Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromosome translocations found in neoplasms often result in the creation of hybrid genes encoding chimeric proteins. This case study describes a patient with desmoplastic small round cell tumor (DSRCT) of the abdomen, an aggressive neoplasm characterized by translocation of chromosomes 11 and 22. Southern hybridization showed that the Ewing sarcoma gene (EWS) gene was rearranged in the DSRCT. Reverse transcriptase-polymerase chain reaction analysis of tumor cell RNA revealed that exons 1 to 7 of the EWS gene were joined to exons 8 to 10 of the Wilms' Tumor-1 (WT-1) gene resulting in the production of a chimeric message. The WT-1 and EWS genes encode DNA and RNA binding proteins involved in Wilms' tumor and Ewing sarcoma pathogenesis, respectively. The fusion of these two genes in DSRCT results in the production of a putatively oncogenic protein composed of the zinc finger DNA binding domains of WT-1 linked to potential transcriptional regulatory domains of EWS. DNA sequencing revealed the genomic breakpoints of translocation on chromosomes 11 and 22. The genomic breakpoint on chromosome 22 occurred in EWS intron 7 just 2 nucleotides 3' of exon 7. Polymerase chain reaction-based assays were developed that could detect the fused genes in the DSRCT tumor using either RNA or genomic DNA. The potential diagnostic use of these assays is discussed.
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PMID:EWS and WT-1 gene fusion in desmoplastic small round cell tumor of the abdomen. 852 11

A t(11;22)(p13;p12) chromosomal translocation, juxtaposing the Wilms' tumor (WT1) and Ewing's sarcoma (EWS) genes, is the cytogenetic hallmark of desmoplastic small round cell tumor (DSRCT), a primitive multiphenotypic sarcoma arising in serosal tissues. Chimeric transcripts generated by this rearrangement encode an aberrant transcription factor that fuses the 5' region of EWS with a 3' WT1 segment. We describe the insertion of a LINE-I DNA mobile genetic element at the genomic breakpoint of a DSRCT chromosomal translocation. A 480 bp heterologous DNA segment with homology to the LINE-I DNA consensus sequence was located between EWS intron 8 and WT1 exon 8 in the productively rearranged allele. Sequence homology corresponded to the LINE-I ORF-2, which encodes a protein with reverse-transcriptase activity. The heterologous inserted fragment was not evident in the germline of normal tissue from the patient, suggesting that transposition occurred in somatic cells, possibly during the process of chromosomal rearrangement. This case represents the first example of LINE-I DNA transposition at the fusion site of a tumor-associated chromosomal rearrangement.
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PMID:LINE-I element insertion at the t(11;22) translocation breakpoint of a desmoplastic small round cell tumor. 907 77

We report here a 15-year-old boy with an intraabdominal desmoplastic small round cell tumor (DSRCT). Cytogenetic analysis of the tumor cells showed the chromosomal translocation (11;22). Reverse-transcriptase polymerase chain reaction and sequencing analysis revealed a chimeric transcriptional message of the EWS gene exon 10 fused to the WT1 gene exon 8. The typical chimeric transcript seen in DSRCT is an in-frame fusion of EWS exon 7 to WT1 exon 8. The tumor in this case had a novel and longer chimeric transcript, which should be a potent transcription factor. Genetic analysis is a very powerful and specific aid in the differential diagnosis of small round cell tumors.
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PMID:Novel breakpoints of the EWS gene and the WT1 gene in a desmoplastic small round cell tumor. 979 82

Desmoplastic small round cell tumor (DSRCT) is a unique, highly aggressive neoplasm that chiefly affects male adolescents and young adults. This tumor is characterized by nests of small undifferentiated cells that show immunohistochemical evidence of epithelial, mesenchymal, and neural differentiation. We report two cases of DSRCT that lacked immunohistochemical evidence of epithelial differentiation, but were found to have the fusion transcripts characteristic of this tumor. Both patients (a 41-year-old male and a 31-year-old female) presented with large intra-abdominal masses. After diagnostic biopsy, both were treated with multi-agent chemotherapy. One patient expired 18 days after diagnosis, and the other is currently alive 28 months later. Histologically, both tumors had the characteristic features of DSRCT and were composed of small round cells with hyperchromatic nuclei and scanty cytoplasm. In one of the cases, perinuclear intracytoplasmic hyaline inclusions were seen. Immunohistochemically, neither case expressed any of the epithelial markers tested, including AE1/AE3, CAM 5.2 and EMA. Both tumors were diffusely immunoreactive for desmin with a prominent globoid "dot-like" pattern of staining in one case. Both tumors stained for vimentin, neuron specific enolase, and synaptophysin, but were negative for CD99, muscle-specific actin, and myogenin. Reverse transcriptase-polymerase chain reaction revealed EWS-WT1 fusion transcripts characteristic of this neoplasm. In conclusion, we describe two cases of DSRCT that lacked immunohistochemical evidence of epithelial differentiation but had histologic and other immunohistochemical features which suggested this diagnosis. The ability to confirm the diagnosis of this rare tumor using molecular genetic techniques is particularly useful in those cases with unusual histologic or immunophenotypic features.
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PMID:Cytokeratin-negative desmoplastic small round cell tumor: a report of two cases emphasizing the utility of reverse transcriptase-polymerase chain reaction. 1049 92

examination. The patient died 10 months after surgery. Histologically, the tumor was composed of predominantly large epithelioid cells with foci of anaplasia mimicking metastatic carcinoma. Immunohistochemically, the tumor cells stained with anti-cytokeratin, EMA, desmin, and NSE antisera. Electron microscopy showed secretory lumina, desmosomes, cell processes with microtubules and electron-dense granules, and focal whorls of intermediate filaments. Reverse transcriptase-polymerase chain reaction performed on paraffin block-retrieved tissue demonstrated the EWS/WT-1 fusion transcript characteristic of the t(11;22)(p13;q12). This case illustrates a less common histological pattern of DSRCT, i.e., diffuse large cells, thus supporting the view that this tumor presents a wider morphological spectrum than that previously recognized.
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PMID:Desmoplastic small round-cell tumor: a case report on the large cell variant with immunohistochemical, ultrastructural, and molecular genetic analysis. 1107 72

Desmoplastic small round cell tumor (DSRCT) is a rare undifferentiated neoplasm. The prognosis is poor, even if therapy is instituted promptly, and thus it is important to differentiate it from other histologically and cytologically similar-looking malignancies of the young adult. We present a case of DSRCT in a 17-yr-old male with disseminated peritoneal disease and peritoneal effusion. The cytology sample showed a malignant small round cell tumor, the classical cytological features of DSRCT, and immunohistochemistry performed in the prepared cell block exhibited an antibody expression profile in keeping with DSRCT. Further material from the effusion was prepared for RNA extraction, following which a reverse-transcriptase polymerase chain reaction (RT-PCR) and sequencing of the t(11;22)(p13;q11 or q12) were carried out. The result showed the presence of the reciprocal translocation and thus confirmed the diagnosis of DSRCT. This case shows how molecular techniques (including sequencing) can be applied to cytology in clarifying and confirming certain difficult diagnosis of undifferentiated neoplasms, DSRCT in this particular case.
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PMID:Sequence confirmation of the EWS-WT1 fusion gene transcript in the peritoneal effusion of a patient with desmoplastic small round cell tumor. 1464 92

We present a 51 year old female patient with a pelvic desmoplastic small round cell tumor with an unusual immunohistochemical profile, including absence of significant cytokeratin expression, complete negativity for desmin and widespread loss of nuclear INI-1 expression (>90% of tumor cells). The neoplastic cells were positive for epithelial membrane antigen (EMA), vimentin, and WT-1 (antibody against the C-terminus). The tumor showed classic histopathological features with no rhabdoid cells. Fluorescent in situ hybridization revealed EWSR1 gene rearrangement and absent SYT gene rearrangement. Reverse transcriptase polymerase chain reaction showed presence of EWSR1-WT1 transcript.
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PMID:Beware of immunohistochemistry--report of a cytokeratin-, desmin- and INI-1-negative pelvic desmoplastic small round cell tumor in a 51 year old woman. 2575 5