pathway may be involved in these roles. Moreover, ezrin may participate in the early events of PDAC development and may promote its progression to the advanced stage.

Clinical value of ezrin expression in primary osteosarcoma

PURPOSE

Ezrin is a membrane cytoskeletal linker protein and it is known to be associated with metastasis of primary osteosarcoma. The aim of this study is to determine the relationship between an ezrin expression and several key clinical parameters and to elucidate its potential prognostic value for patients with osteosarcoma.

MATERIALS AND METHODS

Seventy patients with histologically confirmed osteosarcoma and who had no distant metastasis were enrolled between 1995 and 2005 at Yonsei Cancer Center, Severance Hospital, Korea. The clinical parameters were retrospectively reviewed and immunohistochemical staining (IHC) for ezrin was performed using the surgically resected specimens.

RESULTS

Of the 70 tumor specimens, 39 (55.7%) revealed an ezrin expression. More of an osteoblastic histology and an elevated initial ALP level were observed in the ezrin positive patients than in the ezrin negative patients (p=0.008 and 0.001, respectively). The proportion of patients who favorably responded to neoadjuvant chemotherapy (≥or=90% necrosis) was significantly higher in the group of ezrin positive patients than that in the group of ezrin negative patient (72.2% vs 45.2%, respectively, p=0.024). The ezrin positive patients showed more frequent recurrence than did the ezrin negative patients (64.1% vs 35.5%, respectively, p=0.017). The patients with an ezrin expression also demonstrated poorer survival than did those patients without ezrin expression (5-year EFS: 31.7% vs 61.3%, respectively, p=0.023, 5-year OS: 53.4% vs 71.0%, respectively, p=0.022). When comparing EFS according to both an ezrin expression and chemoresponsiveness, there were trends that the ezrin negative/chemoresponsive group showed the best 5-year EFS (71.4%), followed by the ezrin negative/chemoresistant group (52.9%), the ezrin positive/chemoresponsive group (38.1%) and the ezrin positive/chemoresistant group (13.6%). These trends were statistically significant (p=0.036).

CONCLUSION

The expression of ezrin by IHC staining was found in 55.7% of the patients with metastasis-free osteosarcoma. Immunoreactivity to ezrin is a negative prognostic factor for survival for the patients suffering with osteosarcoma. Identifying an ezrin expression might offer a valuable piece of information when treating patients with primary osteosarcoma.

Orphan receptor tyrosine kinase ROR2 as a potential therapeutic target for osteosarcoma

Osteosarcoma is the most prevalent bone malignant tumor in children and adolescents, and displays heterogeneous histology and high propensity for distant metastasis. Although adjuvant chemotherapy remarkably improved treatment outcome over the past few decades, prognosis for osteosarcoma patients with pulmonary metastasis is still unsatisfactory. To identify novel therapeutic targets for osteosarcoma, we investigated the gene expression profile of osteosarcomas by cDNA microarray analysis and found transactivation of receptor tyrosine kinase-like orphan receptor 2 (ROR2) expression in the majority of osteosarcoma samples. Treatment of osteosarcoma cell lines with siRNA against ROR2 significantly inhibited cell proliferation and migration. We also identified wingless-type MMTV integration site family, member 5B (WNT5B) as a putative ROR2 ligand and that the physiological interaction of WNT5B and ROR2 could enhance cell migration, indicating the possible roles of ROR2 and WNT5B in the metastatic property of osteosarcoma cells. Taken together, our findings revealed that the WNT5B/ROR2 signaling pathway is a promising therapeutic target for osteosarcoma.

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.

Expression of ezrin and metastatic tumor antigen in osteosarcomas of the jaw

AIMS AND BACKGROUND

Ezrin is a membrane-cytoskeleton linker protein involved in regulation of the growth and metastatic behavior of cancer cells. Metastatic tumor antigen (MTA) is a potential metastasis-associated protein. The objective of this study was to evaluate the expression of ezrin and MTA and their correlation with clinicopathological features in osteosarcomas of the jaw.

METHODS

We analyzed ezrin and MTA protein levels by immunohistochemistry in 31 osteosarcomas of the jaw.

RESULTS

The mean age at diagnosis was 39 years and half of the patients were male. The mandible (n = 19) was more frequently involved than the maxilla (n = 12). The predominant histological type was chondroblastic (58.1%) and 24 patients (77.4%) were classified as having a high grade of malignancy. Immunoreactivity for ezrin was identified in 6 of 31 cases (19.4%), while 77.4% displayed expression of MTA. All ezrin-positive patients had high-grade tumors. The high-grade tumors (n = 24) had a higher rate of MTA expression (42.9% vs 87.5%). Expression of ezrin and MTA was not significantly different according to age, sex, tumor site, histological type, and tumor ploidy. Follow-up information was available for 13 patients, with a mean follow-up time of 26.7 months (range, 6-48 months). At the time of last follow-up, 5 (38.5%) patients had died of disease and 8 patients (61.5%) were alive with no evidence of disease. Expression of ezrin and MTA was not significantly different according to the follow-up data.

CONCLUSIONS

In our study, high-grade tumors had a higher rate of ezrin and MTA expression. This expression pattern indicates that ezrin and MTA positivity can be additional prognostic markers in osteosarcoma of the jaw.

Biomarkers in Osteosarcoma

Osteosarcoma is the most common primary tumor of bone and accounts for approximately 19% of all malignant tumors of bone. It is the third most common malignant tumor in teenagers. More than twenty years ago, the advent of a multidisciplinary approach that combined multi-agent chemotherapy and limb-sparing surgery greatly improved the survival rate of patients with osteosarcoma. Unfortunately, since that time, survival rates have not dramatically improved. To date, the most powerful predictors of outcome have remained the ability to detect metastatic disease at diagnosis and the histopathologic response of the tumor to preoperative chemotherapy. Presently, 80% of patients who do not have distant metastases at initial diagnosis will become long-term survivors. Unfortunately, this means that approximately 20% of patients who do not present with metastases at diagnosis will not survive. This group of patients appears to be resistant to current treatment as attempts to intensify therapy after surgery for patients with a poor histopathologic response has not significantly improved survival rates. It is these patients that are in the greatest need of additional clinically relevant markers for prognosis and who can be most helped by molecular analysis. While steady progress has been made in the identification of genetic alterations in osteosarcoma, no individual molecular marker has thus far been demonstrated to have a better prognostic significance in the treatment of osteosarcomas than the current clinical markers. Thus there is clearly a need to employ new comprehensive analysis technologies to develop significantly more informative classification systems and to identify new therapeutic targets.

Prognostic value of tumor microinvasion and metalloproteinases expression in intracranial pediatric ependymomas

Ependymomas are common pediatric intracranial neoplasms that often appear well circumscribed on imaging but may recur when they are treated by surgical resection alone. The current World Health Organization histological grading system does not accurately predict clinical behavior. The aim of this study was to identify histological and immunohistochemical features that correlate with clinical course in patients with ependymomas treated by gross total resection. We analyzed 41 pediatric ependymomas for microinvasion and correlated immunostaining for the metalloproteinase (MMP)-2 and MMP14 and for ezrin and bcl-2 with clinical outcome. Gross total resection had a significantly positive effect on overall survival and progression-free survival. In 28 patients who underwent gross total resection, microinvasion correlated with poor overall survival (p = 0.003) and progression-free survival (p = 0.03). Gross totally resected tumors with high expression of MMP2 and MMP14 had significantly shorter overall survival. Ezrin staining identified tumor cells invading the adjacent white matter that were not identified by routine stains, but Ezrin staining and bcl-2 staining did not provide strong prognostic correlations. The data indicate that tumor microinvasion into adjacent brain and tumor expression of MMP2 and MMP14 predict both overall and progression-free survival in pediatric ependymomas, and these are useful prognostic markers that may help stratify patients for adjuvant therapies.

Prognostic significance of immunohistochemical expression of ezrin in non-metastatic high-grade osteosarcoma

BACKGROUND

Ezrin is a membrane-cytoskeleton linker protein involved in regulating growth and metastatic behaviour of cancer cells. The study evaluated ezrin expression and its prognostic value in patients with non-metastatic osteosarcoma.

PROCEDURES

Ezrin expression and pattern of staining (cytoplasmic or membraneous and cytoplasmic) were assessed using immunohistochemistry on slides from tumour biopsy. We studied 95 patients (median 16 years, range: 4-39 years) with primary non-metastatic osteosarcoma of the extremity treated by neoadjuvant chemotherapy based on methotrexate, cisplatin, doxorubicin and ifosfamide.

RESULTS

Seventy-six patients (80%) showed ezrin immunoreactivity: in cytoplasm (37, 47%) and in cytoplasm and membrane (42, 53%) of tumour cells. Immunohistochemical staining score was: 1+ (16, 24%), 2+ (10, 13%), 3+ (17, 21.5%) and 4+ (36, 45.5%). Ezrin and score expression were not related to gender, site, alkaline phosphatase (AP), LDH serum levels, chemotherapy-induced tumour necrosis or patient outcome. A significant association was seen between expression pattern and prognosis. The 3-year probability of disease-free survival was 80% for patients with only cytoplasmic immunostaining and 54% for patients with cytoplasmic and membranous immunostaining (P < 0.02).

CONCLUSION

Ezrin immunoreactivity can be detected in the majority of patients with non-metastatic osteosarcoma of the extremity. The pattern of ezrin staining can identify patients with different risks of relapse. In patients who only have ezrin cytoplasmic expression, a probability of EFS >80% at 5 years can be expected. These results suggest further investigations to define the relation between expression pattern, ezrin functional status and outcome in patients with non-metastatic osteosarcoma.

A review of clinical and molecular prognostic factors in osteosarcoma

Traditional prognostic determinants in osteosarcoma have included demographics (age, sex), tumour size, site, stage, and the response to chemotherapy. Many of these are determined using varying techniques and units of measurement, which can make comparison between studies difficult. The absence of survival difference between limb sparing surgery and amputation has been repeatedly demonstrated in primary disease, and even in the setting of pathological fracture. On the other hand, there is still some controversy over the existence of increased local recurrence for limb-sparing surgery, and the implications of this. Commonly used prognostic determinants such as metastases, and response to chemotherapy enable a high degree of prognostic accuracy but usually at a late stage in the course of disease. Leading on from this, there is a need to uncover molecular pathways with specific influence over osteosarcoma progression to facilitate earlier treatment changes. Some important pathways are already being defined, for example the association of CXCR4 with metastases on presentation, the likelihood of doxorubicin resistance with positive P-glycoprotein, and the reduced survival prediction of over expressed survivin. It is anticipated that the future of osteosarcoma treatment will involve treatment tailored to the molecular profile of tumours at diagnosis, adjuvant therapy directed towards dysfunctional molecular pathways rather than the use of cytotoxics, and a more standardised approach to the measurement of clinical prognostic factors.

Ezrin and alpha-smooth muscle actin are immunohistochemical prognostic markers in conventional osteosarcomas

Ezrin is a cytoskeleton linker protein that is actively involved in the metastatic process of cancer cells. We have searched for a prognostic value of ezrin and some of its partners: alpha-smooth muscle actin and CD44H in 37 patients with an osteosarcoma. Automate immunohistochemistry (IHC) with anti-ezrin, alpha-smooth muscle actin and CD44H antibodies was performed in 66 specimens: 37 biopsies before chemotherapy, 16 resected tumours of "poor" responders and 13 metastases. The messenger RNA (mRNA) levels of ezrin of 13 frozen biopsies and 4 metastases were evaluated by real-time quantitative reverse transcriptase polymerase chain reaction (RT-PCR). All results were correlated to the following clinical data. Ezrin expression by IHC was found in 62% of 37 biopsies in the different histological subtypes. A good correlation was found between positive or negative samples by IHC and mRNA levels. Ezrin expression was recorded in 84.5% of metastastic samples. The mean expression of ezrin was higher in metastases than biopsies (p = 0.024). In multivariate analysis, ezrin was an independent prognostic marker for event-free survival and overall survival (OS) with p < 0.001 and p = 0.003, respectively, and alpha-smooth muscle actin for OS only (p = 0.024). Our findings suggest that ezrin and alpha-smooth muscle actin are predictive IHC prognostic markers for patients with an osteosarcoma.