Molecular biology of the Ewing's sarcoma/primitive neuroectodermal tumor family

Factores de riesgo para los tumores óseos malignos pediátricos

INTRODUCTION

Cancer is the result of the interaction of two kinds of determinants: genetic (endogenous) and environmental (exogenous). In the last few decades, pediatric oncology as a whole has progressed, including knowledge of malignant osseous tumors (MOT). Although advances have been made in diagnostic and therapeutic aspects, little progress has taken place in our knowledge of the risk factors involved in their etiopathogenesis.

OBJECTIVE

This review has three objectives: a) to provide an update on MOT-related risk factors in the child and adult population; b) to disseminate knowledge of the main MOT-related risk factors among our colleagues in order to promote research into these factors, diagnosis and future prevention, and c) to request help from our colleagues in the Environment and Pediatric Cancer research project.

MATERIAL AND METHODS

We performed a systematic review of the literature published in the last 30 years on risk factors implicated in the etiopathogenesis of MOT, using Medline, Cancerlit, Science Citation Index and Embase. The search profiles used were: pediatric/childhood malignant bone tumors, pediatric/ childhood bone cancer/neoplasm, osteosarcoma/bone sarcoma/Ewing's sarcoma and risk factors/etiology/epidemiology. The most interesting articles were selected and the most relevant references contained therein were retrieved.

RESULTS

MOT represent 6-7 % of all pediatric neoplasms. The most frequent types are osteosarcoma (OS) and Ewing's sarcoma (ES), representing 56 % and 34 % respectively. OS-related risk factors are the following: a) previous osseous disease (Paget's disease); b) familial-genetic factors (hereditary retinoblastoma, Li-Fraumeni syndrome, Rothmund-Thompson syndrome, Bloom syndrome, familial OS, Diamond-Blackfan anemia); c) chemical factors (antineoplastic drugs); d) physical factors (ionizing radiation); e) biologic factors; f) parental occupation, and g) other factors (artificial osseous implants and traumatisms). ES-related risk factors are the following: a) ethnic-cultural (Caucasian race); b) genetic factors; c) parental occupation (herbicide, pesticide and fertilizer exposure); d) maternal obstetric history, and e) other factors (parental smoking and inguinal hernia).

CONCLUSIONS

Most causes of MOT are unknown. Based on different levels of scientific evidence, the main factors implicated in the etiopathogenesis of OS are: Paget's disease, hereditary retinoblastoma, Li-Fraumeni syndrome, antineoplastic drugs, and ionizing radiation. The main factors related to ES are: Caucasian race, parental occupation, parental smoking, and surgery for inguinal hernia. The main obstacles to greater knowledge of MOT-related factors are: a) their multiple origin; b) the low prevalence in the population; c) lack of environmental health training in pediatrics, and d) the low public and private investment in this research field.

EWS–ETS oncoproteins: The linchpins of Ewing tumors

Ewing tumors, which comprise Ewing's sarcoma and peripheral primitive neuroectodermal tumors, are highly aggressive and mostly affect children and adolescents. Their molecular signature is a chromosomal translocation leading to the generation of EWS-ETS (or very rarely FUS-ETS) fusion proteins that are capable of transforming cells. These oncoproteins act as aberrant transcription factors due to the fusion of an ETS DNA binding domain to a highly potent EWS (or FUS) transactivation domain. Accordingly, many EWS-ETS target genes have been identified whose dysregulation could contribute to the development of tumor formation. Furthermore, EWS-ETS oncoproteins may impact on RNA splicing or affect other proteins through disturbing their ability to form functional complexes. The molecular knowledge gained so far from studying EWS-ETS oncoproteins has not only broadened our understanding of Ewing tumors but also improved the diagnosis of these highly undifferentiated tumors. In addition, several potential prognostic markers have been uncovered and novel therapies are suggested that may improve the still dismal survival rate of Ewing tumor patients.

Intracranial Ewing sarcoma

The occurrence of primary extraosseous Ewing sarcoma (EES) of the central nervous system (CNS) has only rarely been reported in the literature. It is important to distinguish this entity from the more common central primitive neuroectodermal tumor (PNET) of brain, since the management of these tumors is different from that of EES. We present the clinical, radiologic, and pathologic features of two cases of EES occurring in the brain. The diagnosis was further confirmed by detection of a rearrangement of the FLI1 and/or EWS gene loci in tumors from both patients using fluorescent in situ hybridization (FISH). Although rare, the possibility of EES should be considered particularly when tumors that arise near the meningeal surface of the brain and have the pathologic appearance of a PNET. Demonstration of t(11;22)(q24;q12) by molecular analysis essentially confirms the diagnosis and enables the oncologist to choose appropriate therapy.

Intercellular junctions in Ewing sarcoma/primitive neuroectodermal tumor: additional evidence of epithelial differentiation

Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) has recently been shown to frequently express cytokeratins, suggesting partial epithelial differentiation. Older ultrastructural studies have documented primitive cell-cell junctions in ES/PNET, reportedly resembling poorly formed desmosomes. Recently, paraffin-reactive antibodies have become available to proteins found in a variety of intercellular junctions indicative of epithelial differentiation, including tight junctions, desmosomes and adherens junctions. We examined intercellular junction protein expression in a large number of genetically confirmed ES/PNET. Formalin-fixed, paraffin-embedded sections from 23 primary and seven recurrent or metastatic cases of genetically confirmed ES/PNET were immunostained for claudin-1 and occludin (tight junction structural proteins), zonula occludens-1 (ZO-1, tight junction linker protein), desmoglein 1/2 (desmosomal adherens protein), desmoplakin (desmosomal structural protein) and E-cadherin (epithelial adherens junction protein), using steam heat-induced epitope retrieval and the Dako Envision system. Cases with >5% positive cells were scored as 'positive'. Normal colonic epithelium and skin served as external positive controls. Claudin-1 was expressed by 19 of 30 specimens (63%), ZO-1 was expressed by 15 of 29 specimens (51%), and occludin was expressed by three of 28 specimens (11%). In 28 specimens all three tight junction markers were evaluable. In all, 15 samples (54%) expressed only one tight junction marker, and 10 samples (36%) expressed two tight junction markers. No case expressed all three tight junction markers. Desmoglein was expressed in one of 30 (3%) samples. Desmoplakin was expressed in two of 28 (7%) samples. E-cadherin was negative in all cases. Our data suggest that many of the previously described cell-cell junctions in ES/PNET are poorly formed tight junctions, given the high frequency of claudin-1 and ZO-1 expression. This may underestimate the true frequency of tight junction protein expression in ES/PNET, as there are at least 20 different claudins and other ZO proteins. These tight junctions are almost certainly abnormal, given the absence of occludin expression in most cases. Desmosomal and adherens junction protein expression was rare to absent. Our findings provide additional evidence that ES/PNET frequently show partial epithelial differentiation.

Transactivation of cyclin E gene by EWS-Fli1 and antitumor effects of cyclin dependent kinase inhibitor on Ewing's family tumor cells

Chromosomal translocation t(11; 22)(q24; q12) is detected in approximately 90% of Ewing's family tumors (EFTs) including Ewing's sarcoma and primitive neuroectodermal tumor. This results in the formation of the EWS-Fli1 fusion gene, which produces EWS-Fli1 fusion protein. This chimerical gene product acts as an aberrant transcriptional activator, which may be responsible for the tumorigenesis of EFTs. We have previously reported that cyclin E expression was upregulated in EFT cells and in EWS-Fli1 transformed fibroblastic cells. However, the mechanism of the overexpression of cyclin E by EWS-Fli1 is still unknown. In our study, we investigated the mechanism of transactivation of the cyclin E gene in EFT cells. We found that EWS-Fli1 enhanced the activity of the cyclin E gene promoter partially through E2F binding sites in the promoter. In addition, the basic transcriptional factor, Sp1, might also be involved in the transactivation of the cyclin E gene by EWS-Fli1. To study the biological significance of cyclin E overexpression in EFT cells, we used flavopiridol, a pan-cyclin-dependent kinase (CDK) inhibitor and found that flavopiridol efficiently suppressed the growth of EFT cells in vitro and in vivo by the inhibition of cyclinE/CDK2 kinase activity and the induction of apoptosis. These results suggest that targeting of the cyclin/CDK complex may provide new insight into treatment of EFTs.

Type 1 (11; 22)(q24: q12) translocation is common in Ewing’s sarcoma/ peripheral neuroectodermal tumour in south Indian patients

The Ewing's sarcoma family can present diagnostic difficulties. In the past the basis of diagnosis has been a exclusion. Identification of a specific translocation especially t(11;22) (EWS-FLI 1 fusion gene), which is seen in nearly 85 percent of Ewing's sarcoma cases can help in precise diagnosis. We have carried out a study on twenty patient samples diagnosed to have Ewing's sarcoma/peripheral neuroectodermal tumour (PNET)/small round cell malignant tumour. The study involved RT-PCR analysis for the fusion transcript, followed by sequencing to identify the specific type of fusion. Ninety percent (18/20) of the samples tested were found to be t(11;22) translocations involving EWS-FLI 1 genes. Sixty-one percent (11/18) were found to be type 1 fusion and seven were type 2 (39 percentage). This is the first study in India with quantitative information about the types of EWS-FLI 1 translocations present in Ewing's family of tumours in south Indian patients.

Identification of an immunogenic EWS-FLI1-derived HLA-DR-restricted T helper cell epitope

Immunotherapy with tumor-specific peptide-loaded dendritic cells represents a promising therapeutic approach for patients with multifocal primary or early relapsed Ewing family tumors (EFT). The authors therefore screened a peptide library derived from the fusion region of the EFT-specific chimeric transcription factor EWS-FLI1 for immunogenic peptides. T-cell priming with 10 peptides was evaluated using IFN(gamma) video-assisted automated enzyme-linked immunospot technique. The authors report the identification of the first EFT-specific immunogenic T-cell epitope so far. Its identification will lead to a better understanding of EFT immunology and may improve DC-based immunotherapy.

Inhibition of platelet-derived growth factor-induced cell growth signaling by a short interfering RNA for EWS-Fli1 via down-regulation of phospholipase D2 in Ewing sarcoma cells

EWS-Fli1, a fusion gene resulting from a chromosomal translocation t(11;22, q24;q12) and found in Ewing sarcoma and primitive neuroectodermal tumors, encodes a transcriptional activator and promotes cellular transformation. However, the precise biological functions of its products remain unknown. To investigate the role of EWS-Fli1 in cell growth signaling, we transfected Ewing sarcoma TC-135 cells with short interfering RNAs for EWS-Fli1. EWS-Fli1 knockdown reduced cell growth and platelet-derived growth factor (PDGF)-BB-induced activation of the growth signaling enzymes. Interestingly, phospholipase D2 (but not the PDGF-BB receptor) showed marked down-regulation in the EWS-Fli1-knocked down TC-135 cells compared with the control cells. In Ewing sarcoma TC-135 cells, the PDGF-BB-induced phosphorylation of growth signaling involving extracellular signal-regulated kinase, Akt, p70S6K, and the expression of cyclin D3 were markedly inhibited by transfection with short interfering RNA phospholipase (PL)-D2. The PDGF-BB-induced activation of growth signaling was also suppressed by 1-butanol, which prevents the production of phosphatidic acid by phospholipase D (but not by t-butyl alcohol), thereby implicating PLD2 in PDGF-BB-mediated signaling in TC-135 cells. These results suggest that EWS-Fli1 may play a role in the regulation of tumor proliferation-signaling enzymes via PLD2 expression in Ewing sarcoma cells.

A developmental switch in the response of DRG neurons to ETS transcription factor signaling

Two ETS transcription factors of the Pea3 subfamily are induced in subpopulations of dorsal root ganglion (DRG) sensory and spinal motor neurons by target-derived factors. Their expression controls late aspects of neuronal differentiation such as target invasion and branching. Here, we show that the late onset of ETS gene expression is an essential requirement for normal sensory neuron differentiation. We provide genetic evidence in the mouse that precocious ETS expression in DRG sensory neurons perturbs axonal projections, the acquisition of terminal differentiation markers, and their dependence on neurotrophic support. Together, our findings indicate that DRG sensory neurons exhibit a temporal developmental switch that can be revealed by distinct responses to ETS transcription factor signaling at sequential steps of neuronal maturation.

By expressing ETS transcription factors at different developmental stages of dorsal root ganglion development, the authors show that late onset of ETS expression is essential for normal sensory neuron differentiation

Differential effects of neuropeptide Y on the growth and vascularization of neural crest-derived tumors

Neuropeptide Y (NPY) is a sympathetic neurotransmitter recently found to be potently angiogenic and growth promoting for endothelial, vascular smooth muscle and neuronal cells. NPY and its cognate receptors, Y1, Y2 and Y5, are expressed in neural crest-derived tumors; however, their role in regulation of growth is unknown. The effect of NPY on the growth and vascularization of neuroendocrine tumors was tested using three types of cells: neuroblastoma, pheochromocytoma, and Ewing's sarcoma family of tumors (ESFT). The tumors varied in expression of NPY receptors, which was linked to differential functions of the peptide. NPY stimulated proliferation of neuroblastoma cells via Y2/Y5Rs and inhibited ESFT cell growth by Y1/Y5-mediated apoptosis. In both tumor types, NPY receptor antagonists altered basal growth levels, indicating a regulatory role of autocrine NPY. In addition, the peptide released from the tumor cells stimulated endothelial cell proliferation, which suggests its paracrine angiogenic effects. In nude mice xenografts, exogenous NPY stimulated growth of neuroblastoma tumors, whereas it increased apoptosis and reduced growth of ESFT. However, in both tumors, NPY treatment led to an increase in tumor vascularization. Taken together, this is the first report of NPY being a growth-regulatory factor for neuroendocrine tumors, acting both by autocrine activation of tumor cell proliferation or apoptosis and by angiogenesis. NPY and its receptors may become targets for novel approaches in the treatment of these diseases, directed against both tumor cell proliferation and angiogenesis.

Management of paranasal sinus malignancy

Malignancies of the nasal cavity and paranasal sinuses represent a wide spectrum of histologies, tissues of origin, and anatomic primary sites. The inherent difficulty in generalizing treatment approaches is obvious, given the numerous variables associated with the broadly-based term, paranasal sinus malignancy (PNSCa). Nevertheless, the majority of epithelial and salivary malignancies of this region (ie, squamous cell carcinoma, adenocarcinoma, adenoid cystic carcinoma, sinonasal undifferentiated carcinoma, and esthesioneuroblastoma) require surgical intervention as part of any treatment regimen. Recent trends have broadened the indications for chemotherapeutic and radiotherapeutic options in the management of advanced PNSCa. Nonepithelial malignancies, including the wide variety of sarcomas arising in this region, most commonly require multimodality treatment including chemotherapy, radiation, and/or surgery for definitive treatment. Moreover, the proximity of the nasal cavity and paranasal sinuses to structures including the orbit, dura, brain, cranial nerves, and carotid arteries mandates careful radiologic and neurologic evaluations throughout the course of the disease. Surgical advances now permit complex tumor removal and reconstruction surrounding these structures resulting in functional and cosmetic improvements when compared to earlier techniques. However, additional clinical trials are necessary to systematically evaluate the locoregional control, organ-preservation strategies, and survival related to the variety of treatments currently available.

PI3K/AKT is involved in mediating survival signals that rescue Ewing tumour cells from fibroblast growth factor 2-induced cell death

While in vitro studies had shown that fibroblast growth factor 2 (FGF2) can induce cell death in Ewing tumours, it remained unclear how Ewing tumour cells survive in vivo within a FGF2-rich microenvironment. Serum- and integrin-mediated survival signals were, therefore, studied in adherent monolayer and anchorage-independent colony cell cultures. In a panel of Ewing tumour cell lines, either adhesion to collagen or exposure to serum alone only had a minor protective effect against FGF2. However, both combined led to complete resistance to 5 ng ml(-1) FGF2 in three of four FGF2-sensitive cell lines (RD-ES, RM-82 and WE-68), and to an increased survival as compared to other culture conditions in TC-71 cells. Inhibition studies with LY294002 demonstrated that the serum signal is mediated via the phosphoinositide 3-OH kinase/AKT pathway. Thus, Ewing tumour cells escape FGF2-induced cell death by modulating FGF2 signalling. The tumour microenvironment provides the necessary survival signals by integrin-mediated adhesion and soluble serum factor(s). These survival signals warrant further investigation as a potential resistance mechanism to other apoptosis-inducing agents in vivo.

Favorable outcome of Ewing sarcoma family tumors to multiagent intensive preoperative chemotherapy: a single institution experience

BACKGROUND

Aim of our study was to evaluate the efficacy of multiagent intensive preoperative chemotherapy in patients with Ewing sarcoma family tumors (ESFT), in order to succeed a better percentage of necrosis before surgical resection.

PROCEDURE

Eighteen patients with ESFT were treated with the same multiagent intensive preoperative protocol. 5/18 patients had bone Ewings sarcoma (EWS) and 13/18 had peripheral primitive neuroectodermal tumor (PNET). None had metastases at diagnosis. Chemotherapy consisted of 5 or 6 cycles with vincristine, cisplatin, cyclophosphamide, and Adriamycin, followed by 12 cycles of vincristine, cyclophosphamide, and actinomycin-D. Five patients with EWS underwent total resection after 5-6 cycles of preoperative chemotherapy and prosthetic replacement was performed in two of them. In 3/13 patients with PNET the tumor was resected at diagnosis and in 1/13 after 5 cycles of chemotherapy, while 9/13 patients received chemotherapy only and/or radiotherapy.

RESULTS

In patients with EWS, the histologic specimens of the resected tumors showed that tissue necrosis was 100% in four patients and 95% in one patient. The good histologic response reflects the effectiveness of this regimen in all ESFT. No patient had topical recurrence or developed metastatic disease during follow-up period (2-13 years, mean time 7.4 years). All patients had the scheduled cycles without delays or dose reductions. There were no major side effects of chemotherapy.

CONCLUSIONS

The intensive chemotherapy schedule, comprising of 5-6 cycles preoperatively, seems to maximize the percentage of tumor necrosis, thus improving outcome. Our study implies that this combined therapy may improve the prognosis of ESFT.

PTPL1 is a direct transcriptional target of EWS-FLI1 and modulates Ewing's Sarcoma tumorigenesis

Ewing's Sarcoma family tumors (ESFT) are characterized by a translocation t(11:22) forming an aberrant transcription factor EWS-FLI1. Protein tyrosine phosphatase L1 (PTPL1) was identified as a gene upregulated by EWS-FLI1 in transfected cells by microarray. Our results show that PTPL1 is a transcriptional target of EWS-FLI1 both by chromatin immunoprecipitation and promoter activation studies. We demonstrate that PTPL1 is highly expressed in ESFT cells and patient tumors compared with normal tissues, with a trend towards higher expression in metastatic versus primary tumors. Reduction of PTPL1 protein in ESFT cells correlated with a significant reduction in both monolayer and soft-agar cell growth. In addition, these PTPL1-reduced cells were more sensitive to etoposide-induced apoptosis than the controls. We therefore report a novel transcriptional activation of a phosphatase involved in the oncogenesis of ESFT. Increasing interest in specific phosphatase inhibitors would allow PTPL1 to be evaluated as a therapeutic target in ESFT.

Primitive neuroectodermal tumor (PNET) of the uterus in a renal allograft patient: a case report

The incidence of malignancy after renal transplant has been reported to range from 4% to 18%. Tumors of the skin and lip tend to be the most common with non-Hodgkin lymphoma comprising 20% of all neoplasms. Primitive neuroectodermal tumors (PNET) are collectively described as being a part of the Ewing sarcoma family of tumors. PNET occur more commonly in the second decade of life, predominantly affecting Whites and Hispanics, and rarely occur in individuals of African or Asian descent. The most common primary site of involvement is along the central axis, particularly the chest (Askin tumor), but it can arise in any soft tissue. PNET also occur in the head and neck. PNET involving the cervix, urinary bladder, uterus, and vagina have been reported. We describe a case of a 15-year-old female who, 9 years after receiving a living related renal transplant, developed a post-transplant PNET of the uterus.

Recombinant EWS-FLI1 oncoprotein activates transcription

The Ewing's sarcoma family of tumors (ESFT) contains a characteristic translocation the chimeric transcript of which is translated to become the EWS-FLI1 fusion protein. EWS-FLI1 regulates transcription and posttranscriptional splicing. Elimination of EWS-FLI1 protein from ESFT cells induces apoptosis and reduces xenograft tumor growth. Therefore the production of a biologically active recombinant EWS-FLI1 could lead to discoveries that would enhance our mechanistic understanding of ESFT. We have cloned, expressed, and purified a biologically active recombinant EWS-FLI1 in Escherichia coli using affinity column chromatography. A refolding procedure was required to render the recombinant EWS-FLI1 soluble in relatively native conditions. The structural alterations induced by the refolding procedure were monitored by SDS-gel electrophoresis, circular dichroism, and steady-state fluorescence spectroscopy. Recombinant EWS-FLI1 under native conditions approaches a largely unfolded conformation. Recombinant EWS-FLI1 protein under native conditions specifically binds to DNA and transcribes RNA. Our biologically active recombinant EWS-FLI1 oncoprotein will be useful to identify functional molecular partners and inhibitors.

Biology and therapeutic advances for pediatric osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and adolescents. Survival for these patients was poor with the use of surgery and/or radiotherapy. The introduction of multi-agent chemotherapy dramatically improved the outcome for these patients and the majority of modern series report 3-year disease-free survival of 60%-70%. This paper describes current strategies for treating patients with osteosarcoma as well as review of the clinical features, radiologic and diagnostic work-up, and pathology. The authors review the state of the art management for patients with osteosarcoma in North America and Europe including the use of limb-salvage procedures and reconstruction as well as discuss the etiologic and biologic factors associated with tumor development. Therapy-related sequelae and future directions in the biology and therapy for these patients are also discussed.

Characterization of hnRNP K protein-RNA interactions

The heterogeneous nuclear ribonucleoprotein K protein is an RNA-binding protein found in several subcellular compartments where it is thought to be involved in signaling multiple processes that compose gene expression. K protein contains three K homology (KH) domains that mediate RNA-binding. We used a serial analysis of gene expression (SAGE)-based strategy, yeast three-hybrid screen, RNA pull-down assays and computational analysis to characterize K protein-associated RNAs. We demonstrate that K protein interacts with many sense and antisense nuclear and mitochondrial transcripts through both direct and indirect binding. The highly specific direct binding of transcripts to K protein is mediated by a consensus sequence comprising three C-rich patches. Structural analysis suggests a three-prong interaction model whereby each of the three KH domains binds one of the C-rich patches. Genome-wide and yeast three-hybrid clone analysis revealed that these sequences are located preferentially in the 3' untranslated regions, which are known to regulate mRNA translation and processing.

Imatinib inhibits proliferation of Ewing tumor cells mediated by the stem cell factor/KIT receptor pathway, and sensitizes cells to vincristine and doxorubicin-induced apoptosis

PURPOSE AND EXPERIMENTAL DESIGN

The stem cell factor/KIT receptor loop may represent a novel target for molecular-based therapies of Ewing tumor. We analyzed the in vitro impact of KIT blockade by imatinib in Ewing tumor cell lines.

RESULTS

KIT expression was detected in 4 of 4 Ewing tumor cell lines and in 49 of 110 patient samples (44.5%) by immunohistochemistry and/or Western blot analysis. KIT expression was stronger in Ewing tumors showing EWS-FLI1 nontype 1 fusions. Despite absence of c-kit mutations, constitutive and ligand-inducible phosphorylation of KIT was found in all tumor cell lines, indicating an active receptor. Treatment with KIT tyrosine kinase inhibitor imatinib (0.5-20 micro M) induced down-regulation of KIT phosphorylation and dose response inhibition of cell proliferation (IC(50), 12-15 micro M). However, imatinib administered alone at doses close to IC(50) for growth inhibition (10 micro M) did not induce a significant increase in apoptosis. We then analyzed if blockade of KIT loop through imatinib (10 micro M) was able to increase the antitumor in vitro effect of doxorubicin (DXR) and vincristine (VCR), drugs usually used in Ewing tumor treatment. Addition of imatinib decreased in 15-20 and 15-36% of the proliferative rate of Ewing tumor cells exposed to DXR and VCR, respectively, and increased in 15 and 30% of the apoptotic rate of Ewing tumor cells exposed to the same drugs.

CONCLUSIONS

Inhibition of Ewing tumor cell proliferation by imatinib is mediated through blockade of KIT receptor signaling. Inhibition of KIT increases sensitivity of these cells to DXR and VCR. This study supports a potential role for imatinib in the treatment of Ewing tumor.

The prognostic and therapeutic relevance of p27kip1 in Ewing's family tumors

PURPOSE

Ewing's family tumors (EFTs) display the characteristic fusion gene EWS-Fli1. We have reported EWS-Fli1 may promote the cell cycle progression accompanied by the suppression of the expression of cyclin-dependent kinase inhibitor p27(kip1) in EFT cells. Here, we describe the prognostic and therapeutic relevance of p27 in EFTs.

EXPERIMENTAL DESIGN

We examined tumor samples taken from 21 patients with primary EFTs for the expression of p27 protein immunohistochemically and evaluated its correlation with clinical outcome. We also investigated the usefulness of p27 as a therapeutic strategy in vitro and in vivo using p27 expression adenovirus. Finally, we examined the process of EWS-Fli1-mediated reduction of p27 expression.

RESULTS

Immunohistochemical analysis showed that a low expression level of p27 protein was related to poor event-free survival in an univariate analysis and that the expression level of p27 correlated more significantly with patient survival than several clinical factors in a multivariate survival analysis. Overexpression of p27 with the adenoviral vector remarkably inhibited the cell growth in all EFT cells tested and further induced apoptosis in the wild-type p53 EFT cells. In vivo studies demonstrated a reduction in tumor growth of EFT xenograft in nude mice treated with the intratumoral injection of p27-expressing adenovirus. EWS-Fli1 did not significantly affect the p27 promoter activity and p27 mRNA levels. However, the challenge of the proteasome inhibitor caused accumulation of p27 protein in EFT cells. These data strongly suggest EWS-Fli1 might attenuate p27 protein level via activation of the proteasome-mediated degradation pathway.

CONCLUSIONS

Our findings provide the first evidence of the prognostic relevance of p27 expression in EFTs. We propose p27 as a novel and powerful therapeutic factor for the molecular target therapy of EFTs.

Type I interferon and TNFalpha cooperate with type II interferon for TRAIL induction and triggering of apoptosis in SK-N-MC EWING tumor cells

Ewing's sarcoma is the second most common human bone tumor in childhood. Here, we investigated the sensitivity of the Ewing tumor cell line, SK-N-MC, to the apoptotic effect of type I (IFNalpha) and type II (IFNgamma) interferons and TNFalpha. We demonstrate that although IFNalpha and TNFalpha alone are unable to induce cell death, they act in synergy with IFNgamma to induce SK-N-MC cell apoptosis. The synergistic induction of apoptosis correlated with the synergistic induction of TNFalpha-related apoptosis-inducing ligand (TRAIL) mRNA and TRAIL protein synthesis as well as of TRAIL secretion. Preparations of inducer-free supernatants from SK-N-MC cells stimulated with combinations of cytokines were shown to be cytotoxic for untreated SK-N-MC cells. This cytotoxicity was partially inhibited by addition of TRAILR2/Fc fusion protein, indicating that the secreted TRAIL mediates, at least in part, the apoptotic effect displayed by the supernatants of stimulated SK-N-MC cells. We have shown that the presence of IFNgamma is required to allow the sustained expression of IRF1 in SK-N-MC cells stimulated by addition of IFNalpha or TNFalpha suggesting that IRF1 plays a role in the synergistic induction of apoptosis by combinations of cytokines. Furthermore, we have shown that inhibition of NF-kappaB activation contributes to the IFNgamma-mediated sensitization to the apoptotic effect of TNFalpha. To our knowledge, this is the first report showing that interferon/cytokine combinations are able to induce TRAIL gene expression and TRAIL protein synthesis and secretion in Ewing sarcoma-derived cells. We believe that the observations reported here might contribute to the development of alternative new approaches to the treatment of Ewing tumors resistant to conventional therapy.

Abdominal small round cell tumor with osteoid and EWS/FLI1

In this report, we described a case of multiple intraperitoneal tumors. Histologically, the tumors were composed of small round cells with malignant phenotype, necrotic areas, and islands of osteoid matrix in the stroma. In immunohistochemical and molecular analyses, the tumors expressed CD99 and EWS-Fli1 fusion gene. Production of osteoid by small round tumor cells was consistent with the histologic criteria of small-cell osteosarcoma, whereas expression of EWS-Fli1 was a characteristic genetic feature of Ewing's sarcoma family of tumor. Such tumors have been limited to a case in which histologically proven small-cell osteosarcoma of the scapula showed a chromosomal translocation, t(11;22)(q24;q12).

Pelvic primitive neuroectodermal tumor associated with a cluster of small round cell tumors: case report and review of current literature

BACKGROUND

Peripheral primitive neuroectodermal tumor (pPNET) is aggressive and rare, comprising 1% of soft tissue sarcomas. Involvement of the reproductive tract is unusual.

CASE

A 35-year-old woman had a pelvic mass and omental cake. Frozen-section examination at laparotomy revealed small round cell tumor confirmed as pPNET. Chemotherapy with vincristine, doxorubicin, and cyclophosphamide alternating with ifosfamide and etoposide with mesna yielded complete response. The patient's mother died of a similar tumor at age 52 years, and the patient's husband had adult Ewing sarcoma, constituting an unusual cluster of related tumors.

CONCLUSIONS

Genetic recombination resulting in a chimeric transcript of the Ewing sarcoma gene and the Friend leukemia virus integration site is characteristic of these tumors. Surgical resection and multiagent chemotherapy may enhance survival.

Primitive neuroectodermal tumor and extraskeletal Ewing sarcoma arising primarily around the spinal column: report of four cases and a review of the literature

STUDY DESIGN

Report of four cases and a review of the literature.

OBJECTIVES

To study the clinical features and prognosis of primitive neuroectodermal tumor or extraskeletal Ewing sarcoma arising around the spinal column.

SUMMARY OF BACKGROUND DATA

Primitive neuroectodermal tumor or extraskeletal Ewing sarcoma that originates around the spinal column is very rare, and its prognosis is very poor.

METHODS

Four patients were diagnosed and underwent treatment.

RESULTS

Although all the patients received high-dose chemotherapy with or without radiotherapy after surgery, three patients died of the disease. Only one patient who received en bloc resection of the tumor combined with multiagent chemotherapy followed by high-dose chemotherapy with peripheral blood stem cell transplantation remains alive and continues to be disease free.

CONCLUSION

The prognosis of the patients with primitive neuroectodermal tumor or extraskeletal Ewing sarcoma around the spinal column is very poor. Multiagent chemotherapy combined with en bloc resection and radiation therapy is the preferred treatment for patients with primitive neuroectodermal tumor or extraskeletal Ewing sarcoma around the spinal column.

Identification of a DNA-binding site and transcriptional target for the EWS-WT1(+KTS) oncoprotein

Desmoplastic small round cell tumor (DSRCT) is defined by a chimeric transcription factor, resulting from fusion of the N-terminal domain of the Ewing's sarcoma gene EWS to the three C-terminal zinc fingers of the Wilms' tumor suppressor WT1. Although DNA-binding sites have been defined for the uninterrupted WT1 zinc finger domains, the most prevalent isoforms of both WT1 and EWS-WT1 have an insertion of three amino acids [lysine, threonine, and serine (KTS)], which abrogates binding to known consensus sequences and transactivation of known target genes. Here, we used cDNA subtractive hybridization to identify an endogenous gene, LRRC15, which is specifically up-regulated after inducible expression of EWS-WT1(+KTS) in cancer cell lines, and is expressed within primary DSRCT cells. The chimeric protein binds in vitro and in vivo to a specific element upstream of LRRC15, leading to dramatic transcriptional activation. Mutagenesis studies define the optimal binding site of the (+KTS) isoform of EWS-WT1 as 5'-GGAGG(A/G)-3'. LRRC15 encodes a leucine-rich transmembrane protein, present at the leading edge of migrating cells, the expression of which in normal tissues is restricted to the invasive cytotrophoblast layer of the placenta; small interfering (siRNA)-mediated suppression of LRRC15 expression in breast cancer cells leads to abrogation of invasiveness in vitro. Together, these observations define the consequence of (KTS) insertion within WT1-derived zinc fingers, and identify a novel EWS-WT1 transcriptional target implicated in tumor invasiveness.

The epidermal growth factor receptor HER2 is not a major therapeutic target in Ewing sarcoma

BACKGROUND

Although chimeric EWS gene and Ets gene fusions are pathognomonic of Ewing sarcoma (ES) and primitive neuroectodermal tumors (PNET), the molecular pathogenesis of these pediatric malignancies is poorly understood. Recently, the human epidermal growth factor (HER)-2 receptor, which plays an important role in the biology of certain epithelial cancers, has been implicated in ES tumor cell line growth and chemosensitivity.

MATERIALS

To investigate whether HER2 might be a rational target for ES/PNET therapy, five ES cell lines and 13 archival primary ES/PNET samples were examined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for evidence of HER2 overexpression.

RESULTS

Although several ES cell lines demonstrated modest constitutive HER2 expression by immunoblot, none of the ES cell lines or primary tumor samples showed evidence of HER2 overexpression by IHC or HER2 gene amplification by FISH. Moreover, treatment of human ES cell lines with the HER2-targeted agent trastuzumab (Herceptin) had little effect on cell survival, proliferation, or growth in semi-solid medium.

CONCLUSIONS

These results suggest that HER2 is not a biologically or therapeutically important pathway in ES/PNET.

PIM3 proto-oncogene kinase is a common transcriptional target of divergent EWS/ETS oncoproteins

Despite significant structural diversity, present evidence suggests that EWS/ETS fusion proteins promote oncogenesis by transcriptionally modulating a common set of target genes. In order to identify these genes, microarray expression analyses were performed on NIH 3T3 polyclonal populations expressing one of three EWS/ETS fusion genes. The majority of these genes can be grouped into seven functional categories, including cellular metabolism and signal transduction. The biologic significance of these target genes was pursued. The effects of modulating genes involved in metabolism were assessed by flux studies and demonstrated shifts in glucose utilization and lactate production as a result of EWS/FLI1 expression. The proto-oncogene coding for serine/threonine kinase PIM3 was found to one of several genes encoding signal transduction proteins that were up-regulated by EWS/ETS fusions. PIM3 was found to be expressed in a panel of human Ewing's family tumor cell lines. Forced expression of PIM3 promoted anchorage-independent growth. Coexpression of a kinase-deficient PIM3 mutant attenuated EWS/FLI1-mediated NIH 3T3 tumorigenesis in immunodeficent mice.

Primary primitive peripheral neuroectodermal tumor of the prostate. Immunophenotypic and molecular study of a case

A case of primitive peripheral neuroectodermal tumor arising in the prostate gland of a 31-year-old man and first diagnosed through a biopsy is reported. Microscopically, the tumor was made up of solid nests and sheets of small round cells, and it was difficult to distinguish the neoplasm from other small round cell tumors, such as small cell carcinoma, rhabdomyosarcoma, or malignant lymphoma. Immunohistochemically, the tumor cells showed immunoreactivity for CD99, vimentin, neuron-specific enolase, and synaptophysin. The neoplasm was excised by a radical surgical procedure preceded by chemotherapy and radiation therapy. The morphologic diagnosis of the prostatectomy specimen was complemented by molecular analysis performed on viable microdissected tissue obtained from formalin-fixed, paraffin-embedded tumor sections. Polymerase chain reaction and sequencing assessment showed the presence of EWS/FLI1 type 2 chimeric transcript, confirming the diagnosis of peripheral primitive neuroectodermal tumor. To our knowledge, this is the first description of a primary peripheral primitive neuroectodermal tumor in the prostate gland.

Performance characteristics of a reverse transcriptase-polymerase chain reaction assay for the detection of tumor-specific fusion transcripts from archival tissue

Pediatric small round cell tumors still pose tremendous diagnostic problems. In difficult cases, the ability to detect tumor-specific gene fusion transcripts for several of these neoplasms, including Ewing sarcoma/peripheral primitive neuroectodermal tumor (ES/PNET), synovial sarcoma (SS), alveolar rhabdomyosarcoma (ARMS), and desmoplastic small round cell tumor (DSRCT) using reverse transcriptase-polymerase chain reaction (RT-PCR), can be extremely helpful. Few studies to date, however, have systematically examined several different tumor types for the presence of multiple different fusion transcripts in order to determine the specificity and sensitivity of the RT-PCR method, and no study has addressed this issue for formalin-fixed material. The objectives of this study were to address the specificity, sensitivity, and practicality of such an assay applied strictly to formalin-fixed tissue blocks. Our results demonstrate that, for these tumors, the overall sensitivity for detecting each fusion transcript is similar to that reported in the literature for RT-PCR on fresh or formalin-fixed tissues. The specificity of the assay is very high, being essentially 100% for each primer pair when interpreting the results from visual inspection of agarose gels. However, when these same agarose gels were examined using Southern blotting, a small number of tumors also yielded reproducibly detectable weak signals for unexpected fusion products, in addition to a strong signal for the expected fusion product. Fluorescence in situ hybridization (FISH) studies in one such case indicated that a rearrangement that would account for the unexpected fusion was not present, while another case was equivocal. The overall specificity for each primer pair used in this assay ranged from 94 to 100%. Therefore, RT-PCR using formalin-fixed paraffin-embedded tissue sections can be used to detect chimeric transcripts as a reliable, highly sensitive, and highly specific diagnostic assay. However, we strongly suggest that the final interpretation of the results from this assay be viewed in light of the other features of the case, including clinical history, histology, and immunohistochemistry, by the diagnostic pathologist. Additional studies such as FISH may be useful in clarifying the nature of equivocal or unexpected results.

A systematic review of molecular and biological markers in tumours of the Ewing's sarcoma family

The aims of this study were to perform the first systematic review of molecular and biological tumour markers in tumours of the Ewing's sarcoma family (ESFT), and evaluate the current evidence for their clinical use. A well-defined, reproducible search strategy was used to identify the relevant literature from 1966 to February 2000. Papers were independently assessed for tumour markers used in the screening, diagnosis, prognosis or monitoring of patients with ESFT. Eighty-four papers studying the use of 70 different tumour markers in ESFT's were identified. Low-quality, inconsistent reporting limited meta-analysis to that of prognostic data for 28 markers. Patients with tumours lacking S-100 protein expression have a better overall survival (OS) (hazard ratio (HR)=0.41, 95% confidence interval (CI) 0.19, 0.89) than those with expression; patients with high levels of serum LDH had a worse OS and disease-free survival (DFS) (OS: HR=2.92, CI 2.16, 3.94, DFS: HR=3.38, 95% CI 2.28, 4.99); patients with localised disease and tumours expressing type 1 EWS-FLI1 fusion transcripts had an improved DFS compared with those with other fusion transcript types (HR=0.17, 95% CI 0.079, 0.37). The knowledge base formed should facilitate more informative future research. Improved statistical reporting and large, multicentre prospective studies are advocated.

Molecular genetic diagnosis of pediatric cancer: current and emerging methods

A wide array of diagnostic tests are available to evaluate molecular abnormalities in pediatric cancer. Classic cytogenetics, FISH, flow cytometry, PCR, and Southern blot analysis are in widespread use throughout pediatric hospitals. Examples of the application of these methods in pediatric cancer diagnosis are reviewed. Newer methods such as CGH, SKY, gene expression microarrays and proteomic methods are under active investigation andwill almost certainly lead to significant advances in our ability to diagnose and treat pediatric cancer.

Current concepts in the treatment of Ewing's sarcoma

Current concepts in the treatment of patients with Ewing's sarcoma are presented focusing on the role of chemotherapy, radiation therapy and surgical resection. Particular attention is given to current methods of limb salvage. Problem areas, including the pelvis, proximal femur and spine, are discussed.

Induction of BAIAP3 by the EWS-WT1 chimeric fusion implicates regulated exocytosis in tumorigenesis

Desmoplastic small round cell tumor (DSRCT) is defined genetically by the chimeric fusion of the Ewing's sarcoma and Wilms' tumor genes, generating a novel transcription factor, EWS-WT1. By using cells with inducible EWS-WT1 to screen high-density microarrays, we identified BAIAP3 as a transcriptional target of the chimera. The BAIAP3 promoter is specifically bound in vivo by the (-KTS) isoform of EWS-WT1, consistent with its activation in reporter assays. BAIAP3 encodes a protein implicated in regulated exocytosis, which is colocalized with a secreted growth factor within cytoplasmic organelles. Ectopic expression of BAIAP3 in tumor cells dramatically enhances growth in low serum and colony formation in soft agar. BAIAP3 therefore encodes a transcriptional target of an oncogenic fusion protein that implicates the regulated exocytotic pathway in cancer cell proliferation.

Primitive neuroectodermal tumors of the pancreas: a report of seven cases of a rare neoplasm

Primitive neuroectodermal tumors (PNETs) have rarely been described in solid organs. We report a series of seven PNETs of the pancreas. The clinical, gross, microscopic, and immunohistochemical features of these seven PNETs of the pancreas are described, as are the genetic analyses in five cases. The patients ranged in age from 6 to 25 years (mean 18 years). Four of the patients were male. All of the patients presented with jaundice and/or abdominal pain. All of the tumors were located in the head of the pancreas, and they ranged in size from 3.5 to 9.0 cm. Light microscopy revealed the typical morphologic features of PNETs. By immunohistochemistry the neoplastic cells in all seven cases expressed O13 (CD99, p30/32MIC2). In five of six tested cases, the neoplastic cells also expressed cytokeratin. All of the tumors expressed neural-neuroendocrine markers. Two of the three cases examined ultrastructurally showed prominent epithelial features. There was cytogenetic or molecular genetic evidence of the t(11;22)(q24;q12) in four of five cases examined. Clinical follow-up was available in five cases. Two of the patients were alive with no evidence of disease at 33 and 43 months. One patient was alive with disease at 27 months. One patient died of postoperative complications. Another patient died of disease 4 years after diagnosis. PNET can sometimes arise as a primary neoplasm of the pancreas. Like PNETs arising in more conventional sites, pancreatic PNETs occur in the pediatric and adolescent population, show the characteristic staining with O13, and typically harbor the t(11;22)(q24;q12) chromosomal translocation. PNETs should be included in the differential diagnosis of poorly differentiated small round cell tumors of the pancreas. Moreover, they should not be confused with pancreatic endocrine tumors, which also demonstrate dual epithelial and neuroendocrine differentiation by immunohistochemistry and express O13 in 30% of cases.

Soft tissue sarcoma in children: prognosis and management

Soft tissue sarcomas (STS) account for approximately 7% of malignant neoplasms in children. The heterogeneity of STS makes the diagnosis and therapy particularly difficult and should be reserved for specialized centers with expertise in treating cancer in children. Major progress in the accuracy of diagnosis and classification has been made by the identification of specific, recurring genetic alterations t(2;13)(q35;q14) and t(1;13)(p36;q14) in alveolar rhabdomyosarcomas (RMS), t(X;18)(p11;q11) for synovial sarcoma (SS) and t(11;22)(q24;q12) or t(21;22)(q22;q12) for Ewing's tumor family. As a result of large multicenter STS studies, such as the North-American Intergroup Rhabdomyosarcoma Study, the German Pediatric Soft Tissue Sarcoma Study Group (CWS), Italian Gruppo Cooperativo Italiano study and Sociètè Internationale d'Oncologie Pèdiatrique (SIOP) Malignant Mesenchymal Tumors study, the identification of more effective treatment strategies and improvement in prognosis have been made in the last 30 years. Prognostic variables were identified and, by exploring novel therapeutic strategies, criteria were established for the use of preoperative chemotherapy and radiotherapy, and primary and delayed second-look surgery. As a result of evaluation of different drugs active in STS, refinements in the utilization of chemotherapy have been made possible. Clinical trials have also been instrumental in defining the late effects of treatment. In STS the following drugs have proven to be useful: dactinomycin, vincristine, alkylating agents such as cyclophosphamide and ifosfamide, as well as anthracyclines such as doxorubicin (adriamycin) and epi-doxorubicin. Recommendations for radiation are dependent on the primary site and size of the tumour, histology, patient age and the extent of disease before and after surgical resection. In general, with conventional fractionation (1 x 1.8 to 2 Gy/day) radiotherapy doses between 40 and 50 Gy should be administered. The German CWS group explored the effectiveness of 32 Gy when accelerated and hyperfractionated, and given simultaneously to chemotherapy, and found it adequate for local tumor control in patients with selected favorable prognostic factors. When treated with a combination of chemotherapy and local therapy, STS showed an event-free survival between 50 and 80% [RMS 70%, extraskeletal Ewing sarcoma (EES) and peripheral neuroectodermal tumor (PNET) circa 50%, and SS 70 to 80%]. About one-fifth of patients with newly diagnosed RMS-like STS have metastatic disease. The 5-year survival rate among these patients is low (20 to 30%). Age (>10 years), bone, and/or bone marrow metastases are associated with a very poor prognosis (survival rate of about 5%). The value of high dose chemotherapy with hematopoietic stem cell rescue in patients with poor prognostic STS remains unclear and should be performed in controlled studies only.

Induction of the interleukin-2/15 receptor beta-chain by the EWS-WT1 translocation product

EWS-WT1 is a chimeric transcription factor resulting from fusion of the N-terminal domain of the Ewing sarcoma gene EWS to the three C-terminal zinc fingers of the Wilms tumor suppressor WT1. This translocation underlies desmoplastic small round cell tumor (DSRCT), which is noted for the abundance of reactive stroma surrounding islets of tumor cells, suggestive of paracrine signals contributing to tumor cell proliferation. Hybridization to high-density oligonucleotide microarrays can be used to identify targets of EWS-WT1. Expression of EWS-WT1 from a tetracycline-regulated promoter leads to the induction of growth-associated genes, of which the most remarkable is the beta-chain of the interleukin-2/15 receptor (IL-2/15Rbeta). Potent transcriptional activation by the chimeric protein maps to two bindings sites within the IL-2/15Rbeta promoter. Analysis of primary DSRCT tumor specimens demonstrates high levels of IL-2/15Rbeta within the tumor cells, along with expression of IL-2 and IL-15 by the abundant hyperplastic endothelial cells within the reactive stroma. Activation of this cytokine signaling pathway is consistent with the nuclear localization of its downstream effectors, phosphorylated STAT3 and STAT5. These observations suggest that the transcriptional induction of a cytokine receptor by a tumor-associated translocation product enables a proliferative response of epithelial cancer cells to ligands secreted by the surrounding stroma.

Inhibition of constitutive NF-kappa B activity suppresses tumorigenicity of Ewing sarcoma EW7 cells

Ewing sarcoma is 1 of the most aggressive tumors that can affect children and young adults. Despite advances in therapy, the prognosis remains poor emphasizing the need for defining new targets for treatment. We investigated a possible role of nuclear factor-kappa B (NF-kappa B) activity of Ewing sarcoma-derived EW7 cells in their tumorigenicity. In these cells, expression of a degradation-resistant form of the inhibitory factor I kappa B alpha inhibited NF-kappa B activity without affecting their in vitro proliferation rate. It causes, however, a remarkable loss of their ability to generate tumors in nude mice that correlates with both a decrease in extracellular matrix (ECM) protein secretion and an acquisition of sensitivity to murine tumor necrosis factor alpha (TNF alpha)-induced apoptosis. These data support the concept that NF-kappa B activity plays a role in the tumorigenicity of Ewing sarcoma cells, identifying NF-kappa B as a potential target for reducing Ewing tumor progression.

Primary Ewing's sarcoma/primitive neuroectodermal tumor of the kidney: a clinicopathologic and immunohistochemical analysis of 11 cases

Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an extraordinarily rare primary tumor in the kidney and can be mistaken for a variety of other round cell tumors, including blastema-predominant Wilms' tumor (WT). Approximately 90% of ES/PNET have a specific t(11;22), which results in a chimeric EWS-FLI-1 protein. Immunohistochemistry for the carboxy-terminus of FLI-1 is sensitive and highly specific for the diagnosis of ES/PNET. WT-1, the WT-associated tumor suppressor gene, is overexpressed in WT but not in ES/PNET. No study has examined FLI-1 or WT-1 expression in renal ES/PNET. The clinicopathologic features of 11 renal ES/PNET were studied along with immunohistochemistry for cytokeratin, desmin, CD99, FLI-1, and WT-1. WT were also immunostained for CD99 (5 cases), FLI-1 (10 cases), and WT-1 (9 cases). The patients (6 men, 5 women) ranged from 18 to 49 years of age (mean, 34 yr). The mean tumor size was 11.8 +/- 3.8 cm (mean +/- standard deviation). Presenting symptoms included abdominal/flank pain and/or hematuria. Grossly, all tumors showed necrosis and hemorrhage, and 4 had cystic change. Microscopically, all tumors showed vaguely lobular growth, primitive round cells, and variable rosette formation. Epithelial, myogenous, or cartilaginous differentiation was not seen. Immunohistochemical results on the renal ES/PNET were cytokeratin (2/8 focal), desmin (0/9), CD99 (8/8), FLI-1 (5/8), and WT-1 (0/8). In comparison, the WT only rarely expressed CD99 (1/5) and did not express FLI-1 (0/10), but were usually WT-1-positive (7/9). Follow-up on 8 cases (mean, 28 mo; range, 6-64 mo) showed 4 lung and pleural metastases, 1 bone metastasis, liver metastasis, 2 local recurrences, and 5 deaths from disease (median time to death, 16.8 mo). No case had distant metastatic disease at presentation. Adjuvant therapy included chemotherapy (8 cases), radiation (3 cases), and bone marrow transplantation (1 case). Our study affirms a unique proclivity of renal ES/PNET for young adults and that it is a highly aggressive neoplasm, with rapid death in many cases, usually after the development of treatment-resistant lung metastases. These tumors must be distinguished from blastema-predominant WT and other primitive renal tumors that require different therapy. FLI-1 and WT-1 immunohistochemistry may be valuable in this differential diagnosis, given the known immunophenotypic overlap between ES/PNET and blastema-predominant WT with regard to CD99, cytokeratin, and desmin. The accurate distinction between these two entities has clear prognostic and therapeutic implications.

The expression of ccn3(nov) gene in musculoskeletal tumors

The CCN3(NOV) protein belongs to the CCN [cysteine-rich CYR61, connective tissue growth factor (CTGF), nephroblastoma overexpressed gene (Nov)] family of growth regulators, sharing a strikingly conserved multimodular organization but exhibiting distinctive functional features. Although previous studies have revealed an expression of CCN3 protein in several normal tissues, including kidney, nervous system, lung, muscle, and cartilage, less is known about its expression in tumors. In this study, we analyzed the expression of CCN3 in musculoskeletal tumors, using a panel of human cell lines and tissue samples. An association between CCN3 expression and tumor differentiation was observed in rhabdomyosarcoma and cartilage tumors, whereas, in Ewing's sarcoma, the expression of this protein seemed to be associated with a higher risk to develop metastases. CCN3 expression was found in 15 of 45 Ewing's sarcoma tissue samples. In particular, we did not observe any expression of CCN3 in the 15 primary tumors that did not develop metastases. In contrast, 15 of the 30 primary tumors that developed lung and/or bone metachronous metastases showed a high expression of the protein (P < 0.001, Fisher's test). Our studies indicate that CCN3 is generally expressed in the cells of the musculoskeletal system. This protein may play a role both in normal and pathological conditions. However, the regulation of CCN3 expression varies in the different neoplasms and depends on the type of cells. Thus, as reported for other CCN genes, the biological properties and regulation of expression of CCN3 are dependent on the cellular context and the nature of the cells in which it is produced. Further studies will help to clarify the biological role of this protein in musculoskeletal neoplasms.

Ewing tumour: incidence, prognosis and treatment options

Ewing tumours, i.e. Ewing's sarcoma and malignant peripheral neuroectodermal tumours, are the second most common primary malignant tumours of bone in childhood and adolescence, with an annual incidence rate in Caucasians of 3 per 1 million children <15 years of age. Histopathologically small blue round cell tumours, Ewing tumours show a typical chromosomal rearrangement in >95% of cases linking the EWS gene on chromosome 22q12 to a member of the ETS transcription gene family, most commonly to Fli-1 on 11q24. This fusion contributes to the malignant potential of Ewing tumour cells, indeed antisense oligonucleotides may prevent tumour growth in vitro. After open biopsy, and histological and possibly molecular biological confirmation of the diagnosis, treatment consists of several months of multidrug cytostatic therapy and local therapy. Both surgery and radiotherapy may control local disease, but without consequent cytostatic chemotherapy all patients will eventually succumb to distant metastases. With the use of alkylating agents including doxorubicin, cyclophosphamide and/or ifosfamide, and other cytostatic drugs such as actinomycin D (dactinomycin), vincristine and etoposide, long-term survival can be achieved in >50% of patients with localised disease. Patients with clinically detectable metastases at diagnosis, patients not responding to therapy and patients with disease relapse have a significantly poorer prognosis. Maximum supportive care and local therapy managed by an experienced physician are required in all patients, and inclusion of high-risk patients in phase I and II studies is warranted. Hence, treatment of patients with Ewing tumours should be performed in experienced centres only and preferably within controlled clinical trials.