Evaluation of eIF4E expression in an osteosarcoma-specific tissue microarray

Cracking the code: Deciphering the role of the tumor microenvironment in osteosarcoma metastasis

Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. It is characterized by a rapid progression, poor prognosis, and early pulmonary metastasis. Over the past 30 years, approximately 85% of patients with osteosarcoma have experienced metastasis. The five-year survival of patients with lung metastasis during the early stages of treatment is less than 20%. The tumor microenvironment (TME) not only provides conditions for tumor cell growth but also releases a variety of substances that can promote the metastasis of tumor cells to other tissues and organs. Currently, there is limited research on the role of the TME in osteosarcoma metastasis. Therefore, to explore methods for regulating osteosarcoma metastasis, further investigations must be conducted from the perspective of the TME. This will help to identify new potential biomarkers for predicting osteosarcoma metastasis and assist in the discovery of new drugs that target regulatory mechanisms for clinical diagnosis and treatment. This paper reviews the research progress on the mechanism of osteosarcoma metastasis based on TME theory, which will provide guidance for the clinical treatment of osteosarcoma.

MAPK-interacting kinases inhibition by eFT508 overcomes chemoresistance in preclinical model of osteosarcoma

The MAPK-interacting kinases 1 and 2 (MNK1/2) have generated increasing interest as therapeutic targets for many cancers with little known in osteosarcoma. This study evaluated the efficacy of eFT508, a highly selective inhibitor of MNK1/2, as single drug alone and in combination with paclitaxel in preclinical models of osteosarcoma. EFT508 is active against multiple osteosarcoma cell lines via inhibiting growth, survival and migration. It also demonstrates anti-osteosarcoma selectivity with much less toxicity on normal osteoblastic than osteosarcoma cells. Consistent with in vitro findings, eFT508 at non-toxic dose significantly arrested tumor growth in mice throughout the whole duration of treatment. Mechanistically, eEFT508 is highly effective in blocking eIF4E phosphorylation and eIF4E-mediated protein translation. Combination index shows that eFT508 and paclitaxel is synergistic in osteosarcoma cells. Our findings highlight the therapeutic value of MNK1/2 inhibition and suggest eFT508 as a promising candidate for the treatment of osteosarcoma.

p27/Kip1 functions as a tumor suppressor and oncoprotein in osteosarcoma

The p27/kip1 (p27) tumor suppressor inhibits cyclin/cyclin-dependent kinase (CDK) complexes and halts cell cycle progression. p27 further regulates invasion and migration in cancer cells, suggesting p27 also functions as an oncoprotein. Using a human osteosarcoma tissue microarray we identified high expression of cytoplasmic p27 in metastatic tumors. We demonstrated a positive correlation between mRNA and protein expression of p27 and expression of key metastatic markers, vimentin, snail-2, β-catenin and stathmin-1 (STMN1) in patient tumors. Our results show that T198 phosphorylation of p27 controls the interaction between p27 and STMN1 that regulates microtubule stabilization and the invasion and migration of osteosarcoma cells. We found that anti-tumoral activity of gemcitabine and the Wee1 kinase inhibitor AZD1775 in osteosarcoma cells, was dependent on drug sequencing that relied on p27 stabilization. Gemcitabine activated caspase-3 and synergized with AZD1775 through caspase-mediated cleavage of p27, that dissociated from STMN1 and effectively induced apoptosis. Further, blockage of nuclear export of p27 by inhibition of Exportin-1 (XPO1) promoted growth arrest, demonstrating that the biological effects of agents relied on the expression and localization of p27. Together, these data provide a rationale for combining chemotherapy with agents that promote p27 tumor suppressor activity for the treatment of osteosarcoma.

Up-regulation of microRNA-496 suppresses proliferation, invasion, migration and in vivo tumorigenicity of human osteosarcoma cells by targeting eIF4E

Osteosarcoma is an aggressive bone tumor characterized by a high level of genetic instability and recurring DNA deletions and amplifications. This study aims to investigate how microRNA-496 (miR-496) affects proliferation, invasion, and migration of human osteosarcoma (OS) cells and in vivo tumorigenicity by targeting eukaryotic translation initiation factor 4E (eIF4E). Microarray-based gene expression profiling involving OS was used in order to identify differentially expressed genes. After that, the interaction between miR-496 expression and OS patients' survival rate was determined. The expression pattern of miR-496 and eIF4E was determined in OS tissues and cells, and their potential relationship was further analyzed by using the dual luciferase reporter gene assay. With the purpose of identifying the functional role miR-496 in OS, cell proliferation, migration, and invasion were measured in cells treated with miR-496 mimic or inhibitor. A nude mouse model was constructed in order to investigate the regulatory effects of miR-496 on tumor growth in vivo by regulating eIF4E. OS cells exhibited a down-regulated expression of miR-496 and an up-regulated expression of eIF4E. miR-496 expression was positively correlated to OS patients' survival rate. Bioinformatics analysis suggested eIF4E would be a direct target of miR-496, and the expression of eIF4E was inhibited by overexpression of miR-496. miR-496 elevation was found to exert suppressive effects on OS cell proliferation, migration and invasion in vitro and tumor growth in vivo, with the effects being reversed using miR-496 depletion. Altogether, the above findings support a conclusion that miR-496 could work as a tumor suppressor in OS through down-regulation of eIF4E. This study may provide a novel target for treatment of OS.

Inhibitory effect of MSH6 gene silencing in combination with cisplatin on cell proliferation of human osteosarcoma cell line MG63

Osteosarcoma (OS) is one of the most common primary bone malignancies, with the survival rate of patients with OS remaining low. Therefore, we conducted this study to identify the potential role combination of both MSH6 gene silencing and cisplatin (DDP) plays in OS cell proliferation and apoptosis. Microarray-based gene expression profiling was used to identify the differentially expressed genes (DEGs) in patients with OS, as well as microRNAs (miRNAs) that regulate the candidate gene. OS tissues from 67 patients with OS along with normal tissues from 24 amputee patients were collected for detection of the positive expression of mutS homolog 6 (MSH6) protein, mRNA, and protein expressions of c-myc, cyclin D1, l-2, B-cell lymphoma 2 (Bcl-2), Stathmin, proliferating cell nuclear antigen (PCNA), and Bcl-2-associated X (Bax). Moreover, after MSH6 silencing and DDP were treated on the selected human OS cell line MG63 with the highest expression of MSH6, cell viability, cell cycle distribution, and apoptosis were detected. The microarray analysis showed that MSH6 was upregulated in OS chip data. Furthermore, silencing MSH6 combined with DDP reduced expressions of c-myc, cyclin D1, Bcl-2, Stathmin, and PCNA, and elevated Bax expression, whereas inhibiting OS cell viability, impeding cell cycle distribution, and inducing apoptosis. In conclusion, our preliminary results indicated that the combination of MSH6 gene silencing coupled with DDP may have a better effect on the inhibition of OS cell proliferation and promote apoptosis, potentially providing targets for the OS treatment.

Exploring the key genes and pathways of side population cells in human osteosarcoma using gene expression array analysis

BACKGROUND

Human osteosarcoma (OS) is one of the most common primary bone sarcoma, because of early metastasis and few treatment strategies. It has been reported that the tumorigenicity and self-renewal capacity of side population (SP) cells play roles in human OS via regulating of target genes. This study aims to complement the differentially expressed genes (DEGs) that regulated between the SP cells and the non-SP cells from primary human OS and identify their functions and molecular pathways associated with OS.

METHODS

The gene expression profile GSE63390 was downloaded, and bioinformatics analysis was made.

RESULTS

One hundred forty-one DEGs totally were identified. Among them, 72 DEGs (51.06%) were overexpressed, and the remaining 69 DEGs (48.94%) were underexpressed. Gene ontology (GO) and pathway enrichment analysis of target genes were performed. We furthermore identified some relevant core genes using gene-gene interaction network analysis such as EIF4E, FAU, HSPD1, IL-6, and KISS1, which may have a relationship with the development process of OS. We also discovered that EIF4E/mTOR signaling pathway could be a potential research target for therapy and tumorigenesis of OS.

CONCLUSION

This analysis provides a comprehensive understanding of the roles of DEGs coming from SP cells in the development of OS. However, these predictions need further experimental validation in future studies.

Positively selected enhancer elements endow osteosarcoma cells with metastatic competence

Metastasis results from a complex set of traits acquired by tumor cells, distinct from those necessary for tumorigenesis. Here, we investigate the contribution of enhancer elements to the metastatic phenotype of osteosarcoma. Through epigenomic profiling, we identify substantial differences in enhancer activity between primary and metastatic human tumors and between near isogenic pairs of highly lung metastatic and nonmetastatic osteosarcoma cell lines. We term these regions metastatic variant enhancer loci (Met-VELs). Met-VELs drive coordinated waves of gene expression during metastatic colonization of the lung. Met-VELs cluster nonrandomly in the genome, indicating that activity of these enhancers and expression of their associated gene targets are positively selected. As evidence of this causal association, osteosarcoma lung metastasis is inhibited by global interruptions of Met-VEL-associated gene expression via pharmacologic BET inhibition, by knockdown of AP-1 transcription factors that occupy Met-VELs, and by knockdown or functional inhibition of individual genes activated by Met-VELs, such as that encoding coagulation factor III/tissue factor (F3). We further show that genetic deletion of a single Met-VEL at the F3 locus blocks metastatic cell outgrowth in the lung. These findings indicate that Met-VELs and the genes they regulate play a functional role in metastasis and may be suitable targets for antimetastatic therapies.

Icariside II, a natural mTOR inhibitor, disrupts aberrant energy homeostasis via suppressing mTORC1-4E-BP1 axis in sarcoma cells

The aberrant energy homeostasis that characterized by high rate of energy production (glycolysis) and energy consumption (mRNA translation) is associated with the development of cancer. As mammalian target of rapamycin (mTOR) is a critical regulator of aberrant energy homeostasis, it is an attractive target for anti-tumor intervention. The flavonoid compound Icariside II (IS) is a natural mTOR inhibitor derived from Epimedium. Koreanum. Herein, we evaluate the effect of IS on aberrant energy homeostasis. The reduction of glycolysis and mRNA translation in U2OS (osteosarcoma), S180 (fibrosarcoma) and SW1535 (chondrosarcoma) cells observed in our study, indicate that, IS inhibits aberrant energy homeostasis. This inhibition is found to be due to suppression of mammalian target of rapamycin complex 1 (mTORC1)-eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) axis through blocking the assembly of mTORC1. Furthermore, IS inhibits the cap-dependent translation of c-myc through mTORC1-4E-BP1 axis which links the relationship between mRNA translation and glycolysis. Inhibition of aberrant energy homeostasis by IS, contributes to its in vitro and in vivo anti-proliferation activity. These data indicate that IS disrupts aberrant energy homeostasis of sarcoma cells through suppression of mTORC1-4E-BP1 axis, providing a novel mechanism of IS to inhibit cell proliferation in sarcoma cells.

Comparative proteomics reveals the physiological differences between winter tender shoots and spring tender shoots of a novel tea (Camellia sinensis L.) cultivar evergrowing in winter

BACKGROUND

A recently discovered tea [Camellia sinensis (L.) O. Kuntze] cultivar can generate tender shoots in winter. We performed comparative proteomics to analyze the differentially accumulated proteins between winter and spring tender shoots of this clonal cultivar to reveal the physiological basis of its evergrowing character during winter.

RESULTS

We extracted proteins from the winter and spring tender shoots (newly formed two leaves and a bud) of the evergrowing tea cultivar "Dongcha11" respectively. Thirty-three differentially accumulated high-confidence proteins were identified by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF / TOF MS). Among these, 24 proteins had increased abundance while nine showed were decreased abundance in winter tender shoots as compared with the spring tender shoots. We categorized the differentially accumulated proteins into eight critical biological processes based on protein function annotation including photosynthesis, cell structure, protein synthesis & destination, transporters, metabolism of sugars and polysaccharides, secondary metabolism, disease/defense and proteins with unknown functions. Proteins with increased abundance in winter tender shoots were mainly related to the processes of photosynthesis, cytoskeleton and protein synthesis, whereas those with decreased abundance were correlated to metabolism and the secondary metabolism of polyphenolic flavonoids. Biochemical analysis showed that the total contents of soluble sugar and amino acid were higher in winter tender shoots while tea polyphenols were lower as compared with spring tender shoots.

CONCLUSIONS

Our study suggested that the simultaneous increase in the abundance of photosynthesis-related proteins rubisco, plastocyanin, and ATP synthase delta chain, metabolism-related proteins eIF4 and protease subunits, and the cytoskeleton-structure associated proteins phosphatidylinositol transfer protein and profilin may be because of the adaptation of the evergrowing tea cultivar "Dongcha11" to low temperature and light conditions. Histone H4, Histone H2A.1, putative In2.1 protein and protein lin-28 homologs may also regulate the development of winter shoots and their response to adverse conditions.

CD49b inhibits osteogenic differentiation and plays an important role in osteosarcoma progression

Osteosarcoma is a cancer whose cell of origin lies in the differentiation pathway between the mesenchymal stem cell (MSC) and the osteoblast (OB). In this study, we sought to determine if surface markers associated with osteoblastic differentiation are involved in osteosarcoma progression. cDNA expression arrays were performed on MSCs and osteoblasts to identify differentially expressed genes. The specificity of candidate genes for osteoblast differentiation was assessed through time course experiments in differentiation media with confirmation utilizing CD49b transfected MSCs. In addition, CD49b was transfected into osteosarcoma cell lines to determine its impact on cell proliferation, motility, and invasion. Finally, the expression of CD49b was assessed in osteosarcoma patient samples and correlated with survival outcomes. cDNA expression arrays identified a list of genes differentially expressed between MSCs and osteoblasts with a subset of those genes encoding cell surface proteins. Three genes were selected for further analysis, based on qPCR validation, but only CD49b was selective for osteoblastic differentiation. Forced expression of CD49b in MSCs led to delayed osteoblastic differentiation. Down-regulation of CD49b expression in osteosarcoma cell lines resulted in inhibition of their migration and invasion capacity. CD49b expression in osteosarcoma patients was associated with presence of metastases and inferior 5 year overall survival (31.4% vs. 57.4%, p=0.03). Surface proteins involved in osteosarcoma cell differentiation, such as CD49b, have the potential to serve as prognostic biomarkers, and may lead to the identification of new therapeutic targets.

Upregulation of Glucose-Regulated Protein 78 in Metastatic Cancer Cells Is Necessary for Lung Metastasis Progression

Metastasis is the cause of more than 90% of all cancer deaths. Despite this fact, most anticancer therapeutics currently in clinical use have limited efficacy in treating established metastases. Here, we identify the endoplasmic reticulum chaperone protein, glucose-regulated protein 78 (GRP78), as a metastatic dependency in several highly metastatic cancer cell models. We find that GRP78 is consistently upregulated when highly metastatic cancer cells colonize the lung microenvironment and that mitigation of GRP78 upregulation via short hairpin RNA or treatment with the small molecule IT-139, which is currently under clinical investigation for the treatment of primary tumors, inhibits metastatic growth in the lung microenvironment. Inhibition of GRP78 upregulation and an associated reduction in metastatic potential have been shown in four highly metastatic cell line models: three human osteosarcomas and one murine mammary adenocarcinoma. Lastly, we show that downmodulation of GRP78 in highly metastatic cancer cells significantly increases median survival times in our in vivo animal model of experimental metastasis. Collectively, our data indicate that GRP78 is an attractive target for the development of antimetastatic therapies.

Prognostic significance of eukaryotic initiation factor 4E in hepatocellular carcinoma

PURPOSE

Aberrant expression of eukaryotic initiation factor 4E (eIF4E) has been observed in human malignancies. However, its role in hepatocellular carcinoma (HCC) remains to be established. The purpose of this study was to detect eIF4E expression and to evaluate its clinical relevance.

METHODS

The eIF4E expression was studied in ninety HCC and randomly selected thirty-one non-tumor tissues from the same patient cohort, as well as in normal hepatic and HCC cell lines. The relation between its expression and clinicopathological parameters was also analyzed.

RESULTS

eIF4E expression was higher in HCC samples and cell lines compared with that in non-tumor tissues (P < 0.001) and hepatocyte LO2, respectively. eIF4E overexpression was significantly associated with tumor number (P = 0.005) and incomplete encapsulation (P = 0.001). The 5-year overall survival rate and disease-free survival rate for patients with high eIF4E expression were 32.5 and 31.2 %, respectively; and for low eIF4E expression, it was 67.9 and 64.4 %, respectively (P < 0.001). Furthermore, subgroup analysis showed that high eIF4E level predicted poorer overall survival only for incomplete encapsulation (P = 0.001) and cirrhosis (P < 0.001), but not for complete encapsulation (P = 0.804) and non-cirrhosis (P = 0.359). Multivariate analysis revealed that eIF4E overexpression was an independent indicator for both overall survival (hazard ratio, 2.015; P = 0.043) and disease-free survival (hazard ratio, 2.666; P = 0.006).

CONCLUSIONS

eIF4E protein might result in the malignant progression of HCC, and its overexpression may be a powerful prognostic biomarker and therapeutic target for HCC patients.

HHLA2, a member of the B7 family, is expressed in human osteosarcoma and is associated with metastases and worse survival

Over the past four decades there have been minimal improvements in outcomes for patients with osteosarcoma. New targets and novel therapies are needed to improve outcomes for these patients. We sought to evaluate the prevalence and clinical significance of the newest immune checkpoint, HHLA2, in osteosarcoma. HHLA2 protein expression was evaluated in primary tumor specimens and metastatic disease using an osteosarcoma tumor microarray (TMA) (n = 62). The association of HHLA2 with the presence of tumor infiltrating lymphocytes (TILs) and five-year-event-free-survival were examined. HHLA2 was expressed in 68% of osteosarcoma tumors. HHLA2 was expressed in almost all metastatic disease specimens and was more prevalent than in primary specimens without known metastases (93% vs 53%, p = 0.02). TILs were present in 75% of all osteosarcoma specimens. Patients whose tumors were ≥25% or ≥50% HHLA2 positive had significantly worse five-year event-free-survival (33% vs 64%, p = 0.03 and 14% vs 59%, p = 0.02). Overall, we have shown that HHLA2 is expressed in the majority of osteosarcoma tumors and its expression is associated with metastatic disease and poorer survival. Along with previously reported findings that HHLA2 is a T cell co-inhibitor, these results suggest that HHLA2 may be a novel immunosuppressive mechanism within the osteosarcoma tumor microenvironment.

Immune infiltration and PD-L1 expression in the tumor microenvironment are prognostic in osteosarcoma

Osteosarcoma patient survival has remained stagnant for 30 years. Novel therapeutic approaches are needed to improve outcomes. We examined the expression of Programmed Death Ligand 1 (PD-L1) and defined the tumor immune microenvironment to assess the prognostic utility in osteosarcoma. PD-L1 expression in osteosarcoma was examined in two patient cohorts using immunohistochemistry (IHC) (n = 48, n = 59) and expression was validated using quantitative real time PCR (n = 21) and western blotting (n = 9). IHC was used to determine the presence of tumor infiltrating lymphocytes and antigen-presenting cells (APCs) in the tumor. Expression of PD-L1 was correlated with immune cell infiltration and event-free-survival (EFS). The 25% of primary osteosarcoma tumors that express PD-L1 were more likely to contain cells that express PD-1 than PD-L1 negative tumors (91.7% vs 47.2%, p = 0.002). Expression of PD-L1 was significantly associated with the presence of T cells, dendritic cells, and natural killer cells. Although all immune cell types examined were present in osteosarcoma samples, only infiltration by dendritic cells (28.3% vs. 83.9%, p = 0.001) and macrophages (45.5% vs. 84.4%, p = 0.031) were associated with worse five-year-EFS. PD-L1 expression was significantly associated with poorer five-year-EFS (25.0%. vs. 69.4%, p = 0.014). Further studies in osteosarcoma are needed to determine if targeting the PD-L1:PD-1 axis improves survival.

mTOR Inhibition Mitigates Enhanced mRNA Translation Associated with the Metastatic Phenotype of Osteosarcoma Cells In Vivo

PURPOSE

To successfully metastasize, tumor cells must respond appropriately to biological stressors encountered during metastatic progression. We sought to test the hypothesis that enhanced efficiency of mRNA translation during periods of metastatic stress is required for metastatic competence of osteosarcoma and that this metastasis-specific adaptation is amenable to therapeutic intervention.

EXPERIMENTAL DESIGN

We employ novel reporter and proteomic systems that enable tracking of mRNA translation efficiency and output in metastatic osteosarcoma cells as they colonize the lungs. We test the potential to target mRNA translation as an antimetastatic therapeutic strategy through pharmacokinetic studies and preclinical assessment of the prototypic mTOR inhibitor, rapamycin, across multiple models of metastasis.

RESULTS

Metastatic osteosarcoma cells translate mRNA more efficiently than nonmetastatic cells during critical stressful periods of metastatic colonization of the lung. Rapamycin inhibits translational output during periods of metastatic stress, mitigates lung colonization, and prolongs survival. mTOR-inhibiting exposures of rapamycin are achievable in mice using treatment schedules that correspond to human doses well below the MTDs defined in human patients, and as such are very likely to be tolerated over long exposures alone and in combination with other agents.

CONCLUSIONS

Metastatic competence of osteosarcoma cells is dependent on efficient mRNA translation during stressful periods of metastatic progression, and the mTOR inhibitor, rapamycin, can mitigate this translation and inhibit metastasis in vivo Our data suggest that mTOR pathway inhibitors should be reconsidered in the clinic using rationally designed dosing schedules and clinical metrics related to metastatic progression. Clin Cancer Res; 22(24); 6129-41. ©2016 AACR.

Expression of phosphorylated eIF4E-binding protein 1, but not of eIF4E itself, predicts survival in male breast cancer

Background:

Male breast cancer is rare and treatment is based on data from females. High expression/activity of eukaryotic initiation factor 4E (eIF4E) denotes a poor prognosis in female breast cancer, and the eIF4E pathway has been targeted therapeutically. Eukaryotic initiation factor 4E activity in female breast cancer is deregulated by eIF4E overexpression and by phosphorylation of its binding protein, 4E-BP1, which relieves inhibitory association between eIF4E and 4E-BP1. The relevance of the eIF4E pathway in male breast cancer is unknown.

Methods:

We have assessed expression levels of eIF4E, 4E-BP1, 4E-BP2 and phosphorylated 4E-BP1 (p4E-BP1) using immunohistochemistry in a large cohort of male breast cancers (n=337) and have examined correlations with prognostic factors and survival.

Results:

Neither eIF4E expression nor estimated eIF4E activity were associated with prognosis. However, a highly significant correlation was found between p4E-BP1 expression and disease-free survival (DFS), linking any detectable p4E-BP1 with poor survival (univariate log rank P=0.001; multivariate HR 8.8, P=0.0001).

Conclusions:

Our data provide no support for direct therapeutic targeting of eIF4E in male breast cancer, unlike in females. However, as p4E-BP1 gives powerful prognostic insights that are unrelated to eIF4E function, p4E-BP1 may identify male breast cancers potentially suitable for therapies directed at the upstream kinase, mTOR.

A Sleeping Beauty forward genetic screen identifies new genes and pathways driving osteosarcoma development and metastasis

Osteosarcomas are sarcomas of the bone, derived from osteoblasts or their precursors, with a high propensity to metastasize. Osteosarcoma is associated with massive genomic instability, making it problematic to identify driver genes using human tumors or prototypical mouse models, many of which involve loss of Trp53 function. To identify the genes driving osteosarcoma development and metastasis, we performed a Sleeping Beauty (SB) transposon-based forward genetic screen in mice with and without somatic loss of Trp53. Common insertion site (CIS) analysis of 119 primary tumors and 134 metastatic nodules identified 232 sites associated with osteosarcoma development and 43 sites associated with metastasis, respectively. Analysis of CIS-associated genes identified numerous known and new osteosarcoma-associated genes enriched in the ErbB, PI3K-AKT-mTOR and MAPK signaling pathways. Lastly, we identified several oncogenes involved in axon guidance, including Sema4d and Sema6d, which we functionally validated as oncogenes in human osteosarcoma.

Ganglioside GD2 as a therapeutic target for antibody-mediated therapy in patients with osteosarcoma

BACKGROUND

Survival outcomes for patients with osteosarcoma have remained stagnant over the past 30 years. Targeting of ganglioside GD2, a glycosphingolipid on the cell surface of some tumors, with immunotherapy has resulted in improved outcomes for patients with neuroblastoma. In the current study, the expression pattern of GD2 was examined in osteosarcoma.

METHODS

Immunohistochemistry was performed on osteosarcoma samples from patients at the time of initial biopsy, definitive surgery, and disease recurrence. The intensity and location of staining were scored. Cell-based enzyme-linked immunoadsorbent assay was performed on osteosarcoma cell lines to quantitate the level of GD2 expression.

RESULTS

Forty-four osteosarcoma samples were evaluated by immunohistochemistry, including 8 samples from the initial biopsy, 28 samples from the definitive surgery, and 8 samples from the time of disease recurrence. GD2 was expressed on all 44 osteosarcoma samples. Osteosarcoma tissue obtained at the time of disease recurrence demonstrated a higher intensity of staining compared with samples obtained at initial biopsy and definitive surgery (P = .016). The majority of osteosarcoma cell lines expressed GD2 at higher levels than the neuroblastoma cell line BE(2)-C.

CONCLUSIONS

Ganglioside GD2 is highly expressed on osteosarcomas. Clinical trials are needed to assess the efficacy of targeting GD2 in patients with osteosarcoma.

A review of the association between osteosarcoma metastasis and protein translation

The malignant transformation of mesenchymal cells within the bone leads to the development of osteosarcoma (OS), but the genetic underpinnings of these events are not understood. From a clinical perspective, primary tumour management can be achieved successfully in most patients. However, the development of metastasis to the lungs represents the most common cause of death in OS patients. A clearer understanding of metastasis biology is required to improve cancer mortality and improve outcomes. Modelling the genetics, biology and therapy of OS can be accomplished through research involving a number of species. Most notable is the naturally occurring form of OS that develops in dogs. Through a cross-species and comparative approach important questions can be asked within specific and suitable models to advance our understanding of this disease and its common metastatic outcome. A comparative perspective on the problem of OS metastasis that utilizes a cross-species approach may offer unique opportunities to assist in this prioritization and generate new hypotheses related to this important clinical problem.