Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Childhood cutaneous and subcutaneous malignancies are rare and include metastatic tumors of diverse histogenesis as well as primary lesions, such as sweat gland carcinomas. Some cutaneous malignancies exhibit a small round cell tumor morphology with few definitive differentiating features; they can thus pose a significant diagnostic problem. We describe two primary malignancies of the skin and superficial subcutis, which were originally diagnosed as sweat gland carcinomas on the basis of their morphological features. A cytogenetic analysis performed on one of these lesions showed the t(11;22)(q24;q12) rearrangement, believed to be unique to the Ewing's sarcoma/peripheral primitive neuroectodermal tumor (ES/pPNET) group of neoplasms. In view of this unexpected result, reverse transcriptase-polymerase chain reaction analysis was performed on both lesions and showed that they expressed EWS/FLI-1 fusion gene mRNA transcripts, the molecular equivalent of t(11;22)(q24;q12). The two tumors also had an immunohistochemical profile suggesting ES/pPNET, including strong expression of the MIC2 antigen. Both patients were treated with wide local excision, and one was given a course of chemotherapy. Neither patient showed evidence of tumor elsewhere after follow-up periods of 2 years and 16 years. These findings suggest that these tumors are indeed a form of primary ES/pPNET arising in the skin or superficial subcutis, which may be of low-grade malignancy and curable by local surgery.
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PMID:Primary cutaneous Ewing's sarcoma/peripheral primitive neuroectodermal tumors in childhood. A molecular, cytogenetic, and immunohistochemical study. 749 36

Desmoplastic small round cell tumor is a recently described entity associated with fusion of the EWS and WT1 genes and with expression of a chimeric transcript. To investigate the structure and potential diagnostic utility of the detection of EWS-WT1 chimeric RNA in desmoplastic small round cell tumor, 12 examples of this entity and 49 other tumors that enter in its differential diagnosis were studied by reverse transcriptase polymerase chain reaction for the presence of EWS-WT1, EWS-FLI-1, PAX3-FKHR, and PAX7-FKHR chimeric transcripts. EWS-WT1 was detected in 11 of 12 desmoplastic small round cell tumors but not in any other tumor type studied, including 17 Wilms' tumors, 10 Ewing's sarcomas/primitive neuroectodermal tumors, 13 alveolar rhabdomyosarcomas, and 9 embryonal rhabdomyosarcomas. One desmoplastic small round cell tumor was found to have a variant EWS-WT1 chimeric product that included exon 8 of EWS EWS-FLI-1 chimeric RNA was present in all Ewing's sarcoma/primitive neuroectodermal tumor and not identified in any other tumor types, including desmoplastic small round cell tumor. PAX3/PAX7-FKHR chimeras were present in 9 of 13 alveolar rhabdomyosarcomas but not in any other tumors. Detection of chimeric transcripts by reverse transcriptase polymerase chain reaction is a very specific aid in differential diagnosis of developmental tumors and further establishes desmoplastic small round cell tumor as a distinct entity.
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PMID:Detection of chimeric transcripts in desmoplastic small round cell tumor and related developmental tumors by reverse transcriptase polymerase chain reaction. A specific diagnostic assay. 749 83

The peripheral primitive neuroectodermal tumors (pPNETs) of childhood, including Ewing's sarcoma, peripheral neuroepithelioma, and Askin's tumor, often present significant diagnostic challenges for the anatomic pathologist. One consistent feature of these tumors is the presence of the t(11;22)(q24;q12) in tumor cells, and this translocation has been useful as a marker for this group of tumors. The recent cloning of the t(11;22) breakpoint has revealed the fusion of the human FLI-1 gene on chromosome 11q24 with a gene of unknown function called EWS on 22q12, and fusion transcripts have been detected. These findings have raised the possibility of using molecular genetic analysis as a tool to diagnose pPNETs. To this end, we have tested pPNETs for the presence of EWS/FLI-1 fusion transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) using EWS and FLI-1 specific primers. Eight (80%) of 10 pPNET cell lines were positive for amplified products using this technique. These results were confirmed by Southern analysis, which revealed rearrangements of EWS using genomic EWS probes in all eight positive cell lines. We then tested 20 primary pPNET tumors, and identified fusion transcripts by RT-PCR in 18 (90%) of these cases. Cloning and sequencing of PCR products confirmed the presence of EWS and FLI-1 sequences in these products. Furthermore, fusion transcripts were not detected by this technique in a series of non-pPNET pediatric solid tumors. Detection of EWS/FLI-1 fusion transcripts by RT-PCR therefore provides a novel adjunctive tool in the diagnosis of pPNETs.
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PMID:Reverse transcriptase PCR amplification of EWS/FLI-1 fusion transcripts as a diagnostic test for peripheral primitive neuroectodermal tumors of childhood. 750 81

Recent cloning of the t(11;22) region has led to the detection of a number of sequences involved in the breakpoints by substituting a sequence which encodes a putative RNA binding domain for that of the DNA binding domain of the human homologue of murine FLI-1. Several tumours display consistent translocation at t(11;22) (q24;q12), a finding that suggests these fusion transcripts could be expressed and detected by reverse transcriptase polymerase chain reaction amplification. To date, only a small number of Ewing's sarcomas (Es) and peripheral neuroectodermal tumours (pPNET) of bone have been tested with this novel molecular biology approach. In this study, we confirmed the presence of the three putative chimaeric transcripts on 7 cases of Es and pPNET sarcomas of bone and soft tissue, providing 100% positivity for the tested tumours. For comparative purposes, a number of other neuroectodermal tumours were analysed with negative results: esthesioneuroblastoma, retinoblastoma, Schwannoma. A primitive soft tissue sarcoma (ectomesenchymoma) with a 22 chromosome rearrangement did not express any transcript, nor did a number of non-neuroectodermal small round cell sarcomas of soft tissue (rhabdomyosarcomas) and bone (microcellular osteosarcoma), conventional bone sarcomas, leiomyosarcomas, malignant fibrous histiocytomas and synovial sarcomas. These results reinforce the value of molecular biology techniques for the correct assessment of histology difficult evaluable neoplasms, such as the group of small round cell tumours within the Es family.
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PMID:EWS/FLI-1 rearrangement in small round cell sarcomas of bone and soft tissue detected by reverse transcriptase polymerase chain reaction amplification. 752 96

Recently, Ewing's tumours have been shown to carry specific hybrid transcripts resulting from the fusion of the EWS gene with FLI-1 or ERG genes. Based on the sensitivity and specificity of the detection of these alterations by the reverse transcriptase-polymerase chain reaction technique, we have developed an assay to search for small numbers of Ewing cells in various sites from patients with Ewing's tumour. This method enables the detection of fewer than one tumour cell per million blood mononuclear cells. A total of 28 primary sites and 51 peripheral samples from 36 patients were investigated. Tumour cells could be detected in 4/18 blood samples, 4/15 bone marrow aspirates and 2/18 peripheral stem cell harvests. EWS/FLI-1 and EWS/ERG transcripts being observed in eight and two cases respectively. The type of fusion transcript detected in peripheral site(s) was identical to that observed in the primary site. At diagnosis 5/16 patients (31%) demonstrated either circulating tumour cells or/and occult bone marrow metastasis. After induction therapy, tumour cells were detected in 3/21 patients. This highly sensitive method should be a relevant tool to allow a more accurate clinical assessment of the dissemination of Ewing's tumours.
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PMID:Sensitive detection of occult Ewing's cells by the reverse transcriptase-polymerase chain reaction. 759 72

Cytogenetic analysis of peripheral primitive neuroectodermal tumors (PNETs) has demonstrated a consistent primary chromosomal change characterized by a reciprocal translocation t(11;22)(q24:q12). In the central nervous system PNETs, most frequent of which are the cerebellar medulloblastomas, the most prevalent chromosomal abnormalities include deletions and unbalanced translocations. The recent cloning of the t(11;22) breakpoint has revealed the fusion of the human FLI-1 gene on chromosome 11q24 with a gene EWS on chromosome 22q12 and permitted detection of fusion transcripts. Molecular genetic analysis for the presence of EWS/FLI-1 fusion transcripts by the reverse transcriptase-polymerase chain reaction has recently been applied to peripheral PNETs. In the present study, we analyzed eight central PNETs by reverse transcriptase-polymerase chain reaction for EWS/FLI-1 fusion transcripts. The tumors included six PNETs of the cerebellum, one supratentorial PNET of the frontal lobe and one PNET of the pineal region. Polymerase chain reaction analysis in all eight cases failed to reveal a t(11;22) translocation indicating that this is not a cytogenetic abnormality of the central PNETs. Reverse transcriptase-polymerase chain reaction analysis of EWS/FLI-1 fusion transcripts provides a novel adjunctive tool in the differentiation of central versus peripheral PNET.
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PMID:Primitive neuroectodermal tumors of the cerebrum and cerebellum: absence of t(11;22) translocation by RT-PCR analysis. 767 66

Cytogenetic analysis has defined specific translocations associated with two of the most common small round cell tumors of childhood, t(11;22) in Ewing's sarcoma and t(2;13) in alveolar rhabdomyosarcoma. We and others have previously demonstrated the diagnostic utility of a reverse transcriptase polymerase chain reaction (RT-PCR) assay for the detection of the t(11;22) encoded EWS/FLI-1 chimeric message in Ewing's sarcoma. More recently, we have cloned the t(2;13)(q35;q14) translocation and have shown that it results in the fusion of the PAX3 gene on chromosome 2 to FKHR, a novel member of the fork-head family of transcription factors on chromosome 13. To define the morphological spectrum of childhood sarcomas that express the t(2;13) encoded PAX3/FKHR chimeric message, we have performed RT-PCR analysis on samples from 44 primary pediatric sarcomas and 8 sarcoma cell lines. PAX3/FKHR chimeric messages were detected in 24 of 27 alveolar, 2 of 12 embryonal, and 0 of 1 pleomorphic rhabdomyosarcoma and in 1 of 2 ectomesenchymomas. In contrast, none of 8 Ewing's sarcomas or 2 undifferentiated sarcomas expressed this message. Chimeric transcripts were detected in all cases with cytogenetic evidence of the (2;13) translocation, and in each case the chimeric PAX3/FKHR message had the identical junction sequence, suggesting that genomic chromosome breaks were clustered in a single intron in both genes. By combining the PAX3/FKHR RT-PCR assay with primers for detection of the Ewing's sarcoma t(11;22) encoded EWS/FLI-1 chimeric transcript, we have developed a multiplex RT-PCR reaction that allows the rapid and accurate identification of either translocation in a biopsy sample.
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PMID:Multiplex RT-PCR assay for the differential diagnosis of alveolar rhabdomyosarcoma and Ewing's sarcoma. 788 45

The identification of Ewing's sarcoma (ES) and peripheral neuroectodermal tumor (PNET) among other small round cell tumors (SRCTs) is a critical issue in musculoskeletal pathology because of the lack of clearly distinctive morphological features. In this study, the authors have compared advantages and limits of two procedures that were recently suggested as additional tools for the identification of ES/PNET, the analysis of p30/32MIC2 antigen by immunohistochemistry, and the evaluation of the fusion products of two specific chromosomal aberrations, the t(11;22)(q24;q12) and the t(21;22)(q22;q12), by reverse transcriptase-polymerase chain reaction (RT-PCR). The authors have analyzed the expression of p30/32MIC2 in 28 cell lines and in 90 tumor samples. p30/32MIC2 was highly expressed in ES/PNET but was also present in all the other cell types. The broad spectrum of positivity for p30/32MIC2 in SRCTs of bone was substantially confirmed by the analysis of tissue samples. In the same material, the authors have evaluated the presence of t(11;22) or t(21;22) transcripts (EWS/FLI-1 and EWS/ERG, respectively) by RT-PCR. These transcripts were found in all the cell lines and tissue samples of ES/PNET, but not in other tumors. The authors' results question the use of p30/32MIC2 immunostaining alone for the identification of ES/PNET and suggest the adoption of RT-PCR as an advantageous alternative. Molecular diagnosis of ES/PNET by RT-PCR is highly specific and can be applied to small amounts of tissue. Moreover, RNA extracted from paraffin-embedded specimens was shown to be suitable for RT-PCR analysis, thus enabling analysis of archival material.
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PMID:Immunostaining of the p30/32MIC2 antigen and molecular detection of EWS rearrangements for the diagnosis of Ewing's sarcoma and peripheral neuroectodermal tumor. 861 85

Ewing's sarcoma (ES) and other primitive peripheral neuroectodermal tumors (pPNETs) can present a significant diagnostic problem, as they may morphologically resemble other small round cell tumors (SRCTs) of childhood. However, ES/pPNET is known to carry a characteristic t(11;22)(q24;q12), the detection of which may aid diagnosis. The recent identification of the EWS and FLI-1 genes flanking the translocation break point has enabled reverse transcriptase-polymerase chain reaction (RT-PCR) to be used to detect the putative chimeric transcription factor mRNA produced by the fusion gene. We have assessed the RT-PCR method of detection by examining 40 cases of ES for the presence of EWS/FLI-1 transcripts. Twenty-six (76%) of the 34 cases with intact mRNA yielded fusion transcripts. Four different transcript sizes were detected and two tumors contained two transcripts of different size. No transcripts were detected in a control group of non-ES/pPNET SRCTs. Eight cases with intact mRNA were transcript negative. The MIC2 cell surface antigen, which is reported to be present in over 95% of ES/pPNETs, was present in 32 of 33 tumors (97%), including all 24 EWS/FLI-1 transcript-positive cases examined. Hence MIC2 is a useful screen for ES, with RT-PCR detection of t(11;22) being the optimal method for confirming the diagnosis.
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PMID:EWS/FLI-1 fusion transcript detection and MIC2 immunohistochemical staining in the diagnosis of Ewing's sarcoma. 902 40

Peripheral primitive neuroectodermal tumour (pPNET or peripheral neuroepithelioma) is one of the malignant small round cell tumours of peripheral nerves, soft tissues and bones, but rarely originates in the spinal canal. We report an example of pPNET arising in the cauda equina of a 14-year-old Japanese boy. At surgery, a well-demarcated tumour measuring 2 x 4 cm in diameter and involving one of the nerve roots of the cauda equina was located within the intradural space with no evidence of extradural extension. Microscopically the tumour was made up of sheets of closely packed small round cells, associated with ganglioneuroma-like islands. Immunohistochemically, the small round tumour cells were intensely positive for neuron-specific enolase (NSE), an MIC2 gene product (O13) and beta 2-microglobulin, whereas the foci with ganglion cell-like cells reacted positively to NSE, synaptophysin and beta 2-microglobulin but were negative for O13. A chimeric transcript of the EWS/FLI-1 fusion gene detected by a nested reverse transcriptase-polymerase chain reaction using formalin-fixed paraffin-embedded tissue justified the diagnosis of pPNET. Only 6 cases of PNET in the cauda equina have been described in the literature, and this is the first case of a pPNET with ganglio-neuroma-like areas. This finding suggests that the primitive tumour cells of pPNET may respond to unknown inductive effects and express a ganglion cell-like morphology.
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PMID:Peripheral primitive neuroectodermal tumour with ganglioneuroma-like areas arising in the cauda equina. 946 79


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