Fusion of an ETS-family gene, EIAF, to EWS by t(17;22)(q12;q12) chromosome translocation in an undifferentiated sarcoma of infancy

Sensitive detection of rare Ewing's sarcoma cells in peripheral blood by reverse transcriptase polymerase chain reaction

Disseminated disease is very important in the clinical assessment of pediatric sarcomas. Several reports suggest that reverse transcriptase polymerase chain reaction (RT-PCR) holds great promise in the early staging of cancer patients in general. However, the complexities of these protocols hamper adequate standardization, and their application as routine diagnostic tools has been difficult. The aim of this study is to assess the actual minimal number of tumor cells that may be detected by RT-PCR in a blood sample. Specific tumor cell dilutions from a Ewing's sarcoma cell line reconstituted in peripheral blood from healthy individuals were "ficolled" and submitted to RNA extraction for cDNA preparation and PCR amplification of the t(11-22) (q24;q12) fusion transcript. After PCR amplification, we were able to detect the EWS/FI-1 chimeric gene product at a dilution of 10 tumor cells per 1 or 2 mL of blood. Our simple method supports a role for routine clinical use of RT-PCR in the detection of circulating Ewing's sarcoma cells.

A novel EWS-ERG rearrangement generating two hybrid mRNAs in a peripheral primitive neuroectodermal tumour (pPNET) with a t(15;22) translocation

The occurrence of a t(15;22) translocation in a peripheral primitive neuroectodermal tumour (pPNET) has been previously reported. Molecular examination revealed the presence in tumour mRNA of two hybrid transcripts containing the 5' portion of the EWS gene fused to the 3' portion of the ERG gene. Sequence analyses indicated that both aberrant mRNAs most likely originated from the same rearrangement, which produced different hybrid isoforms due to the presence of an alternatively spliced exon in the ERG gene. To the authors' knowledge, this is the first report of the detection of two hybrid EWS-ERG mRNAs within the same tumour.

Chromosome translocation based on illegitimate recombination in human tumors

Recurrent chromosome translocations in nonhematological tumors are restricted to specific subtypes, and their mechanism is currently unknown. Analysis of the sequence data of 113 interchromosomal junctions derived from 77 Ewing's tumors carrying the characteristic t(11;22) translocation indicate that, in this tumor, translocations are initiated independently on each chromosome in regions that lack site specific recombination signal. Local sequence duplications, deletions, and, most importantly, inversions that are diagnostic of DNA hairpin formation indicate that, at the breakpoint, single-stranded DNA ends are processed individually before interchromosomal joining. Taken together, these observations suggest that chromosome translocations in Ewing's tumors are mediated through a genuine illegitimate recombination mechanism.

Molecular genetics in the diagnosis and prognosis of solid pediatric tumors

The field of molecular genetics continues to see an ever increasing number of applications to pediatric tumor analysis. Studies in pediatric tumors have identified novel genes and other genetic changes, a large number of which reflect one of the following mechanisms: (1) activation of proto-oncogenes; (2) loss of tumor suppressor genes; or (3) creation of novel fusion proteins. At least one of these mechanisms is operational in each of the following pediatric tumors: neuroblastoma, Ewing sarcoma and peripheral primitive neuroectodermal tumor (pPNET), intra-abdominal desmoplastic small-cell tumor, rhabdomyosarcoma, synovial sarcoma, and Wilms tumor. Out of this research has come not only an increased understanding of oncogenesis but also, for each of the tumors listed above, diagnostic and/or prognostic markers that can be used by the pathologist and oncologist to improve overall patient management.

Molecular analysis of Ewing's sarcoma: another fusion gene, EWS-E1AF, available for diagnosis

Ewing's sarcoma, one of the most malignant tumors of children and young adults, expresses specific chimeric genes, e.g. EWS-FLI-1, EWS-ERG, EWS-ETV1 and EWS-FEV. In this paper, we extensively characterized a new fusion gene, EWS-EIAF by means of whole cDNA sequencing, RNA blot analysis, DNA blot analysis and chromosomal analysis, and showed it to be available for the diagnosis of Ewing's sarcoma and to participate in the oncogenesis of Ewing's sarcoma. Furthermore, we conducted a genetic analysis of Ewing family tumors in conjunction with immunohistochemical analysis and ultrastructural analysis. Our results demonstrate some limitations of both genetic analysis and histopathological analysis, and establish the relationship between neurogenic phenotypes and chimera genes.

[New biological prognostic factors of soft tissue sarcoma. SFOP (Société française d'oncologie pédiatrique)]

Malignant tumors of soft tissue constitute a very heterogeneous group of tumors which is composed of more than 50 different entities derived from either the mesenchyme or the neuroectoderm. Diagnostic problems can be linked to the difficulty to firmly establish the diagnosis of malignancy and to the precise determination of the type of sarcoma. The prognostic is largely dependent on local and distant extension of the cancer. The study of the genotype of tumor cells has enabled the detection and characterization of genetic alterations. These alterations, frequently chromosome translocations, are specific markers for subgroups of tumors and can thus be of clinical relevance. These markers can be detected by cytogenetic, in situ hybridization or molecular biology techniques. The specificity of these alterations for tumor cells and the possibility to detect them with the highly sensitive polymerase chain reaction (PCR) technique have enabled development of tests aimed at the detection of tumor cells within potential metastatic sites.

Cloning of a novel human ELF-1-related ETS transcription factor, ELFR, its characterization and chromosomal assignment relative to ELF-1

The ETS gene family encodes a group of proteins that function as transcription factors under physiological conditions and, if aberrantly expressed, can lead to cellular transformation. ETS transcription factors are characterized by a unique conserved DNA binding domain. A subset of these proteins is rearranged with EWS in Ewing tumors (ET). We recently described a spectrum of ETS genes coexpressed with EWS-FLI1 in an ETcell line to define proteins that potentially compete in target site selection. We now report on the cloning and characterization of a novel ETS family member, ELFR, displaying 92% homology to ELF-1 in its DNA binding domain while diverging in the rest of the protein. ELFR expression was found in a very tissue restricted pattern with the highest abundancy in placenta. We also report the chromosomal assignment of ELFR and ELF-1 to Xq26 and 13q13, respectively, by means of fluorescence in-situ hybridization (FISH).

Primary cutaneous Ewing's sarcoma: immunophenotypic and molecular cytogenetic evaluation of five cases

Cutaneous small blue cell tumors are relatively uncommon and include primary lesions of either adnexal or neuroendocrine differentiation, as well as metastatic disease. Extraosseous Ewing's sarcoma/malignant primitive neuroectodermal tumor (MPNET) rarely may occur as a primary, superficially based neoplasm in children and young adults. We describe a series of five cases of Ewing's sarcoma/malignant primitive neuroectodermal tumor occurring as a primary cutaneous malignancy supported diagnostically both by immunohistochemical stains and fluorescence in situ hybridization (FISH). All five cases occurred as a solitary dermal nodule and were located in the lower extremities (3 cases), the axilla (1 case), and the flank (1 case). Three of the cases were clinically polypoid. Four of the five patients were female, and age at presentation ranged form 8 to 50 years of age (median, 18 years). All five tumors consisted of nodular proliferations of monomorphous, small blue cells with round, vesicular nuclei, and scant to moderate cytoplasm that were uniformly immunoreactive for the CD99 cell surface glycoprotein in a characteristic membranous pattern. Fluorescence in situ hybridization analysis of paraffin-embedded tissue revealed that three of four tumors were positive for a chromosomal translocation involving the EWS locus at 22q12, seen in more than 90% of cases of Ewing's sarcoma/malignant primitive neuroectodermal tumor. One case was not analyzable. All five patients were treated using local excision, and two patients additionally received postoperative chemotherapy and radiotherapy. Clinical follow-up is available in three cases (median duration, 33 months) and to date none has shown evidence of either local recurrence or metastasis. Because similar cases reported in the literature have likewise had favorable clinical courses after excision, primary cutaneous Ewing's sarcoma/malignant primitive neuroectodermal tumor may represent a clinically favorable subset of this otherwise highly aggressive neoplasm.

Expression of E1AF, an ets-family transcription factor, is correlated with the invasive phenotype of oral squamous cell carcinoma

E1AF is a newly identified ets-oncogene family transcription factor. Previous reports have noted that E1AF can upregulate promoter activities of several matrix metalloproteinase (MMP) genes and showed that invasive potentials of oral squamous cell carcinoma-derived cell lines are correlated with expression of E1AF and MMPs. The invasive phenotype is restrained by transfection with an antisense E1AF expression vector. Thus, E1AF is thought to be highly correlated with malignant potentials of cancer cells. However, little is known about E1AF expression and cancer cell malignancies in in vivo tumours. In the present study, 27 oral squamous cell carcinoma (SCC) specimens were examined using RT-PCR, Southern blot hybridisation and in situ hybridisation (ISH) and compared to the clinicopathological parameters. Among the 27 patients, E1AF was detected in 15 cases. E1AF mRNA was detected in 13 of 17 invasive SCCs, whereas the majority of SCCs not expressing E1AF showed an expansive growth pattern. Increased prevalence of E1AF-positive oral SCC was observed in cases with nodal metastasis. These results indicate that E1AF may be involved in cancer cell malignancies through its ability to promote invasive potential.

Production and characterization of mouse monoclonal antibodies to wild-type and oncogenic FLI-1 proteins

Mouse monoclonal antibodies were raised against the C-terminal domain of human FLI-1, a member of the ETS family of transcription factors which is involved in various murine and human malignancies. This FLI-1 specific domain is included in the fusion product EWS-FLI-1, an oncogenic variant of FLI-1 expressed in Ewing tumors. Antibodies were screened first by enzyme-linked immunosorbent assay onto recombinant FLI-1-coated plates. Positive clones were then tested for their ability to immunoprecipitate over-expressed EWS-FLI-1 protein. Three monoclonal antibodies were selected and further characterized. One of them, termed 7.3 MoAb, was shown to react with FLI-1 and EWS-FLI-1 in immunoblotting, immunoprecipitation, and immunofluorescence experiments. With all three methods, this antibody not only enabled the detection of overexpressed proteins but also more interestingly, that of endogenously expressed proteins. Furthermore, the 7.3 MoAb can specifically inhibit the interaction of FLI-1 with its DNA-binding site as shown by electrophoretic mobility shift assay. The 7.3 MoAb appears to be specific for FLI-1 because it does not react with ERG, the ETS family member most closely related to FLI-1. This antibody should be a useful tool in the diagnostic evaluation of Ewing tumors and should permit biochemical analyses to study the function of the wild-type FLI-1 protein and of the EWS-FLI-1 fusion protein.

Structure-function relationships of the PEA3 group of Ets-related transcription factors

The PEA3 group of transcription factors belongs to the Ets family and is composed of PEA3, ERM, and ER81, which are more than 95% identical within the DNA-binding domain--the ETS domain--and which demonstrate 50% aa identity overall. We present here a review of the current knowledge of these transcription factors, which possess functional domains responsible for DNA-binding, DNA-binding inhibition, and transactivation. Recent data suggest that these factors are targets for signaling cascades, such as the Ras-dependent ones, and thus may contribute first to the nuclear response to cell stimulation and second to Ras-induced cell transformation. The expression of the PEA3 group members in numerous developing murine organs, and, especially, in epithelial-mesenchymal interaction events, suggests a key role in murine organogenesis. Moreover, their expression in certain breast cancer cells suggests a possible involvement of these genes in the appearance, progression, and invasion of malignant cells.

Additional evidence of a variant translocation t(12;22) with EWS/CHOP fusion in myxoid liposarcoma: clinicopathological features

It is well established that the majority of myxoid/round cell liposarcomas (LPS) are characterized by a reciprocal translocation t(12;16)(q13;p11) which at the molecular level results infusion of the CHOP and FUS/TLS genes. It is assumed that functional characterization of these genes may provide insight into the molecular pathogenesis of this tumour type. This study describes two new cases of myxoid/round cell LPS having a t(12;22). By reverse transcription-polymerase chain reaction (RT-PCR) it has been shown that this leads to fusion between the CHOP and EWS genes, thus indicating involvement of the EWS gene, at least occasionally, in yet another sarcoma type. Combining these two cases with two others which were recently similarly characterized at the molecular level, their clinicopathological features have been compared with cases having the more usual t(12;16). It was not possible to identify any clinical or pathological differences between these molecular genetic subsets. The relevance or significance of these gene fusion products in myxoid/round cell LPS remains to be determined.

Characterization and chromosomal mapping of the human TFG gene involved in thyroid carcinoma

Homology searches in the Expressed Sequence Tag Database were performed using SPYGQ-rich regions as query sequences to find genes encoding protein regions similar to the N-terminal parts of the sarcoma-associated EWS and FUS proteins. Clone 22911 (T74973), encoding a SPYGQ-rich region in its 5' end, and several other clones that overlapped 22911 were selected. The combined data made it possible to assemble a full-length cDNA sequence. This cDNA sequence is 1677 bp, containing an initiation codon ATG, an open reading frame of 400 amino acids, a poly(A) signal, and a poly(A) tail. We found 100% identity between the 5' part of the consensus sequence and the 598-bp-long sequence named TFG. The TFG sequence is fused to the 3' end of NTRK1, generating the TRK-T3 fusion transcript found in papillary thyroid carcinoma. The cDNA therefore represents the full-length transcript of the TFG gene. TFG was localized to 3q11-q12 by fluorescence in situ hybridization. The 3' and the 5' ends of the TFG cDNA probe hybridized to a 2.2-kb band on Northern blot filters in all tissues examined.

Ten years of the cytogenetics of soft tissue tumors

Recent cytogenetic and molecular genetic investigations in solid tumors in general, and in soft tissue tumors in particular, have provided us with a wealth of information. We have gained new insights in how tumors may arise, and some soft tissue tumors besides their identification by pathology now also have a genetic identity. This genetic identity is defined by: specific chromosome changes and by molecular changes related to the chromosome anomalies. However, much work remains to be done. In soft tissues as in other solid tumors many tumor types await the first or more extensive chromosome investigation, and in those in which nonrandom, especially simple chromosome changes emerge, molecular studies are to be undertaken starting from the breakpoints. Those tumors that seem to deviate chromosomally or molecularly from the expected, because of already established genetic changes, must be more thoroughly investigated by both pathologists and geneticists. The same accounts for the molecular investigation of chromosomally normal tumors known to show subtypes with specific chromosomal changes: e.g. lipoma, leiomyoma.

Two transcription factors, E1AF and N-myc, correlate with the invasiveness of neuroblastoma cell lines

The ets transcription factor E1AF can activate several matrix-degrading metalloproteinase (MMP) genes and is implicated in enhancement of tumor cell invasion. Here we compared the invasive activity of five human neuroblastoma cell lines (TGW, GOTO, SK-N-BE, SK-N-SH and SK-N-AS), which exhibit distinct levels of N-myc amplification, together with the expression of E1AF. Extracellular matrix-degrading proteases and their inhibitor proteins, which play an important role in local invasion, were also analyzed. The activity to invade through reconstituted basement membrane was high in cells (TGW, GOTO, and SK-N-BE) with N-myc amplification, and these cells produced relatively large amounts of E1AF mRNA, correlating with the invasive activities. Of several matrix metalloproteinases (MMPs) and a tissue inhibitor of MMPs (TIMP), only membrane-bound type 1 MMP (MT1-MMP) was specifically detected in N-myc-amplified cells, suggesting a role of MT1-MMP in neuroblastoma cell invasion. MMP-2 (72 kD type IV collagenase), TIMP-1 and TIMP-2 were expressed in all five cell lines. Urokinase-type plasminogen activator was undetectable. These findings indicate that the transcription factors E1AF and N-myc are related to malignant phenotypes of neuroblastoma.